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<h1>ICSV14: 14th International Congress on Sound and Vibration (ICSV14)<br>
Venue, Location, Date</h1>
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<p style="font-weight: bold; text-align: center;"><font size="+2">Table of Contents</font></p>
<ul id="Toc">
<ul>
<li>R-Acoustic ecology</li>
<ul>
<li><a href="#p542">Acoustic Detection of Tension Wood in Eucalypts</a></li>
<li><a href="#p699">The Safeguarding of Marine Mammals Development of Detection Methods in a Blast Environment</a></li>
</ul>
<li>R-Acoustics and vibration theory</li>
<ul>
<li><a href="#p278">An Asymptotic Approach for the Coupled Dispersion Characteristics of a Fluid-Filled Cylindrical Shell</a></li>
<li><a href="#p295">Stochastic Finite Element Analysis of the Free Vibration of Functionally Graded Material Plates</a></li>
<li><a href="#p751">Acoustically Controlled Rotations of a Disk in Free Field</a></li>
<li><a href="#p494">Dependence of Oscillational Instabilities on the Amplitude of the Acoustic Wave in Single-Axis Levitators</a></li>
<li><a href="#p90">Zero-Pole Analysis of a Tensioned String with Periodic Stiffeners</a></li>
<li><a href="#p399">Modal Probabilistic Analysis: Theory and Application</a></li>
<li><a href="#p82">The Use of the Propagation Equation for the Case of Plane Longitudinal Waves Through Bars with Variable Section, to Study the Impedance Transformers Utilized for Ultrasonic Welding</a></li>
<li><a href="#p229">Vibration Analysis of a Cracked Beam Subjected to a Traveling Vehicle</a></li>
<li><a href="#p496">Estimation of the Active and Reactive Sound Power Using Hyper-Matrices of Impedance</a></li>
<li><a href="#p436">Vibration Control Method of Speaker Enclosure and its Effect on Replay Sound Quality and Summing Localization</a></li>
<li><a href="#p365">Parametric Vibrations of the Rotor</a></li>
<li><a href="#p44">Gyroscopic Effects in Vibrating Fluid-Filled Spheres Subjected to Inertial Rotation</a></li>
<li><a href="#p48">Investigation of Gyroscopic Effects in Vibrating Fluid-Filled Cylinders Subjected to Axial Rotation</a></li>
<li><a href="#p49">On Gyroscopic Effects in Vibrating and Axially Rotating Solid and Annular Discs</a></li>
<li><a href="#p626">Statistical Energy Analysis Using Transmission Coefficients Derived for Finite Coupled Plates</a></li>
<li><a href="#p688">Study on the Characteristics of Vibration and Acoustic Radiation of Damaged Stiffened Panels</a></li>
<li><a href="#p500">Sound Source Localization with Bio-Mimicking Parasitoid Fly</a></li>
<li><a href="#p706">Wave Propagation, Reflection and Transmission in Curved Beams</a></li>
<li><a href="#p763">Free Vibration Analysis of Sandwich Hemispherical Shells with Constrained Electro-Rheological Fluid Damping</a></li>
<li><a href="#p822">Two Observations on the Wave Approach to SEA</a></li>
<li><a href="#p734">Analysis of 1/2-Order Subharmonic Resonance in a Horizontally Supported Jeffcott Rotor</a></li>
<li><a href="#p315">The Result Analysis of the Sound Intensity Level Generated by a High Power Transformer</a></li>
<li><a href="#p657">Vibration Based Modelling of Three Point Bend Specimen for Evaluation of Dynamic Stress Intensity Factor</a></li>
<li><a href="#p124">Some of the New Approaches to the Theory of Designing Acoustic Thickeners</a></li>
<li><a href="#p748">Dynamic Response of a Structure with Uncertainty in its Parameters and Applied Forces Using the Interval Factor Method</a></li>
<li><a href="#p71">Dynamic Analysis of Vehicles with Uncertain Parameters</a></li>
<li><a href="#p228">Dynamic Structure Modification Using Dents</a></li>
<li><a href="#p448">Some New General Results on the Fluid-Structure Interaction Problem</a></li>
</ul>
<li>R-Active noise and vibration control</li>
<ul>
<li><a href="#p758">Feedback Control of Piezo-Laminate Composite Plate</a></li>
<li><a href="#p613">Systematization of the Principles of Classification of Active Noise and Vibration Control Methods</a></li>
<li><a href="#p189">Active Control of Free Beam Vibrations Utilizing Actuator Optimization</a></li>
<li><a href="#p34">An Actuator Fault Detection Concept for Active Vibration Control of a Heavy Metro Vehicle</a></li>
<li><a href="#p812">Optimisation of active and semi-active noise and vibration control systems</a></li>
<li><a href="#p104">Robust Stability in Feedback Active Noise Control</a></li>
<li><a href="#p1">Active Noise Control with a Virtual Acoustic Sensor in a Pure-Tone Diffuse Sound Field</a></li>
<li><a href="#p161">Moment Control of the Sound Radiated from an Axially Excited Cylindrical Shell</a></li>
<li><a href="#p218">Vibroacoustic Control of Honeycomb Sandwich Panels Using MFC Actuators</a></li>
<li><a href="#p216">The Effect of Boundary Conditions on Active Control of Sound Radiation from a Rectangular Plate</a></li>
<li><a href="#p224">A Geometric Approach to the Optimal Design of Remotely Located Broadband Vibration Control Systems</a></li>
<li><a href="#p377">Active Vibration Clamping Absorber Design</a></li>
<li><a href="#p617">Control of Vehicle Suspension Using Nonlinear Energy Sink Controller</a></li>
<li><a href="#p197">Design of Command Shaper Using gain-Delay Units and Particle Swarm Optimisation for Vibration Control of a Flexible System</a></li>
<li><a href="#p283">Active Control of Interior Noise in a Rectangular Cavity with Two Flexible Panels</a></li>
<li><a href="#p232">Optimal Control of a Pretwisted Tapered Rotating Beam with Tip Rotor</a></li>
<li><a href="#p373">Adaptive Control of an Mr Mount for Vibration Attenuation</a></li>
<li><a href="#p524">Multi-Channel Adaptive Vibration Control of Smart Plate Using Hybrid Algorithm</a></li>
<li><a href="#p143">Robust Feedback Disturbance Rejection for Sound-Structure Interaction Systems Using Optimal Sensor - Actuator Location</a></li>
<li><a href="#p316">Evaluation Methodology of the Technical Condition of a Power Transformer Based on the Measurement Results of Mechanical Vibrations of its Tub</a></li>
<li><a href="#p314">Wavelet Analysis of the Power Transformer Tub Vibrations</a></li>
<li><a href="#p139">Optimization in Active Non-Stationary Random Vibration Control for Smart Truss Structures with Uncertainty</a></li>
<li><a href="#p589">Nonlinear Control of a One Axis Magnetic Spring</a></li>
<li><a href="#p140">Multidelay Adaptive Filters for Active Noise Control</a></li>
</ul>
<li>R-Aeroacoustics and aviation noise</li>
<ul>
<li><a href="#p449">Sound Radiation from a Buried Nozzle with Jet and Bypass Flow</a></li>
<li><a href="#p461">Turbomachinery Noise Radiation Through the Engine Exhaust (TURNEX)</a></li>
<li><a href="#p131">Internal Accoustic Excitation to Enhance the Airfoil Performance at High Reynolds Number</a></li>
<li><a href="#p438">Beamforming in Highly Reverberant Wind Tunnels Possibilities and Limitations</a></li>
<li><a href="#p288">Three-Dimensional Predictions of the Rod Wake-Airfoil Interaction Noise by Hybrid Methods</a></li>
<li><a href="#p47">Aeroacoustic Computations of a Counter-Rotating Fan</a></li>
<li><a href="#p105">Development and Validation of a Small-Scale Anechoic Wind Tunnel</a></li>
<li><a href="#p236">A Review of Selected Experimental Investigations of Curle’s Theory</a></li>
<li><a href="#p645">Two- and Three-Dimensional Coupling in the Noise Prediction of the Edge Tone</a></li>
<li><a href="#p431">Aft Fan Noise Reduction with a Lined Afterbody</a></li>
<li><a href="#p404">Comparison of Numerical Approaches for the Simulation of Sound Radiation from a Scarfed Inlet</a></li>
<li><a href="#p527">Aeroacoustic Investigation of a Tip Clearance Flow</a></li>
<li><a href="#p165">The Role of the Inflow Momentum Thickness in Subsonic Cylindrical Cavity Noise Generation</a></li>
<li><a href="#p629">Laminar Boundary Layer Instability Noise Produced by an Aerofoil</a></li>
<li><a href="#p362">Numerical Investigation of Aerodynamic Sound Radiated from a Bluff Body Using Lighthill Tensor</a></li>
<li><a href="#p137">A Source Term Formulation for the Non Linear Euler Equations in a Conservative and Perturbation Form</a></li>
<li><a href="#p6">3D Numerical Simulations of Acoustic Installation Effects on Aft Fan Noise for Turbofan Engine</a></li>
<li><a href="#p430">Frequency-Domain Prediction of Sound Propagation Through Axisymmetric Flow Ducts</a></li>
<li><a href="#p122">Large Eddy Simulation of Jet Noise</a></li>
<li><a href="#p186">Experimental Study of the Aircraft Engine Duct Combined Liners</a></li>
<li><a href="#p519">Time-Domain Acoustic Simulation of 3D Lined Ducts with Flow Using an Unstructured Discontinuous Galerkin Method</a></li>
</ul>
<li>R-Audiology</li>
<ul>
<li><a href="#p390">Aural Characteristic of the Bone Conduction Speaker on the Cheek Bone</a></li>
<li><a href="#p359">Binaural Directivity Pattern Measurements and Simulation of the KEMAR Head Model</a></li>
<li><a href="#p360">Digital Hearing Aid DSP Chip Parameter Fitting Optimization</a></li>
</ul>
<li>R-Bioacoustics</li>
<ul>
<li><a href="#p607">Assessment of the Smoothness of Surfaces with an Acoustical Probe</a></li>
<li><a href="#p304">Promotion of Extraction of Green Tea Catechins in Water Extraction at Low Temperature Using Ultrasound</a></li>
<li><a href="#p39">Use of Scattering of Ultrasound Pulses and Shock Waves by Kidney Stones for Imaging in Lithotripsy</a></li>
<li><a href="#p623">How Termites Use Vibration to Assess Potential Food Structures</a></li>
</ul>
<li>R-Community noise</li>
<ul>
<li><a href="#p425">Monitoring and Assessment of Aircraft Noise in an Airport’s Neighborhood</a></li>
<li><a href="#p712">Correlation of Rural Highway Road Traffic Noise with Vehicle Speed and Commercial Vehicle Percentages for the Day and Night Time Periods</a></li>
<li><a href="#p605">Protection against Noise on A6 Highway Rijeka-Zagreb, Karlovac-Novigrad Section</a></li>
</ul>
<li>R-Computational acoustics</li>
<ul>
<li><a href="#p475">Investigation of Quantum and Classical Models for Molecular Relaxation Using the Direct Simulation Monte Carlo Method</a></li>
<li><a href="#p696">Split Region Acoustical Wave Propagator and its Applications</a></li>
<li><a href="#p280">An Analysis of the Changes to the Mechanical and Acoustical Properties of Paper Caused by the Damage Mechanisms Present in the Fibre Structure</a></li>
<li><a href="#p453">Strong Coupling of the Fast Multilevel Multipole Boundary Element Method with the Finite Element Method for Vibroacoustic Problems</a></li>
<li><a href="#p361">The Head Related Transfer Function Simulation by FEM/IEM and Reciprocal Theorem</a></li>
<li><a href="#p598">Study on Acoustic Scattering by Hard Plane and Soft Surface Multi-Cracked Plate</a></li>
<li><a href="#p83">Partition Hole Design for Maximizing or Minimizing the Fundamental Eigenfrequency of a Double Cavity by Topology Optimization</a></li>
<li><a href="#p452">Comparison of Higher-Order Numerical Schemes and Several Filtering Methods Applied to Navier-Stokes Equations with Applications to Computational Acoustics</a></li>
<li><a href="#p287">An Acoustic Finite Element Including Viscothermal Effects</a></li>
<li><a href="#p125">Boundary Element Models of Horn Loaded Loudspeakers</a></li>
<li><a href="#p126">Derivative Free Optimisation in Engineering Acoustics</a></li>
<li><a href="#p30">A Numerical Study of Sound-Structure Interaction in a Duct Structure by the Acoustical Wave Propagator Method</a></li>
<li><a href="#p480">Graft of the Boundary Integral Method Onto the Image-Source Method for Vehicle Acoustics</a></li>
<li><a href="#p435">Benchmark Tests to Rank Software for Noise Prediction</a></li>
</ul>
<li>R-Condition monitoring and vibration analysis</li>
<ul>
<li><a href="#p3">Energy Consumption and Machinery Vibrations</a></li>
<li><a href="#p715">Gearbox Fault Detection by Motor Current Signature Analysis</a></li>
<li><a href="#p208">Spectral Analysis of Tapered Roller Bearing Vibration Using Inductive Modeling</a></li>
<li><a href="#p266">Vibration Event Detection: A Monitoring Method for Slow Speed Bearings</a></li>
<li><a href="#p265">Symmetric Wave Decomposition as a Means of Identifying the Number of Damaged Elements in a Slow Speed Bearing</a></li>
<li><a href="#p264">De-Convolution of Time-Series Data Using Translational Symmetry and Eigenstate Analysis</a></li>
<li><a href="#p263">Symmetry Methods Applied to the Condition-Monitoring of Slow Speed Slew Bearings</a></li>
<li><a href="#p771">Impact Mass Estimation for a Plate Type Structure by Using Smoothed Wigner-Ville Distribution</a></li>
<li><a href="#p716">Using Vibrational Properties of the Wheel to Identify Tyre - Road Friction</a></li>
<li><a href="#p335">Intellegent Two Wire Vibration Switch - New Class of Monitoring Device</a></li>
<li><a href="#p77">Chain Fault Detection of Escalator Using Handrail Vibration</a></li>
<li><a href="#p636">Spectrum Enhancement of Laser Vibrometer Signals Using a New Speckle Noise Reduction Technique and Angular Resampling</a></li>
<li><a href="#p4">Diesel Engine Fault Diagnosis Based on Vibration Monitoring and Artifical Neural Network</a></li>
<li><a href="#p702">Vibration Fatigue Design Methodology of a Large Scale Heavy Duty Robot</a></li>
<li><a href="#p742">Milling Cutting Tools Diagnosis with Higher Order Cyclic Spectra</a></li>
<li><a href="#p334">Investigating the Effects of the Static Cutting Force on the Chatter Vibrations of Milling Process</a></li>
<li><a href="#p36">Detection of Incipient Bearing Faults in Gas Turbine Engines</a></li>
<li><a href="#p584">Condition Monitoring and Vibration Testing of Centrifugal Pumps</a></li>
<li><a href="#p814">Machinery Vibration Analysis and Condition Monitoring: A Collaborative Approach</a></li>
<li><a href="#p411">Vibration Analysis of a Beam Carrying a Moving Mass</a></li>
<li><a href="#p601">Special Issues Related to Detection of Circumferential Crack at Different Orientations in Pipes by Vibration Method</a></li>
<li><a href="#p11">Response and Prediction of Dynamic Characteristics of Worn Rail Pads Under Static Preloads</a></li>
<li><a href="#p12">Artificial Shock Loading Quantities: Experimental Studies into the Influences of Railway Track Environments</a></li>
<li><a href="#p80">Vibrodiagnostic Method for Determination of the State of Wear of HCR Gear Sets</a></li>
<li><a href="#p695">Wear Oriented Strategy for Gearbox Remaining Lifetime Estimation</a></li>
<li><a href="#p692">Smart Condition Monitoring by Integration of Vibration, Oil and Wear Particle Analysis</a></li>
<li><a href="#p501">System Identification in Stochastic Domain Using System Output Only</a></li>
<li><a href="#p803">Time-Frequency Analysis of Acoustic Signals for Condition Monitoring of Fluid-Filled Pipelines</a></li>
<li><a href="#p249">Rolling Element Bearing Fault Diagnosis Based on Genetic Algorithms</a></li>
<li><a href="#p223">Rotor Crack Detection from Vibration Monitoring using a NARMAX Modelling Approach</a></li>
<li><a href="#p804">The Investigation of Submerged Vertical Pumps in a Power Plant Using Vibration Based Condition Monitoring Technique</a></li>
<li><a href="#p309">The Application Study of Force Limited Method in Vibration Tests</a></li>
</ul>
<li>R-Duct acoustics</li>
<ul>
<li><a href="#p374">A Modified Green’s Function for a Duct and its Application to the Calculation of the Sound Field Generated by a Piston</a></li>
<li><a href="#p164">Determination of Acoustic Properties for Open Duct Termination in Hot Jet Conditions Using FEM Simulation</a></li>
<li><a href="#p302">An Assessment of Alternative Sensor Technology for Transfer Matrix Measurements in Combustors</a></li>
<li><a href="#p678">Generating a “Silent” Flow of Air to Measure the Aerodynamic and Acoustical Performance of a Louvre Under Acoustical Laboratory Conditions</a></li>
<li><a href="#p776">Abnormal Resonance Noise of Exhaust Gas Passage in Urban Combined Power Plant</a></li>
</ul>
<li>R-Environmental and occupational noise</li>
<ul>
<li><a href="#p612">Recent Approaches to Environmental Noise Monitoring and Estimation of its Influence to the Health of Inhabitants</a></li>
<li><a href="#p749">Health and Safety Effects of Vibrations in Helicopters</a></li>
<li><a href="#p354">Regulating the Rapidly Developing Oil Sands Industry in Alberta and its Implications on Environmental Noise Monitoring and Assessment</a></li>
<li><a href="#p827">Optimising the Application of European Directive 2003/10/CE Performing Simple WED<sub>007</sub> Dosimetry</a></li>
<li><a href="#p813">The challenges of noise control in hospitals</a></li>
<li><a href="#p87">Noise Control Projects: the European Experience</a></li>
<li><a href="#p691">The Case for Spectral Baseline Noise Monitoring for Environmental Noise Assessment</a></li>
<li><a href="#p583">Experimental Outdoor Sound Propagation and ENM</a></li>
<li><a href="#p168">Noise in Hospital Areas - Measure and Evaluation</a></li>
<li><a href="#p826">No Worries - How to Handle Acoustical Planning Problems with Noise Calculation Software</a></li>
<li><a href="#p380">Acoustic Performance of First Generation Apartment Houses in Korea</a></li>
</ul>
<li>R-Human response to sound and vibration</li>
<ul>
<li><a href="#p127">Observation of Pure Frequencies in Bioresonance Vocal Sounds</a></li>
<li><a href="#p20">Effects of Temporarily Limited Noise Calming Periods During Sleep</a></li>
<li><a href="#p237">Cochlear Mechanics, the Acoustic Reflex and Noise Induced Hearing Loss</a></li>
<li><a href="#p553">Acute Effect of a Helicopter Flight on Cellular Tissue Biochemical Markers</a></li>
<li><a href="#p441">Correlation between SIL and SII in a Light Aircraft Cabin During Flight</a></li>
<li><a href="#p320">Ride Comfort Evaluation for the Korean Experimental High-Speed Train</a></li>
<li><a href="#p549">The Effects of Low-Frequency Vibrations on Control Profile of Blood</a></li>
</ul>
<li>R-Industrial and occupational noise</li>
<ul>
<li><a href="#p680">Dollars and dB. the Cost of Conservative Acoustics in Industrial Noise Control</a></li>
<li><a href="#p338">Noise in the Intensive Care Unit (ICU)</a></li>
<li><a href="#p643">Noise Control in Hydroelectric Stations</a></li>
<li><a href="#p113">The Mechanism of Noise Formation and Calculation of Noise Characteristics of Underexpanded Steam Jets</a></li>
</ul>
<li>R-Industrial noise sources and control</li>
<ul>
<li><a href="#p514">Development of a Silencer for Acoustic Enclosures</a></li>
</ul>
<li>R-Low-frequency noise and vibration</li>
<ul>
<li><a href="#p226">Simulation of Engine Vibration on Nonlinear Hydraulic Engine Mounts Through Full-Vehicle Model</a></li>
<li><a href="#p506">Response Analysis of Ship Structures Subjected to a Cluster of Impulsive Excitations</a></li>
<li><a href="#p504">Exposure of Timber Truck Drivers to Whole-Body Vibration and Noise</a></li>
<li><a href="#p384">Impact Property and Post Impact Vibration between Two Identical Spheres</a></li>
<li><a href="#p251">Theoretical and Numerical Study on Hydroelastic Vibration of Plate for Various Bounded Fluid Field</a></li>
<li><a href="#p777">Stationary Response of a Military Tracked Vehicle</a></li>
<li><a href="#p640">A Spectral Finite Element Model for Thin Plate Vibration</a></li>
<li><a href="#p275">Stochastic and Chaotic Analysis of Subharmonic Response of a Shallow Cable</a></li>
<li><a href="#p285">Comfort Analysis of Lightweight Floor System</a></li>
</ul>
<li>R-Machinery noise and vibration control</li>
<ul>
<li><a href="#p317">Minimisation of Noise and Vibration Level from a Steel Panel</a></li>
<li><a href="#p495">How to Predict the Vibration Effect Due to Machine Operation on its Surroundings</a></li>
<li><a href="#p188">Closed-Loop Feedback Model of Chatter in a Shaping Operation</a></li>
<li><a href="#p180">Analysis of High Longitudinal Vibration on a Diesel Generator Using Modern Analysis Tools</a></li>
<li><a href="#p185">River Pump Room Isolation from State Library</a></li>
<li><a href="#p775">Updating an Elastodynamic Model of Gear Pumps to Helical Gear Prototypes</a></li>
<li><a href="#p290">Influence of Design and Operational Parameters on the Dynamic Behaviour of Gear Pumps</a></li>
<li><a href="#p292">Which Are the Most Important Pressure Effects in Dynamic Analysis of Gear Pumps?</a></li>
<li><a href="#p26">Modeling of the Sound Transmission Loss of Leaks and Openings</a></li>
<li><a href="#p740">Noise Reduction of Personal Color Laser Printer</a></li>
<li><a href="#p25">Investigate the Noise Problems of Ball Screws With and Without Cage</a></li>
<li><a href="#p58">Noise Control on Backhoe Loaders by Coherence and Intensity Techniques</a></li>
<li><a href="#p68">Analysis of Vibratory Response and Noise Radiation of Engine Block Coupled with the Rotating Crankshaft and Gear Train System</a></li>
<li><a href="#p334">Investigating the Effects of the Static Cutting Force on the Chatter Vibrations of Milling Process</a></li>
<li><a href="#p96">Acoustical Treatment of Emergency Power Generator</a></li>
<li><a href="#p422">Numerical/Experimental Characterization of a Piezoelectric Driven Electromedical Device</a></li>
<li><a href="#p525">Structure-Borne Noise Generated by Vacuum Cleaner Suction Units</a></li>
<li><a href="#p128">Optimization of Sound Insulation in the New Generation of Washing Machines</a></li>
<li><a href="#p239">An Accurate Method of Knock Detection Using Wavelet Transform for Spark-Ignition (SI) Engine</a></li>
<li><a href="#p225">Active Control of Chatter Vibrations in a Turning Process Using an Adaptive FXLMS Algorithm</a></li>
<li><a href="#p439">Dynamics of Piezoceramics-Based Mass and Force Actuators for Rotating Machines</a></li>
<li><a href="#p564">The Design of Motor Brackets for the Reduction of Structure-Borne Noise in Package Air-Conditioners</a></li>
<li><a href="#p408">A Study of the Design of a Cantilever Type Multi-D.O.F. Dynamic Vibration Absorber for Micro Machine Tools</a></li>
<li><a href="#p261">Identification of Machine Tool Chatter for Milling Operations with Runout</a></li>
<li><a href="#p336">Investigation of Torsional Vibration Characteristics of Marine Diesel Engine Crankshaft System</a></li>
<li><a href="#p116">Shock Analysis of Propulsion Shaft of the Ship with Consideration of the Oil Film Force</a></li>
<li><a href="#p29">Powered Seat Adjuster Noise Characteristics and its Psychoacoustics Assessment</a></li>
<li><a href="#p587">Research on Dual-Shaker Sine Vibration Control</a></li>
<li><a href="#p757">Reduction of Noise and Vibration of Front Loading Washing Machine in Spin-Cycle</a></li>
</ul>
<li>R-Measurement techniques</li>
<ul>
<li><a href="#p394">Vibro-Acoustic Characterisation of a D.I. Diesel Engine by the Use of the Scanning Laser Vibrometer Technique</a></li>
<li><a href="#p247">Nonlinear Effects in Airborne Sound Insulation Measurement</a></li>
<li><a href="#p498">Experimental Comparison of PU Probes and Microphone Arrays Used in Impulse Acoustic Holography</a></li>
<li><a href="#p212">Analysis and Performance Monitoring of Electro Acoustic Systems</a></li>
<li><a href="#p729">A Method for Optimal Reconstruction of Velocity Response Using Experimental Displacement and Acceleration Signals</a></li>
<li><a href="#p769">An On-Line Monitoring Technique for a Pipe Thinning</a></li>
<li><a href="#p810">Experimental Identification of the Transfer Matrix of the Muffler</a></li>
<li><a href="#p196">Effect of Artificial Mouth Size on Speech Transmission Index</a></li>
<li><a href="#p291">Comparison of Speech Measurements in a Diffuse Space</a></li>
<li><a href="#p41">Investigation of Start-up Impact Characteristics of Liquid Rocket Engines</a></li>
<li><a href="#p413">A Numerical Study on Practical Measurement Method of Vibration Intensity in a Plate with Standing Wave</a></li>
<li><a href="#p624">Extraction of Wavenumbers and Amplitudes from Plate Vibration Measurements</a></li>
<li><a href="#p559">Measuring Wave Fronts of Inflating Airbags</a></li>
<li><a href="#p782">Laser Doppler Vibrometer for Measuring Small Amplitude of Vibration Using Synthetic Heterodyne Interferometry</a></li>
<li><a href="#p410">Modeling the Interaction of Guided Wave with the Welded Support in Pipes</a></li>
<li><a href="#p652">Using Hysteresis Loop and Torsional Shock Loading to Asses Damping and Efficiency of Cyclodrives</a></li>
<li><a href="#p32">Finite Periodic Structure of Beam for Low Frequency Structure-Borne Sound Attenuation</a></li>
<li><a href="#p387">Online Non-Contact Torsion Sensing Method Using Fiber Bragg Grating Sensors and Optical Coupling Method</a></li>
</ul>
<li>R-Modal analysis</li>
<ul>
<li><a href="#p370">Effect of Axial Force, Unbalance and Coupling Misalignment on Vibration of a Rotor Gas Turbine</a></li>
<li><a href="#p59">Vibration Analysis of Vibratory Gyros</a></li>
<li><a href="#p795">Frequency Response of Flat Post-Tensioned Concrete Floors: Frequency Coefficient-Root Function Method</a></li>
<li><a href="#p470">Operational Modal Analysis by Using Transmissibility Measurements with Changing Distributed Loads</a></li>
<li><a href="#p817">Influence of Stiffness and Mass Changes on Eigen Frequencies of Beam with Piezo Electric Patch</a></li>
<li><a href="#p508">Modal Identification of the Wet Modes of a Marine Structure</a></li>
<li><a href="#p342">New Strategies for Model Validation Using Modal Test Data</a></li>
<li><a href="#p754">An Investigation into the Linearity of the Sydney Olympic Stadium</a></li>
<li><a href="#p108">Development of an in-Service Dynamic Model of a Double Deck Passenger Train</a></li>
<li><a href="#p767">Structural Stress Analysis Undergoing Harmonic Excitation Using Modal Theory</a></li>
<li><a href="#p198">Optimum Design of Vibration Absorber with Variable Position for an Euler-Bernoulli Beam Under Moving Point Excitation</a></li>
<li><a href="#p446">Operational Structural Transfer Path Analysis</a></li>
<li><a href="#p289">Experimental Evaluation of the Modal Damping of Automotive Components with Different Boundary Conditions</a></li>
<li><a href="#p120">Investigation of the Dynamic Properties of a Boring Bar Concerning Different Boundary Conditions</a></li>
<li><a href="#p279">Energetic Characteristics of Vibration Loads on a Mechanical Object</a></li>
<li><a href="#p801">Modal Analysis of Asynchronous Motor Vibration</a></li>
<li><a href="#p93">Modal Analysis of Large Structures Submerged in a Fluid</a></li>
<li><a href="#p505">Study on the Dynamic Tilt Characteristics of Optical Pickup Actuators Considering Electromagnetic Nonlinearities Using Coupled-Field Analysis</a></li>
<li><a href="#p352">Shimmy Evaluation Using Theoretical Multibody Model and Experimental Techniques</a></li>
<li><a href="#p276">System Reduction in Nonlinear Multibody Dynamics of Wind Turbines</a></li>
<li><a href="#p19">A Method of Measuring the Axial Elastic Modulus of a Sandwich Cylinder Based on Modal Testing</a></li>
<li><a href="#p675">Comparison of FE and Modal Models in Model Updating Methods</a></li>
<li><a href="#p820">The Mass-Loading Effect of Accelerometers on MAC Criterion</a></li>
<li><a href="#p572">Transient Vibration Analysis for Generating Low Electrical Power</a></li>
<li><a href="#p531">Operational Modal Analysis in Presence of Unknown Varying Harmonic Forces</a></li>
<li><a href="#p312">Dynamic Response of Box-Type Sonar Structure</a></li>
<li><a href="#p38">Influence of a Rectangular Plate Inhomogeinity on Natural Frequencies of a Clamped Rectangular Plate</a></li>
<li><a href="#p667">Vibration Analysis of Mindlin’s Sandwich Plate (FSDT) Under Random Excitation</a></li>
<li><a href="#p357">Detection of Damage Location in Structures Using Operating Deflection Shape</a></li>
<li><a href="#p187">Eigenfrequency Computation by the Finite Sine Transform Method on a Rectangular Plate Carrying Arbitrary Number of Concentrated Masses and Springs</a></li>
<li><a href="#p200">Propagation Phase Representation in 3D Space Using Poles and Zeros in Complex Frequency Plane</a></li>
</ul>
<li>R-Noise control elements</li>
<ul>
<li><a href="#p102">Dynamic Response Analysis of Rectangular Perforated Plates with Varying Sizes of Circular Perforation Holes</a></li>
<li><a href="#p821">Recent developments in applications of microperforated panel absorbers</a></li>
<li><a href="#p825">Effectiveness of Noise Barriers Tilted Towards the Traffic Way Over Bridges</a></li>
<li><a href="#p343">Acoustic Barrier for Transformer Noise</a></li>
<li><a href="#p570">Study the Panel and Helmholtz Resonances of a Micro-Perforated Absorber</a></li>
</ul>
<li>R-Noise source identification</li>
<ul>
<li><a href="#p274">Localization and Identification of Persons and Ambient Noise Sources Via Acoustic Scene Analysis</a></li>
<li><a href="#p502">Noise Source Identification in Magnetic Field Using SVDD (Support Vector Data Description)</a></li>
<li><a href="#p726">Extending the Usability of Near-Field Acoustic Holography and Beamforming by Using Focalization</a></li>
<li><a href="#p322">Sound Propagation Through a Heat-Exchanger Tubes Array in Power Boiles</a></li>
<li><a href="#p375">Ranking of Partial Noise Sources and Noise Control Measures</a></li>
<li><a href="#p705">Neural Techniques for Source Identification</a></li>
<li><a href="#p310">Microphone Array Beamforming and Methods for the Reconstruction of Ducted Acoustic Sources</a></li>
<li><a href="#p784">Acoustic Antenna Design General Guidelines for Beamforming Noise Source Localization</a></li>
</ul>
<li>R-Outdoor sound propagation</li>
<ul>
<li><a href="#p465">Noise Evaluation in a Race-Track: Measurements, Software Analyses and Need of Continuous Monitoring. Comparison Among the Results.</a></li>
<li><a href="#p781">Traffic Noise Abatement by Means of Acoustical Barriers: An Example of Reliability of Prediction Models with Different Kind of Barriers and Different Context</a></li>
</ul>
<li>R-Ship Vibrations</li>
<ul>
<li><a href="#p281">Local Ship Vibrations - A Methodology for Their Evaluation and Control from the Early Design Phase</a></li>
</ul>
<li>R-Signal processing</li>
<ul>
<li><a href="#p594">A Cepstrum-Based Method for Remote Train Detection</a></li>
<li><a href="#p728">Binaural Cepstrum Coefficient and its Application to Ground Target Recognition</a></li>
<li><a href="#p450">Contrast Function Based Fourth-Order Statistics and Wiener Filtering for Separation of Convolutive Mixtures</a></li>
<li><a href="#p526">Limitations and Error Analysis of Spherical Microphone Arrays</a></li>
<li><a href="#p778">Application of Cepstrum Analysis in Speech Coding</a></li>
</ul>
<li>R-Sound intensity</li>
<li>R-Sound sources</li>
<ul>
<li><a href="#p510">Non-Uniform, Harmonic, Edge Excitation of a Waveguide</a></li>
<li><a href="#p176">Linear Sources with Non-Linear Distribution of Sound Energy</a></li>
<li><a href="#p616">Direct Algebraic Method for Sound Source Localization with Finest Resolution Both in Time and Frequency</a></li>
</ul>
<li>R-Soundscapes</li>
<ul>
<li><a href="#p5">Areas of High Acoustic Quality: Soundscape Planning</a></li>
<li><a href="#p455">Change in Quality of Environmental Sound in the Autumn</a></li>
</ul>
<li>R-Transducers</li>
<ul>
<li><a href="#p193">Analysis, Design and Fabrication of MEMS Capacitive Microphones</a></li>
</ul>
<li>R-Transportation noise</li>
<ul>
<li><a href="#p709">Urban Transport and Noise Impact: A Preventive Applied Research to Control Noise Impact of New Road to be Build in Catania Province</a></li>
<li><a href="#p673">Frequency Dependence in Tyre-Road Emissions Using the Close Proximity Method</a></li>
<li><a href="#p499">Repeatability of CPX Tyre/Road Noise Measurements</a></li>
<li><a href="#p173">Modified Tire-Pavement Noise Measurement Techniques for Noise Assessment on Asphalt-Rubber Roads</a></li>
<li><a href="#p273">Noise Source Identification of Korean High Speed Train</a></li>
<li><a href="#p720">Regulation of Heavy Vehicle Engine Brake Noise in Australia</a></li>
<li><a href="#p503">Novelty Detection of Radar Signal Using Support Vector Data Description</a></li>
<li><a href="#p655">The Contribution of the Individual Sound Source Generated from Shinkansen Vehicles</a></li>
<li><a href="#p798">Acoustic Properties of Sound Barriers</a></li>
<li><a href="#p181">A Model of the Wear Due to the Rolling Contact of a Wheel Over a General Rail Profile</a></li>
<li><a href="#p182">A Case Study on the Effect of Speed Variation on the Growth of Wear-Type Rail Corrugation </a></li>
<li><a href="#p653">Comparing Weekly and Weekday Averaged Traffic Data When Modelling Traffic Noise</a></li>
<li><a href="#p2">A Recent Investigation into the Influences of Some Australian Asphalt Pavement Surfaces on Road Traffic Noise</a></li>
<li><a href="#p321">Characteristics of Aerodynamic Noise from the Inter-Coach Spacing of a High-Speed Train</a></li>
<li><a href="#p732">Noise Characteristics of an Exposed Aggregate Cement Concrete Surface</a></li>
<li><a href="#p421">A Preliminary Study of Noise in a Tunnel Due to a Moving Train</a></li>
<li><a href="#p669">The Study of Vertical Distribution of Urban Road Traffic Noise</a></li>
</ul>
<li>R-Ultrasound</li>
<ul>
<li><a href="#p642">Ultrasound Piezoceramic Transducer for Underwater Acoustics in Sonochemistry</a></li>
<li><a href="#p738">Removal of Dust on Flat Board by Device of Focusing Ultrasonic Waves</a></li>
</ul>
<li>R-Vibroacoustics</li>
<ul>
<li><a href="#p349">Design Sensitivity Analysis of Zwicker’s Loudness Using the Adjoint Variable Method</a></li>
<li><a href="#p811">A Comparison of Structural-Acoustic Coupled Reduced Order Models (ROMS): Modal Coupling and Implicit Moment Matching Via Arnoldi</a></li>
</ul>
<li>S-Acoustic materials and their characterisation</li>
<ul>
<li><a href="#p184">Accurate Measurement of Small Absorption Coefficients</a></li>
<li><a href="#p92">Influences of Compression Effect on Sound Absorption Characteristics</a></li>
<li><a href="#p386">Acoustical Properties of Polyurethane Open Cells Materials: Experimental Investigation and Theoretical Models</a></li>
<li><a href="#p160">Standardization of Road Traffic Noise Map in Korea</a></li>
<li><a href="#p313">Development of a Semi-Empirical Model of Mechanical Hysteresis for Sandwich Composite Materials, and System Identification Using Heuristic Optimization Methods</a></li>
<li><a href="#p746">Estimation of Sound Absorption Coefficients of Porous Materials</a></li>
<li><a href="#p385">Frequency Dependent Tortuosity Measurement by Means of Ultrasonic Tests</a></li>
<li><a href="#p191">Performance of Perforated Facing Absorbers</a></li>
<li><a href="#p546">Stability of Sound Speed and Attenuation Identified in Material Samples</a></li>
</ul>
<li>S-Active control of sound</li>
<ul>
<li><a href="#p142">Active Noise Control on High Frequency Narrow Band Dental Drill Noise: Preliminary Results</a></li>
<li><a href="#p447">Nonlinear Secondary Path Model Identification</a></li>
<li><a href="#p401">Active Control of Vibration and Radiated Sound of a Submerged Circular Plate</a></li>
<li><a href="#p701">A Brief Review of Active Control of Environmental Noise and its Applications</a></li>
<li><a href="#p458">Suboptimal Multichannel Adaptive ANC System</a></li>
<li><a href="#p209">Feedback Supervising Feedforward Minimum-Variance Control of Acoustic Noise</a></li>
<li><a href="#p391">Robust Control Design for Active Noise Control Systems of Ducts with a Ventilation System Using a Pair of Loudspeakers</a></li>
</ul>
<li>S-Active noise and vibration control in practical system implementations</li>
<ul>
<li><a href="#p659">Noise Suppression Using Active Noise Control and Masking</a></li>
<li><a href="#p220">The Improved Active Control Algorithm for Marine Diesel Two-Stage Vibration Isolation System</a></li>
<li><a href="#p339">Robust Pole Placement for Active Vibration Control of Seismic-Excited Buildings</a></li>
<li><a href="#p16">Active Control for Vibroprotection of Operators of Technological Machines</a></li>
<li><a href="#p788">Simultaneous Optimization of Structure Control of Smart Tensegrity Structures</a></li>
<li><a href="#p490">A Feedforward Active Noise Control System for Ducts Using a Passive Silencer to Reduce Acoustic Feedback</a></li>
<li><a href="#p366">Active Vibration Control of Hard-Disk Drives Using PZT Actuated Suspension Systems</a></li>
<li><a href="#p460">Position Dependent Linearized Elastic Models of Parallel Robot Systems with Embedded Smart Devices for Vibration Suppression Control Algorithms</a></li>
<li><a href="#p805">Experimental Modal Analysis of an Actively Controlled Scaled Metro Vehicle Car Body</a></li>
<li><a href="#p792">Simulation of a Combined Switched and Inductive Shunt Control Acting on a 2D Structure</a></li>
<li><a href="#p683">Dynamic Modelling and Input Shaping Control for Positioning Stage</a></li>
<li><a href="#p255">Initial Experiments with a Finite Element Model of an Active Boring Bar</a></li>
</ul>
<li>S-Advanced multi-objective damping for composite structures</li>
<ul>
<li><a href="#p199">Experimental Identification of Fractional-Derivative Parameters of a Damping Material Using the Optimization Technique</a></li>
</ul>
<li>S-Advanced signal processing on sound and vibration</li>
<ul>
<li><a href="#p363">State Estimation Method for Sound Environment System with Unknown Structure and its Application to Evaluation of Road Traffic Noise</a></li>
<li><a href="#p595">High Quality Recording Through Microphone Array in Noisy and Reverberant Environment</a></li>
<li><a href="#p9">In-Car Speech Enhancement Using Ensemble Empirical Mode Decomposition</a></li>
<li><a href="#p230">Determination of Mechanical Properties of a Nonuniform Beam Using the Measurement of the Excited Longitudinal Elastic Vibrations</a></li>
<li><a href="#p205">A Proposal to Hi-Tech Pollution Based on the Criterion of “Relationism-First” - A Principle Experiment for the Relation between Acoustic and EM Fields Around VDT</a></li>
<li><a href="#p766">Shock Spectrum Calculation of Structural Response to UNDEX</a></li>
</ul>
<li>S-Aeroacoustics</li>
<ul>
<li><a href="#p666">A Numerical Study of Fluid Flow Past a Circular Cylinder at Re = 3900 and a Practical Approach to Noise Prediction</a></li>
<li><a href="#p759">Demonstration of Inadequacy of Ffowcs Williams and Hawkings Equation of Aeroacoustics by Thought Experiments</a></li>
<li><a href="#p558">A 3D Numerical Method to Study Poroelastic Liners with Mean Flow</a></li>
<li><a href="#p117">Computation of Indirect Combustion Noise by a CAA-Method</a></li>
<li><a href="#p260">Validation of an Innovative Hybrid Method for the Prediction of Noise Generated by Confined Flows</a></li>
<li><a href="#p333">Noise Prediction of a Serrated Nozzle Using a Hybrid Approach</a></li>
<li><a href="#p407">Applications of a Finite-Element Mode-Matching Method to Acoustic Design of the Bypass Duct of Turbofan Engines</a></li>
<li><a href="#p432">A Selective Overview of High-Order Finite Difference Schemes for Aeroacoustic Applications</a></li>
<li><a href="#p183">Critical Issues in Experimental Jet Aeroacoustics</a></li>
<li><a href="#p369">Diagnostics of Aero-Acoustic Performance of Forward Slanted Perforated Tube</a></li>
<li><a href="#p204">Noise Reduction of Handheld Vacuum Cleaners According to Geometric Optimization of Air Passages</a></li>
<li><a href="#p282">Effect of Boundary Conditions and Source Truncation in the Prediction of Flow-Generated Sound</a></li>
<li><a href="#p819">Predicting and reducing aircraft noise</a></li>
<li><a href="#p588">Stepwise Air Flow in the Gravity Draught Aeroacoustic Tunnel</a></li>
<li><a href="#p417">Predictions of Fan Broadband Noise Due to Rotor-Stator Interaction</a></li>
</ul>
<li>S-Architectural acoustics</li>
<ul>
<li><a href="#p423">A Simple Formula for Predicting the Reverberation Time in Long Enclosures</a></li>
<li><a href="#p631">Implementation of the Uniform Theory of Diffraction in the Phased Beam Tracing Method</a></li>
<li><a href="#p112">Effects of Reverberation Time and Sound Source Characteristic to Auditory Localization in an Indoor Sound Field</a></li>
<li><a href="#p203">A Review of Residential Balconies with Road Traffic Noise</a></li>
<li><a href="#p625">Research of Auralization in Small Enclosures</a></li>
<li><a href="#p621">Acoustic Tests on Original Concrete and Inert Mixture Materials</a></li>
<li><a href="#p28">Acoustics in Large Atrium Spaces</a></li>
<li><a href="#p426">Transmission of Sound in a Long Enclosure with a “T” Intersection</a></li>
<li><a href="#p440">Time Domain Large-Scale Finite Element Sound Field Analysis of a Multi-Purpose Hall</a></li>
</ul>
<li>S-Combustion noise and thermo-acoustics</li>
<ul>
<li><a href="#p155">Numerical Study of Structural Vibration Induced by Combustion Noise - One Way Interaction</a></li>
<li><a href="#p215">Overview of Different Approaches for Active Control of Combustion Instabilities</a></li>
<li><a href="#p235">Active Control of Combustion Instability Using Pilot and Premix Fuel Modulation</a></li>
<li><a href="#p420">Application of Modal Parameter Derivation in Active Suppression of Thermo Acoustic Instabilities</a></li>
<li><a href="#p214">The Acoustic Wave Propagation Equation in a Turbulent Combusting Flow</a></li>
<li><a href="#p121">An Asymptotically Motivated Hyrodynamic-Acoustic Two-Way Coupling for Modeling Thermoacoustic Instabilities in a Rijke Tube</a></li>
<li><a href="#p301">Passive Control of Combustion Induced Noise in an Auxiliary Bus Heating System</a></li>
<li><a href="#p711">The Rijke Tube: Green’s Function Approach in the Time and Frequency Domain</a></li>
<li><a href="#p141">Experimental Validation of Linear Analysis in Premixed Combustors Supported by Active Control</a></li>
<li><a href="#p569">Sound Propagation in a Region of Hot Gas Using the DRBEM</a></li>
<li><a href="#p110">Experimental Study of the Flame Cone Kinematics of Acoustically Perturbed Premixed Laminar Bunsen Flames</a></li>
</ul>
<li>S-Education of acoustics and vibration</li>
<ul>
<li><a href="#p169">Succesful Teaching of Experimental Vibration Research</a></li>
<li><a href="#p523">A Tempus Experience: New Curriculum in Sound and Vibration Control in Egypt</a></li>
</ul>
<li>S-Elastodynamics of periodic structures and composites</li>
<ul>
<li><a href="#p256">Flexural Vibration Band Gaps in Periodic Pipe System Conveying Fluid</a></li>
<li><a href="#p353">Non-Periodic Locally Resonant Sonic Materials</a></li>
<li><a href="#p329">Wave Propagation in Thin Orthotropic Media</a></li>
<li><a href="#p257">Directional Propagation Characteristics of Flexural Wave in Two-Dimensional Periodic Grid-Like Plate Structures</a></li>
<li><a href="#p800">Finite Element Modeling of Multi-Layer Composite Plates with Internal Delamination</a></li>
<li><a href="#p719">Vibration Attenuation in a Periodic Rotating Timoshenko Beam</a></li>
<li><a href="#p148">Vibration of Elastic Rings Excited by Periodically-Spaced Moving Springs</a></li>
<li><a href="#p250">Acoustic Wave Propagation Modeling for Periodic Structures as Applied to Anechoic Coating Design</a></li>
<li><a href="#p307">Experimental Studies on Two-Dimensional Acoustic Defect-Mode Waveguides in a Sonic/Phononic Crystal</a></li>
<li><a href="#p242">An Algorithm for Studying Wave Propagation in Phononic Crystals Composed of Viscoelastic Material</a></li>
</ul>
<li>S-Environmental noise and vibration from metro, tramways and highway transportation</li>
<ul>
<li><a href="#p639">The Affect of the Thessaloniki Ring Road Traffic Noise Emission on Hospitalized Patients in Papageorgiou Hospital</a></li>
<li><a href="#p443">Influence of Traffic Sound Parameters on the Reading Performance in Elementary School Children</a></li>
<li><a href="#p604">Vibration from Railways: Can we Achieve Better Than ±10 dB Prediction Accuracy?</a></li>
<li><a href="#p578">Environmental Effects from Vibration Emitted from the Operation of Urban Highways: A Measurement Campaign at Athens Ring Motorway Network</a></li>
<li><a href="#p579">Occupational Noise Vibration & Air Pollutants Fluctuation Inside the Toll Booths in the Athens Ring Motorway Network: “Attiki Odos”</a></li>
<li><a href="#p638">Environmental Noise Investigation Procedure in the Urban Road Network in Malta</a></li>
<li><a href="#p481">The PiP Model, a Software Application for Calculating Vibration from Undergrond Railways</a></li>
<li><a href="#p544">Modelling of Floating-Slab Tracks with Discontinuous Slabs in Underground Railway Tunnels</a></li>
</ul>
<li>S-Flow induced noise and structure-acoustic coupling</li>
<ul>
<li><a href="#p713">Free Vibration of Vertical Pump</a></li>
<li><a href="#p823">Eigenvalue Variation of Fuel Rod Exposed to Uniform Axial Flow</a></li>
<li><a href="#p412">Using Statistical Methods to Predict Induced Sound and Vibration in Aerospace and Automotive Applications</a></li>
<li><a href="#p566">Transient Dynamic Responses of an Internal Liquid-LNG Tank-Sea Water Interaction System Excited by Waves and Earthquake Loads</a></li>
</ul>
<li>S-GIS application in noise assessment</li>
<ul>
<li><a href="#p543">Dissemination of Predicted Noise Levels in a 3D Visualised Interactive Environment Through the Internet for 3D EIA and Planning Projects (Hong Kong)</a></li>
<li><a href="#p79">How Territory-Wide GIS-Based Road Traffic Noise Assessment Tools Facilitate Decision Making in Strategic Level Environmental Assessment</a></li>
<li><a href="#p78">Practical Experience in Engaging the Public Through Interactive 3D Technology in Retrofitting Barrier Projects on Existing Roads</a></li>
<li><a href="#p794">Technology Driven Solutions for the Quantification of Urban Road Noise</a></li>
<li><a href="#p54">State-Wide Road Noise Mapping of Queensland, Australia</a></li>
<li><a href="#p658">GIS for the Evaluation of Road Traffic Noise at Areas Facing Roads in Japan - Key Functions Including Estimation of the Numbers of Residents in Buildings</a></li>
<li><a href="#p799">Standardization of Road Traffic Noise Map in Korea</a></li>
<li><a href="#p396">Noise Mapping - What for and How to be More Effective?</a></li>
<li><a href="#p676">An Overview of the Impact of Source Data Accuracy Variations on the Overall Accuracy of Noise Maps</a></li>
</ul>
<li>S-Information environmental systems</li>
<li>S-Intelligent methods of active noise and vibration control</li>
<ul>
<li><a href="#p764">Buckling and Vibration Analysis of Magnetoelectroelastic Beam</a></li>
<li><a href="#p243">Linear Modelling of Magneto-Rheological Dampers Using Hybrid Intelligence Technique</a></li>
<li><a href="#p694">Design of Semi-Active Tuned Mass Damper for Controlling Seismically Induced Responses of Elastic and Inelastic Structures</a></li>
</ul>
<li>S-Microphone array applications</li>
<ul>
<li><a href="#p708">Localisation of Coherent Sound Sources Using a Microphone Array</a></li>
<li><a href="#p571">Loud: A 1020-Node Microphone Array and Acoustic Beamformer</a></li>
<li><a href="#p802">An Investigation into the Fault Detection of Machines Based on Acoustic Array Systems</a></li>
<li><a href="#p515">One Sensor Microphone Array Application in Source Localization</a></li>
<li><a href="#p661">Optimal Circular Array Configuration</a></li>
</ul>
<li>S-Mid and high frequency methods</li>
<ul>
<li><a href="#p534">Using the Hybrid FE-SEA Method to Predict Structure-Borne Noise Transmission in a Trimmed Automotive Vehicle</a></li>
<li><a href="#p789">Efficient Wave Based Models for Acoustic Scattering and Transmission Problems Using Point Source and Planewave Excitation</a></li>
<li><a href="#p428">On the Use of a High-Order Finite Element - Wave Based Method for Interior Acoustic Cavity Analysis</a></li>
<li><a href="#p487">Application of Modal Model Reduction for Hybrid Structural Finite Element - Acoustic Wave Based Models</a></li>
<li><a href="#p397">Wave-Based Discontinuous Galerkin Methods in the Frequency Domain with Application to Flow Acoustics</a></li>
<li><a href="#p685">Natural Frequency Statistics of Plates with Bounded Uncertain Properties Using Interval Analysis</a></li>
<li><a href="#p462">Efficient Numerical Models for Investigating Statistics of Random Dynamic Systems</a></li>
<li><a href="#p735">Modelling Complicated Systems with Partly Unknown Dynamic Properties as “Structural Fuzzy”</a></li>
<li><a href="#p671">High Frequency Approximations for Treating Acoustic Radiation or Scattering Problems with the Boundary Element Method</a></li>
<li><a href="#p149">Physics-Based Numerical Method for Analyzing Mid-Frequency Acoustic Radiation</a></li>
<li><a href="#p672">Generation and Validation of Acoustic 3D WBT Models of a SUV Driver Compartment from SEA Models</a></li>
<li><a href="#p535">Modeling Methods for Vibro-Acoustic Analysis of Commercial Aircrafts</a></li>
<li><a href="#p284">The Coupling of a Hearing AID Loudspeaker Membrane to Visco-Thermal Air Layers</a></li>
</ul>
<li>S-Muffler acoustics</li>
<ul>
<li><a href="#p637">Prediction of Breakout Noise from End Plate of an Expansion Chamber Using Coupled FE/BE Analysis</a></li>
<li><a href="#p201">Recent Advances in IC-Engine Acoustic Source Characterisation</a></li>
<li><a href="#p270">FRITAmuff: A Comprehensive Platform for Prediction of Un-Muffled and Muffled Exhaust Noise of IC Engines</a></li>
<li><a href="#p482">Sound Propagation in Narrow Channels with Arbitrary Cross Sections and Superimposed Mean Flow with Application to Charge Air Coolers</a></li>
<li><a href="#p797">Transfer Matrix Method for Dual-Chamber Mufflers</a></li>
<li><a href="#p586">One Design of a Silencer for Attenuating Fan Noise</a></li>
<li><a href="#p219">Study on the Simulation Design Method About Exhaust Muffler of Vehicle</a></li>
<li><a href="#p233">Application of Dual Reciprocity Boundary Element Method to Predict Acoustic Attenuation Characteristics of Silencers with Complex Flow</a></li>
</ul>
<li>S-Musical acoustics</li>
<ul>
<li><a href="#p179">Fractional Fourier Transforms for Spectral Analysis of Music Signals</a></li>
<li><a href="#p53">Wavelet Design for Music Perception Applied to Indian Classical Music</a></li>
<li><a href="#p608">Towards a Music Synthesizer Controlled by Timbral Adjectives</a></li>
<li><a href="#p756">Nonlinear Vibration Analysis in Acoustics</a></li>
<li><a href="#p686">A Study of Input Mobility Functions at a Violin’s Bridge</a></li>
<li><a href="#p628">The ‘Didjeriduo’: Musical Implications of a Three-Port Branched Duct</a></li>
<li><a href="#p248">Geometric Shape Identification for Multi-Mode Tuning of Percussion Instrument Bars</a></li>
<li><a href="#p565">Experimental Study of the Flow-Excited Acoustical Lock-in in a Corrugated Pipe</a></li>
</ul>
<li>S-Nearfield acoustic holography</li>
<ul>
<li><a href="#p632">An Investigation on the Sensor Proximity Effect in the BEM- Based NAH</a></li>
<li><a href="#p791">Acoustic Modelling of Machines Using the Inversion Method</a></li>
<li><a href="#p747">Application of Diagnostic Techniques in Improving Vibration and Acoustic Prediction</a></li>
<li><a href="#p741">Weighted Statistically Optimised Near Field Acoustic Holography with Pressure-Velocity Probes</a></li>
<li><a href="#p60">Research on the Theories of BEM Based Cyclostationary Near Field Acoustic Holography</a></li>
<li><a href="#p785">Plate Moduli Estimation Using Nearfield Acoustic Holography Techniques</a></li>
<li><a href="#p815">ACOUSTIC HOLOGRAPHY BASED ON THE INVERSE-BEM FOR
THE SOURCE IDENTIFICATION OF MACHINERY NOISE</a></li>
<li><a href="#p340">Experimental Application of High Precision K-Space Filters and Stopping Rules for Fully Automated PNAH</a></li>
<li><a href="#p464">Acoustic Holography and Complementary Boundary Conditions</a></li>
</ul>
<li>S-Noise and vibration in reciprocating and rotary compressors</li>
<ul>
<li><a href="#p153">Modified General Transfer Matrix Method for Linear Rotor Bearing Systems</a></li>
<li><a href="#p684">Noise and Vibration of Positive Displacement Compressors - A Review</a></li>
<li><a href="#p641">Noise Reduction of a Reciprocating Compressor by Adding a Resonator in Suction Path of Refrigerant</a></li>
</ul>
<li>S-Noise and vibration in space vehicles</li>
<ul>
<li><a href="#p516">Stiffeners Effect on Sound Transmission Through a Thin Plate Excited by a Turbulent Boundary Layer (Corcos Model) - Comparison with a Diffuse Sound Field</a></li>
<li><a href="#p395">Sound Reduction by Using Acoustic Resonators for Payload Fairing of Small Launch Vehicle</a></li>
</ul>
<li>S-Noise in cities</li>
<ul>
<li><a href="#p679">A Survey on the Control of Environmental Noise Ingress into Residential Apartment Buildings</a></li>
<li><a href="#p132">The Acoustic Characterization of the Urban Territory with Continuous Cycle Producing Settlements</a></li>
<li><a href="#p484">Analysis and Evaluation of Environmental Noise Conditions in Two Different Areas in Mexico City</a></li>
<li><a href="#p773">On Annoying Sounds Generated as Byproducts of ‘Good Intentions’</a></li>
<li><a href="#p493">Management of Environmental Noise - Cracow Example</a></li>
<li><a href="#p392">Quiet City - A European Project to Support Cities in Noise Mitigation</a></li>
</ul>
<li>S-Noise, vibration, harshness (NVH)</li>
<ul>
<li><a href="#p347">Brake Noise in Practice</a></li>
<li><a href="#p211">Disc Brake Squeal: Progress and Challenges</a></li>
<li><a href="#p192">One-Dimensional Topology Optimization for Transmission Loss Maximization of Multi-Layered Acoustical Foams</a></li>
<li><a href="#p50">Questionnaire-Based Survey on Drivers’ Noise and Vibration Discomfort</a></li>
<li><a href="#p51">Identification of Vehicle Interior Noise Sources Using Vibro-Acoustic Spectral Analysis Method</a></li>
<li><a href="#p593">Evaluation of Enhancement of Sound Quality of Axle Gear Based on Artificial Neural Network</a></li>
<li><a href="#p532">Integration of Sub-Systems on Vehicles</a></li>
</ul>
<li>S-Nonlinear acoustics and vibration</li>
<ul>
<li><a href="#p190">Characterization of Variable Material Properties by Nonlinear Acoustic Techniques</a></li>
<li><a href="#p703">Simplifications and Solutions of Diffraction Functions in Nonlinear Acoustic Parameter Measurement</a></li>
<li><a href="#p725">Modelling and Simulation of Ultrasound Non Linearities Measurement for Biological Mediums</a></li>
<li><a href="#p172">A Center Manifold Algorithm for Nonlinear Dynamic Systems with Time-Delay and Parametric Excitation</a></li>
<li><a href="#p429">Sometimes Digital Control Leads to Chaos</a></li>
<li><a href="#p64">An Analytical Model for Drillstring Axial Vibration</a></li>
<li><a href="#p24">Limit-Cycle Oscillation of Shape Memory Alloy Hybrid Composite Plates at Elevated Temperatures</a></li>
<li><a href="#p17">Identifying Chaotic Dynamics in a Flying Vibratory System</a></li>
<li><a href="#p654">Study on Mechanized Mathematics Modelling for 200 MW Turbo-Generator System</a></li>
<li><a href="#p809">Rectifications of Parametric Instability Due to Asymmetry of Rotating Shaft</a></li>
<li><a href="#p89">Theoretical Research Regarding Any Stability Theorems with Applications</a></li>
<li><a href="#p101">Free Vibrations of the Systems of Rigid Bodies Coupled by Elastic Bars</a></li>
<li><a href="#p62">Behaviour of Ultrasonic Wave Velocities in Materials Under Elastic Thermo Mechanical Effect</a></li>
<li><a href="#p171">Static Output Feedback Control for Non-Linear Flutter and Limit Cycle Oscillation</a></li>
<li><a href="#p70">Phase Change Analysis of Planar and Nonplanar Vibration in One-to-One Resonance of Nonlinear Cantilever Beam</a></li>
<li><a href="#p99">A Non-Linear Model for Studying the Motion of a Human Body</a></li>
<li><a href="#p100">Non-Linear Aspects of Human Body’s Motion in Car Crash</a></li>
<li><a href="#p262">Bearing Profile and Misalignment Effects on the Vibration Behaviour of Rotating Machinery</a></li>
<li><a href="#p138">Non Linear Response of Beams Using Finite Element Method with Symplectic Integration Scheme</a></li>
<li><a href="#p319">Numerical Simulation of Nonlinear Sound Wave Propagation Using CIP Method</a></li>
<li><a href="#p40">Therapeutic High Intensity Focused Ultrasound Fields (HIFU): Acoustic Characterization And Nonlinear Mechanics Of Heating</a></li>
<li><a href="#p231">The Analytical Calculations of the Parameters of the Fluctuations of the Ballistic Missiles</a></li>
<li><a href="#p84">Gauge Invariance Approach to Acoustic Fields</a></li>
<li><a href="#p85">Vector Theory of Ultrasonic Imaging</a></li>
<li><a href="#p618">Generalisation of Veselago’s Negative Refraction Theory Using Symmetries</a></li>
<li><a href="#p240">Analysis of Golf Ball Spin Mechanism at Impact by FEM</a></li>
<li><a href="#p649">Design of a Hula-Hoop Energy-Harvest Device Paper </a></li>
<li><a href="#p303">Effects of Landing Gear Nonlinearities on Ground Resonance of Helicopter</a></li>
<li><a href="#p175">A Study on Response Analysis of Pneumatic Vibration Isolation Table Loaded by Transient Movements of Carriage on it</a></li>
</ul>
<li>S-Passive techniques in vibrations and acoustics attenuation</li>
<ul>
<li><a href="#p660">Passive Noise Control of a Burner-Combustor System of a Turbo-Fan Engine</a></li>
<li><a href="#p298">Nodalization of Isolator for Floating Floor Design</a></li>
<li><a href="#p299">The Effects of Local Modes on Vibration Reduction of Building Isolation</a></li>
<li><a href="#p14">Theoretical and Experimental Results of the Transmission Loss of a Plate with Discrete Masses Attached</a></li>
<li><a href="#p520">Design Analysis of a Rubber Mount System for a Push-Type Centrifuge</a></li>
<li><a href="#p325">The Dynamic Characteristics of SMA Helical Spring in Axial Vibratory Motion</a></li>
<li><a href="#p405">Noise Transmission Control of Double Partition Windows Using T-Shaped Acoustic Resonators</a></li>
<li><a href="#p144">Development and Application of High Damping Alloys for Noise and Vibration Control</a></li>
<li><a href="#p406">Internal Resistance Optimization of a Helmholtz Resonator in Noise Control of Small Enclosures</a></li>
<li><a href="#p755">Design of Sydney Olympic Stadium for Mitigation of Crowd-Induced Vibration</a></li>
<li><a href="#p244">Theoretical and Experimental Investigation on Power Flow of a Raft Vibration Isolation System</a></li>
<li><a href="#p241">Transmission Path Characterization for Passive Vibration Control</a></li>
<li><a href="#p23">Particle Damping for Vibration and Noise Reduction</a></li>
</ul>
<li>S-Pattern recognition in acoustics and vibration</li>
<ul>
<li><a href="#p454">Reassignment Vector Field for Time-Frequency Segmentation</a></li>
<li><a href="#p491">Novel Transform for Vibro-Acoustical Recognition of Bilinear Systems</a></li>
<li><a href="#p541">Separating Gear and Bearing Signals for Bearing Fault Detection</a></li>
</ul>
<li>S-Shunt damping technology for control of sound and vibration</li>
<ul>
<li><a href="#p722">Sound Absorption of a Vibrating Plate with Piezoelectric Materials and Passive Electrical Networks</a></li>
<li><a href="#p326">Vibration Suppression Performances of Power Harvesting Systems Using Piezoelectric Transducers</a></li>
<li><a href="#p528">Some Results on Control of Sound Radiation Using Shunt Piezoelectric Materials</a></li>
</ul>
<li>S-Sound insulation</li>
<ul>
<li><a href="#p456">Comparative Analysis of Retrofit Windows for Noise Control at a Hotel</a></li>
<li><a href="#p687">Lightweight Timber Floors: a Simple Guide to Low-Frequency Impact Insulation</a></li>
<li><a href="#p346">Design Chart of Sound Insulation for Multiple Panels</a></li>
<li><a href="#p597">Studies on Insertion Loss Experiment of Cracked Plates</a></li>
<li><a href="#p367">Subjective Evaluation of Heavy-Weight Impact Sounds Generated by an Impact Ball</a></li>
<li><a href="#p364">Reducing the Heavyweight Impact Sound Levels in Reinforced Concrete Structures Using Viscoelastic Damping Materials</a></li>
<li><a href="#p476">Investigation of a Two-Parameter System of Evaluating Impact Noise Insulation</a></li>
<li><a href="#p7">The Directivity of the Forced Radiation of Sound from Panels and Openings</a></li>
<li><a href="#p577">Comparison of Experiment, Finite Element and Wave Based Models for Mass Inclusions in Poro-Elastic Layers</a></li>
<li><a href="#p690">Correlation of Impact Isolation Test Results Using Standard Tapping Machine and Heavy/soft Impact Source</a></li>
<li><a href="#p779">A Study on the Measurement of Sound Insulation of a Small-Size Window</a></li>
<li><a href="#p575">Implementation of a Hybrid Model for Prediction of Sound Insulation of Finite-Size Multilayered Building Elements</a></li>
<li><a href="#p469">Guide for Flanking Sound Transmission in Wood Framed Construction - Airborne Sources</a></li>
<li><a href="#p574">The Road Traffic Noise Attenuation by External Wall of Office Building in Standard Work Conditions</a></li>
</ul>
<li>S-Sound quality of vehicles, appliances and motors</li>
<ul>
<li><a href="#p824">FFT Based Complex Critical Band Filter Bank and Time-Varying Loudness, Fluctuation Strength and Roughness</a></li>
</ul>
<li>S-Spatial hearing in human environments</li>
<ul>
<li><a href="#p61">Three-Dimensional Acoustic Displays in a Museum Employing WFS (Wave Field Synthesis) and HOA (High Order Ambisonics)</a></li>
<li><a href="#p158">Psychoacoustic Evaluation of a New Earpiece for Augmented-Reality Audio</a></li>
<li><a href="#p328">Acoustic Clarity and Auditory Room Size Perception</a></li>
<li><a href="#p65">Ambisonic Localisation - Part 2</a></li>
<li><a href="#p512">Binaural and Monaural Helmet Systems: Noise Considerations</a></li>
</ul>
<li>S-Transport noise and vibration</li>
<ul>
<li><a href="#p55">Driver Exposure to Noise from Audio Tactile Line Marking in Queensland</a></li>
<li><a href="#p816">But are the trains getting any quieter?</a></li>
<li><a href="#p383">Study on Calculating Acoustic Sensitivity of Car Cab Based on Finite Element Method</a></li>
<li><a href="#p162">Noise in Highways: Development of a Statistical Prediction Model</a></li>
<li><a href="#p35">Vibrations of Multi-Span Bridges Under Moving Loads</a></li>
<li><a href="#p409">Reduction of Ground Vibration by Means of Ground Improvement Along a Railway Track</a></li>
<li><a href="#p119">A Model for Calculating Vibration from a Railway Tunnel Buried in a Full-Space Including Rigid Bedrock</a></li>
<li><a href="#p602">Study on Using Noise for Adhesion Control System of Railway Vehicle</a></li>
<li><a href="#p582">Structure-Borne Sound Contribution into Earth-Moving Machine Cabs</a></li>
<li><a href="#p345">Investigation of STL Measurement Method at the Vehicle Component Level and Correlation between Measurement and Prediction</a></li>
<li><a href="#p81">On Reducing the Shock Response of a Single Degree of Freedom Vehicle Model by Switching the Damping Coefficient</a></li>
<li><a href="#p271">Experimental Verification of Full Vehicle Sea Model</a></li>
</ul>
<li>S-Underwater and ship acoustics</li>
<ul>
<li><a href="#p178">Comparison of Transmission Loss Models at Mid-Frequency against Shallow Water Data</a></li>
<li><a href="#p389">Response of Hull Plates Due to Turbulent Boundary Layers</a></li>
<li><a href="#p305">The Study on the Effect of the Lateral Vibration of Shafting on Underwater Structural Acoustic Radiation</a></li>
<li><a href="#p341">Assessing the Impact of Underwater Noise on Marine Fauna: A Software Tool</a></li>
<li><a href="#p489">Advances in Monitoring and Mitigation of Ship Signatures</a></li>
<li><a href="#p269">Application of Rational Orthogonal Wavelets to Active Sonar Detection of High Velocity Targets</a></li>
<li><a href="#p698">Approaches for Automating Underwater Simulations by PE Method</a></li>
<li><a href="#p668">Measurement of the Underwater Ship Noise by Means of the Sound Intensity Method</a></li>
<li><a href="#p562">Gauging of Hydroacoustic Transducers in Small-Scale Measurement Pools Using Continuous Signals</a></li>
<li><a href="#p21">Underwater Acoustic Propagation Model to Simulate Seismic Oceanography Experiments</a></li>
<li><a href="#p72">Sonobuoy Display Integration</a></li>
<li><a href="#p717">Improved Structure-Acoustic Interaction Models, Part I: Model Development</a></li>
<li><a href="#p297">Ocean Acoustic Interferometry Experiment</a></li>
<li><a href="#p622">Acoustic Signature of a Submarine Hull</a></li>
<li><a href="#p718">Improved Structure-Acoustic Interaction Models, Part II: Model Evaluation</a></li>
<li><a href="#p689">Optimum Quasi-Adaptive Resonance Changer for Submerged Vessel Signature Reduction</a></li>
<li><a href="#p22">Underwater Noise Impact of Offshore Wind Farms During Construction and Operation Phases</a></li>
<li><a href="#p619">A Boundary Element Package Containing Approximate Solvers for Treating High Frequency Acoustic Scattering</a></li>
<li><a href="#p730">Spectral Characteristics of Wall Pressure Fluctuations for Surface Ships</a></li>
<li><a href="#p615">Excitation of a Submarine Hull by Propeller Forces</a></li>
<li><a href="#p681">Recent Developments in Fibre Optic Hydrophone Technology</a></li>
<li><a href="#p221">Diver Detection Sonars and Target Strength: Review and Discussions</a></li>
<li><a href="#p159">Some Study of Dynamic and Acoustic Character of Steerable Streamers for Ocean Exploration</a></li>
</ul>
<li>S-Uses of acoustic energy density in active control</li>
<li>S-Vibration response of buildings and structures to wind and fluid flow</li>
<li>S-Vibroacoustics and shock excitation of spaceflight vehicles</li>
<ul>
<li><a href="#p707">Radiation Efficiency of Acoustic-Excited Plates with Stringer Attachments</a></li>
<li><a href="#p753">Attenuation of Shock Transmission Through a Launch Vehicle Payload Adaptor</a></li>
<li><a href="#p177">Initial Assessment of the Ares I-X Launch Vehicle Upper Stage to Vibroacoustic Flight Environments</a></li>
<li><a href="#p123">Vibroacoustic Response of the NASA ACTS Spacecraft Antenna to Launch Acoustic Excitation</a></li>
<li><a href="#p539">MSL Pyroshock Development Test Program for Shock Mitigation</a></li>
<li><a href="#p614">Virtual Vibration Test and Verification for the Satellite</a></li>
<li><a href="#p393">Study on Numerical Vibro-Acoustic Analysis of Spacecrafts</a></li>
<li><a href="#p533">Development of a General Periodic SEA Subsystem for Modeling the Vibro-Acoustic Response of Complex Structures</a></li>
</ul>
<li>S-Vibroacoustics of building structures</li>
<ul>
<li><a href="#p818">Simulation of Mechanical Systems in Loading with Broadband Random Axitation</a></li>
<li><a href="#p147">The Dynamic Analysis of a Building Structure - Acoustic Volume Interaction System Excited by Human Footfall Impacts</a></li>
<li><a href="#p368">Measurements of Viscoelastic Properties of Concrete Structure Using Beam Transfer Function Method</a></li>
<li><a href="#p551">Vibration Control of Buildings: Case Studies</a></li>
<li><a href="#p488">Two Modelling Approaches for Periodic Rib-Stiffend Plates Typcial of Floor Assemblies</a></li>
<li><a href="#p337">Control of Radiated Noise from Ship’s Cabin Floor</a></li>
</ul>
</ul>
</ul>
<hr>
<h4 style="text-align: center;">All rights reserved. Permission is granted for any person to reproduce a part of any abstract provided that the permission is obtained from the author(s) and credit is given to the author(s) and these conference proceedings.</h4>
<hr>
<h2><a name="p542" class="affilation"></a>Acoustic Detection of Tension Wood in Eucalypts</h2>
<h3>Jun Li Yang, Voichita Bucur, Dung Ngo</h3>
<p class="affilation">Ensis, Private Bag 10, Clayton South, Victoria 3169, Australia</p>
<p><b>ABSTRACT</b><br>
The occurrence and distribution of tension wood in trees can result in major defects in manufactured wood products. The nondestructive detection and location of tension wood in trees and logs is a major interest for hardwood industry in Australia. This paper proposes a combined acoustic method using ultrasonic waves and stress waves for 2D imaging of the presence of tension wood in transversal section of logs. Five discs of 10 cm thickness cut from <i>Eucalyptus delegatensis</i> logs from regrowth forests and one disc from an <i>E. nitens</i> log from Hancock Victorian Plantations were selected. As wood material has an orthotropic structure, velocities were measured on the three primary symmetry axes. It was demonstrated that on the transverse section of discs, the presence and the location of tension wood may be determined. In the same time, the opposite wood, the lateral wood and the juvenile wood zones may also be detected. These methods show potential for use in sawmills for the inspection of defective features in cross sections of logs and also in standings trees of commercial forests, parks and public gardens.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p542.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p699" class="affilation"></a>The Safeguarding of Marine Mammals Development of Detection Methods in a Blast Environment</h2>
<h3>Vincent Capizzi, Thomas Boxoen, Mark Blake, Anne Shen</h3>
<p class="affilation">Heggies Pty Ltd, Level 2, 2 Lincoln Street Lane Cove NSW 2066 Australia</p>
<p><b>ABSTRACT</b><br>
This paper describes the selection of a preferred method for the detection of marine mammals in the vicinity of a construction site where underwater blasting will be taking place. This is in response to the need to minimize underwater noise and shock on these animals. The impact on marine mammals from underwater blasting varies but depends primarily on the size of the blast, the proximity of the animal to the explosion site and the size of the mammal. The advantages and disadvantages of underwater acoustics and alternative monitoring techniques such as infra-red imaging and visual sighting from aircraft or unmanned airborne vehicles (UAVs) are investigated. A Systems Engineering approach is used to select a preferred configuration of acoustic arrays and UAVs.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p699.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p278" class="affilation"></a>An Asymptotic Approach for the Coupled Dispersion Characteristics of a Fluid-Filled Cylindrical Shell</h2>
<h3>Abhijit Sarkar, Venkata R. Sonti</h3>
<p class="affilation">Facility for Research in Technical Acoustics, Department of Mech. Engg., Indian Institute of Science, Bangalore - 560012, India</p>
<p><b>ABSTRACT</b><br>
The coupled wavenumbers in the axisymmetric mode of a fluid-filled cylindrical shell are studied. The coupled dispersion equation of the system is rewritten in the form of the uncoupled dispersion equation of the structure and the acoustic domain, with an added fluid-loading term () due to the coupling. Using the smallness of poisson’s ratio, a double-asymptotic solution to this equation is found for large and small values of . Analytical expressions are derived for the coupled wavenumbers. Different asymptotic expansions are used for different frequency ranges with continuous transitions occurring between them. The wavenumber solutions are continuously tracked as varies from small to large values. A general trend observed is that a given wavenumber branch transits from a rigid-walled solution to a pressure-release solution with increasing . Also, it is found that at any frequency where two wavenumbers intersect in the uncoupled analysis, there is no more an intersection in the coupled case, but a gap is created at that frequency. Only the axisymmetric mode is considered, however the findings can be extended to the higher order modes.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p278.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p295" class="affilation"></a>Stochastic Finite Element Analysis of the Free Vibration of Functionally Graded Material Plates</h2>
<h3>Afeefa Shaker (1), Wael Abdelrahman (2), Mohammad Tawfik (3), Edward Sadek (1)</h3>
<p class="affilation">(1) Department of Aerospace Engineering, Cairo University, Cairo, Egypt (2) Department of Aerospace Engineering, King Fahd University of Petroleum and Minerals, Dhahran, 31261, Saudi Arabia (3) Modeling and Simulation in Mechanics Department, German University in Cairo, New Cairo City, Cairo, Egypt</p>
<p><b>ABSTRACT</b><br>
The superior properties of Functionally Graded Materials (FGM) are usually accompanied by randomness in their properties due to difficulties in tailoring the gradients during manufacturing processes. Using the Stochastic Finite Element Method (SFEM) proved to be a powerful tool in studying the sensitivity of the static response of FGM plates to uncertainties in their material properties. This tool is yet to be used in studying free vibration of FGM plates. The aim of this work is to use a Second Order Reliability Method (SORM), combined with a nine-noded isoparametric Lagrangian element based on the third order shear deformation theory to investigate sensitivity of the fundamental frequency of FGM plates to material uncertainties. These include uncertainties in ceramic and metal Young’s modulus and Poisson’s ratio, their densities and the ceramic volume fraction. The developed code utilizes MATLAB capabilities to derive the derivatives of the stiffness and mass matrices symbolically with a considerable reduction in calculation time. Calculating the eigenvectors at the mean values of the variables and updating them only at the last iteration significantly increases solution speed. The results of the stochastic finite element code are compared to published results and to the results of the well-established Monte Carlo simulation technique with importance sampling. Results show that the relative importance of variations in the constituents’ properties is highly dependent on the volume fraction and is virtually independent of the frequency ratio for practical values of solution reliability. SORM is proven to be an excellent rapid tool in the stochastic analysis of free vibration of FGM plates, when compared to the slower Monte Carlo simulation techniques.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p295.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p751" class="affilation"></a>Acoustically Controlled Rotations of a Disk in Free Field</h2>
<h3>Arturo O. Santillán (1), Karen Volke-Sepúlveda (2), Ricardo R. Boullosa (1)</h3>
<p class="affilation">(1) Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México, Circuito Exterior s/n, Cd. Universitaria, A. P. 70-186, 02510 México D. F., México (2) Instituto de Física, Universidad Nacional Autónoma de México, A. P. 20-364, 01000 México D. F., México</p>
<p><b>ABSTRACT</b><br>
In general, forces are caused on objects when sound waves interact with their surfaces. Based on this phenomenon, acoustical levitation is a technique in which stationary sound fields are used to trap small samples, liquid or solid, compensating the action of gravity. Rotations of suspended objects in acoustic levitation devices are common, which are due mainly to asymmetries of the samples and sometimes to instabilities of the system. This fact turns out to be disadvantageous for applications where a precise control of the sample position is desired. The general objective of this work has been to study the extent to which it is possible to transfer angular momentum from a sound field to matter, and to control the rotations of an object. An original contribution of the work is that the acoustic fields have been produced in free space, i.e., without the need of a cavity, which gives the advantage of free access to the sample. We present an analysis of the properties of acoustic fields analogous to optical vortices; by using these kinds of sound fields, we show experimentally the generation of rotations in a solid disk produced by acoustic waves. In addition, by generating acoustic vortices of the first and second orders, we demonstrate that the direction of rotation is consistent with the corresponding helicity; we also analyse the differences of the angular momentum transfer between both cases. On this basis, we conclude that this mechanism can be used to achieve rotational control of acoustically levitated objects.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p751.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p494" class="affilation"></a>Dependence of Oscillational Instabilities on the Amplitude of the Acoustic Wave in Single-Axis Levitators</h2>
<h3>Arturo O. Santillán (1), Ricardo R. Boullosa (1), Vicente Cutanda-Henríquez (2), Antonio Pérez López (1)</h3>
<p class="affilation">(1) Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México, Circuito Exterior s/n, Cd. Universitaria, A. P. 70-186, 02510, Mexico (2) Institute of Sensors, Signals and Electrotechnics, Faculty of Engineering, University of Southern Denmark, Niels Bohrs Allé 1, 5230 Odense M, Denmark</p>
<p><b>ABSTRACT</b><br>
It is well known that acoustic waves exert forces on a boundary with which they interact; these forces can be so intense that they can compensate for the weight of small objects up to a few grams. In this way, it is possible to maintain solid or liquid samples levitating in a fluid, avoiding the use of containers, which may be undesirable for certain applications. Moreover, small samples can be manipulated by means of acoustic waves. In this paper, we report a study on the oscillational instabilities that can appear on a levitated solid sphere in single-axis acoustic devices. A theory published on the topic predicts that these instabilities appear when the levitator is driven with a frequency above the resonant frequency of the empty device. The theory also shows that the instabilities can either saturate to a state with constant amplitude, or they can grow without limit until the object falls out of the levitating field or strikes a boundary of the device. These theoretical results are consistent with experiments. According to the theory, the instabilities due to oscillations are produced by a phase difference between the position of the levitated object and the variations of the sound pressure amplitude in the cavity because of the presence of the sample. The theory predicts that the phase difference depends on the speed of the oscillating object. In this paper, we give for the first time experimental evidence that shows the existence of the phase difference, and that it is negatively proportional to the oscillation frequency of the levitated sample. We also present experimental results that show that the oscillational instabilities can be reduced if the amplitude of the acoustic wave is increased; as a result, stable conditions can be obtained where the oscillations of the sphere are highly damped. This dependence of the instabilities on the amplitude of the driving acoustic wave, however, cannot be described with the existing theory.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p494.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p90" class="affilation"></a>Zero-Pole Analysis of a Tensioned String with Periodic Stiffeners</h2>
<h3>Benjamin A. Cray (1), Andrew J. Hull (1), Albert H. Nuttall (2)</h3>
<p class="affilation">(1) Autonomous Systems and Technology Department (2) Sensor and Sonar Systems Department, Naval Undersea Warfare Centre Division, Newport, RI 02841, USA</p>
<p><b>ABSTRACT</b><br>
This paper analyzes the zero-pole locations of an infinite length, tensioned string that has attached periodic stiffeners. The dynamic response of the system is derived for distributed wavenumber forcing and discrete point forcing acting on the string. These wavenumber-frequency transfer functions are then written in zero-pole format by a mathematical transformation of their infinite series. Once this is accomplished, the location of the system poles and zeros becomes apparent and they can be plotted in the wavenumber-frequency plane. It is shown that there are specific regions where an infinite number of poles can exist and specific regions where poles cannot exist. For the system with wavenumber forcing, the system zeros correspond very closely to the system poles except in the area of the fundamental string resonance. For the system with point forcing, the zeros can exist in the entire wavenumber-frequency plane except at the fundamental resonance.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p90.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p399" class="affilation"></a>Modal Probabilistic Analysis: Theory and Application</h2>
<h3>Christophe Heinkelè, Stèphane Pernot, Franck Sgard, Claude-henri Lamarque</h3>
<p class="affilation">Department of Civil Engineering - URA CNRS 1652, Ecole Nationale des Travaux Publics de l’Etat, Rue Maurice Audin, 69518 Vaulx-en-Velin Cedex, France</p>
<p><b>ABSTRACT</b><br>
The randomness of the parameters such as Young’s modulus or the loss factor of a mechanical system can have considerable influence upon its response. The present study aims at providing an analytical method to evaluate the impact of this randomness. We focus on the frequency response of a discrete vibrating system with separated modes and random damping. The probabilistic method is based on normal modes with the Finite Element Method. This new method will be called the modal probabilistic analysis. This theory leads to the definition of an envelope of the response. Then these envelopes are used to characterize the law of probability that is governing the damping : this identification method is illustrated using a vibrating system composed of an Euler-Bernoulli beam.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p399.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p82" class="affilation"></a>The Use of the Propagation Equation for the Case of Plane Longitudinal Waves Through Bars with Variable Section, to Study the Impedance Transformers Utilized for Ultrasonic Welding</h2>
<h3>Grigore Liviu Odobescu, Rareş Alexandru Odobescu</h3>
<p class="affilation">Institute of Solid mechanics, Rumanian Academy</p>
<p><b>ABSTRACT</b><br>
The ultrasonic vibrations, in the range (20-40) kHz, having high energy (1-2 kW) are utilized for non-conventional welding. In this manner metal combination like aluminium - aluminium can be welded. This paper proceeds from the general form of the propagation equation of plane longitudinal waves through bars with different sections and thickness. The mathematical expressions are found for the variations in form of the mechanical tensions and for the amplitude of vibration as a function of the shape of the bars, and the material from which they are made. The curves which can be traced help to design the impedance transformers, the component which is placed between the ultrasound vibration generators (formed by piezoelectric elements) and the welding head. The derived equations are verified for the case of a welding machine of type TELSONIC-MPS-2. The paper proposes the realization of a program in order to calculate and then experimentally verify the case of an acoustic chain intended to be substituted for the defect acoustic chain, which exists on a welding machine of type TELSONIC-MPS-2. The paper presents the principle for the calculus, the calculus mode and experimental results obtained, for comparison with a few models selected for this purpose.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p82.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p229" class="affilation"></a>Vibration Analysis of a Cracked Beam Subjected to a Traveling Vehicle</h2>
<h3>Hai-Ping Lin</h3>
<p class="affilation">Department of Mechanical and Automation Engineering, Dayeh University, 112 Shanjiao Rd., Dacun, Changhua, Taiwan 51591, R.O.C.</p>
<p><b>ABSTRACT</b><br>
An analytical method is developed to present the forced responses of a cracked simply-supported beam subjected to a traveling vehicle. The cracked beam system is modeled as a two-span beam and each span of the continuous beam is assumed to obey the Euler-Bernoulli beam theory. The crack is modeled as a rotational spring with sectional flexibility and a traveling vehicle is modeled as two concentrated moving loads separated by the distance of the vehicle wheelbase. Using the analytical transfer matrix method by considering the compatibility requirements on the crack, eigensolutions of this cracked system can be obtained explicitly. The forced responses can then be determined by modal expansion theory.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p229.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p496" class="affilation"></a>Estimation of the Active and Reactive Sound Power Using Hyper-Matrices of Impedance</h2>
<h3>Jorge P. Arenas, Cristóbal Albarracín</h3>
<p class="affilation">Institute of Acoustics, Universidad Austral of Chile, Valdivia, P. O. Box 567, Chile</p>
<p><b>ABSTRACT</b><br>
A numerical approach to estimate the active and reactive sound power radiated by a baffled plane piston is presented. The active part of the sound power is related to the generation of sound and the reactive part is associated with the reaction of the medium. Usually the sound power is estimated by a direct integration of the Rayleigh integral. However, this technique is time-consuming because of the numerical integration of the sound field. Here the vibrating surface is replaced by a number of small equivalent pistons, and the sound power is estimated by means of the radiation impedance matrix of the structure. Since the impedance matrix depends on the two-dimensional geometry and frequency, the matrix can be handled as an hyper-matrix which reduces significantly the computation time. This approach is applied to various piston shapes and the results are compared with traditional methods.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p496.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p436" class="affilation"></a>Vibration Control Method of Speaker Enclosure and its Effect on Replay Sound Quality and Summing Localization</h2>
<h3>Kiminobu Nishimura (1), Ryuhkei Ina (2)</h3>
<p class="affilation">(1) Department of Mechanical Engineering, School of Engineering, Kinki University, Higashi-Hiroshima, Hiroshima, 739-2116, Japan (2) Kryna & Pluton Inc., 1156-1 Kanamori, Machida, Tokyo, 201, Japan</p>
<p><b>ABSTRACT</b><br>
Vibrations occurred in stereophonic equipment seems not a minor cause for harmonic distortion. In the previous report, we proposed a new method to suppress higher harmonics contained in vibration and electric and/or acoustic signals by eliminating unnecessary vibration on stereophonic equipments. Its effect on sound quality and summing localization was remarkable one. In this report, for further improvement, we propose a new method to eliminate directly the vibration on a baffle to vibration absorbing board set behind the enclosure through a transmission system. The effects on suppression of vibrations on the speaker baffle were measured as the changes in higher order harmonics of not only vibration but also radiated sound under sinusoidal input. Then, the suppression of the harmonics distortion on the baffle realizes following improvement of sound quality related with noise reduction, increase of clearness, distinct sound, increase of voluminosity at lower frequency, decrease of overlap of before and after notes, and etc. Furthermore, three dimensional representation ability of replay sound was also improved to illustrate well the location of instruments on a stage.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p436.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p365" class="affilation"></a>Parametric Vibrations of the Rotor</h2>
<h3>Livija Cveticanin</h3>
<p class="affilation">Faculty of Technical Sciences, University of Novi Sad, Novi Sad, 21000, Serbia</p>
<p><b>ABSTRACT</b><br>
In this paper the parametrically excited vibrations of the rotor are analyzed. The rotor is considered as a shaft-disc system. The parameters of the system are time dependent. The mathematical model of the rotor is a system of two coupled differential equations of Hill’s type. The parametric excitation has the form of the Jacobi elliptic function. The vibrations of the system are obtained analytically and numerically. Two analytical methods for solving are developed: the method of harmonic balance based on the elliptic functions and the Krylov-Bogolubor method with variable amplitude and phase. The analytical solutions are compared with numerical ones. They are in a good agreement.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p365.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p44" class="affilation"></a>Gyroscopic Effects in Vibrating Fluid-Filled Spheres Subjected to Inertial Rotation</h2>
<h3>M. Shatalov (1,2), S. V. Joubert (2), C. E. Coetzee (2), I. Fedotov (2)</h3>
<p class="affilation">(1) Sensor Science and Technology (SST) of CSIR Material Science and Manufacturing (MSM), P.O. Box 395, Pretoria 0001, South Africa (2) Department of Mathematics and Statistics, Tshwane University of Technology, P.O. Box X680, Pretoria 0001, South Africa</p>
<p><b>ABSTRACT</b><br>
In symmetric distributed structures subjected to vibration and an inertial rotation, the vibrating patterns turn in the direction of revolution at a rate proportional to the inertial angular rate. This effect has numerous applications in navigational instruments, such as hemispherical rotational sensor. It is also important for astrophysics and seismology to understand the dynamics of pulsating stars and earthquake series. The coefficient of proportionality between the inertial and vibrating pattern rates depends on the geometry of structure, mode number, et cetera, and plays a crucial role in this study. In this paper we consider gyroscopic effects in hollow solid spheres filled with an inviscid fluid. The dynamics of the sphere are considered in terms of linear elasticity. Two limiting cases of the fluid motion are considered: in the first case, we suppose that the fluid is fully involved in the rotation; in the second, the fluid does not rotate relative to the inertial reference frame. It is also assumed that the angular rate is constant and much smaller than the lowest eigenvalue of the system. Hence centrifugal effects, proportional to the square of the angular rate, are considered to be negligible. The effects of structure prestress due to gravitational forces are also neglected. Two types of nonaxisymmetric modes of the system are considered, namely spheroidal and torsional. A numerical experimental observation is made that, for lower eigenvalues and lower circumferential wave numbers, the difference between the modulus of the rotational angular rates of the fluid-filled sphere and those of its vibrating patterns is small. However, this difference is large for higher modes and eigenvalues of the system.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p44.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p48" class="affilation"></a>Investigation of Gyroscopic Effects in Vibrating Fluid-Filled Cylinders Subjected to Axial Rotation</h2>
<h3>M. Shatalov (1,2), S. V. Joubert (2), E. Voges (2)</h3>
<p class="affilation">(1) Sensor Science and Technology (SST) of CSIR Material Science and Manufacturing (MSM), P.O. Box 395, Pretoria 0001, South Africa (2) Department of Mathematics and Statistics, P.B.X680, Pretoria 0001 FIN-40014 Tshwane University of Technology, South Africa</p>
<p><b>ABSTRACT</b><br>
Vibrating patterns of distributed oscillating structures, subjected to rotation, also turn in the direction of inertial revolution but with different angular rates, which depend on the geometry of the structures, the number of modes, etc. This effect, found by G. Bryan in 1890, has numerous applications in navigational instruments such as cylindrical rotational sensors. This effect is also important in astrophysics and seismology. In the present paper we consider the main principles of the theory of gyroscopic effects in distributed structures. The model of a thick vibrating cylinder filled with a fluid and subjected to inertial rotation is analyzed. The dynamics of the cylinder is considered in terms of linear elasticity and the fluid is supposed to be ideal and inviscid, but fully involved in the rotation. It is presumed that the angular rate of inertial rotation is constant and has axial orientation. It is also assumed that the angular rate is much smaller than the lowest eigenvalue of the system and hence the centrifugal effects, proportional to square of the angular rate, are neglected. The influence of the following on Bryan’s factor are investigated: the non-axisymmetric modes of the system, the eigenvalues for a fixed mode, the mass density of the fluid, the modulus of elasticity, the bulk modulus, Poisson ratio, the thickness and inner radius of the cylinder. It is shown that the difference between rotational angular rates of the system and its vibrating patterns is substantial for lower eigenvalues and circumferential wave numbers.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p48.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p49" class="affilation"></a>On Gyroscopic Effects in Vibrating and Axially Rotating Solid and Annular Discs</h2>
<h3>M. Shatalov (1,2), S. V. Joubert (2), I. Fedotov (2), W. Pretorius (2)</h3>
<p class="affilation">(1) Sensor Science and Technology (SST) of CSIR Material Science and Manufacturing (MSM), P.O. Box 395, Pretoria 0001, South Africa (2) Department of Mathematics and Statistics, Tshwane University of Technology, P.B.X680, Pretoria 0001, South Africa</p>
<p><b>ABSTRACT</b><br>
“Bryan’s effect” - that is, the effect of a vibrating pattern’s precession in the direction of inertial rotation of a vibrating ring - was discovered by G. Bryan in 1890. This effect has several applications in navigational instruments, such as cylindrical, hemispherical and planar circular disc rotational sensors. The model of a thin circular disc vibrating in its plane and subjected to inertial rotation is considered. The dynamics of the disc gyroscope are considered in terms of linear elasticity. Two models are considered: solid discs and a composite disc consisting of concentric annular discs with various boundary conditions on the inner and outer circumferences. It is assumed that the angular rate of inertial rotation of the composite disc is constant and has axial orientation. It is also assumed that this angular rate is much smaller than the lowest eigenvalue of the composite disk. Hence any centrifugal effects and quantities that are proportional to the square of the angular rate are negligible. Our model is formulated in general terms and then compared to a formulation in terms of Novozhilov-Arnold-Warbur-ton’s theory of thin shells. The system of equations of motion of the disc is separated and transformed into a pair of wave equations in polar coordinates. A solution is obtained in terms of Bessel and Neumann functions. Various non-axisymmetric modes of the composite disc are considered and the dependence of Bryan’s effect on eigenvalues, mass densities of the composite disc, its modulii of elasticity, Poisson ratios, outer and inner radii of the disc, and for various types of boundary conditions, are investigated.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p49.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p626" class="affilation"></a>Statistical Energy Analysis Using Transmission Coefficients Derived for Finite Coupled Plates</h2>
<h3>Michael Skeen, Nicole Kessissoglou</h3>
<p class="affilation">School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney, NSW 2052, Australia</p>
<p><b>ABSTRACT</b><br>
Prediction of vibration transmission in built up structures such as buildings or ship hulls is an important consideration in modern engineering design. As the excitation frequencies increase and hence the number of modes increase, it is more practical to consider average vibrational responses and their distribution over the structure using energy techniques such as Statistical Energy Analysis (SEA). The successful use of SEA strongly depends on the accurate estimation of the SEA parameters, namely the coupling loss factors (CLFs). This paper investigates the dynamic response of coupled plates using an SEA model with CLFs obtained from transmission coefficients derived for finite coupled plate structures. Traditionally, the CLFs in an SEA model have been obtained from transmission coefficients derived for infinite and semi-infinite structures, due to the ease with which they can be derived. Conversely, transmission coefficients for finite structures are difficult to obtain due to the reverberant field. In this paper, transmission coefficients for finite coupled structures are derived using an analytical waveguide method which is used to determine the wave amplitudes on each side of a junction. A scattering matrix is then used to separate the reverberant waves leaving the junction into reflected and transmitted components. The energy flow due to each of these waves is obtained using a wave impedance method, which is subsequently used to determine the transmission coefficients. CLFs are obtained from the transmission coefficients for a finite L-shaped plate under multiple point force excitation. The SEA subsystem energy levels using these CLFs are compared to results obtained from traditional SEA theory as well as frequency and spatially averaged energy levels obtained from the analytical waveguide method. Results for both the CLFs and SEA energy levels for semi-infinite and finite structures are in very good agreement with each other and with the exact average energy levels obtained from the analytical model.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p626.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p688" class="affilation"></a>Study on the Characteristics of Vibration and Acoustic Radiation of Damaged Stiffened Panels</h2>
<h3>Ming Hong (1), Xin-yi Guo (2), Lian-hai Liu (3), Gen-tian Li (4)</h3>
<p class="affilation">(1) Department of Naval Architecture, Dalian University of Technology, Dalian 116024, China (2) Acoustic Research Institute, Chinese Academy of Science, Beijing 100080, China (3) American Bureau of Shipping Ship Classification, Pacific Division Shanghai 200003, China (4) China Ship Development & Design Center, Shanghai 201102, China</p>
<p><b>ABSTRACT</b><br>
The characteristics of dynamic and acoustic radiation of a damaged stiffened panel are investigated by using FEM/BEM. The modes of damages are introduced into the finite element analysis. Isotropic damage modes are modeled by globally and isotropically softening the stiffness. Based on Mindlin theory, a shell element model is built to model the healthy and damaged structures and to calculate the dynamic characteristics and response of a structure surface. With the linear boundary element, the sound pressure of structure radiating outwards can be calculated and the radiated power and directivity can then be obtained. The influences of various locations and extents of damages on vibration and acoustic characteristics are studied. An analysis method has been established to analyze acoustic behavior of a damaged structure. Conclusions have been drawn from the analyses of some typical examples. The proposed method is useful for assessing the influences of the damages present in a stiffened panel on its acoustic radiation properties.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p688.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p500" class="affilation"></a>Sound Source Localization with Bio-Mimicking Parasitoid Fly</h2>
<h3>Na Ta, Zhushi Rao, Qingsheng Wang</h3>
<p class="affilation">State key laboratory of Mechanical system and vibration, Shanghai Jiaotong University, Shanghai, 800 Dongchuan Road, China</p>
<p><b>ABSTRACT</b><br>
Parasitoid fly (Diptera: Tachinidae: Orminii) demonstrate a remarkable ability to detect the direction of an incident sound stimulus by means of its uniquely structured acoustic sensory organs. In this paper, based on the auditory mechanism of the fly, a nonlinear model that can determine the incident direction of the sound is established. The analytical results are testified by experiments. Directional hearing mechanism of the model as well as effects of mechanical parameters is discussed.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p500.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p706" class="affilation"></a>Wave Propagation, Reflection and Transmission in Curved Beams</h2>
<h3>Seung-Kyu Lee (1), Brian Mace (2), Michael Brennan (2)</h3>
<p class="affilation">(1) NVH Team, R&D Centre, Hankook Tire Co., Ltd., 3-1, Jang-Dong, Yuseong-Gu, Daejon, 305-725, Korea (2) Institute of Sound and Vibration Research, University of Southampton, Highfield, Southampton, SO17 1BJ, UK</p>
<p><b>ABSTRACT</b><br>
Wave motion in thin, uniform, curved beams with constant curvature is considered. The beams are assumed to undergo only in-plane motion, which is described by the sixth-order coupled differential equations based on Flügge’s theory. In the wave domain the motion is associated with the three independent wave modes. A systematic wave approach based on reflection, transmission and propagation of waves is presented for the analysis of structures containing curved beam elements. Displacement, internal force and propagation matrices are derived. These enable transformations to be made between the physical and wave domains and provide the foundation for systematic application of the wave approach to the analysis of waveguide structures with curved beam elements. The energy flow associated with waves in the curved beam is also discussed. It is seen that energy can be transported independently by the propagating waves and also by the interaction of a pair of positive and negative going wave components which are non-propagating, i.e. their wavenumbers are imaginary or complex. A further transformation can be made to power waves, which can transport energy independently.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p706.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p763" class="affilation"></a>Free Vibration Analysis of Sandwich Hemispherical Shells with Constrained Electro-Rheological Fluid Damping</h2>
<h3>Sharnappa, N. Ganesan, Raju Sethuraman</h3>
<p class="affilation">Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600036, India</p>
<p><b>ABSTRACT</b><br>
This paper deals with the dynamic characteristics of hemispherical sandwich shells with electro-rheological (ER) fluid core under clamped free and clamped clamped conditions. The free vibration and damping analysis is carried out by using the semi-analytical finite element method. Three noded line elements with seven degree of freedom per node are used in meridional direction and Fourier series is assumed in circumferential direction. There are two types of electro-rheological fluid cores used in the present study. The damping variation of hemispherical sandwich shell for different radius to thickness (R/t) ratio and core to facing thickness ratio (tc/tf) are carried out. The variation of damping properties of ER fluid with electric field is also investigated.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p763.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p822" class="affilation"></a>Two Observations on the Wave Approach to SEA</h2>
<h3>Svante Finnveden</h3>
<p class="affilation">MWL, Department of Aeronautical and Vehicle Engineering, KTH
SE-100 44 Stockholm
Sweden</p>
<p><b>ABSTRACT</b><br>
First, it is shown that the use of SEA coupling factors derived for the coupling of semi infinite systems is consistent with coupling power proportionality. This demonstration is axiomatic, relying on a set of postulates. It is useful in teaching SEA, as it illustrates concepts and assumptions commonly made. It might be useful for research aiming for a better set of postulates upon which a statistical energy method can be built. Second, the wave motion in double walls is investigated. A new SEA formulation is presented in which each element describe one kind of coupled cavity-wall wave motion. This formulation obsoletes the nonresonant transmission paths and compared to classical formulations, it improves results at frequencies around and a bit above the double wall resonance.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p822.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p734" class="affilation"></a>Analysis of 1/2-Order Subharmonic Resonance in a Horizontally Supported Jeffcott Rotor</h2>
<h3>Takuma Kahimura (1), Hiroshi Yabuno (1), Tsuyoshi Inoue (2), Yukio Ishida (2)</h3>
<p class="affilation">(1) Graduate School of Systems and Information Engineering, University of Tsukuba, Tsukuba 300-8573 Japan (2) Graduate School of Engineering, Nagoya University, Nagoya 464-8603 Japan</p>
<p><b>ABSTRACT</b><br>
The 1/2-order subharmonic resonance occurs when the rotational speed is in the vicinity of twice the natural frequency. The Jeffcott rotor used basically and widely in the analysis of resonancies, is a two-degree-of-freedom model with a disk at the midspan of a massless-shaft. For the above condition on the rotational speed, we clarify the nonlinear characteristics of the resonance in a horizontally supported Jeffcott rotor. Applying the method of multiple scales, we directly derive the amplitude equations for the horizontal direction and vertical direction and depict the relationship between the rotational speed and the response amplitude. Furthermore, experiments are performed and the results are compared with the theoretical ones.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p734.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p315" class="affilation"></a>The Result Analysis of the Sound Intensity Level Generated by a High Power Transformer</h2>
<h3>Tomasz Boczar, Marcin Lorenc, Dariusz Zmarzły</h3>
<p class="affilation">Opole University of Technology, Faculty of Electrical Engineering Automatic Control and Computer, Science, Opole, Mikołajczyka 5, 45-271, Poland</p>
<p><b>ABSTRACT</b><br>
The paper presents the measurement results of the noise level of a power transformer. The noise sources occurring in the transformer are presented, and the method applied and the measuring tools used are characterized. The measurements were taken in 29 points located around the transformer. The evaluation of noise was carried out based on the revised coefficient of the acoustic pressure level. The research work results presented enable the evaluation of the influence of the noise of the unit under study on its environment and make it easier to diagnose the degrees of wear of the fans installed in transformer coolers.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p315.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p657" class="affilation"></a>Vibration Based Modelling of Three Point Bend Specimen for Evaluation of Dynamic Stress Intensity Factor</h2>
<h3>V. M. Chavan (1), S. K. Maiti (2), B. K. Dutta (3)</h3>
<p class="affilation">(1) Refueling Technology Division, Bhabha Atomic Research Centre, Mumbai, 400085, India (2) Mechanical Engineering Department, Indian Institute of Technology Bombay, Mumbai, 400076, India (3) Reactor Safety Division, Bhabha Atomic Research Centre, Mumbai, 400085, India</p>
<p><b>ABSTRACT</b><br>
A vibration based modelling of impact loaded three point bend (TPB) specimen is presented for evaluation of dynamic stress intensity factor (DSIF). As a first approximation, neglecting the shear deformation and rotational inertia, the specimen has been analyzed through Euler-Bernoulli beam theory. In the present approach a multiple degree of freedom (MDOF) model has been proposed by representing the discontinuity due to crack through a mass-less rotational spring to obtain temporal motion of the specimen under impact loading. This approach offers scope for an evaluation of the DSIF and even dynamic fracture toughness through the motion related data. Sample results on the DSIF have been presented for the case of step and ramp loading. These results compare closely with results computed through two-dimensional transient finite element (FE) analysis. Possibility of an application of present method of analysis to instrumented impact tests is shown through a comparison of results with those published in the literature.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p657.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p124" class="affilation"></a>Some of the New Approaches to the Theory of Designing Acoustic Thickeners</h2>
<h3>Valentin Abakumov, Kirill Trapezon</h3>
<p class="affilation">ZTRI Department, Kyiv Polytechnic Institute, 37 Peremogi Str., Kyiv, 03056, Ukraine</p>
<p><b>ABSTRACT</b><br>
The algorithm of analytical calculation and way of planning of acoustic thickeners is considered. The types are determined by the function of the special kind containing substantial arbitrary permanent. As the ground of practical benefit of the offered algorithm, the chart of construction of acoustic thickener of energy is resulted with the detailed analysis of its main characteristics.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p124.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p748" class="affilation"></a>Dynamic Response of a Structure with Uncertainty in its Parameters and Applied Forces Using the Interval Factor Method</h2>
<h3>Wei Gao</h3>
<p class="affilation">School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney, NSW 2052, Australia</p>
<p><b>ABSTRACT</b><br>
An interval factor method is presented to describe the dynamic response of a structure with lower and upper bounds applied to its parameters (material properties, geometric dimensions) and structural excitations (applied forces). In the interval analysis method, a bounded uncertain structural parameter can be described as an interval variable in terms of its lower and upper bounds. An interval variable can further be expressed as its mean value multiplied by its interval factor. The structural stiffness and mass matrices can then be divided into the product of two parts corresponding to the interval factors and the deterministic matrix. Computational expressions for the mean value, and lower and upper bounds of the structural dynamic responses are then derived by means of mode superposition and interval operations. An example of this method is applied to a complex truss structure. The bounded uncertain structural physical parameters, geometric dimensions and applied forces of the truss structure are considered as interval variables. The effects of these uncertainties on the dynamic displacement and stress responses are examined.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p748.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p71" class="affilation"></a>Dynamic Analysis of Vehicles with Uncertain Parameters</h2>
<h3>Wei Gao, Nong Zhang</h3>
<p class="affilation">Mechatronics and Intelligent Systems, Faculty of Engineering, University of Technology, Sydney NSW 2007, Australia</p>
<p><b>ABSTRACT</b><br>
A quarter car model is used to investigate the dynamic characteristic and random vibration response of cars with uncertainty in this paper. The sprung mass, unsprung mass, suspension damping, suspension and tyre stiffness are considered as random variables. The road irregularity is considered a Gaussian random process and modeled by means of a simple exponential power spectral density. The numerical characteristics including mean value and standard deviation of the natural frequencies, mode shapes and root mean square random response of vehicles are obtained by using the Monte-Carlo simulation method. The influences of the randomness of the vehicle’s parameters on the dynamic characteristic and random response are investigated in detail using a practical example.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p71.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p228" class="affilation"></a>Dynamic Structure Modification Using Dents</h2>
<h3>Wen Nan Cheng (1), Chih Chun Cheng (1), Gary H. Koopmann (2)</h3>
<p class="affilation">(1) Deparment of Mechanical Engineering, National Chung Cheng University, Chia-Yi, 621, Taiwan, R.O.C. (2) Deparment of Mechanical and Nuclear Engineering, Pennsylvania State University, University Park, PA, USA</p>
<p><b>ABSTRACT</b><br>
In this paper, a design method to modify the vibration characteristics of a structure by creating dents, or dimples on its surface is investigated. In particular, the vibration response of a beam with several dimples is formulated using the impedance method. The dimpled beam is divided into two kinds of structural segments: one, a curved beam that is modeled as the dimple and the other, a straight beam. The frequency equation is derived by assembling the impedance of each structure segment based on conditions of force equilibrium and velocity compatibility. Then a novel method for shifting the natural frequencies of a structure to pre-assigned values by creating dimples on the structure is introduced. The dimple size and its location on the structure can be determined analytically so the time consuming process using the traditional optimal search method is thereby avoided. Several examples using this technique are demonstrated.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p228.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p448" class="affilation"></a>Some New General Results on the Fluid-Structure Interaction Problem</h2>
<h3>Yuri Bobrovnitskii</h3>
<p class="affilation">Mechanical Engineering Research Institute of Russian Academy of Sciences, Moscow 101990, M.Kharitonievsky Str.,4., Russia</p>
<p><b>ABSTRACT</b><br>
An impedance-based approach is applied to the general fluid-structure interaction problem. For a passive finite-size lineally elastic body or structure of arbitrary configuration in fluid medium, the following new results are obtained. First, the range of allowable values of the sound power absorbed and scattered by the body is found, and a simple equation for the curve that bounds the range is derived. Second, explicit boundary conditions of the impedance type on the body surface are obtained for the limiting cases - for the most efficient absorber, the best scatterer, and for other bodies that possess extreme absorption and scattering properties. It is shown that the efficiency of the best absorber is several orders of magnitude higher than that of commonly used absorbers. Possible ways of achieving the extreme acoustic properties are discussed. Illustrative examples are presented.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p448.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p758" class="affilation"></a>Feedback Control of Piezo-Laminate Composite Plate</h2>
<h3>A. Yeilaghi Tamijani, M. Abouhamze, R. Mirzaeifar, A. R. Ohadi, M. R. Eslami</h3>
<p class="affilation">Department of Mechanical Engineering, Amirkabir University of Technology (Tehran Polytechnic), Hafez Ave, Tehran 15914, Iran</p>
<p><b>ABSTRACT</b><br>
Based on the applicability of smart materials in controlling the behaviour of engineering structures, a feedback control algorithm, which has been introduced previously by the authors, is implemented to control the dynamic response of composite laminates using bonded piezoelectric sensors and actuators. In order to investigate the shear transverse effect in the piezo-laminate and therefore be capable of analyzing thick plates, finite element formulation is derived based on higher order shear deformation theory of laminated plates. Finally, feedback control parameters, containing displacement and velocity gains, are changed and amplitude of dynamic response is thereby controlled. The numerical results show the effects of the different lamination angles on the vibration of plate. Furthermore, it is observed that how static deflection, natural frequencies and peak responses can be controlled by the displacement control gain and active damping can be provided by adjusting the velocity control gain.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p758.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p613" class="affilation"></a>Systematization of the Principles of Classification of Active Noise and Vibration Control Methods</h2>
<h3>Andrei V. Vassiliev</h3>
<p class="affilation">Department of Mechanics and Environmental Protection, Togliatti State University Togliatti, 445667, Belorusskaya Str., 14, Russia</p>
<p><b>ABSTRACT</b><br>
Active noise and vibration control presently is the important way to decide the problem of low-frequency noise and vibration reduction. Due to the rapid increase of books, papers and patents in this field, it is necessary to systematize the principles of classification of active noise and vibration control methods. Traditional and new approaches are investigated. The author proposes to use an energetic approach, according to which all methods and arrangements of reduction may be classified as completely passive (adaptive and nonadaptive), regenerative, active and hybrid passive-active. Other criteria include consideration of the spatial kind of low-frequency noise and vibration source, completeness of reduction, the type of spectrum, etc. The classification is illustrated by the different constructions of active noise and vibration control devices, mufflers and dampers, some of which are developed by the author.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p613.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p189" class="affilation"></a>Active Control of Free Beam Vibrations Utilizing Actuator Optimization</h2>
<h3>Ayman El-Badawy</h3>
<p class="affilation">Department of Engineering Mechanics, The German University of Cairo, New Cairo City, Al-Tagamoa Al-Khames, Egypt</p>
<p><b>ABSTRACT</b><br>
For this investigation, a collocated piezoceramic sensor/actuator pair to control the free vibrations of a pinned-pinned Euler-Bernoulli beam is used. The technique of positive position feedback control is employed; the piezo location and size is optimized. The control “goodness” is quantified by the total amount of damping to the different modes of the system.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p189.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p34" class="affilation"></a>An Actuator Fault Detection Concept for Active Vibration Control of a Heavy Metro Vehicle</h2>
<h3>Christian Benatzky, Martin Kozek</h3>
<p class="affilation">Institute of Mechanics and Mechatronics, Division of Control and Process Automation, Vienna University of Technology, Vienna, Austria</p>
<p><b>ABSTRACT</b><br>
This paper proposes a hardware redundancy based actuator fault detection concept for the control of a heavy metro vehicle car body. Because of the specific properties of collocated actuator/sensor pairs it can be shown that the proposed method is simple, reliable and inexpensive. Additionally, it avoids the necessity to accurately model the flexible structure under investigation which would be necessary in analytical redundancy based methods. Furthermore, the concept is validated utilizing a 1/10 scaled laboratory model of a heavy metro vehicle car body.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p34.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p812" class="affilation"></a>Optimisation of active and semi-active noise and vibration control systems</h2>
<h3>Colin H. Hansen, Xiaojun Qiu, Guillaume Barrault, Carl Q. Howard, Cornelis D. Petersen and Sarabjeet Singh</h3>
<p class="affilation">School of Mechanical Engineering
University of Adelaide
SA 5005
Australia</p>
<p><b>ABSTRACT</b><br>
Active and semi-active noise control system design may be considered to be multi-variable optimisation processes. The performance of the final design is a function of the order in which various aspects of the design are optimised as well as the optimisation process chosen for each aspect. Here, the optimal hierarchy for control is discussed first of all, followed by a discussion of the optimisation of various aspects of control system design. These aspects include: the physical arrangement of reference sensors, error sensors and control actuators; the choice of cost function; the choice of control system hardware architecture; and the choice of algorithm and associated parameters. The optimisation of these variables will be illustrated with examples of work currently being undertaken by the AVC group at the University of Adelaide.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p812.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p104" class="affilation"></a>Robust Stability in Feedback Active Noise Control</h2>
<h3>Damien Leclercq, Mike Kidner, Colin Hansen</h3>
<p class="affilation">School of Mechanical Engineering, The University of Adelaide, Adelaide, SA 5005, Australia</p>
<p><b>ABSTRACT</b><br>
A major hurdle in the design of a feedback system for active noise control applications is the difficulty in guaranteeing robust stability while maintaining adequate noise reduction performance. This requirement is particularly limiting when variations in the control plant response are large, as is the case with active headrests, where head movements can drastically modify the acoustic propagation between the control sources and error sensors, which affects both the magnitude and phase of the plant transfer function. It is possible, to some degree, to design a robustly stable controller that can accommodate plant variations within a range that is determined during preliminary laboratory measurements of all expected operational configurations. The robustly stable control filter is then designed by a computationally expensive optimisation procedure based on the assumed disturbance spectrum, the nominal plant response, and its expected maximum variation. However, plant variations are in some cases so large that it is not feasible to design a controller around a nominal plant response with a pre-determined uncertainty bound, and the nominal plant response needs to be characterised at various times during controller operation. This mode of operation is made possible by the appearance of control prototyping platforms constructed around powerful DSPs and equipped with considerable memory space. Although this does not allow the expensive optimisation to be carried out by the DSP, there is great potential to make robustly stable plants that can accommodate major variations in the system and primary disturbance. This paper presents the development of a feedback controller based on the internal model control architecture and evaluates the performance of various strategies to design an adaptive, feedback control filter that is robustly stable to variations in primary disturbance spectrum and plant transfer function.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p104.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p1" class="affilation"></a>Active Noise Control with a Virtual Acoustic Sensor in a Pure-Tone Diffuse Sound Field</h2>
<h3>Danielle J. Moreau, Justin Ghan, Ben S. Cazzolato, Anthony C. Zander</h3>
<p class="affilation">School of Mechanical Engineering, The University of Adelaide, SA 5005, Australia</p>
<p><b>ABSTRACT</b><br>
Local active noise control systems can be used to generate a zone of quiet at a physical error sensor using one or more secondary sources to cancel the acoustic pressure and its spatial derivatives at the sensor location. The resulting zone of quiet is generally limited in size and as such, placement of the physical error sensor at the location of desired attenuation is required, which is often inconvenient. Virtual acoustic sensors overcome this by projecting the zone of quiet away from the physical error sensor to a remote location. The work described here investigates the effectiveness of using virtual microphones and virtual acoustic energy density sensors in a diffuse sound field. Expressions for the performance of the virtual microphones and virtual acoustic energy density sensors have been developed using the forward-difference extrapolation technique which has been rederived for use in diffuse sound fields. Results from simulations will be presented, together with experimental results obtained in a reverberant chamber.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p1.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p161" class="affilation"></a>Moment Control of the Sound Radiated from an Axially Excited Cylindrical Shell</h2>
<h3>James A. Forrest</h3>
<p class="affilation">Maritime Platforms Division, Defence Science & Technology Organisation, PO Box 4331, Melbourne VIC 3001, Australia.</p>
<p><b>ABSTRACT</b><br>
This paper explores the feasibility of using moments to control the sound radiated from a small cylindrical shell. Previous theoretical work has shown that a circumferential line moment can provide good control of radiated sound in the first three axisymmetric axial modes of a water-loaded cylindrical shell representing a generic submarine. The results described here are part of a study that seeks to experimentally validate the theoretical result on a smaller scale in air. The steel shell considered is 1.5 m long, 400 mm in diameter and 2 mm thick. Its ends are capped by 20 mm thick circular steel plates. One end-plate would be driven by a shaker, with the proposed control moment provided by piezo stack actuators acting on a T-section ring-stiffener. The stack forces are modelled as two circumferential line forces, and a modal approach with cylindrical shell equations is used to calculate their optimum value to control sound radiation at axial resonance. Although some reduction in radiated sound from the shell in air is possible, the problem is complicated by the requirement for large control forces and a number of higher-order circumferential modes with resonances close to the axisymmetric ones being controlled.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p161.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p218" class="affilation"></a>Vibroacoustic Control of Honeycomb Sandwich Panels Using MFC Actuators</h2>
<h3>Jeng-Jong Ro (1), Hong-Yi Chou (1), Shuh-Jang Sun (2)</h3>
<p class="affilation">(1) Department of Mechanical and Automation Engineering, Dayeh University, Changhua, Taiwan 51505 (2) Chung-Shan Institute of Science & Technology, Tao-Yuan, Taiwan 90008</p>
<p><b>ABSTRACT</b><br>
New all-composite aircraft fuselage designs are being developed with a flexible honeycomb core sandwiched between carbon fiber reinforced composite laminate face sheets. The honeycomb sandwich panels offer potential advantages for significant weight reduction, while maintaining strength and fatigue properties. However, the excessive levels of vibration and noise of honeycomb sandwich panels have been a major cause for concern. Thus, vibration suppression and noise reduction in honeycomb sandwich panels pose major challenges for future aircraft design. In this research, vibroacoustic characteristics of honeycomb sandwich panels are experimentally examined in order to develop efficient and reliable vibroacoustic control mechanisms. The experimental measurements of vibroacoustic characteristics of honeycomb sandwich panels are validated using finite element model. Macro Fiber Composite (MFC), a newly developed piezoelectric actuator by the NASA LaRC, is typically directional or anisotropic, and more flexible and conformable as compared to a traditional monolithic isotropic piezoceramic actuator. The honeycomb sandwich panel is proposed as a test platform to demonstrate the effectiveness of MFC actuators in vibration suppression and noise reduction of honeycomb sandwich panel. Analytical prediction as well as experimental investigation are implemented to evaluate the effectiveness of vibroacoustic control of honeycomb sandwich panel with MFC actuators. The velocity feedback controller are utilized to determine appropriate voltage of the MFC actuators. The experimental results show 43% and 45% attenuation of first and second vibration modes with 25V and 40V velocity feedback voltages, respectively. Moreover, the results also demonstrate 72% attenuation of first mode of radiating noises with velocity feedback. The study suggests that using the MFC actuators in vibroacoustic control of honeycomb sandwich panel has been highly effective.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p218.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p216" class="affilation"></a>The Effect of Boundary Conditions on Active Control of Sound Radiation from a Rectangular Plate</h2>
<h3>Jingtao Du, Guoyong Jin, Tiejun Yang, Zhigang Liu, Wanyou Li</h3>
<p class="affilation">College of Power and Energy Engineering, Harbin Engineering University, Harbin, 150001, P. R. China</p>
<p><b>ABSTRACT</b><br>
This paper deals with the active control of sound radiation from a rectangular plate with general boundary condition. A baffled rectangular plate with elastic boundary restraints is subjected to a steady-state harmonic point force, and the resulting radiated sound field is minimized by applying point forces as control input. Modal parameters are obtained by employing an improved Fourier series method (IFSM) to construct a set of admissible functions for the Rayleigh-Ritz procedure. In conjunction with this method, vibration response is derived utilizing modal superposition theory. Velocity mobility curves from such method with those of analytical solutions for simply supported boundary case are compared. The agreements are excellent. The optimized control force is then calculated for global attenuation based on this model. The effects of boundary conditions on active control are shown and discussed through computer simulations mainly performed for two special cases.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p216.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p224" class="affilation"></a>A Geometric Approach to the Optimal Design of Remotely Located Broadband Vibration Control Systems</h2>
<h3>Jiqiang Wang, Steve Daley</h3>
<p class="affilation">Department of Automatic Control and Systems Engineering, The University of Sheffield, Mappin Street, Sheffield, S1 3JD, UK</p>
<p><b>ABSTRACT</b><br>
Over the past three decades, a wide variety of active control methods have been proposed for controlling problematic vibration. The vast majority of approaches make the implicit assumption that sensors or actuators can be located in the region where vibration attenuation is required. However, for many large scale structures or where the system environment is harsh, this is either not feasible or prohibitively expensive. As a result, the optimal control of local vibration may lead to enhancement at remote locations. Motivated by such problems in marine system environments, a geometric methodology that provides an approach for defining the design freedom available for reducing vibration both at local and remote locations has been previously been proposed by the authors. In an earlier paper, the fundamental results were used to develop design procedures for discrete frequency control; in the current paper, however, the focus is on design procedures for broadband control. A systematic approach is developed that provides an additional design constraint to the geometric methodology to ensure that the resulting compensator provides closed loop stability. The design procedure is illustrated using a test rig that has been built to replicate the problems associated with the control of rotor blade vibration.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p224.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p377" class="affilation"></a>Active Vibration Clamping Absorber Design</h2>
<h3>Ley Chen (1), Fangpo He (2), Karl Sammut (2)</h3>
<p class="affilation">(1) School of Mechanical Engineering, University of Adelaide, SA 5005, Australia (2) School of Informatics & Engineering, Flinders University, GPO Box 2100, SA 5001, Australia</p>
<p><b>ABSTRACT</b><br>
An active Vibration Clamping Absorber (VCA) technique for vibration suppression in flexible structures is proposed and investigated in this paper. The technique uses a Quadratic-Modal-Positive-Position-Feedback strategy to design a simple second-order nonlinear controller that is capable of suppressing structural vibrations at various resonances. The VCA can effectively transfer vibration energy from the main structure to another sacrificial absorber so that large amplitude vibrations in the main structure can be clamped within tolerable limits. The effectiveness of the VCA design is demonstrated through single-mode and multiple-mode control on a flexible cantilever beam system using one sensor/actuator pair. The theoretical analysis and experimental results reveal that the proposed design can be used for real-time control of vibration in large flexible structures.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p377.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p617" class="affilation"></a>Control of Vehicle Suspension Using Nonlinear Energy Sink Controller</h2>
<h3>Ling Zheng (1), Yinong Li (1), Amr Baz (2)</h3>
<p class="affilation">(1) Department of Automobile Engineering, Chongqing University, Chongqing 400044, China (2) Department of Mechanical Engineering, University of Maryland, College Park, MD 20742, USA</p>
<p><b>ABSTRACT</b><br>
The Nonlinear Energy Sink (NES) controller is designed and used to control actively or semi-actively the dynamics of vehicle suspension systems. A vertical vehicle dynamic model with seven degrees of freedom is developed and used to demonstrate the effectiveness of the NES controller. The proposed controller relies in its operation on specially designed nonlinear spring elements which are attached to the primary suspension system in order to induce optimal nonlinear vibration energy sinks. The obtained performance characteristics are compared with those of passive suspension and suspension using classical LQR controller. Simulation results show that the vibration energy transmitted by road disturbance has been successfully attenuated and the best possible ride comfort and handling performance can be potentially achieved by the proposed NES controller. It is also observed that the cost function of energy consumption using the NES controller is less than that using the LQR controller. The obtained results demonstrate the potential of the NES controller as an effective means for attenuating the vibration of vehicle suspension systems.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p617.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p197" class="affilation"></a>Design of Command Shaper Using gain-Delay Units and Particle Swarm Optimisation for Vibration Control of a Flexible System</h2>
<h3>M. S. Alam (1), M. A. Hossain (2), M. O. Tokhi (1)</h3>
<p class="affilation">(1) Department of Automatic Control and Systems Engineering, University of Sheffield, UK (2) School of Informatics, University of Bradford, UK</p>
<p><b>ABSTRACT</b><br>
Conventional command shaping method involves convolving a desired command with a sequence of impulses that may prove computationally expensive or unsuitable for a fast system. Moreover, a priori knowledge of the system parameters, such as resonance frequencies and associated damping ratios, is required to design the exact sequence of impulses to produce a command that results in zero residual vibration. A new command shaping method is proposed using gain and delay units to shape the reference input to reduce vibration of a flexible system. Assuming that, no prior information is available about the system, a new variant of particle swarm optimisation (PSO) algorithm is proposed and used to derive the gain values and the amount of delay. The effect of total number of delay and gain units is also analysed. A twin rotor system is used as the flexible system where the control strategy is applied and the results show the effectiveness of the proposed control strategy.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p197.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p283" class="affilation"></a>Active Control of Interior Noise in a Rectangular Cavity with Two Flexible Panels</h2>
<h3>Mohamed Gharib (1), Mohammad Tawfik (2)</h3>
<p class="affilation">(1) Cairo University, Aerospace Engineering Department, Giza, Egypt (2) Modelling & Simulation in Mechanics Department, Faculty of Engineering & Material Science, German University in Cairo, New Cairo City, Main Entrance Al Tagamoa Al Khames, Egypt</p>
<p><b>ABSTRACT</b><br>
In this work, a numerical effort is presented for modeling and control of structure-acoustics coupled systems. Modeling of sound transmission through a panel-cavity-panel system is presented. An approximate series solution is assumed and the solution is obtained using Galarkin’s method. The system to be modeled is consisting of a rectangular cavity with two flexible panels, one at the top of the cavity while the other at the bottom and four other fixed boundaries. PZT pair patches are considered to be bonded to the top panel and each pair is assumed to produce a pure moment actuation when an electric drive signal is used to excite them. The flexible panel is exposed to an external pressure excitation due to a planar wave generated by a sound source mounted above the cavity. Displacements at the mid points are calculated for the upper and lower panels. The developed model is controlled using the optimal LQR control law. The numerically obtained time responses from the compensated model are found to be acceptable compared to the uncompensated ones. It is found that the actuation of the upper panel can decrease the vibration of the lower one rather than decreasing the acoustic pressure inside the cavity.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p283.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p232" class="affilation"></a>Optimal Control of a Pretwisted Tapered Rotating Beam with Tip Rotor</h2>
<h3>Naresh K. Chandiramani (1), Liviu Librescu (2)</h3>
<p class="affilation">(1) Department of Civil Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India (2) Department of Engineering Science and Mechanics, Virginia Tech, Blacksburg, VA 24061-0219, USA</p>
<p><b>ABSTRACT</b><br>
Active control of a thin-walled rotating beam with pretwist, double-taper, and a tip rotor, is considered using the higher-order shear deformation theory (HSDT). The beam comprises an orthotropic host with surface-embedded transversely isotropic (PZT-4) sensor-actuator pairs. Span-wise and thickness-wise variation is considered for the electric field applied to actuators. This yields a coupled electro-mechanical system, wherein displacement variables are coupled via the electric field. Optimal LQR control with state feedback is used to obtain the control input (charge density applied to actuators). Parametric studies involving ply-angle, rotation speeds of beam and rotor, pretwist, taper, rotor mass, and saturation constraint on actuator voltage, are performed. The present model yields an order-of-magnitude reduction in settling time and control voltage/power, and lower response, vis-a-vis the decoupled approach.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p232.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p373" class="affilation"></a>Adaptive Control of an Mr Mount for Vibration Attenuation</h2>
<h3>R. Pan, Y. C. Chang, J. Shaw</h3>
<p class="affilation">Institute of Mechatronic Engineering, National Taipei University of Technology, No.1, Sec.3, Zhongxiao E. Rd., Taipei 106, Taiwan</p>
<p><b>ABSTRACT</b><br>
In this paper, an MR mount with flow mode operation is studied for vibration suppression subject to base excitations. Recently, magneto-rheological (MR) fluid has become a popular material for actuator use. There are some good properties associated with MR fluid such as the reversible, controllable, and continuous change of rheological characteristics upon application of magnetic field. However, the dynamic equation of MR mount is highly nonlinear, hence making the controller design an extremely difficult task. This paper aims to develop a semi-active control technique for suppressing vibration of an MR mount subject to its base disturbances. The adaptive control scheme is employed for vibration attenuation. Function approximation technique is used here to represent the unknown system dynamics including the external disturbance in some finite linear combination of the orthogonal basis. The dynamics of MR mount system can thus be proved to be a stable first order filter driven by function approximation errors. Moreover, the adaptive update law can be obtained by using the Lyapunov stability theory. The well-known skyhook control scheme and a controller with constant applied magnetic field are to be compared with the proposed adaptive controller for semi-active vibration control of the MR mount.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p373.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p524" class="affilation"></a>Multi-Channel Adaptive Vibration Control of Smart Plate Using Hybrid Algorithm</h2>
<h3>Seyyed M. R. Hashemi, A. R. Ohadi</h3>
<p class="affilation">Mechanical Engineering Department, Amirkabir University of Technology (Tehran Polytechnic), Tehran, Hafez Ave. 424, Iran</p>
<p><b>ABSTRACT</b><br>
The aim of this paper is simulation of multiple-channel adaptive vibration control of a clamped elastic plate with PZT sensors/actuators using hybrid algorithm. Finite element method is used for plate modelling. In the presented model, mass and stiffness of the PZT patches are considered. Transfer functions between exciting input and reference sensor, error sensors and reference sensor, actuators and reference sensor and also between actuators and error sensors have been determined by harmonic analysis via FE model. These transfer functions have been determined as IIR filters in z-domain. Off-line identification of secondary paths (from actuators to error sensors) and feedback paths (from actuators to reference sensor) have been carried out by using adaptive FXLMS identification method. Finally, for Single-Input-Multi-Output (SIMO) smart plate, the hybrid active vibration control is simulated and performance of the controller for globally vibration suppression is studied. The performance of the hybrid and feeforward controllers is compared. Obtained results indicate that the efficiency of the controller is dependent to the places of error sensors and actuators and frequency content of the exciting force.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p524.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p143" class="affilation"></a>Robust Feedback Disturbance Rejection for Sound-Structure Interaction Systems Using Optimal Sensor - Actuator Location</h2>
<h3>Suwit Pulthasthan, Hemanshu Pota</h3>
<p class="affilation">School of Information Technology and Electrical Engineering, University of New South Wales at Australian Defence Force Academy, ACT 2600, Australia</p>
<p><b>ABSTRACT</b><br>
This paper presents a practical method and novel work of robust disturbance rejection for sound-structure interaction systems using optimal sensor-actuator location. The applicability of this method is to systems with non-ideal boundary conditions as in the case of practical engineering applications. An experimental acoustic cavity with five walls of timber and a thin aluminium sheet fixed tightly on the cavity mouth is chosen in this paper as a good representation of general sound-structure interaction systems. The sheet is intentionally so fixed that it does not satisfy ideal boundary conditions. The existing methods for obtaining optimal sensor-actuator location using analytic models with ideal boundary conditions are of limited use for such problem with non-ideal boundary conditions. The optimal placement of actuator and sensor is obtained from novel criteria using energy based approach and model uncertainty. The optimal actuator-sensor location obtained is used to construct a robust feedback disturbance rejection using minimax LQG control design method. Practical aspects of the method of the robust feedback disturbance rejection using optimal sensor-actuator location are highlighted by experimental results of vibration and acoustic noise attenuation for arbitrary disturbance. The disturbance is experimentally set to enter the system via a spatial location different from the controller input like any practical applications of feedback disturbance rejections. Experimental demonstration of the novel methods presented in this paper attenuates structural vibration up to 17 dB.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p143.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p316" class="affilation"></a>Evaluation Methodology of the Technical Condition of a Power Transformer Based on the Measurement Results of Mechanical Vibrations of its Tub</h2>
<h3>Tomasz Boczar, Marcin Lorenc, Dariusz Zmarzły</h3>
<p class="affilation">Opole University of Technology, Faculty of Electrical Engineering Automatic Control and Computer, Science, Opole, Mikołajczyka 5, 45-271, Poland</p>
<p><b>ABSTRACT</b><br>
The subject matter of this paper refers to vibroacoustic measurements of high power transformers. The evaluation method of the transformer technical condition, based on the measurements of mechanical vibrations of its tub, is characterized. The elements of the measuring set-up, which were used during the registration of the signals coming from the core and winding vibrations of a given transformer unit, transferred by the tub, are presented. Based on the criterion values of the vibroacoustic parameters measured: root-mean-square value of the vibration acceleration and the vibration spectrum amplitude in the frequency range from 0 to 3000 Hz, the evaluation of the technical condition of the power appliance under study was carried out.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p316.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p314" class="affilation"></a>Wavelet Analysis of the Power Transformer Tub Vibrations</h2>
<h3>Tomasz Boczar, Marcin Lorenc, Dariusz Zmarzły</h3>
<p class="affilation">Opole University of Technology, Faculty of Electrical Engineering Automatic Control and Computer, Science, Opole, Mikołajczyka 5, 45-271, Poland</p>
<p><b>ABSTRACT</b><br>
The paper will present the wavelet analysis results using continuous and discrete wavelet transforms of vibrations of a power transformer tub installed on the block of a conventional, thermal condensation power station. The research tests were carried out during a regular transformer operation in industrial conditions. The measurements were taken from the point of view of the evaluation of the influence of the vibrations registered on the analysis results of the acoustic emission signals generated by partial discharges that can occur in paper-oil insulation systems of power transformers. Moreover, the analyses carried out were supplemented with the research results obtained in laboratory conditions during the measurements taken in the high-voltage testing station of high-voltage power appliances. The influence of the loosened screws fastening the lid of the transformer tub on the time-frequency analysis results obtained of the vibrations registered was investigated. Moreover, the range of the research work carried out referred to the evaluation of the influence of the changes of the pressure force of the metal plates forming the transformer core on the vibration measurement results were obtained. In summary, the evaluation of usefulness was presented and the range of the time-frequency analysis application possibilities, and especially wavelet transforms, in diagnostics of power transformers using the acoustic methods was characterized.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p314.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p139" class="affilation"></a>Optimization in Active Non-Stationary Random Vibration Control for Smart Truss Structures with Uncertainty</h2>
<h3>Wei Gao (1), Liyong Tong (2)</h3>
<p class="affilation">(1) Mechatronics and Intelligent Systems, Faculty of Engineering, University of Technology, Sydney NSW 2007, Australia (2) School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, Sydney NSW 2006, Australia</p>
<p><b>ABSTRACT</b><br>
This paper presents the reliability-based optimization of the location and feedback gains of a piezoelectric active bar in a closed loop control system for smart truss structures with random parameters under non-stationary random excitation. The mathematical model with reliability constraints on the mean square value of the structural random dynamic displacement and stress response is developed based on maximization of dissipation energy due to the control action. The randomness of the structural physical materials and geometry are included in the analysis, and the applied forces are considered as non-stationary random excitation. Numerical examples of smart truss structures are presented to demonstrate the active control model.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p139.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p589" class="affilation"></a>Nonlinear Control of a One Axis Magnetic Spring</h2>
<h3>Will S. Robertson, Ben S. Cazzolato, Anthony C. Zander</h3>
<p class="affilation">School of Mechanical Engineering, The University of Adelaide, SA 5005, Australia</p>
<p><b>ABSTRACT</b><br>
This paper presents the initial investigation of nonlinear control for a magnetic spring. The combination of a magnet pair in repulsion and a magnet pair in attraction create a spring with a quadratic force curve. At its nominal position, it is a marginally stable system that has interesting vibration isolation properties. Non-linear control is shown to be effective in stabilising the system.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p589.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p140" class="affilation"></a>Multidelay Adaptive Filters for Active Noise Control</h2>
<h3>Xiaojun Qiu (1), Colin H. Hansen (2)</h3>
<p class="affilation">(1) Key Laboratory of Modern Acoustics and Institute of Acoustics, Nanjing University, China 210093 (2) School of Mechanical Engineering, University of Adelaide, South Australia 5005, Australia</p>
<p><b>ABSTRACT</b><br>
There are two ways to implement frequency domain filtered x LMS (FXLMS) algorithms. The first carries out both control signal generation and control filter updating in the frequency domain, and the second involves implementation of the control filtering in the time domain and updating of the coefficients of the control filters in the frequency domain. Most active noise control literature is focused on the second approach as the first one introduces a delay of at least one FFT block size for the control filter generation, which is usually not acceptable for active noise control. However, the second implementation has a limitation on its maximum computational complexity reduction due to its delayless requirement and it also needs quite a large on-chip memory for its FFT. The multidelay adaptive filter to be discussed in this paper is intended to solve some of the above problems. The multidelay adaptive filter has a flexible structure, which partitions a long filter into many shorter sub-filters so that a much smaller FFT size can be used to reduce the delay and memory requirement while maintaining the low computational complexity and faster convergence properties of the frequency domain algorithm.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p140.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p449" class="affilation"></a>Sound Radiation from a Buried Nozzle with Jet and Bypass Flow</h2>
<h3>A. Demir, S.W. Rienstra</h3>
<p class="affilation">Department of Mathematics & Computer Science, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands</p>
<p><b>ABSTRACT</b><br>
Radiation of sound from a simplified model of a buried nozzle with bypass flow is studied. More precisely, a semi-infinite duct (the inner nozzle) is situated inside a larger semi-infinite duct. The exit plane of the larger duct either coincides with the exit plane of the smaller duct, or extends beyond it. Differences in the piece-wise subsonic mean flow velocity, density and temperature are taken into account. The inner nozzle issues the core flow inside the bypass jet flow. The bypass nozzle issues the bypass jet flow inside the ambient co-flow. Two vortex sheets, attached to the duct exits, separate the different flows from each other. These vortex sheets are unstable due to this mean velocity discontinuity. The application of the Kutta condition at the respective trailing edges guarantees shedding of vorticity which excites these instabilities. The system is set up to respond to an incident annular duct mode, but the analysis would be very similar for an inner duct mode. To obtain an analytical solution aWiener-Hopf approach with Idemen’s method of “weak factorisation” is applied. Formulation of the boundary value problem following the classical approach leads to a couple of simultaneous Wiener-Hopf equations. These equations produce a matrix equation system, which is formally decoupled by the introduction of an infinite sum of poles with coefficients to be determined. The uncoupled scalar equations are solved independently by a standard application of analytical continuation. The unknown coefficients in the final solution are determined by solving an infinite linear algebraic system numerically. The contribution of the instability waves are separated from the rest of the solution. The asymptotic far field is found by a standard application of the steepest descent method. Finally a series of practical examples are given.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p449.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p461" class="affilation"></a>Turbomachinery Noise Radiation Through the Engine Exhaust (TURNEX)</h2>
<h3>B. J. Tester</h3>
<p class="affilation">Institute of Sound and Vibration Research, University of Southampton, Southampton, SO17 1BJ, United Kingdom</p>
<p><b>ABSTRACT</b><br>
TURNEX (Turbomachinery Noise Radiation through the Engine Exhaust) is a 6th Framework European-funded project comprising a consortium of 12 partners, coordinated by the ISVR, and is aimed at an improved understanding and a reduction of turbomachinery noise radiation through the jet exhaust. The project spans three years (2005-2007). Turbomachinery noise radiating from the bypass and core nozzles is becoming the dominant noise source on modern aircraft, but, while recent EU research programmes have made significant progress in reducing both the generation of turbomachinery noise and the radiation of noise from the intake, little work has been conducted on reducing the radiation of turbomachinery noise from exhaust nozzles. TURNEX will address this shortfall by delivering improved understanding and validated design methods, and by evaluating a number of low-noise exhaust nozzle configurations aimed at a source noise reduction of 2-3 dB. The main achievements at the end of the second year are described here, which include experimental test results and verification of CAA solutions with analytical solutions for radiation of duct modes through different types of exhaust jet flows.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p461.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p131" class="affilation"></a>Internal Accoustic Excitation to Enhance the Airfoil Performance at High Reynolds Number</h2>
<h3>Benjamin Ahn, N.A. Ahmed</h3>
<p class="affilation">School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney, NSW 2052, Australia</p>
<p><b>ABSTRACT</b><br>
The ability to force air flow to follow the contour of a given lifting surface, even under the adverse pressure flow gradient, plays a significant role in optimizing the performance of lifting surface. As the angle of attack (α) increases large portion of the lifting surface will not see the flow due to the separation occurring closer to the leading edge. This creates an unsteady wake which results in loss of lift and increase in drag. In order to minimize the boundary layer separation, additional energy must be given to a low momentum fluid in the very near-wall region. It has been found that acoustic-vibration energy, which introduces periodic energy input, delays flow separation. The approach presented herein employs acoustic and vibration excitation. Two designs were constructed and experimented upon using the 0.76 m open jet open circuit subsonic wind tunnel at the University of New South Wales, with results showing potential to reduce flow separation. In the present study, speakers were used as means of internal excitation to vibrate the NACA 0015 wing. Various frequencies were applied on the top surface of the wing by the internally attached speakers. When the flow was excited at a favourable frequency, the flow separation was suppressed, and delay in stall angle of attack (α<sub>stall</sub>) was found to occur. Further, the relationship between the excitation frequencies (f<sub>e</sub>), shedding frequencies (f<sub>s</sub>) and the Strouhal numbers (S<sub>r</sub>) was found.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p131.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p438" class="affilation"></a>Beamforming in Highly Reverberant Wind Tunnels Possibilities and Limitations</h2>
<h3>Benjamin Fenech, Kenji Takeda</h3>
<p class="affilation">School of Engineering Sciences, University of Southampton, SO17 1BJ, UK</p>
<p><b>ABSTRACT</b><br>
Closed-section hard-walled wind tunnels are routinely used for aerodynamic testing during the early stages of vehicle design. The use of microphone arrays and beamforming processing in such environments can yield useful source localisation information; yet there are concerns as to the consistency of quantitative results from such methods when compared to anechoic openjet tunnel testing. Higher background noise levels, microphones in contact with the turbulent boundary layer, and the highly reverberant nature of the measuring environment are of particular concern. In this paper we show that accurate results in closed-section wind tunnels are still possible using the cross-spectral matrix diagonal removal (DR) technique, and with dereverberation. With DR, improvements in beamformer’s accuracy up to 10 dB can be achieved when compared to standard beamforming. De-reverberation gives an additional 10 dB improvement, and provided that the noise contamination to the microphone pressure data is somewhat suppressed, errors within ±1dB can be expected. Both of these methods do not require any additional changes to the physical infrastructure of the measuring environment.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p438.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p288" class="affilation"></a>Three-Dimensional Predictions of the Rod Wake-Airfoil Interaction Noise by Hybrid Methods</h2>
<h3>Björn Greschner (1), Sven Peth (1), Young J. Moon (2), Jung H. Seo (2), Marc C. Jacob (3), Frank Thiele (1)</h3>
<p class="affilation">(1) Berlin University of Technology, Institute of Fluid Mechanics and Engineering Acoustic, Mueller-Breslau-Str. 8, D-10623 Berlin, Germany (2) Korea University, Department of Mechanical Engineering, 1 Anam-dong, Sungbuk-ku, Seoul, 136-701, Korea (3) Ecole Centrale de Lyon, Centre Acoustique du LMFA-UMR CNRS 5509, 36, avenue Guy de Collogne, F-69134 Ecully, France</p>
<p><b>ABSTRACT</b><br>
Sound generated by an airfoil in the wake of a rod is predicted numerically by two different hybrid CFD/CAA approaches (Ma = 0.2). The configuration is a symmetric airfoil one chord downstream of a rod, whose wake contains both periodic and broadband vortical fluctuations. In particular, a significant broadening of the main Strouhal peak has been observed at subcritical vortex shedding conditions. This study addresses the overall ability of both CFD/CAA hybrid approaches to model broadband noise sources. The first approach computes the aerodynamic noise by solving the linearized perturbed compressible equations (LPCE) for the noise propagation, with the acoustic sources and hydrodynamic flow variables computed from the incompressible Large Eddy Simulation (iLES) using a computional grid of approximately 3 million grid cells and high-order compact finite difference schemes. The second approach uses the unsteady aerodynamic field of a compressible Detached Eddy Simulation (DES) and a Ffowcs Williams & Hawkings (FW-H) acoustic analogy formulation for the farfield noise calculations. The non-zonal DES approach solves either the unsteady Reynolds-averaged or spatially filtered Navier-Stokes equations by using a novel cubic explicit algebraic stress turbulence model based on a two-equation k-e model by Lien and Lechziner. An implicit formulation is used with second order accuracy and a grid of approximately 2.3 million cells. The results of these hybrid approaches are compared and subsequently validated with the measurements of Jacob et al. in the nearfield (HWA) and in the farfield (noise).</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p288.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p47" class="affilation"></a>Aeroacoustic Computations of a Counter-Rotating Fan</h2>
<h3>Cyril Polacsek, Raphael Barrier</h3>
<p class="affilation">Office National d’Etudes et de Recherches Aérospatiales, Departments of Numerical Simulations & Aeroacoustics and Applied Aerodynamics, 29, avenue de la Division Leclerc, 92322 Châtillon Cedex, France</p>
<p><b>ABSTRACT</b><br>
Aeroacoustic simulation of interaction noise generated by a contrafan model is proposed in this paper, in the framework of European Project VITAL (EnVIronmenTALly friendly aeroengine). Main objective here is to check the ability of advanced computations, including noise generation, propagation and radiation, to give a reliable evaluation of an innovative concept. Numerical simulations are realized by using a hybrid method based on the coupling of CFD (Computational Fluid Dynamics) and CAA (Computational Aero-Acoustics) ONERA codes. The matching between CFD and CAA is based on a Fourier-Bessel mode expansion of the perturbation field along a prescribed cross-section, from which outgoing modes then are traduced, in an original way, as source terms in the CAA. In-duct mode power and spectrum at the outer-wall are analyzed and discussed by comparison with theory and with similar results from project partners. Acoustic far field radiated by inlet and deduced from Kirchhoff integration is addressed in terms of mode spectrum and directivities. These first predictions are to be compared to experimental data soon available.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p47.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p105" class="affilation"></a>Development and Validation of a Small-Scale Anechoic Wind Tunnel</h2>
<h3>Damien Leclercq, Con Doolan, Jochen Reichl</h3>
<p class="affilation">School of Mechanical Engineering, The University of Adelaide, Adelaide, SA 5005, Australia</p>
<p><b>ABSTRACT</b><br>
After more than half a century of intense activity and the considerable development of complex numerical models, aeroacoustic research still relies heavily on experimental approaches. Experiments are essential to provide reference data for fundamental test cases, to understand highly complex and interacting phenomena, and to validate numerical simulations. At the University of Adelaide, the School of Mechanical Engineering is undertaking the upgrade and optimisation of its small-scale wind tunnel to support its increasing research activity in aeroacoustics. An experimental programme to start in 2007 requires a quiet 75 x 300 mm<sup>2</sup> rectangular cross-section jet with a maximum flow speed of 30 m/s, in an enclosure that is anechoic at frequencies above 200 Hz. This paper gives a brief outline of the process followed to upgrade the wind-tunnel, including the air supply system, flow treatment and jet cross-section. Additionally, the flow properties and acoustic performance of the wind tunnel are assessed through a series of validation experiments, and the main results are presented here against the initial design objectives. The results of a simple experiment consisting of a cylinder in cross-flow are also presented, and initial results are compared with a semiempirical model to demonstrate the performance of the wind tunnel. Finally, a brief outline of the subsequent research work to be carried out in the wind tunnel is given.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p105.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p236" class="affilation"></a>A Review of Selected Experimental Investigations of Curle’s Theory</h2>
<h3>David Alan Bies (1), Alexei Zinoviev (2)</h3>
<p class="affilation">(1) 103 Callaghan St, Mooroobool, Cairns, QLD 4870, Australia. (2) School of Mechanical Engineering, University of Adelaide, North Tce, Adelaide, SA 5005, Australia.</p>
<p><b>ABSTRACT</b><br>
Curle published an article, widely known as Curle’s theory, in which he sought to extend the theory of Sir James Lighthill on aerodynamic noise generation to include the effects of rigid boundaries. His theory has been accepted as mathematically correct and has been widely referenced, but it remains without experimental verification. A review of five selected articles published over a span of 35 years reporting experimental investigations of Curle’s theory will be presented. The review will show that, in cases where the source is compact, Curle’s theory predicts radiated sound power about 5 dB too high, while in non-compact cases Curle’s theory predicts radiated sound power about 5 dB too low. These observations are readily explained and the explanation suggests why Curle’s theory has not been experimentally verified but, more importantly, what may require further consideration. In the cases investigated Curle’s failure to consider source structure is shown to be responsible for the observed disparities. The disparate results may be explained if in the case of non-compact wave numbers the dominant noise source is a surface source distribution proportional to the square of the dimensionless wave number, while at compact wave numbers the latter source tends to insignificance and a less efficient leading edge dipole independent of the dimensionless wave number is then dominant.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p236.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p645" class="affilation"></a>Two- and Three-Dimensional Coupling in the Noise Prediction of the Edge Tone</h2>
<h3>Istvan Vaik (1), Irfan Ali (2), Max Escobar (3), Manfred Kaltenbacher (3), Stefan Becker (2), György Paál (1)</h3>
<p class="affilation">(1) Department of Hydrodynamic Systems, Budapest University of Technology end Economics, P.O. Box 91, H-1521 Budapest, Hungary (2) Institute of Fluid Mechanics, University of Erlangen-Nuremberg (3) Department of Sensor Technology, University of Erlangen-Nuremberg</p>
<p><b>ABSTRACT</b><br>
The reduction of noise in our everyday life requires the understanding of its generation and propagation. Aeroacoustic sources are among the most complicated noise sources and their simulation still presents a challenge. In this paper recent results of the developed numerical aero-acoustic simulation algorithm are presented. A commercial CFD code was used to carry out high precision unsteady flow simulations in 2D for the well known low Mach number edge tone flow field. Adopting Lighthill’s analogy, noise sources were calculated from the flow field and then an in-house acoustic code was used to compute the acoustic field. The acoustic calculations were performed in the frequency domain. Several kinds of coupling of the two codes were tried: 2D flow - 2D acoustics, 2D flow - 3D acoustics and 3D flow - 3D acoustics simulations. Comparisons of the various couplings are presented, as well as comparisons with recent time domain simulations.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p645.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p431" class="affilation"></a>Aft Fan Noise Reduction with a Lined Afterbody</h2>
<h3>L. De Mercato, B. J. Tester, K. Holland</h3>
<p class="affilation">Institute of Sound and Vibration Research, University of Southampton, Southampton, SO17 1BJ, United Kingdom</p>
<p><b>ABSTRACT</b><br>
Aft fan noise is becoming a more dominant source as engine bypass ratio is increased and improved methods are required for its control. Bypass liners are especially effective in attenuating aft fan noise, but, in a recent paper we introduced the idea of using acoustic linings on external parts of the aero-engine nacelle, such as the afterbody and plug nozzle. We conducted tests on a ‘No-flow’ rig with a broadband noise source, using scaled, linear SDOF acoustic linings to simulate the conventional, internal bypass liners and also the new external Afterbody Liner (AL). We showed that when the afterbody is acoustically lined, it reduces the far field sound power by up to 3 dB, a result which was confirmed with calculations using a commercially available CAA code. In this paper, we extend the previous broadband tests to include tone noise using an array of loudspeakers in the No-flow rig to excite specific modes. The measured tone reduction data are compared with calculations and the performance of AL is assessed relative to that achieved with the conventional bypass liners. The results confirm our expectations that the AL could also provide significant reductions in aft fan tonal fan noise levels. However, it should be emphasised that the results obtained so far are without mean flow and have to be confirmed by numerical simulations and tests with flow.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p431.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p404" class="affilation"></a>Comparison of Numerical Approaches for the Simulation of Sound Radiation from a Scarfed Inlet</h2>
<h3>Lukasz Panek (1), Norbert Schönwald (1), Frank Thiele (1), Michael Dumbser (2), Claus-Dieter Munz (2)</h3>
<p class="affilation">(1) Institute of Fluid Mechanics and Engineering Acoustics, Berlin University of Technology, D-10623 Berlin, Germany (2) Institut für Aerodynamik und Gasdynamik, Universität Stuttgart, Stuttgart, Germany</p>
<p><b>ABSTRACT</b><br>
In recent decades great effort has been made to reduce the noise emission of aero-engines. Due to increasing bypass ratios the fan area in aero-engines has become larger. This development is advantageous for the efficiency and the reduction of jet noise, however, it relocates the noise problem to the engine intake. In the presented work two different numerical approaches for solving the linearised Euler equations (LEE) will be compared. Their application to the case of sound propagation in the JT15D aero-engine intake will be presented. The fist method, also called the Chimera-technique, is based on overlapping structured grids which exchange data using high order interpolation. It employs the well-known high order Dispersion Relation Preserving scheme (DRP) for the spatial discretisation and an optimised Runge-Kutta Method for temporal integration. The second method is based on unstructured tetrahedral meshes and uses a new version of explicit one-step Discontinuous Galerkin (DG) Finite Element schemes allowing for arbitrary high order of accuracy in space and time as well as for time accurate local time stepping (LTS). Both high order methods are optimised for sound propagation and are capable of simulating complex geometries such as a scarfed nacelle intake including the spinner. The first objective of this work is to gain insight into the acoustic far field characteristics of an intake in the presence of a realistic mean flow. Furthermore, the influence of an asymmetrical shape of the inlet mouth will be studied. The second objective is to compare the different numerical methods with respect to their accuracy and computational efficiency, this being a major criterion for industrial application.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p404.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p527" class="affilation"></a>Aeroacoustic Investigation of a Tip Clearance Flow</h2>
<h3>Marc C. Jacob (1), Julien Grilliat (1), Michel Roger (1), Roberto Camussi (2)</h3>
<p class="affilation">(1) Laboratoire de Mécanique des Fluides et d’Acoustique (LMFA), UMR CNRS 5509, Université, Claude-Bernard Lyon I, Ecole Centrale de Lyon,, 69134 Ecully Cedex, France (2) Mechanical and Industrial Engineering Dept. (DIMI), University ‘Roma 3’, Rome, Italy</p>
<p><b>ABSTRACT</b><br>
Strong unsteady broadband perturbations are found in a tip clearance flow and related to acoustic radiation using standard techniques as well as advanced cross-wavelet analysis. The experiment is carried out on a single non-rotating airfoil in the anechoic wind tunnel facility of the Ecole Centrale de Lyon. The airfoil is placed between two plates into a Mach 0.2 openjet flow. A strong leakage flow is obtained with a high lift, 5% camber airfoil at a 15° angle of attack. The leakage flow occurs in an adjustable gap between the lower plate and the airfoil tip and the sound radiated into the cross-stream direction is measured in a medium at rest. The influence of the gap size is investigated. PIV measurements are carried out both around the airfoil and in the gap region providing a detailed view of the flow. Unsteady pressure measurements on the airfoil, both in the mid-span region and in the gap region, are combined with single HWA and PIV measurements. A special care is given to placing the probes on the tip of the airfoil, the tip edges and the plate facing the tip. Moreover, 2 sets of probes are installed in the mid-span region both spanwise and chordwise near the trailing edge. An advanced wavelet analysis of the pressure fields allows to identifying the aeroacoustic sources and to relate them to turbulent eddies generated in the gap region.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p527.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p165" class="affilation"></a>The Role of the Inflow Momentum Thickness in Subsonic Cylindrical Cavity Noise Generation</h2>
<h3>Marco Grottadaurea, Aldo Rona</h3>
<p class="affilation">Department of Engineering, University of Leicester, Leicester, LE1 7RH, United Kingdom</p>
<p><b>ABSTRACT</b><br>
At typical landing speeds, the cylindrical cavity ow that develops past an aircraft fuel vent displays tonal convective streamwise instabilities. The higher frequency range of the noise radiated by such a cavity compared to ap noise is perceived by a ground observer as louder with respect to what its amplitude in decibel would suggest, due to the dB(A) weighting. A three-dimensional time-dependent numerical model of a cylindrical cavity ow is obtained using an in-house three-dimensional compressible laminar solver. This simulation predicts the ow instability and gives a preliminary understanding of the influence of the inflow momentum thickness (θ) on the ow unsteadiness. Time-dependent cavity ow models are obtained at two different Reynolds numbers (Re<sub>θ</sub>) based on the inflow momentum thickness, Re<sub>θ</sub> = 8850 and Re<sub>θ</sub> = 10750, for two diameter to depth ratios (L/D), 0.71 and 2.5. The near-field sound pressure level (SPL), the pressure coefficient Cp, and the shear layer spanning the cavity are analyzed. The numerical experiments suggest that the deep cavity is characterized by a self-sustained instability and that the shallow cavity is characterized by a steady ow recirculation. The near-field SPL was compared with past Euler predictions to study the inuence of the shear layer growth on the radiating pressure field. In the laminar predictions, it was found that the amplitude of the outgoing pressure waves is lower, due to a weaker interaction of the open cavity shear-layer with the downstream solid edge.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p165.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p629" class="affilation"></a>Laminar Boundary Layer Instability Noise Produced by an Aerofoil</h2>
<h3>Michael Kingan, John Pearse</h3>
<p class="affilation">Department of Mechanical Engineering, University of Canterbury, Christchurch, New Zealand</p>
<p><b>ABSTRACT</b><br>
When a laminar boundary layer exists on the surface of an aerofoil up to the trailing edge, a tone of a number of tones are sometimes produced. These tones have been the subject of a number of investigations which have proposed a variety of different mechanisms regarding their production of a theoretical model to estimate the tone frequencies. The model is validated against experimental results for two cases.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p629.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p362" class="affilation"></a>Numerical Investigation of Aerodynamic Sound Radiated from a Bluff Body Using Lighthill Tensor</h2>
<h3>Shoji Kato (1), Hiroshi Muraoka (2), Yuta Takahashi (2), Tubagus Haedar (2), Akiyoshi Iida (1)</h3>
<p class="affilation">(1) Kogakuin University, 2665-1 Nakanomachi. Hachioji-shi, Tokyo, 192-0015, Japan (2) Research Center of Computational Mechanics, Inc., Togoshi NI-Bldg. 1-7-1 Togoshi, Shinagawa-ku, Tokyo, 142-0041, Japan</p>
<p><b>ABSTRACT</b><br>
Verifying the effectiveness of Lighthill tensor’s application coupled with both Finite Element Method (FEM) and Infinite Element Method (IEM) for aero acoustic scattering analysis was the main purpose of this research. The Lighthill tensor is classified as the real source of aerodynamic sounds being generated within a fluid domain and understanding its nature is critical in terms of noise reduction during a product development phase. In order to evaluate both sound pressure strength and propagation pattern, aeroacoustic fields surrounding a rectangular cylinder placed in a uniform flow was tested. Lighthill tensor was taken from CFD (Front Flow/Blue, FLUENT) calculation and the outcome was compared to ones using Boundary Element Method (BEM) analysis based on reduced Curle’s equation along with wind tunnel experimental data. The main sound source was seen near the trailing edge of the cylinder at approximately 1-2 times the length of the rectangle’s side. Although significant margins between the three methods were observed at low frequency, beyond 100Hz, the characteristic of sound pressure strength were closely matched. It became evident that if consideration regarding directivity or the aerodynamic sound source scattering needed to be taken into account, ACTRAN (Lighthill tensor calculation in the domain) application was more prominent than utilizing reduced Curle’s equation (pressure on the surface).</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p362.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p137" class="affilation"></a>A Source Term Formulation for the Non Linear Euler Equations in a Conservative and Perturbation Form</h2>
<h3>Stéphane Redonnet, Daniel Mincu, Marc Terracol, Eric Manoha</h3>
<p class="affilation">CFD and Aeroacoustics Departement, ONERA (French Aerospace Center), Bp 72, 29 av. de la Division Leclerc, 92322 - Châtillon, France</p>
<p><b>ABSTRACT</b><br>
The numerical simulation of aerodynamic noise is a complex task that can hardly be conducted through a single method / solver. Thus, one generally uses hybrid techniques that associate CFD and CAA computations, the latter being devoted respectively to the generation and the propagation of acoustics events. Such a methods / solvers association requires a coupling that can be achieved by two distinct approaches; the first one is the “surfacic coupling” that was initially developed at ONERA, and successfully applied within the framework of airframe noise. However, such a coupling presents some drawbacks that may render it inapplicable to realistic (and, thus, complex) configurations. Then, recently, another approach has been investigated, which is the “volumic coupling” technique. If such an technique is potentially more promising than the previous one, it however asks for more formulation / implementation work. In particular, it requires the establishment of a source term that can suit the CAA formulation and solver to be used with. In the present case, it then was necessary to derive a proper source term for the specific formulation (Conservative, Perturbed, Non linear Euler’s equations) and numerical tool (sAbrinA) that are used at ONERA for all the CAA purposes. This (innovative) source term constitutes the matter of the present paper; after a necessary reminder about the CFD / CAA hybrid approach and coupling techniques, a brief state-of-the-art of the ‘source term’ question will be made. After what the specific source term this paper is about will be detailed, the “volumic coupling” it allows being then illustrated / early validated with two academic test cases applications.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p137.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p6" class="affilation"></a>3D Numerical Simulations of Acoustic Installation Effects on Aft Fan Noise for Turbofan Engine</h2>
<h3>Stéphane Redonnet, Guillaume Desquesnes, Eric Manoha</h3>
<p class="affilation">CFD and Aeroacoustics Departement, ONERA (French Aerospace Center), Bp 72, 29 av. de la Division Leclerc, 92322 - Châtillon, France</p>
<p><b>ABSTRACT</b><br>
This paper deals with the numerical study of installation effects, a subject which is relevant of the more general purpose of the aircrafts noise prevision and reduction. As an example of installation effects, we study here the potential shielding effect that an empennage airfoil could offer to the reduction of the aft fan noise produced by a coaxial engine. Because the numerical simulations constitute an as powerful as cheap tool of investigation, we use for it a solver developed at ONERA, the sAbrinA CFD/CAA platform. In particular, we take benefits from an innovative overlapping method recently implemented in it - a method which allows handling more easily the solid obstacles to be considered. As an illustration of both the methodology and the tool, a full-3D aft fan noise propagation is then computed over an installed (over an airfoil) engine.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p6.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p430" class="affilation"></a>Frequency-Domain Prediction of Sound Propagation Through Axisymmetric Flow Ducts</h2>
<h3>X. D. Li (1), X. Y. Li (1), F. Thiele (2)</h3>
<p class="affilation">(1) School of Jet Propulsion, Beihang University (BUAA), Beijing 100083, P.R. China (2) Institute of Fluid Mechanics and Engineering Acoustics, Berlin University of Technology, D10623 Berlin, Germany</p>
<p><b>ABSTRACT</b><br>
A frequency-domain computational aeroacoustics approach is developed for the prediction of azimuthal sound modes propagation in axisymmetric flow ducts. Different pseudo-time marching methods are implemented and compared including the upwind, four-stage Runge-Kutta, dual-time schemes. Numerical validations for hard walled ducts including simple and complex geometries are presented to evaluate the accuracy and efficiency of the proposed methods. It is shown all the implemented time marching methods can achieve converged numerical solutions. Comparatively, the four-stage Runge-Kutta scheme is most efficient while the upwind scheme is most time consumption. The local time stepping technique can accelerate numerical computation to some extent. The dual-time scheme has the advantage to improve numerical accuracy and expand numerical stability range.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p430.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p122" class="affilation"></a>Large Eddy Simulation of Jet Noise</h2>
<h3>X. Wu, G. J. Page, J. K. Luff, J. J. McGuirk, W. A. McMullan</h3>
<p class="affilation">Dept. of Aero. and Auto. Engineering, Loughborough University, Loughborough, Leicestershire LE11 3TU, UK</p>
<p><b>ABSTRACT</b><br>
Methods for the accurate prediction of far-field jet noise emitted by aeroengines have been under development for some time. To achieve this, one essential requirement is capture of the turbulence dominated noise sources in the jet shear layers and, for the low frequency contribution to noise, simulation of the dynamically active large eddies at the end of the jet potential core and just downstream. The method described in the present paper follows a hybrid approach, whereby an LES technique is first used to predict the unsteady characteristics of the turbulent noise sources in jet shear flows. This is then coupled to an integral method for acoustic propagation (Kirchhoff method). The nozzle geometry is included in the calculation domain and a fine mesh (~15 million cells) is used to improve resolution of the initial jet shear layer. The method is applied to a high Reynolds number (Re = 10<sup>6</sup>) cold turbulent round jet issuing into stagnant surroundings. Experimental data for mean and turbulent velocity components are used to assess the accuracy of the LES predictions. The directivity pattern of the predicted far-field noise is used to assess the performance of the hybrid method and to indicate the benefit, particularly for sideline noise, of inclusion of the nozzle in the calculation.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p122.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p186" class="affilation"></a>Experimental Study of the Aircraft Engine Duct Combined Liners</h2>
<h3>Yuri Khaletskiy (1), Vjacheslav Povarkov (1), Rollan Shipov (1), Galina Shul’ (2)</h3>
<p class="affilation">(1) Central Institute of Aviation Motors after Baranov, Aviamotornaya str., 111116, Moscow, Russia (2) ORPE “Technologiya”, 15 Kievsky Road, 249035, Obninsk, Russia</p>
<p><b>ABSTRACT</b><br>
Experience of civil aircraft noise reduction up to requirements ICAO Annex 16 Chapter 4 has shown that the most effective engine noise reduction method is fan ducts treatment with broadband liners. So far single layer honeycomb liners are applied on a lot of engines. To increase liner width frequency band are applied two layer honeycomb liners. For this purpose flat models of the two-layer combined liners have been tested with the double reverberant chamber. The tested liners design differed from conventional two layer honeycomb liner with the internal layer. The porous homogeneous layer was used instead of a honeycomb one. This material consists of silica fibers of average diameter 9 μm. It has porosity not less than 90%. The maximal temperature of operation of this fibrous material makes up 1100°C, the density can vary from 150 up to 400 kg / m<sup>3</sup>. It was shown that acoustic efficiency of the two-layer combined liner is close to the two layer honeycomb liner of equal thickness. Owing to high acoustic efficiency of the porous layer on the wide frequency band the combined liner loses resonant properties of the acoustic response. In this case external to the duct flow the honeycomb layer for the porous layer can play a role of protection from influence high-speed turbulent flow. Thus combined two-layer liners can appear preferable at cost, weight, and operational adaptability to manufacture in comparison with conventional two layer honeycomb liners.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p186.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p519" class="affilation"></a>Time-Domain Acoustic Simulation of 3D Lined Ducts with Flow Using an Unstructured Discontinuous Galerkin Method</h2>
<h3>Yves Reymen, Martine Baelmans, Wim Desmet</h3>
<p class="affilation">Department of Mechanical Engineering, Katholieke Universiteit Leuven, Belgium</p>
<p><b>ABSTRACT</b><br>
Recently the authors proposed a new formulation to impose time-domain impedance boundary conditions. In a first step, the impedance values in the frequency-domain are fitted onto template functions. In a second step, the pressure in the time-domain can be calculated analytically as the convolution of the impedance fit of the first step with the velocity, approximated as a constant or linear function. The resulting formulation can be written in a recursive form which makes it very efficient. It requires only some additions and multiplications; the storage is limited to one value per template in the fit. The impedance model can be garanteed to be causal, real and passive; and is particularly suited for broadband simulations.-The formulation is implemented within the framework of an unstructured Quadrature--Free Discontinuous Galerkin Method for solving the Linearized Euler Equations. The validity-of the approach has been demonstrated before for the NASA Langley Flow Impedance Tube-benchmark for characterisation of lining material in a square duct without and with grazing-mean flow at several frequencies. In this paper, the formulation is further validated on a more-realistic case of a turbofan nacelle geometry.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p519.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p390" class="affilation"></a>Aural Characteristic of the Bone Conduction Speaker on the Cheek Bone</h2>
<h3>Kenji Muto (1), Kunihiko Takano (1), Guoyue Chen (2), Kikuo Asai (3), Kimio Kondo (3)</h3>
<p class="affilation">(1) Tokyo Metropolitan College of Industrial Technology, 8-17-1 Minamisenju, Arakawa-ku, Tokyo, 116-8523, Japan (2) Department of Electronics and Information Systems, Akita Prefectual University, 84-4 Ebinokuchi, Tsuchiya, Honjo city, Akita, 015-0055, Japan (3) National Institute of Multimedia and Education, 2-12 Wakaba, Mihama, Chiba, 261-0014, Japan</p>
<p><b>ABSTRACT</b><br>
Recently, various products using bone conduction speakers have been developed. When such products are used, bone conduction speakers are placed on the cheekbone. This gives the advantage of hearing the bone conduction sound while using an ear protector in a noise environment. It also gives the advantage of hearing the sound of air conduction and bone conduction at the same time. Aural characteristics of the bone conduction speaker on the cheek bone were measured. Specifically, this study investigated the equivalent sound of the air conduction to the bone conduction sound. It was shown that the relation between the vibration of the bone conduction and the sound pressure of air conduction is linear. In addition, a listening test of Japanese words was conducted. It was shown that the subjects had clearly recognized them.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p390.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p359" class="affilation"></a>Binaural Directivity Pattern Measurements and Simulation of the KEMAR Head Model</h2>
<h3>Soon Suck Jarng</h3>
<p class="affilation">Dept. of Information & Communication Eng. Chosun University, Gwang-Ju 501-759, South Korea</p>
<p><b>ABSTRACT</b><br>
Two twin microphones may produce particular patterns of binaural directivity by time delays between the twin microphones. The boundary element method (BEM) was used for the simulation of the sound pressure field around the KEMAR head model in order to quantify the acoustic head effect. The sound pressure onto the microphone was calculated by the BEM to an incident sound pressure. Then a planar directivity pattern was formed by four sound pressure signals from four microphones. The optimal binaural directivity pattern may be achieved by adjusting time delays at each frequency while maintaining the forward beam pattern is relatively bigger than the backward beam pattern. The simulation results were verified by the experimental measurement.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p359.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p360" class="affilation"></a>Digital Hearing Aid DSP Chip Parameter Fitting Optimization</h2>
<h3>Soon Suck Jarng</h3>
<p class="affilation">Dept. of Information & Communication Eng. Chosun University, Gwang-Ju 501-759, South Korea</p>
<p><b>ABSTRACT</b><br>
DSP chip parameters of a digital hearing aid (HA) should be optimally selected or fitted for hearing impaired persons. The more precise parameter fitting guarantees the better compensation of the hearing loss (HL). Digital HAs adopt DSP chips for more precise fitting of various HL threshold curve patterns. A specific DSP chip such as Gennum GB3211 was designed and manufactured in order to match up to about 4.7 billion different possible HL cases with combination of 7 limited parameters. This paper deals with a digital HA fitting program which is developed for optimal fitting of GB3211 DSP chip parameters. The fitting program has completed features from audiogram input to DSP chip interface. The compensation effects of the microphone and the receiver are also included. The paper shows some application examples.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p360.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p607" class="affilation"></a>Assessment of the Smoothness of Surfaces with an Acoustical Probe</h2>
<h3>A. Le Bot , H. Zahouani , R. Vargiolu (1), A. Mavon (2)</h3>
<p class="affilation">(1) Laboratoire de tribologie et dynamique des systemes, UMR 5513 CNRS, Ecole centrale de Lyon, 36, av. Guy de Collongue 69134 Ecully, France (2) Institut de recherche Pierre-Favre, 31322 Castanet Tolosan, France</p>
<p><b>ABSTRACT</b><br>
The feeling of smoothness during the touching is delivered when the finger is rubbed on the surface. A static contact cannot provide such an information. The roughness noise, that is the friction noise generated during the sliding of two rough surfaces, is therefore the key phenomenon for the feeling of smoothness. To this end, a tribo- acoustical probe has been designed. This is a sort of artificial finger whose load is controlled and equipped with a microphone to measure the Sound Pressure Level. When rubbing the probe on various surfaces, it is possible to compare the acoustical level and therefore to assess the relative smoothness of the surfaces. Among them, some results are presented on skins with different ages, on different parts of the body, on skins before and after cleaning by acetone. Finally, this method is applied to assess the efficiency of cosmetics.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p607.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p304" class="affilation"></a>Promotion of Extraction of Green Tea Catechins in Water Extraction at Low Temperature Using Ultrasound</h2>
<h3>Hitoshi Koiwai, Nobuyoshi Masuzawa</h3>
<p class="affilation">Musashi Institute of Technology, 1-28-1 Tamazutsumi, Setagaya-ku, Tokyo 158-8557, Japan</p>
<p><b>ABSTRACT</b><br>
Attention has been paid to the pharmacological actions of natural elements since hazardous properties of artificial synthetic things contained in foods and medicines have come to be indicated. Lots of catechins, polyphenols, are contained in green tea. It is known that the catechins have many actions such as antioxidation and antibacteria. Effective use of catechins in green tea is expected. For extracting the green tea catechins, the hot water extraction method and the organic solvents method are used. Although the hot water extraction is safe, the heat causes changes in quality and loss of catechins. Extraction at low temperatures is desirable to avoid these changes, while efficiency of the extraction is low. Authors have made studies to raise the efficiency by using ultrasound and have found that ultrasonic irradiation is effective. In this study, the effect of ultrasonic frequency on the promotion of extraction was mainly examined. Ultrasonic frequencies used were 25, 45, 100 and 130 kHz. Catechins extracted versus irradiation time were measured. It was found that the extraction was promoted by ultrasonic irradiation in all frequencies. The degree of promotion increased with frequency in the examined frequencies.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p304.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p39" class="affilation"></a>Use of Scattering of Ultrasound Pulses and Shock Waves by Kidney Stones for Imaging in Lithotripsy</h2>
<h3>Oleg A. Sapozhnikov (1,2), Neil R. Owen (2), Michael R. Bailey (2), Alexander I. Gromov (3), Lawrence A. Crum (2)</h3>
<p class="affilation">(1) Department of Acoustics, Physics Faculty, Moscow State University, Leninskie Gory, Moscow 119992, Russia (2) Center for Industrial and Medical Ultrasound, Applied Physics Laboratory, University of Washington, 1013 NE 40th Street, Seattle WA 98105, USA (3) Mandryka 2nd Central Clinical Military Hospital, 8A Bolshaya Olenya Street, Moscow 107014, Russia</p>
<p><b>ABSTRACT</b><br>
Shock wave lithotripsy, as a procedure for kidney stones fragmentation, would be more efficient if the kidney stone position and size are estimated, and if the progress of the stone fragmentation by shock waves is assessed. These two challenges can be addressed using scattering of ultrasound waves on stones. Although the acoustic impedance of stones often differs by more than a factor of 2 from surrounding tissue, stones are not always readily visible on B-mode ultrasound, for example because a small stone can be lost in the speckle of the kidney tissue. However, we and others have found stones can be made to light up on Doppler imaging in what is called a “twinkling artifact”, that may be in part due to stone displacement by acoustic radiation force and partly due to multiple scattering at rough edges. As for fragmentation feedback, fractures in the stone push the frequency of resonance scattering of lithotripter shock wave to bands related to the reverberation period of the pieces. Acoustic scattering of the diagnostic pulses and shock waves by the stones was calculated numerically using a linear elastic model, initialized with known elastic constants. Based on this data, acoustic radiation force and scattered field in the farfield were calculated using integral representation of the corresponding parameters. These methods provide new ways to locate kidney stone stones and to monitor the fragmentation process.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p39.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p623" class="affilation"></a>How Termites Use Vibration to Assess Potential Food Structures</h2>
<h3>Ra Inta (1,2), Joseph C.S. Lai (1), Theo A. Evans (2)</h3>
<p class="affilation">(1) School of Aerospace, Civil and Mechanical Engineering, The University of New South Wales at the Australian Defence Force Academy, Canberra, ACT 2600, Australia (2) CSIRO Entomology, Clunies Ross st, Canberra, ACT 2600, Australia</p>
<p><b>ABSTRACT</b><br>
It has been long known that termites use vibration as a communication channel in a variety of ways. For example alarm signals produced by the soldiers, clearly audible to the unaided ear, elicit a programmed defensive response in the workers. It appears that they are also receptive to vibration through the substrate they inhabit and are able to use this information to some extent. Our recent work has shown that they are able to use information gained through structural vibration, not only to assess the volume, but also to determine a difference in material properties of the potential food source. This degree of sophistication in their vibratory assessment methods has not been shown before. This work raises questions as to the key vibratory property they use in managing their foraging preferences and suggests that they make use of features other than only the fundamental frequency of the food source, or its total mass.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p623.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p425" class="affilation"></a>Monitoring and Assessment of Aircraft Noise in an Airport’s Neighborhood</h2>
<h3>M. K. Law (1), K. M. Li (2)</h3>
<p class="affilation">(1) Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hung Hom, Hong Kong (2) Ray W. Herrick Laboratories, School of Mechanical Engineering, Purdue University, IN 47907-2031, USA</p>
<p><b>ABSTRACT</b><br>
Airports have grown continually worldwide and nearly unabated since the mid-1960s. This persistent growth has frequently been accompanied by a negative community reaction and created turmoil between airports, municipalities, and the surrounding communities. In recent years, there has been a significant increase in air traffic internationally. Airports are constantly seeking to expand their capacity. In the quest for expansion of services, it becomes vitally important for airports and communities to collaborate with mutual benefits in mind, especially regarding land use. This research examines land-use decisions and their relation to airport noise concerns and complaints. In an effort to gain a better perspective of the actual noise exposure of individuals who frequently complain about aircraft noise, noise data in these neighborhoods were recorded and analyzed. Access was granted within the homes of two frequent complainants and one non-complainant. A continuous set of 24-hour noise data was recorded both inside and outside each of these homes. A series of noise data samples was also taken simultaneously at various locations through affected neighborhoods over several days. This noise data will provide a better understanding of the actual noise experienced in the locations of the affected communities and provide a baseline comparison to future noise data samples and noise complaint patterns.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p425.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p712" class="affilation"></a>Correlation of Rural Highway Road Traffic Noise with Vehicle Speed and Commercial Vehicle Percentages for the Day and Night Time Periods</h2>
<h3>Matthew Stead (1), Darren Jurevicius (1), Philip Agnew (2)</h3>
<p class="affilation">(1) Bassett Acoustics, Level 6, 100 Pirie Street, Adelaide, SA 5000, Australia (2) Department Transport, Energy and Infrastructure, 33-37 Warwick Street, Walkerville, SA 5081, Australia</p>
<p><b>ABSTRACT</b><br>
Road traffic noise and associated noise model predictions for rural highways are heavily influenced by the speed and number of commercial vehicles. It is in the public’s interest to improve the accuracy of noise models to enable accurate representation of traffic noise impacts and design of appropriate noise mitigation treatment. A study has been carried out to measure road traffic noise simultaneously with traffic counts using commercially available noise and traffic count loggers. The correlation between traffic noise, vehicle type, variations between day and night and the effects of speed have been assessed at a rural location in South Australia. The correlations are presented for the purpose of gaining a better understanding of vehicle class noise emission values with respect to recognised noise models prediction for rural highways.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p712.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p605" class="affilation"></a>Protection against Noise on A6 Highway Rijeka-Zagreb, Karlovac-Novigrad Section</h2>
<h3>Vesna Dragcevic (1), Ivica Stanceric (1), Marko Vajdic (2)</h3>
<p class="affilation">(1) University of Zagreb, Faculty of Civil Engineering, Kaciceva 26, 10000 Zagreb, Croatia (2) Civil Engineering Institute of Croatia, Rakusina 1, 10000 Zagreb, Croatia</p>
<p><b>ABSTRACT</b><br>
Although it is not a member of European Union, The Republic of Croatia has brought the regulation regarding the noise protection which has been harmonized with The European Directive 2002/49/EC. Technical committee within the Croatian Normization Institute has acquired more than a hundred European norms from this area. In spite of that the noise protection in urban regions of Croatia is carried out sporadically. Only in those areas along roads where the noise levels are extremely high and the objections of local residents directed to town authorities are frequently repeated for years. The situation is completely different in case of excessive noise levels of the inhabited areas along highways. Stock companies which manage highways follow the orientation of the Republic of Croatia to take special care of the environment, and, thus, of the noise protection. Approximately 10 years ago intensive road construction started in Croatia and so far 1062 kilometres of highways have been built. The solutions for the noise protection that have been planned in the project documentation, mostly walls, have been carried out. In this paper the procedure of predicting the noise level in the environment in the process of making project documentation has been described for the section of the highway Karlovac-Novigrad. The real situation in the environment regarding the noise caused by traffic was determined by field measurements five years after the section in question had been opened to traffic. The prediction of noise protection on the project level has been commented upon with regard to the present noise condition when the highway is in circulation. It has been pointed out that that the noise protection by walls is only one very important, but not sufficient measure, and that overall solution requires permanent monitoring, establishing the system of condition monitoring, analysis of effectiveness and the possibility of application of other primary and secondary protection measures.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p605.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p475" class="affilation"></a>Investigation of Quantum and Classical Models for Molecular Relaxation Using the Direct Simulation Monte Carlo Method</h2>
<h3>Amanda D. Hanford (1), Patrick D. O’Connor (2), Lyle N. Long (3), James B. Anderson (2)</h3>
<p class="affilation">(1) Graduate Program in Acoustics, The Pennsylvania State University, University Park, PA 16802, USA (2) Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA (3) Department of Aerospace Engineering, The Pennsylvania State University, University Park, PA 16802, USA</p>
<p><b>ABSTRACT</b><br>
It is widely known that losses due to viscous, thermal and molecular relaxation play an important role in sound propagation. Traditionally, acoustics is concerned with the treatment of the fluid as a (linear) continuum using macroscopic quantities such as velocity and pressure as dependent variables. However, the continuum model has its limitations and the model breaks down for Knudsen numbers (Kn) greater than roughly 0.05, where Kn is defined as the ratio of mean free path to wavelength. Particle or Boltzmann equation methods are necessary for, but not limited to, problems with Kn > 0.05. In our studies we have used a particle method, Bird;s direct simulation Monte Carlo method, to study acoustics which allows us to simulate real gas effects for all values of Kn with a molecular model that continuum methods cannot offer. Direct simulation Monte Carlo allows us to explore acoustics at varying temperatures, molecular composition, Knudsen numbers, and amplitude. Our current simulations of gas mixtures have employed different methods to model the internal degrees of freedom in molecules and the exchange of translational, rotational and vibrational energies in collisions. One of these methods is the fully classical rigid-rotor/harmonic-oscillator model for rotation and vibration developed by Borgnakke and Larsen. A second takes into account the discrete quantum energy levels for vibration with rotation treated classically. This method gives a more realistic representation of the internal structure of diatomic and polyatomic molecules. In our studies, we have investigated the application of these methods with the direct simulation - at the molecular level - of the propagation of sound and its attenuation along with their dependence on temperature for diatomic nitrogen systems.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p475.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p696" class="affilation"></a>Split Region Acoustical Wave Propagator and its Applications</h2>
<h3>Bradley McGrath, Hongmei Sun, Jingbo Wang, Jie Pan</h3>
<p class="affilation">School of Mechanical Engineering, The University of Western Australia, Perth, WA6009, Australia</p>
<p><b>ABSTRACT</b><br>
In this paper, we present a recently developed split region method that solves the timedependent acoustic wave equation with greatly increased efficiency. This method uses a Chebyshev propagation scheme in areas where there are interfaces and medium variations, and a simple free space propagator where the medium is homogenous. It is proven to be highly accurate and effective. It can easily incorporate variations and boundaries in the propagation medium to simulate a “real-life” wave passing through air, liquids, and solids.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p696.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p280" class="affilation"></a>An Analysis of the Changes to the Mechanical and Acoustical Properties of Paper Caused by the Damage Mechanisms Present in the Fibre Structure</h2>
<h3>David Kao, Deryn Graham, Koulis Pericleous</h3>
<p class="affilation">School of Computing and Mathematical Sciences, University of Greenwich, Park Row, Greenwich, London, SE10 9LS, UK</p>
<p><b>ABSTRACT</b><br>
This paper will analyse two of the likely damage mechanisms present in a paper fibre matrix when placed under controlled stress conditions: fibre/fibre bond failure and fibre failure. The failure process associated with each damage mechanism will be presented in detail focusing on the change in mechanical and acoustic properties of the surrounding fibre structure before and after failure. To represent this complex process mathematically, geometrically simple fibre arrangements will be chosen based on certain assumptions regarding the structure and strength of paper, to model the damage mechanisms. The fibre structures are then formulated in terms of a hybrid vibro-acoustic model based on a coupled mass/spring system and the pressure wave equation. The model will be presented in detail in the paper. The simulation of the simple fibre structures serves two purposes; it highlights the physical and acoustic difference of each damage mechanism before and after failure, and also shows the differences in the two damage mechanisms when compared with one another. The results of the simulations are given in the form of pressure wave contours, timefrequency graphs and Continuous Wavelet Transform (CWT) diagrams. The analysis of the results leads to criteria by which the two damage mechanisms can be identified. Using these criteria it was possible to verify the results of the simulations against experimental acoustic data. The models developed in this study are of specific practical interest in the paper-making industry, where acoustic sensors may be used to monitor continuous paper production. The same techniques may be adopted more generally to correlate acoustic signals to damage mechanisms in other fibre-based structures.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p280.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p453" class="affilation"></a>Strong Coupling of the Fast Multilevel Multipole Boundary Element Method with the Finite Element Method for Vibroacoustic Problems</h2>
<h3>Dominik Brunner, Michael Junge, Lothar Gaul</h3>
<p class="affilation">Institute of Applied and Experimental Mechanics, University of Stuttgart, 70550 Stuttgart, Germany</p>
<p><b>ABSTRACT</b><br>
Nowadays, the sound quality has an ever-growing influence on the overall impression of a product. To predict the sound radiation of structures, both a structural and an acoustic problem have to be solved. In this work, the structural part is modelled by the finite element (FE) method, whereas the exterior acoustic problem is efficiently simulated with the boundary element (BE) method. To overcome the well known bottleneck of fully populated boundary element matrices, the fast multilevel multipole method is applied. In case of thin structures and dense fluids, a strong coupling between the two problems is essential, since the effect of the acoustic pressure onto the surface of the structure is not negligible. Two different methods are investigated: First, the structural displacements are eliminated yielding a Schur complement formulation. Secondly, the problem is formulated with a Lagrangian multiplier and an Uzawa-type algorithm with nested inner-outer iterations is applied. In both cases, iterative solvers with different preconditioners are used.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p453.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p361" class="affilation"></a>The Head Related Transfer Function Simulation by FEM/IEM and Reciprocal Theorem</h2>
<h3>Hiroshi Muraoka (1), Yuta Takahashi (1), Tubagus Haedar (1), Makoto Otani (2), Tatsuya Hirahara (2)</h3>
<p class="affilation">(1) Research Center of Computational Mechanics, Inc., Togoshi NI-Bldg. 1-7-1 Togoshi, Shinagawa-ku, Tokyo, 142-0041, Japan (2) Department of Intelligent Systems Design Engineering, Toyama Prefectural University, Imizu City, Toyama, 939-0398, Japan</p>
<p><b>ABSTRACT</b><br>
An effective method of reducing computational cost involving Head Related Transfer Function (HRTF) simulation for high frequency is to apply the reciprocal theorem. Commonly, the Boundary Element Method is used since both calculation and mesh generation effort are minimal, however it is sensitive to geometry complexity and unstable during the discretization of the reciprocal theorem. Hence, in order to eliminate the errors and increase the efficiency of the outcome, this report demonstrates a new approach to Head Related Transfer Function (HRTF) simulations by coupling Finite Element Method (FEM) with Infinite Element Method (IEM). First, the validity of the reciprocal theorem was examined by comparing numerical results along with the impulse response up to 1000Hz. Once the accuracy has been established, further studies were carried out between 10 and 20 kHz to illustrate the practicability of this method.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p361.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p598" class="affilation"></a>Study on Acoustic Scattering by Hard Plane and Soft Surface Multi-Cracked Plate</h2>
<h3>Jiang Lin, Zhao De-You</h3>
<p class="affilation">Department of Naval Architecture, Dalian University of Technology, LiaoNing, DaLian116024, China</p>
<p><b>ABSTRACT</b><br>
The acoustic scattering characteristics of finite plates with multi-cracks and different surface conditions are studied .The boundary element method is used to evaluate the exterior acoustic field. Numerical examples show that the cracks have an influence on scattering acoustic pressure in that the sound pressure decrease as the cracks increase. Both hard plane and soft surface with cracks can be examined by the diversification of sound pressure and directivity of pattern. Further research of acoustic scattering by damage structure is discussed.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p598.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p83" class="affilation"></a>Partition Hole Design for Maximizing or Minimizing the Fundamental Eigenfrequency of a Double Cavity by Topology Optimization</h2>
<h3>Jin Woo Lee, Yoon Young Kim</h3>
<p class="affilation">National Creative Research Initiatives Center for Multiscale Design, School of Mechanical and Aerospace Engineering, Seoul National University, San 56-1 Shilim-9-dong, Kwanak-gu, Seoul, 151-742, Republic of Korea</p>
<p><b>ABSTRACT</b><br>
A topology optimization method is developed to minimize or maximize the fundamental eigenfrequency of a double cavity. The acoustic model consists of two rectangular cavities and a holey partition. Because the number and locations of holes in the partition affect the eigenfrequencies of the double cavity significantly, the underlying acoustical characteristics of the double cavity can be controlled by adjusting them. In this work, the eigenfrequency control problem is formulated as an acoustical topology optimization problem where the fundamental acoustic eigenfrequency is minimized or maximized for an allowed hole volume. For the formulation, the partition is divided into sub-partitions, each of which has variable material properties. When a sub-partition has acoustical properties of air, it is regarded as a hole. Intermediate states between air and a rigid body are interpolated by a carefully-selected penalized function in order to produce a clear hole distribution at the converged iteration.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p83.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p452" class="affilation"></a>Comparison of Higher-Order Numerical Schemes and Several Filtering Methods Applied to Navier-Stokes Equations with Applications to Computational Acoustics</h2>
<h3>Liang S. Lai, Georgi S. Djambazov, Choi-Hong. Lai, Koulis A. Pericleous</h3>
<p class="affilation">School of Computing and Mathematical Sciences, University of Greenwich, Old Royal Naval College, Park Row, London SE10 9LS, U.K.</p>
<p><b>ABSTRACT</b><br>
In computational acoustics, fluid-acoustic coupling methods for the computation of sound have been widely used by researchers for the last five decades. In the first part of the coupling procedure, the fully unsteady incompressible or compressible flow equations for the near-field of the unsteady flow are solved by using a Computational Fluid Dynamics (CFD) technique, i.e., Direct Numerical Simulation (DNS), Large Eddy Simulation (LES) or unsteady Reynolds averaged Navier-Stokes equations (RANS); results of these simulations are then used to calculate sound sources using the acoustic analogy or by solving a set of acoustic perturbation equations (APE) leading to the solution of the acoustic field. It is possible to use a 2-D reduced problem to provide preliminary understanding of many acoustic problems. Unfortunately 2-D CFD simulations using a fine-mesh-small-time-step-LES-alike numerical method cannot be considered as LES which applies to 3-D simulations only. Therefore it is necessary to understand the similarities and the effect between filters applied to unsteady compressible Navier-Stokes equations and the combined effect of high-order schemes and mesh sizes. The aim of this study is to provide suitable LES-alike methods for 2-D simulations. An efficient software implementation of high order schemes is also proposed. Numerical examples are provided to illustrate these empirical similarities.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p452.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p287" class="affilation"></a>An Acoustic Finite Element Including Viscothermal Effects</h2>
<h3>M. J. J. Nijhof, Y. H. Wijnant, A. de Boer</h3>
<p class="affilation">Chair of Structural Dynamics and Acoustics, University of Twente, P.O. box 217, 7500AE Enschede, The Netherlands</p>
<p><b>ABSTRACT</b><br>
In acoustics it is generally assumed that viscous- en thermal boundary layer effects play a minor role in the propagation of sound waves. Hence, these effects are neglected in the basic set of equations describing the sound field. However, for geometries that include small confinements of air or thin air layers, this assumption is not valid. Special models that include viscous and thermal effects are available (for example the Low Reduced Frequency model) but only for a limited number of geometries. To overcome these limitations and provide a solution that can be used for arbitrary geometries, an acoustic finite (2D) element that includes viscous and thermal effects is developed. The model is based on the linearized Navier stokes equations (including shear), the equation of continuity, the equation of state for an ideal gas and the energy equation. The method of weighed residuals is used in combination with a mixed formulation of pressure, temperature and particle velocity degrees of freedom. The results of the developed element code are compared with the results of an existing (analytical) Low Reduced Frequency solution and a viscothermal element that was found in literature.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p287.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p125" class="affilation"></a>Boundary Element Models of Horn Loaded Loudspeakers</h2>
<h3>Rick C. Morgans (1), Anthony C. Zander (1), Colin H. Hansen (1), David J. Murphy (2)</h3>
<p class="affilation">(1) School of Mechanical Engineering, University of Adelaide, Adelaide, SA 5005, Australia (2) Krix Loudspeakers Pty Ltd, Hackham, SA 5163, Australia</p>
<p><b>ABSTRACT</b><br>
Horn loaded loudspeakers are a type of loudspeaker used to efficiently radiate sound in a directional manner. Traditional horn theory takes a lumped parameter approach and these models are found to be inadequate at mid to high frequencies, as well as only being able to predict the sound pressure on axis. No directional information is provided with these models, and alternative approaches such as finite or boundary element methods are sought to overcome these limitations. This paper compares results obtained using two alternative boundary element based techniques, a traditional direct boundary element method and a new source superposition technique. Two representative horn loaded loudspeakers are modelled, and the results are compared to experiment.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p125.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p126" class="affilation"></a>Derivative Free Optimisation in Engineering Acoustics</h2>
<h3>Rick C. Morgans (1), Carl Q. Howard (1), Anthony C. Zander (1), Colin H. Hansen (1), David J. Murphy (2)</h3>
<p class="affilation">(1) School of Mechanical Engineering, University of Adelaide, SA, Australia 5005 (2) Krix Loudspeakers, Hackham, SA, Australia 5163</p>
<p><b>ABSTRACT</b><br>
This paper describes recent work on the optimisation of very complex or computationally expensive systems such as those found in many engineering acoustics applications. It uses optimisation techniques that require no knowledge of the derivative of the objective function with respect to the input variables, and hence is suitable for application to problems where the derivative is potentially noisy or expensive to calculate by a finite difference approximation, difficult to calculate analytically, or simply unavailable as is the case in many commercial codes. The paper begins with a brief review of optimisation methods as applied to acoustic problems, and discusses the limitations of traditional techniques. The theory of two derivative free optimisation methods, a parallel genetic algorithm and a surrogate optimisation technique called Efficient Global Optimisation (EGO) are then described. Two example cases are then discussed: the optimisation of the position and design parameters of vibroacoustic absorbers mounted on the interior of a rocket payload bay to reduce the payload interior pressure fluctuations on launch; and the shape optimisation of an audio loudspeaker to improve sound quality. Finally future directions and challenges in this field are discussed.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p126.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p30" class="affilation"></a>A Numerical Study of Sound-Structure Interaction in a Duct Structure by the Acoustical Wave Propagator Method</h2>
<h3>Shuzhi Peng, Li Cheng</h3>
<p class="affilation">Department of Mechanical Engineering, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong</p>
<p><b>ABSTRACT</b><br>
The pseudospectral time-domain method has long been used to describe the acoustical wave propagation. However, due to the limitation and difficulties of the FFT, the dispersion error is hard to be avoided and the computational accuracy greatly decreases after the waves arrive at the non-periodic boundary. To resolve this problem, the Lagrange-Chebyshev interpolation polynomials are used to replace the previous FFT. In addition, a mapping method is introduced to overcome the additional time-step restriction. In this paper, several issues are addressed to explore its numerical performances: the numerical accuracy, computational efficiency and stability of this proposed method.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p30.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p480" class="affilation"></a>Graft of the Boundary Integral Method Onto the Image-Source Method for Vehicle Acoustics</h2>
<h3>Vincent Martin (1), Thomas Guignard (2)</h3>
<p class="affilation">(1) Institut Jean Le Rond d’Alembert, CNRS/Paris VI 2, Place de La Gare de Ceinture, F-78210 St Cyr l’Ecole, France (2) EPFL - Ecole Polytechnique Fédérale de Lausanne, LEMA - Laboratoire d’Electromagnétisme et d’Acoustique, Station 11, CH-1015 Lausanne, Switzerland</p>
<p><b>ABSTRACT</b><br>
The solution obtained with the acoustical image sources method was shown to be the contribution of terms issued from a series development of the integral method (believed to be the exact solution).Missing terms in the geometrical method represent, among others, the contribution of diffraction. Taking all of them into account would indeed lead back to the full integral method. Alternatively, would it be possible to consider only a subset of these terms, therefore adding missing information to the geometrical method? This would bring the latter to its much-awaited role in the medium-frequency range.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p480.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p435" class="affilation"></a>Benchmark Tests to Rank Software for Noise Prediction</h2>
<h3>Wolfgang Probst</h3>
<p class="affilation">ACCON GmbH and DataKustik GmbH, D-86926 Greifenberg, Germany</p>
<p><b>ABSTRACT</b><br>
Software for Noise Prediction is an invaluable tool to analyze complex situations. From detailed noise studies in industrial plants including calculations up to high reflection orders to large scale noise maps for hundreds of km<sup>2</sup> completely different subjects are covered by these software packages. Unfortunately it is quite difficult for potential users like consultants and administrations to decide about pros and cons of different products. User friendliness, speed of calculation and transparency are important properties beside the mainly published list of features. Methods based on the German standard DIN 45687 as well as more detailed test cases are presented to reveal these properties and to help decision makers to find a product best for their needs.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p435.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p3" class="affilation"></a>Energy Consumption and Machinery Vibrations</h2>
<h3>A. Elkhatib</h3>
<p class="affilation">Production Engineering Department, Faculty of Engineering, Alexandria University, Egypt</p>
<p><b>ABSTRACT</b><br>
The main objective of this paper is to establish a methodology to obtain relationships between machinery vibration levels and their power consumption, for different machine faults. A survey of literature for this subject has shown that, in spite of the growing concerns about the effect of vibration levels on the power consumption, yet very little research has been done in this area. The paper treats this subject in a very broad manner, taking into consideration not only the effect of vibration levels on the power consumption, but also the effect of the frequencies at which these levels occur. A good application for this phenomenon was taken as the machinery condition monitoring and fault diagnosis through vibration measurements and analyses. Mobility measurements and Frequency Response Functions (FRF’s) for the machines using impact testing were taken into consideration for the calculation of lost energy due to vibration. These were compared to actually measured energy losses. From this comparison a rationale methodology for predicting energy losses for vibrating machinery is suggested.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p3.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p715" class="affilation"></a>Gearbox Fault Detection by Motor Current Signature Analysis</h2>
<h3>A. R. Mohanty</h3>
<p class="affilation">Department of Mechanical Engineering, Indian Institute of Technology Kharagpur, Kharagpur, 721 302, India</p>
<p><b>ABSTRACT</b><br>
In this paper the results of an experimental study on fault detection in a gearbox using motor current signature analysis is presented. Broken teeth and teeth wear have been artificially introduced in the gears as faults. Signal processing techniques like the multiresolution fourier transform (MFT) has been used for feature extraction from the current signals drawn by the induction motor driving the gear box. The present technique is able to detect faults at very low loads on the gearbox, where the modulation index is very low. Such a technique can be used to successfully detect faults in many rotating machines.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p715.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p208" class="affilation"></a>Spectral Analysis of Tapered Roller Bearing Vibration Using Inductive Modeling</h2>
<h3>Adam Docekal, Marcel Kreidl, Radislav Smid, Lubomir Riha</h3>
<p class="affilation">Department of Measurement, Faculty of Electrical Engineering, Czech Technical University in Prague, 166 27 Prague 6, Czech Republic</p>
<p><b>ABSTRACT</b><br>
This paper deals with a case of vibroacoustic testing of tapered roller bearings. Tapered roller bearings are often used at the mechanical designs where higher requirements on rigidity and accuracy of a shaft roller placing are asserted. This is especially the case of metal cutting machine shafts or automotive gearboxes. Even a small clearance must be excluded in both mentioned designs and thus used tapered roller bearings are axially mechanically preloaded. The vibrations of the tapered roller bearings were measured at the tapered roller bearings stand which was designed for this purpose. The testing stand consisted of a shaft placing fitted with two tapered roller bearings. Influence of a bearing axial mechanical preload on the vibration level was evaluated. On the basis of that evaluation the optimal value of the axial mechanical preload forcing on a tapered roller bearing was estimated. The measured vibration was evaluated using methods of spectral analysis. The fact that bearing defects can be often detected and localized by their characteristic frequencies was taken into consideration. The axial preload should affect the levels of vibration at the bands where these frequencies occur. The bands were determined in two ways. Firstly, they were calculated from bearing dimensions and the shaft revolution rate. Secondly, they were estimated directly from the measured data using Inductive Modeling. Inductive modeling methods enable us to recognize those bands which are most affected by the preload and hence those bands might be important for the evaluation of the influence of the axial preload on the tapered roller bearing vibration level. In particular, the Group Method of Data Handling and the Group of Adaptive Models Evolution were used.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p208.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p266" class="affilation"></a>Vibration Event Detection: A Monitoring Method for Slow Speed Bearings</h2>
<h3>Craig Moodie (1), A. K. Tieu (1), Simon Biddle (2)</h3>
<p class="affilation">(1) School of Mechanical, Materials and Mechatronic Engineering, Faculty of Engineering, University of Wollongong, NSW, Australia (2) Senior Condition Monitoring Engineer, Bluescope Steel, Port Kembla, NSW, Australia</p>
<p><b>ABSTRACT</b><br>
Traditional signal analysis methods appear to fail in their ability to provide consistent meaningful information when presented with data from large slow moving slew bearings. A number of reasons for this are presented. Statistics obtained from vibration data collected from a large Coal Reclaimer and an experimental test-rig is discussed. The Coal Reclaimer rotates at 4.3 rpm about two vertically mounted, large, slew bearings. The experimental test-rig rotates at 1 rpm in the horizontal plane. These statistics are compared to the results obtained using a simple event detection algorithm. The event detection algorithm is detailed and its strengths discussed relative to other methods. It is found that the event detection method provides a consistent statistical view of the condition of the slew bearing but not necessarily better than simple statistical measures. The event detection algorithm is now being used as a condition monitoring tool on the test-rig designed to specifically condition monitor horizontally mounted slow speed (1 rpm) bearings to failure.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p266.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p265" class="affilation"></a>Symmetric Wave Decomposition as a Means of Identifying the Number of Damaged Elements in a Slow Speed Bearing</h2>
<h3>Craig Moodie (1), A. K. Tieu (1), Simon Biddle (2)</h3>
<p class="affilation">(1) School of Mechanical, Materials and Mechatronic Engineering, Faculty of Engineering, University of Wollongong, NSW, Australia (2) Senior Condition Monitoring Engineer, Bluescope Steel, Port Kembla, NSW, Australia</p>
<p><b>ABSTRACT</b><br>
This paper discusses a symmetry transformation (Symmetric Wave Decomposition - SWD) that identifies the ‘source’ forcing functions that are contained in a time-series. Knowledge of the number of active elements (principal components) in a roller bearing is crucial to identifying how many elements may be defective and or if external forcing functions are dominant. With an understanding of these ‘active components’ the vibration data is decomposed into each active component wave. From this it can be estimated how many active components are associated with an event or events, if the damage is local or likely to be external and the extent of the damage. Vibration data from a large industrial machine containing large (4.2 m diameter) slow speed (4 rpm) slew bearings has been processed with the SWD transform and the results are presented. The SWD algorithm is being implemented on an experimental test-rig that has been specifically built for the monitoring of slow speed (1 rpm) bearings.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p265.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p264" class="affilation"></a>De-Convolution of Time-Series Data Using Translational Symmetry and Eigenstate Analysis</h2>
<h3>Craig Moodie (1), A. K. Tieu (1), Simon Biddle (2)</h3>
<p class="affilation">(1) School of Mechanical, Materials and Mechatronic Engineering, Faculty of Engineering, University of Wollongong, NSW, Australia (2) Senior Condition Monitoring Engineer, Bluescope Steel, Port Kembla, NSW, Australia</p>
<p><b>ABSTRACT</b><br>
Translational Symmetry permits a time invariant matrix (a Ring Matrix) of a time series to be formed. Traditional Eigenvalue/vector and Fast Fourier Transform techniques applied to the Ring Matrix provide views of all the vibration modes, their magnitude and frequency content. The Ring Matrix has many interesting features associated with it that enable it to be used as an additional tool in defining the ‘condition state’ of a bearing. This paper introduces the Ring Matrix as a significant step in the ‘Blind’ deconvolution process. Application of the de-convolution method to vibration data obtained from both a large and small slow speed (1 to 4 rpm) slew bearing is presented. The Ring Matrix is being applied to the condition monitoring of a bearing which forms part of an experimental test rig specifically built to monitor slow speed (1 rpm) slew bearings with a view to predicting their remaining useful life. Results, from a Coal Reclaimer which has slow speed (4 rpm) slew bearings, are also presented to illustrate the various views of the vibration information.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p264.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p263" class="affilation"></a>Symmetry Methods Applied to the Condition-Monitoring of Slow Speed Slew Bearings</h2>
<h3>Craig Moodie (1), A. K. Tieu (1), Simon Biddle (2)</h3>
<p class="affilation">(1) School of Mechanical, Materials and Mechatronic Engineering, Faculty of Engineering, University of Wollongong, NSW, Australia (2) Senior Condition Monitoring Engineer, Bluescope Steel, Port Kembla, NSW, Australia</p>
<p><b>ABSTRACT</b><br>
All data has symmetry and anti-symmetry embedded in it. This paper discusses various aspects of symmetrical transformations that can be applied to data to give machine condition information. These transformations lead to novel views of the information. Combining these symmetrical transformations with the more traditional methods of Eigenvalue/vector and Fast Fourier Transform analyses provides views of the source and extent of the problem. To illustrate the various views of the vibration information, results from a large (4.2 m diameter) Coal Reclaimer slow speed (4 rpm) slew bearing are presented. Many of the transformations are also currently being evaluated on an experimental test-rig specifically designed for the monitoring of horizontal slow speed (1 to 4 rpm) slew bearings.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p263.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p771" class="affilation"></a>Impact Mass Estimation for a Plate Type Structure by Using Smoothed Wigner-Ville Distribution</h2>
<h3>Doo-Byung Yoon, Jin-Ho Park, Young-Chul Choi</h3>
<p class="affilation">Advanced Condition Monitoring & Diagnostics Lab., Korea Atomic Energy Research Institute, 1045 Daedeok-daero, Yuseong-gu, Daejeon, 305-353, Korea</p>
<p><b>ABSTRACT</b><br>
The LPMS (Loose Parts Monitoring System) is a monitoring system designed to detect, localize, and estimate the loose parts within the primary pressure boundary of a reactor system. When the LPMS gives an alarm signal, it is important to find out not only the impact location but also the mass of the loose part in order to make an accurate evaluation of the structural integrity of the reactor system. Conventionally, center frequency method and frequency ratio(FR) method have been widely used for a mass estimation. However, these methods do not work when the noise level becomes high. Thus a new method to more accurately estimate the impact mass is suggested. The validity of the proposed method is verified through an experiment. The experimental results demonstrate that the proposed method is valid for estimating the center frequency of an impact response signal easily even in a noisy environment. It is expected that the proposed method can be used to enhance the accuracy of the impact mass estimation for a plate type structure.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p771.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p716" class="affilation"></a>Using Vibrational Properties of the Wheel to Identify Tyre - Road Friction</h2>
<h3>Edwin de Vries (1), Daniel Rixen (1), Hiroyuki Katsuno (2), Thijs van Keulen (1,2)</h3>
<p class="affilation">(1) Delft University of Technology, Mekelweg 2, 2628 CD Delft, The Netherlands (2) Bridgestone Technical Centre Europe, Via del Fosso Del Salceto 13/15, 00129 Rome, Italy</p>
<p><b>ABSTRACT</b><br>
This paper describes the use of vibrations in a single passenger car wheel to identify road fiction. The peak in the transfer function of wheel speed to brake torque variations at the lowest resonance frequency (ca. 32 Hz) is strongly influenced by the ‘constraint’ provided by the road surface. A model of the wheel with its rotational inertia in contact with the road via the tyre is developed. The inflated tyre carcass provides the stiffness in all directions, here mainly the rotational motion of the wheel, combined with the forward motion of the vehicle is considered. The tyre to road interaction includes the effect of saturation in the force versus brake slip characteristic. After linearization it can be proven that the local derivative of the slip characteristic has a consistent influence on the dynamic behaviour of the tyre. Where the local derivative tends to zero, the maximum achievable brake force is reached. Therefore, assessing the local derivative of the brake force versus slip curve is vital for optimal braking. The phenomenon is also studied in a laboratory environment, with a single braked wheel, running on an electrically driven steel drum of 2.5 m diameter. Special attention is needed for the instrumentation of the wheel rotational speed. To reach the required sample rate and resolution in wheel speed information, the data-acquisition counts the duration of an encoder period. Since this wheel speed signal becomes available at encoder flanges, it needs to be resampled to create data that is synchronous with the input brake pressure and -torque and -force data, typically sampled at 512 Hz. For some conditions and road surfaces (bare steel and ‘safety walk paper’) both the relation between local derivative and resonance gain and the application of this relation as a friction identification methodology will be assessed.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p716.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p335" class="affilation"></a>Intellegent Two Wire Vibration Switch - New Class of Monitoring Device</h2>
<h3>George Zusman</h3>
<p class="affilation">PCB Piezotronics, Depew, NY 14043, USA</p>
<p><b>ABSTRACT</b><br>
This intelligent, two-wire vibration switch is a new type of device for machinery condition monitoring and protection. It has been designed to be a cost effective tool for generating an alarm or initiating shutdown of small to medium-size machinery, such as electrical motors, pumps, cooling towers, fans, and compressors. The vibration switch is designed like universal unit, including an acceptability of any supply voltage from 24 till 265 VAC or VDC, and it is field configurable thru the same two operation wires (pins) by using special USB programmer. Additionally to programmability, vibration threshold of the device is adjustable electronically by external magnet sensor activation technology (Patent and Trademark pending). Construction of the devise provides possibility of electrical connection in series or/and in parallel several units for different applications. The device is entirely self-contained within hermetically sealed, stainless steel housing. The unit’s appearance is very similar to industrial accelerometer and has the same simplicity of installation. In the same time it is based on true RMS vibration velocity measurements switch providing virtual universal compatibility with any type of load, relay, monitoring system, or control device.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p335.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p77" class="affilation"></a>Chain Fault Detection of Escalator Using Handrail Vibration</h2>
<h3>Hiroyuki Tsutada (1), Takashi Hirai (1), Yutaka Itoh (2), Satoshi Shiga (2)</h3>
<p class="affilation">(1) Advanced Technology R&D Center, Mitsubishi Electric Corporation, Tsukaguchi-Honmachi, Amagasaki, Hyogo, 661-8661, Japan (2) Mitsubishi Electric Building Techno-Service Co., LTD., Hishimachi, Inazawa, Aichi, 492-8161, Japan</p>
<p><b>ABSTRACT</b><br>
This paper proposes a new method of chain tension fault detection for escalators. In the conventional method, the handrail chain tension was checked manually by overhauling the escalator. However, the proposed method can detect the loose tension in the chain automatically using an accelerometer attached to the handrail without overhauling the escalator, which is effective for maintenance. First, the transitional pattern of the handrail vibration when starting up the escalator in the reverse direction was studied. The first pattern involves more high frequency vibration generated by starting up the upper sprocket, and the second pattern involves more low frequency vibration generated by starting up the handrail. When tension of the chain that transmits the rotational power of the upper sprocket to the handrail is loose, the time delay between the first pattern and the second patterns, called the “start up delay time”, is increased, because the power transmission from the upper sprocket to the handrail is delayed. Therefore, the loose tension of the chain can be detected by the start up delay time. Based on these characteristics, this paper proposes a method of detecting the start up delay time automatically using signal processing techniques. A chain fault detection system including a single axis accelerometer, a data logger and a wireless communication device was produced, and system tests were conducted to evaluate the performance for several loose tension conditions using real escalators. The test results showed that the start up delay time increased in proportion to the looseness of the chain tension. Therefore, it is possible to detect chain tension faults using the proposed method.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p77.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p636" class="affilation"></a>Spectrum Enhancement of Laser Vibrometer Signals Using a New Speckle Noise Reduction Technique and Angular Resampling</h2>
<h3>Jiří Vass (1), Robert B. Randall (2), Cristina Cristalli (3), Barbara Torcianti (3), Pavel Sovka (1), Radislav Šmíd (1)</h3>
<p class="affilation">(1) Faculty of Electrical Engineering, Czech Technical University, Technická 2, 166 27 Prague, Czech Republic (2) School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney, NSW 2052, Australia (3) AEA s.r.l., The Loccioni Group, Via Fiume 16, 60030 Angeli di Rosora (Ancona), Italy</p>
<p><b>ABSTRACT</b><br>
In this paper, a new method to enhance vibration signals measured by Laser Doppler Vibrometry (LDV) is proposed. The method consists of two stages of processing. The first stage is intended to reduce the speckle noise, an inherent problem of LDV when rough surfaces are measured. The speckle noise causes amplitude dropouts, resulting in undesired “spikes” on the waveform of the velocity signal. It is shown that the presence of the speckle noise depends on the optical level signal (a DC voltage proportional to the amount of backscattered light from the object under investigation). Whenever the optical level is critically low, a new spike is generated and persists until a sufficient value of the optical level is reached. Therefore, speckle noise reduction is achieved by removing all periods of the velocity signal that correspond to the optical level below a specified threshold. The remaining periods are then “connected” using zero crossings in order to form a denoised velocity signal. The second stage is based on an order tracking method recently developed by Bonnardot et al. This method requires no tachometer signal since the instantaneous shaft speed is extracted from the instantaneous phase of a demodulated vibration signal. After the resample times are determined, the denoised signal is resampled in the angular domain by using linear interpolation. As a result, fluctuations of the shaft speed are removed, which reduces smearing of discrete frequency components and thus contributes to sharper peaks in the order spectrum. Finally, spectrum enhancement is also illustrated using the power spectral density and the envelope spectrum. The results indicate that the method can reveal spectral peaks buried in the noise, and thus improve detectability of mechanical faults. The method has been applied to LDV signals measured on washing machines for the purpose of quality control in production lines.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p636.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p4" class="affilation"></a>Diesel Engine Fault Diagnosis Based on Vibration Monitoring and Artifical Neural Network</h2>
<h3>Jianyuan Zhu</h3>
<p class="affilation">Department of Marine Engineering, Shanghai Maritime University, 1550 Pudong Dadao, Shanghai 200135, P. R. China</p>
<p><b>ABSTRACT</b><br>
Health monitoring of the main diesel engine in a ship is very important to ensure the vessel safety and reduce the shipping cost. This paper conducts an investigation on marine diesel engine fault diagnosis based on vibration monitoring and artificial neural network. The engine surface vibration signals are measured and analyzed by use of time series method. The characteristic parameters of engine vibration signals obtained from time series analysis are used to build a suitable artificial neural network using the back propagation algorithm in order to detect the engine operating faults and improve the diagnosis accuracy. The diagnoses of variations in valve clearances and engine cylinder loads are discussed. The relationships between vibration characteristics and engine working conditions are presented. Experimental investigations were carried out on a four-stroke marine diesel engine. The engine surface vibration signals are measured and analyzed for diagnosing the working conditions of valve clearances and engine cylinder loads. The results show that it is feasible and effective to detect the variations in valve clearance and engine cylinder load from engine surface vibration signals. Furthermore, this investigation indicates that the artificial neural networks found for different purposes are feasible for diagnosing the abnormal valve clearances and detecting the cylinder loads of diesel engines, the diagnosis results are veracious and the accuracy is quite high.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p4.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p702" class="affilation"></a>Vibration Fatigue Design Methodology of a Large Scale Heavy Duty Robot</h2>
<h3>Jong Hwi Seo (1), Chul Hwang (1), Yong Won Choi (1), Dong Il Kim (1), Hong Jae Yim (2)</h3>
<p class="affilation">(1) Robotics Technology Lab, Mechatronics & Manufacturing Technology Center, SAMSUNG Electronics Co., LTD. Suwon, South Korea (2) School of Mechanical and Manufacturing Engineering, Kookmin University, SeongBuk-Gu, Seoul, South Korea</p>
<p><b>ABSTRACT</b><br>
The objective of the present study is to develop a design methodology for the large scale heavy duty robot to meet the design requirements of vibration and stress levels in structural components resulting from exposure of system modules to LCD processing environments. Vibrations of the component structures significantly influence on the motion accuracy and fatigue damage. To analyze and design a heavy duty robot for LCD transfer, FE and multi-body dynamic simulation techniques have been used. The links of a robot are modeled as flexible bodies using modal coordinates. Nonlinear mechanical properties such as friction, compliance of motors, gears and bearings were considered in the flexible multi-body dynamics model. Various design proposals are investigated to improve structural design performances using the dynamic simulation model. Design sensitivity analyses with respect to vibration and stresses are carried out to search an optimal design. An example of an 8th-Generation LTR (LCD Transfer Robot) is illustrated to demonstrate the proposed methodology. Finally, the results are verified by real experiments including strain measure test and vibration test.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p702.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p742" class="affilation"></a>Milling Cutting Tools Diagnosis with Higher Order Cyclic Spectra</h2>
<h3>Khalid Ait Sghir (1,2), Mohamed El-Badaoui (1), Bakrim M’hamad (3), François Guillet (1), Driss Aboutajdine (2)</h3>
<p class="affilation">(1) LASPI, IUT de Roanne, Jean Monnet University, 20 avenue de paris, 42334, Roanne, France (2) GSCM_LRIT, Faculty of Sciences, B.P. 1014 Rabat, Morocco (3) Department of Applied Physics, Faculty of Sciences & Technics, BP-549 Marrakech, Morocco</p>
<p><b>ABSTRACT</b><br>
This work presents a diagnostic method to detect faults in milling cutting tools. The proposed method is based on higher order cyclic spectra and is applied to vibration signals. HOS (higher order statistics) are defined in terms of moments and cumulants for the stationary case and HOCS (higher order cyclic statistics) are an extension to the cyclostationary case which characterizes the vibration signal of the rotating machines. The HOCS present an important property; as they enable the detection of the cyclostationarity and the bilinear links in the signal. In general faults in rotating machines are often of a non linear nature, and increase the cyclostationary links in the vibration signals. In this paper, we use angular sampling to make the signals cylostationary. HOCS are estimated by using averaged cyclic biperiodograms. The experimental results based on vibration signals of a tool milling operation sampled in the angular domain show that the HOCS based method is linked to the tool state, i.e. faulty or good, and is able to detect, in the preliminary stage, different fault states, especially wear.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p742.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p334" class="affilation"></a>Investigating the Effects of the Static Cutting Force on the Chatter Vibrations of Milling Process</h2>
<h3>M. Saeidifar, A. R. Ohadi</h3>
<p class="affilation">Mechanical Engineering Department, Amirkabir University of Technology (Tehran Polytechnic), Tehran, Hafez Ave. 424, Iran</p>
<p><b>ABSTRACT</b><br>
A chatter phenomenon is heavy vibration between work piece and tool which causes both a reduced product quality and rapid tool wear. In this paper, a 2-DOF milling process is considered with the symmetric parameters in the feed and normal directions. Then stability lobes diagram (SLD) is derived by the method presented by Altitas in order to find the specific combination of depth-of-cut and spindle-speed, which results in the maximum chatter-free material removal rate. Also the border between a stable cut (i.e. no chatter) and unstable cut (i.e. with chatter) is obtained from solving the time domain delay-differential equations (DDE) by means of the numerical method (4th order Runge-Kutta). The point of interest in this study is that the static part of the cutting force is not ignored and directional dynamic milling force coefficients are utilized in exact form. Finally, numerical results, experimental results from previous works and SLD have been compared. It is observed that the correlation between the numerical and experimental results is much better than the corresponding correlation between the SLD and experimental results.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p334.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p36" class="affilation"></a>Detection of Incipient Bearing Faults in Gas Turbine Engines</h2>
<h3>Michael J. Roemer, Carl S. Byington, Jeremy Sheldon</h3>
<p class="affilation">Impact Technologies, LLC, 200 Canal View Blvd., Rochester, NY 14623, USA</p>
<p><b>ABSTRACT</b><br>
Development of robust and highly sensitive algorithms for detecting incipient bearing faults in gas turbine engines will greatly benefit both military and civil aviation through improved aircraft reliability and maintainability. Techniques including advanced vibration analysis and oil debris monitoring have proven effective in laboratory and industrial settings, but factors including poor transmission of vibration energy from bearings to practical sensor locations and settling of debris in oil scavenge lines have complicated implementation of these techniques in operational gas turbine engines. In this paper, an in-flight gas turbine engine bearing prognostic and health management system is presented that integrates information from damage accumulation models and advanced frequency demodulation techniques to achieve robust bearing health state awareness. After successful laboratory rig tests, the system was implemented on a full size gas turbine engine containing a damaged bearing. Data collected while running the engine in a ground test cell was used to verify and validate the performance of the system.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p36.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p584" class="affilation"></a>Condition Monitoring and Vibration Testing of Centrifugal Pumps</h2>
<h3>Mr. Ravindra S. Birajdar, SM Ballullaya</h3>
<p class="affilation">Product Engineering Division, Kirloskar Brothers Limited, Kirloskarvadi - 416308, Sangli, Maharashtra, India</p>
<p><b>ABSTRACT</b><br>
Condition monitoring is the process of monitoring a parameter of condition in machinery, such that a significant change is indicative of a developing failure. It is a major component of predictive maintenance. The use of conditional monitoring allows maintenance to be scheduled, or other actions to be taken to avoid the consequences of failure, before the failure occurs. It is typically much more cost effective than allowing the machinery to fail. Serviceable machinery includes rotating machines such as centrifugal pumps. Condition monitoring is defined as monitoring the parameters, which affect the life of equipment; e.g. the factors which decide the life of centrifugal pumps are precision alignment, grouting procedure, dynamic balancing of impeller, forces and moments on flanges, vibration, noise, lubricating oil condition etc. In industries like petrochemical, power, oil and gas industries and in nuclear installations, pumps are important equipment right from concept to installation, commissioning and commercial operation. Predicting the residual service life of equipment is difficult but possible. The loss caused by sudden equipment failure may prove to be disastrous to an organization. In a way it hampers production, the down time putting the image of the organization at stake. The techniques developed over a period of time to predict these failures, apart from conventional techniques (look, listen, feel, smell etc.), are Statistical Process Control, Machine Performance Monitoring and Condition Monitoring. The recent development of micro-processor and signal analysis technology has allowed the development of powerful, effective and at the same time relatively inexpensive systems for continuous condition monitoring of different machine parameters. Modern condition monitoring methods have encouraged the manufacturers to invest in new manufacturing technology. Condition monitoring is forcing organizations to take a proactive approach and hence helping them to achieve the operational excellence with the minimum of investment. This paper highlights the available business needs and advanced technologies of condition monitoring in order to determine centrifugal pump condition in testing and operation.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p584.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p814" class="affilation"></a>Machinery Vibration Analysis and Condition Monitoring: A Collaborative Approach</h2>
<h3>Prasad Mandava (1), Craig Outland (1), Ravi Margasahayam (2)</h3>
<p class="affilation">(1) Visual Collaboration Technologies, Detroit, MI, USA (2) NASA John F. Kennedy Space Center, FL, USA</p>
<p><b>ABSTRACT</b><br>
Launch of a space vehicle puts enormous demands on supporting equipment and ground systems that must be safe and reliable so as to guarantee mission success. One such ground system is the NASA’s crawler transporter, a 3 million kilogram behemoth, built in the 1960’s, which moves the 6 million kilogram Space Shuttle to the pad 6-8 kilometers away. This paper discusses vibration analysis and condition monitoring efforts of crawler transporter system components. Modal test and finite element analysis were performed on the crawler transporter systems to assess their vibratory effect on the Space Shuttle Vehicle (SSV). Lastly, focus is on a new software tool to aid engineers and managers who must communicate, collaborate, and visualize modal vibration and structural analysis results, so as to make safe and cost-effective decisions.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p814.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p411" class="affilation"></a>Vibration Analysis of a Beam Carrying a Moving Mass</h2>
<h3>Rabindra Kumar Behera, Dayal R. Parhi</h3>
<p class="affilation">Department of Mechanical Engineering, National Institute of Technology, Rourkela-769008, Orissa, India</p>
<p><b>ABSTRACT</b><br>
This paper deals with the linear dynamic response of a cracked cantilever beam subjected to a moving mass. The velocity of the moving mass is assumed to be constant. The present analysis in its general form may well be applied to beams with various boundary conditions. Results from the numerical solutions of the differential equations of motion are shown graphically. Moreover, when considering the maximum deflection for the end point of the beam, the critical speeds of the moving mass have been evaluated. Experiments have been conducted to compare with the numerical results. It is observed that the experimental results are in good agreement with the numerical one.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p411.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p601" class="affilation"></a>Special Issues Related to Detection of Circumferential Crack at Different Orientations in Pipes by Vibration Method</h2>
<h3>Sachin S. Naik, Surjya K. Maiti</h3>
<p class="affilation">Department of Mechanical Engineering, Indian Institute of Technology Bombay, Mumbai 400 076, India</p>
<p><b>ABSTRACT</b><br>
A vibration based crack detection technique is applied to circumferential cracks in empty straight horizontal pipes with straight front in different orientations with the vertical. The crack is modelled through rotational spring stiffness. The stiffness has been determined experimentally by the deflection and vibration methods for various crack orientations and crack sizes/depths. The rotational spring stiffness for any arbitrary orientation has been theoretically related to the stiffness for the corresponding crack in the vertical orientation. This relation has been compared with experimental results. Some finite element investigations have been done to check the transferability of data from one pipe material and dimensional combination to other materials and dimensional combinations. Further, sensitivity of the vibration method for prediction of crack location on variations in experimental data has been examined. Sensitivity study has been carried out by changing the difference between the frequencies of pipes with and without crack by ±10%. The method is found to be very robust; the absolute maximum variation in location is only 1.45%.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p601.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p11" class="affilation"></a>Response and Prediction of Dynamic Characteristics of Worn Rail Pads Under Static Preloads</h2>
<h3>Sakdirat Kaewunruen, Alex M. Remennikov</h3>
<p class="affilation">School of Civil, Mining, and Environmental Engineering, University of Wollongong, Wollongong, NSW 2522, Australia</p>
<p><b>ABSTRACT</b><br>
Rail pads are a major component of ballasted railway tracks. It helps attenuate the excessive dynamic stress from wheel/rail impact forces in order to prevent premature breakdown of other track components. Based on numerous analytical and numerical models, rail pad plays a crucial role on the dynamic behaviours of railway track. Over years, the rail pads have been worn by the services to carry either passenger or freight train operations. The characteristics of worn rail pads become imperative to maintenance unit as to plan the renewal schedule. Using methods of modal analysis, this paper adopts an instrumented hammer to excite an innovative rail pad test rig, modelled as an equivalent single degree-of-freedom system (SDOF), incorporating a rail pad as a resilient element. The test rig can allow the static preloads to the worn rail pads through the force sensing bolts up to 400 kN at a railseat. The vibration responses are then recorded using Bruel & Kjar PULSE system. The analytical SDOF dynamic model was applied to best fit the experimental modal measurements that were performed in a frequency range of 0-800 Hz. The curve fitting provides the dynamic parameters as the effective mass, dynamic stiffness, and dynamic damping constant, all of which are required for numerical modelling of a railway track. This would lead to a timevariable dynamic evaluation of dynamic behaviour of railway track.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p11.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p12" class="affilation"></a>Artificial Shock Loading Quantities: Experimental Studies into the Influences of Railway Track Environments</h2>
<h3>Sakdirat Kaewunruen, Alex M. Remennikov</h3>
<p class="affilation">School of Civil, Mining, and Environmental Engineering, Faculty of Engineering, University of Wollongong, Wollongong, NSW 2522, Australia</p>
<p><b>ABSTRACT</b><br>
The nature of loading conditions on railway tracks is mostly of shock or impact loads. The shocks are attributed to wheel/rail interaction on one another’s imperfections. There have been a number of investigations on the wheel/rail impacts due to those imperfections and track abnormalities. However, the effect of railway track environments including ballast and rail pads has yet been addressed. Intensive studies on the impact resistance of railway concrete sleepers have been conducted at the University of Wollongong, Australia. In order to understand more clearly the manner in which track components respond to those forces, and to clarify the processes whereby concrete sleepers in particular carry those actions, it is vital to ascertain the spectrum and amplitudes of forces applied to tracks. In addition, artificial impacts replicating the generic actual wheel/rail interaction must be identified, prior to investigating the shock responses of the railway concrete sleepers. This paper presents the experimental studies into the effects on dynamic loading conditions of track environments including the ballast support condition and rail pads. An assembled in-situ concrete sleeper has been constructed and subjected to artificial shock loading using a large capacity drop-weight hammer. The attempts to simulate the repeated impacts due to general wheel flats or engine burns are demonstrated so as to investigate of probabilistic impact failure of the concrete sleepers. The shock loadings under various track environments have been quantitatively monitored and recorded by National Instrument multichannel PXI-SCXI using LabView8. These impacts could eventually lead to cracking and failure of the sleepers, and hence are important in the context of developing the new reliability-based design approach for the railway prestressed concrete sleepers.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p12.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p80" class="affilation"></a>Vibrodiagnostic Method for Determination of the State of Wear of HCR Gear Sets</h2>
<h3>Stanislav Ziaran</h3>
<p class="affilation">Faculty of Mechanical Engineering, Slovak University of Technology, Nám. slobody 17, 812 31 Bratislava, Slovak Republic</p>
<p><b>ABSTRACT</b><br>
The paper is aimed at presenting the basic procedure and methods used for the determination of the state of wear of HCR (High Contact Ratio) gear sets by means of vibro-acoustic diagnostics. After the study and calculation of characteristic frequencies, the author experimentally measured the dynamical behaviour of the gear sets to determine their frequency spectra, as well as to carry out cepstrum analysis. Experiments were carried out on an FZG test gearbox equipped with HCR test gears during one lifecycle. Each frequency spectrum and cepstrum was assigned to a specific percentage occurrence of pitting. Analyzed resulting values of amplitudes of mesh frequency components and their sidebands (and corresponding quefrencies) in the spectrum (and cepstrum) were compared and the state of wear was assigned to each frequency (quefrency) response. The results indicate, that also by means of FFT analysis the incubational time interval of the gear fault can be determined, which is not possible using classical methods.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p80.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p695" class="affilation"></a>Wear Oriented Strategy for Gearbox Remaining Lifetime Estimation</h2>
<h3>Stephan Ebersbach, Zhongxiao Peng</h3>
<p class="affilation">School of Engineering, James Cook University, Townsville, Qld 4811, Australia</p>
<p><b>ABSTRACT</b><br>
Machine condition monitoring of equipment critical to the operation of a plant has become common practice in most industries, both for the detection and progress tracking of faults. Tracking the progression of faults is a measure of the rate of degradation which is often used as an indicator for assessing the remaining lifetime of the machine. The estimation of remaining lifetime without a dedicated strategy will however result in unreliable results. Knowledge of the remaining lifetime of a machine can aid the maintenance department in ordering appropriate replacement parts, plan a machine shutdown or machine replacement. Current techniques are generally concerned with the statistical distribution of failure, which is not always available and may be open to error. A strategy for predicting the remaining lifetime of gearboxes is presented in this paper, based on the wear conditions of components detected by machine condition monitoring. While this strategy can be used to estimate machine lifetimes from new condition, this unique approach also allows the estimate to be updated using machine condition monitoring data. In this way, abnormal operating conditions such as overload and lubricant contamination can be included in the revised estimate. This allows the new strategy to better adjust for changes in operating conditions with potential improvements in accuracy over statistical techniques for this scenario. The strategy has been implemented in an expert system for machine condition monitoring and tested using a spur gearbox laboratory test rig. The benefits of this development promise improved remaining lifetime estimation by taking into account the actual operating conditions experienced by the gearbox to update the estimate. This allows an operator to predict the remaining lifetime of machinery and their associated components in a repeatable and objective manner.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p695.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p692" class="affilation"></a>Smart Condition Monitoring by Integration of Vibration, Oil and Wear Particle Analysis</h2>
<h3>Stephan Ebersbach (1), Zhongxiao Peng (1), Nicole Kessissoglou (2)</h3>
<p class="affilation">(1) School of Engineering, James Cook University, Townsville, Qld 4811, Australia (2) School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney, NSW 2052, Australia</p>
<p><b>ABSTRACT</b><br>
Vibration, oil and wear particle analyses typically represent the core techniques used for machine condition monitoring. While these techniques have been incorporated in many maintenance programs found throughout industry, the results of each analysis are generally considered independently for machine health assessment. Due to the complexity of condition monitoring and the lack of a successful correlation algorithm, the potential benefits of an integrated condition monitoring program have not been realised. This paper outlines the development stages of an expert system designed to perform automated machine condition monitoring of gearbox and associated components faults, by using a correlation algorithm to combine the results obtained from vibration, oil and wear particle analysis. The design aspects of the correlation algorithm are presented in detail, including an analysis of the detection abilities of the three condition monitoring techniques. The development also included a rigorous testing phase which included the verification of all implemented reasoning logic, as well as analysis of laboratory and industry derived data. Some testing results are also discussed, outlining the fault identification ability of the algorithm for typically encountered gearbox faults. The analysis of machine condition data by a correlated approach of vibration, oil and wear particle analysis has a number of benefits compared to conventional condition monitoring practices. These include accurate, efficient and early fault detection of gearbox and bearing faults, as well as the ability to perform root-cause analysis. The automated analysis algorithm permits non-expert personnel to perform routine comprehensive machine condition monitoring, while providing a consistent objective analysis of the machine health.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p692.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p501" class="affilation"></a>System Identification in Stochastic Domain Using System Output Only</h2>
<h3>Sung-Man Park, Woon-Kyung Yeo, Dong-Hee Lee, Kyo-Soon Chae, Jong-Bok Lee, Hoon Heo</h3>
<p class="affilation">Department of Control & Instrumentation engineering, Korea University, 1-5ka, Anam-Dong Sungbuk-ku, Seoul 137-701, South Korea</p>
<p><b>ABSTRACT</b><br>
Most of the study on system identification has been carried out using input/output relation in physical domain. Generally relation between input and output in physical domain gives important information to identify the system. However identification concept of stochastic system has not been reported up to now. Interest is focused to identify an unknown stochastic dynamic system under random external disturbances which is not measurable. A concept to identify the system parameters in stochastic domain is proposed and implemented in terms of simulation and experiment as well. Previously developed stochastic transformation method via F-P-K (Fokker-Planck-Kolmogorov) equation is adopted to estimate the system output. Based on the system output only, it is attempted to identify the system parameters in inverse manner in stochastic domain. Both simulation and physical experiment are conducted to reveal quite noticeable expected performance of the proposed concept.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p501.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p803" class="affilation"></a>Time-Frequency Analysis of Acoustic Signals for Condition Monitoring of Fluid-Filled Pipelines</h2>
<h3>Wenbo Duan (1), Fengshou Gu (1), Andrew Ball (1), Fenglei Jiao (2), Ke Liu (2)</h3>
<p class="affilation">(1) School of Mechanical, Aerospace and Civil Engineering, The University of Manchester, Pariser Building, M13 9PL, UK (2) Chinese Academy of Sciences, 21 Bei Si Huan Xi Lu, Beijing, 100084, PR China</p>
<p><b>ABSTRACT</b><br>
In this paper, a wave propagation model is developed to investigate the wave propagation in fluid-filled steel pipe. Based on the Kennard shell equations the investigation is achieved under the conditions of coupling between the shell elastic acoustic field and the interior fluid acoustic field. Tests are conducted on fluid-filled pipeline blockage detection. An active acoustic source is used to generate acoustic pulse waves into the pipe. The position of the blockage can be obtained from the reflected transient signals. Smoothed Pseudo Wigner-Ville distribution method (SPWVD) has been used to extract the time and frequency features of the propagating waves in the coupling system. Experimental results demonstrate that the proposed approach and SPWVD are effective in detecting the position of the blockage.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p803.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p249" class="affilation"></a>Rolling Element Bearing Fault Diagnosis Based on Genetic Algorithms</h2>
<h3>Yongxiang Zhang (1), R. B. Randall (2)</h3>
<p class="affilation">(1) School of Mechanical and Manufacturing Engineering, Huazhong University of Science and Technology, Hubei, Wuhan, 430074, China (2) School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney, NSW 2052, Australia</p>
<p><b>ABSTRACT</b><br>
The rolling element bearing is a key part in many mechanical facilities and the diagnosis of its faults is very important in the field of machinery health monitoring. Currently the resonant demodulation technique (envelope analysis) has been widely exploited in practice. However, much practical diagnostic equipment for carrying out the analysis gives little flexibility to change the analysis parameters for different working conditions, such as variation in rotating speed, and different fault types. Because the signals from a flawed bearing have features of non-stationarity, wide frequency range and weak strength, it can be very difficult to obtain the best analysis parameters for diagnosis. However, the kurtosis of the vibration signals of a bearing is different from normal to bad condition, and is robust in varying conditions. Secondly, as genetic algorithms have a strong ability for optimization, the authors present a model and algorithm to design the parameters for optimal resonance demodulation using kurtosis as a criterion. The feasibility and effectiveness of the proposed method are demonstrated by experiment and give better results than the classical method of arbitrarily choosing a resonance to demodulate. The method gives more flexibility in choosing optimal parameters than another optimization procedure based on the fast kurtogram.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p249.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p223" class="affilation"></a>Rotor Crack Detection from Vibration Monitoring using a NARMAX Modelling Approach</h2>
<h3>Yongxin Luo, Steve Daley</h3>
<p class="affilation">Department of Automatic Control and Systems Engineering, The University of Sheffield, Mappin Street, S3 3JD, Sheffield, UK</p>
<p><b>ABSTRACT</b><br>
An approach to detect the presence of cracks in rotors and rotor blades through the application of the Nonlinear Auto-Regressive Moving Average with eXogenous inputs (NARMAX) modelling tool, is proposed in this paper. The NARMAX methodology has previously been shown to provide excellent representation for nonlinear system dynamics in the time domain for a wide variety of processes. The initial application of this method is evaluated using rotor crack detection as the objective. In order to check wether the NARMAX approach can obtain both correct model terms and parameters for the underlying system, a developed cracked rotor model has been expanded from a differential equation to a difference equation representation. The study shows that the proposed approach provides a logical procedure for model order selection and nonlinear structure determination and high accuracy is achieved. The crack detection can then be obtained by comparing the resulting signatures with crack free case. Also discussed in the paper is the selection on an appropriate operation status to obtain a good model fit that closely reflect the real system.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p223.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p804" class="affilation"></a>The Investigation of Submerged Vertical Pumps in a Power Plant Using Vibration Based Condition Monitoring Technique</h2>
<h3>Yuk Choi Lee (1), Mirfaizal B. Chuchu (1), Chek Zin Tan (2)</h3>
<p class="affilation">(1) Faculty of Mechanical Engineering, Universiti Teknikal Malaysia Melaka (UTeM), Locked Bag 1200, Ayer Keroh, Melaka, Malaysia (2) Institute of Noise and Vibration, Universiti Teknologi Malaysia, Jalan Semarak, 54100 Kuala Lumpur, Malaysia</p>
<p><b>ABSTRACT</b><br>
Condition monitoring has received considerable and wide attentions through most of the industries employing rotating machinery. It is increasingly becoming vital in industry because of the needs to prolong the machine life, increase reliability and decrease possible loss of production due to faulty machines. Vibration monitoring is the most popular technique, given its direct ability to detect and diagnose faults in machinery, which it is typically found in large industries such as oil and gas, petrochemical and power generation plant. This paper presents the field investigations of submerged vertical pumps with suspected cavitation in a power plant. Frequent impeller failures of submerged vertical pumps would potentially result in the total plant shutdown without warning. Vibration analysis was undertaken on the pump of concern in assist plant personnel in making decision on its operations. The predictive condition monitoring for the pump in the investigation include the vibration monitoring and a simple statistical analysis based on monthly overall vibration level, which is useful for reasonably accurate diagnosis in actual commercial pump in power plant. High frequency vibration was shown to be a good indicator of cavitation. It was shown that the investigations implied a wrong setting of the adjusting screw caused the large gap between the impeller and the casing and therefore enabling the seawater to slip back to the pit and hit the impeller and also the pump operating conditions that had resulted to the impeller failures.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p804.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p309" class="affilation"></a>The Application Study of Force Limited Method in Vibration Tests</h2>
<h3>Zhi-yong Yue, Jun-gang Zhang, Yaoqi Feng</h3>
<p class="affilation">Beijing Institute of Spacecraft Environment Engineering, Beijing 100094, China</p>
<p><b>ABSTRACT</b><br>
Based on a force limited vibration test in the vertical direction of a satellite centertube, this paper introduces the equipment of the force limited vibration test, including the fixture and FMD, force signal acquisition and analysis technique, force transducer calibrating technique, etc. This paper compares the result of the force limited method with the acceleration controlled method, and indicates the influence on control precision and test results of the force limited method. By FEM simulation, this paper analyzes the reason for the lower resonance frequency of the centertube in the force limited vibration test, and discusses the question and solutions relating to the fixture and FMD. This paper was very valuable in the development of force limited method.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p309.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p374" class="affilation"></a>A Modified Green’s Function for a Duct and its Application to the Calculation of the Sound Field Generated by a Piston</h2>
<h3>Alex Zinoviev</h3>
<p class="affilation">Defence Science and Technology Organisation, Maritime Operations Division, Edinburgh, SA, 5111, Australia</p>
<p><b>ABSTRACT</b><br>
A two-dimensional acoustic duct with rigid parallel walls is considered. For such a duct, a novel formula for the Green’s function is derived by means of adding and subtracting the Green’s function for Laplace equation with the boundary conditions of the duct. The Green’s function is used to obtain a new formula for the pressure field generated by a vibrating piston mounted to a duct wall. The formula is a sum of a quickly converging series and a singular integral. It is shown that a singularity in the integral is logarithmic and, therefore, the integral is converging and can be evaluated. The formula derived here as well as a formula derived on the basis of a well-known expression for the duct Green’s function are utilised to calculate the near field of the piston in the area of the duct directly above the piston. The dependency of the pressure on the vertical coordinate above the middle of the piston is calculated. During these calculations, the numbers of terms required for the convergence of the series in both formulae are obtained. It is shown that, with the same criterion of convergence, the formula obtained here requires the number of terms up to one and a half orders of magnitude smaller than the traditional formula. Amplitude and phase discrepancies for both formulae are also calculated. It is shown that the formula obtained here results in the discrepancies up to three orders of magnitude smaller than the traditional formula with the same convergence criterion.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p374.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p164" class="affilation"></a>Determination of Acoustic Properties for Open Duct Termination in Hot Jet Conditions Using FEM Simulation</h2>
<h3>Hans Rämmal, Jüri Lavrentjev</h3>
<p class="affilation">Department of Automotive Engineering, Tallinn University of Technology, Ehitajate tee 5, Tallinn, 19086, Estonia</p>
<p><b>ABSTRACT</b><br>
Determination of the acoustical properties for hot flow duct openings is a classical problem in acoustics. The importance of this issue usually becomes apparent when for instance noise radiation from engine exhaust systems or burner chimneys is considered. In the present study a finite element method (FEM) simulation has been carried out to investigate the effects of high temperature media on the sound propagation through open duct termination. This paper is an extension for the recent experimental work performed by paper authors on acoustical properties of duct terminations exhausting hot gas. In order to simulate the experimental conditions, commercial FEM software COMSOL has been used. The acoustic pressure reflection coefficient of the duct termination is calculated from the complex pressures simulated at the location of two microphones in the test-duct model. Two geometrically different model configurations, based on experimental observations, are studied. The numerical results obtained from simulations are compared to the experimental ones and good agreement between the data is observed.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p164.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p302" class="affilation"></a>An Assessment of Alternative Sensor Technology for Transfer Matrix Measurements in Combustors</h2>
<h3>Jonas P. Moeck, Holger J. Konle, Christian Oliver Paschereit</h3>
<p class="affilation">Institut für Strömungsmechanik und Technische Akustik, Technische Universität Berlin, 10623 Berlin, Germany</p>
<p><b>ABSTRACT</b><br>
Acoustic transfer matrices are an important modeling tool for muffler design and thermoacoustic system analysis. They allow for a relatively simple and modular description of (thermo-) acoustic systems in which only plane waves propagate. However, in case of combustion systems, where the flame transfer matrix (or the scalar flame transfer function) is one of the most important modeling inputs, measuring conditions are quite harsh due to high temperatures (well above 1000 C) and possibly high static pressures. The applicability of two high-temperature resistant pressure sensors to transfer matrix measurements is, therefore, assessed in this work. The first is a probe microphone designed according to the semi-infinite coil principle. As a second alternative, a fiber optic microphone is considered. This less common pressure sensor is built from a thin metallic membrane and a vibrometer detecting the transversal displacement. Two acoustic elements are considered, a uniform duct and a circular orifice. The transfer matrices obtained using the two alternative sensors are compared to measurements with wall flush-mounted standard 1/4" condenser microphones. The results show reasonable agreement and demonstrate the general applicability of the alternative sensors to transfer matrix measurements.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p302.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p678" class="affilation"></a>Generating a “Silent” Flow of Air to Measure the Aerodynamic and Acoustical Performance of a Louvre Under Acoustical Laboratory Conditions</h2>
<h3>Matthew Fishburn, Geoff Colin-Thome’, Peter Alway</h3>
<p class="affilation">National Acoustic Laboratories, Australian Hearing, 126 Greville Street, Chatswood, Sydney, NSW 2067, Australia</p>
<p><b>ABSTRACT</b><br>
National Acoustic Laboratories (NAL) has recently constructed a “silent” airflow system suitable for measuring the acoustical properties and aerodynamic performance of acoustic louvres. A variable speed centrifugal fan capable of producing an airflow of approximately eight cubic metres per second is housed within a reinforced concrete tunnel which provides excellent attenuation from fan breakout noise. The noise generated by the fan is significantly reduced using a custom built silencer. The overall noise reduction provided by the silencer is approximately 56 dB (Lin). Turbulent airflow generated by the system was stabilised using an air plenum in front of the exhaust duct. Regenerated noise due to air turbulence was reduced by acoustically lining the ductwork. The noise level generated by the fan and turbulence in the production of airflow was between 40 to 62 dB(A) at the entrance to the reverberation room testing chamber with an air flow of 2000 to 8500 l/s. When assessing the performance of acoustic louvres under laboratory conditions, particular attention is given to the measurement of the air pressure and temperature of the airflow as these properties influence the rated aerodynamic performance of the louvre. The ‘silent’ airflow has future applications at NAL in measuring the insertion loss and aerodynamic performance of silencers and ductwork.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p678.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p776" class="affilation"></a>Abnormal Resonance Noise of Exhaust Gas Passage in Urban Combined Power Plant</h2>
<h3>Yeon Whan Kim (1), Chun Hee Bae (1), Hyun Lee (1), Young-Shin Lee (2)</h3>
<p class="affilation">(1) Korea Electric Power Research Institute, 103-16, Munji-dong, Yuseong Gu Daejon, 305-380, Korea (2) Department of Mechanical Design Engineering, Chungnam National University, Director of BK 21, Mechatronics Group, 220 Gung-Dong, Yuseong, Daejeon, 305-764, Korea</p>
<p><b>ABSTRACT</b><br>
A diffuser of an industrial gas turbine is annular with structural members, called struts, in the exhaust gas flow path. The high noise coinciding with the pressure pulsation tone produced in the combustion cans has been measured near the strut of the gas turbine flue gas passage since the commercial operation of urban combined power plant site in Korea. The pulsation frequency by combustion stimulated the radial standing acoustic resonance of the strut. The abnormal exhaust noise transferred through stacks caused inhabitant to complaint. The acoustic resonance phenomenon in the exhaust passageway of gas turbine was the main noise source of public complaint. Threshold for 585 Hz pulsation from the combustion cans is 3 - 18 kpa, rms. When the load is 80-95% of full, pulsation levels are magnified >100 pa, rms at downstream of diffuser and has 585 Hz component; then, the sound pressure level shows > 101 dBA at the top point of the stack. It shows that the noise complaints around the power plant are caused by the resonance phenomena in GT flue gas passage. Baffle silencer is applied to isolate the abnormal noise frequency band into the stack; therefore, the measures obtained insertion loss of 20 dBA.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p776.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p612" class="affilation"></a>Recent Approaches to Environmental Noise Monitoring and Estimation of its Influence to the Health of Inhabitants</h2>
<h3>Andrei V. Vassiliev</h3>
<p class="affilation">Department of Mechanics and Environmental Protection, Togliatti State University, Togliatti, 445667, Belorusskaya Str., 14, Russia</p>
<p><b>ABSTRACT</b><br>
Environmental noise impact may cause serious negative problems for inhabitants. Problems and approaches of noise monitoring of urban territories are discussed. Environmental noise monitoring includes not only noise measurement, analysis, and mapping, but also estimation of noise influence to the health of inhabitants. Noise measurement results of the living territory of Samara region and of Togliatti city, Russia, are considered as an example of noise monitoring approach practical realization. Dynamic noise maps of living territory of Togliatti city were created. Estimation of noise influence to the population of Togliatti city has been done. Results allow the author to make a conclusion about the existing of the real problem of noise safety of the city.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p612.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p749" class="affilation"></a>Health and Safety Effects of Vibrations in Helicopters</h2>
<h3>Anthony Wagstaff, Jan Ivar Kåsin</h3>
<p class="affilation">Norwegian Defence Medical Services - Institute of Aviation Medicine, 0313 Oslo, Norway</p>
<p><b>ABSTRACT</b><br>
Helicopter operations imply Whole-Body Vibration (WBV), primarily due to the motions of the main rotor system. Health effects of WBV in general have primarily been related to the spine and it’s related structures. However, many other effects are present, some of them having potential health implications while others may affect safety by acting on the human operator’s physiology. Methods and Discussion: Probable and possible vibration effects in helicopters are reviewed, both from possible mechanisms and epidemiological data. Low Back Pain (LBP) is possibly the best documented physiological effect, however, LBP in helicopters is only partly due to vibration. Other physiological effects, e.g on the neck and on the visual system may have safety consequences. The possible entity of Vibro-Acoustic Disease (VAD) is also discussed in relation to helicopter aircrew. Problem areas and possibilities in relation to reducing vibration in helicopters include considerations of the vibration levels and axes as well as crash protection.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p749.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p354" class="affilation"></a>Regulating the Rapidly Developing Oil Sands Industry in Alberta and its Implications on Environmental Noise Monitoring and Assessment</h2>
<h3>Carolyn Decock (1), Teresa Drew (2), Roger Treagus (2)</h3>
<p class="affilation">(1) Golder Associates Pty. Ltd., 611 Coronation Drive, Toowong, QLD 4066, Australia (2) Golder Associates Ltd., 1000 940-6th Avenue S.W., Calgary, Alberta Canada, T2P 3T1</p>
<p><b>ABSTRACT</b><br>
Alberta is rapidly developing its extraction industries to mine oil out of sand (oil sands) with currently estimated reserves of 1.7 to 2.5 trillion barrels of oil. The provincial environmental regulator is the Alberta Energy and Utilities Board whose charter includes regulating and facilitating energy development in Alberta. In 2007, a stricter noise code is being introduced which includes mandatory compliance with 40 dB(A) at 1.5 km from a facility, regardless of whether receptors are present. As well, monitoring, modelling and reporting procedures have changed from previous practice and these are described. The influence of Alberta’s regulatory path with other provinces is also described. In western Canada, the most significant stakeholders after government are First Nations groups. First Nations people in Canada have land treaties with the Canadian government that have been in existence since the settlement of Canada. These treaties have allowed First Nations people in Alberta to maintain their traditional ways and gain from the development. First Nations people in Canada have a significant amount of influence in the environmental approval process. Their role in the project approval process, including noise issues is discussed. Health Canada, the National Government’s Health Authority is also a significant regulator with concerns focusing around land use, controlling sleep disturbance and cumulative impacts. Health Canada’s draft 2005 guidelines and the effects of these guidelines to Alberta’s development are briefly examined.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p354.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p827" class="affilation"></a>Optimising the Application of European Directive 2003/10/CE Performing Simple WED<sub>007</sub> Dosimetry</h2>
<h3>Christine Aujard (1), Laurent Faiget (1), Fernand Dupont (1), Patrice Pischedda (2)</h3>
<p class="affilation">(1) 01dB-Metravib, Environment Division, R&D Department, Limonest, France (2) 01dB-Metravib, Asia Pacific Director, Kuala Lumpur, Malaysia </p>
<p><b>ABSTRACT</b><br>
European Directive 2003/10/EC requires that noise exposure be taken into account in order to improve working conditions in industry. To meet these requirements, 01dB-Metravib has developed the most relevant device to date, combining technological performances and userfriendliness. Based on wireless communication through a Pocket PC, Wed007 can measure sound levels simultaneously in dB(A), dB(C) and peak(C). Levels exceeding (135, 137 and 140 dB) peak levels are recorded. Based on these results, software dBLexd computes exposure Lex,8h. The dimensioning of suitable solutions can then be efficiently contemplated.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p827.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p813" class="affilation"></a>The challenges of noise control in hospitals</h2>
<h3>Ilene J. Busch-Vishniac(1), James E. West(2), Phillip Kwon(1) and Jeffrey Dunn(2)</h3>
<p class="affilation">(1)Mechanical Engineering Department
Johns Hopkins University
3400 N. Charles Street
Baltimore, MD 21218
US
(2)Electrical and Computer Engineering Department
Johns Hopkins University
3400 N. Charles Street
Baltimore, MD 21218
US</p>
<p><b>ABSTRACT</b><br>
Over the past few decades, the noise in hospitals has been monotonically rising and is now sufficiently high that speech communication clarity is a concern. The reason hospitals are noisy is clear: the density of people is very high, most of them are ambulatory, and all of them communicate primarily through speech. Add to this mix alarms, a paging system, electronic equipment, mandated high rates of air flow and you have a recipe for acoustic pandemonium. Further, the ability to control the noise through traditional approaches, such as sound absorbing material, are limited by hygiene considerations. In this talk we characterize interior hospital noise and discuss approaches to its reduction. Our focus is on noise control strategies that will work long term because they involve objective changes in the facilities and sound environment rather than behavioral changes in people.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p813.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p87" class="affilation"></a>Noise Control Projects: the European Experience</h2>
<h3>Marc Asselineau</h3>
<p class="affilation">Peutz & Associates acoustical consultants, 34 rue de Paradis, F75010 Paris, France</p>
<p><b>ABSTRACT</b><br>
Various European Directives have been drafted over the years in order to cope with such problems as occupational noise, community noise control, urban noise, and environmental noise. The implementation of those directives is usually done by means of the national legislations but also through the European standards. The problem often is to issue a text that is compatible with each local custom (e. g. the “evening” can be quite a different period for a Dutch or for a Spaniard!). Therefore some interpretation can sometimes be needed and it is not uncommon for a foreign company seeking to open new premises to ask for clarification and advice to a consulting engineer. This paper submits an overview of some national regulations based on European directives and relevant standards. It is illustrated using case studies on façade insulation near transportation corridors, community noise, building noise control and occupational noise.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p87.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p691" class="affilation"></a>The Case for Spectral Baseline Noise Monitoring for Environmental Noise Assessment</h2>
<h3>Michael Caley, John Savery</h3>
<p class="affilation">Savery & Associates Pty Ltd, Brisbane Queensland</p>
<p><b>ABSTRACT</b><br>
Norms of baseline environmental noise monitoring practice have historically been influenced by available instrumentation, often to the detriment of the technical needs of a monitoring situation. Within Australia instrumentation that has been designed for broad-band traffic noise measurement at relatively high ambient noise levels is often used to measure low ambient noise environments where the results are critical to the impact assessment of major infrastructure projects. Often these noise environments contain significant seasonal and episodic biological noise. A particular difficulty with traditional broad-band noise loggers deployed in relatively low noise environments is the inability to identify the contributions of seasonal and episodic noise sources such as insect and frog noise, resulting in an elevated assessment of baseline noise levels. Consequences of this limitation include:- difficulty achieving repeatability of ‘longterm’ baseline noise monitoring results by different acoustic practitioners; aggregate measures of diurnal noise patterns can appear counter-intuitively skewed, with night ‘background’ noise levels matching or even exceeding daytime ‘background’ noise levels; and environmental license conditions can be unintentionally overly permissive if based on the results of broadband noise measurements that include seasonal biological noise. A related issue that is briefly discussed is the need for baseline noise monitoring to provide a baseline noise spectrum shape to assist in determining the audibility of an introduced noise source. Spectral baseline noise measurements enables evaluation of the content of baseline noise records, and in particular, the contribution of biological noise sources that may be present seasonally, or episodically. Examples are presented that contrast the conclusions that can be drawn from spectral baseline noise monitoring compared with traditional broad-band noise logging.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p691.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p583" class="affilation"></a>Experimental Outdoor Sound Propagation and ENM</h2>
<h3>Najah Ishac</h3>
<p class="affilation">ERM Australia Pty Ltd, Pyrmont, NSW 2009, Australia</p>
<p><b>ABSTRACT</b><br>
Noise propagation is significantly affected by prevailing meteorological conditions. Several standard modelling methods rely on measured meteorological data and estimation techniques. We decided to obtain realistic and actual noise level data including the effect of atmospheric conditions by conducting a three week experiment on sound propagation. Loud speakers were placed at a central location on a site, to be used as an artificial sound source. A constant sound signal of a set of pure tones with varying sound intensity levels between each frequency is constantly producing sound at a fixed emission level for several hours at a time each night. The primary frequencies in the source signal were chosen to adequately simulate the main frequency range of typical mining plant. The transmitter consists of a CD player with a CD containing the source noise, a power amplifier and loud speakers. The arrangement is powered by a petrol generator, all located in an open area. The sound was recorded by acoustic consultants at distant off-site locations, as well as at near-filed positions 20 m from the speakers. There were two personnel conducting measurements simultaneously, each with a Type1 narrow band analysers SVAN912. The operators collected random 1-minute samples at various locations and times through each monitoring period. Meteorological data is continuously collected by a weather station near by. Each narrow band sample was then analysed to filter the discrete pure tones from the ambient noise recorded. In the first instance the fluctuation of absolute source contribution at each monitoring site is quantified. The meteorological and noise data is correlated and analysed to quantify the effects of weather on noise propagation. These measurements are compared to predictive output from a detailed three-dimensional model developed using ENM. The comparison shows interesting divergence of results but with encouraging correlation in noise levels on average.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p583.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p168" class="affilation"></a>Noise in Hospital Areas - Measure and Evaluation</h2>
<h3>Salvatore Barbaro, Rosario Caracausi</h3>
<p class="affilation">Department of Research in Energetics and Environment, University of Palermo, Viale delle scienze., 90128 Palermo, Italy</p>
<p><b>ABSTRACT</b><br>
The territory of Palermo will be acoustically subdivided into homogeneous areas. In the present job, our attention is focused on the zones in class I that includes particularly sensitive areas as schools and hospitals. The acoustic climate inside and outside some hospital of Palermo (Italy) is carried out. The hospitals were built in highly urbanized areas. Around the areas important roads are present, with high traffic. With a campaign of measures, in proximity of the roads, in the hospital square, in the parking, and finally inside the hospital areas, the equivalent level and the patients exposure were calculated as Ld, Ln and DNL. Both the impact due to the roads (considered as external source) and due to internal traffic, equipments, tools of waste treatment (considered as internal source), has been analyzed. The comparison between noise values and normative limits allows us to evaluate the entity and the priority of the interventions.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p168.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p826" class="affilation"></a>No Worries - How to Handle Acoustical Planning Problems with Noise Calculation Software</h2>
<h3>Wolfgang Probst</h3>
<p class="affilation">ACCON GmbH and DataKustik GmbH, D-86926 Greifenberg, Germany</p>
<p><b>ABSTRACT</b><br>
Prediction and assessment of noise is extremely important in the planning phase of new roads, railway tracks, industrial facilities or airports near cities and other built up areas. The calculation of noise levels allows a detailed analysis of the source influence and the spatial distribution presented as noise map is an excellent basis to optimize the layout of all planned constructions. Several tools have been developed to support the architects and planners in their task to rank different solutions, to implement effective noise mitigation measures and to find the optimal alternative with respect to noise. Some of these techniques are demonstrated.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p826.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p380" class="affilation"></a>Acoustic Performance of First Generation Apartment Houses in Korea</h2>
<h3>Yang Ki Oh, Seong Il Hwang, Mun Ki Chu</h3>
<p class="affilation">Department of Architecture, Mokpo National University, Muan, Chonnam 534-729, South Korea</p>
<p><b>ABSTRACT</b><br>
Traditional life style in Korea has been established for thousands of years in detached houses. However, apartment houses have been introduced in the urban areas to serve the need of industrialization since the 1970’s. To give a more rapid supply, building performance such as acoustic quality was not a significant matter at the stage of building. Furthermore the acoustic quality is getting worse as time goes by, the building is getting older and the urbanization is progressing more. They have two or three bedrooms, areas mostly from 65 m<sup>2</sup> to 85 m<sup>2</sup>. There are usually 6 to 8 units in a floor, which are arranged linearly. 150 mm to 200 mm thick transverse load bearing walls and longitudinal beams structurally support the building. There had not been an anti earthquake design code in Korea. There are complaints about the acoustic quality of the old, first generation apartments in Korea. A recent survey shows that there are five major aspects. They are floor impact noise, heavy weight floor impact noise, plumbing noise, sound transmission between units in the same floor, and traffic noise. Surveys on the acoustic complaints, measures of the current performance on the five major acoustic aspects, and a comparison of the results with the residents’ expectations and with legal considerations are performed in this study.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p380.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p127" class="affilation"></a>Observation of Pure Frequencies in Bioresonance Vocal Sounds</h2>
<h3>Anna Bacchia, Giovanna Fiore, Melisa Rossi</h3>
<p class="affilation">Anna Bacchia Vocal Sound Laboratory, via Al Bosco 75, Aldesago, 6974 Lugano, Switzerland</p>
<p><b>ABSTRACT</b><br>
Relaying on present knowledge of bio-resonance and bioenergetics, the correlations between the frequencies of human voice and the energetic equilibrium of human body are becoming more manifest. Based on our previous researches it has been shown that bio-resonance treatments imply significative variations on the human organism energetic equilibrium. In this context an experimental research on what we have called pure frequencies, observed under particular conditions during applications of bio-resonance vocal sounds, is presented. The aim of this work is to expose how the human voice performing the bio-resonance can undergo a peculiar phenomenon which shows a frequency spectrum different from an ordinary one. Considering the complexity of variables involved in the experiment, this work also points out the need of new interpreting models not restricted to the common cause-effect forma mentis which characterizes the scientific method approach. The spread of quantum physics interpretations into other disciplines like medicine and psychology is becoming a fertile soil for the creation of such new models.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p127.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p20" class="affilation"></a>Effects of Temporarily Limited Noise Calming Periods During Sleep</h2>
<h3>Barbara Griefahn, Anke Marks, Sibylle Robens</h3>
<p class="affilation">Institute for Occupational Physiology at Dortmund University, Ardeystr. 67, 44139 Dortmund, Germany</p>
<p><b>ABSTRACT</b><br>
As traffic density will increase in the forthcoming years, more during the shoulder hours and during the night than during the day and due to the deleterious effects of noise on sleep this paper evaluates 3 models of temporary quiet periods during the night. As the times of these periods are oriented to the sleep behaviour of the majority of the adult population persons with different bedtimes are concerned. Twenty-four healthy young persons (12 women, 12 men, 21 - 27 yrs) slept in 2 consecutive weeks, four nights each week in the laboratory while during one week each exposed to road or railway noises. Three models of temporary quiet periods were realized: two starting at 11 pm and lasting 4 or 6 hours and one starting at 3 am and lasting until 7 am. Eight normal sleepers went to bed at 11 pm, eight early sleepers at 10 pm and eight late sleepers at 12 pm, wake-up call was eight hours later. The overall 9 exposure patterns were reduced to three main exposure patterns, defined by the quiet period in the beginning, in the middle or at the end of the subjective night. During all nights polysomnograms were recorded continuously, sleep was evaluated subjectively every morning. Noise in the beginning of the night caused disturbances before and shortly after noise onset. If the night is terminated by a quiet period only, the initial disturbances are fully compensated. However, whenever the subjective night is terminated with an even short noise period, sleep structure and subjective evaluation of sleep are significantly impaired. Thus, whenever a temporary quiet period during the night is considered, it is strongly recommended to locate this period at the end of the subjective night. In any case late sleepers profit less from such regulations.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p20.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p237" class="affilation"></a>Cochlear Mechanics, the Acoustic Reflex and Noise Induced Hearing Loss</h2>
<h3>David Alan Bies</h3>
<p class="affilation">103 Callaghan St, Mooroobool, Cairns, QLD 4870, Australia</p>
<p><b>ABSTRACT</b><br>
In a noise environment devoid of impulsive sounds the ear responds as a linear system to levels sufficient to destroy it in response to energy input. In such environments a long time average A-weighted measurement will provide a suitable measure of exposure. In an environment characterised by impulsive sounds, however, it is proposed that the response of the ear is determined by the response time as well as the on-time of the acoustic reflex and the durability of the hair cells. Pickles has stated, “the reflex is too slow to protect the ear against impulsive noise,” which is true of a single impulse, however, in an environment characterised by many impulses the effectiveness of the reflex may also depend upon the durability of the hair cells, as well as the reflex on-time. It is proposed that the acoustic reflex can respond quickly enough to reduce sound transmission enabling the ear to respond as a linear system in the low frequency range to 2 kHz however, it cannot respond quickly enough to enable linear response in the high frequency range above 2 kHz. Consequently, in the high frequency range of 4 kHz, where the ear is most sensitive, the ear responds to impulsive sounds as a non-linear system where destruction of the ear is proportional to peak pressure. On this basis the well known “4 kHz dip” may be explained.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p237.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p553" class="affilation"></a>Acute Effect of a Helicopter Flight on Cellular Tissue Biochemical Markers</h2>
<h3>Jan Ivar Kåsin (1), John Kjekshus (2), Anthony Wagstaff (1)</h3>
<p class="affilation">(1) Norwegian Defence Medical Services - Institute of Aviation Medicine, 0313 Oslo, Norway (2) Rikshospitalet University Hospital - Department of Cardiology- 0027 Oslo, Norway</p>
<p><b>ABSTRACT</b><br>
Whole-body vibration and noise are inherent characteristics of helicopter operations. The helicopter pilot is affected by vibration from both low-frequency noise and mechanical vibration sources. The way this energy is transmitted to different tissues and organs depends on intensity, frequency and resonance phenomena within the body. Whole body vibration is known to affect the muscular and skeletal system in the lower part of the spine. How each single cell responds to this stimulation is, however, less known, but some studies have described chronic pathological changes in different types of tissue in persons exposed to low-frequency noise and vibration. The aim of the present study was to investigate possible cellular reactions to an acute exposure to low frequency noise and vibration in a helicopter. 13 male subjects were subjected to a 3.5 hr helicopter flight in a in a Westland Sea King Rescue helicopter. Blood tests were taken before and after the flight and analyzed for more than 80 parameters including cytokines and other biochemical markers of low-level tissue irritation. Subjects were their own controls. No statistically significant changes in cytokines or other indicators of low-level tissue irritation were found after controlling for normal variation in the control blood tests. Some blood values changed significantly, however different explanations are possible for these findings. An acute exposure to helicopter noise and vibration caused no statistically significant changes in known sensitive tissue biochemical markers. Further studies are needed to explain chronic pathological changes found by other researchers</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p553.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p441" class="affilation"></a>Correlation between SIL and SII in a Light Aircraft Cabin During Flight</h2>
<h3>Tino Bucak, Ernest Bazijanac, Biljana Juričić</h3>
<p class="affilation">Department of Aeronautics, Faculty of Transport and Traffic Sciences, University of Zagreb, Vukelićeva 4, Zagreb 10000, Croatia</p>
<p><b>ABSTRACT</b><br>
Several reports confirm that high levels of interior noise in small GA aircraft considerably downgrade the quality of speech communication, confirming this setback as a serious flight safety issue. In order to quantify the levels of interaction between cockpit speech and noise, numerous octave-band noise measurements in Cessna 172R cabin have been conducted during various flight conditions, from which Speech Interference Level (SIL) and Speech Intelligibility Index (SII) were derived. The subsequent comparison of the results was made and presented in this paper. Although based on different grounds, these two methods have shown acceptable degree of correlation under given conditions.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p441.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p320" class="affilation"></a>Ride Comfort Evaluation for the Korean Experimental High-Speed Train</h2>
<h3>Young-Guk Kim, Sunghoon Choi, Seog-Won Kim, Ki-Hwan Kim</h3>
<p class="affilation">Korea Railroad Research Institute, 360-1, Woulam-dong, Uiwang-city, Kyonggi-do, 437-825, Korea</p>
<p><b>ABSTRACT</b><br>
Ride comfort is one of the most important dynamic performance characteristics of railway vehicles and it is affected by various factors such as vibration, noise, smell, temperature, visual stimuli, humidity and seat design. Evaluating ride comfort is not simple because all these factors must be considered simultaneously. In general, vibration, which originates from vehicle motion, is taken as the primary concern. The vibration of railway vehicles becomes very complex because it is affected by the condition of vehicles, including wheel profile, suspensions and equipments in the vehicles, and the condition of track sections, including rail profile, rail irregularities, cant, and curvature. In addition, operating conditions, such as frequent starts or stops and speed restrictions, are also major factors that affect the vibration of railway vehicles. This paper deals with the ride comfort of HSR-350x, a proto-type train developed in Korea since 2002. In order to evaluate the ride comfort of a railway vehicle, it is very important to consider the correlation between passenger’s feeling and vibration of the vehicle. Human feelings vary with frequencies of vibration even if the intensities for all frequencies vibration are equal, as in the case of acoustic noise. Therefore, a weighted vibration considering human feeling has been used to evaluate the ride comfort of HSR-350x. A total of 362 ride indices have been acquired by the statistical evaluation method UIC513 at train speed of 80-310 km/h from 2002 to 2006. The characteristics of ride comfort for HSR350x have been investigated considering the operation conditions, such as load/track conditions, seasons and annual variations.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p320.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p549" class="affilation"></a>The Effects of Low-Frequency Vibrations on Control Profile of Blood</h2>
<h3>Zbigniew Damijan</h3>
<p class="affilation">Department of Mechanics and Vibroacoustics, Faculty of Mechanical Engineering and Robotics, AGH University of Science and Technology, Al. Mickiewicza 30, 30-059 Cracow, Poland</p>
<p><b>ABSTRACT</b><br>
Vibrating platforms are widely employed in sport facilities and fitness clubs to help people develop muscles and improve their physical condition. The applied vibration frequencies ranged from 30 to 60 Hz and vibration’s amplitudes were regarded as “considerable”. There are few reports in literature on the potential applications of low-frequency vibrations in therapy (e.g. Military Hospital in Busko, Poland. Therefore, a research program was undertaken at the AGH University of Science and Technology to investigate the effects of low-frequency vibration on selected parameters of control profile (urea, creatine, bilirubin, transaminase ALT, transaminase AST, alkaline phosphatase, albumin, total protein, calcium, phosphorus) of human blood. Cyclic fluctuations of bone loading were induced by the applied harmonic vibration 3.5 Hz and amplitude 4 mm. The experiments utilising two vibrating platforms were performed in the Laboratory of Structural Acoustics and Biomedical Engineering AGH-UST. The applied vibrations were harmless and not annoying, in accordance with the standard PN-EN ISO 130901-1, 1998. 28 women volunteers had 19 sessions on subsequent working days, at the same time of day. During the tests the participants remained passive, in the standing position. This paper is the continuation of the study covering the effects of low-frequency vibrations on selected physiological parameters of the human body. The experiments were conducted to find to answer whether vibration’s exposure (total duration of training sessions 6 hours 20 min) should produce any changes in control profile of blood. Research data showed that low-frequency vibrations can be treated as isometric physical training and might be well applied to support the therapy of numerous civilisation-related diseases, such as: overweight, hypertension, osteoporosis and anaemia. Research data also reveal a statistically significant decrease of phosphorus, total protein and bilirubin levels in blood serum.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p549.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p680" class="affilation"></a>Dollars and dB. the Cost of Conservative Acoustics in Industrial Noise Control</h2>
<h3>Colin Speakman</h3>
<p class="affilation">Parsons Brinckerhoff Australia Pty Ltd, 12th Floor, IBM Centre, 348 Edward St, Brisbane, QLD 4001 Australia</p>
<p><b>ABSTRACT</b><br>
The objective of this paper is to demonstrate the costs involved in industrial acoustic projects and in particular the additional costs due to conservative acoustic assumptions made at various stages of the project. Industrial noise control projects are typically made up of a number of stakeholders such as; legislators, plant operators, equipment suppliers, acoustical consultants and noise control manufacturers. A typical industrial acoustic project will involve input from each of these stakeholders. All stakeholders have an interest in ensuring that the project, either, does not exceed the legislated limits, meets the specifications or simply performs as expected. Commonly, conservative assumptions made by one stakeholder are not communicated to the various other stakeholders leading to compounding conservatism. The process of compounding conservatism and its effect on the final project cost is discussed. This paper uses a number of examples to demonstrate how the cost of a project can escalate due to each additional level of conservatism.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p680.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p338" class="affilation"></a>Noise in the Intensive Care Unit (ICU)</h2>
<h3>Daniela T. Cianci, S. Kanapathipillai</h3>
<p class="affilation">School of Mechanical and Manufacturing Engineering, The University of New South Wales, Sydney 2052, Australia</p>
<p><b>ABSTRACT</b><br>
A comprehensive literature review of noise levels in the hospital intensive care unit (ICU) revealed that noise is a problem in the ICU. Numerous studies conducted in overseas hospitals consistently found that the noise levels exceeded recommended levels. Patients in the ICU are in a critical condition. Noise can prevent a person from sleeping and can be offensive. Sleep deprived patients may experience slow tissue growth and depression coupled by the strain of being in a serious state of health. A study was conducted that involved a noise level analysis of a prominent Australian hospital’s ICU. It found that the noise levels exceeded the maximum recommended design sound level prescribed by Standards Australia Investigation into the cause of the high noise levels revealed a number of sources. Recommendations were made to reduce noise levels in the ICU and design features were suggested that could reduce sound exposure to the patients.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p338.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p643" class="affilation"></a>Noise Control in Hydroelectric Stations</h2>
<h3>Silviu Platon</h3>
<p class="affilation">National Institute for Research and Development for Labour Protection, Budisteanu Street 15, sector 1, Bucharest-010773, Romania</p>
<p><b>ABSTRACT</b><br>
One of the most important physical hazard agents very often present in the work enviroment of hydroelectric stations is noise. Noise is an aggresive hazard agent wich acts in time on safety and health of the workers and is one of the main causes of accidents and occupational diseases occured in such hydroelectric stations. The necesity of reducing the noise under the maximum accepted limits in the hydroelectric stations comes from the will to protect the safety and health of workers and well as from legal obligations to create a work enviroment according to the European Union regulations in force on the daily noise exposure of workers. The main target wich needs to be followed for noise control in the hydroelectric stations is to reduce the recurrence of occupational deafness. The second target wich must also be taken into account is represented by the protection under effects of noise (providing intelligible speaking). The third objectiv but not the last one wich needs to be followed seriously when reduction to noise exposure is aimed at is the acustic confort in a human community both in the work environment or outside it. Noise control in the hydroelectric stations is also a system matter, system wich includes the source, means of transmission (routes of the acustic propagation energy) and receiver. The methods wich need to be taken into consideration when reduction of noise exposure of workers in the hydroelectric stations is aimed at must be incorporated in that system. Such methods of noise control are included in one or several of the following categories: <ul> <li>methods on noise control at source;</li> <li>methods on noise control on the transmission routes;</li> <li>methods on noise control at the receiver</li></ul></p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p643.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p113" class="affilation"></a>The Mechanism of Noise Formation and Calculation of Noise Characteristics of Underexpanded Steam Jets</h2>
<h3>Vladimir Tupov, Dmitri Chugunkov</h3>
<p class="affilation">Moscow Power Engineering Institute (Technical University)(MPEI), Krasnokazarmennaya st., 14, 111250 Moscow, Russia</p>
<p><b>ABSTRACT</b><br>
In technological processes of various plants and facilities, steam and gas at excess pressure is often vented. As a result of such emissions, underexpanded supersonic turbulent jets are formed, which create a sound field exceeding background levels by up to 30...40 dBA within a radius of several kilometers. Forecasting noise characteristics of air venting of steam and gas is important even at the design stage, to facilitate the development of noise control measures. Here, on the basis of research led by the authors, results are presented for the numerical simulation of the venting of underexpanded steam and gas jets into the atmosphere. The specific mechanism of noise formation and a new method of predicting the noise characteristics of steam jets are also presented.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p113.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p514" class="affilation"></a>Development of a Silencer for Acoustic Enclosures</h2>
<h3>Jun-Shin Lee (1), Wook-Ryun Lee (1), Seok-Man Shon (1), Hong-Jun Ahn (1), Young-Dal Kim (2), Jae-Myung Shim (2)</h3>
<p class="affilation">(1) Korea Electric Power Research Institute, 103-16 Munji-Dong, Yuseong-Gu,Taejon, 305-380, Korea (2) Department of Electrical Engineering, Hanbat National University, San16-1, DuckMyoung-Dong, Yuseong-Gu, Taejon 305-719, Korea</p>
<p><b>ABSTRACT</b><br>
An acoustic enclosure is widely used to reduce the sound pressure level propagating from the noise source. However, the performance of acoustic enclosure is decreased by its inherent limitations such as temperature rise or acoustic pressure which is built up inside the enclosed space. In this study, a silencer is installed to overcome these limitations, for large amount of air should be move through it. For this purpose, a parallel baffle-type duct silencer with acoustic resonators is studied to reduce the transmitted noise from a transformer. By using the silencer, the high-frequency components of the transmitted noise above 360 Hz can be effectively absorbed by the parallel baffles and the harmonic components such as 120 Hz and 240 Hz can be reduced due to the presence of Helmholtz resonators. As a result large sound attenuation is achieved by applying the silencer to large transformers in an actual electric substation.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p514.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p226" class="affilation"></a>Simulation of Engine Vibration on Nonlinear Hydraulic Engine Mounts Through Full-Vehicle Model</h2>
<h3>A. R. Ohadi (1), Gh. Maghsoodi (2), V. Fakhari (1)</h3>
<p class="affilation">(1) Mechanical Engineering Department, Amirkabir University of Technology, Tehran, Iran (2) Automotive Engineering department, Iran University of Science and Technology, Tehran, Iran</p>
<p><b>ABSTRACT</b><br>
This paper represents the simulation of vibrational behaviour of engine on nonlinear hydraulic mounts. Inertia track and decoupler are included in the model of hydraulic engine mounts and nonlinear factors such as inertia and decoupler resistances in the turbulent region are considered. In order to investigate the responses of the engine under engine and road excitations, engine is located on the 7 DOF vehicle model through its three hydraulic mounts. Primarily, the nonlinear properties of hydraulic mount are identified and a lumped parameter mathematical model of the mount is developed. After that, a thirteen degree of freedom full vehicle model including six degree of freedom for translations and rotations of engine, three degree of freedom in bounce, pitch and roll for sprung mass and one degree of freedom in vertical displacement for each four unsprung masses are developed. The 6 degree of freedom four cylinders V-shaped engine under inertia, balancing masses and mounting reaction forces and torques is considered. In deriving the governing equations of motion of sprung mass, the force exerted by the suspension system on the sprung mass and also the reaction forces from engine mounts are considered. Simulation results can be used to predict the dynamic responses of the system under engine and road excitations in the time and frequency domains. By solving the time domain nonlinear equations of motion of full vehicle model, translational and rotational motions of sprung mass and engine’s body are obtained for different engine speeds and base excitations. Transmitted base forces are also determined for each loading condition. Using FFT, the response of the system in the frequency domain is studied. In addition, in order to investigate the efficiency of hydraulic mounts, the obtained results are compared to the corresponding results of engine on rubber mounts. The results show that considerable improvement in vibration and isolation of the engine and the body can be achieved in low frequency region. However, for high frequency region, behaviour of the engine on the hydraulic mounts is the same as on the rubber mounts.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p226.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p506" class="affilation"></a>Response Analysis of Ship Structures Subjected to a Cluster of Impulsive Excitations</h2>
<h3>Elena Ciappi, Daniele Dessi</h3>
<p class="affilation">INSEAN-Istituto Nazionale per Studi ed Esperienze di Architettura, Via Di vallerano 139, 00128 Rome, Italy</p>
<p><b>ABSTRACT</b><br>
In rough seas, the violent impact between the water and the hull, i.e., slamming, may determine relevant local and global effects on the ship’s structure, emphasized by the likely onset of hull vibrations, especially in innovative ship configurations characterized by lighter and flexible structures. Several models have been developed in last years both to analyze the single slamming event and its effect on the hull portion directly impacting the water surface (local effect) and on the whole ship (global effect), as well as probabilistic theories to study the occurrence of such slamming events. Both of these information, i.e., amplitude and frequency of the load cycles, are needed to evaluate the fatigue life of the structure. Though the random wave loads in operative conditions follow a Gaussian distribution, the slamming impacts show much more complex statistical features such as, for instance, the presence of clusters. On the basis of seakeeping experimental results performed on a segmented elastically scaled model of a fast monohull as well as on theoretical modeling of the slamming load, the global and the local ship response to these repeated impacts is investigated.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p506.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p504" class="affilation"></a>Exposure of Timber Truck Drivers to Whole-Body Vibration and Noise</h2>
<h3>Esko Sorainen, Marko Oksanen, Aki Vähänikkilä, Esko Rytkönen</h3>
<p class="affilation">Finnish Institute of Occupational Health, P.O, Box 93, FIN-70701 Kuopio, Finland</p>
<p><b>ABSTRACT</b><br>
The research focused on the exposure of timber truck drivers to whole-body vibration and noise. Sixteen timber trucks were chosen as the objects of the study. Vibration was recorded simultaneously from the seat and from the floor of the truck cabin, next to the seat fastening. Also, vibration was measured from the seat of the timber crane. The weighted one-third octave spectra of vibration were analyzed according to the 2002/44/EC “vibration directive” and the ISO 2631 (1997) standard. Seat vibration of the trucks exceeded the daily exposure action value of 0.5 m/s<sup>2</sup> in 63% of the cases. In the vertical direction, the seat vibration was the most powerful at frequencies between 1 and 12.5 Hz, and in the longitudinal and transverse directions at frequencies below 5 Hz. In the seats of the timber cranes, vibration exceeded the daily exposure limit value of 1.15 m/s<sup>2</sup> in some cases. The noise exposure of the drivers was below 80 dB(A), and inside the cabin of the truck, noise was the most powerful at frequencies between 63 and 2000 Hz.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p504.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p384" class="affilation"></a>Impact Property and Post Impact Vibration between Two Identical Spheres</h2>
<h3>Hirofumi Minamoto, Keisuke Saitoh, Shozo Kawamura</h3>
<p class="affilation">Toyohashi University of Technology Dept. of Mechanical Engineering, Hibarigaoka 1-1. Tempaku-cho, Toyohashi, 441-8580 Japan</p>
<p><b>ABSTRACT</b><br>
Contact and impact of spheres are fundamental and important problem in engineering. The severity of impact is generally characterized by the Coefficient of Restitution. However, deformed bodies after impact keep vibrating elastically. This paper deals with the direct central impact of two identical spheres and investigates the impact properties and post impact vibration. For this purpose, experiments and numerical simulations were carried out. The experimental and analytical results were compared and they matched quite well about their macro-mechanical quantities such as coefficient of restitution and contact time. On the post impact vibration, the effective value of the sphere center velocity increases with impact velocity but the frequency does not depend very much on the impact velocity.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p384.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p251" class="affilation"></a>Theoretical and Numerical Study on Hydroelastic Vibration of Plate for Various Bounded Fluid Field</h2>
<h3>Kuksu Kim, Suhyun Choi, Hyundong Cho</h3>
<p class="affilation">Dawoo shipbuilding & marine engineering co., ltd., 1, Aju-dong, Geoje-si, Gyeongsangnam-do, 656-714, Korea</p>
<p><b>ABSTRACT</b><br>
In this paper, a theoretical and numerical case study is carried out on the hydroelastic vibration of a rectangular plate in contact with various fluid fields. It is assumed that the tank wall is clamped along the plate edges. The fluid velocity potential is used for the simulation of the fluid domain and to obtain the added mass due to the wall vibration. The Assumed Mode method is utilized for the plate model and the hydrodynamic force is thus obtained. The proposed analytical approach was found to be in good agreement with the results of a well-known commercial three-dimensional finite element program. In addition, the natural frequencies are calculated and compared for rectangular plates in contact with various fluid fields. These include an infinite fluid, a finite fluid, a change in length of the finite fluid, and various fluid contacting conditions.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p251.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p777" class="affilation"></a>Stationary Response of a Military Tracked Vehicle</h2>
<h3>M. K. Ravishankar, C. Sujatha</h3>
<p class="affilation">Machine Design Section, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600 036, India</p>
<p><b>ABSTRACT</b><br>
In this paper, stationary response of a ‘2+N’ (9) degree of freedom (dof) tracked vehicle model fitted with conventional torsion bar suspension system is investigated for ground excitations resulting from rough off-road terrain operations. The vehicle is assumed to be moving with constant velocity on a randomly profiled terrain which is modeled as a homogeneous random process, being the output of a linear first order shaping filter to white noise. The equivalent road wheel stiffness is computed taking into account the stiffness due to track pad and the spring rate due to track tension. The investigations are carried out considering different randomness of terrain profile and also different stiffness values for the suspension system. The comparison of hull bounce acceleration and hull pitch acceleration is made for different configurations of suspension system.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p777.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p640" class="affilation"></a>A Spectral Finite Element Model for Thin Plate Vibration</h2>
<h3>Mohammad Tawfik</h3>
<p class="affilation">Modeling and Simulation in Mechanics Department, German University in Cairo, Cairo, Egypt</p>
<p><b>ABSTRACT</b><br>
The finite element analysis of plate vibration has become one of the classical problems that received a lot of attention from the researchers through the past few decades. Different models were developed including the classical polynomial elements, the hierarchical finite element models, and most recently, the spectral finite element models. Developers of different models introduced there models and performed many studies to prove that the models were suitable and accurate with validations performed against analytical models, when available, and with other numerical models. In this study, the first plate spectral finite element model is presented with a generalized methodology for the derivation element matrices. Three different finite element models will be compared in the study of free vibration characteristics of an isotropic plate with different boundary conditions. The aim of the study is to point out the points of weakness and strength of each model and to emphasise the ease and interchangeability of the models. The models compared are a classical 3<sup>rd</sup> order/4-node element, a 7<sup>th</sup> order/ 16 node element, and the proposed spectral finite element model. The models were created using a symbolic manipulator, Mathematica® 4.1, in order to get the elements’ matrices in closed form to avoid the errors introduced by the numerical integration that is usually used in creating the element matrices. Results are then compared with those obtained using numerical integration performed by creating a similar code using MATLAB 6.1.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p640.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p275" class="affilation"></a>Stochastic and Chaotic Analysis of Subharmonic Response of a Shallow Cable</h2>
<h3>S.R.K. Nielsen, J.W. Stærdahl</h3>
<p class="affilation">Department of Civil Engineering, Aalborg University, 9000 Aalborg, Denmark</p>
<p><b>ABSTRACT</b><br>
The paper deals with the subharmonic response of a shallow cable due to random chord length variations, caused by time varying motions of the support points of the cable. Under deterministic harmonic support point motions the stable subharmonic motion of order 2 consists of a harmonically varying component in the equilibrium plane and a large subharmonic out-of-plane component with a fixed phase lag producing a trajectory of the midpoint with a shape like the symbol used for infinity. A more realistic excitation is obtained by replacing the harmonic chord length variation by a narrow-banded process with the same variance and centre frequency. In this case a very different response pattern is observed even for a very small band width of the excitation process. The phase between the in- and out-of-plane displacements is no longer locked at a fixed value, causing the trajectory to rotate slowly around the chord line. As a consequence a substantial in-plane subharmonic response component is brought forward. Further, the time-varying amplitudes of the elongation variations tend to enhance chaotic behaviour of the response, which is detectable via extreme sensitivity on the initial conditions or via the sign of a numerical calculated Lyapunov exponent. The dependence of these findings on the specific stochastic modelling is investigated by analysing two chord elongation processes with almost identical auto-spectral densities, i.e. the statistical second moment properties of the processes are almost identical, whereas higher order moments differ significantly. In one case, the chord elongation is modelled as a filtration of a Gaussian white noise through a linear second order differential filter. The Gaussian output process has realizations with slowly varying phases and amplitudes slowly varying around the amplitude of the comparable harmonic excitation. In the other case the excitation process is modelled by a harmonic zero time-lag transformation of a Wiener process. All realizations have constant amplitudes equal to the purely harmonic excitation, but with a slowly varying phases. The two stochastic models provide qualitatively and quantitatively identical results. The conclusion is that the chaotic response caused by stochastic excitation mainly is due to time variation of the phases, whereas the amplitude variations are of minor importance.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p275.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p285" class="affilation"></a>Comfort Analysis of Lightweight Floor System</h2>
<h3>Sander Zegers, Frans van Herwijnen</h3>
<p class="affilation">Faculty of Architecture, Building and Planning, Department of Structural Design and Construction Technology, Technical University of Eindhoven, 5600 MB, The Netherlands </p>
<p><b>ABSTRACT</b><br>
During the past 60 years, floor systems used in housing and office-buildings in the Netherlands were mostly made of concrete or other similar materials. These floor systems, which can be characterized as heavy, normally posed little problems concerning vibrations. In recent years, in light of sustainable construction methods, there has been a trend to reduce the use of materials and thus build lighter. In addition, building-users nowadays are more critical with regard to the comfort of the building. Light-weight floor structures are often found to be susceptible to unacceptable vibrations. The vibrations are caused by dynamic actions such as persons walking or washing machines vibrating. If one of the natural frequencies of the floor system, usually the first natural frequency, is close to the frequency of these actions, problems occur. Besides the natural frequency other properties influence the perception of a lightweight floor system such as damping. This paper describes the structural parameters that influence vibration comfort. A quality measure is used to compare the measures, based on the velocity of the structure subject to vibration, which includes human sensitivity for vibration of different frequency. A detailed study will be presented on the effect of these measures and guidelines on practical application of the results are given. It will be shown that mass has no influence on the comfort of a beam.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p285.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p317" class="affilation"></a>Minimisation of Noise and Vibration Level from a Steel Panel</h2>
<h3>A. Shen, R. B. Randall</h3>
<p class="affilation">School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney, NSW 2052, Australia</p>
<p><b>ABSTRACT</b><br>
This work is part of a project to minimise the noise radiated from the casing of a constant speed gearbox by optimizing the positioning of stiffening ribs so as to create a “dead band” around the fixed gearmesh frequencies and their harmonics. Experimental studies were carried out on a baffled rectangular plate where a number of equally spaced stiffeners were attached, having been designed to minimize the radiation in a band around each of two harmonics of a simulated “gearmesh frequency”. The band was made wide enough to allow for errors in the model updating process and for variations between different realizations of the “same” stiffened plate. The properties of epoxy joints and elastic supports were identified and were applied in the subsequent model updating process. A good agreement between the numerical and experimental modal models was achieved. Frequency response functions were synthesised from the updated FE model in terms of natural frequencies and mode shapes. A pseudo-inverse method was used to identify the two forcing functions acting on the plate (before modification) which in turn were used to stimulate the updated FE model. The resulting vibratory and acoustic responses from the experiment confirmed the validity of the optimisation proposed by numerical simulation. The optimal stiffener layout resulted in ‘troughs’ in the vibration and acoustic levels within the frequency bands of interest for the original plate.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p317.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p495" class="affilation"></a>How to Predict the Vibration Effect Due to Machine Operation on its Surroundings</h2>
<h3>Alexandre Augusto Simões (1), Márcio Tadeu de Almeida (2), Fabiano Ribeiro do Vale Almeida (2)</h3>
<p class="affilation">(1) Department of Mechanical Engineering, UNIS Av. Cel. José Alves, 256, Vila Pinto, Brazil (2) Department of Mechanical Engineering, Federal University of Itajubá, Av. BPS, 1303, Brazil</p>
<p><b>ABSTRACT</b><br>
The satisfactory performance of a machine is concerned with its installation, i.e., with a well designed foundation and soil investigation. The vibration amplitude of the machine foundation system must be kept under permissible values generally specified by the machine’s manufacturers and natural frequencies must be determined to avoid resonance. There may be situations when amplitudes of the machine may be within the acceptable limits for satisfactory machine operation but the vibrations may affect other machines around, be harmful to adjacent structures and precision equipment and annoying to persons. Here in will be shown how to predict in a simple way the effect of the vibration due to the machine operation on its surroundings considering the foundation as a vibration source on the surface of an elastic medium.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p495.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p188" class="affilation"></a>Closed-Loop Feedback Model of Chatter in a Shaping Operation</h2>
<h3>Ayman El-Badawy (1), Tarek Nasr El-Deen (2)</h3>
<p class="affilation">(1) Deaprtment of Engineering Mechanics, The German University of Cairo, New Cairo City, Al-Tagamoa Al-Khames, Egypt (2) Department of Mechanical Engineering, Al-Azhar University, Nasr City, Cairo, Egypt</p>
<p><b>ABSTRACT</b><br>
The motivation of the work is twofold: (a) understand the physics behind regenerative chatter while presenting some experimental results to demonstrate the problem on a shaping operation, (b) develop a closed-loop time-delayed displacement feedback mathematical model that represent the chatter phenomenon. The model is then used to investigate certain combinations of cutting force and spindle speed that leads the feedback loop to become unstable. The root locus and bode-plot techniques are used to complement the physics with a control engineering perspective. Then, the stability lobe diagrams are compared with root locus and bode-plots of the system in order to validate the feedback model. Finally, instabilities due to structural and delay poles are identified and illustrated.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p188.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p180" class="affilation"></a>Analysis of High Longitudinal Vibration on a Diesel Generator Using Modern Analysis Tools</h2>
<h3>Ben Kidd, Stewart Kanev</h3>
<p class="affilation">ASC, Mersey Road, Osborne, SA 5017, Australia</p>
<p><b>ABSTRACT</b><br>
The tools used for vibration analysis have improved radically over the last few decades. However design for low vibration is still based on the principle of keeping the frequencies of dynamic forcing functions well removed from those of structural resonances. Exploration of this age old issue in a modern vibration analysis context is undertaken, using an example of high longitudinal vibration on diesel generators which power an Australian COLLINS CLASS Submarine. As the diesel and generators are supplied by different manufacturers, the result highlights the requirement to properly integrate machinery combinations from a perspective of design for low vibration.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p180.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p185" class="affilation"></a>River Pump Room Isolation from State Library</h2>
<h3>David Borgeaud (1), Michael Plumb (2)</h3>
<p class="affilation">(1) Environmental Resources Management Australia Pty Ltd Brisbane, QLD 4000, Australia (2) GP Embelton & Co. Pty Ltd, Melbourne, VIC 3134, Australia</p>
<p><b>ABSTRACT</b><br>
The Millennium Arts Project on the Brisbane River in Brisbane City is one of the largest State Government building projects undertaken in Queensland Australia for many years. Air-conditioning for the site is provided by the Central Energy Plant located in a dedicated building. This system receives its cooling water from a large river pump room located underground near the State Library of Queensland (Library) and Gallery of Modern Art (Gallery). The River Pump Room comprises 900kW of pumping capacity combining 3 submersible pumps and 3 plant room pumps. The initial design situated the pump room with a common wall to the Library which raised serious concerns regarding structure-borne noise and vibration. This paper discusses some of the design process and selection of a suitable system to minimise the structure-borne noise and vibration transmission. The design solution included structural separation of the Pump Room from the Library and Gallery, and vibration isolation of the elements of the River Pump Room system. Vibration isolation of the submerged pump sets presented various design challenges including: buoyancy effects of the tidal river channel system, potential bridging of the vibration isolation system by foreign objects (under base), provision of accurate horizontal positioning, and allowance for maintenance of pumps and motors. The buildings opened in December 2006, and the results of testing undertaken with the River Pump Room operating are described in the paper. The designed systems have achieved a successful outcome, and will allow staff and the public to quietly enjoy their new Library and Gallery for generations to come.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p185.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p775" class="affilation"></a>Updating an Elastodynamic Model of Gear Pumps to Helical Gear Prototypes</h2>
<h3>Emiliano Mucchi, Giorgio Dalpiaz, Simone Pizzotti</h3>
<p class="affilation">EnDIF- Engineering Department in Ferrara, Università degli Studi di Ferrara, Via Saragat, 1 44100 Ferrara, Italy</p>
<p><b>ABSTRACT</b><br>
A non-linear kineto-elastodynamic model for the dynamic analysis of external gear pumps for automotive applications has been presented and experimentally assessed in previous works. The model takes into account the most important phenomena involved in the operation of gear pumps with spur gears, there being gear meshing, pressure distribution around the gears and journal bearing behaviour. In this paper this model has been updated for the application to a new virtual pump prototype with helical gears in order to evaluate gear accelerations and dynamic forces before the hard prototype is available. The results of the simulations referring to the new pump are compared with the simulation results of the previous pump in terms of dynamic forces and gear accelerations. Finally, the model is also used in order to determine the causes of discontinuities in the dynamic forces and acceleration peaks.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p775.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p290" class="affilation"></a>Influence of Design and Operational Parameters on the Dynamic Behaviour of Gear Pumps</h2>
<h3>Emiliano Mucchi (1), Alessandro Rivola (2)</h3>
<p class="affilation">(1) EnDIF- Engineering Department in Ferrara, Università degli Studi di Ferrara, Via Saragat, 1 44100 Ferrara, Italy (2) DIEM, University of Bologna, Viale Risorgimento, 2 40136 Bologna, Italy</p>
<p><b>ABSTRACT</b><br>
This work concerns external gear pumps for automotive applications, which operate at high speed and low pressure and presents a sensitivity analysis about the influence of design and operational parameters on the pump dynamic behaviour. In previous work, a non-linear lumped-parameter kineto-elastodynamic model was developed, with the aim of including all the important effects, as well as to get a rather simple model. Two main sources of noise and vibration can be considered: pressure variation and gear meshing. The model has been validated by comparison with experimental vibration data, in a wide range of operational conditions and for different gear designs and several profile errors. This paper is focused on the analysis of the influence of the main design and operational parameters on the pump dynamic behaviour. In particular, the effect of operational pressure and speed, the influence of the clearance in the journal bearing and between tooth tip and pump case, and the effect of the dimension of the relief grooves in the bushes will be thoroughly discussed in the paper. Finally, the model could be a very useful and powerful tool in order to evaluate design improvements for noise and vibration reduction.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p290.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p292" class="affilation"></a>Which Are the Most Important Pressure Effects in Dynamic Analysis of Gear Pumps?</h2>
<h3>Emiliano Mucchi (1), Alfonso Fernandez del Rincon (2)</h3>
<p class="affilation">(1) Engineering Department in Ferrara, Università degli Studi di Ferrara, Via Saragat 1, I-44100 Ferrara, Italy (2) Department of Structural and Mechanical Engineering, University of Cantabria, Avda. De los Castros s/n 39005 Santander, Spain</p>
<p><b>ABSTRACT</b><br>
In previous works, the authors have presented a numerical model of the dynamic behaviour of an external gear pump for automotive applications. The model takes the most important phenomena involved in the operation of this kind of machine into account. The simulation results have shown that the variable meshing stiffness has a notable contribution on the dynamic behaviour of the pump but this is not as important as the pressure phenomena. As a consequence, the original model was modified with the aim of improving the calculation of pressure forces and torques in order to achieve a result that was closer to measured values. The new pressure formulation includes several phenomena not considered in the previous one, such as the pressure variations at input and output ports, as well as an accurate description of the trapped volume and its connections with high and low pressure chambers. In particular in this paper the relative effect of each considered pressure phenomenon will be discussed in detail, highlighting which are the most important ones, in order to develop a simple but accurate dynamic gear pump model. So, the improved model could be used in order to analyse the dynamic behaviour of the pump and to identify noise and vibration sources.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p292.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p26" class="affilation"></a>Modeling of the Sound Transmission Loss of Leaks and Openings</h2>
<h3>Franck Sgard (1,2), Hugues Nelisse (1), Noureddine Atalla (3)</h3>
<p class="affilation">(1) IRSST, Service de la recherche, 505 Bd de Maisonneuve, Montreal, QC H3A3C2, Canada (2) LASH/DGCB, Ecole Nationale des TPE, 2 Rue Maurice Audin, 69518 Vaulx-en-Velin Cedex, France (3) GAUS, Department of Mechanical Engineering, University of Sherbrooke, 2500 Bd de l’Université, Sherbrooke, QC J1K2R1, Canada</p>
<p><b>ABSTRACT</b><br>
The airborne sound transmission performance of structures may be strongly affected by the presence of apertures. These apertures might be designed on purpose to allow for the circulation of matter (machinery enclosures) or for the passage of wires and pipes through the structure (vehicles, buildings). They are then referred to as openings. They could also be unwanted or not part of the initial design due to bad assembly and/or mounting conditions. They are then called leaks. These two kinds of apertures differ by their size relative to the acoustic wavelength. To predict the insulating performance of a structure involving apertures, it is often required to know the oblique incidence or diffuse field sound transmission loss (TL) of the aperture. Numerous models exist for the normal incidence TL but rigorous models for oblique incidence and diffuse field excitations have rarely been considered. The diffuse field TL is usually obtained using a correction factor applied to the normal incidence TL which ranges from 0db to 5dB depending on the authors. The purpose of this paper is to propose a general efficient model based on the description of the field inside the aperture in terms of propagating and evanescent acoustic modes together with an efficient computation of modal radiation impedance matrices to predict the oblique incidence and diffuse field TL of rectangular and circular apertures of finite depth. The model is validated by comparison with existing experimental data and models. Numerical results illustrating the normal incidence, oblique incidence and diffuse field TL of apertures are then provided and the relationships between these indicators are discussed.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p26.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p740" class="affilation"></a>Noise Reduction of Personal Color Laser Printer</h2>
<h3>Hyoung Gil Choi (1), Jae Rack Choi (1), Sangyup Oh (1), Jong Woo Kim (2), Jin Young Jeon (2), Hyun Ki Cho (2)</h3>
<p class="affilation">(1) Mechatronics & Manufacturing Technology Center (2) Digital Printing Division, Samsung Electronics Co., Ltd., 416, Maetan-3dong, Yeongtong-gu, Suwon 443-742, Korea</p>
<p><b>ABSTRACT</b><br>
Noise in a personal color laser printer is known to have an important influence on customer’s acceptability. Noise incurred during printing may be perceived as being objectionable in quiet office environment even when the measured noise level is only moderate. To reduce printer noise, a good knowledge of the noise source mechanism is first required. In this paper major sources of printer noise are investigated by experimental approach. They are identified as drive noise, impact noise, and paper noise. Structural modifications are proposed to eliminate impact noise and paper noise by reducing the contact area. For the drive noise, it is proposed that the method of assembling motor-gear drive component into a main frame be changed. The proposed solutions are verified by mock-up test.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p740.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p25" class="affilation"></a>Investigate the Noise Problems of Ball Screws With and Without Cage</h2>
<h3>Jhy-Hong Wang, Bor-Shen Shu</h3>
<p class="affilation">Dept. of Power Mechanical Engineering, National Tsing-Hua University, Hsing-Chu, Taiwan</p>
<p><b>ABSTRACT</b><br>
The noise problems of ball screws with and without cage were investigated experimentally in this work. The noise sources of three types of ball screws without cage were first identified. The results show that the high frequency noise comes mainly from the friction between elements while the low frequency noise is mainly caused by the impact between balls and nut or screw. The noise sources of ball screws with cage were then identified. The results show that the cage can reduce the high frequency noise effectively only in some rotational speeds. Besides, the amount of reduction of noise by using the cage is different for different designs of ball screws.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p25.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p58" class="affilation"></a>Noise Control on Backhoe Loaders by Coherence and Intensity Techniques</h2>
<h3>K. Alper Yalçınkaya (1), Mehmet Çalışkan (2)</h3>
<p class="affilation">(1) HİDROMEK LTD. ŞTİ. 1. Organize Sanayi Bölgesi Osmanlı Cad. No:1, Sincan/ Ankara, Turkey (2) Department of Mechanical Engineering, Middle East Technical University, 06531 Ankara, Turkey</p>
<p><b>ABSTRACT</b><br>
The aim of this study is to control the interior and exterior noise emitted by the backhoe loader. A noise source identification methodology is developed throughout this work. This methodology consists of sound power level determination tests, spectral analyses of acquired noise data, coherent output power tests, and sound intensity measurements. Finite element analyses on engine hood and cabin cavity are performed to identify dynamic characteristics of the plates and the operator cabin. Results of these analyses are compared with the experimental results to identify the noise sources. Upon identification of the significant noise sources, proper noise control treatments are performed. Consequently, a required reduction of 2 dBA with reference to European Noise Directive 2000/14/EC is achieved in airborne sound power level of the backhoe loader. Cabin interior noise level at operator’s ear position also benefited from the improvements by the same amount i.e., 2 dBA.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p58.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p68" class="affilation"></a>Analysis of Vibratory Response and Noise Radiation of Engine Block Coupled with the Rotating Crankshaft and Gear Train System</h2>
<h3>Kazuhide Ohta (1), Takahiro Okimoto (1), Iwao Honda (2), Kazuhiro Yoshizumi (2)</h3>
<p class="affilation">(1) Graduate School of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, Japan (2) Mitsubishi Heavy Industries, Nagasaki R&D Center , 5-717-1 Fukahori-machi, Nagasaki, Japan</p>
<p><b>ABSTRACT</b><br>
This paper presents the theoretical procedure to predict the vibratory response and radiated noise of the engine block coupled with the rotating crankshaft and gear train shafts which drives the fuel injection pump and valve system. The exciting forces acting on the engine block and shaft system are combustion pressure, inertia forces of the moving parts, piston slap forces, fuel injection pressure and valve driving force and torque. Theoretical procedures consist of the following four steps; (1) Dynamic characteristics of the engine block and shafts are determined separately by FEM or experimental modal analysis. (2) Normal mode expansion technique is employed to derive the equation of motion of the total system in which rotating shafts with gear train are combined to the engine block by the oil film and contact stiffness. (3) The time histories of the vibratory response of the engine block and rotating shafts are calculated by the numerical integration technique. (4) Engine noise radiated from the engine block surface is evaluated using the spatially averaged mean squared velocity and acoustic radiation efficiencies of the engine block. This method is applied to estimate the effect of the backlash of the gear train on the engine block vibration and radiated noise.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p68.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p334" class="affilation"></a>Investigating the Effects of the Static Cutting Force on the Chatter Vibrations of Milling Process</h2>
<h3>M. Saeidifar, A. R. Ohadi</h3>
<p class="affilation">Mechanical Engineering Department, Amirkabir University of Technology (Tehran Polytechnic), Tehran, Hafez Ave. 424, Iran</p>
<p><b>ABSTRACT</b><br>
A chatter phenomenon is heavy vibration between work piece and tool which causes both a reduced product quality and rapid tool wear. In this paper, a 2-DOF milling process is considered with the symmetric parameters in the feed and normal directions. Then stability lobes diagram (SLD) is derived by the method presented by Altitas in order to find the specific combination of depth-of-cut and spindle-speed, which results in the maximum chatter-free material removal rate. Also the border between a stable cut (i.e. no chatter) and unstable cut (i.e. with chatter) is obtained from solving the time domain delay-differential equations (DDE) by means of the numerical method (4th order Runge-Kutta). The point of interest in this study is that the static part of the cutting force is not ignored and directional dynamic milling force coefficients are utilized in exact form. Finally, numerical results, experimental results from previous works and SLD have been compared. It is observed that the correlation between the numerical and experimental results is much better than the corresponding correlation between the SLD and experimental results.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p334.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p96" class="affilation"></a>Acoustical Treatment of Emergency Power Generator</h2>
<h3>M.Abd El Gawad Saif</h3>
<p class="affilation">Housing & Building National Research Center, Dokki, Giza, Egypt</p>
<p><b>ABSTRACT</b><br>
Noise pollution is one of the dangerous invisible pollutants, which has been blamed for everything from hypertension and learning difficulties, to hearing loss. So many international organizations label noise as a “real and present danger”. The best way to reduce noise is at the source of the noise: adjust or repair the source so it no longer produces (as much) noise. It’s also possible to alter the workplace environment to adequately compensate for the noise, for example, building sound barriers between workers and the noise source. This paper is a study to reduce noise level of emergency power generator at the source by using special acoustical treatment design which reduces noise levels by about 36 dB.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p96.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p422" class="affilation"></a>Numerical/Experimental Characterization of a Piezoelectric Driven Electromedical Device</h2>
<h3>Massimo Viscardi, Michele Iadevaia, Leonardo Lecce</h3>
<p class="affilation">Dept. of Aerospace Engineering , University of Naples “Federico II” Via Claudio, 21 - Naples , Italy</p>
<p><b>ABSTRACT</b><br>
The present work refers to the numerical/experimental characterisation of an electromedical device, based on piezo actuator technologies, used for dermacosmetic applications. Special focus was given to the fatigue related problems that have arisen during the operational life of the device, and which are related to the high frequency dynamic loads to which the device itself is subjected. Preliminary studies have indicated a recursive crack faults that characterize, the slim extremities of the devices (bar); previous test, also put in evidence, that the crack location generally lies along an operational deflection mode nodal line. To better understand the physical phenomena at the basis of this circumstance and to design specific solutions to overcome this problem, a set of numerical and experimental activities have been planned and performed. The set of activities may be summarised as follow: <ul> <li>FEM modelling of the bar devices and extraction of eigen-frequencies and modes</li> <li>FEM modelling of forced response to the piezoelectric excitation and the calculation of fatigue parameters</li> <li>Experimental vibrational analysis by the use of scanning laser technique; operational mode shapes extraction</li> </ul> It should be noted that the use of the laser technique has permitted the identification of the high frequency modes and has avoided problems which could arise with accelerometers due to their dimensions, mass loading effects and limited frequency response. The results of this program have shown good agreement between the experimental and numerical values and have identified also the significant influence of the boundary conditions on the life on the bar. The study has also identified some possible solutions including the modification of the material, change of shape, or the use of a different soldering technology.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p422.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p525" class="affilation"></a>Structure-Borne Noise Generated by Vacuum Cleaner Suction Units</h2>
<h3>Mirko Čudina, Jurij Prezelj</h3>
<p class="affilation">University of Ljubljana, Faculty of Mechanical Engineering, Aškerčeva 6, 1000 Ljubljana, Slovenia</p>
<p><b>ABSTRACT</b><br>
Noise emitted by a vacuum cleaner suction unit consists of airborne and structure-borne noise. The airborne noise is generated mainly by the turbo blower and the structure-borne noise is generated mainly by the driving electric motor. Structure-borne noise is an audible sound that is structural in origin, i.e., it begins as vibration. Basically, each substructure of a suction unit has one of the resonance frequencies and can affect the overall vibration behaviour. The normal mode of vibration of each part of the suction unit depends on its mechanical properties. The structure-borne noise depends on the suction unit design and on operating conditions. In this paper the effects of vibrations of the suction unit structure on the noise characteristics have been measured and analysed at the design and off-design operation. Measurement results have shown that contribution of structure-borne noise to the total sound pressure level becomes important at partial flow rates, especially when the rotating stall and surge in the turbo blower appear, and is relatively less important at higher flow rates and towards the free delivery. Among geometrical parameters, the stator of the turbo blower and electric motor, or metal shield if any, are main origins of the structure-borne noise. A vaned diffuser built-in the blower has the greatest effect on the structure-borne noise.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p525.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p128" class="affilation"></a>Optimization of Sound Insulation in the New Generation of Washing Machines</h2>
<h3>Nikola Holeček, Marjan Semprimožnik</h3>
<p class="affilation">Gorenje, d.d., SI 3503 Velenje, p.p. 107, Slovenia</p>
<p><b>ABSTRACT</b><br>
One of the most significant parameters of quality and functionality of washing machines is their noise level. Insulation is certainly the most important method for noise reduction and this is why most research has been dedicated to it. We also took into account the fact that cost limitations were necessary for achieving our target value with the cheapest insulation possible. Consequently, this is a presentation of experimental method of defining sound power and the procedure for the reduction of washing machine noise by the use of muffling materials. The noise level at various development stages was characterized by total sound power level dB, sound intensity, sound pressure level frequency spectra, and sound intensity vector analysis. By measuring sound intensity along all five radiation surfaces the places of the highest radiation were localised and insulation was created according to this. The noise at critical points was reduced and we achieved the recommended values for sound power level.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p128.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p239" class="affilation"></a>An Accurate Method of Knock Detection Using Wavelet Transform for Spark-Ignition (SI) Engine</h2>
<h3>Nobuo Kurihara (1), Junichi Suzuki (1), Yuuya Shirayama (1), Jonathan Borg (2), Shigeru Oho (2)</h3>
<p class="affilation">(1) Hachinohe Institute of Technology, Hachinohe, AOMORI 031-8501, Japan (2) Hitachi America Ltd., Farmington Hills, MI 48335, USA</p>
<p><b>ABSTRACT</b><br>
This study examined the application of wavelet transforms to signal processing to improve the reliability of knock detection. It was expected that this method would make it possible not only to keep track of continuous knock vibrations, but also to detect vibrations occurring and disappearing instantaneously. For this the scale-spectrum comparison method was proposed as the method of knock detection. This method focuses on the components of resonant vibration that are specific to the engine, and compares their scale power spectra with each other in real time. A 4-cycle gasoline engine was used for the experiment. Cylinder pressure sensors and a vibration sensor were attached, and a comparative examination of the knock detection performance of the two signal processing methods, the conventional Fourier transform method and the proposed scale-spectrum comparison method, was carried out. Data over the whole operating range of the engine was obtained, and the data showed that it was possible to reduce both errors and mistakes as compared with the conventional method.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p239.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p225" class="affilation"></a>Active Control of Chatter Vibrations in a Turning Process Using an Adaptive FXLMS Algorithm</h2>
<h3>O. R. Hashemi, A. R. Ohadi</h3>
<p class="affilation">Mechanical Engineering Department, Amirkabir University of Technology (Tehran Polytechnic), Tehran, Hafez Ave. 424, Iran</p>
<p><b>ABSTRACT</b><br>
In this paper a 2-DOF lumped mass model is used for dynamic modelling of a turning process. The cutting forces are modelled using predictive machining theory based on the Merchant cutting force model. Cutting parameters such as shear angle are calculated using experimental relations. Variation of cutting angles is also considered. Regarding the governing delayed differential equations, the model is simulated in the time domain using a Matlab/Simulink program. There is a good agreement between simulation results and the simulated and experimental results obtained by Xiao et al. Then, chatter vibration is suppressed using a single channel feedback FXLMS control method. The adaptive FIR filter generates proper canceller signals for the piezoactuators to reduce tool vibrations. The control method has the advantage of considering the statistical vibration of the cutting process that would be rarely considered in other active control methods. By using adaptive filters, it is possible for the controller to always be in the optimum condition by changing the FIR filter coefficients based on measured error signals. A significant reduction in vibration amplitude of the tool is achieved by using this active vibration control method. The response of the controller is observed for different actuator positioning. In addition, the performance of this control method is evaluated in the presence of disturbances in the vibration signals.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p225.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p439" class="affilation"></a>Dynamics of Piezoceramics-Based Mass and Force Actuators for Rotating Machines</h2>
<h3>Peter Sloetjes, Andre de Boer, Peter van der Hoogt</h3>
<p class="affilation">University of Twente, Faculty of Engineering Technology, Applied Mechanics Section, Drienerlolaan 5, 7500AE, Enschede, The Netherlands</p>
<p><b>ABSTRACT</b><br>
In the past decade, it has become more and more common to install active vibration control devices on rotating systems like grinding machines, tooling centers, industrial fans and drive shafts. In the present research, two innovative actuation concepts for such devices are evaluated. The first device is a force actuator based on piezoceramic fibers, which has a low power consumption and high dynamic range. The second device is a mass redistribution actuator based on two piezoelectric ultrasonic motors, which is smaller and faster than conventional electromagnetic devices. At the basis of the analysis are rotor dynamic finite element models including actuators, sensors and feedback controllers. In simulations and experiments with device one, feedback control and scheduled feedforward control are considered. It is shown experimentally that the unbalance response at a critical speed can be reduced by some 97%. In experiments with device two, the positioning speed is determined.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p439.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p564" class="affilation"></a>The Design of Motor Brackets for the Reduction of Structure-Borne Noise in Package Air-Conditioners</h2>
<h3>Sang-Gil Park (1), Hyun-Jin Sim , Hae-Jin Lee (1), You-Yub Lee (2), Jae-Eung Oh (3)</h3>
<p class="affilation">(1) Department of Mechanical Engineering, Hanyang University, Haengdang-Dong 17, Sungdong-Gu, Seoul, Korea (2) Division of Automotive & Mechnical Eng, Howon University, 727, Wolha, Impi, Gunsan, Jeonbuk, Korea (3) School of Mechanical Engineering, Hanyang University, Haengdang-Dong 17, Sungdong-Gu, Seoul, Korea</p>
<p><b>ABSTRACT</b><br>
As economic power increases and customer demand becomes more difficult to satisfy, noise and vibration will be the most important factors in determining product quality. With a sudden increase in demand, product quality and noise are becoming decisive factors in determining whether a product is purchased. Consequently, manufactures are investing significant money and research to reduce the unpleasantness of noise and vibration. In addition, they are distinguishing their products by aggressively advertising their low-noise output. For these reasons, the demand for a silent indoor air-conditioner has made relevant research essential to product development. In this study, noise and vibration are visualized in space and frequency domains by using experimental methods such as operational deflection shape (ODS), modal testing, and sound intensity. Also, the location of the noise source and its characteristics are analyzed from an acoustical point of view to reduce the structure-borne noise that comes from the fan motor, and a pertinent control method is suggested. Furthermore, the most suitable shape of the motor bracket is suggested by applying FEM and DOE (Design of experiments) from the point of view of noise and vibration.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p564.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p408" class="affilation"></a>A Study of the Design of a Cantilever Type Multi-D.O.F. Dynamic Vibration Absorber for Micro Machine Tools</h2>
<h3>Sung-Hyun Jang (1), Sung-Min Kim (1), Shil-Geun Kim (1), Young-Hyu Choi (1), Jong-Kwon Park (2)</h3>
<p class="affilation">(1) Dept. of Mechanical Design & Manufacturing Engineering, Changwon National University, Changwon, Gyeongnam, South Korea (2) Korea Institute of Machinery & Materials, Daejeon, South Korea</p>
<p><b>ABSTRACT</b><br>
This paper presents a study of the design of a cantilever type multi-d.o.f. damper, which can be used on micro machine tools, to reduce resonant vibrations. The proposed micro dynamic damper consists of three cantilever beams and a rigid body suspended from the cantilever beam. For dynamic analysis and design synthesis, a vibrating system with the dynamic damper is mathematically modeled as a lumped parameter model, in which cantilever beams and the rigid body are idealized as springs and a mass respectively. The natural frequencies and harmonic response of the mathematical model are obtained by using modal analysis theory. From the results, the spring constants and mass of the dynamic damper which reduce the resonant vibrations of the main system can be determined. A case study shows the proposed cantilever typed micro dynamic damper can successfully reduce resonant vibrations of the main machine, in the three different directions, at specified resonant frequencies.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p408.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p261" class="affilation"></a>Identification of Machine Tool Chatter for Milling Operations with Runout</h2>
<h3>Tamas Insperger (1), Brian P. Mann (2), Tobias Surmann (3), Gabor Stepan (1)</h3>
<p class="affilation">(1) Department of Applied Mechanics, Budapest University of Technology and Economics, 1111 Budapest, Hungary (2) Department of Mechanical and Aerospace Engineering, University of Missouri-Columbia, Columbia, MO 65211, USA (3) Department of Machining Technology, University of Dortmund, 44369 Dortmund, Germany</p>
<p><b>ABSTRACT</b><br>
Detection of undesired machine tool vibrations during milling operations is an important task for manufacturing engineers. Monitoring of frequency spectra is an efficient tool of chatter detection since these spectra usually have a clear, systematic structure. However, for some special cases, stability of the cutting process cannot be assessed based purely on the frequency spectra due to the disturbing effect of the runout of the tool. In this paper, it is shown that the stability of these cases can be assessed by the analysis of the vibration signal instead of the frequency spectra. Theoretical results are confirmed by experimental cutting tests.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p261.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p336" class="affilation"></a>Investigation of Torsional Vibration Characteristics of Marine Diesel Engine Crankshaft System</h2>
<h3>Won-Hyun Kim, Soo-Mok Lee</h3>
<p class="affilation">Hyundai Maritime Research Institute, Hyundai Heavy Industries Co., Ltd., 1 Cheonha-Dong, Dong-ku, Ulsan, 682-792, Korea</p>
<p><b>ABSTRACT</b><br>
Evaluation of the torsional vibration characteristics of a crankshaft system is indispensable to the development of marine diesel engines. It influences the selection or decision about shafting components such as the flywheel, torsional damper, generator and even modification of the crankshaft itself. In this paper, experimental and analytical investigations of torsional vibration were carried out for a newly developed marine diesel engine. The measurements were performed on various system changes e.g. engine with and without torsional damper, tuning wheel and coupling of dynamometer or generator. Based on the measurement results, analytical models were tuned to achieve better reliability. Meanwhile the sensitivity of parameters - inertia, stiffness and damping on the free vibration and torsional response-were assessed quantitatively and qualitatively. Dynamic stresses in the highly stressed area of the crankshaft were also measured under actual operating conditions with telemetry equipment. The safety factor against fatigue was evaluated with the measured stresses and compared with the analyzed ones and showed good agreement with each other.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p336.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p116" class="affilation"></a>Shock Analysis of Propulsion Shaft of the Ship with Consideration of the Oil Film Force</h2>
<h3>Xiaoping Zhu, Qi Feng</h3>
<p class="affilation">School of Aerospace Engineering and Applied Mechanics, Tongji University, Shanghai, 200092, China</p>
<p><b>ABSTRACT</b><br>
The propulsion shaft of a ship is investigated. It is modelled by the Dynamics of an Elastic Body Method. Oil film forces are obtained by the Average Eigenvalue Method. The effect of rotation velocity and oil film force on the response of the shaft under shock is considered; the flexibility of the bearing housing is also considered. The equations of motion of the main propulsion shaft of the ship are derived; they are solved using classical theory. In the end, the Runge-Kutta Method is used to do the numerical simulation. Results show that oil film bearings have a good effect on the alleviation of the vibration of the shaft.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p116.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p29" class="affilation"></a>Powered Seat Adjuster Noise Characteristics and its Psychoacoustics Assessment</h2>
<h3>Xu Wang (1), Aleksandar Subic (1), Jason Miller (2)</h3>
<p class="affilation">(1) School of Aerospace, Mechanical and Manufacturing Engineering, RMIT University, Bundoora East, Melbourne, VIC 3083, Australia (2) Futuris Automotive Interiors (Australia) Pty Ltd, 80 Turner Street, Port Melbourne, Victoria 3207, Australia</p>
<p><b>ABSTRACT</b><br>
In order to improve the noise performance for the seat adjuster mechanism, noise and vibration measurements were conducted in both European and Australian cars for six and eight modes of the seat adjustment operations on the driver’s seat. The six modes of the driver’s seat operations are: both up for the front and rear seat ends, both down for the front and rear seat ends, front seat end up, front seat end down, rear seat end up and rear seat end down. The eight modes of the seat operations are: forward, backward, both up for the front and rear seat ends, both down for the front and rear seat ends, front seat end up, front seat end down, rear seat end up and rear seat end down. The noise and vibration levels, sound quality and the root causes for the noise problems have been analysed and discussed for the six and eight modes of the seat adjustment operations. The noise characteristics have been identified; the psychoacoustic parameters have been used to quantify the sound quality of the seat adjuster and the assessment results have been found to match well with subjective evaluation results.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p29.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p587" class="affilation"></a>Research on Dual-Shaker Sine Vibration Control</h2>
<h3>Yaoqi Feng, Hanping Qiu</h3>
<p class="affilation">Dynamic Test Laboratory, BISEE, China Academy of Space Technology (CAST), China</p>
<p><b>ABSTRACT</b><br>
This paper analyses and sums up the existing problems which occur in dual-shaker sine vibration testing of large spacecraft structures by using the vibration level controller and the phase controller to control separately the level and phase of two shakers. From this basis, a new method which consists of controlling simultaneously the vibration level and phase of two shakers is proposed for dual-shaker sine vibration control. In the paper, the techniques used to generate the two driving signals, to acquire and process the response data and phase signal, and to control the vibration level and phase of two shakers are described in details. Finally, the paper presents briefly the test results obtained by using the new control method to carry out the sine vibration testing by means of two small shakers, and the test results obtained illustrate that the proposed method can be used for dual-shaker sine vibration testing.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p587.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p757" class="affilation"></a>Reduction of Noise and Vibration of Front Loading Washing Machine in Spin-Cycle</h2>
<h3>Young-hyun Kim (1), Seoung-jin Seo (2), Hong-seok Ko (1), Hyung-gyoon Kim (1)</h3>
<p class="affilation">(1) Samsung Electronics, Digital Appliance Washing Machine R&D team, 416, Maetan-3Dong, Paldal-Gu, Suwon, Korea (2) Samsung Electronics, Technology Strategy Office Mechanical Design Automation Infra Group, 416, Maetan-3Dong, Paldal-Gu, Suwon, Korea</p>
<p><b>ABSTRACT</b><br>
Water is pumped out from the washing machine during spin cycle by drain pump, which is the cause of noise and vibration. These noise and vibration may be characterized by three main sources. First is the fluid force caused by the rotating blade hitting the surface of the water. Second is the force created by the unbalance in the rotating structure and third is the electrical force caused by motor. The objective of this paper is to minimize theses forces transferring from drain pump to washing machine. These forces were characterized using multi-physics analysis and verified them through vibration and fluid experiments. Also design sensitivity analysis for optimizing drain pump mount position and properties were conducted. The suggested optimal design method for mounting the drain pump was tested and improvements were confirmed.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p757.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p394" class="affilation"></a>Vibro-Acoustic Characterisation of a D.I. Diesel Engine by the Use of the Scanning Laser Vibrometer Technique</h2>
<h3>Daniela Siano</h3>
<p class="affilation">Istituto Motori - CNR, Via Marconi, 8 Naples, 80125, Italy</p>
<p><b>ABSTRACT</b><br>
The objective of this work is represented by a laser vibrometer application on a diesel engine for the identification of noise sources associated with its structural vibration. The first investigation has been concentrated on the possibility to identify as well as quantify the structural noise emissions of a direct injection diesel engine, used mainly for agricultural application as well as small off-road vehicles. In fact, the quantity of noise emitted by the structure represents a large part of overall noise level. The structural noise is directly, in fact, associated with the surface velocity of the engine structure and/or of its components and for this reason is very important to correlate the vibration and acoustic analyses. Through the use of a scanner laser vibrometer (mod. PSV400 Polytec), the vibration maps have been determined of the four accessible investigated surfaces around the engine (according to the standard ISO 3744). In particular, a set of 48 scanning data have been executed: one scanning for each surface of the engine and for 6 different engine speeds in motored and firing operating conditions. The motored condition has been investigated for different engine speeds in order to quantify the mechanical noise associated with the rotating components and finally to compare with the overall noise in the firing condition. Vibration analysis has been conducted in the investigated frequency range 1 Hz - 4000 Hz. In the last step of the work the vibration data coming from the laser scanning vibrometer have been compared with the acoustic data previously determined through an intensity analysis in order to firstly identify the noise sources and secondly to better understand the nature of the noise, which represents an important information for future optimization.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p394.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p247" class="affilation"></a>Nonlinear Effects in Airborne Sound Insulation Measurement</h2>
<h3>Doheon Lee, Densil Cabrera</h3>
<p class="affilation">Faculty of Architecture, Design and Planning, University of Sydney, NSW 2006, Australia</p>
<p><b>ABSTRACT</b><br>
The level difference (D) between a source and receiving room should be independent of the source’s sound power level if the acoustic system (including the building fabric) is linear and time-invariant (LTI) and the signal to noise ratio is adequate. Furthermore, various measurement signal types such as white noise, maximum length sequence, and swept sinusoid (to derive impulse responses) should also yield equivalent results in an LTI system with adequate signal to noise ratio. This study investigates the presence of non-linear effects in a case study of a real building by measuring D using a range of sound power levels and signal types. This follows on from previous work which suggested that substantial non-linearities could affect measurements in the very low frequency range (20-100 Hz), so the present study includes these very low frequencies, but also investigates the usual frequency range for airborne sound insulation measurement. In this study, fixed source and receiver positions were used to measure D (without spatial averaging) between a pair of adjacent rooms. Three test signals were used: maximum length sequence (used both as white noise, and deconvolved to impulse responses), a linear swept sinusoid and a logarithmic swept sinusoid (deconvolved to impulse responses).</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p247.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p498" class="affilation"></a>Experimental Comparison of PU Probes and Microphone Arrays Used in Impulse Acoustic Holography</h2>
<h3>François Ollivier (1), Sylvie Le Moyne (1), Christophe Picard (2)</h3>
<p class="affilation">(1) Institut d’Alembert- Université Pierre et Marie Curie - Paris 6, Paris, France (2) PSA Peugeot Citroën - Aérodynamique Aéroacoustique Aérothermique, Vélizy, France</p>
<p><b>ABSTRACT</b><br>
The aim of this work is to evaluate the gain of information provided by pressure-velocity probes as compared to microphones in near field acoustic holography (NAH). The acoustic field under study is the near acoustic impulse response of a thin plate submitted to a shock. Both a 4 PU probes array and a 120 microphones array are used to sweep the field of interest according to a fine grid. Finally, three different wide band acoustic near fields are obtained: the normal component of the acoustic velocity, and two different measures of the acoustic pressure. Near field acoustic holography is thereafter performed with the three measured quantities, each of which provide a reconstruction of the source normal velocity field. Along these processes, the fields and their transformations (K-space spectra and reconstructed vibration source fields) are compared. The normal velocity source distribution is also directly measured with a laser vibrometer. This distribution is considered as a reference for the evaluation of the different NAH processes by means of correlation coefficients.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p498.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p212" class="affilation"></a>Analysis and Performance Monitoring of Electro Acoustic Systems</h2>
<h3>Frantisek Kadlec</h3>
<p class="affilation">Faculty of Electrical Engineering, Czech Technical University in Prague, Technicka 2, 166 27 Prague, Czech Republic</p>
<p><b>ABSTRACT</b><br>
The analysis of acoustic and electro-acoustic systems includes measurement of their transfer functions, determination of their behavior from the non-linear point of view and impact of external noises on their performance. The analysis and performance monitoring may be performed by exciting the system under test by either harmonic signals, random signals or by impulse methods. For analysis of electro-acoustic systems we concentrated on a method using swept harmonic signals. This method uses driving the system under test by logarithmically swept signal and recording the system response to the test signal. A so-called “inversion filter” is derived from the exciting signal. By convolution of the system response with this inversion filter we obtain the impulse response of the system under test. During a large signal excitation or even overload of electro-acoustic systems, a non-linear distortion may take place. This phenomenon can be analyzed from responses obtained by this method. By appropriate selection of driving signal parameters we can determine the individual distorting components. The method proved especially suitable for monitoring of multichannel systems, where it is possible to observe performance of individual channels as well as their mutual interaction, crosstalk etc.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p212.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p729" class="affilation"></a>A Method for Optimal Reconstruction of Velocity Response Using Experimental Displacement and Acceleration Signals</h2>
<h3>Gareth J. Bennett (1), José Antunes (2), John A. Fitzpatrick (1), Vincent Debut (2)</h3>
<p class="affilation">(1) Department of Mechanical and Manufacturing Engineering, Parsons Building, Trinity College Dublin, Dublin 2, Ireland (2) Applied Dynamics Laboratory Instituto Tecnológico e Nuclear ITN/ADL, 2686 Sacavem, Portugal</p>
<p><b>ABSTRACT</b><br>
An algorithm is developed which takes advantage of the positive characteristics of integration and differentiation operations which can produce an optimal time-domain estimate of a velocity signal when a displacement and an acceleration signal are measurable. Simulations are carried out with Matlab where synthetic data is generated through solving the equations of motion of a multi-degree of freedom vibrating system. The velocity optimisation technique for velocity estimation is applied to the acceleration and displacement signals and the result is compared to the true velocity signal. A parametric analysis is carried out on the technique, as a function of extraneous noise on the simulated signals, as well as the integration and differentiation operator employed. Based on the results of the simulations, an experiment is performed where a reconstructed velocity is compared to a velocity signal measured directly using a laser vibrometer.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p729.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p769" class="affilation"></a>An On-Line Monitoring Technique for a Pipe Thinning</h2>
<h3>Jin-Ho Park, Doo-Byung Yoon, Young-Chul Choi</h3>
<p class="affilation">Advanced Condition Monitoring & Diagnostics Laboratory, Korea Atomic Energy Research Institute, 150-1 Deokjin-Dong Yuseong-Gu, Daejeon City, Korea</p>
<p><b>ABSTRACT</b><br>
A new novel technique for the pipe thinning is introduced, which is one of the major issues regarding the structural fracture of pipes in nuclear power plant. The method is to inspect a large area of a piping system at a time on an on-line basis monitoring. The basic idea came from the fact that the group velocity of an impact wave is dependent on a wall thickness of the piping. That is, if the group velocity is measured, the wall thickness can easily be estimated. To obtain a group velocity, a time-frequency analysis is utilized. This is because an arrival time difference between the flexural waves can be measured easier in time-frequency domain than a time domain. To test the performance of this technique, experiments have been performed for a plate and elbow type pipe. Results show that the proposed technique is effective for monitoring the pipe thinning at an early stage.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p769.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p810" class="affilation"></a>Experimental Identification of the Transfer Matrix of the Muffler</h2>
<h3>Ke Liu (1), Tao Feng (2), Rui Wu (1), Qijun Zhou (1), Lijian Ye (1)</h3>
<p class="affilation">(1) Institute of Acoustics, Chinese Academy of Sciences, P. O. X 2712 Beijing 100080 China (2) Beijing Technology and Business University, NO.11, Fu-cheng-lu Road, Beijing, China</p>
<p><b>ABSTRACT</b><br>
The transfer matrix, which is independent with the boundary conditions, is one of the most important parameters of the muffler. An experimental identification method obtaining the transfer matrix based on the least square method (LSM) is developed here. The quantitative relationship between the parameters in the transfer matrix and the sound pressure measured at the certain position in experimental system is researched. A muffler and a measurement pipe system are designed and established to validate the identification method. The experimental procedures according to the identification theory are also referred. The experimental identification results match the analysed ones very well.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p810.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p196" class="affilation"></a>Effect of Artificial Mouth Size on Speech Transmission Index</h2>
<h3>Ken Stewart, Densil Cabrera</h3>
<p class="affilation">Faculty of Architecture, Design and Planning, University of Sydney, Sydney, NSW 2006, Australia</p>
<p><b>ABSTRACT</b><br>
For this study a head and torso simulator was constructed with a variable mouth size. Directivity measurements confirmed that a larger mouth size yields a more directional radiation pattern. The effect of the mouth size on speech transmission index (STI) measurements was investigated for various azimuth angles around the simulator and various room acoustical contexts. In some circumstances source directivity does affect STI values.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p196.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p291" class="affilation"></a>Comparison of Speech Measurements in a Diffuse Space</h2>
<h3>L. Gomez (1), C. Nestoras (2), S. Dance (2), S. Murano (1)</h3>
<p class="affilation">(1) Telent plc, Harbour Exchange Square, Docklands, London E14 9GE, UK (2) Acoustics Group, School of Engineering, London South Bank University, London SE1 0AA, UK</p>
<p><b>ABSTRACT</b><br>
An on-site experiment was undertaken in the ticket hall of London’s Heathrow Terminal 4 Underground station. The purpose of the investigation was to evaluate the speech intelligibility obtained from two distinct measuring systems characterized by their open-loop and closed-loop configurations. Previous acoustic measurements in the space of interest showed significant diffuse field characteristics. Two additional comparative analyses were also undertaken, contrasting intelligibility results between multi and single source as well as derived STI values against STI-PA meter readings. The station’s public address system (multi-source) and a single omni-directional source were utilized in turn for the tests. Both sound sources were driven by an amplified e-swept sine signal. Impulse response derived RT and STI parameters were obtained by using WinMLS and Dirac measuring and post-processing systems. WinMLS in closed loop mode requires long source and receiver cables, while Dirac in open loop mode reduces the requirement for hazardous cabling, particularly when the existing station’s PA system is used as a source, by employing a hand-held sound recording SLM as a receiver. Similar STI values were obtained for both open and closed loop systems. The close agreement in the STI values obtained from multi-source and single-source configurations suggested that both methods may be valid to excite an acoustic diffuse field space to measure speech intelligibility. STIPA readings were in agreement with derived STI values.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p291.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p41" class="affilation"></a>Investigation of Start-up Impact Characteristics of Liquid Rocket Engines</h2>
<h3>Li Feng, He Zexia, Bao Futing</h3>
<p class="affilation">Northwestern Polytechnical University, Xi’an, Shaanxi 710072, P.R.China</p>
<p><b>ABSTRACT</b><br>
The wavelet analysis is applied to process start-up impact signals of liquid rocket engines in this paper. With good localization in time and frequency domains, the wavelet analysis can focus on any desired parts of the object signals and is very suitable for analyzing strong time-dependant or non-stable signals. By analyzing the time-energy charts, the frequency-energy charts and the time-frequency-energy charts at the same time, fine difference in time sequence and frequency of different impact signals is checked. The possible factors affecting the impact level is analyzed then. The study may be helpful for fault diagnostics of the start up of LRE.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p41.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p413" class="affilation"></a>A Numerical Study on Practical Measurement Method of Vibration Intensity in a Plate with Standing Wave</h2>
<h3>Manabu Yahara, Taito Ogushi, Masato Mikami, Naoya Kojima</h3>
<p class="affilation">Graduate School of Science and Engineering, Yamaguchi University, 2-16-1 Tokiwadai, Ube, Yamaguchi, 755-8611, Japan</p>
<p><b>ABSTRACT</b><br>
It is important to gain information about the source of excitation and the resulting transmission paths when dealing with the response of actual structures to impacts. The Vibration Intensity (VI) method is an effective way of acquiring this information. It is also important to be able to establish VI even in the presence of background noise, such as that due to standing waves. A simplified VI formula was applied to practical VI measurement methods on actual structures. However the adoption of a simplified VI formula results in errors under certain conditions. Thus a simplified VI method was compared with the standard approach to investigate the vibration field of a plate subjected to an impulse and, simultaneously, a predominant standing wave. The VI direction angle error, with the simplification, was less than 30 degrees anywhere and was less than 10 degrees at loop points. Next, the results with and without predominant standing wave were compared for the various amplitude ratios, and the limit of detection of the impulse response were discussed. The VI direction angle errors decreased with increasing the amplitude ratios.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p413.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p624" class="affilation"></a>Extraction of Wavenumbers and Amplitudes from Plate Vibration Measurements</h2>
<h3>Michael Skeen, Nicole Kessissoglou</h3>
<p class="affilation">School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney, NSW 2052, Australia</p>
<p><b>ABSTRACT</b><br>
This paper introduces a technique for extracting the wavenumbers and displacement amplitudes from experimental vibration measurements of a plate simply supported along two parallel edges. The displacement field at any location on the plate can be predicted from the extracted wavenumber and amplitudes used in conjunction with an analytical waveguidebased model. Using simply supported boundary conditions along two parallel edges of the plate, the structural response can be described by a combination of a modal and travelling wave solution. A technique is described whereby the measured response is separated into modal components using spatial Fourier transforms. The travelling wave solution is then extracted from each of these modal components using an iterative least-mean-square technique to identify the wavenumbers and wave amplitudes. The technique is applied to vibration measurements obtained experimentally for a single plate under broadband excitation. The waveguide properties from the experimental data are successfully extracted and the errors involved in applying this technique to experimental results are discussed. This method can be used to experimentally determine plate properties, vibrational responses such as energy levels and in the calculation of transmission coefficients for finite coupled structures.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p624.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p559" class="affilation"></a>Measuring Wave Fronts of Inflating Airbags</h2>
<h3>Per Rasmussen, Kim M. Nielsen</h3>
<p class="affilation">G.R.A.S. Sound & Vibration A/S, Skovlytoften 33, 2840 Holte, Denmark</p>
<p><b>ABSTRACT</b><br>
When an airbag inflates rapidly during a car accident, the driver is exposed to a large impulsive wave of sound pressure of short duration that could possibly damage human hearing. The time signals of these impulsive were measured using transducers of various types and sizes in order to investigate the repeatability of the measured results both for each given transducer and between transducers. The aim was to find a suitable way for manufacturers to test airbags and to be able to make meaningful data comparisons.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p559.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p782" class="affilation"></a>Laser Doppler Vibrometer for Measuring Small Amplitude of Vibration Using Synthetic Heterodyne Interferometry</h2>
<h3>Seonggu Kang (1), Jongpil La (2), Heesun Yoon (1), Kyihwan Park (1)</h3>
<p class="affilation">(1) Dept. of Mechatronics, Gwangju Institute of Science and Technology, 1 Oryong-dong, Buk-gu, Gwangju 500-712, Republic of Korea (2) Compressor Development Group, Samsung Gwangju Electronic Company, 1119 Oryong-dong, Buk-gu, Gwangju 500-712, Republic of Korea</p>
<p><b>ABSTRACT</b><br>
A new synthetic heterodyne laser Doppler interferometer based on homodyne interferometer is addressed in this work. Though the homodyne interferometer has the advantages of simple optical configuration and low cost, it requires caution in using an electronic filter such as high pass filter (HPF) to get rid of low frequency electronic noises of the photo diode electronic circuitry. When the vibration amplitude is smaller than at least 1/2 of the wavelength of He-Ne laser, a serious problem of incorrect velocity measurement can be caused since there is non-zero crossing interference signal whose DC value can be eliminated in using the HPF. To solve this problem of using the HPF in the homodyne interferometer, a synthetic interferometer using a mechanical modulation method is proposed in this work by exciting a reference mirror with the displacement larger than the 1/2 of the wavelength. In this work, the analytical work is presented to show how the synthetic interferometer solves the problem of incorrect velocity measurement using the Fourier-Bessel function description of the interference signals. Simulation and Experimental works are also presented to validate the synthetic heterodyne interferometer proposed in the work.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p782.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p410" class="affilation"></a>Modeling the Interaction of Guided Wave with the Welded Support in Pipes</h2>
<h3>Shiuh-Kuang Yang (1), Ping-Hung Lee (1), Jin-Jhy Jeng (2), Jyin Wen Cheng (1)</h3>
<p class="affilation">(1) Department of Mechanical and Electro-Mechanical Engineering, National Sun Yat-Sen University, Kaohsiung, Taiwan, R.O.C. (2) Chinese Petroleum Corp., Taiwan, Kaohsiung, Taiwan, R.O.C.</p>
<p><b>ABSTRACT</b><br>
The guided wave technique plays an important role for the inspection of long-range pipes and large plates in recent years. In pipes, the axis-symmetric guided waves are able to propagate for a long distance with little attenuation, especially the T(0,1) mode. However, the superiority of the guided waves decreases when some complex features on pipe, such as welded supports and bends, etc., interfere with the guided waves. In this paper, a finite element model is applied to study the mode conversion in the welded support when the T(0,1) mode impinges onto it in pipes. From the visualization of FEM, the wave propagates in the support with circular waveform initially and becomes almost a straight waveform later. In addition, the time-frequency analysis recognizes the converted Lamb waves in the support. The finite element model used in this study shows the mode-conversion-phenomenon when waves propagate from the pipe-like structure to the plate-like structure.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p410.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p652" class="affilation"></a>Using Hysteresis Loop and Torsional Shock Loading to Asses Damping and Efficiency of Cyclodrives</h2>
<h3>Vladis Kosse</h3>
<p class="affilation">School of Engineering Systems, Queensland University of Technology, 2 George Street, GPO Box 2434, Brisbane 4001, Australia</p>
<p><b>ABSTRACT</b><br>
Cyclodrives gained popularity in the last 10...15 years. They posses many unique features such as large reduction ratio in one stage and ability to withstand up to 500% shock overloading. They are much smaller than conventional drives with a similar reduction ratio. They posses ‘lost motion’ up to ±28°, which can be attributed to clearances and contact deformation, and it plays much greater role in Cyclodrives performance than in other kinds of drives. Despite many interesting characteristics of Cyclodrives very few research publications are available on Cyclodrive features and dynamics. In this paper a comparative analysis is conducted of Cyclodrives and other kinds of drives with very large reduction ratio in one stage. Results of experimental study of the hysteresis phenomenon in Cyclodrives and damping properties derived from dickey curves under torsional impact load are presented. The static efficiency of Cyclodrives was significantly lover of the dynamic efficiency reported by the manufacturer (in excess of 92.5%) when they are loaded up to the nominal torque, and significantly decreases when they are overloaded to 4 times the nominal torque.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p652.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p32" class="affilation"></a>Finite Periodic Structure of Beam for Low Frequency Structure-Borne Sound Attenuation</h2>
<h3>Yi Yun, C. M. Mak</h3>
<p class="affilation">Department of Building Services Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong</p>
<p><b>ABSTRACT</b><br>
Unwanted vibration in ships, aircraft and buildings is often caused by the operation of machinery and transmitted into the structure through connected beams. The attenuation of vibrational power transmission in low frequencies has been a difficult problem for a long time. Recently, a series of studies about the elastic wave propagation in locally resonant sonic materials have found that phonon-like acoustic structures can have even better sound attenuation performances than before in a lower range of frequencies due to phonon resonance and Bragg interference phenomena. It is also supposed to effectively attenuate low-frequency vibrational waves in a beam-type one dimensional system by using the periodic phonon structure, the decay and transform of flexural waves in a beam with ternary locally resonant elements attached is studied in this paper.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p32.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p387" class="affilation"></a>Online Non-Contact Torsion Sensing Method Using Fiber Bragg Grating Sensors and Optical Coupling Method</h2>
<h3>Yoha Hwang, Jong Min Lee</h3>
<p class="affilation">Intelligent System Research Division, Korea Institute of Science and Technology, Songbuk Hawolgokdong 39-1, Seoul 136-791, Korea</p>
<p><b>ABSTRACT</b><br>
Online measurement of torsion of a rotating shaft has been dominantly conducted by strain-gages combined with either a slip ring or telemetry. However, both methods have severe inherent problems like low S/N ratio, high cost, and difficult installation. FBG (Fiber Bragg Grating) sensor can measure both strain and temperature. It has much superior characteristics compared to strain-gages and has been used in various mechanical engineering applications in recent years. In this paper, a new method using FBG sensors for online non-contact torque monitoring is suggested. This system uses optical coupling to connect FBG sensors on the rotating shaft to instruments at stationary side. A reference FBG sensor on the shaft has been also introduced to compensate the insertion loss change due to rotation. A single optical fiber with three FBG sensors (two for torsion measurement and one for compensation) is installed on the shaft and all instruments are installed at stationary side thereby giving tremendous advantages over a slip ring or telemetry. The suggested system’s superior performance potential is demonstrated with experiments.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p387.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p370" class="affilation"></a>Effect of Axial Force, Unbalance and Coupling Misalignment on Vibration of a Rotor Gas Turbine</h2>
<h3>Abdolreza Askarian (1), S. M. Reza Hashemi (2)</h3>
<p class="affilation">(1) Aerospace Engineering Dep, Sharif University of Technology, Tehran, Azadi Ave. 11365-8639, Iran (2) Mechanical Engineering Dep, Amir-Kabir University of Technology (Tehran Polytechnic), Tehran, Hafez Ave. 424, Iran</p>
<p><b>ABSTRACT</b><br>
Unbalanced rotors and shaft misalignment are the two main sources of vibration in rotating machinery. These undesired vibrations may destroy critical parts of the machine, such as bearings, gears and couplings. There are lots of investigations about effect of unbalance and coupling misalignment upon the critical speeds and vibration amplitudes in rotary machinery. In this paper, effect of various parameters such as rotational velocity, geometry, variation of temperature and Poisson ratio on the natural frequency of rotating shafts were investigated. The equation of motion was derived from Euler-Bernoulli beam model and strain-stress relations. Results show that the effect of spin softening is more important than axial force. For investigation of unbalance and misalignment response in a multirotor system, FEM is used. The spline coupling was modelled in the form of bending spring. The equation of motion is solved by Newmark scheme. Results show that unbalance and misalignment are important in domain of first and second natural frequency, respectively.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p370.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p59" class="affilation"></a>Vibration Analysis of Vibratory Gyros</h2>
<h3>C. S. Chou (1), C. O. Chang (1), F. H. Shieh (2)</h3>
<p class="affilation">(1) Institute of Applied Mechanics, National Taiwan University, No.1, Sec. 4, Roosevelt RoadTaipei, Taiwan, R.O. China (2) Chung-Shan Institute of Sciences and Technology, Taoyuan, Taiwan, R.O. China</p>
<p><b>ABSTRACT</b><br>
The purpose of this paper is to investigate the vibration of a vibratory gyroscope with imperfections. A linear model due to imperfections of material or manufacturing tolerance of a vibratory gyroscope is established. The operations of vibratory gyroscopes without or with imperfections are described under free vibration. Effects of the imperfections in terms of damping, gyroscopic, stiffness and circulation in the governing equations are analysed with multiple time scale method. Effects of the resulting angular frequency variation only and anisoelasticity are investigated via the variation of the elliptical orbit of a reference point on the element relative to a coordinate system fixed on the gyro.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p59.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p795" class="affilation"></a>Frequency Response of Flat Post-Tensioned Concrete Floors: Frequency Coefficient-Root Function Method</h2>
<h3>Charles Jetann (1), David Thambiratnam (1), Stephen Kajewski (1), Anrew Farr (4)</h3>
<p class="affilation">(1) Queensland University of Technology, Faculty of Built Environment and Engineering, School of Urban Development, Gardens Point, Queensland 4000, Australia (2) Farr Engineers Associates, Spring Hill, Queensland 4000, Australia</p>
<p><b>ABSTRACT</b><br>
Vibration is a serviceability limit-state for the design of suspended floor systems in buildings that is not well understood by many structural engineers, and is often ignored. Dynamic response is an important design consideration for slender, two-way floors, particularly for those of post-tensioned concrete construction. At present, there are no reliable design guidelines that deal with this problem. This paper describes a research program, which will enable the development of much needed design guidance on the dynamic behavior of suspended post-tensioned concrete floors. Results from this parametric investigation have led to the preliminary development of new approach for predicting the natural frequency of flat, post-tensioned concrete floor structures. This new method has been named, the Frequency Coefficient-Root Function (FCRF) method. The FCRF method is a revolutionary and convenient tool structural engineers can use to design for the vibration serviceability limit-state of cast-insitu, post-tensioned concrete floor systems.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p795.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p470" class="affilation"></a>Operational Modal Analysis by Using Transmissibility Measurements with Changing Distributed Loads</h2>
<h3>Christof Devriendt, Patrick Guillaume, Gert De Sitter, Steve Vanlanduit</h3>
<p class="affilation">Vrije Universiteit Brussel, Department of Mechanical Engineering, Acoustics and Vibration Research Group, Belgium</p>
<p><b>ABSTRACT</b><br>
Recently a new approach to identify modal parameters from output-only transmissibility measurements was introduced. In general, the poles that are identified from transmissibility measurements do not correspond with the system’s poles. However, by combining transmissibility measurements under different loading conditions, it has been shown that model parameters can be identified. In the previous papers on this topic a single input situation was assumed. In order that the method should be useful for operational modal analysis, where there are in general a number of simultaneous sources, a generalization of the technique with a multiple input assumption is proposed. In this paper the extended technique is demonstrated and validated by means of an experimental test on a beam.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p470.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p817" class="affilation"></a>Influence of Stiffness and Mass Changes on Eigen Frequencies of Beam with Piezo Electric Patch</h2>
<h3>D. Mallikarjuna Reddy, S. Swarnamani</h3>
<p class="affilation">Machine Design Section, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai - 600 036, India</p>
<p><b>ABSTRACT</b><br>
The ability to monitor a structure and detect small damage is of great interest for engineering community. In structural health monitoring, Smart structures with smart elements can continuously monitor their structural integrity use bonded or embedded sensors and actuators. This paper presents a method for damage detection in structure using experimental vibration data that may result from use of such sensors/actuators the structure consists of a cantilever beam and a piezoelectric patch and accelerometer as actuator and sensor respectively. The actuator is used to excite the structure with in given frequency bandwidth and the sensor measures the received signal and influence of damage induced can be analyzed to identify and quantify damage. In this paper damage as different depths of cuts are induced on the beam and here effects are analyzed by observing the changes in power spectral magnitude of vibration response. The variation of power spectrum magnitude of beam due to attached masses at distinct locations also studied.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p817.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p508" class="affilation"></a>Modal Identification of the Wet Modes of a Marine Structure</h2>
<h3>Daniele Dessi, Riccardo Mariani</h3>
<p class="affilation">INSEAN, Dept. of Vibration and Noise, Roma, Italy</p>
<p><b>ABSTRACT</b><br>
In this paper the modal experimental analysis of the bending response of a scaled ship model excited by ambient waves is presented. The physical model, designed to reproduce the global elastic behaviour of a real ship, is made with independent hull portions connected with an elastic supporting beam which the strain gauges are applied to. The identification of the ‘wet’ modes of the elastic beam is performed by using the Proper Orthogonal Decomposition (POD) on the strain gauges signals, whereas the source of excitation of the structures is ‘naturally’ provided by the waves generated in the INSEAN linear basin with a wave-maker.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p508.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p342" class="affilation"></a>New Strategies for Model Validation Using Modal Test Data</h2>
<h3>David Ewins</h3>
<p class="affilation">Imperial College, London</p>
<p><b>ABSTRACT</b><br>
The technology that today we call “Modal Testing” (or “Experimental Modal Analysis”) became a practical reality in the early 1960s, at just about the same time that finite element methods were being developed. Throughout the ensuing 40 years, the primary application of modal testing has been to providing a means of validating the mathematical models that FE methods, and others, provide for the dynamic analysis of engineering structures exposed to vibration environments. However, in the past 5-10 years, dramatic developments in computation capabilities have resulted in a growing imbalance between the theoretical prediction methods and the associated experimental testing methods, particularly in respect of the time (and cost) required to undertake each type of analysis. As a result, there is a growing reluctance to continue with the traditional testing activities that are necessary to validate the models that will be used to design structures. This situation has led to the need for improved testing techniques and this paper describes a number of new ideas and experimental procedures that offer a dramatic improvement in the cost-effectiveness of modal testing for model validation. In summary, these new experimental techniques provide a means to close the widening gap between analytical and experimental activities, which is characterised by (a) marked differences in time and cost demands to acquire the relevant data in the two approaches, and (b) striking differences in the numbers of degrees of freedom typically used to describe the structure’s behaviour (100,000 s in theoretical models and 100 s in tests). Enhancements in testing procedures which can provide order-of-magnitude reductions in testing time, at the same time as order-of-magnitude increases in measurement degrees of freedom, are described. Together, these offer a powerful new approach to model validation using test data.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p342.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p754" class="affilation"></a>An Investigation into the Linearity of the Sydney Olympic Stadium</h2>
<h3>David Hanson, Graham Brown, Ross Emslie, Gary Caldarola</h3>
<p class="affilation">Structural Dynamics Group, Sinclair Knight Merz, St. Leonards, Sydney, NSW 2065, Australia</p>
<p><b>ABSTRACT</b><br>
Modal analysis is based on the assumption that the structure under test can be modelled as a linear, time-invariant system. Many structures exhibit non-linearity across their operating range however, which adds uncertainty to the applicability of results obtained through modal tests with contrived excitations. Operational Modal Analysis (OMA) seeks to overcome this limitation by using the in-service forcing functions to excite the structure. Some structures however, such as large stadia, experience in-service excitations across a wide range of amplitudes. This paper investigates the linearity of such a structure, the Sydney Olympic Stadium, using measurements recorded during a concert. The excitation, mainly crowd induced, differed significantly throughout the concert, corresponding with seated and standing / dancing concert-goers. Separate operational modal analyses were performed with low and high levels of crowd induced excitation, and the modal properties of the structure at these times were compared. This provided an insight into the linearity of the stadium, and the degree to which a single, linear model could represent the structure over its operating range.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p754.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p108" class="affilation"></a>Development of an in-Service Dynamic Model of a Double Deck Passenger Train</h2>
<h3>David Hanson (1), Mark Winton (2), Ross Emslie (1), Graham Brown (1), Bob Randall (3)</h3>
<p class="affilation">(1) Structural Dynamics Group, Sinclair Knight Merz, St Leonards, Sydney 2065, Australia (2) Structures and Dynamics, United Group - Rail, Broadmeadow, Australia (3) Mechanical and Manufacturing Engineering, The University of New South Wales, Sydney, Australia</p>
<p><b>ABSTRACT</b><br>
This paper presents the findings of an investigation into the structural properties of a double deck passenger railcar. The objective of the investigation was to develop an in-service dynamic model about an operational point where the car was travelling at 80km/h over track used in everyday service. A detailed grid of response measurements, providing a spatial definition of the car, were recorded consisting of nearly three hundred accelerometer records in three axes distributed over the structure in more than forty measurement batches while the car was running down the track. Using these measurements, an in-service modal model was constructed by operational modal analysis using the enhanced frequency domain decomposition technique. Of particular interest to this investigation were the primary vertical and lateral bending modes which were found to be coincident, with the lateral mode dominating. The application of whole body vibration weightings however, produced an equivalence of the largely decoupled vibration due to each mode. In this context, the in-operation modal properties are compared with those predicted by a workshop modal test and the operational deflection shapes of the car. The relative merits of these approaches for the modelling of the car in-service are discussed. It is intended that the in-service dynamic model can be used in the prediction and refinement of ride comfort.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p108.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p767" class="affilation"></a>Structural Stress Analysis Undergoing Harmonic Excitation Using Modal Theory</h2>
<h3>Dongyue Liu (1), L. J. Liu (2), Rongying Shen (2), Hongxing Hua (2)</h3>
<p class="affilation">(1) Naval Research Center, 100073 Beijing, China (2) State Key Laboratory of Mechanical system and Vibration, Shanghai Jiao Tong University, 200030 Shanghai, China</p>
<p><b>ABSTRACT</b><br>
Structural interior stress in operational state depends on its dynamics characters and external excitation. In this paper, the stress state of operational structure is firstly analyzed by using experimental modal analysis technique and structure intension theory. Energy distribution of structural every dominant modal can be discussed by extracting practical dominant modal. Consequently structural dynamic stress is calculated by translating complex static and dynamic coupling spatial stress state into simple stress state of each dominant modal. Furthermore, the simply support beam is modeled, and is carried out numerical simulation calculation and damage experiment. The stress of folding static and dynamic at 1/4L is compared to the stress at 1/2L along the longitudinal beam. The results show that maximum stress occurs at the 1/4L location, where static stress is smaller in still state but dynamic stress is bigger under harmonic excitation.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p767.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p198" class="affilation"></a>Optimum Design of Vibration Absorber with Variable Position for an Euler-Bernoulli Beam Under Moving Point Excitation</h2>
<h3>Firooz Bakhtiari-Nejad (1), Hamed Moradi (2)</h3>
<p class="affilation">(1) Department of Mechanical Engineering, Amirkabir University of Technology, Hafez Ave., Tehran, Iran (2) Department of Mechanical Engineering, Sharif Universtity of Technology, Azadi Ave., Tehran, Iran</p>
<p><b>ABSTRACT</b><br>
Vibration absorbers have many applications in reducing the undesirable vibration of a system. Consider an Euler-Bernoulli beam with arbitrary supports which is under a harmonic point excitation that can be set in different positions. The effect of an absorber on reducing the vibration of this beam is studied in this paper. Also, to achieve a more accurate analysis, the effect of the spring mass on the dynamic equations of the vibrating system is considered .The optimum specifications such as spring stiffness, absorber mass and its position are determined by developing and using several algorithms under MATLAB environment. Finally, the equivalent analog circuit of the problem is simulated using the SIMULINK Toolbox of MATLAB. The advantage of this simulation is that one can find the optimum specifications of an absorber for a beam with arbitrary supports under any other types of excitation such as step, ramp, etc.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p198.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p446" class="affilation"></a>Operational Structural Transfer Path Analysis</h2>
<h3>Gert De Sitter, Patrick Guillaume, Christof Devriendt</h3>
<p class="affilation">Acoustics & Vibration Research Group, Department of Mechanical Engineering, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium</p>
<p><b>ABSTRACT</b><br>
A lot of mechanical systems are composed of different subsystems that are coupled by several links. The Transfer Path Analysis aims to identify the operational forces and the most important propagation paths of the vibrations. In this contribution a new technique will be presented which can be used in operational conditions. The proposed technique has several advantages. First of all the disassembling of the system is not necessary anymore which reduces the overall testing time. Secondly, the real boundary conditions are present. In this contribution the theory will be tackled and the procedure will be validated by some simulations.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p446.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p289" class="affilation"></a>Experimental Evaluation of the Modal Damping of Automotive Components with Different Boundary Conditions</h2>
<h3>Giorgio Dalpiaz, Emiliano Mucchi, Stefano Mischiari</h3>
<p class="affilation">EnDIF-Engineering Department in Ferrara, Università degli Studi di Ferrara, Via Saragat 1, I-44100 Ferrara, Italy</p>
<p><b>ABSTRACT</b><br>
In this paper an Experimental Modal Analysis (EMA) program has been carried out on different types of brackets used on diesel engines, and in different boundary conditions with the aim of collecting the damping values in a database. In particular, the EMA has been carried out on brackets in the free-free condition and in the actual clamped condition, highlighting the damping variation with the different boundary conditions. The results of the experimental measurements have been processed with the modal analysis solvers LSCE (Least Squares Complex Exponential) and PolyMAX using the software LMS Test.Lab.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p289.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p120" class="affilation"></a>Investigation of the Dynamic Properties of a Boring Bar Concerning Different Boundary Conditions</h2>
<h3>Henrik Åkesson (1), Tatiana Smirnova (1), Lars Håkansson (1), Ingvar Claesson (1), Thomas Lagö (2)</h3>
<p class="affilation">(1) Department of Signal Processing, Blekinge University of Technology, Sweden (2) Acticut International AB, Gjuterivägen 7, 311 32 Falkenberg, Sweden</p>
<p><b>ABSTRACT</b><br>
The boring bar is one of the most widely used types of tool holder in metal cutting operations. The turning process subjects the tool to vibration, and cutting in deep workpiece cavities is likely to result in high vibration levels. The consequences of such vibration levels are generally; reduced tool life, poor surface finishing and disturbing sound. Internal turning frequently requires a long and slender boring bar in order to machine inside a cavity, and the vibrations generally become highly correlated with the fundamental bending mode of the boring bar. Different methods can be applied to reduce the vibrations, the implementation of the most efficient and stable methods require in-depth knowledge concerning the dynamic properties of the tooling system. Furthermore, the interface between the boring bar and the clamping housing has a significant influence on the dynamic properties of the clamped boring bar. In this paper different cases of boundary condition of the boring bar are presented partly analytically but also experimentally. This paper focuses on dynamic properties of a boring bar that arise due to different clamping conditions of the boring bar introduced by a clamping housing commonly used in the manufacturing industry.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p120.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p279" class="affilation"></a>Energetic Characteristics of Vibration Loads on a Mechanical Object</h2>
<h3>Henryk Kaźmierczak, Jacek Kromulski, Tadeusz Pawłowski</h3>
<p class="affilation">Industrial Institute of Agricultural Engineering, ul. Starołęcka 31, 60-963 Poznań, Poland</p>
<p><b>ABSTRACT</b><br>
Unwanted dynamic reactions (vibrations) disorganize a machine functionally and structurally and determine changes in its technical condition. Dynamic properties of a machine are a derivative of spatial distribution of machine physical properties and boundary conditions as well as the way of connecting it with the prime mover. In the study of energetic profiles of vibration loads in a machine, the method of dynamic susceptibility is applied to build the analytical model of the system, and the method of experimental modal analysis is used to identify machine dynamics profiles. The paper presents the application of the analysis method for distribution of dynamic load powers to describe the technical condition of an object and the degradation process of a mechanical object. The method of energetic modelling for machine vibration loads helps to establish separately the power of dumping forces and inertia forces, and dynamic stiffness forces in a complex mechanical system. This method allows assessment of the impact of particular input functions and components of force power spectra on the life curve of an object. It can also be a method of experimental review for numerical strength models obtained by finite element methods. The knowledge of spatial load distribution in a mechanical object in the functions of frequency and operating time helps identify elements that are subject to overloads. Changes proposed on the basis of vibration load analysis help avoid overloading and braking machine components.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p279.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p801" class="affilation"></a>Modal Analysis of Asynchronous Motor Vibration</h2>
<h3>Jiri Vondrich</h3>
<p class="affilation">Department of Mechanics and Materials Sciences, Faculty of Electrical Engineering, Czech Technical, University in Prague, Technicka 2, 166 27 Prague 6, Czech Republic</p>
<p><b>ABSTRACT</b><br>
The modal analysis method is one of the research branches, rapidly developed recently in consequence to the availability of new measurement and computational means. The aim of the research was to apply this method to investigate the vibratory processes of electrical rotary machines in transient states. Transient states can occur, e.g. in the case of driving the direct current motor by a voltage step or in a sudden relief of the load on the synchronous motor. Mechanical impacts are transmitted through the frame and feet of the motor and from the motor feet to the foundation plate. They can cause, for large magnitudes, even deformation of the windings. The modal properties of an asynchronous motor have been investigated with excitation at a number of measuring points spread over the surface of the machine. The results can be useful for designing the motor frame and for the construction of the appropriate fixity.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p801.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p93" class="affilation"></a>Modal Analysis of Large Structures Submerged in a Fluid</h2>
<h3>John Marco, Ian MacGillivray</h3>
<p class="affilation">DSTO, Department of Defence, PO Box 4331, Melbourne, VIC 3001, Australia</p>
<p><b>ABSTRACT</b><br>
Vibration of ship appendages that operate underwater during their service life can be excited by either fluid flow over their surfaces or by internal ship-generated structural loads. In order to assess the effect of these excitation loads the modal frequency response of the appendage needs to be determined in water. Assessing the modal response of structures in a vacuum or in air via experimental and numerical means has matured, whereas the modal response of a structure in a dense fluid can still be a challenge. This paper will describe a number of techniques for handling the fluid loading and will use as an example a large wing-like hydrofoil structure to show the effect and importance of the fluid loading.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p93.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p505" class="affilation"></a>Study on the Dynamic Tilt Characteristics of Optical Pickup Actuators Considering Electromagnetic Nonlinearities Using Coupled-Field Analysis</h2>
<h3>Jong-Jin Lee, Jae Eun Kim, Sam-Nyol Hong, Eui-Seok Ko, Byung-Hoon Min</h3>
<p class="affilation">LG Electronics Digital Storage Research Lab., 16 Woomyeon-Dong, Seocho-Gu, 137-140, Seoul, Republic of Korea</p>
<p><b>ABSTRACT</b><br>
An optical pick-up actuator is an objective lens moving device that provides means to accurately follow the track of a disc with constant working distance. It is composed of a moving part and magnetic circuit part. The moving part supported by suspensions is actuated in 3-axis motions by Lorentz force which is generated by magnetic circuit. When an actuator follows the deflection of a disc, unbalanced force distributions may occur on the moving part by magnetic nonlinearities. This phenomenon deteriorates the static and dynamic tilt characteristics of the actuator. If the dynamic tilt shows nonlinear characteristics, the actuator has insufficient tilt margin to follow disturbed disc motions. According as an optical storage becomes high-density as in the Blu-lay or HD-DVD, an adequate tilt margin analysis and exact frequency response prediction becomes key design factors to determine the static and dynamic performance of an actuator. Since the previous studies only treated the linear characteristics of tilt, they provide us with inaccurate results. In this paper, considering structural as well as magnetic nonlinearities, we predicted tilt properties in all moving ranges and thus we were able to obtain more acceptable results by finite element method. First, we analyze magnetic nonlinearities at each position. Second, on the basis of magnetic analysis results at the first step, we predict exactly dynamic tilt properties of the moving part with the calculated magnetic nonlinearities. The frequency response was also quite well evaluated by coupled-filed analysis. Finally, we verified our proposal by comparing the numerical results with those of experiment.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p505.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p352" class="affilation"></a>Shimmy Evaluation Using Theoretical Multibody Model and Experimental Techniques</h2>
<h3>Jung Hoon Kim (1), Yeon June Kang (1), Ho Won Lee (2), Dong Ho Yoo (3)</h3>
<p class="affilation">(1) School of Mechanical and Aerospace Engineering, Seoul National University, Sillim-dong San 56-1, Kwanak-gu, Seoul, 151-742, Republic of Korea (2) Mechanical Science & Engineering, University of Illinois - Urbana - Champaign, Mc 244, 158 meb, 1206 w green, urbana, IL 61801, USA (3) Applied Technology Research Dept., Hyundai Mobis, Mabook-ri 80-10, Guseong-eup, Yongin-shi, Gyunggi-do, 449-910, Republic of Korea</p>
<p><b>ABSTRACT</b><br>
Shimmy is the vibration in the steering rotational direction during steady-state running and gives annoyance to passengers. Passenger’s comfort is a critical characteristic in vehicle. In this study, both a theoretical linear model and a numerical model are used to predict and optimize the frequencies of shimmy related modes and the level of vibration for a vehicle. A theoretical multibody linear model of 48-DOF was used for quasi-static analysis and modal analysis. The theoretical model was verified by comparing the results of modal analysis with those of a modal experiment for front suspension system using CADA-X program. The quasi-static analysis results of the theoretical model were compared with those of an ADAMS model. A full vehicle model using ADAMS was also verified with the results of the modal experiment and chassis dynamometer experiments for shimmy reproduction. From experiments and simulations, it was found that the wheel longitudinal vibration mode was the most dominant source of shimmy vibration. In addition, 13 design parameters of the front suspension system including compliance and geometric factors for reducing shimmy level were selected based on the experimental results. By performing 27 orthogonal simulations using Taguchi methodology, an optimal combination of design parameters was constructed. Through modal analysis of the theoretical model with the optimized design parameters, it was found that the wheel longitudinal vibration mode changed into two local vibration modes. Finally, a simulation of the numerical model verified that the suggested design parameters resulted in shimmy vibration reduction.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p352.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p276" class="affilation"></a>System Reduction in Nonlinear Multibody Dynamics of Wind Turbines</h2>
<h3>Kristian Holm-Jørgensen (1), Søren R. K. Nielsen (1), Rune Rubak (2)</h3>
<p class="affilation">(1) Department of Civil Engineering, Aalborg University, Sohngaardsholmsvej 57, DK-9000 Aalborg, Denmark (2) Siemens Wind Power A/S, Borupvej 16, DK-7330 Brande, Denmark</p>
<p><b>ABSTRACT</b><br>
In this paper the system reduction in nonlinear multibody dynamics of wind turbines is investigated for various updating schemes of the moving frame of reference. In one case, the moving frame of reference is updated to a stiff body, relative to which the elastic deformations are fixed at one end. In the other case, the stiff body motion is defined as the chord line connecting the end points of the beam, and the elastic deformations are simply supported at the end points. The system reduction is performed by discretizing the spatial motion into a set of rigid body modes and linear elastic eigenmodes determined from an FE-beam model complying to the definitions of the stiff bodymotions. Moreover, certain nonlinear effects have been included. These encompass the non-conservative rotation of the aerodynamic load during large elastic deformations and application of the aerodynamic and inertial loads in the deformed state. To illustrate the method a numerical example of a wind turbine blade with a length of 45 m attached to a rotor shaft supported by two bearings is used. The reduced model based on a truncated modal expansion has been compared with the full FE model in both linear and nonlinear analyses. The updating based on an expansion using simply supported eigenmodes turns out to be the most favourable in reducing the displacements from the moving frame.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p276.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p19" class="affilation"></a>A Method of Measuring the Axial Elastic Modulus of a Sandwich Cylinder Based on Modal Testing</h2>
<h3>Li Ping, Su Shenjian, Zuo Jianli</h3>
<p class="affilation">Research Institute of Physical and Chemical Engineering of Nuclear Industry (IPCE), No.168 JinTang Road, TianJin, 300180, China</p>
<p><b>ABSTRACT</b><br>
The axial elastic modulus is one of the most important parameters of the sandwich cylinder, which is made of metal and one or two kinds of complex material. But it was difficult to measure the elastic modulus exactly by means of routine material test because the cylinder was not easy to be made into a standard specimen. This paper presents a non-destructive method of measuring the axial elastic modulus of the sandwich cylinder based on modal testing. In this method, the axial elastic modulus can be determined by solving the bending vibration equations of the cylinder, and the modal testing provides the required bending frequencies in the equations. The shear modulus can also be determined simultaneously. The method was proved to be practicable by measuring an aluminium cylinder whose elastic modulus is known, and the errors were evaluated. The results of testing sandwich cylinders are also presented.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p19.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p675" class="affilation"></a>Comparison of FE and Modal Models in Model Updating Methods</h2>
<h3>M. Reza Ashory, Ehsan Jamshidi</h3>
<p class="affilation">Department of Mechanical Engineering, University of Semnan, Semnan, Iran</p>
<p><b>ABSTRACT</b><br>
One of the most important applications of modal testing is the validation of the analytical model of dynamic structures by comparing the experimentally driven modal parameters with those of analytical models. Once the analytical model is validated, it can be used with confidence for further analysis such as response prediction, structural coupling, stress analysis, life time prediction, etc. In this article, the dynamic properties of a steel plate and a 3D steel frame are investigated using the theoretical method of Finite Element Method (FEM) and the experimental method of Modal Testing. Finite Element Analysis is used to determine the best accelerometer locations and the suitable frequency range in order to conduct Modal Testing. A 24-channel spectrum analyzer is used to derive the natural frequencies, mode shapes and damping ratios from Frequency Response Functions (FRFs). Finally, the dynamic properties obtained from Modal Testing are compared with those of the Finite Element Method (FEM). The mass and stiffness error matrices are calculated. It is shown that the dynamic behaviour of the new model and the experimental one are close together although the error can not be exactly located in the models. Based on this study some remarks are pointed out in using model updating methods.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p675.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p820" class="affilation"></a>The Mass-Loading Effect of Accelerometers on MAC Criterion</h2>
<h3>M. Reza Ashory (1), Hamid Daiyan (2)</h3>
<p class="affilation">(1) Department of Mechanical Engineering, University of Semnan, Semnan, Iran (2) Department of Engineering, Islamic Azad University, Semnan, Iran</p>
<p><b>ABSTRACT</b><br>
Traditionally, the mass-loading effect of accelerometers is avoided by using small accelerometers and, as a result, the effects of these mechanical devices on the measured FRFs are often considered to be negligible. However, there is no known proof to this belief. There are many cases in which the mass of accelerometers are not negligible compared to the mass of structures. The MAC graph is considered as one of the most important criterions for comparison of mode shapes of different models of a structure. This article considers the effect of mass of accelerometers on MAC criterion.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p820.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p572" class="affilation"></a>Transient Vibration Analysis for Generating Low Electrical Power</h2>
<h3>Mikail F. Lumentut (1), Kian K. Teh (2), Ian M. Howard (2)</h3>
<p class="affilation">(1) Research Student, Department of Mechanical Engineering, Curtin University of Technology, Australia (2) Department of Mechanical Engineering, Curtin University of Technology, Australia</p>
<p><b>ABSTRACT</b><br>
This paper presents a method for simulating low electrical power resulting from the transient vibration of a coupled piezosensor-plate structure using numerical finite element analysis. Love-Kirchhoff’s plate theory, together with the piezoelectric constitutive equations were used to analyse the dynamic governing equations using the Lagrangian method. The piezoelectric direct mode effects generate polarity of the electric field due to an input transient force where the piezoelectric element was bonded onto the upper surface of the plate structure. Four node rectangular finite elements with twelve degrees of freedom per element were used for the coupled piezosensor-plate structure. The Newmark-β numerical differential equation solution techniques were used within the MATLAB environment to simulate the resulting transient displacement and electric voltage responses. In this case, Rayleigh’s proportional damping was used with damping constants chosen based on experimental results. The results obtained from the numerical modelling are compared with experimental work.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p572.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p531" class="affilation"></a>Operational Modal Analysis in Presence of Unknown Varying Harmonic Forces</h2>
<h3>Patrick Guillaume, Christof Devriendt, Steve Vanlanduit</h3>
<p class="affilation">Vrije Universiteit Brussel, Dept. of Mechanical Engineering, Pleinlaan 2, Brussel, Belgium</p>
<p><b>ABSTRACT</b><br>
In many applications of operational modal analysis one is confronted with unknown harmonic forces. These harmonic components are usually clearly present in the measured response data. The classical approach to deal with such data consists in eliminating these disturbing components from the data. Several techniques can be used to do so. However, when the frequency of these harmonic components varies during the measurements, this is not always obvious. In this contribution, an alternative approach will be proposed to deal with harmonic disturbances. This approach is based on parametrically identified multivariable transmissibilities.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p531.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p312" class="affilation"></a>Dynamic Response of Box-Type Sonar Structure</h2>
<h3>Sameer Abdul Azeez, O. R. Nandagopan</h3>
<p class="affilation">Naval Physical & Oceanographic Laboratory, Kochi 682 021, India</p>
<p><b>ABSTRACT</b><br>
Emerging trends in hull-mounted submarine sonar systems call for compact modular structures. Typical configurations include linear, planar, cylindrical, and spherical. This paper examines a novel type of sonar structure. It is an open box-type, cuboidal in construction, with stiffened end-flanges and multiple openings for hydrophone fitment. The response of the structure to shock load was evaluated using numerical techniques and validated through experiments. Eight-noded linear solid finite elements were used for modeling. Eigen analysis was done using Lanczos method. Shock load dictated by Naval Shock Standards was applied in the longitudinal and transversal directions in the horizontal plane. Modal transient dynamic analysis was performed and the dynamic acceleration response obtained. Validation experiments were executed on “Impact Shock Test Machine” and response measured using accelerometers. The numerical and experimental results are in good agreement. It is observed that shock amplification is appreciable in transversal axis and negligible in longitudinal axis. This study aids sonar engineers in structural integrity issues associated with onboard installation.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p312.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p38" class="affilation"></a>Influence of a Rectangular Plate Inhomogeinity on Natural Frequencies of a Clamped Rectangular Plate</h2>
<h3>Valeri Lenchine</h3>
<p class="affilation">VIPAC Engineers & Scientists Ltd, 17~19 King William Str., Kent Town, SA 5068, Australia</p>
<p><b>ABSTRACT</b><br>
Natural frequencies and mode shapes of rectangular and circular plates are well studied as they are common for many engineering applications. It is possible to utilize different approximate methods. However implementation of such methods in case of a distributed structural inhomogeneity frequently leads to very complex procedure. The goal of the present work is to find comparatively simple solution for clamped rectangular plates with rectangular segment placed on its surface. Such sort of design is very important for installation of equipment on deck and floor. Influence of the inhomogeneity on the plate fundamental frequency is explored in the paper. An analytical solution is developed for calculation of fundamental frequency of a clamped rectangular plate. The solution is gathered in a dimensionless form as a function of the plate dimensions and material properties. Influence of an added plinth- like structure on the plate fundamental frequency is considered utilizing two approaches. First one is based on the modal stiffness and mass concept. Another one employs the perturbation method technique. Simulation runs were performed to verify accuracy of the developed methods. Deviation between fundamental frequencies determined by the derived formulas and FEM calculations is within reasonable limits. However formula based on the perturbation approach gives more accurate result. Nonetheless any of the proposed methods can be employed in engineering practice for approximate calculations to determine influence of plinth inhomogeinity on the fundamental frequency of the clamped rectangular plate.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p38.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p667" class="affilation"></a>Vibration Analysis of Mindlin’s Sandwich Plate (FSDT) Under Random Excitation</h2>
<h3>Vedat Dogan, Yeliz Erkal</h3>
<p class="affilation">School of Aeronautical and Astronautical Engineering, Istanbul Technical University, Istanbul, 34469, Turkey </p>
<p><b>ABSTRACT</b><br>
In this paper, vibration analysis of a sandwich plate modeled within the First Order Shear Deformable Theory (FSDT) under random excitation is presented. It was considered that the sandwich plate is thick, and the CPT (Classic Plate Theory) is no longer applicable, therefore, one of the shear deformable plate theories, the FSDT, is adapted for the structural formulations. The sandwich plate is assumed to be simply supported with movable edges. One of the faces of the sandwich plate is exposed to Gaussian stationary random loads with zero mean. Both uniformly distributed and point random loads are considered. Thermal effect is also taken into account. Root Mean Squares (RMS) of deflection responses are computed and compared by using both the CPT and the FSDT. Spectral density of the responses is also presented. A parametric study is conducted to show the effects of scattering in the geometry of the sandwich plate (both face and core), characteristics of loading and temperature change on the sandwich deflection response.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p667.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p357" class="affilation"></a>Detection of Damage Location in Structures Using Operating Deflection Shape</h2>
<h3>Wonki Bae, Yongsoo Kyong, Semyung Wang, Kyihwan Park</h3>
<p class="affilation">School of Mechatronics and Information Engineering, Gwangju Institute of Science and Technology, 1 Oryong-dong, Buk-gu, Gwangju 500-712 Republic of Korea</p>
<p><b>ABSTRACT</b><br>
It is important to figure out the dynamic characteristics of a mechanical system for the purpose of safe design. The most widely used method to grasp the inherent dynamic characteristics is Modal analysis which gives us information of modal parameters, such as natural frequency, damping ratio and mode shape vector. However, as mechanical systems get larger and more complicated, difficulties on how to set boundary and excitation conditions arise in modal analysis. Surely, the actual vibration of mechanical systems varies with surrounding conditions, which are temperature, rpm, air flow, pressure, load and so on. Therefore, another method known as Operating Deflection Shape (ODS) is needed to deal with those situations that Modal Analysis cannot do. ODS shows structural vibrations under real operating conditions. Also, rapid measurement not influencing the dynamic characteristics of the structure is required for ODS. It is desirable to use a Laser Scanning Vibrometer (LSV) which has no contact with the structure. In addition, if it is possible to check whether the structure is healthy or not, the structure could be prevented from being destroyed. For that reason, an ODS program is developed using LSV, and damage detection is introduced through this program. In this paper, damage locations of structures are detected using ODS and LSV.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p357.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p187" class="affilation"></a>Eigenfrequency Computation by the Finite Sine Transform Method on a Rectangular Plate Carrying Arbitrary Number of Concentrated Masses and Springs</h2>
<h3>Yin Zhang</h3>
<p class="affilation">State Key Laboratory of Nonlinear Mechanics (LNM), Institute of Mechanics, Chinese Academy of Sciences, Beijing 100080, People’s Republic of China</p>
<p><b>ABSTRACT</b><br>
A generalized finite sine transform method (FSTM) is presented in this paper and applied to the eigenfrequency computation of a rectangular plate with arbitrarily distributed concentrated masses and translational springs. Compared with the analytical-and-numerical combined method (ANCM), FSTM keeps the same number of mode shapes in the system eigenfrequencies computation in order to have the convergence. However, unlike ANCM or the finite element method (FEM), whose eigenfrequency computation depends on the number of mode or element. The eigenfrequency computation by FSTM is mainly dependent on the total number of concentrated masses and springs. Therefore, the FSTM computation on the system eigenfrequencies is much faster when the total number of concentrated masses and springs is small.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p187.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p200" class="affilation"></a>Propagation Phase Representation in 3D Space Using Poles and Zeros in Complex Frequency Plane</h2>
<h3>Yoshinori Takahashi (1), Mikio Tohyama (2), Kazunori Miyoshi (1)</h3>
<p class="affilation">(1) Kogakuin University, Tokyo, Japan (2) Waseda University, Tokyo, Japan</p>
<p><b>ABSTRACT</b><br>
This paper describes the transfer function, including the coherent sound field, as the increased distance between source and observation points, from the point of view of the number of zeros in the complex frequency plane. The authors estimated the propagation phase obtained by linear regression analysis of the narrow-frequency-band phase characteristics of the minimumphase component of the transfer function. The direct sound field estimated from the propagation phase of the minimum-phase characteristics consequently seems to be the coherent field within the critical distance. We determined that the zeros drift based on complex-integration analysis. When the sound source distance (SSD) increases, the zeros move toward a higher frequency; thus, an accumulated phase is produced following the propagation phase. When the SSD is long, even in the coherent field, we could confirm a pole-line around the theoretical value.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p200.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p102" class="affilation"></a>Dynamic Response Analysis of Rectangular Perforated Plates with Varying Sizes of Circular Perforation Holes</h2>
<h3>Deepak C. Patil, S. S. Gawade, Kiran D. Mali</h3>
<p class="affilation">Department of Mechanical Engg., Rajarambapu Institute of Technology, Rajaramnagar, India</p>
<p><b>ABSTRACT</b><br>
In this work vibration characteristics of rectangular perforated plates with varying sizes of circular perforation holes arranged in diagonal array are investigated. Natural frequencies of free vibration of the perforated plates and the corresponding mode shapes are obtained experimentally and also numerically. Numerical analysis of dynamic characteristics of perforated plates is carried out using ANSYS, the FEM analysis software package and the experimental analysis is carried out using FFT analyzer, accelerometer and impact hammer. Parameters defining the geometry of holes in a perforation array are presented, as well as the ratio of modal resonance frequencies of a perforate to those of a corresponding solid panel, termed the effective resonance frequency is introduced. In addition, the curve fitting technique is utilized to find the relationship of the mass remnant ratio with the effective resonance frequency. The functions obtained from curve fitting can be used to predict accurately the effective resonance frequencies of wide range of perforation geometries.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p102.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p821" class="affilation"></a>Recent developments in applications of microperforated panel absorbers</h2>
<h3>Kimihiro Sakagami(1), Masayuki Morimoto(1) and Motoki Yairi(2)</h3>
<p class="affilation">(1)Environmental Acoustics Laboratory, Department of Architecture
Graduate School of Engineering
Kobe University
Rokko, Nada, 657-8501 Kobe
Japan
(2)Kajima Technical Research Institute
Kajima Corporation
Tobitakyu, Chofu, 182-0036 Tokyo
Japan</p>
<p><b>ABSTRACT</b><br>
Microperforated panel (MPP) absorbers are promising as a basis for the next-generation of sound absorbing materials. A microperforated panel absorber is backed by an air-cavity with a rigid-back wall and its typical use is for a sound-absorbing ceiling. However, MPPs have some limitations and disadvantages: its sound absorbing mechanism is limited to a Helmholtz resonator caused by perforations with air-cavity and effective absorption is limited to the resonance frequency range. There is also a problem when MPPs are used as a sound absorbing finish of room interior surfaces because typical MPPs are made out of thin limp materials and are not strong enough. In order to solve these problems, the research at Kobe University has focussed on the followings: (1) application of MPPs for room interior surface finishings, including applications of honeycomb MPPs, (2) multiple-leaf MPP absorbers. The main results from these projects are reviewed in this paper.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p821.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p825" class="affilation"></a>Effectiveness of Noise Barriers Tilted Towards the Traffic Way Over Bridges</h2>
<h3>M.Abd El Gawad Saif (1), A. A. Mahmoud (2)</h3>
<p class="affilation">(1) Housing & Building National Research Center (HBRC) Dokki, Giza, Egypt (2) National Institute for Standards, Egypt</p>
<p><b>ABSTRACT</b><br>
Traffic noise over bridges and its impacts can be substantially reduced with road side barriers. A single barrier erected on one side of a bridge way can often provide the most effective solution. A single barrier may not always be sufficient, particularly in urban sittings. In these cases, barriers may be necessary on both sides of the bridge. This paper presents a study of the effectiveness of barriers tilted towards the traffic way with different angles and shapes to reduce the effect of the reflected sound waves from the second barrier. The insertion loss was determined at many points distributed horizontally and vertically behind the barrier.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p825.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p343" class="affilation"></a>Acoustic Barrier for Transformer Noise</h2>
<h3>Ruisen Ming</h3>
<p class="affilation">SVT Engineering Consultants, Leederville, WA 6007, Australia</p>
<p><b>ABSTRACT</b><br>
In this paper, an acoustic barrier is employed for solving the environmental problem imposed by transformer humming noise on nearby communities. A SoundPlan model was created to quantify the noise emission and to optimise the design for maximizing the barrier performance. Based on the requirements and limitations in the substation of interest, the acoustic barrier is designed consisting of absorptive and tonal sections. In-situ measurements have been taken to assess the barrier performance. Both predicted and measured results demonstrate that the acoustic barrier is an effective measure for mitigating transformer humming noise emission.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p343.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p570" class="affilation"></a>Study the Panel and Helmholtz Resonances of a Micro-Perforated Absorber</h2>
<h3>Y. Y. Lee (1), C. F. Ng (2), C. K. Hui (2)</h3>
<p class="affilation">(1) Department of Building and Construction, City University of Hong Kong, Kowloon Tong, Kowloon, Hong Kong SAR (2) Department of Civil and Structural Engineering, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR</p>
<p><b>ABSTRACT</b><br>
In this study, the absorption of an absorber, which considers the three effects, micro-perforation, panel resonance and Helmholtz resonator, is investigated. The theory developed for the micro-perforated absorber is based on that the impedances of the three effects are in parallel and connected to that of the air cavity in series. In previous studies, these three effects were not considered simultaneously for acoustic absorber. It can be concluded from the theoretical and experimental results that the panel and Helmholtz resonance can enhance the absorption bandwidth of a micro-perforated absorber.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p570.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p274" class="affilation"></a>Localization and Identification of Persons and Ambient Noise Sources Via Acoustic Scene Analysis</h2>
<h3>Alexej Swerdlow, Kristian Kroschel, Timo Machmer, Dirk Bechler</h3>
<p class="affilation">Institut für Nachrichtentechnik (INT), Karlsruhe Institute of Technology (KIT), Universität Karlsruhe (TH), Kaiserstr. 12, 76128 Karlsruhe, Germany</p>
<p><b>ABSTRACT</b><br>
There are diverse areas of application for the acoustic scene analysis, consisting of localization and identification of acoustically observable sound sources. In particular, the man-machine interaction in the broadest sense is of peculiar interest. In this paper a method for the passive acoustic localization of sound sources using time difference of arrival (TDOA) estimates in microphone pairs as well as an approach for the classification of ambient noise sources, based on autoregressive (AR) models, are presented. Therewith, classification of individual sound source categories is possible, although their spectral characteristics can vary significantly.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p274.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p502" class="affilation"></a>Noise Source Identification in Magnetic Field Using SVDD (Support Vector Data Description)</h2>
<h3>Dong-Chul Kwon (1), Jong-Bok Lee (1), Il-Kwan Ko (1), Dae-Sung Kang (1), Kyoung-Kook Kim (2), Hoon Heo (1)</h3>
<p class="affilation">(1) Department of Control & Instrumentation Engineering, Korea University, 1-5ka, Anam-Dong Sungbuk-ku, Seoul 137-701, Korea (2) Segye Scientific Co.,LTD., Duck-bong B/D, 41, Garak-Dong Songpa-ku, Seoul 138-160, Korea</p>
<p><b>ABSTRACT</b><br>
In order to deal with noise problem, successful identification of noise in the system is very important. For the purpose adequate method to find its characteristics must be formulated. In the study, the SVDD (Support Vector Data Description) is utilized to identify the noise in magnetic fields. Much of the study has been carried out to figure out the normality and abnormality for the system determined based on the generated signal in accordance with environmental conditions. In the paper, magnetic field signal from electric system is studied. Besides the SVDD, one of the most well-known one-class classification methods is used to classify the magnetic field signals, which are compared to conventional classification methods and stochastic analysis methods as well. Experiment confirms simulation results.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p502.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p726" class="affilation"></a>Extending the Usability of Near-Field Acoustic Holography and Beamforming by Using Focalization</h2>
<h3>Filip Deblauwe (1), Karl Jansen (1), Maxime Robin (2)</h3>
<p class="affilation">(1) LMS International, Interleuvenlaan 68, B-3001 Leuven, Belgium (2) MICROdB, 7B Allée Claude Debussy, F-69130 Ecully, France</p>
<p><b>ABSTRACT</b><br>
In view of source localization techniques, two methods, Near-Field Acoustic Holography (NAH) and Beamforming, are widely used and well-known techniques. Both techniques have their advantages and disadvantages. Near-field Acoustic holography, the oldest commercially available method, has as major advantage its spatial resolution being equal to the microphone spacing and independent of frequency. This makes it a very powerful technique for low frequency problems. However when trying to analyse higher frequencies, the method becomes very tedious from a measurement standpoint. Beamforming, a far-field technique, has as major advantage that with a limited amount of measurement channels a relative large frequency range can be analysed, making the measurement sequence very simple. On the other hand, Beamforming has as disadvantage that its spatial resolution is proportional to the wavelength making the method not really useful for frequencies under 2000 Hz. In this paper, a technique called focalisation is discussed which can ameliorate the shortcomings from NAH and Beamforming. Focalisation is a near-field beamforming technique that can be used on data taken for NAH to extend the frequency range and double the usable frequency range for the same microphone spacing. In case of beamforming the same array can be used to take data in the near-field. When using focalisation in this near-field data, the spatial resolution is improved by a factor of 2. In addition, the focalisation allows calculating the sound power which is not possible with beamforming.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p726.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p322" class="affilation"></a>Sound Propagation Through a Heat-Exchanger Tubes Array in Power Boiles</h2>
<h3>G. S. Jiang (1), L. S. An (1), J. Tian (2), G. Q. Shen (1), B. Jiang (1)</h3>
<p class="affilation">(1) North China Electric Power University, Key Laboratory of Condition Monitoring and Control for Power Plant Equipment of Ministry of Education, Baoding, 071003, P. R. China (2) Institute of Acoustics, Chinese Academy Science, Beijing, 100080, P. R. China</p>
<p><b>ABSTRACT</b><br>
In this paper, a mathematical model of leakage sound propagation through a heat exchanger tubes array in boilers is established, which is based on the Twersky’s sound scattering theory, transmission grating diffraction theory, Fabry-Perot’s interference principle, and algebraic iteration method. The tubes array is made up of large number periodically arranged tubes immersed in air. Its acoustics transmission properties are examined experimentally and theoretically. The stopping frequency, passing frequency and its bandwidth of leakage sound through the tube arrays with different structure parameter are calculated. The definition of “deaf-band’ and “audible-band” of inner tube leakage sound transmission of tube array are given. The experiments of sound propagation characteristic through tube array using electro-acoustic spectral and real air leakage spectral are studied respectively. It was tested that the “deaf band” position of electro-acoustic spectrum is consistent with the theoretical estimation. However, the width is wider than theoretical prediction. The transmission properties of leakage sound spectral is well consistent with theoretical one at low frequency, but different at high frequency. The reason is that the second sound radiation is produced by the interaction between leaking ejection fluid and tube array. The sound transmission characteristic with different rows is concluded at the same time. It offers the evidence for the orientation and location of leakage source well. As same as the phononic crystals, the tube array structure has stop effect and pass effect on leaking sound propagation. The leaking sound radiation in tube array includes leaking jet noise and the second order noise caused by the interaction between the leaking jet and tube array.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p322.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p375" class="affilation"></a>Ranking of Partial Noise Sources and Noise Control Measures</h2>
<h3>Matias Aura (1), Lasse Lamula (2), Kari Saarinen (2), Kari Saine (1)</h3>
<p class="affilation">(1) Wärtsilä Finland Oy, Vaasa, Finland (2) VTT Technical Research Centre of Finland, Tampere, Finland</p>
<p><b>ABSTRACT</b><br>
Sound radiation of an object often consists of several sources. These partial sources may differ in size, material and sound radiation properties. The basis for successful noise control is the ranking of these sources. Traditionally this task is solved using sound intensity measurement or by excluding separate noise sources using partial enclosures. The same approach can be used to assess the effectiveness of noise control measures. Alternative methods are calculation of surface velocity distribution from the measured sound pressures or approximation of radiated sound power level using the measured velocity distribution. In this paper the feasibility of a rather simple and straightforward method is studied. The surface velocity distribution is measured with a laser vibrometer. The measured data is used as excitation for boundary element calculation to estimate the sound power level of a partial source. The potential limitations and errors of the method are studied using FEM and BEM modeling. At high frequencies the errors turned out to be smaller than the accuracy of standardized sound power measuring methods. At low frequencies the errors are higher but the A-weighting reduces their significance. The method was applied to measure the sound power level of a camshaft cover of a large diesel engine and thereby to assess the efficiency of proposed low noise covers. A comparison with intensity method is made and the supremacy of the studied method is shown.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p375.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p705" class="affilation"></a>Neural Techniques for Source Identification</h2>
<h3>Neil McLachlan (1), Marco Paviotti (2), Stylianos Kephalopoulos (2), Dinesh Kant Kumar (3)</h3>
<p class="affilation">(1) School of Behavioral Science, University of Melbourne, 3052, Victoria, Australia (2) European Commission, DG JRC, 21020 Ispra, Italy (3) School of Electronic and Computer Engineering, RMIT, Melbourne, Australia</p>
<p><b>ABSTRACT</b><br>
Noise source separation is a key issue in environmental noise assessment and of particular interest in the implementation of the European Environmental Noise Directive (END), since the contribution to the overall noise level from each single source should be evaluated separately. This, because concerning noise reduction measures each noise source should be eventually reduced independently from the other sources and the effect of the single noise source reduction should be readily compared to the corresponding noise of other sources, and to the health benefits. A technique which is based on wavelet analyses was tested to evaluate how far these concepts could be developed to effectively assist reaching these objectives. This technique is applied here and evaluated using noise long-term measurement data of campaigns performed in Italy in the context of the HARMONOISE and IMAGINE projects funded by the European Commission. Moreover, a proposal is made for using the same techniques to assess the physiological human response to specific noise sources. A metric is introduced which considers each single event in relation to the environment where this happens and to the subjective feeling that this might evoke in the person. Brief time periods of the noise recordings obtained during the experimental campaigns in a real urban environment were used to test the technique. Subsequently, an attempt was done to separate the noise of the cars, motorbikes, buses, airplanes, trains and that produced by the local human voices. Characteristics of the sound signal will be shown, which are used to discern a specific sound source signal from another; these could be used in the future as alternative noise indicators.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p705.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p310" class="affilation"></a>Microphone Array Beamforming and Methods for the Reconstruction of Ducted Acoustic Sources</h2>
<h3>Teresa Bravo, Cédric Maury</h3>
<p class="affilation">Département de Génie Mécanique - Secteur Acoustique, Laboratoire Roberval, Université de Technologie de Compiègne, BP20529, F-60205, Compiègne, France</p>
<p><b>ABSTRACT</b><br>
Methods for noise source identification are a key point to develop research in nacelle noise reduction technologies. In this work, two different approaches, beamforming and inverse methods, have been assessed for the characterisation of in-duct sources. An analytical model has been implemented for the sound field due to elementary sources in a hard-walled duct with non-reflecting terminations. The data field is provided by a uniformly-distributed array of microphones located in a cross section of the circular duct. A comparison between both approaches has been performed as a function of the two main parameters that influence the reconstruction results: the axial distance between the sensor array and the sources, and the frequency range considered. Different beamforming techniques and regularised inverse methods have been tested over a set of coherent and incoherent sources. Results have been obtained which show that the beamformers are not able to accurately locate the sources when these are highly correlated or in the low frequency range. However, above a certain frequency threshold, it does not seem to be limited by the axial separation distance. On the other hand, although the inverse method is limited at low frequencies and in the far field, it allows the reconstruction of source strengths amplitudes. Under certain conditions, both methods can be used in a complementary way for a complete source characterisation.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p310.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p784" class="affilation"></a>Acoustic Antenna Design General Guidelines for Beamforming Noise Source Localization</h2>
<h3>Vincenzo Quaranta (1), Ignazio Dimino (1), Gaetano D’Altrui (2)</h3>
<p class="affilation">(1) CIRA, Italian Aerospace Research Centre, Via Maiorise 80143 Capua (CE), Italy (2) D’APPOLONIA, Engineering and Consulting Company, Via Paolo di Dono 223, 00142 Rome, Italy</p>
<p><b>ABSTRACT</b><br>
The design criteria of phased microphone array for moving sound sources localization and tracking by using beam-forming techniques are presented. A detailed analysis on how to evaluate the main array characteristics (microphones layout, number and spacing, antenna shape and dimension) from the requested performance (maximum range, angular resolution, maximum and minimum target sound frequency) has been carried out in order to give all the elements necessary to properly design the acoustic antenna. A dedicated code has been developed within MATLAB environment with a user friendly graphic interface. Starting from the acoustics requirements of the array transducers, the code allows the design of the antenna and evaluates the main array characteristics, also showed with comprehensive graphical outputs. Different arrays have been designed and analyzed. The study carried out in this work is a preliminary investigation necessary to estimate the costs and the reliability of such methodology for the realization of an acoustic antenna for far field noise source localization.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p784.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p465" class="affilation"></a>Noise Evaluation in a Race-Track: Measurements, Software Analyses and Need of Continuous Monitoring. Comparison Among the Results.</h2>
<h3>Anna Magrini (1), Andrea Cerniglia (2), Mariagiovanna Lenti (2), Lucia Cattani (3)</h3>
<p class="affilation">(1) Dept. of Environmental and Hydraulic Engineering, University of Pavia, Via Ferrata 1, 27100 Pavia, Italy (2) 01dB Italia, Via R.Sanzio 5, 20090 Cesano Boscone (MI), Italy (3) Engineering Faculty, University of Bergamo, Viale Marconi 5, 24044 Dalmine (BG), Italy</p>
<p><b>ABSTRACT</b><br>
Noise pollution caused by the activities in a race-track can affect wide spaces. First steps towards a reduction of noise levels are afforded by the international sport organisations that admit only silenced super-bikes in the competitions and that have put further reduced noise emissions requirements starting from the end of 2007. An experimental analysis on a racing track approved for international racings was performed with the circulation of various kinds of racers. After the calibration by means of measured data, the software model simulations of various race conditions were analysed. The results were compared with the experimental monitoring performed by a recently developed system that permits to register and to send directly all the results to a remote server in real time. The analysis has highlighted on one side some situations of exceeding noise that can be detected only by a continuous monitoring, on the other side the conditions in which the track can be used without overcoming limiting values. The noise maps taken by the software simulations have highlighted suffering conditions in some critical points around the track. The noise propagation investigation represents the basis of the noise pollution reduction studies performed to reach the best conditions in the surroundings of the race-track. Acoustic barrier attenuation, ground and vegetation absorption, better track configuration (bend, straights, etc) can be considered in the software simulations and analyses to compare the efficacy of the noise reduction measures.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p465.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p781" class="affilation"></a>Traffic Noise Abatement by Means of Acoustical Barriers: An Example of Reliability of Prediction Models with Different Kind of Barriers and Different Context</h2>
<h3>Franca Conti</h3>
<p class="affilation">Freelance engineer, Italy</p>
<p><b>ABSTRACT</b><br>
This paper synthesises a longer work written to verify the noise protection obtained with three different kinds of acoustical barriers (steel acoustic fencing, tile acoustic barrier integrated to the building, mass gravity gabion walls) in three different inhabited contexts. The problem was due to the presence of a very busy road or railway in each context analyzed: the first one was in Reggio Emilia, with building less than 5 meters away from the road; the second one was a case of a new building so close to the railway that it was impossible to build up a traditional barrier so to integrate it to the new building itself; the third one was in a rural area with a few houses all around. The research was based on an accurate experimental study of traffic noise both before and after the intervention: it required a large amount of human and instrumental resources, but it was possible to correctly establish the dimension and the materials of the barriers protecting people living close to the road. A numerical model (ray tracing plus mirror image), based on the algorithm ISO 9613, was implemented and used both for the analysis of the initial situation and for the design of noise barrier. The aim of the study was to design an acoustical barrier in order to guarantee compliance with the noise limit for that area type, according to Italian legislation, but the last step was the acoustical test of the barrier and it gave the same results as calculated with the model.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p781.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p281" class="affilation"></a>Local Ship Vibrations - A Methodology for Their Evaluation and Control from the Early Design Phase</h2>
<h3>Ottavio Pinto, Cesare Tarditi</h3>
<p class="affilation">FINCANTIERI, Naval Vessel Business Unit, Hydrodynamic and Acoustic Department, Via Cipro 11, 16129 Genoa, Italy</p>
<p><b>ABSTRACT</b><br>
Local Vibrations represent one of the most critical parameters for the comfort evaluation on board of the ship. Normally a limit value of vibration is defined in the ship specification and the shipyard has the responsibility to assure that the specified values are not exceeded. Depending mainly on the extension, vibration phenomena could be divided in Global Hull vibrations and local vibrations. Hull vibrations interest all the ship as a beam in its natural modes; local vibrations interest only parts of the ship. Local and Global vibrations could be studied and controlled modelling the ship with FEM 3D model in an advanced design phase, but Global and Local Vibrations could also be investigated in an early design phase when the ship is not yet modelled, with simplified models. The paper presents a methodology, developed by Fincantieri and experimentally tested on previous constructions, for the risk evaluation of local vibration exceeding the limit curve due to the main machinery excitations. Starting on the assumed machinery excitation spectra and depending on the their distance from main ship spaces, on the characteristics of the elastic connections, and on the type of structures, an evaluation of the deck vibrations amplitude is obtained. On the base of these data, when a risk of excess is noted, a deeper analysis on the evaluation of the deck natural frequency could be made in order to investigate more in detail the risk of resonance and in case of coincidence between the main machinery excitation and the natural frequency, structural countermeasures shall be taken.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p281.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p594" class="affilation"></a>A Cepstrum-Based Method for Remote Train Detection</h2>
<h3>Carlos F. Carvalho</h3>
<p class="affilation">Instituto Superior de Engenharia de Lisboa, Instituto Politélcnico de Departamento de Engenharia de Electrónica e Telecomunicações e de Computadores, Rua Conselheiro Emídio Navarro, 1 P-1950-062 Lisboa, Portugal</p>
<p><b>ABSTRACT</b><br>
On the subject of remote train detection, previous work has already been made, applying different techniques. The system described in this paper, comprises both hardware (receiver circuit connected to an accelerometer) and software subsystems. The latter subsystem employs a technique based on vector quantization (VQ). Through a training process, two centroids have been derived, resulting from the application of an unsupervised learning algorithm (Lloyd algorithm), using a 20th-order Cepstral analysis. Each centroid represents one of two different classes of signals: “Silence” (or absence of a moving train) and “Moving train” (approaching or withdrawing). What is being presently proposed is an alternative to a previous representation of the centroids, in which they were derived from a 14th-order Linear Predictive Coding (LPC) analysis. Similarly, incoming signals coming from the receiver must also undergo a Cepstral analysis. The input of the software subsystem consists of samples of the input signal, obtained by the hardware subsystem. Sampling rate is 16,000 samples per second, being the samples windowed into 300 ms frames, with a window displacement of 100 ms. The recognition (or classification) process is based on a distance measure to each one of the two centroids. The Euclidean vector distance measure was used for this purpose. Collected data was divided into training and classification corpora, respectively 67% and 33%. There were considered situations in which one had trains running on the same track where the receiver is connected to, and trains running on neighbour tracks, being the vibrations transmitted through the ground to the receiver circuit. For both situations, classification results are presented and discussed, comparing performances between the Cepstrum-based and the LPC-based pattern matching processes.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p594.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p728" class="affilation"></a>Binaural Cepstrum Coefficient and its Application to Ground Target Recognition</h2>
<h3>Luyang Guan, Ming Bao, Xiaodong Li, Jing Tian</h3>
<p class="affilation">Institute of Acoustics, Chinese Academy of Sciences, Beijing 100080, China</p>
<p><b>ABSTRACT</b><br>
Stereausis is a biologically motivated model proposed by Shamma which encodes both binaural and spectral information in a unified framework to simulate the processing of human binaural auditory system. In this paper, a new type of cepstrum coefficient is proposed based on this model. Two-channel acoustic signals are first processed by the stereausis binaural model to synthesize the spectral information and reduce the interference of noise signal. The binaural cepstrum coefficient is then extracted based on the diagonal vector of the stereausis model’s output pattern, and is applied as feature to the multi-class acoustic target recognition. Learning Vector Quantization (LVQ) algorithm is implemented as the classifier and is tested by samples of vehicle acoustic signals. Experimental results show that binaural cepstrum coefficient improves both the performance and generalization of the classifier, especially at low SNR.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p728.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p450" class="affilation"></a>Contrast Function Based Fourth-Order Statistics and Wiener Filtering for Separation of Convolutive Mixtures</h2>
<h3>Moussa Akil (1,2), Christine Servière (1), Robert B. Randall (2)</h3>
<p class="affilation">(1) GIPSA-lab, DIS Department, INPG - CNRS 961 Rue de la Houille Blanche, 38402 Saint Martin d’Hères, France (2) School of Mechanical and Manufacturing Engineering, University of New South Wales Sydney, NSW 2052, Australia </p>
<p><b>ABSTRACT</b><br>
In this paper, we consider the problem of blind separation of sources mixed by a convolutive system, expressed in the time-domain. We present a method based on fourth-order statistics and Wiener filtering. The technique is based on the minimization of two criteria based on the cancellation of the fourth-order cross cumulant between the contributions of all the estimated sources on each sensor, calculated by Wiener filtering. The matrix separation is updated iteratively by the contributions of the outputs recovered by Wiener filtering. These contributions are inserted in the separation procedure in order to get high separation quality of the data. Finally, simulation results illustrate the validity of our approach and show that it leads to improved separation performance.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p450.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p526" class="affilation"></a>Limitations and Error Analysis of Spherical Microphone Arrays</h2>
<h3>Thushara D. Abhayapala, Michael C. T. Chan</h3>
<p class="affilation">Research School of Information Sciences and Engineering, Australian National University, Canberra ACT 0200 Australia</p>
<p><b>ABSTRACT</b><br>
There has been a strong interest in theory and design of spherical microphone arrays in recent years due to their possible use in recording directional sounds for surround sound creation. The theory of such arrays is based on decomposition of sound fields to spherical harmonics which are the natural basis functions for valid sound fields over three dimensional space. However, due to physical size of practical spherical arrays, number of extractable spherical harmonic components are limited to the third order. This paper investigates the various design issues including the inherent limitations of the spherical microphone, discretization of the theoretical continuous spherical microphone into a microphone array and associated spatial aliasing problems, calibration errors of these microphones and signal processing issues. A fourth order microphone design was presented and analysed, which allowed the verification, integration and evaluation of the design issues mentioned earlier, in the context of this design. Overall, the design was capable of recording a frequency range of [340; 3400] Hz. The work presented in this paper has made the following main contributions to sound field recording: (i) Analysis of the role of rigid spheres in improving microphone design; (ii) Analysis of various microphone arrangements, which are applicable to microphone array design; (ii) A model for analysing the error due to inexact positioning of microphones in a spherical array; (iii) A set of error measures for error analysis of spherical microphones; and (iv) Design and analysis of a fourth order spherical microphone.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p526.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p778" class="affilation"></a>Application of Cepstrum Analysis in Speech Coding</h2>
<h3>Vahid Abolghasemi, Hossein Marvi</h3>
<p class="affilation">Faculty of Electrical & Robotic Engineering, Shahrood University of Technology, Iran</p>
<p><b>ABSTRACT</b><br>
A simple Code Excited Linear Prediction Coder based on Cepstral-Analysis to decrease the bit-rate of coder has been proposed. The proposed method first applies Cepstral analysis to the input speech signal and then attempts to remove insignificant coefficients of the cepstrum. These modified coefficients rather than the input speech samples, are fed to our simple CELP coder to be encoded. At the decoder side, we compute inverse cepstrum of the decoded coefficients and obtain the reconstructed speech signal. Our experimental results approve the reduction of bit-rate.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p778.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p510" class="affilation"></a>Non-Uniform, Harmonic, Edge Excitation of a Waveguide</h2>
<h3>Baruch Karp</h3>
<p class="affilation">Faculty of Aerospace Engineering, Technion - Israel Institute of Technology, Haifa 32000, Israel</p>
<p><b>ABSTRACT</b><br>
The plane strain response of a semi-infinite, elastic strip to harmonic, symmetric, and non-uniform end excitation is investigated analytically. The solution is obtained as a series expansion of the Rayleigh-Lamb modes of the strip. The variation of the energy partition among the propagating modes with the frequency of the end excitation was found for mixed end conditions prescribed at the excited end (load and displacement types). The bi-orthogonality relation was employed in deriving the relative amplitudes of each mode to the given excitation. It was found that the far field response of the strip is largely indifferent to whether the excitation is a displacement or stress type. The previously reported phenomenon of the existence of one dominating wave in uniform excitation is shown to extend to moderately non-uniform excitations as well. The phenomenon of complete dominance of one mode for generally non-uniform excitations was exposed.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p510.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p176" class="affilation"></a>Linear Sources with Non-Linear Distribution of Sound Energy</h2>
<h3>Miroslav Kučera, Richard Nový, Jiří Bašta</h3>
<p class="affilation">Czech Technical University in Prague, Faculty of Mechanical Engineering, Department of Environmental Engineering, Technická 4, 166 07 Prague 6, Czech Republic</p>
<p><b>ABSTRACT</b><br>
In practical circumstances we often meet sources the structures of which approach those of current HVAC ducts but with dimensions and mode of radiation completely different. Typical are light stacks of factories, refuse incinerating plants, etc. The core of the problem is that a stack must be considered as a linear source where sound power is radiated in two parts. The first is the top of the stack (point source) and the second, considerably greater, is the outer surface of the stack (linear source). Sound power, however, is radiated by the outer surface of the stack in a non-linear mode and drops from the flue gas inlet to the top of the stack. In projects it is therefore very difficult to predict how a stack radiates sound energy, in order to avoid exceeding hygienically permissible limits. This paper deals with ducts with walls made of relatively thin sheets.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p176.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p616" class="affilation"></a>Direct Algebraic Method for Sound Source Localization with Finest Resolution Both in Time and Frequency</h2>
<h3>Shigeru Ando, Nobutaka Ono, Takaaki Nara</h3>
<p class="affilation">Department of Information Physics and Computing, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan</p>
<p><b>ABSTRACT</b><br>
We deal with the problem of direction and distance estimates of sound sources in 3-D space and arrive at a new exact and direct algorithm from finite observations both in space and time. We first derive a partial differential equation (PDE) which we call the sound source constraint (SSC). We show that the general solution of the SSC-PDE is a diverging spherical wave from a point source with arbitrary temporal waveform. The SSC enables the observer to determine the source location (distance R and direction n) from local measurements of the wavefield. For the measurements of wavefield, we consider weighted temporal integrals of arrayed microphone outputs in a finite duration.We obtain exact formulae for localizing a single source from single weight measurements and multiple sources from the combination of differently weighted measurements. We examine the performance by simulating non-stationary complex multi-source environments.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p616.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p5" class="affilation"></a>Areas of High Acoustic Quality: Soundscape Planning</h2>
<h3>A. L. Brown</h3>
<p class="affilation">Griffith School of Environment, Griffith University, Nathan, Brisbane, 4111, Australia</p>
<p><b>ABSTRACT</b><br>
This paper develops ideas on moving “soundscapes” into the mainstream of activity of environmental noise. Such a move has value in introducing a new dimension aimed at catching political attention and the engagement of other professions in acoustic management of outdoor environments. “Quiet Areas” - the EU Directive on Environmental Noise requires “preserving environmental noise quality where it is good”. The paper shows contrasts and similarities between conventional noise control approaches with those in the soundscape literature. Environmental noise control deals with sounds of discomfort; soundscapes sounds of preference. Noise control measures sound by integration; in soundscapes the information content of sound is critical. Noise control manages sound as a waste product; soundscapes manages sound as a scarce resource. Managing “quiet areas” is about managing the resource of high quality acoustic environments. “Quiet” is not always (even rarely) their characteristic - instead we should adopt the terminology “areas of high acoustic quality”. There is enough evidence to discount standard noise criteria (say L<sub>eq</sub> or L<sub>den</sub>) as criterion for such areas. Instead, a two- dimensional criterion is needed: level of sound (high level sounds versus low level sounds) and distinction between sounds that are unwanted and sounds that are wanted in particular contexts.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p5.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p455" class="affilation"></a>Change in Quality of Environmental Sound in the Autumn</h2>
<h3>Hideo Shibayama</h3>
<p class="affilation">Shibaura Institute of Technology, 3-7-5 Toyosu, Koutou_ku Tokyo, 135-8548 Japan</p>
<p><b>ABSTRACT</b><br>
In rural suburbs, there were, in the past, many birds, insects and other sources of life, particularly near tiny streams. There was pleasure in listening to their singing, and in observing their actions in this natural environment. However this natural environment is changing, and more monotonous scenery is replacing it. Once housing has been developed, and roads constructed, it is difficult for the natural life to continue to live in the new environment. Consequently it is difficult to find the specific kinds of insects that used to inhabit the area. There are very few records of the environmental sound from these earlier times. Even though the environmental sound levels are high, due to their singing, many Japanese enjoy the sound and do not class it as unwanted noise. We show the frequency characteristics of the environmental sound for this measurement period.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p455.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p193" class="affilation"></a>Analysis, Design and Fabrication of MEMS Capacitive Microphones</h2>
<h3>Hong-Ching Her (1), Chuan-Hsien Cheng (2), Hsien-Kuang Liu (1), Jin H. Huang (1)</h3>
<p class="affilation">(1) Department of Mechanical and Computer-Aided Engineering, Feng Chia University, Taichung 40724, Taiwan (2) Merry Electronics Co., Taichung Industrial Park, Taichung 407, Taiwan</p>
<p><b>ABSTRACT</b><br>
Condenser microphones with considerably higher sensitivity and low power consumption offer an innovative design for sound pressure micro sensors. Polysilicon with smooth surfaces and incredibly by low residue stress is used for the diaphragm of the capacitive microphone. Two methods - equivalent circuit method and finite element method - have been applied in this research to achieve the highest sensitivity of the capacitive microphone. Optimal parameters, such as the dimension of the diaphragm, the air gap distance, the volume of front and back chambers, and the hole fraction in the backplate, have been determined through analyzing and simulating the MEMS condenser microphone, understanding the variation of parameters, and dissecting the impact among sensitivity, frequency response and electric field. Consequently, the valuable design parameters are able to be provided for the best choice of condenser microphones among different materials. In addition, the results can improve and control the performance and dimensions of the microphone. Furthermore, the microphone is fabricated using a combination of surface and bulk micromaching techniques which has the favourable integrated capability of CMOS (Complementary Metal-Oxide Semiconductor). The device and techniques are promising for their future production.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p193.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p709" class="affilation"></a>Urban Transport and Noise Impact: A Preventive Applied Research to Control Noise Impact of New Road to be Build in Catania Province</h2>
<h3>Francesco Patania, Antonio Gagliano, Francesco Nocera, Aldo Galesi, Antonio D’Amico</h3>
<p class="affilation">Energy and Environmental Division of D.I.I.M., Catania University of Engineering, A.Doria 6, 95125 Catania, Italy</p>
<p><b>ABSTRACT</b><br>
Building a new road means for the country a socioeconomic growth indeed but, in the other hand, could produce negative impact on environment crossed because of noise emissions coming from motor vehicles running. On this ground an applied research has been carried out both to forecast and to control future acoustic negative effects that could be originate by provincial road “S.P. Misterbianco-Nicolosi” already in last stage of plane. Research has been carried out not only to evaluate any eventual disturbs on the people living in the borders of road but as well as to verify the respect for current Italian regulations about noise pollution. Campaigns of measurement of Leq(A) “ante operam” have been done to validate the calculation codes utilized for such an outdoor environment full of anthropic and natural obstacles to noise diffusion. Therefore paper wants to show:<ul> <li>results of campaigns of acoustical measurements;</li> <li>techniques and models of sound diffusion used for forecasting of noise “post operam”;</li> <li>comparison of results of forecast with that ones Leq(A) limits of reference to Italian noise regulations;</li> <li>protections works designed to mitigate Leq(A) one higher than that permitted by regulations.</li> </ul></p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p709.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p673" class="affilation"></a>Frequency Dependence in Tyre-Road Emissions Using the Close Proximity Method</h2>
<h3>Gaetano Licitra (1), Mauro Cerchiai (2), Luca Teti (2), Luca Nencini (2)</h3>
<p class="affilation">(1) A.R.P.A.T.- Environmental Protection Agency of Tuscany Region - Via N. Porpora, 50144, Florence, Italy (2) A.R.P.A.T.- Environmental Protection Agency of Tuscany Region - Dept. of Pisa - Via Vittorio Veneto, 56127 Pisa, Italy</p>
<p><b>ABSTRACT</b><br>
In the context of a Regional project about the characterization of existing road pavements and the study of new types of pavement mixtures, a study concerning the optimization of the acoustical features of the road surface has been performed. Several measurement techniques were used in order to describe the acoustical properties of the existing pavement surfaces, such as the Close Proximity Method. Data analysis shows that the correlation coefficients between equivalent sound level and vehicle speed are frequency dependent. They were calculated in the frequency range between 315 and 8000 Hz and they change in a considerable way, following the pavement roughness and porosity . In this work is proposed a method to characterize the pavement in a more complete way with respect to the formula given in the ISO/CD 11819-2 which doesn’t take in to account the frequency dependence in tire-road emission levels. Furthermore the variability of the noise levels depending on the length of the sampled segments of the road has been analysed.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p673.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p499" class="affilation"></a>Repeatability of CPX Tyre/Road Noise Measurements</h2>
<h3>Gillian Adams, Frits Kamst, Stephen Pugh</h3>
<p class="affilation">ASK Consulting Engineers, Brisbane, Australia</p>
<p><b>ABSTRACT</b><br>
Road traffic is the main source of environmental noise in Australia due to the extensive road network and the tendency for people to be located near major roads. The main component of road traffic noise is caused by the interaction of the road surface and the vehicle tyres for speeds in excess of approximately 60 to 70 km/h. A CPX (Close Proximity Method) dynamic test rig has been developed and tested to measure the road/tyre interaction noise using the CPX method outlined in committee draft ISO 11819:2. Testing has previously been undertaken to show compliance of the CPX test rig with the certification procedures in ISO 11819:2. The certification test procedures assess the capability of the CPX test rig to shield measurement equipment from other noise sources while approximating a free field environment in a semi-enclosed chamber. In addition to the certification tests, ISO 11819:2 nominates theoretical repeatability values for the measurement procedure. Potential impacts on the repeatability include temperature, test tyre load, equipment set-up and calibration, and accurate location of the test section of road. The intent of recent testing is to gain an understanding of the influence of these impacts and to demonstrate the measurement repeatability of the CPX ‘ROAD EAR’ test rig. This study includes a review of the test data and a comparison of the test data with the ISO nominated repeatability values.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p499.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p173" class="affilation"></a>Modified Tire-Pavement Noise Measurement Techniques for Noise Assessment on Asphalt-Rubber Roads</h2>
<h3>Huay Seen Lee, Liming Dai</h3>
<p class="affilation">Industrial Systems Engineering, University of Regina, 3737 Wascana Parkway, Regina, Saskatchewan, S4S 0A2, Canada</p>
<p><b>ABSTRACT</b><br>
This paper investigates the availability of recognized standards for measuring tire/pavement noise by determining the existence of a common or certified standard in measuring ARC road noise. The possibilities for establishing a common standard or making enhancements to the current standards for accurately measuring traffic noise in North America are also studied. Two different noise measurement studies are conducted on both conventional and ARC roads. The noise measurement study is based on the Statistical Pass-by method per International Standards Organization ISO 11819-1 while the other measurement study is based on the Close-Proximity Method based on International Standards Organization ISO 11819-2. Modifications have been made to the noise evaluation techniques in order to suit the local environment during measurements. The paper focuses on the advantages and disadvantages of implementing both noise measurement methods. Theoretical calculations are incorporated in order to the estimate the noise level errors during measurement. Simulations are performed to determine the influence of the receivers’ distance on the accuracy and reliability of the test measurements. Comparisons and recommendations are made for both methods under different measurement conditions and requirements.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p173.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p273" class="affilation"></a>Noise Source Identification of Korean High Speed Train</h2>
<h3>Hyoin Koh, Wonhee You, Hyukbin Kwon, Donghyung Lee</h3>
<p class="affilation">Vehicle dynamics research team, railway system and safety research department, Korea Railroad research Institute, #360-1, Woram-Dong, Uiwang-City, Gyeonggi-Do, Korea, 437-757</p>
<p><b>ABSTRACT</b><br>
This paper deals with the noise source identification of the Korean High Speed Train (KTX) at the maximum commercial speed of 300 km/h. Typical pass-by noise sources and their frequency characteristics are investigated, it is primarily aimed at investigating the location and characteristics of the low frequency noise (60 Hz ~ 100 Hz) related sources, however. This low frequency range noise has become an issue in the interior of the KTX, especially at passing through the tunnels with slab track system. For the purpose of identifying the main noise sources the results from the microphone array tests are analyzed in relation to the remarks from analytic studies which have been done with the intention of understanding the aerodynamic source mechanism and rolling mechanism. The acoustical image shows the low frequency noise sources mainly at the position of the under part of the train and the related source mechanism are discussed.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p273.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p720" class="affilation"></a>Regulation of Heavy Vehicle Engine Brake Noise in Australia</h2>
<h3>Jeffrey Parnell (1), Bruce Dowdell (2)</h3>
<p class="affilation">(1) NSW Dept. of Environment and Climate Change, PO Box A290 Sydney South, NSW 1232, Australia (2) NSW Roads and Traffic Authority, 260 Elizabeth St, Surry Hills, NSW 2010, Australia</p>
<p><b>ABSTRACT</b><br>
Engine brake noise is a long standing issue both in Australia and overseas with it being generally accepted that it is the character of this noise rather than its loudness that leads to most complaints. To date, the majority of the investigation and research into engine brake noise, and possible solutions, has been commissioned by Australian road agencies. There is now sufficient research in Australia, and agreement from all stakeholders, that action must be taken to provide a foundation for in-service regulations to control excessive engine brake noise. This paper describes the process being followed to achieve scientific acceptance of a method to identify excessively noisy engine brakes and its passage towards regulation in Australia. Steps in progressing this method have included developing a Modulated RMS algorithm that was capable of: <ul><li>discriminating between annoying and less annoying engine brake noise;</li> <li>discriminating between muffler effectiveness;</li> <li>correlating well with the subjective response of panel members to engine brake noise;</li> <li>being coded in software so that large amounts of roadside noise data can rapidly</li> analysed.</ul></p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p720.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p503" class="affilation"></a>Novelty Detection of Radar Signal Using Support Vector Data Description</h2>
<h3>Jong-Bok Lee (1), Dae-Sung Kang (1), Yun-Hyun Cho (2), In-Beom Yang (3), Hoon Heo (4)</h3>
<p class="affilation">(1) Department of Control and Instrumentation, Korea University, Seoul, 136-701, Korea (2) Shin-Ho Systems, Kyunggi-Do, Korea (3) KATECH, Chonan, Korea (4) Department of Control and Instrumentation, Korea University, Seoul, 136-701, Korea</p>
<p><b>ABSTRACT</b><br>
Recently it becomes safer and comfortable to drive a car owing to rapid progress of electronic device. One of the intelligent transportation systems (ITS), cruise control, is developed to assist driver. Cruise control is a system that maintains fixed distance and velocity against proceeding car. In cruise control system, it is important to reduce the irregular noises in RADAR signal. Corrected RADAR signal is important parameter to maintain distance and velocity in driving a car. The car with a built-in cruise control system can avoid a rear-end collision using RADAR signal. Noisy signal in cruise control system may lead rear-end collision with proceeding car. In the study, SVDD (Support Vector Data Description) technique is utilized to determine whether the RADAR signal is correct or not. Also abnormal condition of RADAR sensor can be confirmed via the technique.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p503.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p655" class="affilation"></a>The Contribution of the Individual Sound Source Generated from Shinkansen Vehicles</h2>
<h3>Kaoru Murata, Kiyoshi Nagakura, Toshiki Kitagawa, Akio Sagawa</h3>
<p class="affilation">Noise Analysis Group, Environmental Engineering Division, Railway Technical Research Institute, 2-8-38, Hikari-cho Kokubunji-shi, Tokyo, Japan</p>
<p><b>ABSTRACT</b><br>
For the prediction of the wayside noise level it is important to comprehend contribution of individual sound source in detail at a measurement point. First, the power level of individual sound source generated from Shinkansen vehicles were estimated by a field test using an acoustic mirror. Next, an acoustic experiment with 1/25 scale models was conducted to investigate the insertion loss of sound barriers for each sound source position. On the basis of the results of the field test and the acoustic experiment, the contributions of the individual sound source to the wayside noise level were estimated when the Shinkansen vehicles run on a viaduct with sound barriers.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p655.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p798" class="affilation"></a>Acoustic Properties of Sound Barriers</h2>
<h3>Mihai Bugaru, Raluca Dale</h3>
<p class="affilation">Department of Mechanics, University Politehnica of Bucharest, Bucharest, Romania</p>
<p><b>ABSTRACT</b><br>
The purpose of this study was to optimize the acoustic properties of sound barriers for traffic noise applications. For a correct assessment of the noise produced by road vehicles, it is necessary to know every detail about the noise source. The main difficulty in the prediction of road traffic noise levels is the great variation in source conditions. First of all, the road vehicle type may vary from scooters and mopeds to various types of passenger cars to various types of trucks. Secondly, the characteristics of the road surface are of great influence on the tyre/road noise production. Finally, the noise produced by a single vehicle on a specific road surface is dependent on driving behavior and meteorological conditions.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p798.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p181" class="affilation"></a>A Model of the Wear Due to the Rolling Contact of a Wheel Over a General Rail Profile</h2>
<h3>P. A. Bellette, P. A. Meehan, W. J. T. Daniel</h3>
<p class="affilation">Rail CRC, School of Engineering, University of Queensland, Brisbane, QLD 4072, Australia</p>
<p><b>ABSTRACT</b><br>
Recent research has suggested that the contact mechanics between the wheel and rail in railway systems may act as a geometric filter for wear-type rail corrugation. This filter is hypothesized to work alongside the dynamics to create the wear pattern, attenuating some wavelengths (and associated frequencies) while promoting others, and hence influencing the spectra of noise produced. It has been proposed that this effect may give rise to the field observation of the speed insensitivity of the dominant wavelength of short pitch corrugation. This type of corrugation is responsible for an annoying tonal noise in the range of 500-800 Hz. In this paper a simplified model of the wear due to the rolling contact of a wheel over a general rail profile is presented. This model is simple to implement and allows for an investigation into the non-linear behaviour of the dynamic wear, not discussed in previous research. The relevance of these results to the transportation noise phenomenon of wear-type rail corrugation is discussed.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p181.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p182" class="affilation"></a>A Case Study on the Effect of Speed Variation on the Growth of Wear-Type Rail Corrugation </h2>
<h3>P. A. Meehan, P. A. Bellette, W. J. T. Daniel, R. J. Horwood</h3>
<p class="affilation">Rail CRC, School of Engineering, University of Queensland, Brisbane, QLD 4072, Australia</p>
<p><b>ABSTRACT</b><br>
The transportation noise phenomenon known as wear-type rail corrugation is a significant problem in railway engineering, which manifests as an undesirable periodic wear pattern on the contact surfaces of the rail. This variation from a flat profile induces unwanted vibrations, noise and other associated problems. Currently the only reliable solution to corrugation is removal by grinding at significant expense to the railway operator. Recent research by the current authors has theoretically shown that uniformity in pass speed enhances corrugation growth rate and that broadening the probabilistic pass speed distribution may be a possible method of mitigating corrugation growth. To further test these results and to quantify the expected performance, in this paper, field measured data from a site with recurrent corrugation is used to tune and validate a theoretical model that predicts the growth rate of the phenomenon. The effect of changing the field measured pass speed distribution is then investigated and results quantifying the expected reduction in corrugation growth rate are presented and discussed.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p182.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p653" class="affilation"></a>Comparing Weekly and Weekday Averaged Traffic Data When Modelling Traffic Noise</h2>
<h3>Peter Karantonis (1), David Gonzaga (2)</h3>
<p class="affilation">(1) Renzo Tonin & Associates (Qld) Pty Ltd, L20, 300 Queen Street, Brisbane, QLD, 4000, Australia (2) Renzo Tonin & Associates (NSW) Pty Ltd, L1, 418a Elizabeth Street, Surry Hills, NSW, 2010, Australia</p>
<p><b>ABSTRACT</b><br>
Generally road noise policies, guidelines and standards in Australia either, do not specify what traffic conditions should be used or there are inconsistencies in what is specified for use in noise impact assessments. As a consequence, acoustic consultants tend to use 7-day (Monday to Sunday) averaged traffic data (from Annual Average Daily Traffic, AADT data) when conducting noise assessments rather than 5-day (Monday to Friday) weekday averaged traffic data (from Annual Average Weekly Traffic, AAWT data). For many arterial roadways (eg motorways, freeways, highways etc) weekend traffic flows tend to be lower than weekday traffic flows, often with lesser heavy vehicles on the road on weekends than on weekdays. Therefore, the question raised on recent road projects is, should 5-day data be used in lieu of 7-day data? The premise behind this question is that 5-day averaged traffic results would better represent the true noise impacts affecting communities than 7-day averaged results. This is because it is considered, by some, that averages over 7-days could potentially ‘water-down’ and understate the true noise impacts from a road. This paper investigates this issue by using actual traffic volume and composition data from over 500 different metropolitan and rural arterial roads and sub-arterial roads in various states throughout Australia to carry out noise modelling to compare results and test this premise. This paper also comments on the significance of the difference in impacts in terms of the final reported noise levels, how this may affect the design and selection of road noise mitigation and whether or not this would make a real difference in noise impacts affecting the community.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p653.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p2" class="affilation"></a>A Recent Investigation into the Influences of Some Australian Asphalt Pavement Surfaces on Road Traffic Noise</h2>
<h3>Stephen Samuels (1), Jeff Parnell (2)</h3>
<p class="affilation">(1) TEF Consulting and School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW 2052, Australia (2) Department of Environment and Climate Change, PO Box A290 Sydney South, NSW 1232, Australia</p>
<p><b>ABSTRACT</b><br>
This paper deals with an investigation into the influences of some Australian asphalt pavement surfaces on the generation of road traffic noise. The investigation represents a recent component of an ongoing pavement surface noise research program in which both authors have been involved over several years. It focused on the roadside noise produced by a passenger vehicle travelling under controlled conditions on a set of asphaltic pavement surfaces that are typical of those adopted in the states of New South Wales and Queensland and, indeed, elsewhere throughout Australia. Results of the investigation, which are summarised in the paper, demonstrated that there is a considerable degree of variability in the acoustic attributes of the pavement surfaces studied. Interpretations and explanations of this variability are offered in the paper. Moreover, the outcomes of the investigation were compared with the acoustic attributes of sets of nominally similar and different pavement surfaces constructed in other countries and which had been previously reported in the open literature. Explanations for the similarities and differences between the acoustic attributes of the Australian and overseas asphalt pavement surfaces are also offered in the paper.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p2.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p321" class="affilation"></a>Characteristics of Aerodynamic Noise from the Inter-Coach Spacing of a High-Speed Train</h2>
<h3>Sunghoon Choi (1), Hyoin Koh (1), Chan-Kyung Park (1), Junhong Park (2)</h3>
<p class="affilation">(1) Korea Railroad Research Institute, Woulam-dong, Uiwang-city, Gyunggi-do, 437-757, Korea (2) School of Mechanical Engineering, Hanyang University, Haengdang-dong, Seongdong-gu, Seoul, 133-791, Korea</p>
<p><b>ABSTRACT</b><br>
As the speed of high speed trains increases, the aerodynamic noise tends to dominate all other noise sources. Several measurements for high-speed trains in Korea confirmed that aerodynamically generated noise is significant when the train speed exceeds 250 km/h. This phenomenon becomes prominent in the low frequency range below 200 Hz, especially, when the train passes tunnels. It has a baneful influence upon interior noise because the sound insulation characteristic of the car-body structure is very weak in this low-frequency range. In this paper, experiments were performed in order to investigate the characteristics of aerodynamic noise sources generated from the inter-coach spacing of a high-speed train. It has been found that the low frequency noise is strongly dependent on the size of the inter-coach spacing that increases the turbulent intensity of the flow along the train surface and also inside the cavity. These pressure fluctuations excite the train structure which in turn radiates noise inside the passenger cabin. Measurements of both the inside and outside of the cabin are carried out to investigate the characteristics of the noise. Also performed is an array measurement to locate different noise sources from the high-speed train. Finally efforts have been made to reduce the interior noise level by varying the width of mud-flaps, rubber curtains used to prevent inter-coach components from contamination, and the results show significant decrease in the interior noise for the optimized width of mud-flaps.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p321.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p732" class="affilation"></a>Noise Characteristics of an Exposed Aggregate Cement Concrete Surface</h2>
<h3>Ulf Sandberg</h3>
<p class="affilation">Swedish National Road and Transport Research Institute (VTI), SE-58195 Linkoping, Sweden, and Chalmers University of Technology, Division of Applied Acoustics, SE-41296 Gothenburg, Sweden</p>
<p><b>ABSTRACT</b><br>
On high-volume roads cement concrete surfaces may be economically favourable in compari-son to asphalt concrete. When a bypass for motorway E4 in Uppsala (Sweden) was built, cement concrete was therefore selected as the wearing course. It is well known that noise characteristics of cement concrete surfaces may be poor unless a suitable texture is created. Earlier, the Swedish Road Administration has used the exposed aggregate technique to create a favourable surface texture on newly laid cement concrete on some motorways in Sweden, with both good and poor results. This time a special aggregate grading of the top layer was selected, attempting to combine the desire to have excellent durability against the wear of studded tyres in winter, and the desire to limit tyre/road noise emission from the motorway. Being a bypass, this motorway at some locations run rather near to suburban areas where noise immission might become a serious issue. Noise measurements were made with the CPX method, using four test tyres. The results on the exposed aggregate cement concrete (EACC) were compared with similar measure-ments on SMA surfaces with the same maximum aggregate size. As a reference for com-parison three SMA 0/16 were chosen since this is the surface type that would normally be used on a motorway of this kind. The results indicated approx. 2-3 dB(A) lower tyre/road noise emission on the EACC than on the SMA 0/16 which was better than expected. In the paper the probable causes of the relatively low noise emission are analyzed. The positive results suggest that with a suitable proportioning of the aggregate in the surface layer and high quality exposure technique, the EACC may be used as a standard technique for texturing of cement concrete.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p732.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p421" class="affilation"></a>A Preliminary Study of Noise in a Tunnel Due to a Moving Train</h2>
<h3>W. S. Fung (1), T. L. Yip (1,2), S. T. So (1), G. H. Frommer (2), K. M. Li (3)</h3>
<p class="affilation">(1) Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hung Hom, Hong Kong (2) MTR Corporation, MTR Tower, Telford Plaza, Kowloon Bay, Hong Kong (3) Ray W. Herrick Laboratories, School of Mechanical Engineering, Purdue University, West Lafayette, IN 47907-2031, USA</p>
<p><b>ABSTRACT</b><br>
Citizens travelling between cities and towns rely heavily on a mass transport system in many developed countries. In recent years, many more of these underground railway systems are constructed and expanded in many different cities. Though there have been significant reductions in the acoustical environment in automobiles and aircraft, train passengers are only recently starting to see improvements. The prime purpose of this preliminary study is to estimate the noise levels due to an underground train operating at different speeds in a tunnel. A simple experimental method is explored for measuring noise levels of a passenger train travelling in a tunnel in urban areas. This paper also attempts to study the reverberant sound fields when a train operates inside a tunnel - a long enclosed space. The result of the current study provides a guideline for design engineers in their future planning for constructing a new railway line and assists in supporting realistic contractual specifications. The experimental results can also be used as a guide to direct future efforts for reducing noise levels transmitted into the passenger compartments for an existing railway line.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p421.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p669" class="affilation"></a>The Study of Vertical Distribution of Urban Road Traffic Noise</h2>
<h3>Wei Zhiyong, Zhu Yanyan, Song Ruixiang, Zhang Bin</h3>
<p class="affilation">Beijing Municipal Institute of Labour Protection, Beijing 100054, China</p>
<p><b>ABSTRACT</b><br>
Currently, traffic noise of urban road has serious effect on residents living beside the road. Because of the buildings beside urban roads, the vertical distribution of noise is complex. Sometimes residents living on high floor are affected seriously. For better control of traffic noise, it has real significance to study the vertical distribution of traffic noise. Through noises monitoring of road traffic in Beijing, we analyse and study the vertical distribution of high-rise buildings beside urban roads, and give the characteristics of road traffic noise attenuation with the vertical direction.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p669.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p642" class="affilation"></a>Ultrasound Piezoceramic Transducer for Underwater Acoustics in Sonochemistry</h2>
<h3>Irinela Chilibon (1), Mihaela Mocioi (2), Carmencita Mateescu (3)</h3>
<p class="affilation">(1) National Institute of Research and Development for Optoelectronics, INOE- 2000, PO Box MG-5, 77125, Bucharest-Magurele, Romania (2) University “Politehnica” of Bucharest, Bucharest, Romania (3) National Institute for Materials Physics, PO Box MG-7, Bucharest-Magurele, Romania</p>
<p><b>ABSTRACT</b><br>
The effect of ultrasound fields on reactive crystallization nucleation could produce homogeneous nucleation and improve the process reactivity into chemical solutions. Organic molecules or polymers can influence the crystallization of inorganic salts and may act as crystal growth inhibitors. It is not yet clear if the additive interacts with dissolved components or with the developing phase. Crystallization process may be controlled by various additives. Also, ultrasounds may also affect the process. Complex phenomena take place in liquids when an ultrasonic field is applied. Ultrasounds yield cavitation bubbles which accumulate gases and vapors from the liquid phase until they become too large and collapse, producing shock waves. The temperature and pressure inside the cavitation bubbles and in their vicinity are huge and influence all chemical reactions taking place in the liquid phase. Also, ultrasounds induce different reactions into the chemical mixed solutions, function of ultrasound duration, frequency, temperature, and application manner of solutions (dripping or pouring). Therefore a small size ultrasound piezoceramic transducer is suitable to the sonochemistry applications. The generation is made by a transducer supplied by a signal generator. The ultrasound piezoceramic transducer generates ultrasound field which yields caviational effects such as: enhancement of gas bubbles, temperature increasing, mechanical effects, dispersion of solids in liquids, and reactivity increasing. The transducer converts electrical signal into mechanical vibrations, which are propagated into chemical solutions. The small diameter of transducer case allows get to straiten glass tubes, such as the chemical flask necks. The ultrasound piezoceramic transducer is suitable to generate ultrasound in the same time with the chemical processes, at 46 kHz resonance frequency. A transducer application in sonochemistry process is the calcium carbonate crystallization, combining the effects of organic additives and ultrasonic field. As final result is calcium carbonate powder with large amount of nanometer size crystals.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p642.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p738" class="affilation"></a>Removal of Dust on Flat Board by Device of Focusing Ultrasonic Waves</h2>
<h3>Noritoshi Nakagawa, Yusuke Konishi</h3>
<p class="affilation">Department of Mechanical System Engineering, Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8527, Japan</p>
<p><b>ABSTRACT</b><br>
The rapid advancements in various current technologies and the constant trend in miniaturizing of components have created a need for higher cleanliness levels. Dust on the surface of IC components often affects their functions. Sometimes, it may damage the component. Therefore, the technology is necessary to remove effectively dust. In the present study, a vibration system, composed of a bolt-clamped Langevin transducer and a disc, was employed to study the effect of dust removal experimentally. When a flat board with calcium carbonate powder was irradiated by this focusing ultrasonic wave, the powder was diffused and removed completely. The experimental result indicates that: the higher input voltage of transducer, the higher removal efficiency.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p738.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p349" class="affilation"></a>Design Sensitivity Analysis of Zwicker’s Loudness Using the Adjoint Variable Method</h2>
<h3>Kunmo Koo, Semyung Wang, Daesung Kim, Chwail Kim, Daeil Kwon</h3>
<p class="affilation">School of Information and Mechatronics, Gwangju Institute of Science and Technology, 1 Oryong-dong, Buk-gu, Gwangju, 500-712, Korea</p>
<p><b>ABSTRACT</b><br>
A design sensitivity formulation of Zwicker’s loudness is presented using the adjoint variable method (AVM). The dynamic behaviour of a structure is analyzed by the frequency-response method. Acoustic pressure radiated from the vibrating structure is obtained by the Boundary Element Method (BEM). The global acoustic sensitivity is calculated using AVM, and the sensitivity of main specific loudness with respect to the design variables is obtained using the chain rule. The proposed sensitivity result is compared to finite difference sensitivity. It turned out that the computational time for calculating sensitivity is extremely reduced, and the sensitivity result is similar to the result of the finite difference method.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p349.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p811" class="affilation"></a>A Comparison of Structural-Acoustic Coupled Reduced Order Models (ROMS): Modal Coupling and Implicit Moment Matching Via Arnoldi</h2>
<h3>R. Srinivasan Puri (1), Denise Morrey (1), John F. Durodola (1), Rick C. Morgans (2), Carl Q. Howard (2)</h3>
<p class="affilation">(1) School of Technology, Oxford Brookes University, Oxford OX33 1HX, UK (2) School of Mechanical Engineering, University of Adelaide, SA 5005, Australia</p>
<p><b>ABSTRACT</b><br>
The calculation of the coupled response of a structure with an enclosed acoustic cavity is of great interest, with many practical applications in the automotive and aerospace industries. Traditional methods such as a fully coupled fluid-structure interaction finite element calculation can be very computationally expensive, and methods have been proposed that reduce this computational burden and make it possible to include iteration and optimisation in the design process. This paper compares the performance of two such reduced order model (ROM) methods, a traditional modal coupling technique and an implicit moment matching method via Arnoldi, with a fully coupled finite element calculation. A simple model, a square simply supported steel plate backed by a rigid walled cavity is used as an example, and the accuracy of each method is examined for both damped and undamped cases. It was found that Arnoldi gave excellent agreement with the fully coupled calculation, and that while modal coupling gave excellent agreement near resonance, the performance off resonance was dependent on the number of modes retained.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p811.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p184" class="affilation"></a>Accurate Measurement of Small Absorption Coefficients</h2>
<h3>A. F. Seybert, J. Han, D. W. Herrin</h3>
<p class="affilation">Department of Mechanical Engineering, 151 Ralph G. Anderson Building, University of Kentucky, Lexington, KY 40506-0503, USA</p>
<p><b>ABSTRACT</b><br>
In this paper procedures for estimating the sound absorption coefficient when the specimen has inherently low absorption are discussed. Examples of this include the measurement of the absorption coefficient of pavements, closed cell foams and other barrier materials whose absorption coefficient is nevertheless required, and the measurement of sound absorption of muffler components such as perforates. The focus of the paper is on (1) obtaining an accurate phase correction and (2) proper correction for tube attenuation when using impedance tube methods. For the latter it is shown that the equations for tube attenuation correction in the standards underestimate the actual tube attenuation, leading to an overestimate of the measured absorption coefficient. This error could be critical, for example, when one is attempting to qualify a facility for the measurement of pass-by noise. In this paper we propose a remedy - to measure the actual tube attenuation and to use this value, as opposed to the value recommended by the standards, to correct the measured sound absorption. We also recommend an alternative way to determine the microphone phase error.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p184.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p92" class="affilation"></a>Influences of Compression Effect on Sound Absorption Characteristics</h2>
<h3>Chao-Nan Wang, Ya-Jung Lee, Yan-Min Kuo, Shih-Kai Chen</h3>
<p class="affilation">Department of Engineering Science and Ocean Engineering, National Taiwan University, 1, Sec. 4, Roosevelt Road, Taipei, Taiwan, 106, ROC</p>
<p><b>ABSTRACT</b><br>
The object of this research is to investigate the effect of compression on the sound absorption characteristics of a porous material. A porous material subjects to compression effect will induce the changes of density, thickness, porosity, etc. and consequently the sound absorption ability. In this work, a transfer matrix method is applied to investigate the effect of compression on sound absorption properties. The porous materials treated in this study are considered as elastic bodies rather than rigid ones. The absorption coefficients of the uncompressed and compressed porous material are initially calculated and verified from the experimental measurements. Finally the numerical predicted sound absorption coefficients for the compressed porous material are investigated.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p92.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p386" class="affilation"></a>Acoustical Properties of Polyurethane Open Cells Materials: Experimental Investigation and Theoretical Models</h2>
<h3>Francesco Pompoli, Paolo Bonfiglio</h3>
<p class="affilation">Dipartimento di Ingegneria, Università di Ferrara, Ferrara, Via Saragat, 1, Italy</p>
<p><b>ABSTRACT</b><br>
In this work results about the experimental investigation on polyurethane open cell materials are reported. The materials have shown different acoustical performances, due mainly to nonhomogeneity of the tested samples. In this paper the experimental acoustical parameters will be discussed in terms of some physical quantities both measured (airflow resistivity, open porosity and tortuosity) and inversely determined from those acoustical data (viscous and thermal characteristic lengths) by using genetic algorithms. Furthermore correlations between some physical parameters will be shown and discussed. Finally the application of the phenomenological model proposed by Johnson-Champoux and Allard will be presented.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p386.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p160" class="affilation"></a>Standardization of Road Traffic Noise Map in Korea</h2>
<h3>In-Sun Park (1), Sang-Kyu Park (1), Daejoon Kang (2)</h3>
<p class="affilation">(1) Department of Environmental Engineering, Yonsei University Wonju Campus, Wonju, Gangwon, 220-710, Korea (2) National Institute of Environmental Research, Kyungserdong Sergu, Inchun 404-708, South Korea</p>
<p><b>ABSTRACT</b><br>
Since study on noise map in Korea has begun in the late 1990, focus was on how to use interpolation methods of Arc GIS to compare the measured noise data with predicted result. However, use of professional noise map has been very rare because basic data such as information of roads, traffic flows and geography are not enough. In this study, noise maps of a city in Korea have been made using commercial noise map software by measuring the basic data in the city. This result will be used to evaluate the environmental impact of noise from various noise sources and to implement the Korean noise map standard.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p160.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p313" class="affilation"></a>Development of a Semi-Empirical Model of Mechanical Hysteresis for Sandwich Composite Materials, and System Identification Using Heuristic Optimization Methods</h2>
<h3>Klaus H. Hornig, George T. Flowers</h3>
<p class="affilation">Department of Mechanical Engineering, Auburn University, 270 Ross Hall, Auburn University, AL 36849-5341, USA</p>
<p><b>ABSTRACT</b><br>
Generally speaking, of the fundamental dynamic mechanical properties - mass, damping, and stiffness, damping is usually the most difficult to quantify. This is perhaps particularly true for composite materials which tend to have substantially higher damping than comparable isotropic materials and therefore having an accurate representation is correspondingly more important. Accordingly, some heuristic optimization techniques for the identification of the dynamic characteristics of honeycomb-core sandwich composite materials have been suggested, such as Particle Swarm Optimization (PSO) and Genetic Algorithms (GA). Experimental measurements of the dynamic responses (in the form of hysteresis loops) of simply-supported composite beam samples have been carried out, and a simplified semi-empirical mathematical model has been developed for such a system, tailored from individual experimental observations of the dynamic behavior of the samples when they are excited at their mid-points by sinusoidal displacement waves. The hysteresis loops that were obtained are for several frequencies and excitation amplitudes around the first mode of vibration. The analytical model contains four unknown system parameters, which must be identified by both optimization techniques utilized. The performance of these optimization methods are compared with computer-generated and experimental hysteresis loops. In addition, the effect of noise contamination in the signals has been studied in order to assess the search accuracy of the optimization algorithms under such conditions.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p313.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p746" class="affilation"></a>Estimation of Sound Absorption Coefficients of Porous Materials</h2>
<h3>Marianna Mirowska, Kazimierz Czyżewski</h3>
<p class="affilation">ITB - Building Research Institute, Acoustics Department, 02-765 Warsaw, Ksawerow 21, Poland</p>
<p><b>ABSTRACT</b><br>
In the paper, the influence of structural parameters on sound absorption properties of porous materials is analysed. The theoretical and empirical relationships between sound absorption coefficients and air flow resistivity of material and the thickness of the layer are discussed. The characteristics of sound absorption coefficients for several porous materials calculated in accordance with the procedure recommended by EN 12354-6:2003 are compared with measured values obtained in reverberation room and tube method. The nomograms, which allow to estimate sound absorption coefficients from knowledge of air flow resistivity and the thickness of material layers, are presented. From these graphs optimal values of air flow resistivity and the thickness of sound absorption materials can be evaluated.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p746.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p385" class="affilation"></a>Frequency Dependent Tortuosity Measurement by Means of Ultrasonic Tests</h2>
<h3>Paolo Bonfiglio, Francesco Pompoli</h3>
<p class="affilation">Dipartimento di Ingegneria, Università di Ferrara, Ferrara, Via Saragat, 1, Italy</p>
<p><b>ABSTRACT</b><br>
The tortuosity is a fundamental parameter which gets involved in the description of the complexity of the path of the sound wave propagating within a porous material. Several methods have been developed to measure the tortuosity, based on electrical resistivity measurements, high frequency acoustic transmission and reflection measurement and ultrasonic tests. In the present work it has been developed an equipment for determining tortuosity based on the determination of the high frequency limit for the ratio between the sound speed in air and the real part of complex phase velocity within the material. The above mentioned ratio can be evaluated from the phase difference, in the frequency domain, of an ultrasonic pulses between two transducers, with and without material to be tested. The results is a frequency dependent tortuosity curve, that has to be handled in order to get the value of the parameter when frequency tends to infinity. In this work some considerations about these manipulations are reported and discussed. Furthermore, when highly dissipative materials are tested, the signal may be corrupted because of the low S/N ratio. In this paper different receiving transducers are used and different stimuli are applied in order to improve the accuracy of the measurement.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p385.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p191" class="affilation"></a>Performance of Perforated Facing Absorbers</h2>
<h3>Robert Hooker</h3>
<p class="affilation">Division of Mechanical Engineering, The University of Queensland, Brisbane, QLD 4072, Australia</p>
<p><b>ABSTRACT</b><br>
The paper presents extended results from a study of the effect of air-gaps in absorbers with perforated facing. Normal incidence absorption coefficient is measured for a wide range of parameters. There are two facing arrangements, each with open area 14% but with two different hole sizes, 2.5 and 6.35 mm. The cavity behind the facing ranges from 100 to 350 mm in several steps. Absorbent material in the cavity is glasswool in either 50 or 75 mm thickness, placed over the entire range from no gap in front of the absorbent to no gap behind the absorbent. The empty cavity is included. Experimental results are compared with coefficients calculated using a prediction package. The measurements use the travelling microphone technique in the impedance tube method and approaches that allow an extended frequency range are presented.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p191.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p546" class="affilation"></a>Stability of Sound Speed and Attenuation Identified in Material Samples</h2>
<h3>Vincent Martin (1), Vanessa Martin (2,3), Philippe Poullain (3)</h3>
<p class="affilation">(1) Institut Jean Le Rond d’Alembert, CNRS/Paris VI, 2 Place de la gare de Ceinture, 78210 St Cyr l’Ecole, France (2) Laboratoire National Hydraulique et Environnement, EDF, 6 quai Watier, 78400 Chatou, France (3) Laboratoire GeM, Institut de Recherche en Génie Civil et Mécanique, CNRS/Université de Nantes/Ecole Centrale de Nantes, IUT de St Nazaire, 58 rue Michel Ange, 44600 St Nazaire, France</p>
<p><b>ABSTRACT</b><br>
Within an experimental framework, in porous saturated media, it remains a delicate problem to identify sound speed and attenuation, two related characteristics. Using a temporal method is problematic as samples are short and, moreover, the Fourier transform is unable to extract information from the frequency domain. Wavenumbers can be identified by stationary methods, but the ratio of displacements at the sample exit to displacements at the entry does not depend linearly on the wavenumber. A non-convex minimization is quite unreliable, since it depends on the initial value it has to start from. A genetic algorithm could certainly be of some help here. However, with a rather more physical insight, when dealing with samples of different lengths, averaging the results could already improve reliability. Here we suggest going further in the same vein, using a different approach to reach a robust result. Indeed, as said previously, the function available is not linear with regard to the parameters. But starting from a first identified value, the perturbation method makes it possible to linearize the function with regard not to the parameter itself but to its variation. Such an approach provides not only information about the stability of the function with the parameter variation but also, within the limits of stability, an analytical solution, thanks to the now convex optimization of the variation which will refine the initial value. This presentation provides an analysis of the approach. It is the first step towards the study of how the model influences the stability of the identification, a problem which is definitely of interest today.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p546.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p142" class="affilation"></a>Active Noise Control on High Frequency Narrow Band Dental Drill Noise: Preliminary Results</h2>
<h3>Erkan Kaymak (1), Mark Atherton (1), Ken Rotter (2), Brian Millar (3)</h3>
<p class="affilation">(1) School of Engineering and Design, Brunel University, Kinston Lane, Uxbridge, UB8 3PH, UK (2) Department of Engineering Systems, London South Bank University, Borough Road, London, SE1 0AA, UK (3) Primary Dental Care, King’s College London Dental Institute at Guy’s, King’s and St Thomas’ Hospitals, Caldecot Road, London, SE5 9RW, UK</p>
<p><b>ABSTRACT</b><br>
Dental drills produce a characteristic noise that is uncomfortable for patients and is also known to be harmful to dentists under prolonged exposure. It is therefore desirable to protect the patient and dentist whilst allowing two-way communication. A solution is to use a combination of the three main noise cancellation methods, namely, Passive Noise Control, Adaptive Filtering and Active Noise Control. Dental drill noise occurs at very high frequency ranges in relation to conventional ANC, typically 2 kHz to 6 kHz and it has a narrow band characteristic due to the direct relation of the noise to the rotational speed of the bearing. This paper presents a design of an experimental rig where first applications of ANC on dental drill noise are executed using the standard filtered reference Least Mean Square (FXLMS) algorithm. The secondary path is kept as simple as possible, due to the high frequency range of interest, and hence is chosen as the space between headphone loudspeaker and error microphone placed in the ear (input of the headphone loudspeaker and the output of the error microphone). A standard headphone loudspeaker is used for the control source and the microphone inside of an “Ear and Cheek Simulator Type 43AG” is used as the error microphone. The secondary path transfer function is obtained and preliminary results of the application of ANC are discussed.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p142.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p447" class="affilation"></a>Nonlinear Secondary Path Model Identification</h2>
<h3>Jarosław Figwer</h3>
<p class="affilation">Institute of Automatic Control, Silesian University of Technology, Gliwice, Poland</p>
<p><b>ABSTRACT</b><br>
In the paper a new approach to nonlinear secondary path model identification for feedforward active noise control systems is presented. In the proposed approach the nonlinear secondary path is modeled as Wiener system. The model of Wiener system is identified using multisine random excitation. This excitation used in a specially designed identification experiment allows to decompose Wiener model identification problem into linear dynamic part and static nonlinearity identification problems. Properties of the presented nonlinear secondary path identification method in the case of off- and on-line model identification are discussed.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p447.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p401" class="affilation"></a>Active Control of Vibration and Radiated Sound of a Submerged Circular Plate</h2>
<h3>Jerzy Wiciak</h3>
<p class="affilation">University of Science and Technology - AGH, Department of Mechanics and Vibroacoustics, Al. Mickiewicza 30, 30-095 Kraków, Poland</p>
<p><b>ABSTRACT</b><br>
Complex analysis of characteristic of underwater noise allows to find several features typical for underwater noise produced by ships as well as correlations between mechanical activity of ship’s mechanism and generated underwater sound. Their vibration activity might be reduced by applying active treatments utilising piezoelectric sensors and actuators. The paper explores the potentials of active control of vibrations and sound through the application of a thin round plate clamped on the edges in a rectangular enclosure. The plate is loaded on one side by heavy fluid (water) and on the other side has contact with an air. On the side of the gaseous medium, eight piezoelectric elements are bonded to the plate with a thin layer of glue. Measurements of the acoustic pressure were taken over the whole length of the aquarium, for the fixed position of a hydrophone in the vertical and for variable height yet in a fixed distance from the radiation source. The finite element method analysis was performed, with the application of ANSYS computer package. The numerical solutions were confirmed experimentally.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p401.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p701" class="affilation"></a>A Brief Review of Active Control of Environmental Noise and its Applications</h2>
<h3>Jingnan Guo (1), Jie Pan (2), Murray Hodgson (3)</h3>
<p class="affilation">(1) Noise section, Department of Environment and Conservation, Government of Western Australia, 168 St. Georges Terrace, Perth, WA 6000, Australia (2) School of Mechanical Engineering, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia (3) Department of Mechanical Engineering, University of British Columbia, 3rd Floor, 2206 East Mall, Vancouver, B.C., V6T 1Z3, Canada</p>
<p><b>ABSTRACT</b><br>
Although active noise control has been intensively explored for several decades, its practical and successful applications are still limited to a few specific areas. Active control of environmental noise has also received extensive attention for many years. Examples include active noise control in open spaces, active noise control in enclosed environments, and active noise control barriers. However, the application of active control to real environmental noise problems has not yet enjoyed much significant progress, even though environmental noise, especially low-frequency environmental noise, is becoming an important issue that raises increasing concerns from communities. This paper reviews the progress made so far from studies of active control of environmental noise, and discusses issues affecting their practical application. Future directions of active environmental noise control research and its applications are also discussed.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p701.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p458" class="affilation"></a>Suboptimal Multichannel Adaptive ANC System</h2>
<h3>Krzysztof Czyż, Jarosław Figwer</h3>
<p class="affilation">Institute Automatic Control, Silesian University of Technology, Akademicka 16, 44-100 Gliwice, Poland</p>
<p><b>ABSTRACT</b><br>
The paper presents a new approach to real-world implementation of multichannel adaptive active noise control (ANC) systems. In the proposed approach the multichannel adaptive ANC system is decomposed into a constellation of single channel autonomous adaptive active noise controllers. They exchange models of electro-acoustic cross-interaction paths by broadcasting them over the local Ethernet network. These models are used to estimate signals used by each of single channel autonomous adaptive controllers in the constellation to compensate their mutual cross-interactions. The presented idea enables to implement the multichannel adaptive ANC system as the constellation of single channel autonomous adaptive active noise controllers that can be easily tuned to specific application needs.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p458.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p209" class="affilation"></a>Feedback Supervising Feedforward Minimum-Variance Control of Acoustic Noise</h2>
<h3>Marek Pawelczyk</h3>
<p class="affilation">Institute of Automatic Control, Silesian University of Technology, ul. Akademicka 16, 44-101 Gliwice, Poland</p>
<p><b>ABSTRACT</b><br>
Minimum-Variance Control is one of the dominating strategies for actively suppressing acoustic noise. Feedforward structure is generally preferred if a reference signal is available. Otherwise, feedback structure is the interim solution. The purpose of this paper is to design an optimal combined control-weighted minimum variance noise control system. In the proposed approach feedforward is the primary control strategy. Feedback control is added to the already operating feedforward. It aims at controlling the residual noise of feedforward control. However, the main purpose of closing the external loop is to benefit from properties of feedback control. Appropriate controllers can be designed in the time domain, frequency domain or transform domain. The latter approach, based on polynomial operations, including Diophantine equations has been chosen. Correctly applied control weighting for both techniques guarantees stable operation for a non-minimum phase plant. Performance of the combined system is compared to performance of the individually operating feedforward system. Different time dependences are considered. Theoretical analysis is supported by simulation experiments based on data obtained from a real-world active headrest system.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p209.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p391" class="affilation"></a>Robust Control Design for Active Noise Control Systems of Ducts with a Ventilation System Using a Pair of Loudspeakers</h2>
<h3>Yasuhide Kobayashi (1), Hisaya Fujioka (2)</h3>
<p class="affilation">(1) Faculty of Engineering, Nagaoka University of Technology, Nagaoka, 940-2188, Japan (2) Graduate School of Informatics, Kyoto University, Kyoto, 606-8501, Japan</p>
<p><b>ABSTRACT</b><br>
In this paper we deal with design problems of active noise control systems with a pair of loudspeakers, in order to improve the system performance achieved by a single loudspeaker presented in our previous study where advantages of robust control (sampled-data H<sub>∞</sub> control) design have been shown by comparing to the existing adaptive control based design. Firstly, as a pair of loudspeakers, the Swinbanks’ source is composed of an appropriate delay and two loudspeakers whose dynamic characteristics are equivalent, then similar advantages of robust control design are shown by experimental results with the ventilation system. Secondly, the pair of loudspeakers is considered as two independent actuators to meet dynamic characteristic difference of the loudspeakers, then less-conservative SIMO controller is designed by robust control design to improve system performance.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p391.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p659" class="affilation"></a>Noise Suppression Using Active Noise Control and Masking</h2>
<h3>Amit Rajora (1), Woon-Seng Gan (1), Sen M Kuo (2), Yong-Kim Chong (1)</h3>
<p class="affilation">(1) School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore (2) Department of Electrical Engineering, Northern Illinois University, USA</p>
<p><b>ABSTRACT</b><br>
This paper attempts to make the public/workplace environment more pleasant by combining techniques of active noise control (ANC) and the limited ability of the human auditory system to register a sound in the vicinity of another sound of sufficiently higher intensity. The paper examines the limitations of ANC and masking techniques, and proposes a way to integrate these techniques. A process for the selection of a suitable masker and its subsequent integration with an ANC system will be introduced. A solution has been proposed to overcome the difficulties of achieving a reduction of the undesirable, as well as preserving/enhancing the desirable content in the audio domain. Several implementation issues will also be addressed in this paper towards lowering the annoyance level of engine noise.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p659.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p220" class="affilation"></a>The Improved Active Control Algorithm for Marine Diesel Two-Stage Vibration Isolation System</h2>
<h3>Bin Xiao, Zhi-gang Liu, Wan-you Li, Xue-guang Liu , Tie-jun Yang</h3>
<p class="affilation">School of Power and Energy Engineering, Harbin Engineering University, Harbin, 150001, P. R. China</p>
<p><b>ABSTRACT</b><br>
The active control technology was carried out on the marine diesel two-stage vibration isolation system (MDTVIS), the active control technology was able to make up for passive vibration isolation technology in low frequency range. The construction of the secondary path was one of the most important sectors, which had a full impact on active vibration isolation performance. Nonlinear components were comprised in the secondary path, which were principally the nonlinear vibration of multi-degrees of freedom in the practical MDTVIS system and nonlinear control path in the hydraulic servo actuator. The nonlinearity was not ignorable in coping with the second path, so that, the vibration isolation performance was greatly influenced by the secondary path in the active control technology with the classic adaptive comb-type filter. By combination the model reference adaptive inverse control strategy with the nonlinear robust control technology, the linearity control algorithm was designed, and then the classic adaptive comb-type filter algorithm was carried out for new system, herein the hybrid control strategy was constructed to applying to the secondary path in the practical MDTVIS system. The proposed hybrid control strategy was able to improve the initial active vibration isolation control algorithm with adaptive comb-type filter, and overcome shortcomings of the vibration strengthened in some multi-harmonic-frequency sites in low frequency range. The total performance of vibration isolation coupling with multi-path was improved in balance.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p220.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p339" class="affilation"></a>Robust Pole Placement for Active Vibration Control of Seismic-Excited Buildings</h2>
<h3>Haiping Du, Nong Zhang</h3>
<p class="affilation">Mechatronics and Intelligent Systems, Faculty of Engineering, University of Technology, Sydney, PO Box 123, Broadway, NSW 2052, Australia</p>
<p><b>ABSTRACT</b><br>
In this paper, the robust controller design problem for active vibration control of seismic-excited building structures by means of pole placement method is studied. In particular, the building structures are assumed to have parameter uncertainties, and the design of controller will assure the pole locations of the closed-loop system are inside an indicated subregion on the left-hand side of complex plane in spite of the parameter uncertainties. For the building models, the parameter uncertainties dealt with belong to the polytope type uncertainties and are assumed to be the variations of the structural masses, stiffnesses, and damping coefficients. The quadratic stability test using the fixed quadratic Lyapunov function is studied and the sufficient conditions for the existence of a robust stabilising state feedback controller are presented as linear matrix inequalities (LMIs). The performance of the presented approach is demonstrated by numerical simulations on the vibration control of building structure subject to seismic excitation. It is confirmed that the designed controller can effectively attenuate the structural vibration when the parameter uncertainties exist.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p339.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p16" class="affilation"></a>Active Control for Vibroprotection of Operators of Technological Machines</h2>
<h3>L. A. Rybak, A. V. Chichvarin, Y.A. Shatokhin</h3>
<p class="affilation">Starooskolsky State Institute of Moscow State Institute of Steel and Alloys (Department of Automation) 309516 Belgorodskaya regio, Stary Oskol, m-n Makarenko, 42, Russia</p>
<p><b>ABSTRACT</b><br>
The electrohydraulic mechanism of a vibroprotection system with a digital regulator is considered. A mathematical model of the system is constructed. An optimal operational algorithm for the regulator is synthesized on the basis of the Riccati equation. This permits simulation of the system with various external perturbations and under the action of actual vibrational noise at the workstation of an SBSh-250 drilling machine.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p16.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p788" class="affilation"></a>Simultaneous Optimization of Structure Control of Smart Tensegrity Structures</h2>
<h3>M. Ganesh Raja, S. Narayanan</h3>
<p class="affilation">Machine Design Section, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai-600 036, India</p>
<p><b>ABSTRACT</b><br>
A multidisciplinary design optimization (MDO) of a smart tensegrity structure using genetic algorithm is considered as a mixed discrete - continuous objective programming problem. Robust H<sub>2</sub> and H<sub>∞</sub> controller norms are considered as the objective. Performance of the H<sub>2</sub> and H<sub>∞</sub> controllers for vibration control of the tensegrity structures are compared. A nested optimization strategy is used. The optimal gain matrices of the controller and estimator are found by solution of the corresponding Ricatti equations in the inner iteration as the first step. The optimal structural parameters are found in the outer iteration as the next step. Design variables include twist angle and the locations of the actuator, which are either discrete or continuous. The force generated by the electro-mechanical coupling of the piezoelectric actuator is used in the formulation. The tensegrity structure of class-1 comprising of two modules with piezoelectric actuators is optimized.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p788.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p490" class="affilation"></a>A Feedforward Active Noise Control System for Ducts Using a Passive Silencer to Reduce Acoustic Feedback</h2>
<h3>M. Larsson, S. Johansson, L. Håkansson, I. Claesson</h3>
<p class="affilation">Department of Signal Processing, Blekinge Institute of Technology, SE-372 25 Ronneby, Sweden</p>
<p><b>ABSTRACT</b><br>
Ventilation systems installed in buildings usually generate low-frequency noise because the passive silencers commonly used to attenuate the ventilation noise are not effective in the low-frequency range. A method proven to effectively reduce low-frequency noise in a wide variety of applications is active noise control (ANC). A feedforward ANC system applied to duct noise normally uses a reference microphone, a control unit, a loudspeaker to generate the secondary noise created by the controller, and an error microphone. The secondary noise generated by the loudspeaker will travel both downstream canceling the primary noise, and upstream to the reference microphone, i.e. acoustic feedback. The acoustic feedback may result in performance reduction and stability problems of the control system. Common approaches to solve the feedback problem result in more complex controller structures and/or system configurations than the simple feedforward controller, e.g. introducing a feedback cancellation filter in the controller in parallel with the acoustic feedback path, or using a dual-microphone reference sensing system. This paper presents a simple approach to reduce the acoustic feedback by using a basic feedforward controller in combination with a passive silencer. Simulations show that efficient acoustic feedback cancellation is achieved by using a passive silencer. In the experimental setup another advantage with using a passive silencer is that the frequency response function of the forward path, which is to be estimated, is smoother, i.e. most of the dominant frequency peaks in the frequency response function when not using a passive silencer is reduced. This in turn results in an acoustic path that is less complex to estimate with high accuracy using an adaptive FIR filter steered with the LMS algorithm.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p490.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p366" class="affilation"></a>Active Vibration Control of Hard-Disk Drives Using PZT Actuated Suspension Systems</h2>
<h3>Meng-Shiun Tsai, Wei-Hsiung Yuan, Jia-Ming Chang</h3>
<p class="affilation">Department of Mechanical Engineering, National Chung-Cheng University, 168, University Rd., Ming-Hsiung Chia-Yi, Taiwan</p>
<p><b>ABSTRACT</b><br>
In this paper, an active PZT-based suspension system is designed to block vibration from the ground disturbance into hard-disks when notebooks experience incident drop or impact. To build an active bridge for isolating vibration, the suspension structure of the hard-disk’s case is redesigned such that the piezoelectric actuators can be attached and perform active controls. Due to the complicated structures of the notebook, experiments are performed to obtain the frequency response of the plant. Two resonances are found within the control bandwidth of 0 to 100 Hz. A quantitative Feedback Theory (QFT) controller is designed based on the frequency response function. It is shown that more than 20 dB reductions are achieved at the first and second modes. The settling time of the impact testing can be reduced by more than 90 percents. Moreover, the maximum peak of the impact testing is only about 50% of the uncontrolled case.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p366.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p460" class="affilation"></a>Position Dependent Linearized Elastic Models of Parallel Robot Systems with Embedded Smart Devices for Vibration Suppression Control Algorithms</h2>
<h3>Michael Rose (1), Stephan Algermissen (1), Ralf Keimer (1), Christoph Budde (2)</h3>
<p class="affilation">(1) Institute of Composite Structures and Adaptive Systems, German Aerospace Center (DLR), Germany (2) Institute of Machine Tools and Production Technology, Technical University Braunschweig, Germany</p>
<p><b>ABSTRACT</b><br>
The achievable accelerations of serial robot systems are limited by the weight of the axis drives, which are moved while traversing the given trajectory of the manipulator. By switching to parallel robot systems, it is possible to mount all drives on the rigid base platform. This reduction in weight of the movable linkage increases the possible accelerations, while retaining suitable position accuracy. Much weight can be reduced further on by using composite fibre materials for cranks and rods of each parallel linkage. Such systems are light and stiff and enable low cycle times, but unfortunately they are usually poorly damped as elastic structures and therefore tend to perform unwanted elastic vibrations during motion. In this paper, position dependent models are investigated, which are suitable to generate linearized elastic system models at arbitrary positions in the work space of the robot structure. These models are further modified to include active piezo electric patch devices as actuators and sensors, which can be used to control and observe the elastic structural deformations. The final electro-mechanical coupled system model can be used to develop and simulate state space vibration control algorithms.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p460.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p805" class="affilation"></a>Experimental Modal Analysis of an Actively Controlled Scaled Metro Vehicle Car Body</h2>
<h3>S. Popprath (1), A. Schirrer (2), C. Benatzky (2), M. Kozek (2), J. Wassermann (1)</h3>
<p class="affilation">(1) Institute of Mechanics and Mechatronics, Division of Measurement and Actuator, Technology,Wiedner Hauptstraße 8-10/E325/A4, A-1040 Vienna, Austria (2) Institute of Mechanics and Mechatronics, Division of Control and Process Automation, Gußhausstraße 27-29/E325/A5, A-1040 Vienna, Austria</p>
<p><b>ABSTRACT</b><br>
This paper deals with the experimental modal analysis of an actively controlled scaled laboratory-model of a flexible metro vehicle car body. To investigate such a control system a 1/10--scaled laboratory model of a metro vehicle car body has been built. Control forces are applied-to the structure by two piezoelectric stack actuators mounted in specially designed consoles,-which are bonded to the side members of the structure. The car body itself is suspended in a-test bed frame by four coil springs to obtain a free-free suspension configuration. An electrodynamic-shaker is used to generate broad band excitation forces, which in real operation enter-the structure at the application points of the secondary suspension system. The state feedback-controller and the observer are designed by an LQR-based modal weighting procedure implemented-in Matlab/SIMULINK. To investigate the reduction of the amplitudes of the shaker-induced vibrations a non-contact measurement utilizing a laser scanning vibrometer is applied.-In order to verify the achieved performance, open and closed loop disturbance-displacement-transfer functions and the mode shape corresponding to specific natural modes are identified by-an experimental modal analysis. Since the ride quality is mainly influenced by the lowest global-vibration modes, the investigation is focused on the first torsional mode and a low vertical bending-mode of the car body.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p805.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p792" class="affilation"></a>Simulation of a Combined Switched and Inductive Shunt Control Acting on a 2D Structure</h2>
<h3>Salvatore Ameduri (1), Monica Ciminello (2), Antonio Concilio (1)</h3>
<p class="affilation">(1) Laboratory of Smart Structures, The Italian Aerospace Research Centre C.I.R.A. scpa, Capua, Via Maiorise, Italy (2) Department of Aeronautical Engineering, “Federico II” University, Naples, Via Claudio, Italy</p>
<p><b>ABSTRACT</b><br>
Several control techniques have been developed to improve the reduction of sensitivity of structural elements dynamic response to both parameter variations and disturbances attenuations within the control system bandwidth. The research activity has shown how passive and active control strategies may be complementary for facing many of the structural dynamic problems. As a matter of fact, while the passive ones demonstrate efficiency for the highest frequencies band, the active systems demonstrate efficiency in a wider broad band domain, despite of the large required power supply and the high cost hardware. Semi-active controls assure advantages of both passive and active control techniques. In detail, the absence of an external power supply, the reduced vulnerability to power failure, the self-powered architecture, make the semi-active controls simple to be managed and cheaper. The possibility of jointly implementing both a switched and an inductive shunt architecture may guarantee a more efficient multi mode control. As a matter of fact, it is possible to simultaneously control a low and a high frequency mode through a switch and an inductive architecture. To achieve this result, the RLC parameters of the switch circuit (synchronised on the lower mode) have to be chosen so that its normal frequency is coincident with the higher structural mode to be controlled.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p792.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p683" class="affilation"></a>Dynamic Modelling and Input Shaping Control for Positioning Stage</h2>
<h3>Sang-Won Park (1), Jun-Won Jang (1), Hun-Suk Choi (1), Seong-Wook Hong (2), William Singhose (3)</h3>
<p class="affilation">(1) Department of Mechatronics, Kumoh National Institute of Technology, 1 Yangho-dong, Gumi, Gyeongbuk 730-710, Korea (2) School of Mechanical Engineering, Kumoh National Institute of Technology, 1 Yangho-dong, Gumi, Gyeongbuk 730-710, Korea (3) School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, USA</p>
<p><b>ABSTRACT</b><br>
This paper presents the dynamic analysis and input shaping control of a positioning stage. Vibration characteristics of positioning stages are affected not only by the structural dynamics but by the servo actuators that consist of the mechanism, driving motor and controller. This paper proposes an integrated dynamic model to accommodate both the structural dynamics and the servo actuators. Theoretical modal analysis with a commercial finite element code is carried out to investigate the dynamic characteristics of the experimental positioning stage. Experiments are performed to validate the theoretical modal analysis and estimate the equivalent stiffness due to the servo actuators. This paper deals with an input shaping scheme to suppress vibration of the positioning stage. Input shapers are systematically implemented for the positioning stage in consideration of its dynamics. The effects of servo control gain are also investigated. The experiments show that input shaping effectively removes residual vibrations and then improves the performance of positioning stage.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p683.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p255" class="affilation"></a>Initial Experiments with a Finite Element Model of an Active Boring Bar</h2>
<h3>Tatiana Smirnova (1), Henrik Åkesson (1), Lars Håkansson (1), Ingvar Claesson (1), Thomas Lagö (2)</h3>
<p class="affilation">(1) Department of Signal Processing, Blekinge Institute of Technology, PO Box 520, SE-372-25 Ronneby, Sweden (2) Acticut International AB, Gjuterivägen 7, SE-311-32 Falkenberg, Sweden</p>
<p><b>ABSTRACT</b><br>
One of the most troublesome sources of vibration in metal cutting is the vibration caused by internal turning operations. A boring bar is a tool holder which is used to machine deep precise cavities inside a workpiece material. In order to perform this internal turning the boring bar usually has a large length-to-diameter ratio, and thus the boring bar vibrations are easily excited by the material deformation process during metal cutting. The vibrations are related to the lower order fundamental bending modes of the boring bar. To overcome the vibration problem an active control technique can be used. In particular, by utilizing an active boring bar with an embedded piezoceramic actuator and a suitable controller, the primary boring bar vibrations originating from the material deformation process may be suppressed with secondary “anti-” vibrations. In order to produce an active boring bar several decisions should be done, i.e. the characteristics of the actuator, the position of the actuator in the boring bar, etc. This usually implies that several prototypes of an active boring bar should be produced and tested, thus the design of an active boring bar is a tedious and costly procedure. Therefore a mathematical model which would incorporate the piezo-electric effect in order to predict the dynamic properties and the response of the active boring bar are of great importance. This paper addresses the development of a “3-D” finite element model of the system “boring bar-actuator-clamping house”. The spatial dynamic properties of the active boring bar, i.e. its natural frequencies and mode shapes, as well as the transfer function between the voltage applied to the actuator and acceleration of boring bar are calculated based on the “3-D” FE model and compared to experimentally obtained estimates.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p255.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p199" class="affilation"></a>Experimental Identification of Fractional-Derivative Parameters of a Damping Material Using the Optimization Technique</h2>
<h3>Sun-Yong Kim, Doo-Ho Lee</h3>
<p class="affilation">Department of Mechanical Engineering, Dongeui University, Busan, 614-714, Republic of Korea</p>
<p><b>ABSTRACT</b><br>
In this paper, an efficient identification method of the material parameters is proposed using an optimization technique and applied to real materials to identify the fractional-derivative-model parameters of the material. In the proposed method, frequency response functions are measured from a cantilever beam impact test. The frequency response functions on the same points with the measured one are calculated by using an FE model with the equivalent stiffness approach. The differences between the measured and the calculated FRFs are minimized using a gradient-based optimization algorithm in order to identify the real values of the parameters. Four FRF’s of a damped beam structure are measured in an environmental chamber at different temperatures and used as reference responses. An impact hammer and a laser vibrometer are used to measure the reference responses. Both linear and nonlinear relationships between the logarithmically-scaled shift factors and temperatures are examined in identifying the material parameters. The experimental results show that the proposed method accurately identifies the fractional-derivative-model parameters even for real damping materials.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p199.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p363" class="affilation"></a>State Estimation Method for Sound Environment System with Unknown Structure and its Application to Evaluation of Road Traffic Noise</h2>
<h3>Akira Ikuta (1), Mitsuo Ohta (2), Hisako Masuike (1)</h3>
<p class="affilation">(1) Prefectural University of Hiroshima, Hiroshima, 734-8558, Japan (2) Emeritus, Hiroshima University, Hiroshima, 732-0824, Japan</p>
<p><b>ABSTRACT</b><br>
The actual sound environment system exhibits various types of linear and non-linear characteristics, and it often contains an unknown structure. Furthermore, the observations in the sound environment are often in the level-quantized form. In this paper, a method for estimating the specific signal for stochastic systems with unknown structure and the quantized observation is proposed by introducing a system model of the conditional probability type. The effectiveness of the proposed theoretical method is confirmed by applying it to the actual problem of psychological evaluation for road traffic noise.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p363.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p595" class="affilation"></a>High Quality Recording Through Microphone Array in Noisy and Reverberant Environment</h2>
<h3>Hideo Tsuru (1), Hirofumi Nakajima (2), Yusaku Fujita (1)</h3>
<p class="affilation">(1) Nittobo Acoustic Engineering, 1-21-10 Midori, Sumidaku, Tokyo, 130-0021, Japan (2) Honda Research Institute Japan, 8-1 Honmachi,Wako, Saitama, 351-0188, Japan</p>
<p><b>ABSTRACT</b><br>
Noise and reverberation often disturb high quality sound recording in real environments. Especially when a microphone is set to be far from a sound source these effects become prominent. In order to circumvent these difficluties, the recording techniques by array microphones followed by sevral sophisticated signal processings were proposed. However, a degradation of sound quality often occurs by signal processing because of an exceeding modification. Moreover an adaptive or blind method does not well utilize measurable acoustic information so fails to obtain the sound reconstructed with high fidelity. Here impulse response data which were measured in real environments and the theoretical investigations carried out to obtain the filter coefficients which are robust to environmental changes. The high quality sound is reproduced by these signal processings.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p595.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p9" class="affilation"></a>In-Car Speech Enhancement Using Ensemble Empirical Mode Decomposition</h2>
<h3>Jiafang Zhang, Hai Huang, Xiangxian Chen</h3>
<p class="affilation">Department of Instrument Engineering, Zhejiang University, Hangzhou 310027, P.R.China</p>
<p><b>ABSTRACT</b><br>
The performance of the human-machine dialogue at in-car environment is considerably deteriorated by background noises and other disturbances. In this paper, the authors present an in-car speech enhancement (ICSE) method to improve quality of speech signals suffering the in-car noises. The method is based on a novel signal processing technology called the ensemble empirical mode decomposition (EEMD). By using EEMD, the noisy speech signals are decomposed as a set of intrinsic mode functions (IMF). Then, the nonlinear least-square estimation and signal-to-noise ratio (SNR) are employed to find out the optimal weighting coefficients of those IMFs dominating the speech signals. Finally, the enhanced speech signals, where in-car noises are suppressed, are obtained by the reconstruction technique based on the weighting IMFs. Results of the work show that, EEMD is an effective technology of separating pure speech from in-car noises, and the weighting coefficients proposed in this study are also effective for noises reduction as considering the similarity of the signal waveform.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p9.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p230" class="affilation"></a>Determination of Mechanical Properties of a Nonuniform Beam Using the Measurement of the Excited Longitudinal Elastic Vibrations</h2>
<h3>Pavel Anokhin, Vladimir Gordon</h3>
<p class="affilation">Department of the mathematics, Orel State Technical University, Naugorskoe sh., 29, 302020 Orel, Russia</p>
<p><b>ABSTRACT</b><br>
The purpose of this paper is to present the statement of the inverse problem for longitudinal elastic vibrations of a non-uniform beam and the approximate analytical and numeric solutions of this problem under the condition of weak heterogeneity. To solve the inverse problem, certain longitudinal vibrations are excited in the beam and mechanical properties of the non-uniform beam (Young’s module and density) have to be determined from the measured vibration in a certain point of the beam. Under the condition of weak heterogeneity the problem doesn’t lose its importance. Weak heterogeneity can be found in many natural and produced materials. In this case it’s possible to linearize the problem, expressing the difference between the properties of the base homogeneous beam and the properties of the weak heterogeneous beam through the difference between their vibrations and solve the problem. The problem is decomposed into 2 sub-problems - finding the difference between vibrations of the uniform and non-uniform beams (solving the partial differential equation of the 2<sup>nd</sup> order with constant coefficients) and finding the difference between the mechanical properties of the beams (solving the system of linear ordinary differential equations of the 1<sup>st</sup> order).</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p230.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p205" class="affilation"></a>A Proposal to Hi-Tech Pollution Based on the Criterion of “Relationism-First” - A Principle Experiment for the Relation between Acoustic and EM Fields Around VDT</h2>
<h3>Yoshifumi Fujita (1), Mitsuo Ohta (2)</h3>
<p class="affilation">(1) Department of Economics, Management and Information Science, Onomichi University, 1600 Hisayamada-Chou, Onomichi, 722-8506 Japan (2) Emeritus Prof. of Hiroshima University, 1-7-10 Matoba-Chou, Minami-Ku, Hiroshima, 732-0824 Japan</p>
<p><b>ABSTRACT</b><br>
It seems that Hi-tech pollution and many other difficult modern problems come up from even slighting many kinds of complicated relationship among various environmental factors including even ethical or cultural faces and giving priority to only utility over any other everything. In this paper, to solve these problems, we first pay attention to the criterion of “Relationism-First” that once after employing at the first stage of study as many environmental factors as possible at the same time and investigating the mutual correlation among them (for trueness), then our specified interesting cases for engineering application should be considered (for effectiveness). In previous paper, as a trial method for mutual intersubjective analysis, by taking care of light and a shade, that is, two factors of utility and risk, an extended correlation analysis for only two environmental factors has been applied. In this paper, another extended correlation analysis applicable to the fluctuation limited within the finite interval is newly introduced. Furthermore, as a principle experiment for the proposed method, by applying it to the contrasted two environmental factors: magnetic field (related to risk) and sound (related to utility) in EM environment around VDT before and after attachment of Tecno AO (active bio-controller as some magnetic oscillator), the proposed method is experimentally confirmed, too.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p205.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p766" class="affilation"></a>Shock Spectrum Calculation of Structural Response to UNDEX</h2>
<h3>Yu Wang (1), Jianglin Fan (2), Zhiyi Zhang (2), Rongying Shen (2), Hongxing Hua (2)</h3>
<p class="affilation">(1) Naval Research Center, 100073 Beijing, China (2) State Key Laboratory of Mechanical system and Vibration, Shanghai Jiao Tong University, 200030 Shanghai, China</p>
<p><b>ABSTRACT</b><br>
The measured responses of a structure subjected to underwater explosion may deviate from the exact results due to high intensity impact on transducers and signal amplifiers, which will further cause fault SRS (shock response spectrum) analysis if this kind of disturbance is not filtered. In view of the disturbance characteristics, SVD (singular value decomposition) and ARMA filtering techniques are combined to recover the exact response signals from which SRS is computed. The results show that SVD in combination with ARMA filtering is able to separate step-like disturbances from the measured response signals and as a result improves the accuracy of SRS at low frequencies.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p766.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p666" class="affilation"></a>A Numerical Study of Fluid Flow Past a Circular Cylinder at Re = 3900 and a Practical Approach to Noise Prediction</h2>
<h3>A. Pradera (1), G. Keith (2), F. Jacobsen (3), N. Gil-Negrete (1), A. Rivas (4)</h3>
<p class="affilation">(1) CEIT and Tecnun (University of Navarra) - Manuel de Lardizábal 15, 20018, San Sebastián, Spain (2) Odegaard & Danneskiold-Samsoe A/S - Titangade 15, 2200 Copenhagen N, Denmark (3) Acoustic Technology, DTU - Building 352, 2800 Lyngby, Denmark (4) Tecnun (University of Navarra) - Manuel de Lardizábal 13, 20018, San Sebastián, Spain</p>
<p><b>ABSTRACT</b><br>
The aim of this study is the prediction of the aerodynamic noise generated by the fluid flow past a circular cylinder at Re = 3900, combining numerical simulation of the fluid flow with an analytical noise evaluation. This case has been extended to the flow around a cylinder with Re = 140000. The Large Eddy Simulation (LES) turbulence model of FLUENT v6.3 is used in a numerical simulation of the fluid flow. The computations are carried out with double precision and second-order implicit unsteady formulation. First and second order statistics, as well as drag, lift and pressure coefficients obtained in the Computational Fluid Dynamics (CFD) calculations are in good agreement with numerical and experimental data from literature. Once the CFD simulation is validated, an approach to make noise predictions on the basis of CFD simulations is demonstrated. This approach involves deriving analytical expressions describing the relationship between certain statistical flow quantities and the far field acoustic power and is intended to circumvent the potential introduction of large errors that can arise when working directly with pressure and velocity time series. The method is here demonstrated in a very simple example and the obtained Sound Pressure Level (SPL) is compared with numerical and experimental results from the ESPRIT project ALESSIA and also with the SPL derived from the Phillips correlation.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p666.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p759" class="affilation"></a>Demonstration of Inadequacy of Ffowcs Williams and Hawkings Equation of Aeroacoustics by Thought Experiments</h2>
<h3>Alex Zinoviev</h3>
<p class="affilation">Defence Science and Technology Organisation, Maritime Operations Division, Edinburgh, SA, 5111, Australia</p>
<p><b>ABSTRACT</b><br>
In 1952, Sir James Lighthill published a theory of sound radiation by a turbulent fluid flow. This theory was extended by Curle in 1955 to a flow with immoveable rigid boundaries. In 1969, Ffowcs Williams and Hawkings extended this theory to a flow with moving rigid objects and derived an equation, which has since become one of the major tools of prediction of the flow induced noise. In 2004, Zinoviev and Bies re-examined Curle’s derivation and showed a theoretical inconsistency in his calculations. In this paper, the inadequacy of Ffowcs Williams and Hawkings equation for solving problems of sound radiation by a turbulent flow near solid boundaries is demonstrated by its application to simple thought experiments. First, sound radiation by an oscillating solid sphere is compared with sound radiation by a stationary solid sphere in a variable velocity field (vortex street). It is shown that, contrary to the well-known equivalence of these situations, the Ffowcs Williams and Hawkings equation produces different results in these cases. Second, it is demonstrated that this equation predicts significant acoustic radiation by a light solid object carried by a turbulent flow. Finally, sound radiation by an acoustically small rigid plate vibrating parallel to itself is considered. It is shown that Ffowcs Williams and Hawkings equation predicts significant but physically unjustified dipole acoustic radiation with the dipole axis parallel to the plate.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p759.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p558" class="affilation"></a>A 3D Numerical Method to Study Poroelastic Liners with Mean Flow</h2>
<h3>Benoit Nennig, Mabrouk Ben Tahar, Emmanuel Perrey-Debain</h3>
<p class="affilation">Laboratoire Roberval FRE 2833, Département acoustique, Université de Technologie de Compiègne, BP 20529, 60205 Compiègne cedex, France</p>
<p><b>ABSTRACT</b><br>
In this paper, we study the noise attenuation in poroelastic liners exposed to grazing flow. The acoustic propagation in the liner and in the aeroacoustic domain are respectively governed by Biot’s model and Galbrun’s equation. Here, the coupling between Galbrun’s and Biot’s equation is realized with a mixed pressure-displacement finite element method. This formulation is quite natural since both equations have an efficient formulation in this form. On the one hand, mixed formulation is used in Galbrun’s equation to avoid numerical locking, in the other hand, this is useful in poroelasticity to save degrees of freedom. Under the assumptions there is no flow in the liner and uniform mean flow in the acoustic domain, this method is validated by an analytic method in an infinite duct.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p558.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p117" class="affilation"></a>Computation of Indirect Combustion Noise by a CAA-Method</h2>
<h3>Christoph Richter, Frank Thiele</h3>
<p class="affilation">Institute of Fluid Mechanics and Engineering Acoustics, Berlin University of Technology, Germany</p>
<p><b>ABSTRACT</b><br>
The available theory for indirect combustion noise, which was mainly developed in the seventies of the last century, is reviewed from the standpoint of current methods in Computational-Aeroacoustics. The basic idea therefore - the modes of perturbation which a fluid can show ---goes back to the fifties. The coupling of these modes is then investigated with respect to a typical-combustion system. An energy cascade for the generation of acoustic energy is found. It is-fed by non-acoustic perturbations interacting with the mean flow in the turbine stages. Indirect-combustion noise is shown to be an important noise source. Finally, the qualitative theoretical-results are compared to a simplified numerical experiment. The numerical model needs to be-non-dispersive with respect to small scale entropy perturbations. Furthermore, the correct modeling-of the flow ranging from nearly resting incompressible to transonic conditions is required.-Additionally, the reflections of the combustion system have to be considered to get a realistic-response. The theoretically predicted effects are observed with the simulation.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p117.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p260" class="affilation"></a>Validation of an Innovative Hybrid Method for the Prediction of Noise Generated by Confined Flows</h2>
<h3>Christophe Schram, Michel Tournour</h3>
<p class="affilation">CAE Division, LMS International, Interleuvenlaan 68, Researchpark Haasrode Z1, 3001 Leuven, Belgium</p>
<p><b>ABSTRACT</b><br>
In this work we are concerned with noise generation by confined flows: HVAC systems, automotive exhaust systems (mufflers), and industrial fluid distribution systems. We are aiming at predicting the generation and propagation of flow-induced noise in ducts with arbitrary geometries, and for frequencies high enough for transverse modes to be cut-on. Curle’s analogy was shown to perform poorly in such configurations, when applied using incompressible or low-order compressible CFD data as input. We have developed an innovative hybrid method, based on the combination of Curle’s analogy with a Boundary Element Method, to compensate for the weaknesses of Curle’s analogy in such applications. The originality of the method stands in its decoupling between hydrodynamic and acoustical informations at the wall. This method is validated by application to a test case: the sound emitted by a co-rotating pair of vortex filaments leapfrogging in an infinite 2D duct. Our results show a remarkable agreement with a reference solution based on the duct modes, thereby validating our approach.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p260.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p333" class="affilation"></a>Noise Prediction of a Serrated Nozzle Using a Hybrid Approach</h2>
<h3>Dandy Eschricht (1), Lukasz Panek (1), Jianping Yan (1), Frank Thiele (1), Marc Jacob (2)</h3>
<p class="affilation">(1) Institute for Fluid Mechanics and Engineering Acoustics (ISTA), Berlin University of Technology, 10623 Berlin, Germany (2) Ecole de Centrale de Lyon, Lyon, France</p>
<p><b>ABSTRACT</b><br>
In this work simulation and far-field sound prediction results are presented for a number of subsonic, coaxial jet flow configurations of high Reynolds number. Two casing geometries have been examined, and in both cases the nozzle lip of the outer nozzle was studied with and without serrations. The unsteady Reynolds-Averaged-Navier-Stokes Equations have been solved using a finite volume solver. A modified version of the Detached Eddy Simulation (DES) has been applied to model unresolved turbulence. The DES is based on a two equation turbulence model with a modified length scale definition. Far-field acoustic results were obtained using the acoustic analogy of Ffowcs-Williams & Hawkings. The predicted overall sound pressure levels agree well with measurements, while deviations are within a 3dB range, meaning that the dominant noise sources have been captured in the simulation on relatively coarse grids.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p333.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p407" class="affilation"></a>Applications of a Finite-Element Mode-Matching Method to Acoustic Design of the Bypass Duct of Turbofan Engines</h2>
<h3>G. Gabard, R. J. Astley</h3>
<p class="affilation">Institute of Sound and Vibration Research, University of Southampton, Southampton, SO17 1BJ, U.K.</p>
<p><b>ABSTRACT</b><br>
A finite-element mode-matching approach for duct acoustics with flow and circumferentially varying liners is presented. This general prediction method comprises two stages. The first stage is a fully numerical procedure to determine the acoustic modes in ducts of arbitrary cross-section and mean flow profiles. The second stage is a numerical mode-matching method using a modified matching technique in order to deal more accurately with liner discontinuity with flow. By matching modal expansions at the interface between different uniform duct segments, the effect of axial variations of impedance can be modeled with far fewer parameters than would be required for a 3-D numerical transmission analysis. An analytic radiation model can also be integrated with the mode-matching procedure in order to obtain far-field directivity for tones and broadband multi-mode noise. Validation results of the method using analytical results are presented. An application of particular interest to the acoustic design of turbofan engines is the effect of hard patches in lined bypass ducts. These hard patches are introduced to meet other mechanical or aerothermal design requirements but deteriorate the performance of acoustic treatments by reducing the liner area and by introducing significant modal scattering inside the duct. A parametric study of the geometry of a rectangular hard patch in a straight annular duct was carried out using the finite-element mode-matching method. The effect of the hard patch is discussed both in terms of modal scattering inside the duct and in terms of noise radiated to the far field.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p407.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p432" class="affilation"></a>A Selective Overview of High-Order Finite Difference Schemes for Aeroacoustic Applications</h2>
<h3>I. Spisso, A. Rona</h3>
<p class="affilation">Department of Engineering, University of Leicester, Leicester LE1 7RH, United Kingdom</p>
<p><b>ABSTRACT</b><br>
A variety of aeroacoustic problems involve small-amplitude linear wave propagation. High-order schemes have the accuracy and the low dispersion and dissipation wave propagation properties that are required to model linear acoustic waves with minimal spatial resolution. This review presents a selection of high-order finite difference time-explicit schemes for aeroacoustic applications. A scheme selection method based on the computational cost for a given accuracy level is proposed.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p432.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p183" class="affilation"></a>Critical Issues in Experimental Jet Aeroacoustics</h2>
<h3>K. Viswanathan</h3>
<p class="affilation">The Boeing Company, M/S 67-ML, PO Box 3707, Seattle, WA 98124, USA</p>
<p><b>ABSTRACT</b><br>
Experimental investigations, both at model and engine scales, constitute the primary means of gaining quantitative and qualitative information on jet noise, because a complete theory capable of predicting the spectral characteristics at all radiation angles is not available even for the simplest geometry of a round jet. It is of paramount importance then to ensure that the experimental measurements are accurate and free of extraneous contamination. Issues that are important for jet aeroacoustic tests and the critical role of good data in the development of jet noise technology are reviewed and discussed. With careful consideration of several factors in the design of both the jet rig and the instrumentation system, the pitfalls associated with testing can be avoided. Given the high cost and complexity of full-scale tests, model scale tests are preferred. Several issues need to be addressed first, before comparisons of model data with engine data can be made. These pertain to the noise measurement system, effects of the flow state and conditions at the nozzle exit, effects of Reynolds number, atmospheric attenuation corrections, scaling, etc. These issues are examined in detail with concrete examples. Aeroacoustic measurements in a well-controlled anechoic facility have been made over a wide range of jet conditions; these include thrust performance, far-field spectra, as well as the location of acoustic sources using a directional microphone system. Details of a special test, carried out with the goal of measuring pure jet noise from a jet engine at all angles, are provided. With proper scaling, both narrowband and one-third octave spectra can be collapsed. Excellent agreement between scaled model and engine spectra is demonstrated at all angles and frequencies for a variety of power levels. It is firmly established that jet noise research carried out at model scale is applicable to jet engines.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p183.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p369" class="affilation"></a>Diagnostics of Aero-Acoustic Performance of Forward Slanted Perforated Tube</h2>
<h3>Kunisato Seto (1), Md. Tawhidul Islam Khan (1), Kenbu Teramoto (1), Hiromiostu Ohta (2)</h3>
<p class="affilation">(1) Department of Mechanical Engineering, Saga University, 1 Honjo-machi, Saga, 840-8502, Japan (2) Dept. of Mechanical Engineering, National Fishery University, Shimonoseki, 759-6595, Japan</p>
<p><b>ABSTRACT</b><br>
The aero-acoustic performance of a forward-slanted perforated tube with different perforation patterns and different porosities has been theoretically evaluated and diagnosed. We have already reported that a forward slanted perforated tube has a better performance of noise reduction of supersonic jets than the tubes of backward-slanted perforations and normal perforations to the tube axis. The only drawback of the tube with forward-slanted perforation was found to generate a tonal component at low pressure. However, that problem also has been overcome partly by removing the sharpness of the inner surface of the perforations. Again to improve the efficiency of the forward slanted perforated tube in noise suppression, the perforation patterns (alternate and parallel) have been changed. Moreover, the numbers of perforation as well as the porosities of the forward slanted tubes were modified again to improve the performance of the tube and found the reasonable results. In the present report, we analyzed the thrust loss of different types of forward slanted perforated tubes for various porosities and different perforation patters and identified a suitable type of forward slanted perforated tube which prevented the generation of peculiar tone at a wider range of pressure. The aero-acoustic performance has been diagnosed from the view points of sound pressure level and thrust. All experiments were conducted inside an anechoic chamber. Acoustic data were taken by 8-channel data acquisition devises along with other apparatus and the jet structures were observed by Schlieren apparatus along with high-speed video camera. Thrust loss was measured through a vertical wind tunnel to receive the data directly.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p369.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p204" class="affilation"></a>Noise Reduction of Handheld Vacuum Cleaners According to Geometric Optimization of Air Passages</h2>
<h3>M. J. Mahjoob, H. Ashrafi</h3>
<p class="affilation">Noise, Vibration, Acoustics (NVA) research Center, School of Mechanical Engineering, Univ. of Tehran</p>
<p><b>ABSTRACT</b><br>
This project has been done with joint cooperation of Pars Khazar industrial group - Nur Toushe home appliances company and NVA research center of the university of Tehran on the HVC412 commercial product. Each part of the vacuum cleaner assembly is geometrically optimized according to fluent streamlines in order to minimize the noise level. In this procedure it is attempted to avoid most important aero-noise generating mechanisms such as : turbulence , rapid air passage changes , impact , sudden exhausting traps , cavity noise and etc. In addition to noise reduction of the product the main purpose was to increase the vacuum pressure of the device. In each segment prototypes of concerned parts have been made and tested in various conditions. Tests results include noise level reduction and vacuum pressure increase.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p204.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p282" class="affilation"></a>Effect of Boundary Conditions and Source Truncation in the Prediction of Flow-Generated Sound</h2>
<h3>Paula Martinez-Lera (1), Julien Christophe (2), Christophe Schram (1), Jerome Anthoine (2)</h3>
<p class="affilation">(1) LMS International, 3001 Leuven, Belgium (2) von Karman Institute for Fluid Dynamics, 1640 Rhode-St-Genese, Belgium</p>
<p><b>ABSTRACT</b><br>
The influence of the finiteness of the source domain on the application of Curle’s analogy for the computation of flow-generated sound is investigated in the present work. Two aspects are studied: the spurious source of sound induced by CFD boundary conditions in incompressible simulations and the error due to the truncation of the integration source domain. Two validation cases are investigated: a synthetic vortex street and the flow past a confined cylinder, both at low Mach number. The confined flow case presents specific difficulties, related to the presence of boundaries in the near-field of the quadrupolar sources and the existence of dipolar sources.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p282.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p819" class="affilation"></a>Predicting and reducing aircraft noise</h2>
<h3>R.J. Astley, A. Agarwal, K.R. Holland, P.F. Joseph, R.H. Self, M.G. Smith, R. Sugimoto, B.J. Tester</h3>
<p class="affilation">Institute of Sound and Vibration Research
University of Southampton
Southampton SO17 1BJ
UK</p>
<p><b>ABSTRACT</b><br>
The aircraft noise problem is defined and the engine and airframe sources which contribute to it are described. The international framework for assessing and measuring aircraft noise is outlined, and the use of Effective Perceived Noise Level (EPNL) as a measure of aircraft noise is related to the engineering task of developing technologies to reduce noise. The considerable progress that has been made in reducing aircraft noise over the last four decades is reviewed and the targets which have been set in Europe for further noise reduction by 2020 are discussed. The state of the methods currently available for predicting the different elements of whole aircraft noise is presented and their effectiveness is reviewed in four specific areas; fan and turbine noise, jet noise, airframe noise and installation effects. Noise reduction technologies which have been developed or are currently being developed are also presented. More radical measures which may be needed to address the the problem in the longer term are also touched upon.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p819.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p588" class="affilation"></a>Stepwise Air Flow in the Gravity Draught Aeroacoustic Tunnel</h2>
<h3>Radu Dan Rugescu</h3>
<p class="affilation">Department of Aerospace Engineering, Texas A&M University, 701 H. R. Bright Building, Ross St, 3141 TAMU, College Station, TX 77843, USA</p>
<p><b>ABSTRACT</b><br>
Numerical simulation of non-isentropic and discontinuous unsteady flows with energy addition or extraction, during ignition of solid propellant rocket motors was modified to simulate transients of the airflow in tall solar towers based on the wave front method. Zannetti previously used this method for isentropic flows in high-speed aerodynamics. Its application in discontinuous flows through equation change and local energy extraction also proves highly efficient. Computational efficiency is demonstrated by CFD simulation of the starting transients in solar towers and the WINNDER aeroacoustic wind tunnel in particular. The 1-D methodology and numerical code are especially suited for unsteady flows in slender channels, where the ratio between the length of the duct and its diameter is high. The wave front model scheme covers the dual behaviour of the fully non-isentropic flow in the heat exchanger and the isentropic flow through the test chamber. Code robustness is demonstrated during runs on the PC. The 1-D numerical scheme is based on resolution of gasdynamic discontinuities within the enhanced method already proven for solid propellant rocket motors.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p588.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p417" class="affilation"></a>Predictions of Fan Broadband Noise Due to Rotor-Stator Interaction</h2>
<h3>Vincent Jurdic (1), Phillip Joseph (1), Antoine Moreau (2), Lars Enghardt (2)</h3>
<p class="affilation">(1) ISVR, University of Southampton, University road, Southampton SO17, England (2) German Aerospace Center (DLR), Institute of Propulsion Technology, Engine Acoustics Branch, Müller-Breslau-Str. 8, 10623 Berlin, Germany</p>
<p><b>ABSTRACT</b><br>
This paper presents a comparison of the predicted and measured broadband noise generated in a low-speed fan rig. It is assumed that the dominant noise generation mechanism is rotor-stator interaction whereby turbulent wakes from the rotor interact with the downstream stator. The stator is modelled as a cascade of flat plate airfoils. The acoustic response of these blades is predicted using classical theory for the acoustic response due a rectilinear cascade of flat plate airfoils in which a harmonic (single-frequency, single-wavenumber) gust is incident. This theory has been extended to predict the broadband noise generated by impinging homogenous isotropic turbulence. The present paper proposes a comparison between measured and predicted noise power spectra. Aerodynamic measurements have also been performed at different radial positions downstream of the rotor to obtain velocity spectra and wake profiles. The aerodynamics measurements will be presented in this paper to validate the assumptions of homogenous isotropic turbulence made in the noise model. From these measurements, the turbulence intensity and length scale at the stator leading edge are also determined as input quantities to the noise model.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p417.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p423" class="affilation"></a>A Simple Formula for Predicting the Reverberation Time in Long Enclosures</h2>
<h3>C. Y. C. Lai (1), K. M. Li (2)</h3>
<p class="affilation">(1) Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hung Hom, Hong Kong (2) Ray W. Herrick Laboratories, School of Mechanical Engineering, Purdue University, IN 47907-2031, USA</p>
<p><b>ABSTRACT</b><br>
Reverberation time is one of the key elements for assessing the perception of sound in an enclosed space. It affects the noise propagation, speech intelligibility, clarity index, and definition. Since sound field in the long enclosure is non diffuse, classical room acoustics theory does not apply in long enclosures. Since 1960s, a number of theoretical investigations relating to sound propagation in long enclosures have been carried out but most of theses formulations are time consuming and too complex for routine use at a preliminary design stage. In order to simplify the numerical analysis, a simple yet sufficiently accurate numerical formula is developed that can be used to predict the reverberation time with a simplified formulation. Field measurements have been conducted in a model tunnel and a long corridor to explore the validity of the proposed numerical scheme.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p423.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p631" class="affilation"></a>Implementation of the Uniform Theory of Diffraction in the Phased Beam Tracing Method</h2>
<h3>Cheol-Ho Jeong, Jeong-Guon Ih</h3>
<p class="affilation">Center for Noise and Vibration Control (NoViC), Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Science Town, Daejeon 305-701, Korea</p>
<p><b>ABSTRACT</b><br>
The phased beam tracing method (PBTM), which introduces the phase information into the geometrical acoustic technique, has a definite advantage in simulating the interference of waves at medium frequencies in an enclosed space. Generally, the diffraction effect cannot be included due to the straight propagation of triangular beams. However, the diffraction should be considered in, particularly, near corners, edges, and obstacles at low frequencies. To resolve the problem, the uniform theory of diffraction (UTD) was integrated into the PBTM to predict the low frequency response near a step discontinuity. Using the UTD, we could remove the singularity in the diffraction coefficient near shadow and reflection boundaries. Single and double diffraction were included to correct the conventional PBTM results at low frequencies. The simulation showed a good agreement with previous research and the measurement. The simulation shows a good agreement with previous work and measurement. It is though that the PBTM combined with the UTD can be a fast and efficient acoustic prediction tool in an enclosure at low and mid frequencies.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p631.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p112" class="affilation"></a>Effects of Reverberation Time and Sound Source Characteristic to Auditory Localization in an Indoor Sound Field</h2>
<h3>Chiung Yao Chen</h3>
<p class="affilation">School of Architecture and Urban Design, Chaoyang University of Technology, Wufeng, Taichung, Taiwan</p>
<p><b>ABSTRACT</b><br>
According to the reports by Morimoto (1989) regarding the influences of the sound localization of spatial perception in a hall, the reverberation energy (RT60 = 0.3, 0.9 sec) may be treated as the first reflection energy (delay time = 80, 160ms). However, the selection of music is exclusively limited to using Wolfgang Amadeus Mozart’s Symphony No. 41, Movement IV as a music source. We intended to prove that the sensitivities on sound localization of spatial impression will vary depending on the structural characteristics of music. Therefore, the other three sound sources: Motif A (Royal Pavane by Gibbon, τe = 127 ms), Motif B (Sinfonietta, Opus 48; III movement; Allegro con brio by Arnold, τe = 35 ms) and Speech (female, τe = 23 ms) were adopted. According to the sound field design theory described by Ando (1985)2, the determining factor of an ideal reverberation time length lies in the effective delay of autocorrelation function (τe) of sound sources. The reverberation time of our experiments was set at: short (0.3 sec.), medium (0.9 sec.) and long (2.0 sec.) respectively. The judgments of the apparent sound localization were responded from 12 participants by way of scaling using a normal distribution between two horizontal stimuli angles. The result shows that Motif A obtained the highest accuracy level while speech hit the lowest (p < 0.01). The primary cause was the different τe proposed by Ando (1985); namely, the significant difference sensation of reverberate image between motifs will have an influence on human’s auditory spatial perception of sound source. Furthermore, with respect to the reverberation time, no difference in spatial perception influence was obtained here.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p112.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p203" class="affilation"></a>A Review of Residential Balconies with Road Traffic Noise</h2>
<h3>Daniel Naish, Andy Tan</h3>
<p class="affilation">Built Environment and Engineering, Queensland University of Technology, Brisbane, QLD 4000, Australia</p>
<p><b>ABSTRACT</b><br>
The acoustics of residential balcony spaces in the presence of road traffic noise has been investigated by several authors over a period of several decades. However it would appear there remains an absence of a simple and yet reliable method to predict the acoustics of balcony spaces. There are two primary elements requiring consideration. The first element is to predict road traffic noise levels spatially across the balcony for the function of outdoor noise criteria compliance. The second element is to predict the road traffic noise level on the external facade of the room behind the balcony to assist in the design of facade sound isolation requirements. This paper reviews the methods and results of the key literature available on the acoustic properties of residential balconies in the presence of road traffic noise.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p203.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p625" class="affilation"></a>Research of Auralization in Small Enclosures</h2>
<h3>Fangli Ning (1), Geng Liu (1), Juan Wei (2)</h3>
<p class="affilation">(1) College of Mechanical and Electrical Engineering, Northwestern Polytechnical University, Xi’an, P.R. China (2) State Key Lab.of Integrated Service Networks, Xidian University, Xi’an, P.R. China</p>
<p><b>ABSTRACT</b><br>
Auralization is front edge research in architectural acoustics. In real life, human main living areas are Small enclosures, such as living room, work room, car cab, ect. Because of wavelength of sound in low frequency being close to dimensions of small enclosures, scattering and diffraction in the course of sound radiation couldn’t be ignored. As a result, auralization based on geometrical acoustics can’t be applied in small enclosures. In this paper, firstly, based on Helmholtz equation and its boundary equations, model of Finite Element Method (FEM) is given for computing low frequency sound transfer function in small enclosures. Secondly, procedures for the realization of auralization software in small enclosures are presented in detail. Lastly, as an example, the auralization is realized in one car cab model.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p625.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p621" class="affilation"></a>Acoustic Tests on Original Concrete and Inert Mixture Materials</h2>
<h3>Franco Cotana (1), Federico Rossi (2), Andrea Nicolini (1), Sofia Simoni (2)</h3>
<p class="affilation">(1) University of Perugia - Industrial Engineering Department, Via G. Duranti 67, 06125, Perugia, Italy (2) University of Perugia - Industrial Engineering Department, Loc. Pentima Bassa 21, 05100, Terni, Italy</p>
<p><b>ABSTRACT</b><br>
In this paper an innovative concrete and inert mixture is proposed to assemble building partition walls. Mixture is made for no-structural light concrete by aggregating concrete with natural and artificial inerts. Pumice, lapillus and rubber are employed as inerts. A measurement campaign was carried out to evaluate the materials acoustic properties for different samples composition. Experimental tests were realized by an impedance tube: transmission loss was evaluated by a four microphone transfer function method, based on ISO 10534-2. Test results are here reported. Measurements results allows to determine the optimum mixture in term of acoustic properties.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p621.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p28" class="affilation"></a>Acoustics in Large Atrium Spaces</h2>
<h3>Jian Kang, Ling Yap, Yan Meng, Bing Chen</h3>
<p class="affilation">School of Architecture, University of Sheffield, Sheffield S10 2TN, UK</p>
<p><b>ABSTRACT</b><br>
Many public buildings, such as shopping centres, airports, railway stations, hotels, and certain residential buildings, contain large atrium spaces, where the sound fields are usually not diffuse and thus the classic Sabine/Eyring theories are often inapplicable. This study aims to systematically examine the basic characteristics of sound fields in such spaces, and also to explore appropriate methods of calculating relevant acoustic indices. The acoustic comfort in such spaces and its relationships with the sound fields are also considered. In a number of typical large atrium spaces, objective measurements including reverberation as well as spatial and temporal sound distribution were made, and subjective evaluation of acoustic comfort were also carried out. It has been shown that with different source-receiver locations, the variation in reverberation is significant whereas the spatial sound distribution is relatively even. The Sabine formula could be used for predicting average reverberation time in the whole space, but for individual source-receiver positions computer simulation is essential. The acoustic comfort study suggests that the current acoustic conditions need to be improved.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p28.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p426" class="affilation"></a>Transmission of Sound in a Long Enclosure with a “T” Intersection</h2>
<h3>S. T. So (1), W. S. Fung (1), C. W. Leung (1), K. M. Li (2)</h3>
<p class="affilation">(1) Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hung Hom, Hong Kong (2) Ray W. Herrick Laboratories, School of Mechanical Engineering, Purdue University, IN 47907-2031, USA</p>
<p><b>ABSTRACT</b><br>
Bends, T-intersections, U-shape turns and cross-junctions are some variations that can be found frequently in long enclosed spaces. For a receiver located around the bend in the “T” intersection, the total sound pressure consists of contributions from direct, reflected and diffuse sound waves. The direct sound contribution is dominant in the near fields in the region of sight-lines. The reflected sound field becomes more important as the receiver moves farther away from the corner of the intersection. In all cases, the diffracted sound field at the edge of the bend plays a relatively minor role along a long enclosure. The present study examines the transmission of sound along a tunnel with a “T” intersection. The characteristics of the sound fields are investigated theoretically and experimentally. A numerical model, known as an image source method, has been developed for the prediction of sound transmitted around the corner in the “T” intersection. In the numerical scheme, the phase and magnitude of all contributions from the direct and reflected waves have been included in the calculations. Indoor experiments have been carried out in a corridor with a “T” intersection for validating the theoretical formulation. Experimental results and numerical predictions for the transmission of sound of this configuration in a long enclosure are presented in this paper.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p426.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p440" class="affilation"></a>Time Domain Large-Scale Finite Element Sound Field Analysis of a Multi-Purpose Hall</h2>
<h3>Toru Otsuru (1), Takeshi Okuzono (1), Noriko Okamoto (1), Kota Isobe (1), Hiroshi Furuya (2)</h3>
<p class="affilation">(1) Department of Architecture and Mechatronics, Oita University, 700 Dannoharu, Oita, 870-1192, Japan (2) Department of Architecture, Kyushu Kyoritsu University, 1-8 Jiyugaoka, Kitakyushu, 807-8585, Japan </p>
<p><b>ABSTRACT</b><br>
The authors have been developing Large-scale Finite Element Sound Field Analysis, or LsFE-SFA for short, to analyze sound fields in architectural rooms with complicated boundary conditions. The main purpose of this paper is to show its applicability and accuracy when a realistic large-scale sound field is to be analyzed in the time domain. A multi-purpose hall(A-hall, for short) with the volume of more than 37,000 m<sup>3</sup> and about 2,500 seats is analyzed hereafter. At first, both mathematical basis of time domain LsFE-SFA is explained briefly. Then, both frequency and time domain LsFE-SFA were applied onto the sound field in A-hall. In the analyses, two types of boundary modeling, with or without balcony, were given into the computations. The values of absorption coefficient of materials except auditorium side-walls were given by referring literatures, and that of side-walls were given by in-situ measurement following some of the authors’ EA-Noise method. By the frequency domain LsFE-SFA, sound pressure level distribution contour maps at 63 and 125 Hz were computed and the results were confirmed to be good. Then, the 1/3 octave band filtered impulse responses centered at 63 Hz and 125 Hz were computed by the time domain LsFE-SFA, and fair agreements with measured data were found. Finally, the results by the time domain LsFE-SFA were transformed into the frequency domain and the relative sound pressure level distributions of them showed excellent agreement with those computed by the frequency domain LsFE-SFA directly.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p440.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p155" class="affilation"></a>Numerical Study of Structural Vibration Induced by Combustion Noise - One Way Interaction</h2>
<h3>Artur K. Pozarlik, Jim B. W. Kok</h3>
<p class="affilation">Laboratory of Thermal Engineering, University of Twente, P.O.Box 217, 7500 AE Enschede, The Netherlands</p>
<p><b>ABSTRACT</b><br>
The turbulent flame in the lean combustion regime in a gas turbine combustor generates significant thermo-acoustic noise. The thermo-acoustic noise induces liner vibrations that may lead to fatigue damage of the combustion system. This phenomenon is investigated in the project FLUISTCOM using both an experimental and a numerical approach. The correlation between acoustic pressure oscillations on one side and liner vibrations on the other side is a prime interest. In order to have better insight in the processes present in the combustion chamber, a combustion test rig was designed and manufactured at the University of Twente. One of the most important parts of the test rig is a liner with a flexible section and optical access to measure the vibration pattern and amplitude. This paper describes a flame investigated at 1.5 bar, 125 kW with premixed natural gas and air. The experimental measurements of the vibrations are done with the use of a Laser Doppler Vibrometer. CFX-Ansys was used for the transient numerical calculations of the transient combustion flow within the combustion chamber. Simultaneously, the pressure results from the near-wall region were collected and sent as initial conditions to a structural code (Ansys). Results show the one way response of the liner structure as a result of the transient pressure generated by the combustion of the gas flow. The paper will present the numerically predicted results on the combustion field, the accompanying oscillating pressure field, and the induced structural vibration of the combustor liner. These results will be compared with the available experimental data.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p155.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p215" class="affilation"></a>Overview of Different Approaches for Active Control of Combustion Instabilities</h2>
<h3>Ben T. Zinn, Eugene Lubarsky, Yedidia Neumeier</h3>
<p class="affilation">Daniel Guggenheim School of Aerospace Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA</p>
<p><b>ABSTRACT</b><br>
This paper describes three different active control approaches for damping detrimental combustion instabilities that have been investigated at Georgia Tech in recent years. The first approach uses a closed loop active control system (ACS) that consists of a pressure sensor, a real time observer, a controller and a fuel injector actuator. Its unique components are the observer, which determines the characteristics of the most unstable combustor modes within a few (two to five) periods of the oscillations, and the fuel injector that employs a magneto-strictive actuator to modulate the fuel injection rate over a relatively wide range of frequencies. It has been shown that this ACS can effectively damp combustion instabilities over wide ranges of operating conditions on different combustors nearly instantaneously (~40μs). The second ACS damps combustion instabilities by “active” modification of the characteristic combustion time. This is achieved by use of a “smart” fuel injector with capabilities for changing the characteristics of the fuel spray. This, in turn, changes the characteristic combustion time in a manner that prevents coupling between the combustion process and acoustic oscillations, thus damping the instability. The advantage of this approach is that it damps the instability by a “one-time” change of the “smart” fuel injector setting. The third approach actively damps combustion instabilities by open loop, periodic, modulation of the fuel injection rate at frequencies that differ from the instability frequency. It is shown that modulating the fuel injection rate over specific ranges of frequencies results in near complete damping of the instability. Apparently, modulating the fuel injection rate at one of these frequencies “disrupts” the mechanism that drives the instability. While this approach is very effective, the manner in which it “operates” must be elucidated before it is used in practice.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p215.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p235" class="affilation"></a>Active Control of Combustion Instability Using Pilot and Premix Fuel Modulation</h2>
<h3>Daniel Guyot, Matthias Rößler, Mirko R. Bothien, Christian O. Paschereit</h3>
<p class="affilation">Institute of Fluid Dynamics and Engineering Acoustics, University of Technology Berlin, D-10623 Berlin, Germany</p>
<p><b>ABSTRACT</b><br>
Phase-shift control was applied to an atmospheric premix combustor test rig equipped with a swirl-stabilized burner. Actuation was achieved by modulating either the pilot or the premix fuel mass flow. The pilot mass flow was modulated with a standard on-off valve and a high frequency proportional valve. For premix mass flow modulation only the proportional valve was employed. The unsteady pressure signals were processed by the controller and command signals were sent to the valves. The performances of the two actuator set-ups are compared with respect to their ability to dampen thermoacoustic instability and their impact on the combustion system’s emissions. The results confirm the suitability of pilot as well as premix fuel mass flow modulation for reducing thermoacoustic instability in a lean premix combustor. Additionally, stabilizing the combustion process also resulted in reduced NOX emissions, but on the other hand increased CO<sub>2</sub>.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p235.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p420" class="affilation"></a>Application of Modal Parameter Derivation in Active Suppression of Thermo Acoustic Instabilities</h2>
<h3>J. D. B. J. van den Boom, I. Lopez, V. N. Kornilov, L. P. H. de Goey, H. Nijmeijer</h3>
<p class="affilation">Department of Mechanical Engineering, Eindhoven University of Technology, P. O. Box 513, 5600 MB Eindhoven, The Netherlands</p>
<p><b>ABSTRACT</b><br>
Low NO<sub>x</sub> premixed surface burners are often applied in modern central heating systems. Systems equipped with these burners often experience noise problems. In order to make any further advance in the development of these systems these problems have to be solved. Therefore, the feasibility of model-based control strategies in suppressing the (thermo acoustic) instabilities is investigated. Based on an acoustic network approach, a model for the gas-fired boiler is derived. Special attention is paid to the flame behavior, since a modal analysis identification method has been used to describe the dynamics. A H<sub>∞</sub> controller is synthesized utilizing this model. The performance of this controller is validated using simulations and compared with a previously derived physical model-based controller.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p420.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p214" class="affilation"></a>The Acoustic Wave Propagation Equation in a Turbulent Combusting Flow</h2>
<h3>Jim B. W. Kok, Bram de Jager</h3>
<p class="affilation">University of Twente, Dept. of Mech Eng., PO Box 217, 7500 AE Enschede, The Netherlands</p>
<p><b>ABSTRACT</b><br>
Sound generation by turbulent flames originates from the fluctuating heat release in the flame. The description of this fluctuating heat release and its effect on acoustics in turbulent flames is complicated due to the interaction of chemical reactions with turbulence, mixing and pressure fluctuations. In a turbulent flame the instantaneous density, velocity, pressure, temperature and species concentrations are determined by the transport equations for mass, momentum, enthalpy and species and by the equation of state. In the proposed paper an equation is formulated that describes the propagation of acoustic pressure fluctuations, and that determines the source terms. Subsequently events are ordered on basis of their typical time scale. That way source terms can be evaluated for the situation where the combustion is described with the use of time averaged chemical reaction progress variables and a mixture fraction variable. Subsequently the consequences of Reynolds and Favre averaging on these source terms and conservation of acoustical variables in a domain with turbulent flow are discussed. The use of the reaction progress variables, as a basis for acoustic propagation prediction, in a Reynolds averaged Navier-Stokes flow calculation, is demonstrated on a premixed turbulent natural gas flame with finite combustion kinetics.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p214.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p121" class="affilation"></a>An Asymptotically Motivated Hyrodynamic-Acoustic Two-Way Coupling for Modeling Thermoacoustic Instabilities in a Rijke Tube</h2>
<h3>Jonas P. Moeck (1), Heiko Schmidt (2), Michael Oevermann (3), Christian Oliver Paschereit (1), Rupert Klein (2)</h3>
<p class="affilation">(1) Institut für Strömungsmechanik und Technische Akustik, Technische Universität Berlin, 10623 Berlin, Germany (2) Fachbereich Mathematik/Informatik, Freie Universität Berlin, 14195 Berlin, Germany (3) Institut für Energietechnik, Technische Universität Berlin, 10623 Berlin, Germany</p>
<p><b>ABSTRACT</b><br>
Thermoacoustic instabilities are a serious problem for lean premixed combustion systems. Due to different time and length scales associated with the flow field, combustion and acoustics, numerical computations of thermoacoustic phenomena are conceptionally challenging. Typically, the Mach numbers in gas turbine combustors are small. Nevertheless, numerical solvers are often based on compressible approaches in order to take into account the effect of the acoustic field. Considering the sensible interaction between chemical source terms and acoustics, spurious waves produced by these solvers may mislead the physical interpretation. For the low Mach number, long wave length case, we propose a bilateral coupling, where the region of heat release is described by a finite-difference zero Mach number solver. The larger acoustic domain is modeled by the common network approach for plane wave propagation. The coupling conditions are based on results from two-scale low Mach number asymptotics. As an example, simulation studies for a Rijke tube exhibiting self-excited oscillations are presented.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p121.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p301" class="affilation"></a>Passive Control of Combustion Induced Noise in an Auxiliary Bus Heating System</h2>
<h3>Jonas P. Moeck (1), Robert Engel (2), Christian Oliver Paschereit (1)</h3>
<p class="affilation">(1) Institut für Strömungsmechanik und Technische, Technische Universität Berlin, 10623 Berlin, Germany (2) Spheros GmbH, Werk Neubrandenburg, 17033 Neubrandenburg, Germany</p>
<p><b>ABSTRACT</b><br>
Combustion instabilities and combustion induced noise are currently a serious problem for industrial and domestic boilers, furnaces and auxiliary heating devices. Interaction of fluctuating heat release and the acoustic field may generate high amplitude pressure oscillations, which have a negative effect on the combustion process and represent a dominant noise source. Although the pressure amplitudes are usually not high enough to cause any structural wear, as in the case of gas turbine combustors, dominant low-frequency sound emission, associated with flame-acoustic interaction, is a source of customer annoyance. In this work, an auxiliary heating system with a thermal power of 30kW was investigated from a thermoacoustic point of view. The objective was to reduce dominant low-frequency noise observed in the far-field. Acoustic measurements were used to determine the cause of those sound field components. It was found that the major noise contribution originated from a resonant quarter-wave mode interacting with the flame. A geometrical modification of the outlet geometry, reducing the reflection of acoustic waves, achieved a significant decrease in the low-frequency noise. As a result of a larger outlet velocity of the new configuration, however, higher frequency components, associated with the exhaust jet, were generated. To suppress the negative effect of higher jet noise without loosing the advantage of reduced combustion induced noise, the outlet geometry was further improved. The final design was shown to suppress the flame associated low-frequency noise and did not significantly increase the jet noise at higher frequencies, thus reducing the overall sound pressure level.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p301.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p711" class="affilation"></a>The Rijke Tube: Green’s Function Approach in the Time and Frequency Domain</h2>
<h3>Maria A. Heckl (1), Michael Howe (2)</h3>
<p class="affilation">(1) Department of Mathematics, Keele University, Staffordshire ST5 5GB, UK (2) College of Engineering, Boston University, 110 Cummington Street, Boston, MA 02215, USA</p>
<p><b>ABSTRACT</b><br>
The Rijke tube is modelled as an open-ended tube with a blockage, jump in cross-section and jump in mean temperature. Its Green function is known in the frequency domain as well as in the time domain. For the time-domain problem, the heat release characteristic has the form of a real function (giving heat release rate in terms of the acoustic velocity at the heat source). An integral equation is derived, which involves this heat release characteristic and the timedomain Green function. The integral equation is solved numerically by an iteration, stepping forward in time to give the time history of the acoustic velocity and of the heat release rate. Both linear and nonlinear heat release characteristics can be studied by this method. For the frequency-domain problem, the heat release characteristic has the form of a transfer function (relating complex velocity amplitudes to complex heat release amplitudes). An equation is derived for the complex eigenfrequencies of the heat-driven oscillation in the Rijke tube. This equation involves the transfer function and the frequency-domain Green function. It is solved numerically to give the frequency and growth rate of any mode in the Rijke tube.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p711.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p141" class="affilation"></a>Experimental Validation of Linear Analysis in Premixed Combustors Supported by Active Control</h2>
<h3>Mirko R. Bothien, Jonas P. Moeck, Christian Oliver Paschereit</h3>
<p class="affilation">Institute of Fluid Dynamics and Engineering Acoustics, Technical University Berlin, 10623 Berlin, Germany</p>
<p><b>ABSTRACT</b><br>
In this work, linear stability analysis of combustion systems is compared to experimental investigations. To predict the flame-acoustic interaction a network model in its most simple form, solely based on experimental data, is set up in state-space notation. It is assessed if the model is capable to accurately predict the transition from stable to unstable conditions. The transition is achieved by actively tuning the downstream reflection coefficient of the combustor. Furthermore, it is examined if the calculated growth rates match those of the experiments in the linear regime. Excellent agreement between computations from the model and experiments are found with respect to the transition and the frequency of the least stable mode.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p141.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p569" class="affilation"></a>Sound Propagation in a Region of Hot Gas Using the DRBEM</h2>
<h3>Rafael Piscoya, Martin Ochmann</h3>
<p class="affilation">University of Applied Sciences Berlin, Department of Mathematics - Physics - Chemistry, Luxemburger Str. 10, 13353 Berlin, Germany</p>
<p><b>ABSTRACT</b><br>
Simulations of the sound from flames inside combustion chambers define their computational domains predominantly inside the chamber, where the main acoustic sources and their interactions with the combustion processes take place. However, the noise pollution is determined by the sound radiated to the outside. Therefore, the prediction of the sound radiation, in particular of the radiation pattern outside the combustion chamber is of great importance, too. Immediately outside the chamber exit, there is a region of hot gas surrounded by homogeneous medium (air at ambient temperature). Knowing one acoustic quantity (pressure, velocity or impedance) at the exterior surface of the combustion chamber including the exit, the sound radiation can be obtained by solving a Helmholtz-Integral-Equation with an additional volume integral over the region of hot gas. Our research intends to study the applicability of the Dual Reciprocity BEM (DRBEM) to solve this problem. In this work, the DRBEM is applied to find the sound radiation of a round flame, modelled as a spherical volume of hot gas with a certain source distribution surrounded by air at ambient temperature. If the sound distribution depends only on the distance to the origin, the 3D-problem can be reduced to a one dimensional problem and analytically solved for specific source distributions. A comparison of the results of the DRBEM with the analytical solution of this spherical configuration is presented here as a test case.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p569.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p110" class="affilation"></a>Experimental Study of the Flame Cone Kinematics of Acoustically Perturbed Premixed Laminar Bunsen Flames</h2>
<h3>V. N. Kornilov, K. R. A. M. Schreel, L. P. H. de Goey</h3>
<p class="affilation">Eindhoven University of Technology, Faculty of Mechanical Engineering, group of Combustion Technology, PO Box 513, WH 2.144, 5600 MB Eindhoven, The Netherlands</p>
<p><b>ABSTRACT</b><br>
The results of a spatially and temporally resolved experimental study of the conical flame front kinematics of acoustically excited flames are presented. The basic assumptions which are widely used in theoretical flame kinematics considerations are verified experimentally. The propagation velocity and spatial evolution of the flame front disturbances are measured. Special attention is paid to the character of the flame end point motion. An elliptical path of the flame end point displacement is measured. The correspondence between the flame area and heat release rate oscillation is confirmed for a frequency range 10-300 Hz. The effect of the flame curvature on the burning rate is examined and is found to be insignificant.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p110.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p169" class="affilation"></a>Succesful Teaching of Experimental Vibration Research</h2>
<h3>A. G. M. Wolbert, P. J. M. van der Hoogt, Z. A. J. Lok, A. de Boer</h3>
<p class="affilation">Department of Mechanical Engineering, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands</p>
<p><b>ABSTRACT</b><br>
For more than 20 years, master students have been offered a practical training on experimental vibration research by the Structural Dynamics & Acoustics Section of the University of Twente. The basic theoretical knowledge, necessary to attend this practical training, is provided for the Master part of their study and it consists of a series of lectures on advanced dynamics, measurement techniques and the concept of modal analysis. The practical training consists of performing vibration experiments on a well defined simple structure. Use is made of a digital signal processing (DSP) Siglab system, together with ME’scope as analysis tool. In order to guarantee maximal transfer of knowledge toward the participants, small groups consisting of two students are formed. These groups are supervised by an experienced tutor, who intensively monitors the progress of the practical training. It lasts one day and the students have to write down their findings in a report. In order to attend the practical training in an efficient way, students have to study the theoretical basics of experimental vibration research in advance. In order to achieve an optimal preparation to the practical, a ‘virtual’ vibration measurement based on Labview is developed for the next academic year. Students will thus be able to run this experiment remotely from behind their PC by activating a real-life test case placed in the laboratory. In this paper the content and execution of the practical training is described. The experience of the authors is that the vast amount of interesting educational ingredients contributes to a profound understanding of both theoretical and experimental vibration research for Mechanical Engineering students.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p169.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p523" class="affilation"></a>A Tempus Experience: New Curriculum in Sound and Vibration Control in Egypt</h2>
<h3>Tamer Elnady (1), Hans Bodén (2)</h3>
<p class="affilation">(1) ASU Sound and Vibration Lab., Faculty of Engineering, Ain Shams University, Abbaseya, 11517 Cairo, Egypt (2) Department of Mechanical Engineering, The Royal Institute of Technology, 100-44 Stockholm, Sweden</p>
<p><b>ABSTRACT</b><br>
The reduction of noise is of environmental and strategic importance for Egypt. Noise and acoustic annoyance is considered to be a dominant source of pollution within the Egyptian community. A need to develop and strengthen education and specialization in Sound and Vibration Control was therefore identified by Ain Shams University (ASU) in Cairo. The main objective was to produce a new generation of engineers capable of performing constructive research and development in the acoustics and vibrations field. They should be able to select the appropriate hardware to accurately measure acoustic parameters, perform experiments, to come up with better solutions, analyse and simulate acoustic changes and contribute to better understanding of the noise problem. This paper describes the activities of a project funded from the European Commission through the Tempus Program. The project was implemented at Ain Shams University in cooperation with KTH (the Royal Institute of Technology) in Sweden, and ISVR (the Institute of Sound and Vibration Research) in United Kingdom. The project addressed three levels of education: undergraduate, postgraduate students and engineers already working in the industry. The activities of the project included: Improving and updating the courses at ASU - Introducing new teaching methodologies aiming at elaborating more interaction between teachers and students - Establishing a new Sound and Vibration Laboratory. The main aim is to give all students the opportunity to do measurements themselves in order to get better feeling of different phenomena - Train the current teachers and university staff on the new courses, methodologies and equipment - Offer retraining and support for engineers working in the field of sound and vibration to update their. In addition to the main goals, other advantages followed. These include the establishment of the Acoustical Society of Egypt, close collaboration between consortium member universities, and strengthening the link between Egyptian Universities, industries and research institutions.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p523.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p256" class="affilation"></a>Flexural Vibration Band Gaps in Periodic Pipe System Conveying Fluid</h2>
<h3>Dianlong Yu, Jihong Wen, Yaozong Liu, Jing Qiu</h3>
<p class="affilation">Institute of Mechatronic Engineering, and PBG Research Center, National University of Defense Technology, Changsha 410073, China</p>
<p><b>ABSTRACT</b><br>
Flexural vibration in the periodic pipe system conveying fluid is studied in this paper. Using the transfer matrix method, the complex band structure of the flexural wave is calculated to investigate the gap frequency range and the vibration reduction in band gap. And the complete flexural vibration band gaps exist in the piping system with fluid loading. The effect of the fluid on the gaps is considered. The existence of flexural vibration gaps in periodic pipe with fluid loading gives a new idea in vibration control of pipe.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p256.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p353" class="affilation"></a>Non-Periodic Locally Resonant Sonic Materials</h2>
<h3>H. M. Dai, Kin Ming Ho, Z. Yang, P. Sheng</h3>
<p class="affilation">Department of Physics, Hong Kong University of Science and Technology, Clearwater Bay, Kowloon, Hong Kong</p>
<p><b>ABSTRACT</b><br>
Locally resonant sonic materials (LRSMs) are a new class of meta-materials that can block sound waves well beyond the limit of the conventional mass density law. The LRSMs reported so far are made of local resonators arranged periodically in a matrix, although the period is usually much smaller (< 1/20) than the wavelength in the matrix material. At resonance, the effective wavelength becomes much smaller, and the interference from the individual resonators could become significant. Here we report further study of the properties of LRSMs. We found that in some deliberately structured LRSMs the main acoustic properties is determined only by the resonators, independent of their spatial arrangement. In particular, the acoustic properties of a single resonator resemble that of an assembly of the resonators. The lateral coupling of resonators, when deliberately introduced, generates multimode resonances, leading to multiple stop bands in transmissions. The dependence of the resonant frequency f on the mass of the weight M in the single-weight resonator follows the simple mass-and-string relation, namely f ∝ 1/ M<sup>1/2</sup> . The large phase shift associated with the transmission peak that accompanies the stop band provides an approach for designing zoneplates to focus low frequency sound waves, in much the same way as optical zoneplates. Simple estimations show that effective focusing could be achieved for a plate of the diameter of one wavelength and phase shift difference of less than 110 degrees across different zones.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p353.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p329" class="affilation"></a>Wave Propagation in Thin Orthotropic Media</h2>
<h3>Jan Cerv, Frantisek Vales, Pavla Dvorakova, Tomas Kroupa</h3>
<p class="affilation">Institute of Thermomechanics AS CR, v.v.i., Department of Impact and Waves in Solids, Dolejskova 5, 182 00 Prague 8, Czech Republic</p>
<p><b>ABSTRACT</b><br>
Wave motion in a fibre-reinforced thin orthotropic laminate is studied in the paper. A thin panel made of laminate is loaded in-plane by stress pulses. Theoretical solution is based on finite element approach. Experimental solution utilizes for noncontact measurements a laser vibrometer. It was found out that there are some discrepancies between theory and experiment. It turns out that elastic constants given by the producer of the laminate are somewhat incorrect. Measurements performed during these days indicate e.g. difference between Young’s moduli in the direction of fibres about 10%. Further research is in progress.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p329.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p257" class="affilation"></a>Directional Propagation Characteristics of Flexural Wave in Two-Dimensional Periodic Grid-Like Plate Structures</h2>
<h3>Jihong Wen, Dianlong Yu, Yaozong Liu</h3>
<p class="affilation">Institute of Mechatronic Engineering, and PBG Research Center, National University of Defense Technology, Changsha 410073, China</p>
<p><b>ABSTRACT</b><br>
The directional propagation characteristics of elastic wave during pass bands in two-dimensional periodic grid-like thin plate are analysed by using the Plane Wave Expansion method to yield the phase constant surface. The directions and regions of wave propagation in the periodic grid-like structure for certain frequencies during pass bands are predicted with the iso-frequency contour lines of the phase constant surface, which are then validated with the harmonic responses of a finite two-dimensional such periodic structure with 15x15 unit cells. These results are useful for controlling the wave propagation in the pass bands of periodic structure.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p257.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p800" class="affilation"></a>Finite Element Modeling of Multi-Layer Composite Plates with Internal Delamination</h2>
<h3>K. Anefaie (1), M. Abd-Rabou (1), N. Bajaba (2)</h3>
<p class="affilation">(1) Department of Mechanical Engineering, King Abdulaziz University, Jeddah, Saudi Arabia (2) Department of Mechanical Technology, College of Technology, Jeddah, Saudi Arabia</p>
<p><b>ABSTRACT</b><br>
A three-dimensional finite element model for the delaminated fiber reinforced composites is developed to analyze the dynamics of multi-layer composite plates with internal delamination. Natural frequency and modal displacement are analyzed for samples with different dimensions of delamination. Numerical results showed a good agreement with the available experimental data and an enhancement of the accuracy of the results when the proposed model is adopted. The results of this study are useful for detecting delamination in multi-layer composite materials.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p800.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p719" class="affilation"></a>Vibration Attenuation in a Periodic Rotating Timoshenko Beam</h2>
<h3>Maged Alaa El-Din, Mohammad Tawfik</h3>
<p class="affilation">Department of Modelling & Simulation in Mechanics, German University in Cairo, Cairo, Egypt</p>
<p><b>ABSTRACT</b><br>
In this study we investigate the effect of abrupt geometric discontinuities on the vibration of a Timoshenko rotating beam. The beam model is created using finite element code developed on MATLAB and stop and pass bands are identified using periodic analysis. The results are verified using published data. Numerical results indicate the effectiveness of such structure configuration on vibration attenuation.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p719.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p148" class="affilation"></a>Vibration of Elastic Rings Excited by Periodically-Spaced Moving Springs</h2>
<h3>Sripathi Vangipuram Canchi (1), Robert G. Parker (2)</h3>
<p class="affilation">(1) Department of Mechanical Engineering, University of California Berkeley, 5146 Etcheverry Hall, Berkeley, CA 94720, USA (2) Department of Mechanical Engineering, Ohio State University, 201 W. 19th Avenue, Columbus, OH 43210, USA</p>
<p><b>ABSTRACT</b><br>
This work investigates parametric instabilities of in-plane bending vibrations of a thin elastic ring subject to forces from discrete rotating springs of arbitrary number, spacing, and orientation. Several configurations are examined, including systems with symmetric and asymmetric circumferential spring spacing. The method of multiple scales is applied to analytically identify instability boundaries as closed-form expressions, and two different numerical approaches are used to verify these results. The effects of different system parameters on the instability boundaries are studied analytically: the bending stiffness of the ring, the number of springs, and their stiffness, location, orientation and rotation speed. For several cases, well-defined properties for the occurrence or suppression of instabilities are obtained as simple relations in the system parameters.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p148.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p250" class="affilation"></a>Acoustic Wave Propagation Modeling for Periodic Structures as Applied to Anechoic Coating Design</h2>
<h3>Sven Ivansson</h3>
<p class="affilation">Department of Underwater Research, Swedish Defence Research Agency, Stockholm, SE-16490, Sweden</p>
<p><b>ABSTRACT</b><br>
A thin rubber coating with cavities in a doubly periodic lattice can redistribute sound energy, normally incident on a steel plate, in the lateral direction. An anechoic effect appears by absorption in the surrounding rubber. This effect is modeled and studied by adapting modern semianalytical computation techniques for electron scattering and band gaps in connection with photonic and phononic crystals. In comparison to more flexible but also more computer intensitive methods, such as FEM modeling, there are two advantages. First, an improved physical understanding of the anechoic effect can be achieved by simplified semianalytical analysis. The viscoelastic shear-wave properties of the rubber are crucial for generating the desired loss, but compressional-wave absorption can be useful to reduce the reflectance at higher frequencies. The second advantage is the computational speed, which allows modern global optimization techniques to be applied for coating design. Differential evolution algorithms are used to design coatings with significant echo reduction within broad frequency intervals. Computational speed is enhanced by utilizing symmetry properties to reduce the size of the pertinent equation systems. The fastest computations are obtained for spherical cavities of a common size, but extensions to mixed cavity sizes are shown to be possible and useful.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p250.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p307" class="affilation"></a>Experimental Studies on Two-Dimensional Acoustic Defect-Mode Waveguides in a Sonic/Phononic Crystal</h2>
<h3>Toyokatsu Miyashita</h3>
<p class="affilation">Dept. Electronics and Informatics, Ryukoku University, 520-2194, Japan</p>
<p><b>ABSTRACT</b><br>
Two-dimensional acoustic defect-mode waveguides (DMWGs) were constructed by removing every second scatterer from a sonic/phononic crystal along the intended paths for waveguides. The host sonic/phononic crystal was composed of a square array of acrylic resin cylinders in air with a diameter of 5.0 mm. The lattice constant was 6.25 mm with a Bragg reflection at around 27.6 kHz at room temperature. Various shapes of DMWGs were fabricated, namely most simple straight waveguides, a perpendicularly bending one, and a waveguide with a branch or with a crossroads. Their transmission spectra were measured using a network analyzer with a high-frequency speaker, i.e. a tweeter, and a wide-band microphone. The theoretically expected band-pass spectra of DMWGs were confirmed experimentally as follows. (1) A clear 10 dB passband of the straight DMWG was observed between 30.1 and 33.1 kHz with a transmission of -0.52 dB per lattice constant. (2) The transmission was about 0 dB at the center of the passband and about -30 dB at the outside of the passband. (3) The passband was influenced practically neither by the existence of a bend, a branch nor a crossroads in the DMWG. The DMWG was verified to work not only as a novel acoustic waveguide but also as a good band-pass filter.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p307.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p242" class="affilation"></a>An Algorithm for Studying Wave Propagation in Phononic Crystals Composed of Viscoelastic Material</h2>
<h3>Yaozong Liu, Honggang Zhao, Dianlong Yu, Wen Jihong, Xisen Wen</h3>
<p class="affilation">School of Mechantronic Engineering and Automation, National University of Defense Technology, Changsha, Hunan, China</p>
<p><b>ABSTRACT</b><br>
In order to deal with the viscoelasticity of constituents in phononic crystals, an algorithm based on the finite-difference-time-domain method and the numerical approximation of fractional derivative are proposed. It is validated with transfer matrix method which takes the viscosity into account by complex modulus with frequency dependence. Although the viscoelasticity of host material does not influence the frequency position of gaps, a wide transmission gap is found even for very weak viscosity, which gives new idea to design phononic crystals with wide transmission gaps.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p242.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p639" class="affilation"></a>The Affect of the Thessaloniki Ring Road Traffic Noise Emission on Hospitalized Patients in Papageorgiou Hospital</h2>
<h3>Emmanuel Tzekakis (1), Venetia Tsara (2), Vasilis Vasiliadis (1)</h3>
<p class="affilation">(1) Aristotle University of Thessaloniki, Faculty of Technology, Laboratory of Architectural, Technology, 54126 Thessaloniki Greece (2) Thoracic clinic, Papageorgiou Hospital, Thessaloniki Greece</p>
<p><b>ABSTRACT</b><br>
Previous studies have shown the high levels of noise in a hospital environment caused by many factors such as traffic noise, and the ensuing implications on sleep quality of hospitalized patient’s especially in ICU’s. This study was undertaken to measure noise levels in a pulmonary ward and an ICU and to detect the influence of the environmental factors on patients’ sleep quality as well as lack of rest in the day, during their hospitalization. Measurements were undertaken using the Cirrus CR:245/R2 Environmental Noise Analyzer, for a period of two weeks, both in a 30-bedded pulmonary ward and in a 16 bedded general ICU. Sleep quality, sleep during the day and the effect of various environmental factors’ on them were surveyed on 74 hospitalized patients by means of a questionnaire. Generally, noise levels in the ward were significantly lower than those in the ICU (52.6 dB(A) vs. 59 dB(A)). Noise levels in the ward decreased significantly in the course of the day, which was not the case in the ICU. Patients’ perception of sleep quality in the hospital was worse than at home, especially during the first night, with little sleep during the day. Environmental factors did not significantly influence patients’ sleep quality. Noise levels in the ward are high in general, reaching levels close to those of an ICU. Even with the given decrease in the recorded noise, levels remain above the accepted values. Patients’ quality of sleep is poorer than home, yet they do not report annoyance by any environmental factor.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p639.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p443" class="affilation"></a>Influence of Traffic Sound Parameters on the Reading Performance in Elementary School Children</h2>
<h3>Helga Sukowski, August Schick</h3>
<p class="affilation">Institute of Psychology, University of Oldenburg, 26111 Oldenburg, Germany</p>
<p><b>ABSTRACT</b><br>
Reading is an important and frequent activity in the daily life of school children. In addition to personal factors, reading development and reading skills can also be influenced by external factors, like e.g. environmental noise caused by airplanes, cars or trains. The question in the current study was, whether variations of the sound parameters “spectral shape” and “traffic density” in moderate road traffic sounds have an influence on the reading performance in elementary school children. The results show that a variation of a few isolated sound parameters can have an acute effect on reading performance even for moderate traffic noise. Despite of the small statistical significance achieved so far, further research in this field will be valuable, since the exposure to traffic noise is still increasing in our environment. In future research more variations along the chosen dimensions (spectral shape, realized by a filter procedure; traffic density) and also other sound parameters like loudness, tonal and temporal character should be investigated.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p443.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p604" class="affilation"></a>Vibration from Railways: Can we Achieve Better Than ±10 dB Prediction Accuracy?</h2>
<h3>Hugh Hunt (1), Mohammed Hussein (2)</h3>
<p class="affilation">(1) Cambridge University Engineering Department, Cambridge, CB2 1PZ, UK (2) School of Civil Engineering, University of Nottingham, Nottingham, NG7 2RD, UK</p>
<p><b>ABSTRACT</b><br>
This paper examines the sources of uncertainly in models used to predict vibration from underground railways. It will become clear from this presentation that by varying parameters by a small amount, consistent with uncertainties in measured data, the predicted vibration levels vary significantly, often by more than 10 dB. This error cannot be forecast. Small changes made to soil parameters (Compressive and Shear Wave velocities and density), to slab bending stiffness and mass and to the measurement position give rise to changes in vibration levels of more than 10 dB. So if 10 dB prediction error results from small uncertainties in soil parameters and measurement position it cannot be sensible to rely on prediction models for accuracy better than 10 dB. The presentation will demonstrate in real time the use of the new - and freely-available - PiP software for calculating vibration from railway tunnels in real time.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p604.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p578" class="affilation"></a>Environmental Effects from Vibration Emitted from the Operation of Urban Highways: A Measurement Campaign at Athens Ring Motorway Network</h2>
<h3>Konstantinos Vogiatzis</h3>
<p class="affilation">Faculty of Civil Engineering, Transportation Department, University of Thessally, Pedion Areos - 383 23 Volos Greece</p>
<p><b>ABSTRACT</b><br>
In order to record and evaluate the vibration and ground noise levels emitted from road traffic during operation of “Attiki Odos” (Athens Ring Motorway) in the most unfavourable road section (as far as the traffic flows and the near by sensitive urban environment is concerned), a full monitoring program [1] was executed regarding the recording and evaluation of the vibration velocity at the nearest to the road edge residence buildings in 5 representative locations along the network. The selection of these locations was made in accordance to the prevailing land use conditions the relevant “hard” and “soft” soil conditions, and the distance from the road edge, so that the most unfavourable conditions of vibration velocity diffusion were ensured, based on the road system’s operation data.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p578.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p579" class="affilation"></a>Occupational Noise Vibration & Air Pollutants Fluctuation Inside the Toll Booths in the Athens Ring Motorway Network: “Attiki Odos”</h2>
<h3>Konstantinos Vogiatzis, Nikolaos Eliou</h3>
<p class="affilation">Faculty of Civil Engineering, Transportation Department, University of Thessaly, Pedion Areos - 383 23 Volos Greece</p>
<p><b>ABSTRACT</b><br>
Attikes Diadromes S.A (a company ensuring the “Maintenance - Operation and Exploitation of the motorway Elefsina - Stavros - Spata Airport & West Peripheral Ymittos Avenue ”), in close cooperation with the University of Thessaly -Faculty of Civil Engineering (Transportation sector) has executed during 2006 an extended specialised research program, in, both, selected toll booths of “Attiki Odos” network (Athens Ring Road) & also selected machinery equipment, aiming at the detection of both occupational & vibration noise levels possible as long as harmful chemical factors generated from the road circulation in the relevant selected toll booths of Attiki Odos, aiming at the evaluation of the relevant impact at the employees of both toll facilities & machinery equipment use are exposed during working periods.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p579.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p638" class="affilation"></a>Environmental Noise Investigation Procedure in the Urban Road Network in Malta</h2>
<h3>Konstantinos Vogiatzis (1), Vasilis Vasiliadis (2)</h3>
<p class="affilation">(1) University of Thessaly Faculty of Civil Engineering, 38334 Volos Greece (2) Aristotle University of Thessaloniki, School of Technology, Laboratory of Architectural, Technology, 54126 Thessaloniki Greece</p>
<p><b>ABSTRACT</b><br>
The purpose of the project is the implementation of the Noise Regulations and the setting up of procedures to be followed in conjunction with said Noise Regulations Environmental noise. Environmental noise seriously harms the quality of life and road traffic noise and neighborhood noise are the most common causes of complaints in Malta. Over a long period of time, noise has a determinable influence on well-being and perceived quality of life. Sleep disturbance from noise may possibly affect public health. With local councils already making their complaints, sources need to be identified and noise limits set out in proper regulations. In Malta, there have never been specific noise levels that could be used during investigations, and thus it has always been a problem how such complaints from the general public could be investigated. At present, complaints regarding ‘noise pollution’ are referred to the Police who may take action against offenders if they cause ‘nuisance to neighbours’. However this method is not efficient. The expected results of this project were effective public health regulations for the control of residential noise and proficiency in residential noise investigations and monitoring. Trained health inspectors able to effectively and professionally apply investigations procedures and make use of the appropriate noise monitoring equipment. A very important and effective tool for the Malta Authorities was the project deliverable “Draft Legislation on Noise Pollution Limits Measurement & Control for Various Land Uses” which includes a)Main Definitions b)Noise Sources & Affected Receptors (Premises & Land Uses) c)Noise Limits and Indices d)Measurement methods & Correction factors e)Suggestions for Procedures & Penalties f)Measurement test report.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p638.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p481" class="affilation"></a>The PiP Model, a Software Application for Calculating Vibration from Undergrond Railways</h2>
<h3>Mohammed Hussein (1), Hugh Hunt (2)</h3>
<p class="affilation">(1) School of Civil Engineering, University of Nottingham, Coates Building, University Park, Nottingham, NG7 2RD, UK (2) Engineering Department, University of Cambridge, Trumpington Street, Cambridge, CB2 1PZ, UK</p>
<p><b>ABSTRACT</b><br>
Significant vibration in buildings near underground tunnels is attributed to moving trains. Vibration is generated due to irregularities of wheels and tracks and propagates to nearby buildings causing annoyance to people and malfunctioning of sensitive equipment. Modelling of vibration from underground railways is gaining more interest on account of the need for quick tools to design vibration countermeasures for both existing and newly constructed tunnels. This paper describes a software application for calculating vibration from underground railways, called the Pipe-in-Pipe (PiP) model. The software has a user-friendly interface and is available on the internet as a freeware for engineers in charge of designing of vibration countermeasures in railway tunnels. The PiP model accounts for a train running on a floating-slab track in a tunnel embedded in the ground. The software calculates the Power Spectral Density (PSD) of the vertical displacement at any selected point in the soil for a roughness excitation of a unit value (i.e. white noise). It also calculates the Insertion Gain (IG) which is the difference in decibel between the displacement PSD after and before changing parameters of the track, tunnel or soil. The latest version of the software plots the displacement contours around the tunnel and accounts for a bedrock layer below the tunnel using the mirror-image method. The software is computationally efficient as it calculates results accurately and quickly on a personal computer unlike other available models of vibration from underground railways which take much longer time and require huge computational resources. A full description of the current version of the software is given in this paper along with ongoing developments that will appear in future versions.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p481.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p544" class="affilation"></a>Modelling of Floating-Slab Tracks with Discontinuous Slabs in Underground Railway Tunnels</h2>
<h3>Mohammed Hussein (1), Hugh Hunt (2)</h3>
<p class="affilation">(1) School of Civil Engineering, University of Nottingham, Coates Building, University Park, Nottingham, NG7 2RD, UK (2) Engineering Department, University of Cambridge, Trumpington Street, Cambridge, CB2 1PZ, UK</p>
<p><b>ABSTRACT</b><br>
Floating-slab tracks are known as effective means for isolating vibration from underground railway tunnels. Slabs are supported on tunnels via rubber bearings or steel springs. The slab can be continuous or discontinuous. Continuous slab is cast in-situ and discontinuous slab is constructed in discrete pre-cast sections. A track with discontinuous slab exhibits more resonances due to constructive interference of waves that reflect at both ends of the slab. This paper presents a new method for modelling floating-slab tracks with discontinuous slabs in underground railway tunnels. The track is subjected to a harmonic moving load. The model consists of two sub-models. The first is an infinite track with periodic double-beam unit formulated as a periodic infinite structure. The second is modelled with a new version of the Pipe-in-Pipe (PiP) model that accounts for a tunnel wall embedded in a half-space. The two sub-models are coupled by writing the force transmitted from the track to the tunnel as a continuous function using Fourier series representation and satisfying the displacement compatibility. The displacements at the free surface are calculated for a track with discontinuous slab and compared with those of a track with continuous slab. The results confirm that the far-field vibration can significantly be increased due to resonance frequencies of slab for tracks with discontinuous slabs.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p544.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p713" class="affilation"></a>Free Vibration of Vertical Pump</h2>
<h3>Chun Hee Bae, Yeon Whan Kim, Hun Lee, Cheul Whan Cho</h3>
<p class="affilation">Korea Electric Power Research Institute, 130-16,Munji-Dong, Yousung-Gu, Daejeon, Korea</p>
<p><b>ABSTRACT</b><br>
Vertical pumps are widely used owing to the fact that they occupy small floor space. In this type of pumps, however, the vibration problems are very important, since in many cases, they have less stiffness in comparison with later pumps. This study presents a simple solution method for calculating the natural frequencies and modes of vertical pumps. In this study, a model of a vertical pump was developed and the no dimensional parameters for the vibration characteristics of it were determined. Added mass was calculated for the effects of water and the transfer matrix method was used. Also the result of the calculation was demonstrated by the practical test of power plant vertical pump.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p713.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p823" class="affilation"></a>Eigenvalue Variation of Fuel Rod Exposed to Uniform Axial Flow</h2>
<h3>Nam-Gyu Park, Joon-Kyu Park, Jung-Min Suh, Kyu-Tae Kim</h3>
<p class="affilation">R&D Center, Nuclear Fuel Technology Office, Korea Nuclear Fuel Co., LTD., 493, Deokjin-dong, Yuseong-gu, Daejeon, Korea</p>
<p><b>ABSTRACT</b><br>
Flow-induced vibration usually causes fretting wear in fuel rods during reactor operation, thus a prior knowledge on dynamics of fuel rod exposed to the flow condition should be provided. This work shows that dynamic characteristics of fuel rod depend on axial flow velocity. Assuming small lateral displacement, the effects of uniform axial flow are investigated. The results also show that axial flow generally reduces fuel rod stiffness and raises its damping in the normal condition. Solving generalized eigenvalue equation of the fuel rod system, the critical axial velocities at which the motion becomes unstable were found. Based on the simulation results, on the other hand, it turns out that the coolant flow in nuclear reactors rarely affect to the stability of nuclear fuel rod even in the severe condition.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p823.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p412" class="affilation"></a>Using Statistical Methods to Predict Induced Sound and Vibration in Aerospace and Automotive Applications</h2>
<h3>Patrik Ragnarsson (1), Christophe Schram (1), Michel Tournour (1), David Freed (2), Sivapalan Senthooran (2), Fongloon Pan (2)</h3>
<p class="affilation">(1) LMS International, Interleuvenlaan 68, 3001 Leuven, Belgium (2) Exa Corporation, 150 North Hill Drive, Suite 2, Brisbane, CA, USA</p>
<p><b>ABSTRACT</b><br>
Wind induced sound and vibrations are areas where a lot of research efforts are spent today. Due to the random nature of turbulent flow fields, a deterministic approach to the problem will just describe one of many possible solutions. To reduce statistical uncertainty and achieve a robust solution of a problem a large number of calculations can be performed (i.e. Monte Carlo simulations). The focus of this paper is on a method to simplify the calculations involved in using such stochastic approaches. The experimental and numerical test case consists of a plate-backed cavity where the rectangular plate is excited by a reattaching turbulent boundary layer, and is supported by a visco-elastic seal. The approach is based on a Power Spectral Density (PSD) loading using a Corcos model. The statistical parameters are calculated by processing deterministic flow data. These data consist of time-series wall pressure fluctuations (WPF) obtained by CFD simulations. The WPF time series were computed using Exa’s PowerFLOW CFD software, whereas the Vibro-acoustic responses were computed using LMS Virtual.Lab and Sysnoise. The agreement between the random acoustic method using the Corcos model and a normal deterministic method is quite good. The over all levels are similar, and the results from the deterministic calculation show, as expected, more fluctuations than the random acoustic results. The random acoustic method is in a sense a superposition of a large number of deterministic load cases, hence the more smooth and averaged curve.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p412.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p566" class="affilation"></a>Transient Dynamic Responses of an Internal Liquid-LNG Tank-Sea Water Interaction System Excited by Waves and Earthquake Loads</h2>
<h3>Y. P. Xiong, J. T. Xing, M. Tan</h3>
<p class="affilation">School of Engineering Sciences, Ship Science, University of Southampton, Southampton, SO17 1BJ, UK</p>
<p><b>ABSTRACT</b><br>
Sloshing problems in partially filled large LNG carriers are of increasing concern because sloshing loads may endanger LNG carriers in operations. Currently, most investigations on sloshing problems mainly focus on the analysis of liquids in rigid tanks which omitted fluid-structure interactions. Based on a mixed displacement-pressure finite element method developed, the authors recently investigated the natural vibration of an internal liquid-elastic structure-external water interaction system. The simulation demonstrated the significance of the interactions between internal liquid sloshing modes and floating modes of LNG tanks on the external sea water. This paper further studies the dynamic responses of this integrated system subject to sea waves and earthquake excitations. The sea wave loads are modelled by pressure waves with different frequencies applied to a boundary of the external water domain and the ground motion data recorded from El-Centro earthquake is used as an earthquake load to the system. The numerical analysis on the dynamic responses of this coupled system further confirms the necessity to consider fluid-structure interactions for safe LNG ship designs.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p566.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p543" class="affilation"></a>Dissemination of Predicted Noise Levels in a 3D Visualised Interactive Environment Through the Internet for 3D EIA and Planning Projects (Hong Kong)</h2>
<h3>Andy W. L. Chung (1), W. M. To (2), James P. S. Choi (1)</h3>
<p class="affilation">(1) EDMS (Hong Kong) Limited, 1009, World Wide House, 19 Des Voeux Road Central, Hong Kong SAR (2) Macao Polytechnic Institute, Rua de Luis Gonzaga Gomes, Macao SAR</p>
<p><b>ABSTRACT</b><br>
It is a global trend that public demands for environmental noise information from the Authority on where they live, where they work or places of interest. Predicted noise data presented in the form of noise maps, 3-Dimensional (3D) photo-realistic model and virtual reality have become more and more popular. However, such models usually present only the noise levels predicted for the worst-case scenario. In other words, changes in noise levels over time with varying traffic conditions are not shown. There is thus a demand for temporal, i.e. time-varying, noise data presentation. This paper presents the results of a demonstration project where time-dynamic noise levels can be visualised while a viewer navigates a 3D model. Also, a brief introduction of the key features of a web-based platform specifically designed for disseminating multi-project time-varying 3D models to engage stakeholders in informed discussions on major proposals and facilitating a better understanding of road projects and issues in Hong Kong through the use of 3D electronic visualisation tools is provided.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p543.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p79" class="affilation"></a>How Territory-Wide GIS-Based Road Traffic Noise Assessment Tools Facilitate Decision Making in Strategic Level Environmental Assessment</h2>
<h3>C. K. Lee, C. W. Law, Aaron S. W. Lui, Maurice K. L. Yeung</h3>
<p class="affilation">Environmental Protection Department, The Government of the Hong Kong Special Administrative Region of the People’s Republic of China, 26th Floor Southorn Centre, Wanhcai, Hong Kong</p>
<p><b>ABSTRACT</b><br>
Strategic environmental assessment (SEA) is a systematic process, with multi-stakeholder involvement, for analysing and evaluating environmental implications of proposed policies, plans and programmes (PPP), for assisting in strategic or planning decision-making; and for following up strategic or planning decisions. SEA has been widely adopted in many countries as a tool to facilitate the integration of environmental considerations into the PPP formulation processes and to facilitate the achievement of long term sustainability. Some SEA examples in Hong Kong are the Territorial Development Strategy Review, Comprehensive Transport Studies, Port Developments, and Hong Kong 2030: Planning Vision and Strategy. They are critical in developing long term strategies for the development of Hong Kong as an international city. Among various considerations, road traffic noise is one of the key environmental indicators to be evaluated in the SEA of PPP. In the early 90s, road traffic noise in SEA was either assessed in a qualitative approach or was carried out by making reference statistically to the assessment of some representative locations. A systematic and quantitative comprehensive noise assessment tool to evaluate the various scenarios based on the various proposed PPP was not available at that time. With the latest Geographic Information System (GIS) technology and large-scale noise computer modelling, a GIS-based noise model for SEA was developed to provide a systematic and quantitative tool to evaluate the noise impacts of various proposed PPP for decision making. This paper briefly explains the GIS-based noise model and its application in recent SEAs, which assists the policy makers or the public to comprehend traffic noise impacts of various scenarios precisely and continuously at the early stages of planning and facilitate making the decision.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p79.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p78" class="affilation"></a>Practical Experience in Engaging the Public Through Interactive 3D Technology in Retrofitting Barrier Projects on Existing Roads</h2>
<h3>C. W. Law, C. K. Lee, Aaron S. W. Lui, Maurice K. L. Yeung</h3>
<p class="affilation">Environmental Protection Department, The Government of the Hong Kong Special Administrative Region of the People’s Republic of China, 26th Floor Southorn Centre, Wanhcai, Hong Kong</p>
<p><b>ABSTRACT</b><br>
Public engagement is an important element that is critical to the planning and success in retrofitting barriers on existing roads. Residents living close to the area, where retrofit barriers are proposed to be installed, may have strong views as to whether barriers should be erected or not. To communicate effectively with the public and to enhance public involvement during the planning stage, it is essential that the noise information presented should be as simple and as easy to understand as possible. Traditional presentation approaches using tables and maps are often not easily understood by the public or even professionals such as environmental consultants and engineers, especially for a project in a complex high-rise city like Hong Kong. This paper describes the practical experience of the Environmental Protection Department (EPD) of the Government of the Hong Kong Special Administrative Region using three-dimensional (3D) visualization tool to engage the public for their views of retrofitting barrier projects in Hong Kong. The tool provides a 3D interactive virtual reality (VR) environment, for the public to walk and fly through the future 3D space to visualize the proposed retrofitting barriers and to grasp the predicted noise information attached with it. This helps the public, the local district councilors and the decision makers to make their choices. The tool is developed by using Geographic Information System (GIS), 3D digital model technology and large-scale noise model application for noise prediction and assessment. An application of web-based data dissemination is also discussed.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p78.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p794" class="affilation"></a>Technology Driven Solutions for the Quantification of Urban Road Noise</h2>
<h3>Christopher Hoar (1), Jonathan Pyke (2), Hartmut Stapelfeldt (3), Simon Shilton (4)</h3>
<p class="affilation">(1) NGIS China Limited, 19a Time Centre, 53-55 Hollywood Road Central, Hong Kong, PRC (2) Innnovation Environment Limited, 11a West Wing, Sincere Insurance Building, 6 Hennessy Road, Wanchai, Hong Kong, PRC (3) Stapelfeldt Ingenieurgesellschaft mbH, Wilhelm-Brand-Str. 7, D - 44141 Dortmund, Germany (4) iSONIQ limited, Trident One, Styal Road, Manchester, M22 5XB, United Kingdom</p>
<p><b>ABSTRACT</b><br>
Road noise is widespread in urban and suburban Asia and commonly the predominant source of ambient noise during both daytime and night-time. Prolonged excessive exposure to road noise can cause adverse effects on health and well being through sleep disturbance and stress. The challenge to government agencies throughout the region to predict and quantify noise exposure to populations has led to a number of noise prediction and mapping initiatives. These typically aim to express noise exposure problems in terms that can be compared with existing and emerging guidelines that seek to address acute and adverse noise-related social impacts. Understanding the potential problems facilitates informed decision making in development and political promotion of strategies for reducing noise and promoting sustainable urban living. This is highly pertinent to the Asian nations whom promote the successive regeneration of the urban environment and, as economies prosper, the development of sustainable new towns to accommodate population growth. Computerised noise exposure prediction technology is now widely accepted as an effective way to help quantify noise exposure to support decision-making on transport policy, development density and at source noise control measures. Most European Union member states, Canada, USA, developed Asian nations and Australia already have programs in place utilising such systems for the staged process of reducing noise exposure in large cities and suburban areas. Recently, improved system integration technologies have allowed organisations to make noise mapping tools more widely available, allowing use of these systems by both generalists and specialists alike. The technology offers enhanced interaction and offers a transparency to a highly technical process, which promotes a greater level of stakeholder participation. This paper discusses noise mapping progress and provides an introduction to the types of technologies being employed as well as suggestions on the ground-truthing of technical models.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p794.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p54" class="affilation"></a>State-Wide Road Noise Mapping of Queensland, Australia</h2>
<h3>Daniel Naish</h3>
<p class="affilation">Planning, Design and Operations Division, Department of Main Roads, Queensland Government, 477 Boundary Street, Spring Hill, Brisbane, Queensland, Australia</p>
<p><b>ABSTRACT</b><br>
The Queensland Department of Main Roads (Main Roads) has recently undertaken a State-wide road traffic noise mapping project which relied upon GIS information. The purpose of the mapping was primarily for purposes of planning Main Roads road traffic noise management program. The mapping used the relatively simple algorithms of the United Kingdom, Calculation of Road Traffic Noise model (CoRTN). CoRTN is known to provide satisfactory results for assessment purposes close to roads but is not computationally intensive. The results of the information obtained from the mapping provided an indication of the level of road traffic noise exposure for the population of Queensland. GIS data, such as the Digital Cadastral Database (DCDB), the State controlled Road Network with CoRTN attributes, planning scheme data (urban, commercial, and rural) were loaded into the SoundPLAN software using its GIS interface module. Road traffic noise calculations were performed for each local government area in Queensland, and then grouped into each of Main Roads Districts. The various results of the project are discussed and finally future improvements for the state-wide mapping project are made.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p54.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p658" class="affilation"></a>GIS for the Evaluation of Road Traffic Noise at Areas Facing Roads in Japan - Key Functions Including Estimation of the Numbers of Residents in Buildings</h2>
<h3>Hiroyuki Imaizumi (1), Kazutoshi Fujimoto (2), Yasumori Takahashi (1), Ken Anai (2), Yasuhiro Hiraguri (2)</h3>
<p class="affilation">(1) National Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan (2) Faculty of Human-Environment Studies, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581 Japan</p>
<p><b>ABSTRACT</b><br>
GIS is an effective tool to accumulate various kinds of numerical maps and the attribute data relating to road traffic noise and to analyze the correlations between the data. In addition, combining prediction method of the road traffic noise with the benefits of GIS allows us to evaluate the noise field, from the past to the future, at areas facing roads concerned. Since propagation of road traffic noise is remarkably affected by buildings or other obstacles along the roads, their physical properties such as the locations and the heights should be carefully taken into account to calculate the road traffic noise. For evaluation of noise exposure by road traffic, it is important to distinguish between residential and non-residential buildings along the roads and then estimate the number of residents in each building. However, reasonable method to assign the population to the residential buildings, especially to the condominiums, is still a problem to be solved, because of limitations of information involved in the relating databases. The authors have shown a basic idea for calculating the number of people in the residential buildings and have been developing the method, in which the building maps and the population by the national census are used on GIS. In this paper, we discuss some key functions on the GIS application, including assignment of the residents, which are essential to be widely used for management and assessment of the road traffic noise.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p658.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p799" class="affilation"></a>Standardization of Road Traffic Noise Map in Korea</h2>
<h3>In-Sun Park (1), Sang-Kyu Park (1), Daejoon Kang (2)</h3>
<p class="affilation">(1) Department of Environmental Engineering, Yonsei University Wonju Campus, Wonju, Gangwon, 220-710, Korea (2) National Institute of Environmental Research, Kyungserdong Sergu, Inchun 404-708, South Korea</p>
<p><b>ABSTRACT</b><br>
Since study on noise map in Korea has begun in the late 1990, focus was on how to use interpolation methods of Arc GIS to compare the measured noise data with predicted result. However, use of professional noise map has been very rare because basic data such as information of roads, traffic flows and geography are not enough. In this study, noise maps of a city in Korea have been made using commercial noise map software by measuring the basic data in the city. This result will be used to evaluate the environmental impact of noise from various noise sources and to implement the Korean noise map standard.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p799.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p396" class="affilation"></a>Noise Mapping - What for and How to be More Effective?</h2>
<h3>Kin-che Lam</h3>
<p class="affilation">Department of Geography and Resource Management, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong</p>
<p><b>ABSTRACT</b><br>
In the last decade, noise mapping has been applied to an increasing number of cities in different parts of the world utilizing recent advancement in noise prediction and GIS technologies. This paper reviews the noise mapping projects that have been undertaken and examines the extent to which the stated objectives have been achieved, technical problems overcome and how they can become more effective in facilitating public participation, project planning and formulation of noise action plans and policies. It has been observed that some noise mapping projects are data-rich but information-poor. To address current urban noise problems, the paper suggests that future noise mapping exercises should be focused on human responses and policy-oriented. The noise mapping tools should also be adapted for strategic planning and assessment. Current practices should be enhanced to make noise mapping a useful informational tool, an interactive planning tool as well as an effective policy assessment instrument.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p396.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p676" class="affilation"></a>An Overview of the Impact of Source Data Accuracy Variations on the Overall Accuracy of Noise Maps</h2>
<h3>Peter Hepworth</h3>
<p class="affilation">Hepworth Acoustics Limited, 5 Bankside, Crosfield Street, Warrington, WA1 1UP, UK</p>
<p><b>ABSTRACT</b><br>
The paper will provide an overview of research carried out by Hepworth Acoustics Ltd and others on the impact on the overall accuracy of noise maps from variations in the level of accuracy of individual data items. Noise mapping carried out for the European Union Environmental Noise Directive (END) will be used to inform the general public across Europe of the current distribution of noise levels in urban areas and adjacent to main transport noise sources, as well as being used to identify hot spots for future mitigation measures. In order for the general public to maintain confidence in the process, there is a need to be able to explain the level of accuracy of the maps produced, in order to manage public expectations. To be able to explain the level of accuracy, the noise mapping practitioners need to be able to detail the overall level of accuracy of the noise map, and to be able to understand the implications on overall accuracy of using imperfect data for some or all data requirements. This paper reports on a range of work carried out for the Department of Environment, Food and Rural Affairs (Defra) in the United Kingdom that has looked at accuracy implications of variations in source data accuracy. The paper will also discuss whether the type of noise source being modelled affects the accuracy requirements for source data.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p676.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p764" class="affilation"></a>Buckling and Vibration Analysis of Magnetoelectroelastic Beam</h2>
<h3>A. Kumaravel, N. Ganesan, Raju Sethuraman</h3>
<p class="affilation">Machine Design Section, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600 036, India</p>
<p><b>ABSTRACT</b><br>
In this paper, linear buckling and vibration behaviour of multiphase magnetoelectroelastic (MEE) cantilever beam is analysed using finite element approach. The constitutive equations for the magnetoelectroelastic materials are used to derive finite element equations involving the mechanical, electrical and magnetic fields for the structure. The multiphase magnetoelectroelastic beam consists of piezomagnetic (CoFe<sub>2</sub>O<sub>4</sub>) matrix reinforced by piezoelectric (BaTiO<sub>3</sub>) material for different volume fraction. The influences of material constants on critical buckling load were studied. Numerical study on multiphase magnetoelectroelastic beam with different volume fraction was attempted.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p764.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p243" class="affilation"></a>Linear Modelling of Magneto-Rheological Dampers Using Hybrid Intelligence Technique</h2>
<h3>Haiping Du, Nong Zhang</h3>
<p class="affilation">Mechatronics and Intelligent Systems, Faculty of Engineering, University of Technology, Sydney, PO Box 123, Broadway, NSW 2007, Australia</p>
<p><b>ABSTRACT</b><br>
In this paper, the local linear models of a magneto-rheological (MR) damper are obtained based on the Takagi-Sugeno (T-S) fuzzy modelling approach. In these local linear models, the output force of the MR damper is expressed as the linear summation of the state variables (relative displacement and relative velocity) and input voltage. To obtain these local linear models with high accuracy, the genetic algorithm (GA) with a new encoding method is applied to search for the optimal model parameters. The proposed hybrid intelligence technique can evolve the fuzzy rule structure (number of rules and selection of rules) and the input structure (number of premise inputs and selection of premise inputs) simultaneously so that the obtained linear models have the simplest structures without decreasing the modelling accuracy. To validate the proposed approach, the modelling errors between the MR damper output and the corresponding linear model output are compared for the given number of rules case and for the automatically selected rules case with using three different selection approaches for the premise input variables. It is confirmed by the validation results that the proposed hybrid intelligence technique can find the optimal linear model for the MR damper.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p243.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p694" class="affilation"></a>Design of Semi-Active Tuned Mass Damper for Controlling Seismically Induced Responses of Elastic and Inelastic Structures</h2>
<h3>Sang-Hyun Lee, Sung-Sik Woo, Seung-Ho Cho, Lan Chung</h3>
<p class="affilation">Department of Architectural Engineering, Dankook University, Seoul, Korea</p>
<p><b>ABSTRACT</b><br>
In this study, the performance of a passive tuned mass damper (TMD) and a semi-active TMD (STMD) was evaluated in terms of seismic response control of elastic and inelastic structures under seismic loads. First, elastic displacement spectra were obtained for the damped structures with a passive TMD and with a STMD proposed in this study. The displacement spectra confirm that STMD provides much better control performance than passive TMD in spite of having less stroke. Also, the robustness of the TMD was evaluated by off-tuning the frequency of the TMD to that of the structure. Finally, numerical analyses were conducted for an inelastic structure of which hysteresis was described by Bouc-Wen model and the results indicated that the performance of the passive TMD of which design parameters were optimized for a elastic structure considerably deteriorated when the hysteretic portion of the structural responses increased, while the STMD showed about 15-40% more response reduction than the TMD.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p694.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p708" class="affilation"></a>Localisation of Coherent Sound Sources Using a Microphone Array</h2>
<h3>Chaoying Bao (1), Hayden Albrey (2), Jie Pan (2)</h3>
<p class="affilation">(1) Building A51, DSTO WA, PO Box 2188, Rockingham, WA 6958, Australia (2) School of Mechanical Engineering, University of Western Australia, Crawley, WA 6009, Australia</p>
<p><b>ABSTRACT</b><br>
Beamforming of a sound field using microphone arrays forms a foundation of acoustic camera technology, which overlays a sound pressure map (acoustic image) with an image of sound sources (visual image) to provide quick source localisation. Recent experiments conducted at the University of Western Australia on the measurement of sound radiation using an acoustic camera have observed significant shifts of the acoustic image from the visual image when the different parts of the sound source are coherent. In this paper, we examine the reason behind this image shifting phenomenon and present an approach that uses adaptive beamforming together with a spatial smoothing technique to eliminate those shifts. Sound radiations from loudspeakers and a music flute measured by the acoustic camera are used to illustrate the effectiveness of the approach.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p708.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p571" class="affilation"></a>Loud: A 1020-Node Microphone Array and Acoustic Beamformer</h2>
<h3>Eugene Weinstein (1), Kenneth Steele (2), Anant Agarwal (2,3), James Glass (3)</h3>
<p class="affilation">(1) Courant Institute of Mathematical Sciences, 251 Mercer Street, New York, NY 10012, USA (2) Tilera Corporation, 1900 West Park Drive, Suite 290, Westborough, MA 01581, USA (3) MIT Computer Science and Artificial Intelligence Laboratory, 32 Vassar Street, Cambridge, MA 02139, USA</p>
<p><b>ABSTRACT</b><br>
Recording speech and other sound is difficult in environments with a large amount of noise and/or crosstalk. In these environments, array microphones are needed in order to obtain a clean recording of desired speech. In this work, we have designed, implemented, and tested LOUD, a 1020-node microphone array. To the best of our knowledge and as documented by Guinness World Records [6], this is currently the largest microphone array in the world. We have implemented an acoustic beamforming algorithm for sound source amplification in a noisy environment, and have obtained preliminary results demonstrating the efficacy of the array. From one to 1020 microphones, we have shown a 13.7 dB increase in peak SNR for a representative utterance, an 87.2% drop in word error rate (WER) with interferer present, and an 91.3% drop in WER without an interferer.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p571.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p802" class="affilation"></a>An Investigation into the Fault Detection of Machines Based on Acoustic Array Systems</h2>
<h3>J. Jiang (1), F. Gu (1), D. J. Moore (1), A. D. Ball (1), K. Liu (2)</h3>
<p class="affilation">(1) School of Mechanical Aerospace and Civil Engineering, University of Manchester, Manchester, M60 1QD, UK (2) Institute of Acoustics, Chinese Academy of Sciences, 21 Bei Si Huan Xi Lu, Beijing 100080, PRC</p>
<p><b>ABSTRACT</b><br>
Acoustic condition monitoring (CM) has a number of significant merits such as remote measurement and rich information content. In recent years it has been gaining increasing attention because of the rapid development in sensing and processing methods for interference noise suppression and demands for accurate CM. In this paper, a new acoustic detection scheme is investigated based on array technology. The scheme uses only a small number of microphones (about 5), which is easy and realistic to implement in CM, compared with conventional array applications. The capabilities of different small array configurations are studied theoretically in terms of detection accuracy and potential diagnosis capabilities. Numerical simulations have shown that a 5-sensor tetrahedron array produces high accuracy for source identification and fault detection. Based on this array configuration, an acoustic CM system is developed and embedded with array technologies, advanced signal processing and pattern recognition. Experimental results show that this system has a great potential in detecting machine faults in an industrial environment.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p802.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p515" class="affilation"></a>One Sensor Microphone Array Application in Source Localization</h2>
<h3>Percy F. Wang (1), Mingsian R. Bai (2)</h3>
<p class="affilation">(1) Southern Research Institute/University of Alabama at Birmingham, Birmingham, Alabama, USA (2) Department of Mechanical Engineering, National Chiao-Tung University, Hsin-Chu, Taiwan</p>
<p><b>ABSTRACT</b><br>
The conventional digital signal processing dictates that a signal must be sampled at Nyquist rate or higher (over-sampling) in order to be represented without error. For multi-channel microphone arrays, it calls for the same bandwidth for each of the channels. Not only good sensors are needed, but many channels of A/D converters are required. This is wasteful of sensing and data acquisition resources. Over the past years, a new theory of Compressive Sensing Processing (CSP) has begun to emerge, in which the signal is sampled and compressed simultaneously at a greatly reduced rate. Exciting new theory and applications are popping up in analog-to-digital conversion, image processing and other areas. This paper will explore the theoretical foundations and emerging applications of Compressive Sensing. We are especially interested in low cost, high channel-count applications in acoustic applications. In this paper, an innovative design is proposed for noise source identification. The hardware required is a single microphone sensor that utilizes mechanical multi-gate array with deterministic or random opening sequences. The analog to digital conversion is accomplished by a high speed single-channel A/D converter. Since only one sensor and one A/D channel are needed, the electronic circuit and hence the associated cost can be reduced. The computational results are checked with known sources to make sure the algorithm is working.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p515.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p661" class="affilation"></a>Optimal Circular Array Configuration</h2>
<h3>S. K. Lau</h3>
<p class="affilation">Department of Building Services Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong</p>
<p><b>ABSTRACT</b><br>
Beamforming based microphone arrays have been prove to be useful for sound source localization. It has advantage of tracking the sources in time, space and frequency domains, simultaneously. In general, the performance of beamformer will be various in terms of the beamwidth and Maximum Sidelobe Level (MSL), as a result of the configuration of the linear planar and 3-dimension arrays. Though spatial filter can adjust the beamwidth, but it is a trade off of the maximum sidelobe level. Previous works assessed the performance of microphone array with linear and specified array geometry. Multi-arm spiral and linear array location schemes have been adopted for planar array in previous studies. They are based on the combinations of circular arrays with different radii of circles and angular distances between the reference microphones of circles. Higher performance can be observed for non-redundancy array configuration, where there is no repeated vector spacing between sensors (i.e. co-array). However, the performance of the optimal multi-circular array has not yet been examined in details. The co-array pattern is indirectly controlled. The present study investigates the performance of multi-circular array. Main lobe area and the ratio of main & maximum sidelobe are investigated. Design of microphone arrays based on the optimal radii and angular distances is proposed in the present study. The results show that microphone array configuration based on the present approach has better performance on the mapping of the sound field. Design of three-circular array with seven microphone on each circle is developed.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p661.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p534" class="affilation"></a>Using the Hybrid FE-SEA Method to Predict Structure-Borne Noise Transmission in a Trimmed Automotive Vehicle</h2>
<h3>A. Charpentier (1), V. Cotoni (1), K. Fukui (2)</h3>
<p class="affilation">(1) ESI Group, 12555 High Bluff drive, San Diego 92130 - USA (2) Nissan Motor Co. 1-1, Morinosatoaoyama, Atsugi-shi Kanagawa, 243-0123 - Japan</p>
<p><b>ABSTRACT</b><br>
A Hybrid method that rigorously couples Statistical Energy Analysis (SEA) and Finite Element Analysis (FEA) has been used to predict interior noise levels in a trimmed vehicle due to broadband structure-borne excitation from 200Hz to 1000Hz. This paper illustrates how the Hybrid FE-SEA technique was applied to successfully predict the car response by partitioning the body-in-white into stiff components described with FE and modally dense components described with SEA. Additionally, it is demonstrated how detailed local FE models can be used to improve SEA descriptions of car panels and couplings. The vibration response of the bare car floor and dash is validated against experiments. Next, the radiation efficiency and vibration response of bare and trimmed vehicle panels are compared against reference numerical results. Finally, interior noise levels in bare and trimmed configurations are predicted and results from a noise path contribution analysis are presented.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p534.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p789" class="affilation"></a>Efficient Wave Based Models for Acoustic Scattering and Transmission Problems Using Point Source and Planewave Excitation</h2>
<h3>Bart Bergen, Bert Van Genechten, Bert Pluymers, Dirk Vandepitte, Wim Desmet</h3>
<p class="affilation">K. U. Leuven - Department of Mechanical Engineering, Celestijnenlaan 300B, B-3001 Leuven, Belgium</p>
<p><b>ABSTRACT</b><br>
The wave based method (WBM) is an efficient deterministic prediction method for the analysis of steady-state acoustic problems. It offers an alternative to the finite element and boundary element method, especially in the mid-frequency range, where these element based methods are impaired by their computational burden. This paper discusses the use of new source formulations in WB models for two-dimensional unbounded acoustic problems. These source formulations allow the WBM to tackle general acoustic radiation and transmission problems. Numerical validation examples illustrate the advantageous properties of the considered approach.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p789.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p428" class="affilation"></a>On the Use of a High-Order Finite Element - Wave Based Method for Interior Acoustic Cavity Analysis</h2>
<h3>Bert Pluymers, Dirk Vandepitte, Paul Sas, Wim Desmet</h3>
<p class="affilation">K.U.Leuven - Department of Mechanical Engineering, Celestijnenlaan 300B, 3001 Leuven, Belgium</p>
<p><b>ABSTRACT</b><br>
This paper discusses the use of wave based prediction methods for the analysis of steady-state interior acoustic problems. Conventional element based prediction methods, such as the finite element method (FEM), are commonly used, but are restricted to low-frequency applications. The wave based method (WBM) is an alternative deterministic technique which is based on the indirect Trefftz approach. The WBM is computationally very efficient, allowing the analysis of problems at higher frequencies. The efficiency of the WBM is most pronounced for problems of moderate geometrical complexity. For the analysis of problems with a more complex geometry, a hybrid finite element-wave based method is developed. This hybrid approach combines the strengths of the two methods, namely, the high computational efficiency of the WBM and the ability of the FEM to model problems of arbitrary geometrical complexity. Up till now, only low-order FE models have been coupled with WB models. This paper discusses the application of more accurate high-order FE schemes in the hybrid FE-WB approach. The performance of the resulting high-order hybrid method will be illustrated by means of a numerical validation example.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p428.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p487" class="affilation"></a>Application of Modal Model Reduction for Hybrid Structural Finite Element - Acoustic Wave Based Models</h2>
<h3>Bert Van Genechten, Bert Pluymers, Caroline Vanmaele, Dirk Vandepitte, Wim Desmet</h3>
<p class="affilation">K.U.Leuven - Dept. of Mechanical Engineering, Celestijnenlaan 300B, 3001 Heverlee (Leuven), Belgium</p>
<p><b>ABSTRACT</b><br>
This paper presents a newly developed hybrid simulation technique for coupled structural-acoustic analysis, which applies a wave based model for the acoustic cavity and a modally reduced higher order finite element model for the structural part. The resulting hybrid model benefits from the computational efficiency of the wave based method, while retaining the finite element method’s ability to model the structural part of the problem in great detail. Application of this approach to the analysis of a cavity-backed plate assembly shows the improved computational efficiency as compared to classical finite element procedures and illustrates the potential of the hybrid method as a powerful tool for the analysis of coupled structural-acoustic systems.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p487.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p397" class="affilation"></a>Wave-Based Discontinuous Galerkin Methods in the Frequency Domain with Application to Flow Acoustics</h2>
<h3>G. Gabard</h3>
<p class="affilation">Institute of Sound and Vibration Research, University of Southampton, Southampton, SO17 1BJ, U.K.</p>
<p><b>ABSTRACT</b><br>
Prediction of aircraft noise relies on the simulation of noise propagation through air flows. Computational techniques for flow acoustics (or aeroacoustics) have been mainly based on finite element methods for the linear full potential theory, or on finite difference schemes and Discontinuous Galerkin methods for the linearized Euler equations in the time domain. However, currently available numerical methods are difficult to apply to full-scale realistic configurations. For instance predictions of noise radiation from aircraft engines including the scattering by the pylon and the wing are still too expensive to be carried out systematically for design purposes. This paper presents a novel discontinuous Galerkin method in the frequency domain which uses local plane wave solutions of the problem at hand to approximate the solutions. This departs significantly from previous computational schemes based on polynomial interpolation techniques. The method is formulated for the linearized Euler equations and is therefore able to deal with very general mean flow configurations. The dispersion relation of the linearized Euler equations is used to discretize the solution and the trial function, it also forms the basis for the numerical flux splitting. Simple validation results of the wave-based discontinuous Galerkin method will be presented in order to illustrate the accuracy of the method. Examples of realistic applications will also be presented. In particular the problem of noise propagating through jets will be considered.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p397.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p685" class="affilation"></a>Natural Frequency Statistics of Plates with Bounded Uncertain Properties Using Interval Analysis</h2>
<h3>Geoffrey Lucas, Nicole Kessissoglou, Wei Gao</h3>
<p class="affilation">School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney, NSW 2052, Australia</p>
<p><b>ABSTRACT</b><br>
The vibrational characteristics of a dynamic system can be sensitive to variations in parameters such as its material properties and this sensitivity increases as the frequency increases. Since, for most practical structures, their geometric or material properties are not exactly known, prediction methods for the dynamic response of a structure with uncertain properties generally requires some model for the statistics of its natural frequencies. In this paper, the effect of uncertainty in the material parameters and dimensions of a plate on the variability in its vibrational characteristics is presented using a technique called the interval factor method. With this method, the lower bound, upper bound and mean values of the natural frequencies and modeshapes have been determined where the density, Young’s modulus and plate thickness were allowed to vary within a predefined band.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p685.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p462" class="affilation"></a>Efficient Numerical Models for Investigating Statistics of Random Dynamic Systems</h2>
<h3>Julio A. Cordioli (1), Robin S. Langley (2), Vincent Cotoni (1), Samir N. Y. Gerges (3)</h3>
<p class="affilation">(1) ESI US R&D Inc., San Diego, CA, 92130, USA (2) Depto of Engineering, Univ. of Cambridge, Trumpington St, Cambridge CB2 1PZ, UK (3) Federal University of Santa Catarina, Florianopolis - SC, Brazil</p>
<p><b>ABSTRACT</b><br>
The study of random dynamic systems usually requires the definition of an ensemble of structures and the solution of the eigenproblem for each member of the ensemble. If the process is carried out using a conventional numerical approach, the computational cost becomes prohibitive for complex systems. In this work, an alternative numerical method is proposed. The results for the response statistics are compared with values obtained from a detailed stochastic FE analysis of plates. The proposed method seems to capture the statistical behaviour of the response with a reduced computational cost.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p462.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p735" class="affilation"></a>Modelling Complicated Systems with Partly Unknown Dynamic Properties as “Structural Fuzzy”</h2>
<h3>Lars Friis (1,2), Mogens Ohlrich (1)</h3>
<p class="affilation">(1) Acoustic Technology, Ørsted DTU, Technical University of Denmark, Building 352, DK-2800 Kgs. Lyngby, Denmark (2) Widex A/S, Ny Vestergårdsvej 25, DK-3500 Værløse, Denmark</p>
<p><b>ABSTRACT</b><br>
From experiments it is well-known that the vibration response of complicated, built-up systems often show more damping than structural losses in the components can account for. The “Theory of structural fuzzy” is intended for modelling of such high damping induced by resonant structures. When modelling a complicated system, it is divided into a deterministic master structure and one or more fuzzy substructures, which are known only in some statistical sense. In the present paper the theory of fuzzy structures is outlined and a special method of including spatial memory in the modelling of fuzzy substructures with continuous boundaries is examined. The high damping effect of the structural fuzzy is demonstrated by a numerical model of a simple master structure with fuzzy attachments. It is shown that the introduction of spatial memory reduces the damping effect of the fuzzy and may cause the resonance frequencies of the complex system to increase.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p735.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p671" class="affilation"></a>High Frequency Approximations for Treating Acoustic Radiation or Scattering Problems with the Boundary Element Method</h2>
<h3>Martin Ochmann (1), Bodo Nolte (2), Ralf Burgschweiger (1), Ingo Schäfer (2)</h3>
<p class="affilation">(1) University of Applied Sciences Berlin, Department of Mathematics - Physics - Chemistry, Luxemburger Str. 10, 13353 Berlin, Germany (2) Forschungsanstalt der Bundeswehr für Wasserschall und Geophysik - Federal Armed Forces Underwater Acoustics and Marine Geophysics Research Institute, Klausdorfer Weg 2-24, D-24148 Kiel, Germany</p>
<p><b>ABSTRACT</b><br>
The numerical prediction of sound fields radiated or scattered from complex shaped structures into the three-dimensional space can be performed effectively by using the boundary element method (BEM). However, at high frequencies, it is often necessary to deal with discretized structures consisting of many thousand finite surface elements, in order to ensure a sufficient number of elements per wavelength. Consequently, the computational cost of the method grows considerably with increasing frequency. Thus, suitable approximations tailored to the high frequency range can reduce computational time drastically. Several such techniques are known. In this paper, the theoretical framework of the Rayleigh integral and the plane wave approximation (PWA) for the radiation problem will be explained and compared with each other. For the scattering problem, the so-called Kirchhoff approach is often used. On the other hand, the Rayleigh integral and the PWA can also be applied to the scattering problem, since it can be formulated as an equivalent radiation problem. The theory of the three approximations will be presented and compared with respect to the scattering problem, too. In the present and in an accompanying paper, the Kirchhoff approach and the PWA will be applied to the scattering of plane waves from cylindrical shells located in free space for a frequency range up to 100 kHz.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p671.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p149" class="affilation"></a>Physics-Based Numerical Method for Analyzing Mid-Frequency Acoustic Radiation</h2>
<h3>Stephen D. O’Regan</h3>
<p class="affilation">Naval Surface Warfare Center, Carderock Division, Carderock, MD 20817, USA</p>
<p><b>ABSTRACT</b><br>
As industrial noise sources have increased year by year, tolerance for noise levels by industry, government, and the general population has decreased. Ever more stringent noise regulations are driving up the cost of design and manufacturing. To reduce this cost, designers look to the NVH community for sophisticated numerical tools to predict noise over a broad frequency range. This work focuses on mid-frequency acoustic analysis tools. Boundary, finite, and infinite element methods have proven useful for solving the 3D acoustic wave equation at low frequencies. For high frequency, localized formulations such as plane-wave and ray-tracing methods have been applied. These methods are impractical, inaccurate, or both for treating mid-frequency problems. Low-frequency methods make very large demands on computer processing while high-frequency methods do not account for nonlocal effects. Several investigators have proposed applying a hybrid low/high frequency approach to solve the mid-frequency problem. This approach essentially applies mathematical functions that match the fluid impedance at the low and high ends of the frequency spectrum and provide a mathematically smooth bridge between them. The drawback to this approach is that it does not address the physics unique to mid-frequency, and therefore it cannot provide very accurate solutions. The goal of this work is to develop a method for efficiently addressing a class of mid-frequency vibration. This class deals with structural surfaces characterized by a moderate number of major sections in which the spatial wavenumber vibration content is bandlimited and known a priori. A physics-based strategy will be followed to capture the fluid-structure interaction character that is peculiar to the mid-frequency range.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p149.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p672" class="affilation"></a>Generation and Validation of Acoustic 3D WBT Models of a SUV Driver Compartment from SEA Models</h2>
<h3>Thorsten Bartosch, Gregor Müller</h3>
<p class="affilation">MAGNA STEYR Fahrzeugtechnik AG & Co KG, 8041 Graz, Austria</p>
<p><b>ABSTRACT</b><br>
The wave based technique (WBT) constitutes an upcoming simulation technique which results in reduced simulation time and reduced simulation errors compared to finite element (FE) approaches for solving Helmholtz problems. The finite element analysis represents a method which basis functions approximate the boundaries exactly. On the other hand the WBT basis functions are a solution of the Helmholtz equation but its weighted superposition fulfil the boundaries only approximately. However it takes much time to generate a WBT model of a driver compartment of complex vehicle interior geometries because of the requirement that each WBT domain must be a convex volume. Therefore a compromise has to be found between real vehicle surface geometry and its simplifications to coarse box models. A process is introduced which allows the generation of WBT models including the set up of the required boundary conditions based on complete vehicle AutoSEA models. As an example the WBT analysis is applied for a complex SUV driver compartment and validated. The model is used to calculate the over all damping factor of the cavity and the acoustic performance of a head liner is analysed with respect to human in-cabin communications.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p672.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p535" class="affilation"></a>Modeling Methods for Vibro-Acoustic Analysis of Commercial Aircrafts</h2>
<h3>V. Cotoni (1), B. Gardner (1), J. P. Carneal (2), C. Fuller (2)</h3>
<p class="affilation">(1) ESI-US R&D, San Diego USA (2) Vibration and Acoustic Lab, Virginia Tech, Blacksburg USA</p>
<p><b>ABSTRACT</b><br>
This paper describes an ongoing program of work concerned with the development of improved methods for modelling the vibro-acoustic response of commercial aircraft structures at mid and high frequencies. The study is focused on the noise and vibration transmission in an actual section of a 737 Boeing aircraft, including trimmed sidewalls, stowage bins, and connected floor structure. Six transmission problems have been identified and two of them are presented in this paper: the transmission of vibrational energy into the stowage bins via the stowage bin tie rods, and the transmission of vibrational energy between the sidewall and floor panels through the floor beams. The different modelling approaches make use of the recently developed Hybrid FE-SEA method and general periodic SEA subsystem. In all test cases, the numerical predictions are compared with test and good agreement is observed.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p535.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p284" class="affilation"></a>The Coupling of a Hearing AID Loudspeaker Membrane to Visco-Thermal Air Layers</h2>
<h3>W.R. Kampinga, C. Bosschaart, Y. H. Wijnant, A. de Boer</h3>
<p class="affilation">University of Twente, Department of Mechanical Engineering, P.O. box 217, 7500 AE, Enschede, The Netherlands</p>
<p><b>ABSTRACT</b><br>
Hearing aids and their components are becoming smaller. This presents new problems for the acoustical components, such as the loudspeaker. A circular membrane of a hearing aid loudspeaker is modeled in this paper. Neglecting air influences, the membrane and its suspension behave as a mass spring system. However, under operating conditions, thin layers of air on both sides of the membrane influence its behavior. Air can enter and leave these layers at certain locations on the circular edge of the layer. Since these air layers are thin, visco-thermal effects may have to be taken into account. Therefore, the air layers are not modeled by the wave equation, but by the low reduced frequency model that takes these visco-thermal effects into account. The equations of this model are solved in a polar coordinate system, using a wave-based method. The other acoustical parts of the hearing aid loudspeaker, and the membrane itself are modeled by simple lumped models. The emphasis in this paper is on the coupling of the visco-thermal air layer model to the mechanical model of the membrane. Coupling of the air layer to other acoustical parts by using an impedance as boundary condition for the layer model, is also described. The resulting model is verified by experiments. The model and the measurements match reasonably well, considering the level of approximation with lumped parts.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p284.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p637" class="affilation"></a>Prediction of Breakout Noise from End Plate of an Expansion Chamber Using Coupled FE/BE Analysis</h2>
<h3>Deepak W. Pande (1), Dhanesh N. Manik (2)</h3>
<p class="affilation">(1) Department of Mechanical Engineering, Govt. College, Aurangabad, India (2) Department. of Mechanical Engg., Indian Institute of Technology Bombay, Mumbai, India</p>
<p><b>ABSTRACT</b><br>
Sound pressure levels of breakout noise due to flexible end plate of an expansion chamber are computed using coupled FE/BE analysis; boundary element method was used to obtain the pressure driving the end plate; coupled analysis was used to predict the vibration of the end plate, considering acoustic loading on both of its sides; acoustic pressure in the exterior field was computed using Rayleigh’s integral. Inclusion of the chamber cavity in the geometry of the solution domain enabled consideration of actual pressure distribution over the end plate and acoustic loading on the interior side of the end plate. Cases corresponding to very high and very low values of the radiated sound pressure levels of breakout noise were analyzed. Conditions of coincidence were identified corresponding to the highest value of radiated sound pressure level of breakout noise. At coincidence, three conditions are fulfilled simultaneously. First, the excitation frequency and the natural frequency of vibration of the end plate are equal. Second, the excitation frequency and the resonance frequency of the chamber cavity are equal. Third, the mode-type of vibration of the end plate (axisymmetric or diametral) and nature of distribution of the driving pressure (axisymmetric or otherwise) match with each other. Based on these observations, precautions to be taken while designing expansion chamber mufflers are suggested so the breakout noise can be kept to a minimum.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p637.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p201" class="affilation"></a>Recent Advances in IC-Engine Acoustic Source Characterisation</h2>
<h3>Hans Bodén</h3>
<p class="affilation">The Marcus Wallenberg Laboratory for Sound and Vibration Research, Aeronautical and Vehicle Engineering Department, KTH, SE-10044, Stockholm, Sweden</p>
<p><b>ABSTRACT</b><br>
This paper summarizes work performed at KTH over the years on source characterization for IC-engine exhaust and intake systems. An overview is made of recent advances in experimental and simulation methods for determination of acoustic source data. These include a source model which can consider weakly non-linear sources and application of 1-D CFD codes for extracting source data. Examples are presented for both exhaust and intake systems and for different types of engines. The results show that reasonably accurate results can be obtained using 1-D CFD codes to extract acoustic source data and that the newly developed non-linear multi-load technique has got advantages over the traditional two-load technique for determining source data from experiments.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p201.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p270" class="affilation"></a>FRITAmuff: A Comprehensive Platform for Prediction of Un-Muffled and Muffled Exhaust Noise of IC Engines</h2>
<h3>M. L. Munjal, S. N. Panigrahi, R. N. Hota</h3>
<p class="affilation">Facility for Research in Technical Acoustics, Department of Mechanical Engineering, Indian Institute of Science, Bangalore -560012, India.</p>
<p><b>ABSTRACT</b><br>
Prediction of un-muffled and muffled noise from internal combustion engines requires knowledge of the acoustic attenuation performance of the muffling system along with the engine noise source characteristics. Here, in addition to the conventional cascade type analysis, a novel geometry-based user-friendly scheme has been employed for analyzing multiply-connected elements. It uses the geometry of the muffler along with a numerical algorithm to produce the overall transfer matrix of the element. This scheme has been used in conjunction with the transfer matrix based muffler program, which has a large number of predefined, parameterized elements including the variable area perforated elements, to analyze the entire exhaust system of the automobile. The source characteristics of the engine, as functions of the engine’s physical and thermodynamic parameters, are predicted numerically by means of a two load method and incorporated as empirical formulas into the scheme to predict both the un-muffled and muffled noise with any muffler configuration. Thus, the insertion loss of the muffler system is evaluated for different speed orders or frequencies. Though this methodology may not be able to predict the actual noise spectra accurately, yet this is good enough from the practical point of view, as manufacturers are generally interested in the total noise level. A Graphical User Interface (GUI) has been prepared for ready use. This computational platform, FRITAmuff, is applicable for turbocharged as well as the naturally aspirated engines.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p270.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p482" class="affilation"></a>Sound Propagation in Narrow Channels with Arbitrary Cross Sections and Superimposed Mean Flow with Application to Charge Air Coolers</h2>
<h3>Magnus Knutsson (1), Mats Åbom (2)</h3>
<p class="affilation">(1) Volvo Car Corporation, SE-405 31 Göteborg, Sweden (2) KTH CICERO, the Marcus Wallenberg Laboratory for Sound and Vibration Research, SE-100 44 Stockholm, Sweden</p>
<p><b>ABSTRACT</b><br>
Charge air coolers are used on turbo charged IC-engines to enhance the overall gas exchange performance. The cooling of the charged air results in higher density and thus volumetric efficiency. Important for petrol engines is also that the knock margin increases with reduced charge air temperature. A property that is still not very well investigated is the sound transmission through a charge air cooler. The pressure drop in the narrow cooling tubes results in frequency dependent resistive effects on the transmitted sound that is non negligible. As the cross sections of the cooling tubes are neither circular nor rectangular, no analytical solution accounting for a superimposed mean flow exists. The cross dimensions of the connecting tanks, located on each side of the cooling tubes, are large compared to the wavelength for engine breathing noise, here including frequencies up 1.5 kHz, so three dimensional effects are important. In this study an acoustic two-port for sound propagation in narrow tubes, including the effect of viscous and thermal boundary layers, is calculated utilizing a 2D finite element solution scheme. Analytical solutions for circular cross sections are additionally calculated for comparison. The two-port is thereafter combined with 3D acoustic finite element modelling to represent the transmission properties of the charged air when passing the complete air-to-air charge air cooler. From this a linear frequency domain model for the entire charge air cooler is extracted in the form of a two-port. The frequency dependent transmission loss is calculated and compared with corresponding experimental data. Finally, there is a discussion of the results and the potential of using charge air coolers to control the acoustic response of intake systems.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p482.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p797" class="affilation"></a>Transfer Matrix Method for Dual-Chamber Mufflers</h2>
<h3>Mihai Bugaru, Ovidiu Vasile</h3>
<p class="affilation">Department of Mechanics, University of Bucharest, Bucharest, Romania</p>
<p><b>ABSTRACT</b><br>
Mufflers are widely used for exhaust noise attenuation in vehicles, machinery and other industrial elements. Modelling procedures for accurate performance prediction had led to the development of new methods for practical muffler components in design. Plane wave based models such as the transfer matrix method (TMM) can offer fast initial prototype solutions for muffler designers. In the present paper the authors present an overview of the principles of TMM for predicting the transmission loss (TL) of a muffler. The predicted results agreed in some limits with the experimental data published in literature.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p797.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p586" class="affilation"></a>One Design of a Silencer for Attenuating Fan Noise</h2>
<h3>Tian Qi, Yafeng Wu, Ye Li</h3>
<p class="affilation">Box 207, Data Processing Center, School of Engine and Energy, Northwestern Polytechnical University, Xi’an 710072, China</p>
<p><b>ABSTRACT</b><br>
The paper introduces one design of a silencer for attenuating fan noise and the implementation result. A denoising experiment was carried out on the intake and discharge noise of the fan which is used to cool a certain apparatus in an aircraft application. The silencer parameters are calculated in detail and comparative measurements are carried out. The experimental results show that the silencer can efficiently attenuate the noise in a wide frequency band.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p586.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p219" class="affilation"></a>Study on the Simulation Design Method About Exhaust Muffler of Vehicle</h2>
<h3>Yuan Zhaocheng, Ma Jiayi, Li Shengcheng, Fang Hua</h3>
<p class="affilation">Department of Internal Combustion Engine, Automotive College, Jilin University, 5988 Renmin Street, Changchun city, China</p>
<p><b>ABSTRACT</b><br>
In this paper, the performance of attenuating sound about automotive exhaust mufflers were simulated with the method of boundary elements, and the flow performance of muffler were simulated with the method of CFD. The results were validated with the experiment data. So it indicated that the simulation model is correct and the method is reasonable. Based on the experiment validation of the transmission loss of muffler, the frequencies of sound should be controlled and the possibility of amelioration were found out for exhaust muffler by the simulation method of boundary element. The reason of causing an attenuation trough for this muffler were analyzed by the acoustic model and sound pressure map analysis methods, and the improvement is put forward with the control measure of long duct standing wave, and the muffler design method and simulation are explored in this process. And the effect of flow excited noise was studied, some useful results were gotten out by the experiment and the simulation.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p219.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p233" class="affilation"></a>Application of Dual Reciprocity Boundary Element Method to Predict Acoustic Attenuation Characteristics of Silencers with Complex Flow</h2>
<h3>Zhenlin Ji, Xueren Wang</h3>
<p class="affilation">School of Power and Energy Engineering, Harbin Engineering University, Harbin, Heilongjiang 150001, P. R. China</p>
<p><b>ABSTRACT</b><br>
The complex flow and sound fields inside silencers require a three-dimensional numerical method for the accurate prediction of acoustic attenuation characteristics of silencers. In the present study, the dual reciprocity boundary element method (DRBEM) is developed to predict and analyze the acoustic attenuation characteristics of the silencers with higher Mach number subsonic flow. In order to overcome the singularity in the single domain BEM for complex silencer analysis and to reduce the computational time, the substructure approach is employed. The effect of flow on acoustic attenuation performance of the silencers is investigated.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p233.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p179" class="affilation"></a>Fractional Fourier Transforms for Spectral Analysis of Music Signals</h2>
<h3>Charu (1), V. G. Das (2), V. Prem Pyara (3), V. Prem Kumari (4)</h3>
<p class="affilation">(1) Jaypee Institute of Engineering and Technology, Raghogarh, India (2) Dayalbagh Educational Institute, Agra, India (3) Department of Electrical Engineering, Dayalbagh Educational Institute, Agra, India (4) Department of Music, Dayalbagh Educational Institute, Agra, India</p>
<p><b>ABSTRACT</b><br>
A new technique for spectral analysis is proposed for application to music signals. The frequency transform presented in this work eliminates the need for multiplications, by requiring the sole use of additions making the ASIC (Application Specific Integrated Circuit) implementation simpler. The transform is generalized and can be applied to any band limited spectral analysis. The proposed Fractional Fourier Transform shows almost no error in the analysis when compared to standard Discrete Fourier Transform.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p179.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p53" class="affilation"></a>Wavelet Design for Music Perception Applied to Indian Classical Music</h2>
<h3>Charu (1), V. G. Das (2), V. Prem Pyara (3), V. Prem Kumari (4)</h3>
<p class="affilation">(1) Jaypee Institute of Engineering and Technology, Raghogarh, India (2) Dayalbagh Educational Institute, Agra, India (3) Department of Electrical Engineering, Dayalbagh Educational Institute, Agra, India (4) Department of Music, Dayalbagh Educational Institute, Agra, India</p>
<p><b>ABSTRACT</b><br>
Wavelet Transforms provide a time-frequency analysis with constant Q factor. Although these transforms require intensive computational effort, they are efficient in terms of accuracy. Here, a wavelet is designed for the estimation of frequency of audio signals. This wavelet provides a resolution of 1% which is comparable to human auditory system and is applied here to Indian Classical Music. For this style of music, the task of frequency estimation is comparatively difficult as the note frequencies are not fixed but vary at fixed ratios with respect to the base frequency chosen by the performer. The obtained results match the theoretically expected frequencies.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p53.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p608" class="affilation"></a>Towards a Music Synthesizer Controlled by Timbral Adjectives</h2>
<h3>David M. Howard, Alastair C. Disley, Andy D. Hunt</h3>
<p class="affilation">Audio Lab, Intelligent Systems Research Group, Department of Electronics, University of York, Heslington, York, YO10 5DD, United Kingdom</p>
<p><b>ABSTRACT</b><br>
For many musicians, the control parameters associated with electronics synthesis systems are not conducive to their creative processes. Filter setting, resonance controls, frequency or amplitude modulation settings, different “raw” waveforms and varieties of noise are examples of what have emerged as synthesizer controllers designed by engineers. Musicians describe the timbre of sounds using everyday adjectives such as bright, mellow, brash, warm and fuzzy. This paper will describe the development of a pilot music synthesis system based on Pure Data (PD) which uses timbral adjectives as its controllers. The effect that the controls have on the acoustic output is based on a series of listening tests carried out with musicians to elicit commonalities in how they use adjectives to describe the sounds of existing musical instruments. The listening tests were carried out over the internet. To validate the use of the internet in this way, a control group were asked to carry out the listening test alone and in the presence of an investigator in order to establish whether there was any difference in the data obtained. The average differences were smaller than the step size of the test itself, confirming the validity of the internet as a listening test vehicle. The listening test data have been analysed using multidimensional scaling and principal component analysis to establish which adjectives account for the greatest degree of segregation across the listeners and the sounds under investigation. These adjectives are the controllers for the synthesizer, and a number of sound examples will be played to illustrate the effectiveness of the final prototype synthesis system.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p608.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p756" class="affilation"></a>Nonlinear Vibration Analysis in Acoustics</h2>
<h3>J. Petrolito (1), K. A. Legge (1), M. T. Harrison (2)</h3>
<p class="affilation">(1) Department of Civil Engineering and Physical Sciences, La Trobe University, Bendigo 3552, Australia (2) Research School of Biological Sciences, Australian National University, ACT 2601, Australia</p>
<p><b>ABSTRACT</b><br>
Mechanisms of nonlinear coupling between the normal modes of vibrating mechanical structures have been explored, previously particularly in the context of struck idiophones (percussive instruments). However, the analysis of the vibrations resulting from impulsive loads has been restricted by our ability to solve the nonlinear equations of motion. In recent times, numerical methods for solving the equations have burgeoned, and we are now in a position to apply the methods to structures of interest such as musical plates and gongs. In this paper, we consider the nonlinear coupling of modes of vibration whereby energy is transferred between the normal modes of a kinked bar. A finite element analysis package is employed to analyse the response. The results confirm that initially missing modes of vibration are generated through nonlinear coupling mechanisms.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p756.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p686" class="affilation"></a>A Study of Input Mobility Functions at a Violin’s Bridge</h2>
<h3>Jie Pan, Robert Wilkins</h3>
<p class="affilation">School of Mechanical Engineering, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia</p>
<p><b>ABSTRACT</b><br>
Experimental comparison of individual notes from different violins has revealed some differences between the tonal qualities of violins. These differences offer clues towards an objective determination of a violin’s acoustical quality. This paper reports some preliminary findings of the correlation between the tonal quality and input mobility functions at locations where the strings attach of the bridge of two different violins. It is demonstrated that the mobility functions are related to the violin’s bowing sensitivity and to the overall sound radiation to the performer and listeners.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p686.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p628" class="affilation"></a>The ‘Didjeriduo’: Musical Implications of a Three-Port Branched Duct</h2>
<h3>Markus Schneider, John Smith, Joe Wolfe</h3>
<p class="affilation">School of Physics, University of New South Wales, Sydney, NSW 2052, Australia</p>
<p><b>ABSTRACT</b><br>
The didjeridu (or didgeridoo or yidaki), a musical instrument originally played in parts of Northern Australia, is unusual in the extent to which standing waves in the bore and the player’s vocal tract are coupled. Skilled players use resonances of the vocal tract to modify the spectral envelope of the output sound, which gives the instrument its unique timbre. The central bore of these instruments is largely produced by termites eating out the interior of small eucalypt trees. This produces a highly irregular and somewhat flared bore, both of which features are important to the performance quality of the instrument. Occasionally a forked section of a tree is suitably eaten by termites. This allows the manufacture of a ‘forked didjeridu’ or ‘didjeriduo’ with a branched bore and two available mouthpieces. It is then possible for a single player to produce changes in pitch and timbre, either by adjusting their lip tension to select different bore resonances, or by using the heel of his hand to close the other mouthpiece. It is even possible for two players to play the same instrument simultaneously. Here we present detailed measurements of the acoustic input impedance of a forked didjeridu. Numerical modelling suggests how the presence of a branched duct might alter the perceived quality of an instrument.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p628.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p248" class="affilation"></a>Geometric Shape Identification for Multi-Mode Tuning of Percussion Instrument Bars</h2>
<h3>Rodney D. Entwistle, Stephen R. McGrechan</h3>
<p class="affilation">Department of Mechanical Engineering, Curtin University of Technology, Perth, WA 6845, Australia</p>
<p><b>ABSTRACT</b><br>
The lower registers of the marimba, vibraphone and xylophone consist of percussion bars that have the lower three bending modes tuned. Tuning is achieved by removing material from the underside of the beam. Accurate prediction of the geometry of this undercut would be necessary for automated tuning. This paper models the beam free vibrations and accurately predicts the non-unique shape of the undercut that results in the simultaneous tuning of the three frequencies. Accurate natural bending frequencies are modelled using receptance sub-structuring and Timoshenko beam receptances. Allowance for the frequency dependency of the elastic modulus of wood is made. Search algorithms are implemented to locate the geometric shape of the undercut curve that satisfies the multi-mode frequency requirements. The sensitivity of the frequencies to dimensional variations is reported. Manufacture of aluminium and wooden bars show that the predictions are very accurate and suitable for the basis of automated manufacture.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p248.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p565" class="affilation"></a>Experimental Study of the Flow-Excited Acoustical Lock-in in a Corrugated Pipe</h2>
<h3>Vincent Debut (1), José Antunes (1), Miguel Moreira (2)</h3>
<p class="affilation">(1) Institute of Nuclear Technology, Applied Dynamics Laboratory, ITN/ADL - 2686, Sacavem codex, Portugal (2) Polytechnic Institute of Setubal, Department of Mathematics, IPS/EST/DM - 2914-761, Setubal, Portugal</p>
<p><b>ABSTRACT</b><br>
Preliminary experiments to study the aeroacoustic interaction in a corrugated pipe subjected to axial flow are reported. A number of pipes of different diameters, lengths and corrugation pitches and shapes are tested. Results are presented in the light of previous work and the aeroacoustic instability Strouhal numbers are evaluated. We notice that not a single value St is applicable for all tested tubes and discuss the qualitative differences observed.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p565.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p632" class="affilation"></a>An Investigation on the Sensor Proximity Effect in the BEM- Based NAH</h2>
<h3>Agustinus Oey (1), Jeong-Guon Ih (1), Hae-Won Jang (1), Bong-Ki Kim (2)</h3>
<p class="affilation">(1) Center for Noise and Vibration (NoViC), Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Korea (2) Korea Institute of Machinery and Materials (KIMM)</p>
<p><b>ABSTRACT</b><br>
Near-field acoustical holography (NAH) using the boundary element method (BEM) is known to be very powerful in the source identification and visualization of many practical vibro-acoustic sources having irregular boundaries. In order to get rich information on the radiated wave components, both of propagating and evanescent waves, sensors should be positioned as close as possible to the source surface in principle. Therefore, it is beneficial to utilize a conformal hologram plane to the source surface; however, the usual way to measure the field data radiated from an irregular shaped source is to adopt a regular hologram plane in many cases for measurement ease. In such circumstances, the distance between sensors and the nearest point of the source surface cannot be maintained same for all measurement points in general. Consequently, different degree of information on propagating and non-propagating wave components will be detected by sensors at different positions. In this work, a preliminary theoretical and experimental investigations were conducted on such sensor proximity effect to the reconstruction errors in using the BEM-based NAH for interior problem.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p632.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p791" class="affilation"></a>Acoustic Modelling of Machines Using the Inversion Method</h2>
<h3>Dariusz Pleban</h3>
<p class="affilation">Central Institute for Labour Protection-National Research Institute, ul. Czerniakowska 16, 00-701 Warsaw, Poland</p>
<p><b>ABSTRACT</b><br>
Issues related to the development of acoustic models of machines are important factors both in the design of low-noise machines and in the prediction of machines noise. The acoustic modelling of machines may be carried out using a set of omni-directional substitute sound sources, located in points related to the functional elements of machines. The optimal parameters of these sources may be determined using an inversion method. To calculate these parameters by using the inversion method one must know the real distribution of sound pressure around the machine. This requires the determination, on the surface of hemisphere, of both the distribution of the amplitude of sound pressures, as well as the distribution of phase shift angles between acoustic signals. Computer simulations yield optimal parameters (sound power) for the individual omni-directional sound sources. Using the calculated parameters of the substitute sources it is possible to determine the radiation characteristics and to carry out the acoustic assessment of the machine. The results of the acoustic modelling of machines using the inversion method and computer simulations regarding the effect of the distance between the substitute sources on the emission sound pressure levels, as well as the results of the acoustic assessments of machines are presented in the paper.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p791.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p747" class="affilation"></a>Application of Diagnostic Techniques in Improving Vibration and Acoustic Prediction</h2>
<h3>F. Martinus (1), P. Mehta (1), D. W. Herrin (2), A. F. Seybert (2)</h3>
<p class="affilation">(1) The Trane Company, 3600 Pammel Creek Rd., La Crosse, WI 54650, USA (2) Department of Mechanical Engineering, University of Kentucky, 151 RGAN Building, Lexington, KY 40506, USA</p>
<p><b>ABSTRACT</b><br>
Numerical techniques in vibration and noise control have traditionally been implemented in a prediction-only role, primarily using the finite and boundary element methods. However, the key to this approach is to accurately represent not only the physical system but also the excitation (structural and airborne), which is challenging in most cases. Recent work has shown that diagnostic and holography techniques can be used when limited information is available regarding the system. For example, contribution analysis can be performed to assess which parts of the system are the potentially dominant noise sources. Additionally, the inverse boundary element method can be used to accurately predict both structural and aeroacoustic sources. For structural problems where excitations are not known, transfer path analysis can be performed to complement a forward finite element analysis. Several examples using a diesel engine, an engine cover, and a water-cooled chiller are presented.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p747.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p741" class="affilation"></a>Weighted Statistically Optimised Near Field Acoustic Holography with Pressure-Velocity Probes</h2>
<h3>Finn Jacobsen (1), Xinyi Chen (1), Virginie Jaud (2)</h3>
<p class="affilation">(1) Acoustic Technology, Ørsted DTU, Technical University of Denmark, Building 352, DK-2800 Kgs. Lyngby, Denmark (2) Extraction et Exploitation de l’Information en Environnements Incertains, École Nationale Supérieure d’Ingénieurs des Études des Techniques d’Armement, 2 rue François Verny, F-29806 Brest Cedex 9, France</p>
<p><b>ABSTRACT</b><br>
Statistically optimised near field acoustic holography (SONAH) differs from conventional near field acoustic holography (NAH) by avoiding discrete spatial Fourier transforms. Both NAH and SONAH are based on the assumption that all sources are on one side of the measurement plane whereas the other side is source free. An extension of the SONAH procedure based on measurement with an array of pressure-velocity probes has recently been suggested. The pressure-velocity method makes it possible - within limits - to distinguish between sources on the two sides of the array and thus suppress the influence of extraneous noise coming from the `wrong’ side. This paper examines the possibility of improving the performance of the method by modifying some of the parameters used in determining the SONAH transfer matrix.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p741.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p60" class="affilation"></a>Research on the Theories of BEM Based Cyclostationary Near Field Acoustic Holography</h2>
<h3>Haibin Zhang, Weikang Jiang, Quan Wan</h3>
<p class="affilation">State Key Laboratory of Mechanical System and Vibration, Shanghai Jiaotong University, No.800, Dongchuan Road, Shanghai 200240, P. R. China</p>
<p><b>ABSTRACT</b><br>
The cyclo-stationary vibrational signal modulated by other signals is an example of a non-stationary signal found frequently in internal combustion engines and rotating machinery. The modulation frequency component may be extracted from the total signal using second order cyclic statistics. In previous research, the authors used the cyclo-stationary near field acoustic holography (CYNAH) technique in which the cyclic spectral density functions were used to reconstruct physical quantities. In this paper the CYNAH method is combined with the boundary element method to overcome the limitations of the planar CYNAH method. The methods used in the conventional BEM based NAH to overcome non-uniqueness and the ill-posed nature of the reconstruction are also implemented here. Results of a simulation show satisfactory agreement between computed and analytical values.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p60.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p785" class="affilation"></a>Plate Moduli Estimation Using Nearfield Acoustic Holography Techniques</h2>
<h3>Jean Claude Carmona (1), Daniel Mazzoni (2), Julien Caillet (3)</h3>
<p class="affilation">(1) Laboratoire des Sciences de l’Information et des Systèmes, UMR CNRS 6168, Ecole Nationale Supérieure des Arts et Métiers, 13100 Aix en Provence, France (2) Laboratoire des Mécanique et d’Acoustique, UPR CNRS 751, Ecole Centrale de Marseille, 13451 Marseille cedex 20, France (3) Eurocopter, 13610 Marignane, France</p>
<p><b>ABSTRACT</b><br>
In this paper, we present and discuss inverse methods to identify the elastic constants of an orthotropic panel through vibration testing. We shall focus on a method working either in high frequency or in low frequency domains. The principle is to use a correlation index between the Fourier transform of the spatial vibrational field of a plate, and a parameterized set of inhomogeneous damped waves, called IWC (inhomogeneous wave correlation) in order to estimate the plate elastic moduli, using therefore a nonlinear identification method. Nearfield acoustic holography (NAH) techniques provide the necessary experimental data. A comparison with a frequency modal approach is discussed to validate the result thus obtained.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p785.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p815" class="affilation"></a>ACOUSTIC HOLOGRAPHY BASED ON THE INVERSE-BEM FOR
THE SOURCE IDENTIFICATION OF MACHINERY NOISE</h2>
<h3>Jeong-Guon Ih</h3>
<p class="affilation">Centre for Noise and Vibration Control (NoViC) Department of Mechanical Engineering
Korea Advanced Institute of Science and Technology (KAIST)
Science Town
Daejeon 305-701
Korea</p>
<p><b>ABSTRACT</b><br>
Near-field acoustical holography (NAH) is an indirect method for the identification of<br>
<br>
vibro-acoustic properties of vibrating sound sources. In this technique, acoustic properties on<br>
<br>
the source plane can be inversely reconstructed, using the field pressure, which is measured on<br>
<br>
the measurement or hologram plane. The sound radiation, diffraction and transmission between<br>
<br>
the vibrating source and the measurement field can be modelled by the vibro-acoustic transfer<br>
<br>
matrix using the boundary element method (BEM). Consequently, the distribution of the<br>
<br>
surface velocities of the arbitrary shaped source, not on the near-field ‘source’ plane, can be<br>
<br>
reconstructed by multiplying the inverse of the calculated vibro-acoustic transfer matrix and the<br>
<br>
measured field pressure vector at any shape of near-field plane, including the conformal one.<br>
<br>
This type of conformal NAH technique has the following advantages compared with<br>
<br>
conventional NAH based on the spatial Fourier transform. One can deal with the complex<br>
<br>
shaped sources that cannot be described by separable coordinates; the pressure need not be<br>
<br>
measured in separable coordinates, thus a reduced number of measurements with uneven<br>
<br>
spacing is possible; reflections from all directions can be considered; concave regions of the<br>
<br>
source can be reconstructed; and wrap-around error due to the finite aperture size is not<br>
<br>
involved. In this paper, the basic nature of the involved problems is explained and a procedure<br>
<br>
for realizing the inverse identification of the machine noise source is demonstrated in several<br>
<br>
practical applications.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p815.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p340" class="affilation"></a>Experimental Application of High Precision K-Space Filters and Stopping Rules for Fully Automated PNAH</h2>
<h3>Rick Scholte, Ines Lopez, Bert Roozen, Henk Nijmeijer</h3>
<p class="affilation">Department of Mechanical Engineering, Eindhoven University of Technology, P.O. Box 513, 5600 MD Eindhoven, The Netherlands</p>
<p><b>ABSTRACT</b><br>
In general, inverse acoustic problems are ill-posed. Without any proper regularization action taken, noisy measurements result in an increasingly useless solution as the distance from the measurement plane to the desired source grows. Two distinctive steps take place in the regularization process for planar near-field acoustic holography (PNAH); first the low-pass filter function is defined and secondly a stopping rule is applied to determine the parameter settings of said filter. A number of well-known and newly developed filter functions and stopping rules are discussed and compared to one another, carefully listing the pros and cons. In acoustic imaging practice it has proven to be very hard to determine the right filter for a certain case combined with the automatic search for the near-optimal parameters. This paper presents a novel method that combines fitted filters for a broad number of possible experimental sources combined with highly efficient stopping rules, by taking advantage of k-space. Results based on actual measurements demonstrate the effectiveness, applicability and precision of the fully implemented and automated regularization process for PNAH. Implementations include modifications-of Tikhonov, exponential and truncation low-pass filters, L-curve, Generalised Cross--Validation (GCV) and the novel Cut-Off and Slope (COS) parameter selection methods for-PNAH.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p340.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p464" class="affilation"></a>Acoustic Holography and Complementary Boundary Conditions</h2>
<h3>Vincent Martin, Thibault Le Bourdon</h3>
<p class="affilation">Institut Jean Le Rond d’Alembert, CNRS/Paris VI, Place de la gare de Ceinture 78210 St Cyr l’Ecole, France</p>
<p><b>ABSTRACT</b><br>
Nearfield holography consists in measuring the acoustic pressure radiated near an extended sound source with the aim of deducing its vibratory velocity and, from this information, the pressure radiated everywhere else. This well-known procedure rests on hypotheses which are still not well mastered today, in particular with respect to boundary conditions. Because of this, no quantitative parameter can guarantee the reliability of the results obtained. At a time when industrialists must comply with strict norms, this question of guarantee is crucial. In the case of the acoustic radiation of an object such as a vehicle wheel, subjected to a vibratory stimulus, a holographic antenna placed beside the wheel observes only the front side and its rim while the rear side and the thickness of the tyre remain invisible. The invisible vibratory area manifests itself through information obtained partly from the complementary part of the source plane i.e., the plane containing the front of the wheel but without the front surface itself. Numerical simulations (with the help of the BIEM) in the unbounded 3D space show how the effect on the invisible area can be described by an impedance relation, thus resulting in a problem in the half-3D unbounded space. Usually, Neumann or Dirichlet boundary conditions are used on the complementary source plane. What are the consequences of mixed boundary conditions both on the hologram pressure and on the vibratory velocity identified? It will be shown that these boundary conditions modify the hologram pressure significantly and, thus, the reconstruction of the source velocity. This is, in fact, the starting point of the geometrical interpretation of nearfield holography, which originates from the field of active noise control.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p464.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p153" class="affilation"></a>Modified General Transfer Matrix Method for Linear Rotor Bearing Systems</h2>
<h3>B. B. Maharathi, R. R. Dash, T. Rout</h3>
<p class="affilation">Department of Mechanical Engineering, IGIT, Sarang, 769 146, Dhenkanal, Orissa, India</p>
<p><b>ABSTRACT</b><br>
A modified general transfer matrix method is developed for the steady state response analysis of linear flexible rotor-bearing systems in the frequency domain with fixed matrix size. In this paper, the modifications of the transfer matrix method based on Timoshenko Beam Theory are derived from the concept of continuous systems instead of the conventional lumped system concept and the paper tries to extend the transfer matrix method to fit a synchronous elliptical orbit and a non-synchronous multi-lobed whirling orbit. To demonstrate the applicability of this method, a three-disk rotor-bearing system is used as a physical model in the numerical analysis.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p153.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p684" class="affilation"></a>Noise and Vibration of Positive Displacement Compressors - A Review</h2>
<h3>Malcolm J. Crocker</h3>
<p class="affilation">Department of Mechanical Engineering, Auburn University, 270 Ross Hall, Auburn University, AL 36849-5341, USA</p>
<p><b>ABSTRACT</b><br>
Compressors are used widely throughout the world in household appliances, air-conditioning systems, vehicles and industry. It is clear that reducing noise and vibration is important in these applications. Various compressors are used for different applications and there are a large number of quite different designs. The compressor design adopted for each application depends upon several factors, including the gas or working fluid which must be compressed, and the discharge pressure and flow rates that need to be achieved. There are two basic types of compressor: 1) positive displacement compressors including reciprocating piston, and rotary types, and 2) dynamic compressors including axial and centrifugal types. This paper will discusses noise and vibration sources in positive displacement compressors and various approaches that have been used to reduce the noise generated. In addition some case histories of compressor noise reduction are be reviewed.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p684.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p641" class="affilation"></a>Noise Reduction of a Reciprocating Compressor by Adding a Resonator in Suction Path of Refrigerant</h2>
<h3>Yogesh V. Birari, Mayur M. Nadgouda</h3>
<p class="affilation">Product Engineering Department, Emerson Climate Technologies (India) Limited, Karad, MS, 415110, India</p>
<p><b>ABSTRACT</b><br>
The hermetically sealed reciprocating compressor used for air conditioning applications predominantly possesses four noise sources viz. motor, impact of reed (due to suction gas pulsations), mounting vibrations and discharge gas pulsations. The interaction of air-borne noise (by the flow of refrigerant inside compressor) and structure-borne noise (by the components of reciprocating mechanism) becomes cause of concern if a resonance condition is reached. This paper deals with noise reduction of a compressor by suppressing the airborne noise. A resonator structure is added in the suction path of compressor. The resonator adds desired values of lumped inertance and capacitance to the whole acoustic domain of compressor. The frequency at which this resonator will generate maximum transmission loss is dependent on its geometrical features. The sound spectrum of the compressor in 1/3<sup>rd</sup> Octave band is studied and on this basis the geometrical features of resonator are decided. The location of resonator is decided based on manufacturing considerations. The negative volume of resonator (the cavity inside resonator) is solved in Sysnoise. The transmission loss through the resonator is calculated over a range of frequency. A bench test of resonator prototype is conducted to establish a relation between the theoretical calculations and physical testing. The whole compressor domain (negative volume of refrigerant passage) is solved in Sysnoise. The transmission loss properties of the compressor with resonator and without resonator are compared. It is observed that the compressor with resonator gives higher transmission loss at the frequency of interest. The pressure drop of the refrigerant across the suction path is calculated in Fluent. The difference of pressure drop is insignificant in both the cases which indicate the compressor’s performance will not be affected. The compressor is built and tested for sound power level. 3 dBA of absolute SPL reduction is seen after testing four samples.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p641.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p516" class="affilation"></a>Stiffeners Effect on Sound Transmission Through a Thin Plate Excited by a Turbulent Boundary Layer (Corcos Model) - Comparison with a Diffuse Sound Field</h2>
<h3>Pascale Neple (1), Julien Manera (2), Nathalie Pellegrin (1), Jean-Pierre Coyette (2)</h3>
<p class="affilation">(1) AIRBUS, Acoustics and Environment Department, 316 Route de Bayonne 31060 Toulouse Cedex 09, France (2) Free Field Technologies S. A., Rue Emile Francqui 1, B-1435 Mont Saint-Guibert, Belgium</p>
<p><b>ABSTRACT</b><br>
In the context of understanding and predicting airborne sound transmission through aircraft structures, the main objectives of this work are to study the stiffeners effect on a thin plate under a turbulent boundary layer excitation (Corcos model) and to compare this effect to the one on a plate excited by a diffuse field. A numerical simulation using FEM software ACTRAN© has been carried out on a thin plate stiffened by frames and stringers, having its critical frequency equal to 7000 Hz. Both excitation fields are modelled as distributed weakly stationary random process. For the diffuse sound field, the classical spatial correlation function sin(kr)/kr is used, and the Transmission Loss TL is computed. For the turbulent boundary layer excitation, the Corcos model is used, and an equivalent Insertion Loss IL is determined. For both excitation fields, for the stiffened and unstiffened plate, TL and IL were obtained and compared in the 100 Hz - 2200 Hz range. For the turbulent boundary layer excitation the aerodynamic coincidence frequency is equal to 1700 Hz. The main results are the following: - for both excitation fields, the stiffened plate TL and IL are lower compared to the unstiffened ones in the 200 Hz - 1500 Hz range; - the differences between the stiffened and unstiffened structures depend on the excitation field both in levels and trends, thus the transmission mechanisms differ. Further investigation is compulsory to determine the most sensitive parameters for sound transmission through stiffened structures under turbulent boundary layer excitation.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p516.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p395" class="affilation"></a>Sound Reduction by Using Acoustic Resonators for Payload Fairing of Small Launch Vehicle</h2>
<h3>Sang-Hyeon Seo, Ho-Kyeong Jeong, Soon-Hong Park, Young-Soon Jang, Yeong-Moo Yi, Gwang-Rae Cho</h3>
<p class="affilation">Korea Aerospace Research Institute (KARI), 45 Eoeun-dong, Yuseong-Gu, Daejoen, 305-333, Korea</p>
<p><b>ABSTRACT</b><br>
To protect a satellite and electronic equipment from the acoustic loads generated by rocket propulsion system, many launch vehicle use acoustic blankets. Most high frequency region of the acoustic loads is reduced by nose fairing skins and acoustic blankets, but the low frequency region is not. In order to control low frequency acoustic mode, we designed an array resonator panel which was made of composite materials. Acoustic resonator has non linear characteristics in high-amplitude sound. This paper shows the absorption coefficient measurement result of resonators and sound reduction by using resonators in the payload fairing.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p395.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p679" class="affilation"></a>A Survey on the Control of Environmental Noise Ingress into Residential Apartment Buildings</h2>
<h3>Gayle Greer (1), Matthew Stead (2)</h3>
<p class="affilation">(1) Bassett Acoustics, Level 11, 44 Market Street, Sydney, NSW 2000, Australia (2) Bassett Acoustics, Level 6, 100 Pirie Street, Adelaide, SA 5000, Australia</p>
<p><b>ABSTRACT</b><br>
The urban consolidation of cities has been supported by most Australian State and Territory governments for a number of years in order to make the best use of existing infrastructure. Consequently, new residential developments are being located in areas of relatively high ambient noise levels. The ingress of high levels of environmental noise into homes can cause annoyance, speech, sleep and task interference and arguably, health effects. Additionally, in order for a sustainable community to be created, people must want to live within the built environment and its surrounds. Bassett Acoustics has been involved in the preparation of a scoping study report on environmental noise and the built environment in Australia. The objectives of the study were to determine if environmental noise ingress into Class 2 & 3 residential buildings within inner city and suburban areas is currently a significant problem and if so, how the problem would be best addressed. A number of options are available including consumer and industry education programmes, guideline documents, industry self-regulation or government regulation. This paper summarises the findings of the study.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p679.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p132" class="affilation"></a>The Acoustic Characterization of the Urban Territory with Continuous Cycle Producing Settlements</h2>
<h3>Massimo Coppi, Stefano Grignaffini</h3>
<p class="affilation">Technical Physics Department, University of Rome “La Sapienza”, Rome, 00184-Via Eudossiana, 18, Italy</p>
<p><b>ABSTRACT</b><br>
A method for the acoustic characterization of the territory with sound sources deriving from transportation infrastructures and from stable sources such as the producing settlements is being illustrated. Such a method allows for the identification of the main sound sources that act on the territory, in relation to the global present level, characterizing each source in connection with the effective acoustic ‘weight’ of the same.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p132.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p484" class="affilation"></a>Analysis and Evaluation of Environmental Noise Conditions in Two Different Areas in Mexico City</h2>
<h3>Miriam German González (1), Fernando Greene Castillo (2), Arturo O. Santillán (3)</h3>
<p class="affilation">(1) Program in Urbanism, Universidad Nacional Autónoma de México (UNAM), Mexico (2) School of Architecture, Universidad Nacional, Autónoma de México (UNAM), Mexico (3) Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México (UNAM), Mexico</p>
<p><b>ABSTRACT</b><br>
Mexico City, part of one of the world’s most crowded metropolitan areas with a population estimated at approximately 19 million, has major problems of noise pollution. However, existing data on these problems is unfortunately limited. An urban noise survey carried out in two different areas in Mexico City is presented. Two sites limited by different street typologies were chosen: site A, with an area of approximately 176 hectares, is located in the northern part of the city’s centre; site B comprises an area of about 440 hectares in the south of the city. Both places have their own identities, which are shown through their buildings and open public spaces of significant cultural importance. The sites were chosen because they have large volumes of road traffic, and open public spaces with intense human activities. The main objectives of this study has been: 1) to carry out measurements to evaluate urban noise levels from road traffic and leisure activities in open public spaces; 2) to determine if these levels exceed recommended values; and, 3) to compare noise levels of two different places in Mexico City. Measurement of main indexes for noise pollution (L<sub>Aeq</sub>, L<sub>10</sub>, L<sub>50</sub>, L<sub>90</sub>) and data from traffic flow and composition were acquired in randomly selected sites along streets and inside squares. The results have revealed that: a) environmental noise levels due to road traffic are significantly higher than the guideline values suggested by the World Health Organization and the Organization for Economic Cooperation and Development to protect public health and welfare; b) average sound levels correlated with traffic flow conditions, coincide with those of other authors; and c) environmental noise conditions in the two areas show a certain degree of spatial and temporal variation resulting primarily from the traffic flow and the multiple human activities.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p484.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p773" class="affilation"></a>On Annoying Sounds Generated as Byproducts of ‘Good Intentions’</h2>
<h3>Ricardo E. Musafir</h3>
<p class="affilation">Mechanical Engineering Department/COPPE and Dept. of Water Resources and Environmental Engineering/EP, Universidade Federal do Rio de Janeiro, C.P. 68503, RJ, 21945-970, Brazil</p>
<p><b>ABSTRACT</b><br>
This paper focus on the noise generated by the enormous amount of devices which, in our modern world, emit some sound in order to announce that something has happened, will happen, has been done, or, instead, in which unnecessary noise is generated by lack of a good electronic project. The need of acoustic consciousness in designers, as well as in the population in general - people frequently buy objects without even noticing the quality of the sound they make - is emphasized, as the only means or counteracting the growing wave of alarms of all type which, by their huge number, end up acting more as sources of noise pollution than anything else. The situation in Rio de Janeiro, Brazil, where some situations have led to lawsuits, is discussed, the presentation being illustrated by a number of video examples.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p773.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p493" class="affilation"></a>Management of Environmental Noise - Cracow Example</h2>
<h3>Wojciech Ciesielka, Andrzej Gołaś</h3>
<p class="affilation">Department of Mechanics and Vibroacoustics, The University of Science and Technology (AGH), Al. Mickiewicza 30, 30-059 Cracow, Poland</p>
<p><b>ABSTRACT</b><br>
The article shows an acoustic climate control system on the example of the City of Cracow. Information layers made in the SoundPlan, INM application, MapInfo and GRASS software are the system core. These layers show maps, which characterise noise emitted from individual sources (traffic-related noise - road, railway and air, and industrial and communal noise), and maps of areas exposed to noise and areas with exceeded acceptable values. The layers have been made pursuant to valid legal acts. Designed and built acoustic climate monitoring system and results of round-the-clock measurements carried out in order to assess an acoustic climate in Cracow conurbation were presented in the second part of this article. Among other things, the designed and completed monitoring system has been used for the purpose of railway and road acoustic climate round-the-clock monitoring. The system consisted of: an acoustic monitoring station, measuring system for weather conditions, GPS device, and audio and video signal recording device. The results of testing so obtained have served to build databases for the rail and road traffic for the Capital-Royal City of Cracow. The results of this report constitute a separate module in the form of information layers of the acoustic climate management system for the Capital-Royal City of Cracow, but due to their universal character, they may also be used for building management systems in other cities, agglomerations, municipalities, etc. The spatial information system technology (GIS) was used to create the system. Two application programs were designed and developed, which allow for work in public data communications networks and locally, independently of hardware platform and operating system. In future, the designed and systematically developed system for city acoustic climate management will become an integral element of city management system. It will allow for very convenient and extremely quick making of decisions related to acoustic climate.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p493.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p392" class="affilation"></a>Quiet City - A European Project to Support Cities in Noise Mitigation</h2>
<h3>Wolfgang Probst, Markus Petz</h3>
<p class="affilation">ACCON GmbH and DataKustik GmbH, D-86926 Greifenberg, Germany</p>
<p><b>ABSTRACT</b><br>
With the EU-Project “QUIET CITY” a broad approach has been undertaken to tackle environmental noise in European cities. Basis are the 3-dimensional virtual city models that are used to produce large scale noise maps keeping all parameter dependencies and traffic influences. Taking into account effect-annoyance relations, scoring techniques have been developed and these are used to find the hot spots where many people are unacceptably affected. A catalogue of mitigation measures has been developed that can be used by administrations and consultants to derive well adapted noise reduction programmes. Alternatively discussed packages are implemented in the 3D-city models, the noise maps are recalculated and based on the Noise Scoring System the solutions are ranked. The described techniques have been tested and are demonstrated with real projects, e. g. Augsburg, Stuttgart, Stockholm and some others.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p392.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p347" class="affilation"></a>Brake Noise in Practice</h2>
<h3>Antti Papinniemi, Daniel Stanef, Stephen Moore, Said Hamdi</h3>
<p class="affilation">PBR Australia Pty Ltd, 264 East Boundary Rd, Bentleigh East, Vic 3165, Australia</p>
<p><b>ABSTRACT</b><br>
Squeal in disc brake systems is an on-going concern for the automotive industry. Development of countermeasures for noise problems represents a large portion of the development cycle in terms of both time and cost. In addition, brake squeal represents a significant source of customer dissatisfaction and warranty cost. In this paper, an overview of brake noise development will be presented by way of a case study. Through rigorous testing and analysis it was determined that a noise problem could be countered by changing component dynamic behaviour, implemented through metallurgical changes, in combination with geometry modification at a key component interface. The final noise performance of the brake system was found to be a dramatic improvement compared to early testing, and well within the specification required by the vehicle manufacturer. The vehicle has since gone on to perform well in production without noise concerns arising in the field.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p347.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p211" class="affilation"></a>Disc Brake Squeal: Progress and Challenges</h2>
<h3>Antti Papinniemi (1,2), Joseph C.S. Lai (1), Jiye Zhao (2)</h3>
<p class="affilation">(1) Acoustics and Vibration Unit, School of Aerospace, Civil and Mechanical Engineering, The University of New South Wales at Australian Defence Force Academy, Canberra, ACT 2600, Australia (2) PBR Australia Pty Ltd, 264 East Boundary Rd, Bentleigh East, Vic 3165, Australia</p>
<p><b>ABSTRACT</b><br>
Brake squeal noise has been an ongoing concern with automotive brake systems since their inception. It is generated by the vibration of an unstable vibration mode of the brake system, usually with the brake rotor acting as a loudspeaker. The squeal noise that is of concern usually falls into a frequency range from 1 to 16 kHz. Although there is often not any degradation in the braking performance, most customers tend to interpret brake squeal noise as indicative of a defective brake. Furthermore, with improvements made in interior noise and comfort levels in vehicles, brake squeal noise has become an increasing source of customer dissatisfaction and is a major contributor to warranty cost. Research into predicting and controlling brake squeal has been conducted since the 1930s and despite significant research efforts in the past 2 decades, brake squeal still remains a challenging problem that is begging for a better understanding of its generation mechanisms and better methodologies for countermeasures other than empirical approaches. Brake squeal is a transient phenomenon and is highly dependent on geometries of brake components, complex interface conditions between components and material properties that are functions of both temperature and pressure. In this paper, recent developments in understanding and controlling brake squeal noise will be reviewed and challenges that remain to be met are discussed.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p211.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p192" class="affilation"></a>One-Dimensional Topology Optimization for Transmission Loss Maximization of Multi-Layered Acoustical Foams</h2>
<h3>Eun Il Kim (1), Joong Seok Lee (1), Yoon Young Kim (1), Jung Soo Kim (2), Yeon June Kang (2)</h3>
<p class="affilation">(1) National Creative Research Initiatives Multiscale Design Center, School of Mechanical and Aerospace Engineering, Seoul National University, Shinlim-Dong San 56-1, Kwanak-Gu, Seoul 151-742, Korea (2) Advanced Automotive Research Center, School of Mechanical and Aerospace Engineering, Seoul National University, Shinlim-Dong San 56-1, Kwanak-Gu, Seoul 151-742, Korea</p>
<p><b>ABSTRACT</b><br>
The topology optimization of one-dimensional multi-layered acoustical foams for transmission loss maximization is presented. The goal of this investigation is to find an optimal sequence and thickness of layers consisting of air gaps and certain poroelastic materials. Multi-layered acoustical foam sequences are optimized to maximize transmission loss for a target frequency or a range of frequencies. Though the one-dimensional multi-layered acoustical foam has been a popular subject in automobile and aircraft applications, the simultaneous design of sequencing and thickness has not been conducted yet. In this respect, the proposed design method can serve as a new optimal design method of multi-layered foams. For the calculation of transmission loss for a specific multi-layered foam appearing during optimization, the differential Biot equations are not solved directly, but an efficient transfer matrix approach is employed. The transfer matrix is a direct relationship between sound pressures and acoustic particle velocities on the incident and transmitted sides of a layer or a sequence of layers. The transfer matrix approach can significantly enhance computational efficiency of the topology optimization. By developing a unified model representing air gaps and poroelastic materials, the whole optimization process is performed with an efficient gradient-based optimizer. In the proposed model, the air layer is treated as a poroelastic material having limiting material properties. Several numerical case studies confirmed the effectiveness of the proposed design method for finding optimal multi-layer sequences.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p192.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p50" class="affilation"></a>Questionnaire-Based Survey on Drivers’ Noise and Vibration Discomfort</h2>
<h3>Mohd. Jailani Mohd. Nor, Baba Md Deros, Dian Darina Indah Daruis</h3>
<p class="affilation">Department of Mechanical and Materials Engineering, Faculty of Engineering, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia</p>
<p><b>ABSTRACT</b><br>
A questionnaire-based survey was conducted to gather information regarding driving discomfort of Malaysian passengers’ vehicle drivers. The discomfort factors investigated were noise and vibration in the vehicle both during idle and accelerating conditions. In the final survey, there were 63 subjects. It was found that 37% voted for engine noise during idle as compared to 32% for engine noise during accelerating. Men were found to experience less discomfort than women drivers in most of the driving conditions investigated. At the same time, age difference showed a different trend of response.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p50.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p51" class="affilation"></a>Identification of Vehicle Interior Noise Sources Using Vibro-Acoustic Spectral Analysis Method</h2>
<h3>Mohd. Jailani Mohd. Nor, Mohammad Hosseini Fouladi, Ahmad Kamal Ariffin</h3>
<p class="affilation">Department of Mechanical and Materials Engineering, Faculty of Engineering, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia</p>
<p><b>ABSTRACT</b><br>
Continuous exposure to sound emitted by road vehicles will have direct effect on the comfort and fitness of the drivers, especially during long distance travel. It is imperative that automotive manufacturers invest a lot of effort and money to improve and enhance the vibroacoustics performance of their product. The enhancement effort would be very difficult and time consuming if one relies only on ‘trial and error’ methods without prior knowledge about the sources itself. Complex interior noise inside the vehicle cabin originated from various sources and travel through many pathways. It is vital for the automotive engineers to identify the dominant noise sources from measurement data obtained inside the vehicles such as tyre noise, engine noise, exhaust noise and noise due to turbulence. In this paper, a multi-channel analyzer is utilised to measure and record vibro-acoustic signals. Computational algorithms are also employed to identify contribution of the various sources towards the measured signals. These achievements can be utilised to detect, control and optimise interior noise performance of road transport vehicles.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p51.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p593" class="affilation"></a>Evaluation of Enhancement of Sound Quality of Axle Gear Based on Artificial Neural Network</h2>
<h3>Tae-Gyu Kim, Sang Kwon Lee, Sung-Jong Kim</h3>
<p class="affilation">School of Mechanical and Manufacturing Engineering, Inha University, Inchon, 402-751, Korea</p>
<p><b>ABSTRACT</b><br>
There are various sounds in the car as much as cars have many mechanical parts. These sounds make various sound qualities. The international competition in car markets has continuously required the research about the sound quality of a car. The domestic carmakers have also invested a lot of money for the research and development of sound quality. Car axle plays an important role in a vehicle and its NVH development is also important. By this time, NVH development of car axle is mainly based on the reduction of sound pressure level (dBA), which cannot gives, the satisfaction to the customers in view of the sound quality of a vehicle. Therefore, in this project, a sound quality index evaluating the sound quality of axle noise based on human sensibility is developed and applied to the development of the sound quality of axle noise.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p593.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p532" class="affilation"></a>Integration of Sub-Systems on Vehicles</h2>
<h3>Vincent Martin (1), Saül Mapagha (2)</h3>
<p class="affilation">(1) Institut Jean Le Rond d’Alembert, CNRS/Paris VI, 2 place de la gare de Ceinture, 78210 St Cyr l’Ecole, France (2) Centre d’études vibro-acoustiques pour l’automobile, 2 rue joseph Fourier, 76800 Saint Etienne du Rouvray - France</p>
<p><b>ABSTRACT</b><br>
When a host structure is excited by a vibratory system, called sub-system, it also vibrates and may radiate an acoustic pressure. Presently, this subject originates from the car industry, but has in fact a far wider range of applications in other transport industries as well as in the field of musical instruments. The aim of the investigation is first to deduce the vibratory behaviour of the host structure from that of the sub-system observed on a test host structure which is often very rigid and for this reason called marble (or test bench). Second, what constraint should be satisfied on the marble, according to a given constraint on the host structure? And finally, in case the constraint on the test bench is not satisfied, what could be done to reach the goal? These three aspects are developed for harmonic linear vibrations. The first item is solved by an elementary analytical approach, the second rests on the transfer of mathematical norms, and the third is a problem of optimization for which a geometrical interpretation could provide ideas for the procedure to follow.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p532.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p190" class="affilation"></a>Characterization of Variable Material Properties by Nonlinear Acoustic Techniques</h2>
<h3>Arvi Ravasoo</h3>
<p class="affilation">Centre for Nonlinear Studies, Institute of Cybernetics at Tallinn University of Technology, Akadeemia, tee 21, 12618 Tallinn, Estonia</p>
<p><b>ABSTRACT</b><br>
The recent results on the development of the mathematical basis of nonlinear acoustic techniques for nondestructive testing (NDT) of inhomogeneously prestressed nonlinear elastic material, weakly inhomogeneous nonlinear elastic material and nonlinear viscoelastic material are presented. The one-dimensional problems of nonlinear propagation and interaction of longitudinal waves in inhomogeneous materials are solved analytically. The possibility to utilize the derived solutions in NDT is studied in detail in the case of sine-wave propagation. The idea is to extract, besides the wave velocity measurement data, information from nonlinear effects of wave propagation and interaction. The algorithms for four different NDT techniques are proposed.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p190.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p703" class="affilation"></a>Simplifications and Solutions of Diffraction Functions in Nonlinear Acoustic Parameter Measurement</h2>
<h3>Djilali Kourtiche, Laurent Alliès, Rachid Guelaz, Mustapha Nadi</h3>
<p class="affilation">LIEN, Nancy-Université, Faculté des sciences et techniques, BP 239, 54506 Vandoeuvre, France</p>
<p><b>ABSTRACT</b><br>
This paper presents an analytical formulation for correcting the diffraction associated to the second harmonic of an acoustic wave, more compact than that usually used. This new formulation, resulting from an approximation of the correction applied to fundamental, makes it possible to obtain simple solutions for the second harmonic of the average acoustic pressure, but sufficiently precise for measuring the parameter of nonlinearity B/A in a finite amplitude method. Comparison with other expressions requiring numerical integration, show the solutions are precise in the nearfield.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p703.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p725" class="affilation"></a>Modelling and Simulation of Ultrasound Non Linearities Measurement for Biological Mediums</h2>
<h3>Djilali Kourtiche, Rachid Guelaz, Mustapha Nadi</h3>
<p class="affilation">LIEN, Nancy-Université, Faculté des sciences et techniques BP 239, 54506 Vandoeuvre, France</p>
<p><b>ABSTRACT</b><br>
We present an implementation of the nonlinear propagation in an ultrasonic measurement modeling with VHDL-AMS-IEEE-1046-1999 language. The system is dedicated to nonlinear mediums characterization by a compared method measurement. Usual modelling of ultrasonic transducers are based on electrical analogy and are not simulated in the global measurement environment. The ultrasonic transducer modelling proposed is simulated with the nonlinear acoustic load and electronic excitation. The nonlinear B/A parameter is used to characterize medium with a comparative method. The measurement cell is composed of two piezoelectric ceramic transducers which are implemented with the Redwood’s electric scheme. The analyzed medium is placed between the transducers and modeled to take into account the nonlinear propagation with the B/A parameter. The usual transmission line model has been modified to take into account the nonlinear propagation for a one dimensional wave. Results obtained with simulation of mediums characterization with (blood, milk, liver and human fat tissue) showed good a modeling in agreement between modelling and experimental measurement, also a maximum error of about 12.5%.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p725.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p172" class="affilation"></a>A Center Manifold Algorithm for Nonlinear Dynamic Systems with Time-Delay and Parametric Excitation</h2>
<h3>Eric A. Butcher (1), Venkatesh Deshmukh (2), Ed Bueler (3)</h3>
<p class="affilation">(1) Department of Mechanical Engineering, New Mexico State University, Las Cruces, NM 88003, U.S.A. (2) Department of Mechanical Engineering, Villanova University, Villanova, PA 19085-1681, U.S.A. (3) Department of Mathematics and Statistics, University of Alaska Fairbanks, Fairbanks, AK 99775, U.S.A.</p>
<p><b>ABSTRACT</b><br>
A technique for center manifold reduction of nonlinear delay differential equations with time-periodic coefficients is presented. The DDEs considered here have at most cubic nonlinearities multiplied by a perturbation parameter. The periodic terms and matrices are not assumed to have predetermined norm bounds, thus making the method applicable to systems with strong parametric excitation. Perturbation expansion converts the nonlinear response problem into solutions of a series of non-homogenous linear ordinary differential equations with time periodic coefficients. One set of linear non-homogenous ODEs is solved for each power of the perturbation parameter. Each ODE is solved by a Chebyshev spectral collocation method. Thus we compute a finite approximation to the nonlinear infinite-dimensional map for the DDE. The accuracy of the method is demonstrated with a nonlinear delayed Mathieu equation, a milling model, and a single inverted pendulum with a periodic retarded follower force and nonlinear restoring force in which the amplitude of the limit cycle associated with a flip bifurcation is found analytically and compared to that obtained from direct numerical simulation.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p172.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p429" class="affilation"></a>Sometimes Digital Control Leads to Chaos</h2>
<h3>Gábor Csernák (1), Gábor Stépán (2)</h3>
<p class="affilation">(1) HAS-BUTE Research Group on Dynamics of Machines and Vehicles, H-1521 Budapest, Hungary (2) Budapest University of Technology and Economics, Department of Applied Mechanics, H-1521 Budapest, Hungary</p>
<p><b>ABSTRACT</b><br>
In the present paper, we introduce and analyse a mechanical system in which the digital implementation of a linear control loop may lead to chaotic behaviour. The amplitude of the evolving oscillations is usually very small, this is why these are called micro-chaotic vibrations. As a consequence of the digital effects, i.e., the sampling and the round-off error, the behaviour of the system can be described by a three dimensional piecewise linear map, the micro-chaos map. We examine a 2D version of the micro-chaos map and prove that the map is chaotic.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p429.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p64" class="affilation"></a>An Analytical Model for Drillstring Axial Vibration</h2>
<h3>Gholamreza Rashed (1), Rahmatolah Ghajar (2), Seyed Jelaladdin Hashemi (3)</h3>
<p class="affilation">(1) Faculty of Petroleum Engineering, Petroleum University of Technology, Ahwaz P. O. Box 63431, I. R. Iran (2) Mechanical Engineering Department, K. N. Toosi University, Tehran P. O. Box 16765-3381, I. R. Iran (3) Petroleum University of Technology and Islamic Azad University- Ahwaz Branch, Ahwaz P. O. Box 63431, I. R. Iran</p>
<p><b>ABSTRACT</b><br>
The axial vibrational states experienced by the active components of a drilling assembly such as that found in the oil or gas industry are discussed in the context of an analytical model. This paper is purposed by the need to understand the axial vibrational states that such a system can demonstrate in order to better control their constructive and destructive potential. The objective is to present more reliable analytical models of drillstring axial vibration. In the proposed model, the drillstring is modeled as an equivalent piecewise uniform bar and particular attention is given to boundary conditions, the excitation mechanism of a bit, the effect of mud viscosity, and the effect of tooljoints. Field experiments were performed in Ahwaz well (in the South of Iran). The results are used to validate the proposed model and to better understand drillstring axial vibration. The good agreement between the measured and predicted result give considerable confidence to the use of the analytical model developed.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p64.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p24" class="affilation"></a>Limit-Cycle Oscillation of Shape Memory Alloy Hybrid Composite Plates at Elevated Temperatures</h2>
<h3>Hesham Hamed Ibrahim (1), Mohammad Tawfik (2), Hani Mohammed Negm (3)</h3>
<p class="affilation">(1) National Authority for Remote Sensing and Space Sciences, Cairo, Egypt (2) Modeling and Simulation in Mechanics, German University in Cairo, Egypt (3) Aerospace Engineering Department, Faculty of Engineering, Cairo University, Egypt</p>
<p><b>ABSTRACT</b><br>
A traditional composite plate impregnated with pre-strained shape memory alloy (SMA) fibers and subject to combined thermal and aerodynamic loads is investigated, to demonstrate the effectiveness of using the SMA fiber embeddings in improving the dynamic response of composite plates. The problem investigated is the nonlinear flutter limit-cycle and chaotic oscillations at elevated temperatures. A nonlinear finite element model based on the first-order shear deformable plate theory is derived. von Karman strain displacement relations are utilized to account for geometric nonlinearity. Aerodynamic pressure is modeled using the quasi-steady first-order piston theory. The governing equations are obtained using the principle of virtual work based on thermal strain being a cumulative physical quantity. Newton-Raphson iteration is employed to obtain the dynamic response at each time step of the Newmark numerical integration scheme. A time domain method along with modal transformation is applied to numerically investigate periodic, non-periodic, and chaotic limitcycle oscillations. The results show that the amplitude of the limit-cycle oscillation is highly decreased by using SMA fiber embeddings.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p24.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p17" class="affilation"></a>Identifying Chaotic Dynamics in a Flying Vibratory System</h2>
<h3>Jin-Wei Liang (1), Shy-Leh Chen (2), Ching-Ming Yen (3)</h3>
<p class="affilation">(1) Dept. of Mech. Eng., Mingchi University of Technology, Taiwan (2) Dept. of Mech. Eng., National Chung-Cheng University, Taiwan (3) System Development Center, Chung-Shan Inst. of Science and Tech., Taiwan</p>
<p><b>ABSTRACT</b><br>
This paper determines whether chaotic dynamics exists in a flying vibratory system. Acceleration signals were measured at nine different locations or orientations of the flying object during a test flight. Steady-state acceleration data were extracted to reconstruct pseudo phase-space trajectories from which two dynamical indices including the correlation dimension and the maximum Lyapunov exponent are calculated. Although generally the correlation dimension depends on the embedding dimension, it is found that in three out of the nine-channel acceleration signals, the correlation dimension saturates when the embedding dimension reaches a critical value. The phenomenon indicates a possible existence of chaotic motion. The maximum Lyapunov exponents calculated for the same three-channel data are all positive which again implies the possible existence of chaos. To determine whether the experimental time series that demonstrate chaotic characteristics are in fact deterministic (rather than random noise), a sequence of two statistical tests is applied. Based on these tests, the possibility of those three-channel acceleration data being random noise is excluded.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p17.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p654" class="affilation"></a>Study on Mechanized Mathematics Modelling for 200 MW Turbo-Generator System</h2>
<h3>Li-guo Wang (1), Bo Fang (2), Fengming Li (2), Dianguo Xu (1), Wenhu Huang (2)</h3>
<p class="affilation">(1) Dept.of Electrical Eng., Harbin Institute of Technology, Harbin 150001, Heilongjiang Province, China (2) Dept.of Aerospace Eng.and Mech., Harbin Institute of Technology, Harbin 150001, Heilongjiang Province, China</p>
<p><b>ABSTRACT</b><br>
For 200 MW turbo-generator system, considering higher order and higher dimension of nonlinear differential equations governing the motion of its rotor-bearing system, the Mechanized Mathematics Method can be used as modelling and analyzing means of rotor-bearing system in order to obtain the analyzed solutions of the 200 MW turbo-generator system. When the order of the differential model has been reduced by fixed interface mode synthesis method, it may be transformed into an algebraic expression set by Wu Elimination Method (WEM). Then lower dimension algebraic equations included nonlinear oil force expressions are obtained, because of the nonlinear parts of oil force expressions can be remained after eliminating the linear coupling variable of node displacements of rotor-bearing system of 200 MW turbo-generator system. Differential Control Method (DCM) that is different to analyzed method and the classical numerical method was presented in this paper. According to proposed method the model of 200 MW turbo-generator system has been described and its node displacement response of system was analyzed and predicted. The analysis results based on proposed method stand with very good agreement with previous numerical calculate results.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p654.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p809" class="affilation"></a>Rectifications of Parametric Instability Due to Asymmetry of Rotating Shaft</h2>
<h3>Malik M. Nazeer, M. Suleman, A. F. Khan, S. W. Hussain, K. Ahmed</h3>
<p class="affilation">Institute of Rotor Dynamics, P.O. Box No. 905, Islamabad, Pakistan</p>
<p><b>ABSTRACT</b><br>
In this work, the asymmetric stiffness based parametric instability problem of rotating shaft system is analytically analyzed and its rectifications are presented. The term responsible for the problem in the governing equation is explored to find out the parameters having the problem elimination or minimization potential. Two such analytical findings have been practically implemented and the problem has successfully been rectified. Although both the strategies qualified, yet one of them has an edge over the other in implementation, risk elimination and qualitative-quantitative results. The two strategies attack the problem from two different visions, one pre and the other post problem symptoms observation. The post problem symptoms observation strategy has constraints and can be implemented only to the rotating shafts which had survived in the initial testing while the pre problem sensing approach is independent of any problem symptom, much easy in implementation and unlimited survival rate. Hence the last one, the preemptive measure is to be preferred over the post.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p809.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p89" class="affilation"></a>Theoretical Research Regarding Any Stability Theorems with Applications</h2>
<h3>Marcel Migdalovici, Daniela Baran</h3>
<p class="affilation">Institute of Solid Mechanics, 2INCAS Elie Carafoli, 115 C-tin Mille street, 2220 Iuliu Maniu street, Bucharest, Romania</p>
<p><b>ABSTRACT</b><br>
The research is focuses on the theoretical study of the stability in sense of Lyapunov for evolution of the dynamical systems that depend of parameters. Is proven an original theorem of separation between the stable and unstable zones, in the plane of chosen principal parameters. In the paper is related, using this results, an original method for identification, in the plane of principal parameters of the mathematical model of the dynamical system, the stabilities and instabilities regions of the dynamical system motion. We analyze also a lot of theorems, as the Floquet stability theorem, about the motion stability for the dynamical systems described by differential equation systems with periodical coefficients. The results are applied to study the motion stability of the couple pantograph-contact wire of the electrical locomotive. The parameters of the system consist of two concentrated masses, the bending stiffness, the horizontal tension, the viscous damping and the mass per unit length of the wire, the other damping coefficients and stiffness elements of the system and any constant speed specified in the model. We study the stabilities and instabilities regions of the dynamical system motion using these parameters and our original method of identification of stability zones, in the plane of principal parameters of the mathematical model of the dynamical system pantograph-contact wire.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p89.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p101" class="affilation"></a>Free Vibrations of the Systems of Rigid Bodies Coupled by Elastic Bars</h2>
<h3>Marina Pandrea, Nicolae-Doru Stănescu, Nicolae Pandrea</h3>
<p class="affilation">Department of Applied Mechanics, University of Piteşti, Piteşti, 110227, Romania</p>
<p><b>ABSTRACT</b><br>
It is well known that by using the plückerian coordinates the force at one end of the bar is given by the product between the rigidity matrix and the difference between the displacements at the ends of the bar. With the aid of this relation are obtained the differential equations of the vibrations of a rigid bodies system coupled by elastic bars, the expressions of the rigidity matrix and of the displacements of the rigid bodies being written in the general reference frame. In the final part of the paper is presented an application for the vibrations of a system consisted of two plane shells connected each one with a bar to the fixed system and coupled one to the other by a bar.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p101.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p62" class="affilation"></a>Behaviour of Ultrasonic Wave Velocities in Materials Under Elastic Thermo Mechanical Effect</h2>
<h3>Med.O. Si-Chaib (1), H. Djelouah (2), A. Nour (1)</h3>
<p class="affilation">(1) Faculté des Sciences de l’Ingénieur, Laboratoire Dynamique des Moteurs et Vibroacoustique, Université de Boumerdès, 35000, Algerie (2) Faculté de Physique, Laboratoire de Physique des Ultrasons, USTHB, BP, 32, El-Alia, Algerie</p>
<p><b>ABSTRACT</b><br>
This study deals with the propagation of longitudinal and shear ultrasonic waves which are transmitted in isotropic thermo elastic materials supposed initially in a stress free state. Ultrasonic waves propagating in a material depend on some elastic properties of the propagation medium such as volume mass and induced deformation resulting from applied mechanical or thermal stresses. They also depend on the nature of propagated longitudinal or shear waves and in this last case they also depend on the polarization direction of the wave. For homogeneous and isotropic materials, no linear mechanics provides acoustoelastic expressions of velocities as function of second and third elastic constants and applied stresses. Submitting a sample to a small temperature change, we study the behaviour of ultrasonic waves in presence of thermomechanical stresses applied according to considered directions of propagation, polarization and loading. A numerical simulation of elastic thermo mechanical effect has been applied to two usual materials in C 33 steel and in AlMg3 aluminium alloy. This method allows simulating the behaviour of ultrasonic wave velocities under elastic thermo mechanical effects.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p62.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p171" class="affilation"></a>Static Output Feedback Control for Non-Linear Flutter and Limit Cycle Oscillation</h2>
<h3>Morteza Dardel, Firooz Bakhtiari-Nejad</h3>
<p class="affilation">AmirKabir University of Technology, Hafez Ave. Tehran, Iran</p>
<p><b>ABSTRACT</b><br>
Non-linear flutter and limit cycle oscillations (LCOs) control of a non-linear wing are considered here. For this purpose, at first, a new formulation of static output feedback control is developed, and then an optimal solution for determining gains is presented. The optimal solution obtained from solving combined Lyapunov and Riccati equation. The designed controller applied for suppression of LCOs of low aspect ratio rectangular wings in low subsonic flow. This non-linear wing model has double bending in both chord-wise and span-wise directions (Von Karman plate theory). For aerodynamic modelling, a vortex lattice method is used. Results show, with this simple controller, we can effectively suppress limit cycle oscillation and extend flutter boundary.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p171.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p70" class="affilation"></a>Phase Change Analysis of Planar and Nonplanar Vibration in One-to-One Resonance of Nonlinear Cantilever Beam</h2>
<h3>Myoung-Gu Kim, Chongdu Cho, Chang-Boo Kim, Heung-Shik Lee</h3>
<p class="affilation">Department of Mechanical Engineering, Inha University, 253 Yonghyen-Dong, Nam-Ku, Incheon City, 402-751, Republic of Korea</p>
<p><b>ABSTRACT</b><br>
A symmetric long slender cantilever beam with nonlinearities shows many nonlinear dynamic phenomena. One-to-one resonance of the beam is well shown in the nonlinear vibration. Among the nonlinear factors of the flexible symmetric cantilever beam, nonlinear inertia term and nonlinear spring term are the most important. When base harmonic excitation is applied to the beam, planar vibration and nonplanar vibration occur in the beam due to one-to-one resonance. When one-to-one resonance occurs, the planar vibration is different from the nonlinear one. When one-to-one resonance is developed in the first and the second mode of the nonlinear beam, the beam has different amplitudes and phase values. The phase value changes according to the excitation frequency. Thus, the phase change and the phase difference between the planar vibration and the nonlinear vibration are investigated both theoretically and experimentally when the symmetric nonlinear beam shows one-to-one resonance.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p70.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p99" class="affilation"></a>A Non-Linear Model for Studying the Motion of a Human Body</h2>
<h3>Nicolae-Doru Stănescu (1), Marina Pandrea (1), Dinel Popa (1), Sorin Ilie (2), Ştefan-Lucian Tabacu (2)</h3>
<p class="affilation">(1) Department of Applied Mechanics, University of Piteşti, Piteşti, 110227, Romania (2) Department of Automotive, University of Piteşti, Piteşti, 110227, Romania</p>
<p><b>ABSTRACT</b><br>
In our paper we developed a non-linear model for studying the motions of a human body. For our model we obtained the equations of motion using the Newton’s equations. We also treated a few aspects concerning the stability of the equilibrium and motion.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p99.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p100" class="affilation"></a>Non-Linear Aspects of Human Body’s Motion in Car Crash</h2>
<h3>Nicolae-Doru Stănescu (1), Marina Pandrea (1), Dinel Popa (1), Sorin Ilie (2), Ştefan-Lucian Tabacu (2)</h3>
<p class="affilation">(1) Department of Applied Mechanics, University of Piteşti, Piteşti, 110227, Romania (2) Department of Automotive, University of Piteşti, Piteşti, 110227, Romania</p>
<p><b>ABSTRACT</b><br>
Using the model developed by the authors in a previous paper, this article purposes a study of the human body’s motion in car crashes. We realized numerical simulations for the main parameters of the human body system using realistic values. The most important diagrams were captured and discussed. Finally we presented a few conclusions.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p100.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p262" class="affilation"></a>Bearing Profile and Misalignment Effects on the Vibration Behaviour of Rotating Machinery</h2>
<h3>Ningsheng Feng, Eric Hahn</h3>
<p class="affilation">School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney, NSW 2052, Australia</p>
<p><b>ABSTRACT</b><br>
The vibration behaviour (eg. unbalance response, stability) of rotating machinery consisting of flexible rotors supported by hydrodynamic or fluid film bearings is significantly affected by the dynamic characteristics of the bearings. These characteristics depend on bearing parameters such as length, diameter, nominal clearance, rotor speed and oil viscosity, as well as the bearing reaction load (which depends on the relative transverse alignment of the bearings in statically indeterminate systems). Hence, various bearing profiles are used in practice and care is taken in setting the relative bearing positions during installation in order to improve dynamic performance, prolong service life and enhance productivity. There are two types of bearing clearance profiles used in practice: the multi-lobe type consisting of two or more lobes (pads) with defined pad curvature centres which need not coincide with the bearing centre; or the wave type with variable curvatures normally defined by some functions. Investigated here theoretically is the effect of the first type of profile (including axial groove, elliptic, 3 lobe, and 2 or 3 pad offset bearings) and the effect of lateral misalignment on the vibration behaviour of the machinery. For any particular profile, the dynamic characteristics of the bearings are obtained via a numerical solution of the Reynolds equation, a partial differential equation describing the pressure distribution in the fluid film. Sample results show how different bearing clearance profiles and different degrees of lateral misalignment affect the natural frequencies, stability thresholds and unbalance response of simple statically indeterminate rotor bearing systems (systems with more than two bearings). Among the bearings investigated, under the assumed conditions of the numerical examples, different bearing profiles are shown to have different effects on the stable system performance due to bearing misalignment.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p262.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p138" class="affilation"></a>Non Linear Response of Beams Using Finite Element Method with Symplectic Integration Scheme</h2>
<h3>R. R. Dash, T. Rout, B. B. Maharathi</h3>
<p class="affilation">Department of Mechanical Engineering, Indira Gandhi Institute of Technology, Sarang, Orissa, India</p>
<p><b>ABSTRACT</b><br>
The beam finite element matrices are formed with the assumption that it is subjected to large deflection with small strain and rotation. The finite element equations are represented in Hamiltonian form and are solved by the appropriate symplectic integration scheme. The induced axial forces are not averaged and the first second and third order stiffness matrices are formed to incorporate the effect of axial force. All conservative laws are observed during the numerical integration. The response of the beam is studied for free and forced vibration with un-damping cases.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p138.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p319" class="affilation"></a>Numerical Simulation of Nonlinear Sound Wave Propagation Using CIP Method</h2>
<h3>Takao Tsuchiya (1), Kan Okubo (2), Nobunao Takeuchi (2)</h3>
<p class="affilation">(1) Department of Information Systems Design, Doshisha University, 1-3 Miyakodani, Tatara, Kyotanabe-shi, Kyoto 610-0321, Japan (2) Department of Electrical Information Systems, Akita Prefectural University, 84-4 Ebinokuchi, Tsuchiya, Yurihonjyo-shi, Akita 015-0055, Japan</p>
<p><b>ABSTRACT</b><br>
In this paper, numerical simulation of nonlinear sound wave propagation in time domain is performed by Constrained Interpolation Profile (CIP) method. CIP is a novel numerical scheme which was recently proposed by Yabe. It is one kind of method of characteristics (MOC) and is a high accuracy numerical scheme in which numerical dispersion errors are hardly caused. To achieve high accuracy, not only the acoustic field values on the grid point but also their spatial derivatives are used in the scheme. It is suitable for analysis of nonlinear wave propagation including weak shock formation because the rapid pressure change such as shock front easily causes numerical dispersion error in the conventional numerical scheme. Some numerical demonstrations are made for the one-dimensional nonlinear sound propagation in air. The results are compared with the conventional FDTD method and the analytical solutions.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p319.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p40" class="affilation"></a>Therapeutic High Intensity Focused Ultrasound Fields (HIFU): Acoustic Characterization And Nonlinear Mechanics Of Heating</h2>
<h3>Vera A. Khokhlova (1,2), Michael R. Bailey (1), Michael S. Canney (1), Olga V. Bessonova (2), Lawrence A. Crum (2)</h3>
<p class="affilation">(1) Center for Industrial and Medical Ultrasound, Applied Physics Laboratory, University of Washington, 1013 NE 40<sup>th</sup> Street, Seattle, WA 98105, USA (2) Dept. of Acoustics, Faculty of Physics, Moscow State University, Moscow 119992, Russia</p>
<p><b>ABSTRACT</b><br>
Nonlinear acoustic waves have been widely employed in various areas of modern science and technology. Medical ultrasound, that includes both therapeutic and diagnostic techniques, is one of the most exciting examples. In therapy, high intensity focused ultrasound (HIFU) waves provides the ability to localize the deposition of acoustic energy noninvasively within the body, which can cause tissue necrosis (for tumor treatment) and stop bleeding (acoustic hemostasis). At HIFU intensity levels of 10000 - 30000 W/cm<sup>2</sup> the combined effects of nonlinearity and diffraction results in formation of shock waveforms and corresponding distortion of spatial distributions of various acoustic parameters, responsible for different therapeutic mechanisms. Super focusing effect occurs for the peak positive pressure and heat deposition, which makes acoustic measurements and modeling difficult. Formation of shock waves due to nonlinear propagation, violent ultrasound induced cavitation, and corresponding nonlinear enhancement of thermal and mechanical effects of ultrasound on tissue are strongly pronounced at the high intensity levels used in modern therapies. Heating may also result in formation of boiling vapor bubbles that grow much larger than the cavitation bubbles and alter lesion dynamics. In this paper nonlinear HIFU fields and the relevant role of nonlinear phenomena in HIFU induced bioeffects were investigated experimentally and numerically in a gel phantom. The KZK equation was employed for acoustic field characterization under experimental conditions. A fiber optic probe hydrophone, passive cavitation detection system, optical imaging were used to measure HIFU shock waveforms, cavitation thresholds, and boiling. Elevated static pressure was applied to suppress bubbles thus isolating the pure effect of acoustic nonlinearity in enhanced heating. Strongly distorted shock waves of up to 80 MPa peak positive and 15 MPa peak negative pressure were measured and modeled at focus in water and in the gel. It was observed that lesion distortion and migration was due to boiling detected in as little as 40 ms within the center of the lesion in agreement with nonlinear acoustic simulations. These data indicate that acoustic nonlinearity and the boiling play a significant role earlier in HIFU treatments than previously anticipated.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p40.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p231" class="affilation"></a>The Analytical Calculations of the Parameters of the Fluctuations of the Ballistic Missiles</h2>
<h3>Vladimir Gordon, Svetlana Ovsyannikova, Yury Stepanov</h3>
<p class="affilation">State Technical University of Oryol, 29, Naugorskoje shosse, 302020, Oryol, Russia</p>
<p><b>ABSTRACT</b><br>
The analytical calculations of natural frequencies and forms of the longitudinal and flexural vibrations of the heterogeneous rods, which simulate ballistic missiles, are proposed. These objects are characteristic by significant drops in the distribution of stiffness and density along the length. The indicated dynamical characteristics knowledge is necessary for the design of the system of control and evaluation of the strength of articles.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p231.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p84" class="affilation"></a>Gauge Invariance Approach to Acoustic Fields</h2>
<h3>W. S. Gan</h3>
<p class="affilation">Acoustical Technologies Singapore Pte. Ltd., 209-210, Innovation Centre, NTU, 16 Nanyang Drive, Singapore 637722, Singapore</p>
<p><b>ABSTRACT</b><br>
We extend the gauge invariance property of the Maxwell’s equations to the acoustic field equations. We use the analogy of the sound velocity as equivalent to the magnetic field and the acoustic stress field as equivalent to the electric field. We apply to sound propagation in solids and negative refraction. For sound propagation in solids, we use the equation of motion and the strain-displacement relation and express the velocity field and the stress field in terms of the vector potential and the scalar potential. We solve the inhomogeneous wave equation for these potentials and obtain the velocity field and the stress field in terms of these potentials. This gives a more rigorous solution than that from the Christoffel equation. Gauge invariance has symmetry property. We obtain the gauge form for the acoustic scalar potential and the vector potential and demonstrate their invariant property. We also show that the inhomogeneous wave equation in terms of the vector potential and the scalar potential possesses symmetry property. We also show the symmetry property of the acoustic field equation. We also derive the acoustic Lorentz condition from the equation of continuity. For the application of gauge invariance to negative refraction , we first show that the acoustic field equations also possess left hand and right hand symmetry and this gives rise to negative refraction. This is a different approach from that of Veselago who derives negative refraction from the negative permittivity and negative permeability. Here we extend negative refraction to anisotropic materials. In anisotropic materials, the compliance and stiffness possess rotational symmetry. When rotating in the clockwise direction, it gives rise to lefthanded phenomenon such as negative refraction. When rotating in the anticlockwise direction, it gives rise to the righthanded phenomenon such as positive refraction. Due to symmetry, both the righthanded phenomenon and the lefthanded phenomenon satisfy the acoustic field equations. The stress field, the velocity field and the acoustic Poynting vector together form a righthanded triplet or a lefthanded triplet depending on the direction of energy flow or the direction of the Poynting vector. According to parity conservation, acoustic law at the deepest level, there is no differentiation of righthanded and lefthanded treatment. The performance of an object and that of its mirror image will satisfy the same law of physics. The negative refraction in fact is a mirror image of the positive refraction.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p84.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p85" class="affilation"></a>Vector Theory of Ultrasonic Imaging</h2>
<h3>W. S. Gan</h3>
<p class="affilation">Acoustical Technologies Singapore Pte. Ltd., 209-210, Innovation Centre, NTU, 16 Nanyang Drive, Singapore 637722, Singapore</p>
<p><b>ABSTRACT</b><br>
So far works on ultrasonic diffraction imaging are based on scalar theory of sound wave. This is not correct as sound has vector nature. When sound propagates in fluids it can be approximated as a scalar wave as there is no polarization. But when sound propagates in solids, its vector nature has to be considered as polarization occurs and transverse wave as well as longitudinal wave will appear. Vector theory is especially needed when the obstacle size is smaller than the wavelength. We use the Smythe-Kirchhoff approach for the vector theory of diffraction.Comparing the result with the scalar Kirchhoff approximation, we find that both contain the same diffraction distribution factor and the same dependence on wave number. But the scalar result has no azimuthal dependence whereas the vector expression does. The azimuthal dependence variation comes from the polarization properties of the field and must be absent in a scalar approximation. We use the analogy of the sound velocity as equivalent to the magnetic field and the acoustic stress field as equivalent to the electric field to convert our result from the electromagnetic case to the acoustic case. We then derive the image formation theory based on the vector diffraction theory. We use the angular spectrum approach. We found the existence of the components of the angular spectrum known as evanescent waves. These waves are more properly treated in a vectorial approach. We then discuss the effect of polarization on acoustical imaging.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p85.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p618" class="affilation"></a>Generalisation of Veselago’s Negative Refraction Theory Using Symmetries</h2>
<h3>W. S. Gan</h3>
<p class="affilation">Acoustical Technologies Singapore Pte. Ltd., 209-210, Innovation Centre, NTU, 16 Nanyang Drive, Singapore 637722, Singapore</p>
<p><b>ABSTRACT</b><br>
In this paper, we generalize Veselago’s negative refraction theory to anisotropic solids using symmetry. Veselago’s theory is applicable only to electromagnetic wave and is limited only to isoptropic solids using linear dispersion. Most solids are anisotropic and we also extend his theory to acoustic waves. Veselago’s theory depends on negative permeability and negative permittivity to obtain negative refractive index. We derive the expression for the transmission/refraction coefficient for acoustic wave at the interface between two anisotropic materials in terms of the angle of refraction in the second medium. We find that this expression is invariant whether we use the positive angle of refraction or the negative angle of refraction. This shows reflection/mirror symmetry and the existence of negative refraction. We next apply righthanded and lefthanded symmetry to polarization and refraction. In acoustic fields theory and electromagnetic theory there is righthand or clockwise polarization and lefthand or anticlockwise polarization. The direction of polarization is in turn related to the angle of refraction. For instance transverse electric polarization will give rise to negative refraction and transverse magnetic polarization will give rise to positive refraction. This shows there is a relation between the direction of polarization and the angle of refraction. Next we look at the possibility of obtaining negative refraction even with materials with positive permeability and positive permittivity. This will ease the difficulty of fabrication of materials yielding negative refraction and widen the scope of application of such materials.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p618.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p240" class="affilation"></a>Analysis of Golf Ball Spin Mechanism at Impact by FEM</h2>
<h3>Woo-Jin Roh, Chong-Won Lee</h3>
<p class="affilation">Center for Noise and Vibration Control (NOVIC), Dept. of mechanical engineering, KAIST, 373-1 Guseong-dong, Yuseong-gu, Daejeon, Republic of Korea</p>
<p><b>ABSTRACT</b><br>
It is important to improve the initial launch conditions of golf ball at impact between golf club and ball to get a long flight distance. The flight distance is greatly influenced by the initial launch conditions such as ball speed, launch angle and back spin rate. It is also important to analyze the mechanism of ball spin to improve the initial conditions of golf ball. Back spin rate is created by the contact time and force. Previous studies showed that the contact force is determined as the resultant force of the reaction forces normal and tangential to the club face at the contact point. The normal force causes the compression and restitution of ball, and the tangential force creates the spin. Especially, the tangential force is known to take either positive or negative values as the ball rolls and slides along the club face during impact. Although the positive and negative tangential forces are known to create and reduce the back spin rate, respectively, the mechanism of ball spin creation has not yet been discussed in detail in the literature. In this paper, the influence of the contact force between golf club and ball is investigated to analyze the mechanism of impact. For this purpose, the contact force and the time at impact between golf club head and ball are computed using finite element method (FEM) and compared with previous results. In addition, we investigate the impact phenomenon between golf club head and ball by FEM and clarify the mechanism of ball spin creation accurately, particularly focusing on the effect of negative tangential force on ball spin rate.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p240.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p649" class="affilation"></a>Design of a Hula-Hoop Energy-Harvest Device Paper </h2>
<h3>Y. C. Kung, Cheng-Kuo Sung, Paul C.-P. Chao</h3>
<p class="affilation">Department of Power Mechanical Engineering, National Tsing Hua University, 101, Sec. 2, Kuang-Fu Rd, Hsinchu, Taiwan 30013, Republic of China</p>
<p><b>ABSTRACT</b><br>
This paper proposes a design of the energy-harvest device that mimics the motion characteristics of the hula hoop, which is commonly regarded as the circular oscillations where a ring undergoes around a moving human body. In the hula-hoop energy-harvest device, there are a main mass and a free-moving mass. The former that performs reciprocating motion is considered as the human body while the latter that rotates around the main mass simulates the ring. The mechanical device is then integrated with coils, magnets, and electric circuits to form a portable energy-harvest device. Unlike the assumption of harmonic-force input of our previous study, we consider the external excitation is resulted from the human hand motion in this study, which features non-periodic external force input. Therefore, we have experimentally investigated and quantified the motion pattern of the human hand under ordinary living conditions. Then, a thorough dynamic analysis is performed to understand the relation between the varied system parameters and the chance of occurrence of hula-hoop motion. The governing nonlinear equations are first formulated based upon Lagrange’s equation, which is followed by searching of domains of attraction and corresponding stability analysis. The numerical simulation is also performed by using direct integration method to verify the aforementioned qualitative analysis. On the basis of the obtained results, the design guidelines for determining the suitable system parameters and initial conditions to ensure the occurrence of hula-hoop motions are distilled.</p>
<hr>
<h2><a name="p303" class="affilation"></a>Effects of Landing Gear Nonlinearities on Ground Resonance of Helicopter</h2>
<h3>Yoon-kyu Lee, Kwang-joon Kim</h3>
<p class="affilation">Center for Noise and Vibration Control, Department of Mechanical Engineering, KAIST, Science Town, Daejeon 305-701, South Korea</p>
<p><b>ABSTRACT</b><br>
One of key targets in helicopter design is to be free from ground-resonance, which may occur when lead-lag frequency of rotor is coupled with natural frequencies of rotor-fuselage-landing gear system. Typical analytical approach to this problem is based on simplified linear modeling for the landing gear. In practice, however, the landing gear has nonlinear characteristics not only when touching down but also when operating on ground, depending on stroke, velocity and friction of oleo-pneumatic shock absorber in the landing gear. In this study, a method is proposed to predict the vibration severity and unstable range of rotor speed, by including the nonlinear characteristics in the landing gear. Then, effects of landing gear nonlinearities will be discussed.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p303.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p175" class="affilation"></a>A Study on Response Analysis of Pneumatic Vibration Isolation Table Loaded by Transient Movements of Carriage on it</h2>
<h3>Yun-ho Shin, Jong-oh Sun, Kwang-joon Kim</h3>
<p class="affilation">Department of Mechanical Engineering, KAIST, 373-1 Science Town, Daejeon-shi, South Korea</p>
<p><b>ABSTRACT</b><br>
As environmental vibration requirements on precision equipments get more stringent, use of pneumatic vibration isolators becomes more crucial and, hence, their dynamic performance needs to be further improved. Dynamic behavior of those pneumatic vibration isolation tables is very important to both manufacturer and customer as performance specifications. Together with conventional transmissibility, transient response characteristics are another critical performance index especially when movements of components, e.g., xy-stage, of the precision equipments are very dynamic. In this paper, analysis on transient response of a pneumatic vibration isolation table loaded by a mass moving on it is presented. This is a conventional dynamics problem on a rigid body with 6 degree of freedom and a mass on it with another degree of freedom. How to obtain transient responses of the isolation table is described when the movements of the mass are prescribed relative to the table.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p175.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p660" class="affilation"></a>Passive Noise Control of a Burner-Combustor System of a Turbo-Fan Engine</h2>
<h3>Ayman El-Badawy (1), Wael El-Arna’outy (2)</h3>
<p class="affilation">(1) Department of Engineering Mechanics, The German University in Cairo, New Cairo City, Al-Tagamoa Al-Khames, Egypt (2) Department of Mechanical Engineering, Al-Azhar University, Nasr City, Cairo, Egypt</p>
<p><b>ABSTRACT</b><br>
The application of the Herschel-Quincke (HQ) tube concept as a noise reduction device is employed to reduce the noise of an industrial burner-combustor test rig. A computational technique is developed to design the HQ tube dimensions to control the sound field in such system. Transmission loss predictions from the analytical model are shown to correlate well with experimental data acquired from an extended impedance tube setup, as well as the real test rig. In addition, the frequencies at which maximum attenuation will occur are determined.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p660.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p298" class="affilation"></a>Nodalization of Isolator for Floating Floor Design</h2>
<h3>C. K. Hui, C. F. Ng</h3>
<p class="affilation">Department of Civil and Structural Engineering, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR.</p>
<p><b>ABSTRACT</b><br>
In this paper, a new design concept of an isolated honeycomb floor with a special arrangement of isolators is proposed to improve the vibration isolation performance of conventional lightweight cement floor panels in the frequency range of 120 Hz to 600 Hz. The symmetric bending resonance frequencies and mode shapes of a honeycomb floor panel were identified by a shaker test. The effects on vibration isolation of isolator position were then investigated using experimental modal analysis. The analysis suggests that to ensure the optimum vibration isolation performance the isolators must be placed at the nodal points of the symmetric bending modes of the floor panel. The proposed floating floor design achieved a vibration reduction of 20 dB to 30 dB in the frequency range of 120 Hz to 600 Hz. In addition, the proposed floor was found to have a 20-dB lower vibration level at the first bending resonance frequency than the conventional design with isolators that are placed at the edges.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p298.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p299" class="affilation"></a>The Effects of Local Modes on Vibration Reduction of Building Isolation</h2>
<h3>C. K. Hui (1), Y. Y. Lee (2), C. F. Ng (1)</h3>
<p class="affilation">(1) Department of Civil and Structural Engineering, The Hong Kong Polytechnic University, Kowloon, Hong Kong (2) Department of Building and Construction, City University of Hong Kong, Kowloon Tong, Kowloon, Hong Kong</p>
<p><b>ABSTRACT</b><br>
This paper investigates the vibration isolation performance of isolated box structures. Isolated box inside building is a one of the building isolation designs. Some experimental methods are developed to analyze the effects of bending mode of the box structure on vibration isolation efficiency. The vibration reduction performance of an isolated box inside building is found to be degraded by bending resonances of the isolated box. In the design of building isolation, apart from the conventional design of natural frequency of rigid body vibration, the control of local mode resonance frequencies is found to be also important.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p299.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p14" class="affilation"></a>Theoretical and Experimental Results of the Transmission Loss of a Plate with Discrete Masses Attached</h2>
<h3>Carl Howard</h3>
<p class="affilation">School of Mechanical Engineering, University of Adelaide, SA 5005, Australia</p>
<p><b>ABSTRACT</b><br>
A mathematical model is developed to calculate the transmission loss of a simply-supported plate with an array of masses attached. Experimental tests were conducted and compared with the theoretical predictions and showed that there was good agreement. The results showed that the transmission loss of the plate can be improved by the addition of the masses, greater than that which would be predicted from the ‘mass-law’ model.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p14.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p520" class="affilation"></a>Design Analysis of a Rubber Mount System for a Push-Type Centrifuge</h2>
<h3>Carl Nel</h3>
<p class="affilation">School of Mechanical Engineering, North-West University, Potchefstroom, South Africa</p>
<p><b>ABSTRACT</b><br>
The lack of balance, which occurs in all rotating machines, could cause troublesome vibration if the attachments to the foundation of the machine are unsuitable. This is particularly true for centrifuges, where uneven loading of the basket, for example, due to temporary irregularities in the feed or layers of salt sediment on the basket, may lead to particularly bad balancing. The aim of this investigation was to evaluate the use of rubber mounts and to predict feasible mount stiffness coefficients to be used. These mounts have to produce good vibration isolation to protect the supporting building from dynamic forces transmitted, but must also limit the static and dynamic mount displacements to allow acceptable motion of the centrifuge assembly. It was therefore necessary to use a six-degree of freedom mathematical model, implemented in computer programs to compute these static and dynamic mount displacements and mount forces, for 2 possible designs. An objective function as a measure of vibration transmitted, was also used. In addition, the mount system natural frequencies were also computed, to prevent resonance with the normal basket angular speed and also the forced frequency of the axial pusher mechanism.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p520.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p325" class="affilation"></a>The Dynamic Characteristics of SMA Helical Spring in Axial Vibratory Motion</h2>
<h3>Chun-Ying Lee, Chia-Wei Hsu</h3>
<p class="affilation">Department of Mechanical and Automation Engineering, Da-Yeh University, Changhua 515, Taiwan</p>
<p><b>ABSTRACT</b><br>
The helical spring is capable of providing the flexibility in more than one axis and the shape memory alloy (SMA) has the tuneable mechanical property controlled by the temperature change and stress, etc. Therefore, the use of SMA helical spring in the vibration platform with controllability in multi-directions could find application in the many aspects. For example, the suspension spring for an optical disk drive. In this study, the axial vibratory characteristics of the helical spring made of SMA are investigated. The shear strain of the SMA spring wire is assumed as a linear distribution and is proportional to the radius from the centre of the wire, when the spring is subjected to axial loading. However, the SMA undergoes phase transformation between martensite and austenite at different stress and temperature. Therefore, the mechanical behavior of the spring changes with respect to the amplitude of vibration and the controlled temperature. The constitutive relation of the SMA proposed by Brinson is adopted and the hysteresis loop due to the martensitic transformation is considered. An approach of equivalent strain energy is employed to derive the apparent stiffness of the spring in different vibratory amplitudes and temperatures, with the consideration of different Young’s moduli for different phases. The energy enclosed by the hysteresis loop is accounted for the study of the damping capacity of the spring. The experimental setups for quasi-static deflection test and sprung-mass vibration test have been constructed, respectively. Both the simulated results and experimental measurements show the decrement in spring constant with respect to the deflection amplitude. In the meanwhile, the damping property increases with the raise in deflection amplitude. It is shown the formulation can be applied in the design of the SMA helical spring.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p325.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p405" class="affilation"></a>Noise Transmission Control of Double Partition Windows Using T-Shaped Acoustic Resonators</h2>
<h3>Deyu Li, Ganghua Yu, Li Cheng</h3>
<p class="affilation">Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hung Home, Kowloon, Hong Kong, SAR of China</p>
<p><b>ABSTRACT</b><br>
This paper presents theoretical and experimental noise transmission analyses on a double-partition window with structurally integrated T-shaped acoustic resonators. The study aims at providing a new and practical solution for the building and construction industry to tackle the ever-increasing noise pollution problems for residential areas locating near the airport and high traffic areas. Conventionally, grid-stiffened windows and double-partition windows are used to reduce the noise transmission into rooms. However, the use of grid-stiffeners embedded to glass panels will sacrifice window’s vision quality and double-partition windows usually loose the noise insulation efficiency in the low-frequency range. Although classical Hemlholtz resonators may be used to improve the noise control performance of double-partition windows, this treatment is however not practical in such small enclosures due to the bubble-like profile of the Helmholtz resonator. The double-partition windows proposed in this paper incorporate long T-shaped acoustic resonators. The large aspect ratio of the long T-shaped acoustic resonator makes it possible to integrate the resonator into the sash of the windows, which relaxes the space requirement in implementation. A mathematical model describing structural and acoustic interaction between the glass panels, air cavity, and resonators is presented. Based on the model, the optimal location of the resonators is determined considering multiple cavity modes in addition to the targeted mode. Series of numerical simulations are conducted to illustrate the control of a specific resonance peak. The theoretical development provides insight into the noise transmission mechanism, leading to a helpful design tool for generating solutions to reduce the magnitude of noise transmission at cavity resonances, which currently still involve an effort of trial and error. Experimental measurements are also carried out, which are compared with the theoretical predictions.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p405.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p144" class="affilation"></a>Development and Application of High Damping Alloys for Noise and Vibration Control</h2>
<h3>Fuxing Yin</h3>
<p class="affilation">Innovative Materials Engineering Laboratory, National Institute for Materials Science, Tsukuba, 305-0047, Japan</p>
<p><b>ABSTRACT</b><br>
High damping alloys are finding more and more applications in several industrial fields as a passive technique in vibration and acoustic attenuation. Manganese-copper based alloys are the most potential high damping alloys. In order to improve the damping stability and workability of the traditional Manganese-copper based alloys, M2052 high damping alloy has been developed, which shows the superior damping behavior and the high mechanical properties. In the present work, the properties and the application trials of the alloy are introduced.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p144.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p406" class="affilation"></a>Internal Resistance Optimization of a Helmholtz Resonator in Noise Control of Small Enclosures</h2>
<h3>Ganghua Yu, Deyu Li, Li Cheng</h3>
<p class="affilation">Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hung Home, Kowloon, Hong Kong, SAR of China</p>
<p><b>ABSTRACT</b><br>
This paper examines the influence of the internal resistance of a Helmholtz resonator on the noise control in a small enclosure. The absorptive process mainly occurring within the neck of a Helmholtz resonator provides the resonator with a damping (internal resistance) property, which directly dissipates the input energy in the resonator. The remaining non-dissipated energy is re-radiated back to the enclosure, such forming an effective secondary sound source, and resulting in acoustic interaction with the primary source. If the internal resistance of the resonator is low, the acoustic interaction between the enclosure and the resonator sharply splits the targeted resonance peak of the enclosure into two parts, and the peak response is significantly attenuated within a very narrow frequency band. By appropriately increasing the internal resistance at the resonance of the resonator, the working bandwidth can be enlarged at the expense of sacrificing the control performance due to the decreased amplitude. However, if the resistance is over-increased, the strength of volume velocity out of the resonator aperture becomes too low; compromising the effective acoustic interaction with the enclosure and resulting in insignificant control at the targeted resonance peak. In this paper, a mathematical model describing the acoustic interaction of a resonator and a small enclosure is presented. An analytical solution is obtained on the pressure field inside the enclosure and the radiation of the resonator. Based on the analytical solutions, an energy reduction index describing the strength of acoustic interaction in the enclosure with a resonator is defined. Series of numerical simulations are conducted to illustrate the influence of the internal resistance on the energy reduction and on the dissipated and re-radiated energy. Finally, the optimal internal resistance is obtained. Experimental results using one resonator are also carried out and compared with simulation results.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p406.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p755" class="affilation"></a>Design of Sydney Olympic Stadium for Mitigation of Crowd-Induced Vibration</h2>
<h3>Graham Brown, Peter Erdmanis, Ross Emslie, David Hanson</h3>
<p class="affilation">Structural Dynamics Group, Sinclair Knight Merz, St. Leonards, Sydney, NSW 2065, Australia</p>
<p><b>ABSTRACT</b><br>
Increasingly, crowd-induced vibration is seen as an important issue in the design of assembly occupancies, especially large stadia, which are used for pop concerts, involving rhythmic activity, as well as sporting events. This paper presents an overview of an investigation undertaken by Sinclair Knight Merz into the response of the Sydney Olympic Stadium due to crowd-induced vibration. The first part of the investigation involved the construction of a finite element model of the stadium which was subjected to dynamic loading to simulate the likely response of the structure to concert loads. The vibration responses were evaluated in terms of design specifications based on the Canadian Building Code. The results of these simulations, and a review of crowd-induced vibration in the literature, were used to develop the original stadium design to reduce predicted vibration responses. The design approach, together with the final design and its implementation are described in the paper. The second part of the investigation involved the subsequent testing of the structure during a concert performance. Accelerations were recorded at ten locations on the structure over the duration of the concert and the structure was shown to meet the performance requirements for crowd-induced vibration.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p755.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p244" class="affilation"></a>Theoretical and Experimental Investigation on Power Flow of a Raft Vibration Isolation System</h2>
<h3>Guangming Wu (1), Qiang Wang (2), Rongying Shen (1)</h3>
<p class="affilation">(1) State Key Laboratory of Mechanical System and Vibration , Shanghai Jiao Tong University, Shanghai 200030, P.R.China (2) Shanghai Marine Equipment Research Institute, Shanghai 200031, P.R.China</p>
<p><b>ABSTRACT</b><br>
The raft vibration isolation system, one of the most effective isolation systems, is widely adopted to isolate vibration and reduce radiation sound of engines and auxiliary machines on ships. In this paper, the modeling of the raft vibration isolation system has been paid much more attention on considering the flexibility of the raft and the foundation. The general equations of motion for the raft vibration isolation system have been successfully derived by means of a new substructure method. The power flow from the machine to the raft and further to the foundation has been studied theoretically and experimentally. An experimental rig of the raft isolation system, including elastic raft and non-rigid foundation, has been set up. The power flow through the experimental model has been successfully measured. The comparison between the theoretical predicted power flow and the experimental ones has been completed and analyzed. The agreement of the power flow results demonstrates the correctness of the new modeling theory and power flow theory of the raft vibration isolation system.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p244.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p241" class="affilation"></a>Transmission Path Characterization for Passive Vibration Control</h2>
<h3>Per Sjövall, Thomas Abrahamsson</h3>
<p class="affilation">Department of Applied Mechanics/CHARMEC, Division of Dynamics, Chalmers University of Technology, SE-41296 Gothenburg, Sweden</p>
<p><b>ABSTRACT</b><br>
Analysis, prediction and reduction of vibration transmission in built-up structures are addressed. The sensibility to vibrations varies spatially within a structure, due to issues as passenger comfort and/or the localization of certain sensitive components or instruments. Traditionally, vibration transmission has been analyzed adopting transfer path analysis (TPA). The contribution to the vibration amplitude or sound pressure level in some particular locations from each transfer path is quantified using the transfer path operational forces and the frequency response function (FRF) of the receiving structure. TPA considering energy based quantities such as supplied power has gained popularity as it provides more stable path contributions and ranking of dominant paths. The supplied power is associated with the far-field contribution to the response, which may be used as an approximation of the complete response in the mid and high frequency range. For low frequencies however, the near-field contribution, which is associated with the reactive power, will be significant. Hence, in that case the supplied power is not well suited to characterize vibration transmission. Furthermore, it is not obvious how to modify a dominant transfer path so that the vibration response or the supplied power attenuates. Generally, the system must be considered as a whole in order to avoid sub-optimization. Examples that stress the statements above are given and an alternative tool for transfer path ranking, suitable for structural optimization is proposed. A scalar vibration exposure function is defined and the transfer paths are ranked based on its gradient with respect to physical parameters associated with each path.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p241.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p23" class="affilation"></a>Particle Damping for Vibration and Noise Reduction</h2>
<h3>Zhiwei Xu (1), Michael Yu Wang (2), Tianning Chen (3)</h3>
<p class="affilation">(1) The Aeronautical Science Key Laboratory for Smart Materials and Structures, Nanjing University of Aeronautics and Astronautics, Nanjing, China (2) Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, Hong Kong, China (3) College of Mechanical Engineering, Xi’an Jiaotong University, Xi’an, China</p>
<p><b>ABSTRACT</b><br>
The purpose of this paper is to report an application of particle damping technique for noise reduction of a desk-top industrial machine. We applied the particle damping technique to a desk-top banknotes processing machine as a task to substantially reduce its noise (by 6 dB(A)) to the level of a standard requirement when it is in operation in an office environment.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p23.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p454" class="affilation"></a>Reassignment Vector Field for Time-Frequency Segmentation</h2>
<h3>Fabien Millioz, Nadine Martin</h3>
<p class="affilation">Gipsa-lab INPG-CNRS, 961 rue de la Houille Blanche, Domaine universitaire - BP 46, 38402 Saint Martin d’Hères cedex - France</p>
<p><b>ABSTRACT</b><br>
In this paper, we propose to use the phase information of the Short Time Fourier Transform (STFT) to improve a time-frequency segmentation based on the statistical features of the STFT, and proposed by the authors in 2006. If the resolution of the STFT is too low, close components may be segmented in a single pattern. The idea is to add phase information provided by the reassignment principle in order to determine if there are more than one component in a pattern instead of two. Reassignment, originally proposed by Kodera et al. in 1976, is a non-linear method which creates a new time-frequency representation by moving the spectrogram values away from their computation place. Reassignment focuses energy components by moving each time-frequency location to its group delay and instantaneous frequency, that represent more accurately the component energy. The obtained reassignment vector field associated to a given spectrogram describes how time-frequency locations are reassigned. We propose to use the reassignment vector field not to modify the time-frequency representation, but to give information on the signal structure. We compute local reassignment vectors on patterns segmented by the method mentioned above. Given that spectrogram tends to spread the time-frequency patterns, whereas reassignment method moves back energy to a pattern’s point, reassignment vectors aim at the pattern. That leads to a pattern’s boundary information, which is used to determine how many components are embedded in a single segmented pattern. Moreover, this information describes the boundaries of frequency modulations as well as wide band signal, and extends the use of the reassignment principle to wide band signals. This principle is finally applied to the shaft’s vibrations of a three phase AC induction engine, in order to separate the different harmonics embedded in a single pattern.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p454.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p491" class="affilation"></a>Novel Transform for Vibro-Acoustical Recognition of Bilinear Systems</h2>
<h3>L. Gelman, I. Petrunin, C. Thompson</h3>
<p class="affilation">School of Engineering, Cranfield University, Cranfield, MK 43 0AL, UK</p>
<p><b>ABSTRACT</b><br>
It is proposed and investigated a novel transform for vibro-acoustical recognition of bilinear mechanical systems. It is shown that the proposed transform is more effective for bilinearity recognition than classical technique.</p>
<hr>
<h2><a name="p541" class="affilation"></a>Separating Gear and Bearing Signals for Bearing Fault Detection</h2>
<h3>Wenyi Wang</h3>
<p class="affilation">Air Vehicles Division, Defence Science and Technology Organisation (DSTO), Fishermans Bend, Melbourne, VIC 3207, Australia</p>
<p><b>ABSTRACT</b><br>
This paper presents a technique for separating vibration signals generated by gears and rolling element bearings in rotating machinery for the detection of bearing faults. One of the most commonly used methods for detection of rolling element bearing fault is envelope analysis of the vibration signal, which often relies on the identification of structural resonances. However, envelope analysis can often be difficult when the measured vibration signal is dominated by gear mesh harmonics. The technique proposed in this paper uses a resampling process synchronised with respect to the shaft rotation and a multi-band filtering process that removes all shaft synchronous vibration components. The resulting non-synchronous signal is expected to be dominated by bearing vibration, to which an envelope analysis across the whole bandwidth should be sufficient for the extraction of bearing fault characteristic information. An application of this technique to test data shows that it is effective in detecting a small seeded raceway fault. In comparison to the commonly used envelope technique, the proposed method does not rely on the identification of prominent resonance peaks that are only excited by the faulty bearing vibration. The proposed technique should be particularly useful in cases where bearing excited resonances are not easily identifiable or they are corrupted by stronger gear mesh harmonics. It should be straightforward to implement the technique into any existing fault detection system that has a shaft speed signal.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p541.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p722" class="affilation"></a>Sound Absorption of a Vibrating Plate with Piezoelectric Materials and Passive Electrical Networks</h2>
<h3>Daoqing Chang, Bilong Liu, Xiaodong Li, Jing Tian</h3>
<p class="affilation">Institute of Acoustics, Chinese Academy of Sciences, Beijing 100080 China</p>
<p><b>ABSTRACT</b><br>
The possibility of sound absorbing by a vibrating plate with piezoelectric material shunted with passive electrical circuit is investigated. Using Lagrange’s approach, a governing equation for the flexural vibration of the plate attached with piezoelectric wafer shunted with RL circuits is derived. As a consequence, the effective mechanical impedance for the corresponding plate is obtained. A measurement based on an impedance tube is also conducted to gauge the influence of the shunting RL circuits on the sound absorption. Good agreements achieved when the measured sound absorption coefficients are compared with the calculations from the mathematics model established in this paper.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p722.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p326" class="affilation"></a>Vibration Suppression Performances of Power Harvesting Systems Using Piezoelectric Transducers</h2>
<h3>Kimihiko Nakano (1), Tsuyoshi Arinaga (2)</h3>
<p class="affilation">(1) Institute of Industrial Science, the University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505 Japan (2) Graduate School of Science and Engineering, Yamaguchi University, 2-16-1 Tokiwadai, Ube 755-8611, Japan</p>
<p><b>ABSTRACT</b><br>
Vibration suppression and power harvesting utilizing the piezoelectric shunt technique are analysed using equations that consider the effect of the dynamical properties of the transducer on the vibration of the structure. Numerical calculations show that the optimal conditions for suppression and harvesting do not agree; therefore, we need consider a trade-off between them before installing piezoelectric transducers.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p326.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p528" class="affilation"></a>Some Results on Control of Sound Radiation Using Shunt Piezoelectric Materials</h2>
<h3>Stanislaw J. Pietrzko, Qibo Mao</h3>
<p class="affilation">Empa - Swiss Federal Laboratories for Materials Testing and Research, Ueberlandstrasse 129, CH-8600 Duebendorf, Switzerland</p>
<p><b>ABSTRACT</b><br>
In this paper, several shunt piezoelectric damping techniques will be considered. Different types of shunt circuits, employed in the passive damping arrangement, will be analyzed and compared from a theoretical perspective. By using the impedance method, the piezoelectric shunt circuit can be seen as additional frequency-dependence damping of the system. By minimization of the sound power of the structure, the optimal parameters for shunt circuits can be obtained. Also, the switch law for pulse-switching circuit will be discussed based on the energy dissipation technique. Numerical simulations will be performed for each of these shunts techniques focusing on minimizing of radiated sound power from a plate. Experimental results will be presented using a RL series/parallel shunt circuit, a RL-C parallel shunt circuit and pulse-switching circuit. The results show that the vibration of a structure and noise radiation can be reduced significantly by using these shunt circuits.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p528.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p456" class="affilation"></a>Comparative Analysis of Retrofit Windows for Noise Control at a Hotel</h2>
<h3>Chad Himmel</h3>
<p class="affilation">JEAcoustics 1705 W Koenig Ln, Austin, TX 78756-1206, USA</p>
<p><b>ABSTRACT</b><br>
Guest rooms in a historic landmark luxury hotel suffered excessive environmental mechanical equipment noise intrusion through windows. Measurements of outdoor-indoor sound transmission loss have been carried out to compare the performance of four retrofit sound control window fixtures with performance of existing fixtures. The hotel originally opened in 1924 and reopened in 2000, after a multi-million dollar renovation in which original window fixtures were replaced. Several guest rooms overlook the roof of the hotel’s adjacent banquet and meetings wing, with rooftop mechanical equipment that includes air-cooled chillers, air handlers, exhaust fans, and cooling tower. Hotel management desired to reduce mechanical noise in guest rooms, and some window fixtures were again replaced or augmented with various retrofit sound control glazing fixtures. Sound transmission loss measurements using outdoor amplified broadband noise source and, separately, mechanical equipment noise sources were conducted on one existing, single-pane guest room window type and four multi-pane sound control glazing fixtures to compare effectiveness. Analysed window types included single-pane, double-pane, and triple-pane systems, and glazing types included laminated glass and plate glass. No specific noise reduction criterion was used, but analyses were conducted to determine which glazing fixture’s noise reduction spectrum best matched the tonal noise spectra of the existing mechanical equipment. Noise reduction spectra were also analysed with respect to ASTM (OITC and STC) and ISO (Rw) curve fitting techniques. Noise reduction with amplified broadband noise source was compared to noise reduction with mechanical equipment noise and vibration sources to evaluate possible contributions from equipment vibration. This paper presents photographs and details of the existing and retrofit window conditions with tabular and graphical results from measurement of outdoor-indoor sound transmission through windows and existing interior ambient conditions.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p456.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p687" class="affilation"></a>Lightweight Timber Floors: a Simple Guide to Low-Frequency Impact Insulation</h2>
<h3>Grant Emms (1), Warwick Banks (2), Ken McGunnigle (3)</h3>
<p class="affilation">(1) Scion, 49 Sala St., Private Bag, 3020, Rotorua 3046, New Zealand (2) Carter Holt Harvey, Private Bag 92106, Auckland 1020, New Zealand (3) Prendos Ltd., P.O.Box 33-700, Takapuna, Auckland 0740, New Zealand</p>
<p><b>ABSTRACT</b><br>
One of the major problems with the impact insulation of lightweight floors is poor insulation of low-frequency impact sounds. This problem is often expressed by occupants as audible `thud’ and ‘boom’ noises. A recent Australasian project looked at ways to improve the low-frequency impact insulation of timber floors. The particular emphasis was to produce floor designs which can be easily built in New Zealand and Australia. It is a difficult problem with many confounding factors involved. The project produced a number of theoretical and experimental results. In this paper we look at the translation of these results into design recommendations which hopefully can be used directly by building designers.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p687.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p346" class="affilation"></a>Design Chart of Sound Insulation for Multiple Panels</h2>
<h3>Hyun-Ju Kang, Bong-Ki Kim, Jae-Seung Kim, Sang-Ryul Kim</h3>
<p class="affilation">Acoustic Lab. Korea Institute of Machinery and Materials</p>
<p><b>ABSTRACT</b><br>
The present paper is aimed at a design method in a form of design chart that can be used for sound insulation of sandwich panels. The design chart is based on two independent variables, Young’s modulus of core and thickness of skin plate, resulting in tune of dilatational frequency and then STC(Sound transmission Class). Based on this chart, we can draw a conclusion that lowering Young’s modulus of core material is very important in order to increase STC. It is experimentally well verified that adoption of air gap to lower Young’s modulus of core gives to enhance more than 10 dB in STC value.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p346.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p597" class="affilation"></a>Studies on Insertion Loss Experiment of Cracked Plates</h2>
<h3>Jiang Lin</h3>
<p class="affilation">Department of Naval Architecture, Dalian University of Technology, LiaoNing, DaLian116024, China</p>
<p><b>ABSTRACT</b><br>
The correlation acoustic scattering experiment of 13 freedom plates of different cracks and a intact freedom plate have been investigated in this paper by using advanced acoustical experiment system. Insertion loss is used as diagnose index and experimental show that insertion loss is sensitive to the crack position and it will be decreasing with the length, the depth and the number of cracks. Insertion loss can be considered as an easy new diagnose index for non-destructive detection.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p597.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p367" class="affilation"></a>Subjective Evaluation of Heavy-Weight Impact Sounds Generated by an Impact Ball</h2>
<h3>Jin Yong Jeon, Pyoung Jik Lee, Jae Ho Kim</h3>
<p class="affilation">School of Architectural Engineering, Hanyang University, Seoul 133-791, Korea</p>
<p><b>ABSTRACT</b><br>
Subjective evaluations of heavy-weight impact sounds generated by an impact ball on reinforced concrete floors in apartment buildings were conducted in order to investigate the effect of loudness and annoyance of floor impact noise. The heavy-weight impact sounds were recorded through dummy heads and classified according to the frequency characteristics of the floor impact sounds. The characteristics of the floor impact noise were investigated by paired comparison tests and semantic differential tests. Sound sources for auditory experiment were selected based on the actual noise levels with perceptual level differences. Auditory experiments were also conducted to investigate the relationship between level indices and subjective responses. The results show that L<sub>Aeq</sub> and L<sub>Amax</sub> are highly correlated with subjective response to heavy-weight impact sounds.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p367.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p364" class="affilation"></a>Reducing the Heavyweight Impact Sound Levels in Reinforced Concrete Structures Using Viscoelastic Damping Materials</h2>
<h3>Jin Yong Jeon, Seung Yup Yoo, Pyoung Jik Lee, Young Jeong</h3>
<p class="affilation">School of Architectural Engineering, Hanyang University, Seoul 133-791, Korea</p>
<p><b>ABSTRACT</b><br>
Floating floors with resilient isolators inserted between the structural slab and the upper layer of the floor structure have been generally used because of their effectiveness in lightweight impact sound isolation. However, these isolators often amplify low-frequency sounds below 100 Hz. Therefore, a new damping viscoelastic material has been developed to reduce heavyweight impact sound levels in box frame-type reinforced concrete structures. The viscoelastic materials can be embodied between the concrete slab and the upper layer of the floor structure as a constrained layer and the energy from floor impacts is absorbed with shear and or compressional damping characteristics.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p364.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p476" class="affilation"></a>Investigation of a Two-Parameter System of Evaluating Impact Noise Insulation</h2>
<h3>John J. LoVerde, Wayland Dong</h3>
<p class="affilation">Veneklasen Associates, 1711 Sixteenth St, Santa Monica, CA 90404, USA</p>
<p><b>ABSTRACT</b><br>
Impact insulation is currently measured using a tapping machine and described with a single number metric, L’<sub>n,w</sub> defined in ISO 140 and 717, or Impact Insulation Class (IIC) defined in ASTM E492 and E1007. It is well known that these metrics do not correlate well with subjective reaction. Numerous proposals have been made to modify the procedure or floor excitation method in order to develop a metric that better correlates with reaction. However, to our knowledge all such proposals have continued to define the use of a single-number metric to describe acoustical performance. Past research by the authors has shown that in lightweight construction, subjective reaction is much better correlated with low-frequency thudding from footfalls in the 63 Hz octave band than with IIC. Recent experience in concrete buildings (where thudding is not traditionally a concern) indicates that mid and high-frequency impact noise from heel clicks, dragging furniture, etc., are also not well correlated with IIC or L’<sub>n,w</sub>. Experience suggests that the low-frequency impact sound pressure level (ISPL) is influenced by different variables than the mid/high-frequency ISPL, and that the two may be largely independent. If so, it follows that no single-number metric will be able to adequately characterize an assembly. A two-domain system, where the first domain describes the low-frequency performance and the second domain describes the mid/high-frequency performance, is investigated to determine if it results in improved methods for evaluation and rank-ordering of floor/ceiling assemblies.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p476.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p7" class="affilation"></a>The Directivity of the Forced Radiation of Sound from Panels and Openings</h2>
<h3>John Laurence Davy (1,2), Thomas Kannanaikkel John (3)</h3>
<p class="affilation">(1) School of Applied Sciences, RMIT University, GPO Box 2476V Melbourne, Victoria 3163, Australia (2) CSIRO Manufacturing & Materials Technology, PO Box 56 Highett Victoria 3190, Australia (3) School of Aerospace, Mechanical and Manufacturing Engineering, RMIT University, GPO Box 2476V Melbourne, Victoria 3163, Australia</p>
<p><b>ABSTRACT</b><br>
This paper presents a method for calculating the directivity of the radiation of sound from a two dimensional panel or opening, whose vibration is forced by the incidence of sound from the other side. The directivity of the radiation depends on the angular distribution of the incident sound energy. For panels or openings in the wall of a room, the angular distribution of the incident sound energy is predicted using a physical model which depends on the sound absorption coefficient of the room surfaces. For an opening at the end of a duct, the sound absorption coefficient model is used in conjunction with a two dimensional model for the directivity of the sound source in the duct. The finite size of the duct or panel is taken into account by using a two dimensional model for the real part of the radiation efficiency of the finite size panel or opening. For angles of radiation close to 90° to the normal to the panel or opening, the effect of the diffraction by the panel or opening, or by the finite baffle in which the panel or opening is mounted, needs to be included. The directivity of the radiation depends strongly on the length of the radiating object in the direction of the observer and only slightly on the width of the object at right angles to the direction of the observer. For panels, the plate wave impedance of the panel is used. Above its critical frequency, a single panel radiates strongly at the angle at which coincidence occurs. The method is compared with published experimental results.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p7.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p577" class="affilation"></a>Comparison of Experiment, Finite Element and Wave Based Models for Mass Inclusions in Poro-Elastic Layers</h2>
<h3>M. R. F. Kidner (1), Kamal Idrisi (2), J. P. Carneal (2), M. E. Johnson (2)</h3>
<p class="affilation">(1) Acoustics, Vibration & Control Group, Dept of Mechanical Engineering The University of Adelaide, SA 5005, Australia (2) Vibration and Acoustics Laboratory Dept. of Mechanical Engineering, Virginia Polytechnic, Institute and State University Blacksburg VA 24061, USA</p>
<p><b>ABSTRACT</b><br>
The addition of small mass inclusions into the poro-elastic layer was found to create an increase in insertion loss (IL) over a broadband frequency range, usually below 1000 Hz. In this paper, results of two models: a simplified closed form approximation to the frame dynamics and a fully couple finite element analysis, are compared to experimental results. The motivation is the large computational effort that is required by the fully coupled 3-D finite element model of the poroelastic material makes optimization prohibitive in terms of time/computational power. Proof of equivalency of the analytical approximation, the FEA model and experimental data allows the former to be used in the optimization of inclusion design. Results from the fully coupled 3-D model, an approximation to the Biot model, and an experimental investigation are compared and discussed.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p577.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p690" class="affilation"></a>Correlation of Impact Isolation Test Results Using Standard Tapping Machine and Heavy/soft Impact Source</h2>
<h3>Nicholas Tselios, Tony Wong, Mathew Simon</h3>
<p class="affilation">Renzo Tonin & Associates (NSW) Pty Ltd, 1/418A Elizabeth Street, Surry Hills, NSW 2010, Australia</p>
<p><b>ABSTRACT</b><br>
Currently the use of a standard tapping machine is the primary method for measuring the impact sound of floors and the reduction of transmitted impact sound by floor coverings. The tapping machine is made of five small metal hammers striking the floor with successive impacts to create a noise which is measured from the floor below. The resultant weighted normalised and standardised impact sound pressure levels are determined for the performance of the floor. An alternative method in IS0 140-11 is the Drop Ball Test which is used to determine the A-weighted average fast maximum level, L<sub>AF max</sub> of a flooring system. It involves the dropping of a standardised ball weighing 2.7 kg from a height of 1m onto a floor and measuring the noise level below. It is generally acknowledged that the Drop Ball Test is quicker, simpler and less costly to conduct than the Standard Tapping Machine test. The investigation undertaken has identified a correlation between the L<sub>n,Tw</sub>, L<sub>n,Tw</sub> + C<sub>I</sub> values and the L<sub>AF max</sub>. The relationship is dependent on factors such as floor surface coverings, ceiling type, construction, insulation and floor thickness. Hence this phenomenon can be utilised to replace the Standard Tapping Machine Test with the Drop Ball Test in the determination of a floor’s impact sound insulation rating.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p690.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p779" class="affilation"></a>A Study on the Measurement of Sound Insulation of a Small-Size Window</h2>
<h3>Sang-Ryul Kim, Hyun-Ju Kang, Jae-Seung Kim, Hyun-Sil Kim, Bong-Ki Kim</h3>
<p class="affilation">Acoustics Team, Korea Institute of Machinery and Materials, 171 Jang-dong, Yuseong-gu, Daejeon, 305-343, Korea</p>
<p><b>ABSTRACT</b><br>
In order to measure the sound transmission loss(STL) of a test specimen such as a window and a door, which is smaller than the test opening, a special partition is built into the test opening and the specimen is placed in that partition. This paper discusses how the measured STL of a small-size window is changed by the partition. Theoretical investigations are carried out to quantify the effect of the filler wall. The results reveal that the insufficient sound insulation of the filler wall lowers the measured value of the window’s STL. How to obtain the more accurate STL of a small-size window even with the insufficient sound insulation of the filler wall is also introduced and discussed in comparison with the experimental results. The comparison shows the possibility of the proposed method in practical applications.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p779.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p575" class="affilation"></a>Implementation of a Hybrid Model for Prediction of Sound Insulation of Finite-Size Multilayered Building Elements</h2>
<h3>Selma Kurra</h3>
<p class="affilation">Department of Architecture, Acoustics Unit, Bahcesehir University, Cıragan Cad. Osmanpasa Mektebi Sokak No: 4 - 6, Besiktas, Istanbul 34100 Turkey</p>
<p><b>ABSTRACT</b><br>
In building acoustics, it is necessary to have a reliable prediction model to obtain the sound transmission loss of layered structures especially for the building facades exposed to noise. Traditional models are not very much applicable in most of the cases, since the building elements are multilayered structures comprised of different layer combinations with various physical characteristics, such as solid homogenous layers, porous or foamed material, elastic damping layers, etc. The previous model that has been developed by integrating the impedance approach for infinite-size layered systems and the windowing technique for finite-size elements, was computerized as a time efficient program. The predicted results were confirmed by the laboratory experiments as satisfactory for use in insulation practice for acquiring the 1/3 octave band sound transmission losses as well as the rating values; Rw(C; Ctr). This paper describes the model briefly and refers to some implementations in search for the effects of particular layer parameters.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p575.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p469" class="affilation"></a>Guide for Flanking Sound Transmission in Wood Framed Construction - Airborne Sources</h2>
<h3>T. R. T. Nightingale, J.D. Quirt, F. King</h3>
<p class="affilation">Institute for Research in Construction National Research Council Canada, Ottawa, K1A 0R6, Canada</p>
<p><b>ABSTRACT</b><br>
This paper reports results from continuing studies of sound transmission between adjacent units in wood-framed multi-dwelling buildings conducted at in the Flanking Transmission Facilities at IRC/NRC. The paper examines how common construction details affect structure-borne (flanking) transmission between adjacent rooms. Previous reports from our multi-year experimental study showed that the dominant flanking path between horizontally, vertically and diagonally separated rooms typically involved the exposed surface of the floor. This paper reports on the most recent study, which revealed that there are a number of other transmission paths involving the sidewalls, and ceilings, which become collectively important once the more obvious paths are addressed. Estimates of the apparent sound insulation were obtained by summing the energy transmitted directly through the separating wall or floor assembly with that for all the flanking paths involving the wall/floor/ceiling surfaces abutting the separating construction. These estimates provide the basis for a design guide T to predict sound isolation in typical wood-framed row housing or apartment buildings.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p469.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p574" class="affilation"></a>The Road Traffic Noise Attenuation by External Wall of Office Building in Standard Work Conditions</h2>
<h3>Witold Mikulski</h3>
<p class="affilation">Central Institute for Labour Protection - National Research Institute, Warsaw, Poland</p>
<p><b>ABSTRACT</b><br>
In many cases a road traffic noise is indicated by workers as one of basic factors of noxious work at office workplaces, so it is necessary to estimate it. There are few methods to estimate the road traffic noise at workplaces in the office buildings. Those methods are based on the results of noise assessment in the surrounding and sound insulation of external wall when the windows are closed. In those cases parameter which describes noise attenuation of the wall is sound insulation. The value of this parameter is quite this same as the value of the windows. But in standard work conditions the windows are often open, half-open, or untight. Therefore in order to predict SPL at the workplace in standard work conditions, it is necessary to take into account how the sound insulation of the external wall depends on the opening of the window.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p574.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p824" class="affilation"></a>FFT Based Complex Critical Band Filter Bank and Time-Varying Loudness, Fluctuation Strength and Roughness</h2>
<h3>Lingsong He (1), Malcolm J. Crocker (2), Ran Zhou (2)</h3>
<p class="affilation">(1) School of Mechanical Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China (2) Department of Mechanical Engineering, Auburn University, 201 Ross Hall, Auburn University, AL 36849-5341, USA</p>
<p><b>ABSTRACT</b><br>
This paper describes a new algorithm for producing a complex critical band filter bank and its application in computing time-varying loudness, fluctuation strength and roughness. A digital Butterworth filter bank is used to define the frequency characteristics of the critical band filter bank and then transform it into a complex critical band filter bank by use of the Hilbert transform. An FFT transform is used to transform the noise signal into the frequency domain, and then the noise signal is separated into critical bands by multiplying it by each critical band filter. Finally multi-IFFT transforms are employed to transform each filtered signal into the time domain in two orthogonal parts or into a complex signal form. Thus the envelope curve can be obtained for each bark band from the amplitude of the complex signal. The instantaneous energy of the envelope curve for each critical band is the instantaneous loudness in that critical band and the depth of the envelope curve of each critical band is proportional to the fluctuation strength and roughness in that critical band.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p824.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p61" class="affilation"></a>Three-Dimensional Acoustic Displays in a Museum Employing WFS (Wave Field Synthesis) and HOA (High Order Ambisonics)</h2>
<h3>Angelo Farina (1,2), Andrea Capra (1,2), Paolo Martignon (1,4), Simone Fontana (1,2,3), Fons Adriaensen (1), Paolo Galaverna (1), Dave Malham (5)</h3>
<p class="affilation">(1) LAE - Laboratory for Acoustics and Electroacoustics, Parma, Italy (2) University of Parma, Industrial Engineering Dept., Parma, Italy (3) Ecole Nationale Superieure de Telecommunications (ENST), Paris, France (4) University of Ferrara, Engineering Dept., LAV (Laboratory for Acoustics and Vibrations) Ferrara, Italy (5) Music Research Centre, Department of Music, The University of York, UK</p>
<p><b>ABSTRACT</b><br>
The paper describes the sound systems and the listening rooms installed in the new “museum of reproduced sound”, actually being built in Parma, restoring an ancient church. The museum is devoted to the exposition of a huge collection of antique radios and gramophones, but it will also exploit the frontiers of modern methods for immersive surround reproduction: WFS and HOA. In the main hall, a large planar WFS loudspeaker array is employed for inviting the visitors to enter the world of sound reproduction, providing stunning effects and emotional sounds enveloping them from many directions. At the end of the exposition path, a special HOA space is employed for showing the recent developments of recording/reproduction methods started from the Ambisonics concept, capable of creating natural reproduction of sport events, live music and other immersive acoustical experiences; in this room also a binaural/transaural system is available. A second, larger listening room capable of 30 seats is equipped with a horizontal WFS array covering the complete perimeter of the room. The paper describes the technology employed, the problems encountered due to the difficult acoustical conditions (the museum was formerly a church), and the novel software tools developed for the purpose on LINUX platforms.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p61.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p158" class="affilation"></a>Psychoacoustic Evaluation of a New Earpiece for Augmented-Reality Audio</h2>
<h3>Craig T. Jin, Aengus Martin, André van Schaik</h3>
<p class="affilation">School of Electrical and Information Engineering, University of Sydney, Sydney, NSW 2006, Australia</p>
<p><b>ABSTRACT</b><br>
An augmented-reality audio system ideally provides a means to present virtual auditory space stimuli to a listener, without distorting the listener’s normal spatial hearing. In this work, we conduct a psychoacoustic experiment to evaluate both the virtual and real sound localisation fidelity of an augmented-reality audio system based on acoustically-transparent ear shells. In addition to being acoustically-transparent, the ear shells are comfortable to wear and relatively discrete and thus provide an attractive platform for presenting augmented-reality spatial audio. The results of the sound localisation tests indicate that high-fidelity spatial audio, i.e., spherical correlation coefficient generally greater than 0.87, but with individual variations, can be obtained.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p158.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p328" class="affilation"></a>Acoustic Clarity and Auditory Room Size Perception</h2>
<h3>Densil Cabrera</h3>
<p class="affilation">Faculty of Architecture, Design and Planning, University of Sydney, Sydney, NSW 2006, Australia</p>
<p><b>ABSTRACT</b><br>
Studies of auditory room size perception have sometimes found clarity index to be a good first order predictor of subjective ratings, with a negative correlation coefficient. However, for rooms of fixed reverberation time, the slope of the function relating clarity index to room volume is positive (for a given source-receiver distance). This paper considers how clarity index relates to room volume for realistic rooms, and why it can be an effective predictor of perceived room size.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p328.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p65" class="affilation"></a>Ambisonic Localisation - Part 2</h2>
<h3>Richard Lee (1), Aaron Heller (2)</h3>
<p class="affilation">(1) Pandit Littoral, Cooktown, Queensland 4895, Australia (2) 2SRI International, Menlo Park, CA 94025, USA</p>
<p><b>ABSTRACT</b><br>
An earlier paper examined the performance of “Classic” horizontal Ambisonic surround sound systems with speakers arranged in regular polygons or as diametrically opposite pairs. We extend the work to non-traditional Ambisonic systems; ITU-R BS775 5.0 layouts supposedly used for domestic surround sound and also non-optimal decode, where the speaker array does not correspond to the decoder. Our interest is in simple enhancements possible with present day technology that could benefit the listener at home.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p65.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p512" class="affilation"></a>Binaural and Monaural Helmet Systems: Noise Considerations</h2>
<h3>Tomasz Letowski, Larry Ferguson</h3>
<p class="affilation">Human Research and Engineering Directorate, U.S. Army Research Laboratory, Aberdeen Proving Ground, MD 21005-5425, USA</p>
<p><b>ABSTRACT</b><br>
The main function of the combat helmet is to provide ballistic protection against small arms fire and fragmentation. However, the helmet also serves as a mounting platform for several systems enhancing the soldier’s situational awareness. The two main such systems are the helmet mounted (visual) display (HMD) and the radio (audio) communication interface. Audio interfaces may be built into the helmet or mounted directly on the head under the helmet shell. In both cases the main challenge in designing an effective audio interface is to provide radio communications and protect the soldier’s ears from high noise levels while permitting adequate auditory awareness. One solution is to mount small loudspeakers in the helmet shell and to provide stand-alone level-dependent hearing protection. This study addresses the issues of monaural and binaural speech reception using helmet-mounted transducers. Monaural and binaural audio interfaces built into the same type of helmet (PASGT) were compared with regard to speech recognition in noise using the Modified Rhyme Test. Several noise conditions differing in noise source location and noise level were investigated. Ten subjects participated in the study. The collected data reveal a 2-6 dB improvement in effective signal-to-noise ratio by changing from the monaural to the binaural version of the helmet and provide support for the energy model of speech intelligibility summation across left and right ear channels. A signal-to-noise ratio of about 0 dB or better is needed to provide the 91% binaural speech intelligibility required by MIL STD 1472D.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p512.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p55" class="affilation"></a>Driver Exposure to Noise from Audio Tactile Line Marking in Queensland</h2>
<h3>Daniel Naish</h3>
<p class="affilation">Queensland Government, Department of Main Roads, 477 Boundary Street, Spring Hill, Brisbane, Queensland, Australia</p>
<p><b>ABSTRACT</b><br>
This study, which was funded by the Queensland Department of Main Roads, conducted various acoustic measurements near a vehicle driver’s left and right ear position for a number of different test conditions to determine the change in noise level introduced by Audio Tactile Line Marking (ATLM). ATLM’s are the ribbed profiles placed over the edge lines or centrelines of roads with the purpose of raising the awareness and alertness of a vehicle driver that the vehicle is travelling outside the bounds of its carriageway. The ATLM induces an audible and vibratory signal inside the cabin of the vehicle, however only the audible signal is investigated in this study. A site with a recently installed ATLM (250 mm spacing with 5 to 6 mm rib heights) was chosen for this study. Tests were conducted in standard passenger vehicles at 100 km/hr, 90 km/hr and 80 km/hr. The results showed that for parameters LA10, LA5, LA1 and LAmax, the ATLM is observed to raise overall levels by 7 dB(A) to 9 dB(A) with little differences due to vehicle speed. Most of the additional acoustic energy is located at the fundamental frequency of the ATLM and up to the 3rd harmonic with the general spread of additional energy being between 50 Hz and 500 Hz. Also it was found that the left ear is subject to slightly higher noise increases than the right ear.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p55.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p816" class="affilation"></a>But are the trains getting any quieter?</h2>
<h3>David Thompson</h3>
<p class="affilation">Institute of Sound and Vibration Research (ISVR)
University of Southampton
Southampton SO17 1BJ
UK</p>
<p><b>ABSTRACT</b><br>
To reduce railway noise effectively a good knowledge of the source mechanisms is first required. Wheel/rail interaction, in particular, results in a multiple source environment where wheels, rails and sleepers all play a role. This is a classic noise control problem where treatments will not be successful unless they take account of the relative importance of each source and appropriate measures are applied for all the significant sources. Starting from theoretical research into source modelling, a number of practical techniques will be discussed that have been developed for reducing railway noise in the last 10-20 years. The difficulties of practical implementation will also be discussed, recognising that the railway industry faces many pressures that make it reluctant to change.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p816.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p383" class="affilation"></a>Study on Calculating Acoustic Sensitivity of Car Cab Based on Finite Element Method</h2>
<h3>Fangli Ning (1), Geng Liu (1), Juan Wei (2)</h3>
<p class="affilation">(1) College of Mechanical and Electrical Engineering, Northwestern Polytechnical University, Xi’an, P. R. China (2) State Key Lab.of Integrated Service Networks, Xidian University, Xi’an, P. R. China</p>
<p><b>ABSTRACT</b><br>
The comfort in the car cab is a key element for modern car, which could determine the customers’ viewpoint to the car. The noise of frequency range from 30Hz to 200Hz in the car cab is called booming noise. This kind of noise could make passengers feel oppression, fret and tired. In order to decrease booming noise pressure, acoustic design variables of car cab, such as car cab geometry, the thickness of panel, the surface admittance of panel etc, should be designed optimization. Acoustic sensitivity of car cab is defined as the sensitivity of the interior sound pressure with respect to an acoustic design variable, which is very useful characteristic for design optimization of car cab. In this paper, firstly, finite element method (FEM) model is given for calculating booming noise pressure of car cab. Secondly, based on above FEM model, numerical method for acoustic sensitivity is presented. Thirdly, acoustic sensitivity is decomposed to acoustic magnitude sensitivity and acoustic phase sensitivity. Lastly, acoustic sensitivity of one NASTRAN model of car cab is calculated.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p383.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p162" class="affilation"></a>Noise in Highways: Development of a Statistical Prediction Model</h2>
<h3>Frederico Rodrigues (1), Marco Antônio de Mendonça Vecci (2), Frederico Luiz C. Moura (2)</h3>
<p class="affilation">(1) Tectran - Técnicos em transporte LTDA, R. Pirapetinga 322, 8° andar, Belo Horizonte-MG, Brazil (2) Universidade Federal de Minas Gerais, Departamento de Estruturas, R. Espirito Santo, 35 Centro, CEP 31160-030, Belo Horizonte-MG, Brazil</p>
<p><b>ABSTRACT</b><br>
Predicting sound levels proceeding from urban streets or highways is a constant necessity in traffic noise investigation. The development of models to explain the noise as a function of, specially, vehicle flow, is a common procedure to handle this issue. In this way, a major research on a highway close to Belo Horizonte - Brazil is being carried out and a noise data base is being generated to include vehicle flow and distance between the source and the receptor. The goal of this work is to validate a statistical model to predict sound levels from the highway which is receiving new lanes. In the near future this highway expansion will attract more traffic which will, by its turn, increase its own noise levels. The predicted noise modelling under consideration has shown good agreement with the measured data already available.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p162.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p35" class="affilation"></a>Vibrations of Multi-Span Bridges Under Moving Loads</h2>
<h3>Hongan Xu, Wen L. Li</h3>
<p class="affilation">Department of Mechanical Engineering, Mississippi State University, Mississippi State, MS 39762, USA</p>
<p><b>ABSTRACT</b><br>
This study is concerned with the dynamic behavior of generic multi-span bridges under a concentrated moving load. In this multi-span bridge model, each span can be independently supported by up to eight elastic springs, thus allowing a more general and realistic representation of many joints and intermediate supports of practical concern. Additionally, since the displacement and its first derivative are no longer required to be continuous at an intermediate support, this model is capable of accounting for the vehicle-bridge interactions resulting from the possible steps and skew angles at the span junctions. Numerical results are presented with a focus on the dynamic impact of the coupling conditions between spans. It has been shown that the deflection on each span strongly depend upon its local coupling conditions, especially near the critical stiffness values defined by the bending rigidities of the involved beams. A fairly large variance of response has also been observed on each span in correspondence to a wide range of stiffness values, which implies a good potential for improving bridge performance through varying joint stiffnesses and/or coupling configurations. This analysis method can be readily applied to any boundary and coupling conditions with no need of changing or modifying the formulations or solution procedures.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p35.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p409" class="affilation"></a>Reduction of Ground Vibration by Means of Ground Improvement Along a Railway Track</h2>
<h3>Jin-Ho Kim (1), Hyo-Jung Cha (2)</h3>
<p class="affilation">(1) Department of Track & Civil Engineering, Korea Railroad Research Institute, #360-1 Woulam-dong, Uiwang-si, Korea (2) Engineering Development Team, Korea Rail Network Authority, #452-3 Daeheung-dong Jung-Gu, Daejeon-si, Korea</p>
<p><b>ABSTRACT</b><br>
The ground vibrations induced by high-speed train have drawn engineering attention in recent years, since high-speed trains are growing rapidly throughout Europe, East Asia, and North America. Deep mixing technology, that has a wide range of application in the construction industry, has been used to mitigate the detrimental effects of vibration caused by high-speed trains. Deep mixing is a ground modification technology that mixes in situ soil with a cementitious material to produce overlapped columns using specially designed equipment with paddles and/or augers. This paper aims to examine and synthesize the latest advancements when deep mixing technology is used as the countermeasure against vibration control. Excitation mechanism caused by a moving load that provides the basis for train induced vibration is discussed. The current state of practice to analyse and predict the response of treated ground based on the analytical and numerical solutions are presented along with a summary of field data. The rigorous numerical solutions with 3-D modelling capabilities have demonstrated effective tools to predict improvement effect of deep mixing as a countermeasure for vibration control.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p409.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p119" class="affilation"></a>A Model for Calculating Vibration from a Railway Tunnel Buried in a Full-Space Including Rigid Bedrock</h2>
<h3>L. Rikse (1), H. E. M. Hunt (2), M. F. M. Hussein (3), G. Degrande (1), S. Gupta (1)</h3>
<p class="affilation">(1) K.U.Leuven, Department of Civil Engineering, Kasteelpark Arenberg 40, B-3001 Leuven, Belgium (2) Engineering Department, University of Cambridge, Trumpington Street, Cambridge, CB2 1PZ, UK (3) School of Civil Engineering, University of Nottingham, Coates Building University Park, Nottingham, NG7 2RD, UK</p>
<p><b>ABSTRACT</b><br>
Subway induced vibration has become an important environmental problem. Ground borne noise and vibration have a significant impact on the comfort of inhabitants of buildings near railway tunnels. Therefore, legislation has become strict and the design of vibration countermeasures is of increasing importance. Engineers need accurate and fast running models. Over the last 10 years a computationally efficient model, known as the Pipe-in-Pipe (PiP) model, has been developed. In its basic formulation, the PiP model accounts for a tunnel in a full space. Two methods are presented in this paper to account for a rigid bedrock underneath the tunnel. The first is the mirror-image method and takes the bedrock into account by mirroring the tunnel and the applied load around the soil-bedrock interface. Vibration generated by the mirrored load represents the reflected wave field. The mirror image method is very efficient but it is only an approximation of the real boundary condition at the soil-bedrock interface. The second method is a new development of the PiP model and is based on the assumption that the near field displacements are not influenced by the existence of the rigid bedrock. Green’s functions for a full space are used to calculate the internal source in a full space that would produce the same displacements at the tunnel-soil interface as calculated by the original PiP model (e.g. a tunnel in a full-space). This internal source is then used to calculate the far field displacement by using Green’s functions for a half-space with a fixed surface. The two different methods are compared with an alternative Finite Element-Boundary Element (FE-BE) model, from which it is concluded that the modified PiP model produces more accurate results then the mirror-image method.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p119.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p602" class="affilation"></a>Study on Using Noise for Adhesion Control System of Railway Vehicle</h2>
<h3>Maksym Spiryagin, Kwan Soo Lee, Hong Hee Yoo</h3>
<p class="affilation">School of Mechanical Engineering, Hanyang University, Seoul, 133-791, Korea</p>
<p><b>ABSTRACT</b><br>
Many existing control systems for vehicles use an effect of a prediction of a friction coefficient between wheels and rails. It is connected with the impossibility of measuring a friction coefficient at the moment of running vehicle movement. One of the ways to solve this task is to use noise spectrum analysis for friction coefficient detection. At the present time different noise sources are localized, calculated and measured for railway vehicles. Research shows that at a speed up to 300 km/h, the noise of wheel rolling on the surface is predominant. And the noise can be subdivided into three categories: rolling noise, grind and scream on the curve parts of roads and dynamical noise (usually, this noise depends on impact loads). However, the noise for wheel-rail interaction is less researched. The researches also have not done a diagnostic or a monitoring of technical conditions for the wheel-road contact (for example, third body in the contact zone between rail and wheel). Some of these conditions are able to have a negative effect on adhesion characteristics. The form of working contact surfaces has a major influence on the tense distribution, which also has a strong influence on the spectrum of noise. Based on this approach it is possible to develop an adhesion control system of railway vehicles. Results from this study will be presented and the effectiveness of this work will be discussed.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p602.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p582" class="affilation"></a>Structure-Borne Sound Contribution into Earth-Moving Machine Cabs</h2>
<h3>Nickolay Ivanov (1), David Copley (2), Natalia Tyurina (1)</h3>
<p class="affilation">(1) Baltic State Technical University, St. Petersburg, 190005, Russia (2) Caterpillar Inc., Peoria, IL 61629, USA</p>
<p><b>ABSTRACT</b><br>
The interior sound field of an earth-moving machine cab is formed by air-borne and structure-borne sound contributions. Structure-borne sound is generated by cab panels, which are in turn influenced by vibrations transmitted through cab mounts. These vibrations may originate from the internal combustion engine (i.c.e.) and other sources. Significant sound reduction in cabs may be obtained in machines where effective mounts (vibration isolators) are installed. Similarly, for some machines, higher levels of vibration are noticed at some frequencies, suggesting areas for improvement. Stricter noise emission requirements for earth-moving machines in many countries have initiated further investigations into noise and vibration reduction methods. A special experimental study was carried out in order to separate the airborne contribution from the total sound field in an earthmoving machine cab, thereby estimating the structure-borne noise contribution. A transfer function for structure-borne noise for the studied cab is presented.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p582.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p345" class="affilation"></a>Investigation of STL Measurement Method at the Vehicle Component Level and Correlation between Measurement and Prediction</h2>
<h3>Ri Guang Nan (1), Yong Jai Park (1), Yeon June Kang (1), Chul Min Park (2), Ki Sang Chae (2)</h3>
<p class="affilation">(1) Advanced Automotive Research Center, School of Mechanical and Aerospace Engineering, Seoul National University, Seoul 151-744, Korea (2) Research & Development Division, Hyundai & Kia motor Co., Korea</p>
<p><b>ABSTRACT</b><br>
The measurement method and the prediction of Sound Transmission Loss (STL) at the vehicle component level are presented. The sound intensity method was used to measure the STL, and Statistical Energy Analysis models were used to predict the acoustic performance of the system. Since the dash panel and the floor system mainly affect the NVH performance in the car compartment, the analysis process requires detailed SEA modeling and accurate measurement in these parts, which are made of many different kinds of acoustical materials. The measured data was in good agreement with the predicted data obtained by using the SEA model, and the results were helpful in determining the reliability.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p345.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p81" class="affilation"></a>On Reducing the Shock Response of a Single Degree of Freedom Vehicle Model by Switching the Damping Coefficient</h2>
<h3>Tim Waters (1), Youngjin Hyun (2), Michael Brennan (1)</h3>
<p class="affilation">(1) Institute of Sound and Vibration Research, University of Southampton, Southampton SO17 1BJ, UK (2) Vehicle dynamic lab, R&D centre, Hyundai motors</p>
<p><b>ABSTRACT</b><br>
This paper concerns the acceleration response of a vehicle traversing a road bump. A linear viscously damped single degree of freedom model is adopted initially from which closed form expressions for the time response are obtained. By assuming the impulse to be of short duration relative to the natural period, these expressions simplify to show that the peak acceleration response is approximately proportional to the damping ratio. Numerical simulations are then presented for two alternative damping models: a piece-wise linear model, in which the damping ratio is different in the jounce and rebound directions; and a switchable damper that switches to a lower value during the impulse. The piecewise linear damper delivers modest reductions in peak acceleration when, as is common practice in automotive dampers, the damping is less in jounce than rebound. Larger reductions are achievable from the switchable damper and a simple approximate expression is given for the maximum possible reduction.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p81.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p271" class="affilation"></a>Experimental Verification of Full Vehicle Sea Model</h2>
<h3>Yong Jai Park (1), Ri Guang Nan (1), Yeon June Kang (1), Chul Min Park (2), Ki Sang Chae (2)</h3>
<p class="affilation">(1) Advanced Automotive Research Center, School of Mechanical and Aerospace Engineering, Seoul National University, Seoul 151-744, Korea (2) Research & Development Division, Hyundai & Kia motor Co., Korea</p>
<p><b>ABSTRACT</b><br>
Statistical Energy Analysis has been applied widely to improve the accuracy of the prediction of vehicle interior noise. Especially, in airborne noise cases, SEA is very useful for predicting the Interior noise of a vehicle if some parts of the vehicle model are changed. In this paper, a building and validating process of the full vehicle SEA model is presented. First, Sound Transmission Loss and Absorption Coefficient (α) of vehicle components are measured using a real vehicle. An airborne SEA model is built using the geometry information, and the component characteristics are modeled using STLs and α’s, which are measured or calculated. For the validation of the SEA model, the interior and exterior noises of a full vehicle were measured for various experimental conditions such as WOT (wide open throttle) condition and loudspeaker loading conditions. Finally, the predicted and the measured interior noises are compared, and the accuracies of the SEA model are identified for several loading conditions.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p271.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p178" class="affilation"></a>Comparison of Transmission Loss Models at Mid-Frequency against Shallow Water Data</h2>
<h3>Adrian D. Jones (1), Janice Sendt (2), Alec J. Duncan (3), Paul A. Clarke (1), Z. Y. Zhang (1), Amos L. Maggi (3)</h3>
<p class="affilation">(1) Defence Science and Technology Organisation, P.O. Box 1500, Edinburgh, SA 5111, Australia (2) Thales Australia, 274 Victoria Road, Rydalmere, NSW 2116, Australia (3) Centre for Marine Science & Technology, Curtin University of Technology, GPO Box U1987, Perth WA 6845, Australia</p>
<p><b>ABSTRACT</b><br>
To address the vexed issue of validation of transmission loss models for application to the mid-range of acoustic frequencies, a round-robin approach has been adopted in which the outputs from a number of models have been compared. Emphasis has been placed upon the requirements for models for circumstances relevant to continental shelf ocean zones within the Australian region. In particular, the ability to describe transmission in both ducted and downward refracting environments has been considered. To ensure realism in the modelling, all scenarios selected for comparison correspond with ocean tracks for which environmental parameters had been collected, and received sound pressure time series measured. The acoustic signal sources used for these at-sea data collections were small explosives. The subject transmission loss models are from of a variety of types, and these use different techniques to describe the characteristics of the ocean environment. To enable the most valid comparison of results, input parameters have been matched across models to the fullest extent. To attain the closest adherence to the at-sea situation, the seafloor acoustic properties selected for model inputs were those obtained for each track by an in-situ technique developed by DSTO. This paper presents the state of progress of this work, including a comparison of models amongst themselves and against measured transmission loss.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p178.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p389" class="affilation"></a>Response of Hull Plates Due to Turbulent Boundary Layers</h2>
<h3>Anders Nilsson, Fredrik Birgersson</h3>
<p class="affilation">MWL (The Marcus Wallenberg Laboratory for Sound and Vibration Research), KTH, 10044 Stockholm, Sweden</p>
<p><b>ABSTRACT</b><br>
Abstract A model has been developed for the prediction of velocity levels of ships hull plates which are excited by turbulent boundary layers. The model is based on the theory developed by Corcos. It is found that the velocity of the hull plates strongly depends on the speed of the ship. The acoustic power induced in the hull can be reduced if the thickness of the hull plates is increased. Other parameters like frame distance and height of hull plate are of secondary importance. The effect of turbulent boundary layer excitation is most efficiently reduced by changing the hull shape or by changing the transmission path from the hull plates to the accommodation decks.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p389.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p305" class="affilation"></a>The Study on the Effect of the Lateral Vibration of Shafting on Underwater Structural Acoustic Radiation</h2>
<h3>Cao Yipeng, Zhang Wenping</h3>
<p class="affilation">College of Power and Energy Engineering, Harbin Engineering University, Harbin, Heilongjiang, PR China</p>
<p><b>ABSTRACT</b><br>
For the propeller running in the non-uniform wake fluid field, the lateral vibration of shafting is caused by the lateral propeller-excited force. The lateral vibration of shafting is transmitted through bearing supporting to underwater structure, which causes strong radiated noise from underwater structure. In this paper, the finite element method is adopted to build the finite element model of underwater structure with shafting, and calculate the vibration response of nodes on the interface between the structure and the fluid. The direct boundary element method is used to calculate the underwater structural acoustic radiation. Base on the finite element model, the effects of different stiffness of front or rear shafting bearing and different stiffness of supporting structure on reducing underwater structural acoustic radiation caused by the lateral vibration of shafting are discussed.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p305.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p341" class="affilation"></a>Assessing the Impact of Underwater Noise on Marine Fauna: A Software Tool</h2>
<h3>Christine Erbe (1), Scott Carr (2)</h3>
<p class="affilation">(1) JASCO Research Ltd., 55 Fiddlewood Crescent, Bellbowrie, QLD 4070, Australia (2) JASCO Research Ltd., 432-1496 Lower Water St., Halifax NS, B3J 1R9, Canada</p>
<p><b>ABSTRACT</b><br>
A software package is presented which models the effects of underwater noise on marine mammals. It consists of three main parts: an acoustic source model, a sound propagation model and a bioacoustic impact model. It has been corroborated in the field by measurements of the noise field, and visual and passive acoustic surveys of marine mammals. The software package was written for Environmental Impact Assessments (EIA), and has been used to aid research, to apply for permits of marine operations, to monitor marine mammals, to design mitigation protocols, and to guide environmental management and decision-making. This article gives an overview of our software and presents results of various EIAs.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p341.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p489" class="affilation"></a>Advances in Monitoring and Mitigation of Ship Signatures</h2>
<h3>D. Hutt, M. L. Seto, L. Gilroy</h3>
<p class="affilation">Defence R&D Canada - Atlantic Canada, Dartmouth, Nova Scotia, B2Y 3Z7, Canada</p>
<p><b>ABSTRACT</b><br>
Signatures are the physical manifestations of a ship that can be exploited by military systems to detect, identify, track, or target it. Signature management is a strategy to minimize a ship’s susceptibility to attack by reducing its signatures. For the past ten years Defence R&D Canada - Atlantic has been developing an experimental Ship Signature Management System (SSMS) which performs real-time monitoring of the ship’s systems and environment in order to estimate its underwater acoustic and above water infrared signatures. The acoustic signature is derived primarily from the measurement of hull and machinery vibrations. The vibrations are further analyzed to track tonals which identify machinery or equipment that produce abnormal or unacceptable vibration levels. The infrared contrast signature is estimated from an array of temperature sensors and measurement of the background infrared radiance. The results of recent experiments with SSMS on Canadian research vessel CFAV Quest are reported here.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p489.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p269" class="affilation"></a>Application of Rational Orthogonal Wavelets to Active Sonar Detection of High Velocity Targets</h2>
<h3>David Bartel (1), Limin Yu (2), Lang White (2)</h3>
<p class="affilation">(1) Maritime Operations Division, Defence Science and Technology Organisation,SA 5111, Australia (2) School of Electrical and Electronic, The University of Adelaide, SA 5005, Australia</p>
<p><b>ABSTRACT</b><br>
This paper is concerned with the problem of detecting moving targets using active sonar. We study a promising class of waveform, the Rational Orthogonal Wavelets (ROWs), designed to be tolerant of multipath Doppler spreading. Recent work in communication has shown that ROWs are effective even on severely spread channels. We apply ROWs for the first time to target detection. ROW pulses are compared to conventional CW and LFM pulses via simulations involving a high-speed target in shallow water. The target is point-like, and ray tracing is used to synthesize Doppler-shifted multipath arrivals in a range-independent environment. The key feature of ROWs that we exploit is the orthogonality they maintain over a wide range of delays and Doppler scales. Thus the maximum-likelihood detector is a simple average of matched filters, and the statistics of the detector under the null hypothesis are known, permitting CFAR operation. In addition, a fast algorithm resulting in rational scaled filter banks is available.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p269.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p698" class="affilation"></a>Approaches for Automating Underwater Simulations by PE Method</h2>
<h3>Dmitry Yu. Mikhin</h3>
<p class="affilation">Acacia Research Pty. Ltd., Hendon SA 5014, Australia</p>
<p><b>ABSTRACT</b><br>
Modern Parabolic Equation (PE) models are capable of rapid and accurate predictions of underwater propagation. To achieve this goal they require not only highquality environmental data but also properly set model parameters, usually selected by a skillful practicing modeler. Automated simulation systems cannot rely on user skills and have to select their parameters through some heuristics. Commonly, the system designers choose a cautious approach and use conservative parameter settings, thus, sacrificing performance for accuracy. This paper examines possible approaches to simplify parameter selection. The paper is focused on using Nonlocal Boundary Conditions (NLBCs) to remove the user-defined parameters related to truncating the computational domain, the so-called “absorbing sponge’. In special cases, this approach allows additional speed-up of simulations through pre-computation of sound propagation in horizontally-independent medium layers.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p698.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p668" class="affilation"></a>Measurement of the Underwater Ship Noise by Means of the Sound Intensity Method</h2>
<h3>Eugeniusz Kozaczka (1,2), Ignacy Gloza (2)</h3>
<p class="affilation">(1) Gdansk University of Techology, G. Narutowicza 11/12, 80-952 Gdańsk, Poland (2) Polish Naval Academy, Smidowicza 69, 81-103 Gdynia, Poland</p>
<p><b>ABSTRACT</b><br>
The measurements carried out close to surface sources by means of determination the acoustical pressure only especially in reverberation surrounding are not representative to the real physical conditions connected with sound field distribution. In this paper the results of wide range investigations of the sound generation by the ship in the shallow water are presented. These results will be compared with the results carried out in the far field (using only sound pressure measurements results). Due to directional feature of sound intensity characteristics one can also observe the changes of movements of elementary source. There are shown the results of calibrations of the underwater intensity probes and also spectrograms of underwater noise generating by the ships.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p668.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p562" class="affilation"></a>Gauging of Hydroacoustic Transducers in Small-Scale Measurement Pools Using Continuous Signals</h2>
<h3>Igor Silvestrov</h3>
<p class="affilation">141570, State Research Institute of Physicotechnical and Radiotechnical Measurements VNIIFTRI, Mendeleevo, Moscow Region, Russian Federation</p>
<p><b>ABSTRACT</b><br>
The majority of the modern graduation methods used for determination of the hydroacoustic transducers sensitivity in small-scale measurement pools is based on the use of the “tone-burst” signals. This approach leads to the limitation of the low graduation frequency and to the decrease of the signal to noise ratio for the measurements. A method of gauging based on the use of continuous signals and the segregation of the spectrums for the measurement pool and the hydrophone being graduated is proposed in the article. The method under consideration allows decreasing the low graduation frequency in small-scale pools and increasing the signal to noise ratio.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p562.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p21" class="affilation"></a>Underwater Acoustic Propagation Model to Simulate Seismic Oceanography Experiments</h2>
<h3>Jean Kormann, Pedro Cobo, Carlos Ranz</h3>
<p class="affilation">Insituto de Acústica, CSIC Madrid, C/ Serrano144, 28006 Madrid, Spain</p>
<p><b>ABSTRACT</b><br>
Seismic reflection is a technique used for decades to profile the earth layering beneath the ocean with a high lateral and vertical resolution. In the other hand, oceanographers use probes to obtain the properties of the water layer with a rather lesser lateral resolution. Seismic oceanography focuses the powerful tools of seismics into the water layer to reveal its fine structure with a high lateral resolution. The re-processing of the in-water reflected waves in seismic data has allowed to image eddies, termohaline intrusions and internal waves. Synthetic models of such seismic experiments in water permit to foresee the effects of oceanographic gradients in the propagated waves. This paper describes a synthetic model of such seismic oceanography experiments. The model uses Berkhout convolution operators to extrapolate the wave field from the seismic source to the hydrophones taking into account the sound velocity structure of the water layer. Due to the small amplitudes of the scattered field, special attention is paid to the absorbing properties of the artificial boundaries of the medium.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p21.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p72" class="affilation"></a>Sonobuoy Display Integration</h2>
<h3>Jimmy Wang, Simon Lourey, Richard Ellem</h3>
<p class="affilation">Maritime Operations Division, Defence Science and Technology Organisation, PO Box 1500, EDINBURGH, SA 5111, Australia</p>
<p><b>ABSTRACT</b><br>
Sonar data integration can be performed at various levels throughout the sonar processing chain with varying complexity, cost and benefit. In this paper, we present research results on the integration of sonar data at the display level, which may potentially enhance the submarine detection capability for Anti-submarine Warfare (ASW) sonar systems. The primary aim of sonar display integration is to enhance the capability of a network of sonar systems in the detection of weak targets that may otherwise not be detected by an individual sonar system. We show that this can be achieved through the display integration of sonobuoy tactical displays with sea trial data. One added advantage of this technique is that once a weak target is detected it is also localised.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p72.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p717" class="affilation"></a>Improved Structure-Acoustic Interaction Models, Part I: Model Development</h2>
<h3>K. C. Park (1), Moonseok Lee (2), Youn-Sik Park (2), Youngjin Park (2)</h3>
<p class="affilation">(1) Department of Aerospace Engineering Sciences, University of Colorado, Boulder, CO 80309-0429, USA (2) NOVIC, Department of Mechanical Engineering, KAIST, 373-1 Guseong-dong, Yuseong-gu, Daejeon, 305-701, Korea</p>
<p><b>ABSTRACT</b><br>
An improved pressure-field governing equation has been developed for the modelling of external acoustic field interacting with flexible structures. The proposed interaction model is aimed to accurately capture both low and medium frequency interactions and to offers a frequency tailoring capability for a wider range of applications. The theoretical basis of the present model is the use of a combination of the retarded Kirchhoff potential and advanced potential to arrive at a stable second-order parametrerized approximate model. The present model is compared to the classical models of the first-order and second-order Doubly Asymptotic Approximations (DAA1 and DAA2) is shown to possess certain accuracy advantages. Numerical evaluations-of the proposed interaction model are carried out in a companion paper, Improved Structure--Acoustic Interaction Models, Part II: Model Evaluaion.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p717.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p297" class="affilation"></a>Ocean Acoustic Interferometry Experiment</h2>
<h3>Laura A. Brooks (1,2), Peter Gerstoft (1)</h3>
<p class="affilation">(1) Marine Physical Laboratory, Scripps Institution of Oceanography, La Jolla, CA, USA (2) School of Mechanical Engineering, the University of Adelaide, SA 5005, Australia</p>
<p><b>ABSTRACT</b><br>
Ocean acoustic interferometry (OAI) is a technique which relates the cross-correlations from a line of active sources to two receivers within a waveguide, and the time domain Green’s function between said receivers. Within this paper, three specific OAI source geometries are briefly introduced and explained. Experimental OAI data were collected during the SW06 (Shallow Water ’06) sea trials during September 2006. Preliminary analysis of the data shows that the cross-correlations exhibit an observable structure.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p297.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p622" class="affilation"></a>Acoustic Signature of a Submarine Hull</h2>
<h3>Mauro Caresta, Nicole Kessissoglou</h3>
<p class="affilation">School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney, NSW 2052, Australia</p>
<p><b>ABSTRACT</b><br>
A model to predict the acoustic signature of a submarine resulting from the radial vibration of the hull under axial excitation is presented. The simplified physical model of the submarine hull includes complicating effects such the presence of bulkheads, end enclosures, ring stiffeners and fluid loading due to the interaction with the surrounding medium. Under an axial symmetric force, only the ‘breathing’ modes of the cylinder corresponding to the n=0 circumferential modes are excited. To show the sound radiation due to the higher order nu22651 modes, a point axial force acting at one end of the shell has been considered. At low frequencies, the structural wavenumbers are generally subsonic. However, due to the finite cylinder, the wavenumber spectrum is a convolution of the spectrum of an infinite structure and a window generating radiation by means of the presence of supersonic components. The effect of the bulkheads on the structural and acoustic responses of the hull is also presented.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p622.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p718" class="affilation"></a>Improved Structure-Acoustic Interaction Models, Part II: Model Evaluation</h2>
<h3>Moonseok Lee (1), Youn-Sik Park (1), Youngjin Park (1), K. C. Park (2)</h3>
<p class="affilation">(1) NOVIC, Department of Mechanical Engineering, KAIST, 373-1 Guseong-dong, Yuseong-gu, Daejeon, 305-701, Korea (2) Department of Aerospace Engineering Sciences, University of Colorado, Boulder, CO 80309-0429, USA</p>
<p><b>ABSTRACT</b><br>
A parameterized external acoustic model interacting with flexible structures derived in the companion paper, Part I, is evaluated for its model fidelity employing a spherical shell. The mode-by-mode interaction equations of the present discrete model reveal that the model parameters introduced in the present acoustic interaction model can be tailored to match with either the dominant acoustic-structural interaction frequency or its damping ratio, but not simultaneously both. A least-squares fit of the mode-by-mode parameters leads to a parameterized matrix representation so that the present model can be implemented for general interaction surfaces. Comparisons of the present parameterized model with the classical Doubly Asymptotic Approximate (DAA) models show that the present model offers improved accuracy, especially for medium-frequency ranges.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p718.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p689" class="affilation"></a>Optimum Quasi-Adaptive Resonance Changer for Submerged Vessel Signature Reduction</h2>
<h3>Paul Dylejko (1), Nicole Kessissoglou (1), Yan Tso (2), Chris Norwood (2)</h3>
<p class="affilation">(1) School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney, NSW 2052, Australia (2) Defence Science and Technology Organisation (DSTO), Maritime Platforms Division, Fishermans, Bend, VIC 3207, Australia</p>
<p><b>ABSTRACT</b><br>
Reduction of radiated noise from maritime vessels is an important issue. A significant source of structure-borne sound corresponds to excitation of the vessel due to vibration transmission through the propeller-shafting system. This vibration transmission can be reduced using a resonance changer. A resonance changer introduces virtual elastic, damping and inertial influences by hydraulic means and thereby acts as a hydraulic dynamic vibration absorber. This paper theoretically examines the use of a quasi-adaptive and hybrid resonance changer system in the propeller-shafting system of a submarine to directly reduce the far-field radiated noise. Results show that a quasi-adaptive system exhibits similar performance to multiple passive resonance changers within the active frequency bandwidths. The significance of this result is that the quasi-adaptive resonance changer system uses only a single piston whereas multiple passive resonance changers each consist of their own piston. The hybrid system consists of an additional passive resonance changer to improve the broadband response.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p689.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p22" class="affilation"></a>Underwater Noise Impact of Offshore Wind Farms During Construction and Operation Phases</h2>
<h3>Pedro Cobo, Jean Kormann, Carlos Ranz</h3>
<p class="affilation">Instituto de Acústica. CSIC. Serrano 144, 28006 Madrid, Spain</p>
<p><b>ABSTRACT</b><br>
The two potentially noisier phases of an offshore wind farm are construction and operation. During the construction phase, high noise levels are radiated to the environment, both in air and water, due to engineering works such as pile driving. In the operation phase, the acoustic power radiated by each wind turbine is much lesser, but their usual life-span is 20-25 years. The aim of this paper is to describe a normal mode propagation model designed to predict the underwater noise impact afforded for an offshore wind farm in both phases. The model needs as inputs the acoustic data of the underwater sources (power level and spectrum), the oceanographic data of the medium (sound velocity and density in water and sediments, wind speed, depth, acoustic spreading law in the area) and the coordinates of the wind turbines. As a result, the model provides both the 2D overall noise map around the farm or the overall noise level along a line, as compared to the background noise.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p22.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p619" class="affilation"></a>A Boundary Element Package Containing Approximate Solvers for Treating High Frequency Acoustic Scattering</h2>
<h3>Ralf Burgschweiger (1), Martin Ochmann (1), Bodo Nolte (2), Ingo Schäfer (2)</h3>
<p class="affilation">(1) Technische Fachhochschule Berlin - University of Applied Sciences, Department of Mathematics - Physics - Chemistry, Luxemburger Str. 10, D-13353 Berlin, Germany (2) Forschungsanstalt der Bundeswehr für Wasserschall und Geophysik - Federal Armed Forces Underwater Acoustics and Marine Geophysics Research Institute, Klausdorfer Weg 2-24, D-24148 Kiel, Germany</p>
<p><b>ABSTRACT</b><br>
The target strength of objects submerged in water, located on the sea bottom or partially buried in the sediment can be calculated by means of a boundary element solver. For this reason, a boundary element code with suitable pre-/postprocessor and parallel working solvers is developed. The scattering objects within the transition range between fluid and sediment can be modeled by the preprocessor. It can manage large and complex meshes (more than 100,000 elements) and is able to import mesh-files in different standard formats (e.g. NASTRAN-, ANSYS- or CDB-format) or to generate meshes with closed surfaces. Combined with material parameters, this information is used as a database for the following high frequency scattering calculations. In the high frequency range, the computing time can be reduced drastically by using approximations instead of solving the complete system of BEM equations. For this reason, a so-called plane wave approximation (PWA) has been implemented in the BEM-package for evaluating the scattered sound pressure. As an alternative high-frequency approximation the Kirchhoff approach, in order to compare and validate the results of both high frequency approximations, is also used. The theory of these and additional high frequency approximations for scattering problems based on boundary integral equations is presented in another paper written by the authors. Results will be given for the scattering of plane waves from cylindrical shells located in the free space up to 100 kHz.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p619.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p730" class="affilation"></a>Spectral Characteristics of Wall Pressure Fluctuations for Surface Ships</h2>
<h3>Riccardo Broglia, Elena Ciappi, Andrea Di Mascio, Francesca Magionesi</h3>
<p class="affilation">INSEAN-Istituto Nazionale per Studi ed Esperienze di Architettura Navale, Via di vallerano 139, 00128 Rome, Italy</p>
<p><b>ABSTRACT</b><br>
Wall pressure fluctuations generated by the turbulent boundary layer (TBL) which extends on the wall of moving vehicles, play an important role in the mechanism of noise generation through fluid-structure coupling. In the case of marine applications, the calculation and the suppression of the radiated noise is crucial to ensure sonar efficiency as well as to improve the confort level on board new high speed vessels for passenger transportation. The studies performed in this field, most of them devoted to aeronautical applications and based on the analysis of experimental data, deal with equilibrium flow for which scaling laws for the power spectral density and theoretical models for the cross spectral density are available. The problem in the case of marine vehicles presents some peculiarities because of pressure gradients due to both free surface and hull curvature. Their effects on wall pressure spectra are in this work analyzed comparing pressure experimental data measured in different locations along the hull where favorable, adverse and zero pressure gradients are present. These particular zone are identified by analyzing the mean velocity and pressure field obtained by RANS numerical simulations. The results of this analysis provides interesting information on the characteristics of wall pressure spectra and on the validity of the scaling laws for the power spectral density in the presence of pressure gradients.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p730.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p615" class="affilation"></a>Excitation of a Submarine Hull by Propeller Forces</h2>
<h3>Sascha Merz (1), Nicole Kessissoglou (1), Roger Kinns (2)</h3>
<p class="affilation">(1) School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney, NSW 2052, Australia (2) Senior Visiting Research Fellow, University of New South Wales</p>
<p><b>ABSTRACT</b><br>
This paper begins with a review of the unclassified literature relating to the radiated sound-field of a submarine. Only sound generation induced by the propeller is considered. It is of interest to investigate excitation of the submarine hull due to fluctuating forces from the propeller that are transmitted to a submerged hull via both the external pressure field and the propeller shaft. This will assist in predicting the resulting underwater far-field pressure of the submarine due to direct sound radiation from the propeller and its hull vibration. The submarine hull is often modelled as a thin-walled cylinder with appropriate endcaps or, alternatively, as an ellipsoid. The hull deflection shapes excited by the vibratory shaft forces correspond primarily to the accordion modes. There is little unclassified work on the excitation of a submarine hull by the radiated sound field of the propeller. Some work has been done in order to determine the exciting forces acting on the hull without considering its vibrational response and fluid interaction. However, most of this work does not take into account the compressibility of the fluid. Subsequent research requires the development of meaningful models for the investigation of the combined effects and interactions of the exciting forces taking account of fluid compressibility and fluid-structure interaction. For this work, numerical methods such as finite element and boundary element methods (FEM, BEM), computational fluid dynamics (CFD) and their combination are of relevance. A fully coupled FEM/BEM model has been developed to investigate the the excitation of a submarine hull through the fluid and the shaft taking fluid compressibility into account. For a realistic hull, the induced vibration due to fluid forces was found to be between 10% and 50% of the vibration due to the shaft force.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p615.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p681" class="affilation"></a>Recent Developments in Fibre Optic Hydrophone Technology</h2>
<h3>Scott Foster, Steven Goodman, Alexei Tikhomirov, Mark Milnes and John van Velzen</h3>
<p class="affilation">Maritime Operations Division, Defence science and Technology Organisation, Edinburgh, SA 5111, Australia</p>
<p><b>ABSTRACT</b><br>
A brief overview of fibre optic acoustic sensor technology is presented, focussing on the application to ocean deployed sonar arrays. The potential advantages and limitations of different approaches are discussed. Current work by the authors on fibre laser based sensors is reported including the recent laboratory demonstration of a pressure compensated, all optical, low noise, fibre laser hydrophone.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p681.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p221" class="affilation"></a>Diver Detection Sonars and Target Strength: Review and Discussions</h2>
<h3>Z. Y. Zhang</h3>
<p class="affilation">Defence Science and Technology Organisation, P.O. Box 1500, Edinburgh, SA 5111, Australia</p>
<p><b>ABSTRACT</b><br>
Recent concerns about underwater intruder attacks on ships in port and harbour infrastructure raised strong interests in detecting divers. This paper reviews current research and systems on diver detection using acoustic means and the factors affecting system performance. Previous published data on diver acoustic target strength is discussed and seem to be plausibly explained by considering the acoustic scattering from a diver’s body and exhaled bubbles.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p221.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p159" class="affilation"></a>Some Study of Dynamic and Acoustic Character of Steerable Streamers for Ocean Exploration</h2>
<h3>Zhiping Zhao (1), Yaoqiang Zhu (2), Weikang Jiang (3)</h3>
<p class="affilation">(1) Yichang Testing Technique R&D Institute, 15 Tiyuchang Road, Yichang, Hubei Province, 443003, P. R. China, (2) R & D Center, China Oilfield Services Limited, P. O. Box 232, Beijing 101149, P. R. China (3) State Key Laboratory of Mechanical System and Vibration, Shanghai Jiaotong University, No.800, Dongchuan Road, Shanghai 200240, P. R. China</p>
<p><b>ABSTRACT</b><br>
The steerable streamers are used to control the orientation and depth of sonar hydrophone array in plotting a course for ocean exploration. The dynamic strength of the streamer steering device under impact is related with its reliability and life cycle. The acoustic noise radiated from its hull is a part of environment noise of the hydrophone in the cable banded streamer steering devices. Therefore, the dynamic character and flow noise of steerable device are key factors for ocean exploration, which are investigated in numeric simulation and experiment research respectively in this presentation. The hull of streamer steering device is made of polyurethane elastomer with a carbon-glass-fibre bush tube. The hyperelastic material model is used to simulate the polyurethane elastomer in finite element analysis of the steerable device hull. The material property parameters of the carbon-glass-fibre tube are identified by the experimental mode analysis. The impact of between the steerable device and shipboard in different velocity is simulated, and the results from numeric analysis suggest the impact limitation of steerable device. On the other hand, the acoustic noise due to flow induced by steerable device is measured in the tube with flow, in which the self noise under water of steerable device with different angle of steering wing as well as flow rates are investigated. The results show that the steerable devices would result in very low acoustic noise in ocean exploration at the cruising speed lower than 5 Kn.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p159.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p707" class="affilation"></a>Radiation Efficiency of Acoustic-Excited Plates with Stringer Attachments</h2>
<h3>Bilong Liu (1), Leping Feng (2)</h3>
<p class="affilation">(1) Institute of Acoustics, Chinese Academy of Sciences, Beijing, 100080, P. R. China (2) MWL, Department of Aeronautical and Vehicle Engineering, KTH , SE-100 44, Sweden</p>
<p><b>ABSTRACT</b><br>
The average radiation efficiency of acoustic-excited plate with stringer attachments is investigated by using a modal expansion method. This work is an extension to author’s previous publication (JSV 2007), where the predicted and measured sound transmission loss for curved aircraft panels was reported. For the plate and frequency range studied here, numerical results reveal that the radiation efficiency of acoustic-excited plate is very sensitive to the damping of the structure. Increasing the structure loss factor significantly increases radiation efficiency far below the plate critical frequency.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p707.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p753" class="affilation"></a>Attenuation of Shock Transmission Through a Launch Vehicle Payload Adaptor</h2>
<h3>Haisam Osman (1), Marty Johnson (2), Chris Fuller (2)</h3>
<p class="affilation">(1) United Launch Alliance, Huntington Beach, CA 92647, USA (2) Vibration and Acoustics Lab, Dept. of Mechanical Engineering, Virginia Tech, Blacksburg, VA 24061-0238, USA</p>
<p><b>ABSTRACT</b><br>
Shock transmission through aerospace structures is an important problem which has received a great deal of attention. Transient events generated throughout the flight envelope, such as lift-off and stage separation, can cause damage to delicate payload components. Attenuation of the transmitted shock is a very significant goal. This paper deals with the application of a light weight, optimally damped distributed vibration absorber for the control of shock transmission through a conical payload adaptor. This structure was modelled by finite elements and a matrix of mobilities was measured at a large number of points. The data was used to tune the frequencies of the absorbers, the damping, and their locations. A series of incremental impact tests where a minimum number of DVA’s were first installed and subsequently increased in stages were performed. The shock spectra at the top of the cone were computed from the transient time histories. The results indicated a wide band reduction in the transmitted shock. It confirmed that the light weight distributed vibration absorbers could be applied for significant shock attenuation.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p753.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p177" class="affilation"></a>Initial Assessment of the Ares I-X Launch Vehicle Upper Stage to Vibroacoustic Flight Environments</h2>
<h3>Jeffrey M. Larko, William O. Hughes</h3>
<p class="affilation">NASA Glenn Research Center, 21000 Brookpark Road, Cleveland OH 44135, USA</p>
<p><b>ABSTRACT</b><br>
The Ares I launch vehicle will be NASA’s first new launch vehicle since 1981. Currently in design, it will replace the Space Shuttle in taking astronauts to the International Space Station, and will eventually play a major role in humankind’s return to the Moon and eventually to Mars. Prior to any manned flight of this vehicle, unmanned test readiness flights will be flown. The first of these readiness flights, named Ares I-X, is scheduled to be launched in April 2009. The NASA Glenn Research Center is responsible for the design, manufacture, test and analysis of the Ares I-X upper stage simulator (USS) element. As part of the design effort, the structural dynamic response of the Ares I-X launch vehicle to its vibroacoustic flight environments must be analyzed. The launch vehicle will be exposed to extremely high acoustic pressures during its lift-off and aerodynamic stages of flight. This in turn will cause high levels of random vibration on the vehicle’s outer surface that will be transmitted to its interior. Critical flight equipment, such as its avionics and flight guidance components are susceptible to damage from this excitation. This study addresses the modelling, analysis and predictions from examining the structural dynamic response of the Ares I-X upper stage to its vibroacoustic excitations. A statistical energy analysis (SEA) model was used to predict the high frequency response of the vehicle at locations of interest. Key to this study was the definition of the excitation fields corresponding to lift off acoustics and the unsteady aerodynamic pressure fluctuations during flight. The predicted results will be used by the Ares I-X Project to verify the flight qualification status of the Ares I-X upper stage components.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p177.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p123" class="affilation"></a>Vibroacoustic Response of the NASA ACTS Spacecraft Antenna to Launch Acoustic Excitation</h2>
<h3>Jeffrey M. Larko (1), Vincent Cotoni (2)</h3>
<p class="affilation">(1) NASA Glenn Research Center, 21000 Brookpark Road, Cleveland OH 44135, USA (2) ESI-US R&D, 12555 High Bluff Drive, Suite 250, San Diego, CA 92130, USA</p>
<p><b>ABSTRACT</b><br>
The Advanced Communications Technology Satellite was an experimental NASA satellite launched from the Space Shuttle Discovery. As part of the ground test program, the satellite’s large, parabolic reflector antennas were exposed to a reverberant acoustic loading to simulate the launch acoustics in the Shuttle payload bay. This paper describes the modelling and analysis of the dynamic response of these large, composite spacecraft antenna structure subjected to a diffuse acoustic field excitation. Due to the broad frequency range of the excitation, different models were created to make predictions in the various frequency regimes of interest: a statistical energy analysis (SEA) model to capture the high frequency response and a hybrid finite element-statistical energy (hybrid FE-SEA) model for the low to mid-frequency responses. The strengths and limitations of each of the analytical techniques are discussed. The predictions are then compared to the measured acoustic test data and to a boundary element (BEM) model to evaluation the performance of the hybrid techniques.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p123.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p539" class="affilation"></a>MSL Pyroshock Development Test Program for Shock Mitigation</h2>
<h3>Juan Pablo Fernández</h3>
<p class="affilation">Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., MS 157-410, Pasadena, CA 91109-8099, USA</p>
<p><b>ABSTRACT</b><br>
The Mars Science Laboratory (MSL) is a NASA rover scheduled to launch in December 2009 and perform a precision landing on Mars in October 2010. This rover will be three times as heavy and twice the width of the Mars Exploration Rovers (MERs) that landed in 2004. The MSL Spacecraft makes extensive use of pyrotechnic devices to enable missioncritical separation and deployment events. Several of the devices employed generate high shock levels that are potentially damaging to shock-sensitive equipment on the spacecraft. Early on in the project, it became critical for mission success to characterize the shock-induced environments and minimize their impact on sensitive hardware. This paper describes the JPL development test program undertaken to investigate shock mitigation and isolation techniques, and ultimately to refine early pyroshock environmental estimates. Testing consisted of live-firings of pyrotechnic devices, mainly 5/8" separation nuts, attached to various development test hardware. Multiple firings were performed of each test configuration to assess firing-to-firing repeatability. Candidate isolation techniques were screened using a simple 3 ft. by 3 ft. by .60 in. Aluminum square plate. The effectiveness of select isolation techniques were then verified on high-fidelity mockup hardware of the Rover top deck and instrument panel, and of a Descent Stage (DS) hex and outrigger panel. Isolation approaches at the box level and device level were explored. Through a combination of source mitigation and victim isolation, order-of-magnitude reductions of the shock levels were achieved at key locations. As a result, critical telecommunications equipment with known susceptibility to shock levels as low as 500 G Shock Response Spectrum (SRS) did not need to be re-designed, and various other heritage hardware avoided having to be re-qualified to higher shock levels. By addressing pyroshock issues early on in the program, the MSL project avoided unnecessary rework of hardware and attendant schedule delays.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p539.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p614" class="affilation"></a>Virtual Vibration Test and Verification for the Satellite</h2>
<h3>Shu-hong Xiang, Chuang Liu, Tingfei Yan</h3>
<p class="affilation">Beijing Institute of Spacecraft Environment Engineering, Yard 1 Road Huayanbeili Chaoyang Beijing 100029, China</p>
<p><b>ABSTRACT</b><br>
The vibration test is import in the satellite development. The virtual vibration test can prefigure the test result. It can be used for the test design and the structure modification of the satellite Firstly, the finite element model (FEM) is established for the shaker by the stepping up method. The method solved the problem that is the building FEM of the shaker’s complex structure and the computer simulate analysis of dynamic response. The shaker has been separated into several substructures. The FEM is established and the model test is made for every substructure. The FEM is modified by the experimental data. The shaker’s FEM is constructed via the modified substructures. Secondly, the virtual vibration test is realized based the virtual simulate and prefigurative technology. The computer simulation of shaker and the realization of vibration control test are solved by this technology. Though the numerical force spectrum at the exciting points, the simulate test is completed with table-board control. Finally, connecting the FEM of some satellite, a virtual vibration test of shaker and satellite is made. The virtual vibration platform for satellite has been built. The numerical results agree well with those from the true vibration test.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p614.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p393" class="affilation"></a>Study on Numerical Vibro-Acoustic Analysis of Spacecrafts</h2>
<h3>Takashi Takahashi, Keiichi Murakami, Takashi Aoyama, Hideaki Aiso</h3>
<p class="affilation">Institute of Space Technology and Aeronautics, Japan Aerospace Exploration Agency, 7-44-1 Jindaiji-Higashimachi, Chofu, Tokyo, 182-8522, Japan</p>
<p><b>ABSTRACT</b><br>
The objective of this paper is to examine some limitations in vibro-acoustic analysis using the finite element method (FEM), and to investigate the applicability of a novel deterministic approach called the wave base method (WBM) to steady-state vibro-acoustic analysis of spacecraft inside a payload fairing during the lift-off. It is pointed out that the limitations in vibro-acoustic analysis using the FEM are mainly on numerical dispersion error and on model size. A structural FEM simulation using the different sound field models shows that a deterministic approach as an alternative to the FEM is necessary for the coupled vibro-acoustic analysis with the wide frequency range. Next, in order to overcome the limitations of the FEM, the applicability of the WBM to steady-state vibro-acoustic analysis of spacecraft is investigated. From a simulation example, local structural responses can be obtained due to its deterministic characteristic, and the coupled vibro-acoustic analysis of spacecrafts can be performed easily and properly. From the WBM formulation and numerical simulation, it can be stated that the WBM is a quite practical approach, and has high potential for the vibro-acoustic analysis with the wide frequency range.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p393.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p533" class="affilation"></a>Development of a General Periodic SEA Subsystem for Modeling the Vibro-Acoustic Response of Complex Structures</h2>
<h3>V. Cotoni (1), R. Langley (2)</h3>
<p class="affilation">(1) ESI Group, 12555 High Bluff Dr, San Diego, CA 92014, USA (2) University of Cambridge, Trumpington St, Cambridge CB21PZ, UK</p>
<p><b>ABSTRACT</b><br>
Statistical Energy Analysis (SEA) has been used extensively to model the vibro-acoustic response of launch vehicles and payloads since the early 1960s. Modern SEA codes contain a large library of different subsystems that can accurately account for complicating effects such as ribs, curvature, lamination and pressurization. However, applications are sometimes encountered where a standard subsystem does not exist for a given type of construction. In some instances it is possible to estimate or update the subsystem properties from test or local FE models; however, the development of a generic subsystem that can include an arbitrarily complicated section is desirable. This paper discusses the development of a general periodic subsystem based on the use of periodic structure theory. A finite element model is created of a unit cell and analytical expressions are used to obtain the SEA properties of a larger panel comprised of a large number of such cells. The approach provides an efficient and accurate way to model arbitrarily complex sections in SEA that are difficult to model using traditional formulations. For launch vehicle applications the approach is particularly useful for modelling advanced laminate and isogrid constructions.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p533.pdf" target="_blank"> Full Paper</a></p>
<hr>
<h2><a name="p818" class="affilation"></a>Simulation of Mechanical Systems in Loading with Broadband Random Axitation</h2>
<h3>Igor N. Ovchinnikov</h3>
<p class="affilation">Bauman Moscow State Technical University, 2-nd Baumanskaya, 5, 105005, Moscow, Russia</p>
<p><b>ABSTRACT</b><br>
In the report the modelling by a Galerckin method of dynamics of a console beam is submitted at cinematic loading by broadband random vibration. The loading spectrum extends with the certain interval, i.e. the operation similar to experimental definition of frequency characteristics is carried out. At scope by a loading spectrum “n” of own frequencies of a beam vibrospeed and tension in dangerous section accept extreme meanings.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p818.pdf" target="_blank"> Full Paper</a></p>
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<h2><a name="p147" class="affilation"></a>The Dynamic Analysis of a Building Structure - Acoustic Volume Interaction System Excited by Human Footfall Impacts</h2>
<h3>Jing Tang Xing, Ye Ping Xiong, Mingyi Tan</h3>
<p class="affilation">School of Engineering Sciences, University of Southampton, Southampton SO17 1BJ, England</p>
<p><b>ABSTRACT</b><br>
A numerical model is developed using a mixed finite element method to simulate building structure - acoustic volume interaction systems excited by human walking impacts. The pressure in the air volume and the displacement in the structure are chosen as fundamental variables to describe structure - air interaction dynamics. The governing equations and corresponding variational formulation are presented. Based on available experimental results on the footfall load history, an approximate load function is proposed to simulate the measured dynamic footfall load as a moving load with a walking speed and dynamically applied to each foot contact point. A simple example is presented to illustrate the method which reveals the mechanism of low-frequency vibration produced by human walking impacts using an air-structure interaction method. The benefits of the proposed method are summarized to provide a guideline using the method to practical house designs.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p147.pdf" target="_blank"> Full Paper</a></p>
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<h2><a name="p368" class="affilation"></a>Measurements of Viscoelastic Properties of Concrete Structure Using Beam Transfer Function Method</h2>
<h3>Junhong Park (1), Seung Joon Kim (1), Young Jeong (2), Jin Yong Jeon (2)</h3>
<p class="affilation">(1) School of Mechanical Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul, 133-791, Korea (2) Department of Architectural Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul, 133-791, Korea</p>
<p><b>ABSTRACT</b><br>
Flexural wave propagation characteristics influence the impact noise generation of concrete structures found in apartment floors. The flexural vibration of the concrete structure is affected from its dynamic properties. The purpose of this study is to propose an experimental method of measuring the dynamic characteristics of concrete structures. Using the beam transfer function method, the flexural wave speeds, bending stiffness and their loss factors are measured from which the vibration dissipation capabilities are investigated. Various concrete beam structures were built for measurement. The parameters that have impact on the experimental results were identified. The dynamic stiffness of a concrete structure was determined by its components, and remains constant under the frequency range of interest. The structural loss factor which was similar to each other for various concrete beams was much smaller compared to those of typical polymeric materials. Since the damping in the concrete structure is small, the damping treatments should be a most effective method to reduce vibration and noise generation.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p368.pdf" target="_blank"> Full Paper</a></p>
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<h2><a name="p551" class="affilation"></a>Vibration Control of Buildings: Case Studies</h2>
<h3>Maud Serra</h3>
<p class="affilation">Peutz & Associates acoustical consultants, 34 rue de Paradis, F75010 Paris, France</p>
<p><b>ABSTRACT</b><br>
Buildings erected close to rail lines (e.g. railways, streetcars and subways) usually are subjected to both sound and vibration. While the former is quite well known and has been covered in the relevant regulations in force, the latter is not as well mastered. After a brief description of the relevant regulations and standards in force in France, the present paper submits an insight of such problems, from the definition of noise and vibration objectives to the elaboration of vibration control strategies, especially on the building. Then, it looks into the relevant kind of prescriptions and especially looks into the typical site supervision that is needed on such projects, from material approval to site visits, before covering the commissioning measurements. Those various stages are illustrated using a couple of case studies on office buildings. The main conclusion, based on sheer experience, is that both material approval and a vigilant site supervision are needed for a satisfactory result to be obtained.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p551.pdf" target="_blank"> Full Paper</a></p>
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<h2><a name="p488" class="affilation"></a>Two Modelling Approaches for Periodic Rib-Stiffend Plates Typcial of Floor Assemblies</h2>
<h3>Trevor R. T. Nightingale (1), Ivan Bosmans (2)</h3>
<p class="affilation">(1) National Research Council Canada, Institute for Research in Construction, Building M-27, 1200 Montreal Road, Ottawa, Ontario, K1A 0R6 Canada (2) LMS International, Engineering Services Division, Interleuvenlaan 68, B-3001 Leuven, Belgium</p>
<p><b>ABSTRACT</b><br>
Floors in lightweight framed construction are periodic orthotropic point connected plate-rib structures formed from orthotropic wood sheathing and a series of joists spaced at a regular interval. These structures are driven into motion by point excitations from people walking, dropping objects, etc. To accurately estimate flanking involving mechanical excitation one must predict the injected power using the mobility of the source and structure, and then estimate the resulting vibration distribution across the periodic floor structure. By examining two prediction approaches - SEA and an analytical solution for an assembly of finite sized plates - this paper shows that the more complex analytic solution gives a much better estimate of the vibration distribution, and is the only method capable of capturing the spatial dependence of the drive-point mobility. The analytic model is then used to identify the parameters of a joist floor that should be considered when designing a floor that has good low frequency impact sound insulation.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p488.pdf" target="_blank"> Full Paper</a></p>
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<h2><a name="p337" class="affilation"></a>Control of Radiated Noise from Ship’s Cabin Floor</h2>
<h3>Won-Ho Joo (1), Sung-Hoon Kim (1), Jong-Gug Bae (1), Suk-Yoon Hong (2)</h3>
<p class="affilation">(1) Hyundai Heavy Industries Co. Ltd, 1 Jeonha-Dong, Dong-Gu, Ulsan, 682-792, Korea (2) Department of Naval Architecture and Ocean Engineering, College of Engineering, Seoul National, University San 56-1, Sillim-dong, Kwanak-Gu, Seoul, 151-744, Korea</p>
<p><b>ABSTRACT</b><br>
In order to develop the noise control design for a ship’s cabin, a series of acoustic tests were carried out by using large scale noise test facilities such as two reverberation rooms and deckhouse mock-up. From the tests, it was found out that the combined noise level of a cabin could be dominated by the radiated noise from the stiffened steel plate system in combination with deck covering and fire-protection insulation, so called the deck floor. In this paper, the dynamic characteristics of a deck floor were fully identified through the structure-borne noise transmission test in the deckhouse mock-up. Based on the results, a variety of countermeasures, such as constrained layer damping treatment, multi-layer floating floor having a visco-elastic damping layer and dynamic absorber, etc., were applied to reduce the radiated noise from the deck floor. The results were compared with those of numerical simulations by using the spectral finite element method. Through a series of numerical simulations and structure-borne noise transmission tests, it was found out that the noise reduction for ship’s cabin floor can be greatly enhanced over the entire frequency range if the visco-elastic deck covering is installed between the deck floor and floating floor.</p>
<p class="affilation"><img src="../images/pdfview_small.gif" alt="PDF" border="0" style="width: 28px; height: 31px;"><a href="papers/p337.pdf" target="_blank"> Full Paper</a></p>
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