Journal of Computational Acoustics最新文献

{"title":"FAST ITERATION ALGORITHM FOR INTEGRAL EQUATIONS OF THE FIRST KIND ARISING IN 2D DIFFRACTION BY SOFT OBSTACLES","authors":"A. Scalia, V. Popuzin, M. Pennisi","doi":"10.1142/S0218396X13500070","DOIUrl":"https://doi.org/10.1142/S0218396X13500070","url":null,"abstract":"We propose a new iteration numerical algorithm to solve boundary integral equations of the first kind arising in the 2D scattering by soft obstacles. The main idea is to operate on each iteration step with an integral equation, which has a convolution kernel, by changing the full kernel with a special averaging procedure. The practical convergence of the algorithm is demonstrated by some examples for three different geometries. If M is the number of iterations then the computational cost of the algorithm is MNlog(N).","PeriodicalId":54860,"journal":{"name":"Journal of Computational Acoustics","volume":"21 1","pages":"1350007"},"PeriodicalIF":0.0,"publicationDate":"2013-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1142/S0218396X13500070","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64073330","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"ANALYSIS OF ALTERNATIVE METHODS FOR IMPULSE RESPONSE FUNCTIONS BASED ON SIGNAL-TO-NOISE RATIO ENHANCEMENT AND COMPLETENESS OF SOURCE SIGNAL RECONSTRUCTION USING PASSIVE TIME REVERSAL","authors":"Y. Hsieh, G. Too","doi":"10.1142/S0218396X13500082","DOIUrl":"https://doi.org/10.1142/S0218396X13500082","url":null,"abstract":"Noise reduction and signal separation are important functions of acoustic signal processing. This study presents a detailed analysis for designing an acoustic signal processing procedure based on the time-reversal method. For some applications, setting transducers to retransmit at source locations is impracticable. Modeling a wave propagation path between two points using impulse response function is one way to overcome this limitation. This paper introduces alternative methods to calculate impulse response function, including an adaptive digital filter, deconvolution with singular value decomposition and Tikhonov regularization, and correlation. A discussion is also provided on the applicable frequency range and anti-noise ability of the impulse response functions obtained by all three techniques through simulation, and subsequently applies them to the designed time reversal process to enhance the signal-to-noise ratio (SNR) and restore source signals through experimentation. The conclusions of this study are given based on the level of accuracy using the SNR and correlation coefficient as indicators, and the computation time required by alternative methods is also an important factor to be discussed for real-time system design. Results prove that the proposed passive time reversal process is capable of enhancing the SNR and restoring the source signal. The alternative methods of calculating the impulse response function offer various advantages, and should be selected according to the application. If the time-cost is the first consideration and there is no dominant noise source, then correlation is the best choice for calculating impulse response function. If completeness of the reconstructed signal is the key point, the optimal deconvolution process is appropriate. If noise reduction is the highest priority in extracting a useful signal from noisy environments while ensuring acceptable restoration capability and computation time, an adaptive digital filter is suitable.","PeriodicalId":54860,"journal":{"name":"Journal of Computational Acoustics","volume":"21 1","pages":"1350008"},"PeriodicalIF":0.0,"publicationDate":"2013-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1142/S0218396X13500082","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64073372","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"PARAMETRIC STUDY OF PROPELLER TONE NOISE DUE TO NONUNIFORM FLOWS","authors":"Q. Zhou, J. Xie, B. Fang, Y. Pan","doi":"10.1142/S0218396X13500057","DOIUrl":"https://doi.org/10.1142/S0218396X13500057","url":null,"abstract":"This paper investigates the tone noise generation by submarine propellers operating in nonuniform flows. A frequency domain numerical approach is proposed. The flow nonuniformities due to submarine wakes are obtained from Computational Fluid Dynamics method. The results show that the velocity field and its harmonics depend greatly on the hull geometry and its appendages. The prediction of the radiated far-field tone noise due to a seven-bladed, highly-skewed propeller has been performed. A prediction of the acoustic pressure level for various blade skew angles shows that the tone noise reduction amount increases as the inflow velocity increases. The predicted dependence of the radiated noise on the inflow velocity, propeller diameter and blade rotational speed shows that the mean square sound pressure at the first-order blade passing frequency varies as the 3.3 power of the characteristic inflow velocity, the third power of the propeller diameter and with the second power of the blade rotational speed. Effects of blade number on the propeller tone noise directivity are also discussed, which shows that the characteristic coupling order between the main inflow harmonic and the rotating blades is the key to determine the directivity pattern.","PeriodicalId":54860,"journal":{"name":"Journal of Computational Acoustics","volume":"21 1","pages":"1350005"},"PeriodicalIF":0.0,"publicationDate":"2013-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1142/S0218396X13500057","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64073446","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"ACTIVE CONTROL OF A MACHINE SUSPENSION SYSTEM SUPPORTED ON A CYLINDRICAL SHELL","authors":"X. Liu, G. Jin, Y. Wang, Yue Shi, X. Feng","doi":"10.1142/S0218396X13500124","DOIUrl":"https://doi.org/10.1142/S0218396X13500124","url":null,"abstract":"A numerical study on the active control of a machine suspension system supported on a cylindrical shell aiming to reduce the sound radiation is presented in this paper. In this system, a rigid-body machine is supported on a simply-supported elastic cylindrical shell through four active isolators. A theoretical model is employed and four types of active control strategies including kinetic energy minimization strategy, power flow minimization strategy, squared acceleration minimization strategy and acoustic power minimization strategy are considered, with corresponding active control force obtained by linear quadratic optimal method. Numerical simulations are conducted and detailed results were presented. Active control performance under these four control strategies is compared and analyzed in terms of radiated sound power, and the effect of the number of active actuators is discussed by numerical analysis. The results show that acoustic power minimization strategy has the best performance to reduce the sound power radiated from supporting shell in general. Through numerical simulations, some comprehensive design principles of active control system are discussed at the end.","PeriodicalId":54860,"journal":{"name":"Journal of Computational Acoustics","volume":"21 1","pages":"1350012"},"PeriodicalIF":0.0,"publicationDate":"2013-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1142/S0218396X13500124","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64073597","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"NONLINEAR PROPAGATION OF SOUND EMITTED BY HIGH SPEED WAVE PACKETS","authors":"E. Avital, R. E. Musafir, T. Korakianitis","doi":"10.1142/S0218396X12500270","DOIUrl":"https://doi.org/10.1142/S0218396X12500270","url":null,"abstract":"Jet's sound-field emitted by a large scale source modeled as a wave packet is considered. Attention is given to nonlinear propagation effects caused by the source's supersonic Mach number and high amplitude. The approach of the Westervelt equation is adapted to derive a new set of weakly nonlinear sound propagation equations. An optimized Lax–Wendorff scheme is proposed for the newly derived equations. It is shown that these equations can be simulated using a time step close to the CFL limit even for high amplitudes unlike the conventional finite-difference simulation approach of the Westervelt equation. Two- and three-dimensional sound propagations were simulated for symmetric and asymmetric supersonic wave packets. It is seen that nonlinearity in the sound field is affected by the wave packet form, an effect that cannot be captured by a 1D propagation equation. High skewness in the pressure fluctuation and its time derivative were found near the Mach direction, showing crackle-like features. Pressure time history and frequency spectra are also investigated.","PeriodicalId":54860,"journal":{"name":"Journal of Computational Acoustics","volume":"21 1","pages":"1250027"},"PeriodicalIF":0.0,"publicationDate":"2013-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1142/S0218396X12500270","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64073083","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"ANALYTICAL TIME DOMAIN NORMAL MODE SOLUTION OF AN ACOUSTIC WAVEGUIDE WITH PERFECTLY REFLECTING WALLS","authors":"H. O. Sertlek, S. Aksoy","doi":"10.1142/S0218396X12500269","DOIUrl":"https://doi.org/10.1142/S0218396X12500269","url":null,"abstract":"Solution of wide-band underwater acoustic problems with the classical Normal Mode method in the frequency domain needs to solve the problem repeating for every frequency component of the wide-band source signal. In this paper, a direct and causal analytical Time Domain Normal Mode Method is presented for arbitrary time-dependent acoustic sources for a single layered isovelocity waveguide. An incomplete separation of variables technique is used to solve the inhomogeneous wave equation, directly in the time domain. Therefore, it becomes possible to calculate the time domain acoustic pressure in a single run.","PeriodicalId":54860,"journal":{"name":"Journal of Computational Acoustics","volume":"21 1","pages":"1250026"},"PeriodicalIF":0.0,"publicationDate":"2013-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1142/S0218396X12500269","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64073025","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"NUMERICAL SIMULATION OF FIBER-OPTIC PHOTOACOUSTIC GENERATOR USING NANOCOMPOSITE MATERIAL","authors":"Ye Tian, N. Wu, K. Sun, X. Zou, Xingwei Wang","doi":"10.1142/S0218396X13500021","DOIUrl":"https://doi.org/10.1142/S0218396X13500021","url":null,"abstract":"Photoacoustic generation using an optical fiber is a promising approach to meet the challenges in most advanced ultrasonic non-destructive testing (NDT) applications. The energy-absorption layer coated on the fiber endface plays an important role in converting the laser energy into heat and exciting the acoustic wave. The selection of the absorption material and the optimization of the structure dimension are the keys for achieving high energy-conversion efficiency. A 2D-axisymmetric finite element analysis (FEA) model was established to simulate the photoacoustic generation process using a newly developed absorption material, polydimethylsiloxane/gold nanoparticle (PDMS/Au NPs) nanocomposites, with different thicknesses and laser pulse durations. The experimental results obtained using a similar set-up show a similar trend predicted by this FEA simulation. The FEA results provide practical clues to the design of the fiber-optic photoacoustic generator.","PeriodicalId":54860,"journal":{"name":"Journal of Computational Acoustics","volume":"28 1","pages":"1350002"},"PeriodicalIF":0.0,"publicationDate":"2013-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1142/S0218396X13500021","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64073242","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A COMPARISON OF TRANSIENT INFINITE ELEMENTS AND TRANSIENT KIRCHHOFF INTEGRAL METHODS FOR FAR FIELD ACOUSTIC ANALYSIS","authors":"T. Walsh, Andrea Nicole Ames Jones, M. Bhardwaj, C. Dohrmann, G. Reese, Riley Wilson","doi":"10.1142/S0218396X13500069","DOIUrl":"https://doi.org/10.1142/S0218396X13500069","url":null,"abstract":"Finite element analysis of transient acoustic phenomena on unbounded exterior domains is very common in engineering analysis. In these problems there is a common need to compute the acoustic pressure at points outside of the acoustic mesh, since meshing to points of interest is impractical in many scenarios. In aeroacoustic calculations, for example, the acoustic pressure may be required at tens or hundreds of meters from the structure. In these cases, a method is needed for post-processing the acoustic results to compute the response at far-field points. In this paper, we compare two methods for computing far-field acoustic pressures, one derived directly from the infinite element solution, and the other from the transient version of the Kirchhoff integral. We show that the infinite element approach alleviates the large storage requirements that are typical of Kirchhoff integral and related procedures, and also does not suffer from loss of accuracy that is an inherent part of computing numerical derivatives in the Kirchhoff integral. In order to further speed up and streamline the process of computing the acoustic response at points outside of the mesh, we also address the nonlinear iterative procedure needed for locating parametric coordinates within the host infinite element of far-field points, the parallelization of the overall process, linear solver requirements, and system stability considerations.","PeriodicalId":54860,"journal":{"name":"Journal of Computational Acoustics","volume":"21 1","pages":"1350006"},"PeriodicalIF":0.0,"publicationDate":"2013-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1142/S0218396X13500069","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64073265","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A COMPARISON OF ONE- AND TWO-SIDED KRYLOV–ARNOLDI PROJECTION METHODS FOR FULLY COUPLED, DAMPED STRUCTURAL-ACOUSTIC ANALYSIS","authors":"R. S. Puri, D. Morrey","doi":"10.1142/S0218396X13500045","DOIUrl":"https://doi.org/10.1142/S0218396X13500045","url":null,"abstract":"The two-sided second-order Arnoldi algorithm is used to generate a reduced order model of two test cases of fully coupled, acoustic interior cavities, backed by flexible structural systems with damping. The reduced order model is obtained by applying a Galerkin–Petrov projection of the coupled system matrices, from a higher dimensional subspace to a lower dimensional subspace, whilst preserving the low frequency moments of the coupled system. The basis vectors for projection are computed efficiently using a two-sided second-order Arnoldi algorithm, which generates an orthogonal basis for the second-order Krylov subspace containing moments of the original higher dimensional system. The first model is an ABAQUS benchmark problem: a 2D, point loaded, water filled cavity. The second model is a cylindrical air-filled cavity, with clamped ends and a load normal to its curved surface. The computational efficiency, error and convergence are analyzed, and the two-sided second-order Arnoldi method shows better efficiency and performance than the one-sided Arnoldi technique, whilst also preserving the second-order structure of the original problem.","PeriodicalId":54860,"journal":{"name":"Journal of Computational Acoustics","volume":"5 1","pages":"1350004"},"PeriodicalIF":0.0,"publicationDate":"2013-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1142/S0218396X13500045","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64073346","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"LAMB WAVES IN A POROELASTIC PLATE","authors":"R. Gilbert, Doo-sung Lee, M. Y. Ou","doi":"10.1142/S0218396X1350001X","DOIUrl":"https://doi.org/10.1142/S0218396X1350001X","url":null,"abstract":"In this paper we consider the propagation of Lamb waves in a poroelastic plate containing a linear crack, the special case where the surface of the plate is unloaded, by employing the Wiener-Hopf technique. The problem we solve here is a mathematically interesting toy problem. Physically speaking the more reasonable problem would be to consider there to be fluid pressure on both sides of the plate. This problem can be solved using the solution we derive here and will be presented in a subsequent work. Also dealt in this paper are the characteristic equations for a viscous fluid Biot systems and the orthogonality relations for a free boundary poroelastic slab.","PeriodicalId":54860,"journal":{"name":"Journal of Computational Acoustics","volume":"21 1","pages":"1350001"},"PeriodicalIF":0.0,"publicationDate":"2013-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1142/S0218396X1350001X","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64073099","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}