Showing papers in "Applied Acoustics in 2000"

TL;DR: In this article, the vibration of a functionally graded cylindrical shell made up of stainless steel and zirconia is studied and its properties are graded in the thickness direction of the shell according to volume fraction power law distribution.

TL;DR: In this paper, two methods for measuring scattering coefficients of rough surfaces are described and the results of the reverberation chamber measurements are scattering coefficients for random sound incidence are discussed and experimental results are obtained by scale model measurements.

TL;DR: In this paper, the authors used statistical energy analysis (SEA) to model sound transmission through double leaf partitions and found that the best SEA model depends on the frequency range considered and the method of construction.

TL;DR: In this article, some heuristic formulae are proposed which take into account the modifications of the physical parameters (porosity, resistivity, tortuosity and shape factors) which enter the standard equivalent fluid model.

TL;DR: In this paper, a wave approach is introduced to predict the natural frequencies of finite length circular cylindrical shells with different boundary conditions without simplifying the equations of motion, and the results obtained compare favourably with those obtained using the finite element method.

TL;DR: In this article, structural coupling is examined in more detail and two theories are presented: one is appropriate where the connection behaves as a series of points and the other one is a continuous line, where a half bending wavelength on the plate fitted between the nails or screws that form the coupling.

TL;DR: In this article, the effectiveness of a floating slab track system to stationary harmonic loads and moving harmonic loads is investigated by using the receptance method, and the results show that the floating slab tracker system is effective in reducing the forces transmitted at frequencies above the designed frequency compared to the fixed slab tracker.

TL;DR: In this article, the authors compared the performance of different methods of measuring the complex Poisson's ratio of viscoelastic materials as a function of frequency with special respect to the accuracy of determining the relevant loss factor.

TL;DR: In this article, the authors describe a study to assess the size and nature of ground-borne vibrations produced when vehicles pass over these profiles and in some cases they can reach perceptible levels in adjacent buildings and highlight the need to carefully consider the siting of these profiles especially on soft soils.

TL;DR: The C. Zwikker and C. W. Kosten model for sound propagation through porous flexible media is used for numerical calculations of some intrinsic characteristics of nonwoven fiberwebs yielding the highest sound absorption coefficients in the audible frequency range as mentioned in this paper.

TL;DR: Theoretical and experimental progress on the source descriptor is reviewed in this paper, where it is observed that the uncoupled component source descriptors can establish the bandwidth and dominant components of excitation.

TL;DR: In this paper, the pseudo-forces method is used to characterize structure-borne sound sources, where the internal excitation in a source component is reproduced by fictitious forces on the outer surface.

TL;DR: In this article, a computer-aided-engineering (CAE) method is used for noise reduction in a truck cab interior using finite element (FE) and boundary element method (BEM).

TL;DR: In this article, the radiated noise contributions of automotive body panels to the interior sound pressure levels are modeled using an approximate spectral formulation that applies the theoretical interior acoustic sensitivity terms derived from a finite element model and measured spatial-averaged structural-acoustic spectra.

TL;DR: In this article, the torsional dynamic characteristics of an automotive clutch are simulated by five lumped parameter linear or nonlinear models, each nonlinear model includes visco-elastic and dry friction elements.

TL;DR: In this paper, a novel method of measuring the normal specific acoustic impedance has been tested in laboratory experiments and applied in-situ in order to calculate the corresponding absorption coefficients of the surface.

TL;DR: In this article, the authors discuss the application of diffusors in music production rooms such as performance facilities, and music reproduction rooms, such as recording studios, and present case studies from different room types.

TL;DR: In this paper, a force analysis technique called "Force Analysis Technique" (FAT) is proposed, which is based on the computation of the force distribution, the second member of the equation of motion which is discretized by a finite difference scheme.

TL;DR: In this paper, the authors present a technique of measurement based on particle velocity measurement by laser Doppler anemometry (L.D.A.) together with microphonic acoustic pressure measurement.

TL;DR: In this article, a hybrid approach for prediction of noise radiation from engine exhaust systems is presented, which combines the time domain analysis of the engine and the frequency domain analysis on the muffler.

TL;DR: In this article, the propagation of sound emitted by aircraft close to the ground was investigated in the framework of acoustic and seismic monitoring of airports for verifying disarmament or peace-keeping agreements, the propagation time of the sound from the source to the different sensors was determined by a cross correlation of the signals with a time resolution of 0.18 and 0.36 ms.

TL;DR: In this article, a selection of advanced acoustic sensor systems for military use is presented along with the necessary background information, and realistic limits for various parameters are given based on field work, which enables the reader to understand design characteristics for acoustic sensor system and to predict their performance under given conditions.

TL;DR: In this article, a theoretical model to predict bending wave transmission through parallel plates connected by a resilient line is presented, based on the interaction of semi-infinite plates intersecting along an infinite boundary.

TL;DR: In this paper, a classical approach to theoretically calculate the transmission loss of multilayered walls is described, based on the compilation of the impedances encountered by an acoustic wave as it propagates through the wall.

TL;DR: In this paper, the acoustic radiation power of a thin annular plate, clamped with both its edges into a planar rigid and infinite baffle, has been analyzed and some processes sinusoidally varying in time have been considered.

TL;DR: In this paper, preliminary experimental results are presented for low frequency data of sound sources, acoustic materials and construction elements, and a detailed discussion of different approaches and procedures in other test laboratories is presented.

TL;DR: In this article, the structural intensity vectors and rms velocity distributions of a simply-supported thin finite plate have been determined using finite element harmonic response analysis for three excitation conditions: point force excitation with an attached damper but without structural damping, point forces excitation over a finite area with structural stiffening, and force excitations over a fixed area with stiffening.

TL;DR: In this paper, a hybrid passive/active system was designed and implemented to control the noise radiated by a small generator by enclosing the generator with a close-fitting, leaky, rectangular box.

TL;DR: In this article, the results from linear acoustic theory were compared with those obtained from a full non-linear calculation validated against engine test experiments, and the results indicated that good qualitative agreement may be attained in general, but some differences associated with nonlinear effects can appear.