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Integration of Deep Learning with Vibration-Based Identification Method J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2024-02-28 Nan Li, Dingfu Zhou, Fan Lu, Fan Bai, Kaiqiang Wang, Weiping Wang, Xiaoyan Hu, Liang Meng, Fusheng Sui
The vibration-based identification method has long been used as an alternative to mechanical tests for material characterization. Its non-destructive nature, high efficiency in parameter identification of anisotropic materials and its ability to achieve structure-level homogenization make it very attractive for both academic community and industry. Due to the absence of explicit mapping from the result
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Study on Nonlinear Acoustic Waves in Stepped Acoustic Resonators J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2024-02-16 Yanan Yu, Qi Chen, Wen He, Jie Zhou
The problem of investigating the nonlinear acoustic waves in stepped acoustic resonators is treated theoretically. A perturbation scheme that combines the method of multi-scale expansion yields a set of coupled nonlinear ordinary differential equations for deriving an analytical model to describe the resonant oscillations. The nonlinear sound pressure in stepped resonator is predicted with accuracy
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Virtual Rotating Array for Near-Field Localization of Rotating Sound Sources J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2024-02-09 Jianixong Feng, Yangfan Liu, Kai Ming Li
In this study, a more efficient time domain (TD) virtual rotating array (VRA) method is proposed that employs a zeroth-order interpolation scheme. The interpolation of sound fields in the receiver plane using only the nearest microphone at each time step improves the efficiency of the entire process. Additionally, the VRA method is demonstrated to function well with near-field acoustic holography for
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Non-Synchronous Measurements Acoustic Imaging Method Based on Capped Nuclear Norm Minimization J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2024-02-02 Juan Wei, Yutao He, Weichen Ning
In this work, the difference convex function based on capped nuclear norm minimization (CNNM-DC) method, a cross-spectral matrix (CSM) completion iterative algorithm with excellent noise immunity, is proposed to realize acoustic imaging of non-synchronous measurements (NSM) under the condition of low signal-to-noise ratio (SNR). Compared with the CSM completion algorithm based on the nuclear norm minimization
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Investigation of Geoacoustic Parameters of Fine-Grained Sediment in the South China Sea Using Sequential Inversion J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2024-02-01 Wang Hao, Rui Duan, Kunde Yang
Broadband signals interacting with deep ocean fine-grained sediment are crucial in shaping the acoustic field of the geometric shadow zone. These signals travel through both the seabed reflected path and the refracted path. In this article, a sequential inversion scheme is employed to estimate the geoacoustic parameters in abyssal clay sediments. This inversion is based on seabed reflection loss data
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Further development of rotating beamforming techniques using asynchronous measurements J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2024-01-24 Bálint Kocsis, Csaba Horváth
When rotating noise sources, such as turbomachinery, are investigated using phased microphone array measurements and beamforming, sidelobes appear on the resulting beamforming maps. Sidelobes can be decreased by increasing the number of microphones. However, if the investigated phenomenon is steady, then there is a cost-effective alternative: performing asynchronous measurements using phased arrays
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Sound Field Reconstruction Using Compressed Separable Projection-Based Equivalent Source Method J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2023-12-22 Yang Shen, Chuan-Xing Bi, Xiao-Zheng Zhang, Yong-Bin Zhang, Rong Zhou
The compressive-equivalent source method (C-ESM) has been developed for the sound field reconstruction by solving the l1 minimization with the predetermined sparsity of the equivalent source strengths. However, the C-ESM would reconstruct the sound field with the error proportional to the measurement noise-related data fidelity constraint that increases with the decrease of the signal-to-noise ratio
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Parameter Identification of a Large-Scale Vibroacoustic Finite Element Model with a One-dimensional Convolutional Neural Network J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2023-12-22 Sophie Cram, Jiale Yu, Marinus Luegmair, Marcus Maeder, Steffen Marburg
Uncertainties are significant in the early vibroacoustic development, e.g., of a car body, to prevent costly modifications close to the start of production. First, engineers must know which uncertain parameters are sensitive: Our previous work identified 170 uncertain parameters being sensitive out of a complex finite element model with 1,300 uncertain parameters – a parameter reduction of approximately
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Coherent Noise Denoising in Beamforming Based on Non-Convex Robust Principal Component Analysis J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2023-12-21 Hongjie Hou, Fangli Ning, Wenxun Li, Qingbo Zhai, Juan Wei, Changqing Wang
Beamforming maps are often seriously impacted by background noise. Background Noise Subtraction (BNS), Eigenvalue Identification and Subtraction (EIS), and Eigenvalue Identification, Organization and Subtraction (EIOS) have been successively proposed and mainly used to reduce the influence of coherent background noise. In this work, an approach of Robust Principal Component Analysis (RPCA) combined
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Deep Learning-Based Dereverberation for Sound Source Localization with Beamforming J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2023-12-19 Qingbo Zhai, Fangli Ning, Hongjie Hou, Juan Wei, Zhaojing Su
In this work, an algorithm that combines deep-learning based dereverberation and beamforming is proposed for sound source localization in the reverberant environment. The contribution is combining deep-learning based dereverberation and beamforming together. Through deep learning, the proposed algorithm can directly achieve dereverberation of the cross-spectral matrix of microphone array measurement
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Revising the Boundary Element Method for Thermoviscous Acoustics: An Iterative Approach via Schur Complement J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2023-12-12 Simone Preuss, Mikkel Paltorp, Alexis Blanc, Vicente Cutanda Henríquez, Steffen Marburg
The Helmholtz equation is a reliable model for acoustics in inviscid fluids. Real fluids, however, experience viscous and thermal dissipation that impact the sound propagation dynamics. The viscothermal losses primarily arise in the boundary region between the fluid and solid, the acoustic boundary layers. To preserve model accuracy for structures housing acoustic cavities of comparable size to the
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A High-Order Immersed Moving Boundary Method using Ghost Points and Characteristics for Acoustics J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2023-12-12 Constance Bocquet, Cyril Desjouy, Gwénaël Gabard
Realistic acoustic problems often involve interactions between arbitrary-shaped moving objects at the interface with a fluid domain. The present work aims at developing numerical methods to take into account moving boundaries for acoustic problems, with a high order of convergence. The reference problem considered in this work is the solution of the non-linear Euler equations by a finite-difference
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Scattering From a Partially Coated Shell Immersed in Water Using a Subtractive Modelling Technique J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2023-12-08 F. Dumortier, V. Meyer, L. Maxit
In this study, we focus on the prediction of the pressure field scattered from an immersed cylindrical shell partially coated by a soft rubber, impacted by an acoustic plane wave. As the coating covers only a partial portion along the circumference of the shell, the considered system is not axisymmetric. As a result, a spectral (Fourier) resolution of the mathematical problem would induce the coupling
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A Fast Multi-Frequency Iterative Acoustic Boundary Element Method Solver Based on a Preconditioned Accelerated Recycling Strategy J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2023-11-29 Dionysios Panagiotopoulos, Wim Desmet, Elke Deckers
Common multi-frequency solution strategies for acoustic systems are either associated with high computational costs or resort to model reduction strategies, which potentially induce considerable approximation errors. In that context, this work proposes a fast multi-frequency solver for acoustic Boundary Element Method (BEM) analyses that combines conventional preconditioners with an accelerated recycling
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Update on the Ivory-billed Woodpecker (Campephilus principalis) Scandal J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2023-11-28 Michael D. Collins
The Ivory-billed Woodpecker (Campephilus principalis) is an elusive bird that has repeatedly been feared extinct only to be rediscovered during the past hundred years. The most recent rediscovery, which took place in Arkansas, was announced in an article that was featured on the cover of Science in 2005. Despite published reports of sightings in Florida and Louisiana in the years that followed, the
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Two-Dimensional Super-Resolution Direction-of-Arrival Estimation for Arbitrary Planar Array Geometries J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2023-11-28 Yang Yang, Yongxin Yang, Zhigang Chu
The two-dimensional grid-free compressed sensing method with planar microphone arrays is expected to achieve super-resolution direction-of-arrival (DOA) estimation for acoustic sources in the hemispherical space in front of array. The existing methods are not yet well compatible with arbitrary planar array geometries. In this paper, we aim to break this limitation and explore a novel method applicable
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A Boundary Element Method for Acoustic Problems in Relative Motion Between Source and Fluid J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2023-11-24 Ruihua Sun, Haijun Wu, Weikang Jiang, Liang Ji, Danwang Li
To calculate the acoustic problems of relative uniform motion between the acoustic source and the fluid, we propose a boundary element method (BEM) strategy that can calculate various forms of relative uniform motion in subsonic conditions in a unified framework and is simple to implement. The acceleration algorithm for the BEM, like the fast multipole method (FMM), in the relative motionless state
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On the Effect of Boundary Conditions on Porous Absorber Characterization and Simulations J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2023-11-07 Mariia Bronzova, Arnaud Bocquillet, Martin Schanz
With the increasing importance of vehicle acoustic comfort, the topics of precise absorber simulation and characterization approaches are coming into forefront. The behavior of widely used porous mass-spring systems, consisting of foams coupled with heavy layers, can be strongly influenced by numerous factors. Among them are boundary conditions between trim materials and exciting structures. This paper
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Bayesian Approach for the In Situ Estimation of the Acoustic Boundary Admittance J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2023-11-04 Jonas M. Schmid, Martin Eser, Steffen Marburg
Interior acoustic problems require accurately representing the boundary conditions of all acoustically interacting surfaces to achieve precise acoustic predictions. The complex-valued boundary admittance fully characterizes these properties. Yet, conventional approaches to determine boundary admittances, such as the impedance tube, have limitations which do not accurately represent real-world conditions
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Estimating the Location of Acoustic Sources with Oceanic Internal Gravity Waves via Frequency-Difference Source Localization J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2023-11-01 John L. Spiesberger, David J. Geroski, David R. Dowling
Frequency-difference source localization (FDSL) is a relatively new method for locating sources emitting acoustic or electromagnetic waves from recorded data. Estimates of location are produced by matching a nonlinear function of the received data with the same nonlinear function of modeled data. This so-called matched-field approach depends on the accuracy of the modeled field. FDSL exhibits less
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Modeling of Complex Moving Sound Sources Using a Cut Finite Element Method Approach J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2023-10-21 Sjoerd van Ophem, Wim Desmet, Elke Deckers
While acoustic analysis with the finite element method is commonly done under the assumption that the source location is stationary, this is not always a valid assumption. This paper derives a method to simulate moving sound sources using an unfitted mesh approach, where the source boundary is described by cutting through elements, known as the cut finite element method (cutFEM). By using such an approach
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Characterization and Optimization of the Angle-Dependent Acoustic Absorption of 2D Infinite Periodic Surfaces of Helmholtz Resonators J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2023-08-08 Diana María Garza-Agudelo, Vicente Cutanda Henríquez, Cheol-Ho Jeong, Peter Risby Andersen
Acoustic metamaterials have emerged as alternative solutions to achieve useful physical effects that differ from the ones obtained with traditional materials. In terms of sound absorption, previous works have addressed their potential as compact surfaces with high performance. Nevertheless, studies on their angle-dependent behavior are scarce. In this work, an analytic model and a numerical model to
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Dynamic Green’s Functions for an Infinite Acoustic Field with Multiple Spheres Subjected to the Robin Boundary Conditions J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2023-08-08 Wei-Ming Lee, Jeng-Tzong Chen
A semi-analytical approach is presented to solve three-dimensional dynamic Green’s function for an infinitely extended acoustic field with multiple spheres subjected to the Robin boundary conditions. The multipole expansions of the acoustic field induced by a time-harmonic point source are expanded with spherical wave functions. As an alternative to the complex addition theorem, the multipole expansion
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Excitation of Scholte Waves at a Sinusoidal Interface of Seafloor J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2023-08-08 Minshuai Liang, Gaokun Yu, Liang Wang, Linhui Peng
In this paper, an elastic seafloor with the sinusoidal interface is modeled to study the effect of the fluctuant interface on Scholte wave excitation. The reflection and transmission coefficients of sound waves are derived from the scattered wave theory to investigate the acoustic field characteristics. In numerical simulations, longitudinally invariant finite element models are constructed to demonstrate
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Geoacoustic Inversion with a Single Vector Sensor and Multichannel Dispersion Curves J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2023-08-04 Alexandre L. Guarino, Kevin B. Smith, Kay L. Gemba, Oleg A. Godin
This paper discusses the value added by using a single vector sensor over a conventional pressure-only hydrophone for geoacoustic inversions. Inversion methods based on genetic algorithms are used to estimate the seabed properties. Synthetic signals of impulsive arrivals first are modeled using KRAKEN and RAM propagation models, each being modified to predict components of the vector field. While KRAKEN
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The Frequency Spectrum of a Harmonically Radiating Monopole Moving along Arbitrary Trajectories with Application to Helical Orbits J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2023-08-04 Martin Ochmann
The sound field of a harmonically radiating monopole moving along arbitrary trajectories in three-dimensional space is studied in the frequency range and represented as a convolution integral in Cartesian coordinates. The observation time of the motion of the source can be finite or infinite. This convolution integral is referred to as the “Cartesian Convolution Integral ” and is applied to point sources
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Efficient Analysis of Energy-Based Surface Contributions for an Entire Acoustic Cavity J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2023-07-12 Caglar Gurbuz, Steffen Marburg
Sound radiation from vibrating structures is a crucial concern in the vehicle design process. One effective tool to recover vibration patterns on surfaces is the surface contribution analysis. Recent implementations, however, focus on surface contributions with respect to single evaluation points. For a contribution analysis regarding an entire volume, the tedious volume integration is required. This
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Poly-Grid Spectral Element Modeling for Wave Propagation in Complex Elastic Media J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2023-05-23 Chang Su, Géza Seriani
Modeling elastic waves in complex media, with varying physical properties, require very accurate algorithms and a great computational effort to avoid nonphysical effects. Among the numerical methods the spectral elements (SEM) have a high precision and ease in modeling such problems and the physical domains can be discretized using very coarse meshes with elements of constant properties. In many cases
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High Resolution Backscattering Acoustic Tomography Method Based on Reverse Time Migration for Arbitrary Wideband Sounding Signal J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2023-03-27 Dmitry Sukhanov, Anzhela Kuzovova
Backscattered wave acoustic tomography using wideband probing signals makes it possible to obtain three-dimensional (3D) images of scattering inhomogeneities. Signal processing based on the reverse time migration (RTM) method allows one to take into account the influence of background refractive obstacles of the medium to minimize distortions of reconstructed tomographic images. We propose a noniterative
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3D Viscoelastic Finite-Difference Analysis of the Monopole Acoustic Logs in Cylindrical Coordinates J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2023-03-27 Yue Pan, Xiao He, Xiuming Wang
In this paper, a model of the heterogeneous anelastic seismic wave problem is proposed in three-dimensional (3D) cylindrical coordinates. We use the velocity-stress formula to describe the realistic attenuation properties of viscoelastic materials, derived from a rheological model of the generalized standard linear solid (GSLS). The equation system is completed by additional equations for the anelastic
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Finite Element Approach for Three-Dimensional Linearized Potential Equation with Application to Muffler Acoustic Attenuation Prediction J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2023-03-27 Yiliang Fan, Zhenlin Ji
In this paper, a three-dimensional finite element method for solving the linearized potential equation (LPE) is implemented to predict the acoustic attenuation performance of mufflers in the presence of nonuniform flow. For accurate physical representations, the porous material is modeled as equivalent fluid with complex speed of sound and density while the background mean flow in fluid domain is captured
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Accurate Broadband Gradient Estimates Enable Local Sensitivity Analysis of Ocean Acoustic Models J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2023-03-25 Michael C. Mortenson, Tracianne B. Neilsen, Mark K. Transtrum, David P. Knobles
Sensitivity analysis is a powerful tool for analyzing multi-parameter models. For example, the Fisher information matrix (FIM) and the Cramér–Rao bound (CRB) involve derivatives of a forward model with respect to parameters. However, these derivatives are difficult to estimate in ocean acoustic models. This work presents a frequency-agnostic methodology for accurately estimating numerical derivatives
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A Frequency-Domain Formulation for Predicting Multi-Frequency Noise Generated by Flows with Periodically Moving Boundaries J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2023-01-19 Zhiteng Zhou, Hongping Wang, Zhenyu Zang, Shizhao Wang
A frequency-domain formulation is proposed to compute the far-field noise generated by flows with periodically oscillating or rotating boundaries. The proposed formulation significantly enhances the efficiency of the frequency-domain method in handling the multi-frequency sources with nonrectilinear motion. The novelty of the proposed method is that the frequency- and time-dependent components of the
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Statistical Characterization of Seismic Signals J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2023-01-05 Costas Smaragdakis, John Mastrokalos, Michael I. Taroudakis
This paper presents a study on the applicability of a method for the statistical characterization of seismic signals which is based on the statistics of their wavelet sub-band coefficients using α stable distributions. The method was originally applied to underwater acoustic signals of the type used in ocean acoustic tomography and seabed classification applications. The same protocol was applied to
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Effects of the Rayleigh Secular Function on Time-Harmonic Asymptotic Solutions Due to Horizontal Vibration Sources J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2022-12-31 Boao Jin, Yan Gao, Zhongkun Jin
The time-harmonic asymptotic solutions due to the surface horizontal vibration sources provide the theoretical basis in the applications of buried object detection. In the integral transformation method, the Rayleigh secular function appears in the denominator of the integrand of the inverse transformation. This leads to the multi-leaf characteristics of the integrand and the asymptotic solution is
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Near Field of the Half-Space Green’s Function J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2022-12-31 Alexey Maksimov
This paper fills the gap in the study of Rayleigh scattering near an interface. The structure of the near-field of the half-space Green’s function is analytically described. Explicit dependencies on range, distance to the boundary, and physical parameters of contacting media are obtained. These results are of applied value for modern ultrasonic cleaning techniques because they allow one to describe
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Study of Resonant Peak Characteristics of Flow-Induced Noise in Small-Aperture Cavity J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2022-12-31 Zhenan Song, Daoqing Chang, Hongling Sun
The influences of the length and width of small-aperture cavity are calculated with the k–𝜀 model and large eddy simulation on the frequencies of resonant peaks of flow-induced cavity noise at different flow velocities in water. The calculated results show that the semi-empirical Rossiter formulas are only suitable for large-aperture models. For small-aperture cavity models, the resonance peak frequencies
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Sound transmission loss of meta-acoustic barriers with anomalous effective-mass J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2022-12-29 Muhammad Ali Bablu, Oluwafemi P. Akinmolayan, James M. Manimala
Meta-acoustic barriers (MABs) that are inspired by acoustic metamaterials (AM) offer opportunities to defy mass law-driven sound transmission loss (TL) performance that is characteristic of conventional acoustic barriers. In this analytical parametric study, the TL behavior of MABs that incorporate various local oscillator configurations are analyzed using an effective-mass modeling approach. Resonant
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Coupled Analysis of Acoustic Space and Thin-Plate Vibrations by a Lumped-Mass Model Using Raviart–Thomas Elements J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2022-11-16 Shotaro Hisano, Satoshi Ishikawa, Hiroyuki Iwamoto
Suppression of noise and vibration in machine products is an important problem, and many methods have been studied. In particular, structural–acoustic coupled effects due to the weight reduction of machines cannot be ignored. In structural–acoustic coupled analysis, the finite-element method in which the acoustic space is described by sound pressure and the structure is described by displacement is
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History of the Journal of Theoretical and Computational Acoustics J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2022-09-30 Allan D. Pierce
A brief history is given for the journal currently titled Journal of Theoretical and Computational Acoustics.
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Selected Topics of the Past Thirty Years in Ocean Acoustics J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2022-09-30 Michael D. Collins, Altan Turgut, Michael J. Buckingham, Peter Gerstoft, Martin Siderius
This paper reviews some of the highlights of selected topics in ocean acoustics during the thirty years that have passed since the founding of the Journal of Theoretical and Computational Acoustics. Advances in computational methods and computers helped to make computational ocean acoustics a vibrant area of research during that period. The parabolic equation method provides an unrivaled combination
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Recent Advances in Acoustic Boundary Element Methods J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2022-09-30 Simone Preuss, Caglar Gurbuz, Christopher Jelich, Suhaib Koji Baydoun, Steffen Marburg
The modern scope of boundary element methods (BEM) for acoustics is reviewed in this paper. Over the last decades the BEM has gained popularity despite suffering from shortcomings, such as fictitious eigenfrequencies and poor scalability due to its dense and frequency-dependent coefficient matrices. Recent research activities have been focused on alleviating these drawbacks to enhance BEM usability
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Experimental Validations of Reconstructed Excitation Forces Acting Inside a Solid Enclosure. Part I: Exterior Region J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2022-09-30 Yazhong Lu, Lingguang Chen, Pan Zhou, Sean F. Wu
This paper presents the experimental validations of reconstructing the characteristics of the excitation forces that act inside a vibrating structure, which includes the location, type, amplitude, and spectrum, based on a single set of measurements of the normal surface velocity on the exterior surface by using the modified Helmholtz Equation Least Squares (HELS) method, as if one could see through
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Experimental Validations of Reconstructed Excitation Forces Acting Inside a Solid Enclosure. Part II: Interior Region J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2022-09-30 Yazhong Lu, Lingguang Chen, Pan Zhou, Sean F. Wu
Part II of this paper discusses experimental validations of the reconstructed excitation forces acting inside a vibrating structure with the fluid-loading effect taken into consideration. Specifically, the characteristics of the excitation forces such as their locations, types, amplitudes, and spectra are reconstructed by using the modified Helmholtz Equation Least Squares (HELS) method, based on a
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Sound Radiation of a Line Source with General Time Dependence Moving Above an Interface Between Two Homogeneous Semi-Infinite Fluid Media J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2022-09-30 Rafael Piscoya, Martin Ochmann
In this paper, the sound field due to a line source moving above a homogeneous semi-infinite fluid medium emitting an arbitrary time signal is deduced. The source moves with a constant velocity parallel to the flat interface at a fixed height. The expression for the velocity potential is obtained from the impulse response of the stationary line source by including the motion of the source in the source
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Comparison of the FWI-Adjoint and Time Reversal Methods for the Identification of Elastic Scatterers J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2022-09-30 Daniel Rabinovich, Eyal Amitt, Dan Givoli, Eli Turkel
The paper falls into the category of computational methods for inverse scattering techniques for the identification of scatterers. We consider a linear elastodynamic problem and compare two popular methods for identifying a scatterer in the domain. Finite elements are employed with each of the two methods for spatial discretization. One method considered is Full Waveform Inversion using a gradient-based
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Broadband Acoustic Metamaterial Design via Machine Learning J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2022-09-30 Thang Tran, Feruza A. Amirkulova, Ehsan Khatami
Acoustic metamaterials are engineered microstructures with special mechanical and acoustic properties enabling exotic effects such as wave steering, focusing and cloaking. In this research, we develop a new machine learning framework for predicting optimal metastructures such as planar configurations of scatterers with specific functionalities. Specifically, we implement this framework by combining
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Solving Thin-Body Acoustic Problems Over an Impedance Plane with a Fast Multipole Indirect Boundary Element Method J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2022-09-30 Meng-Hui Liang, Yong-Bin Zhang, Chang-Jun Zheng, Shuai Wang, Chuan-Xing Bi
This paper presents a fast multipole indirect boundary element solver for the thin-body acoustic problems over an infinite impedance plane. The half-space impedance Green’s function involving a complex line source to approximate the porous ground effects is employed in the indirect boundary integral equation (IBIE), which makes that both mass-like and spring-like impedance conditions on the infinite
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Optimization of Acoustic Channels to Minimize Scattered Pressure Fields J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2022-09-30 Benjamin C. Treweek, Clay M. Sanders, Wilkins Aquino, Timothy F. Walsh
Acoustic and elastic metamaterials have shown potential for many different applications in wave manipulation and structural isolation. Minimization of a scattered wave field has been identified as an important use for such materials, and a wide variety of designs have been proposed for this purpose. Several of these designs face practical challenges (e.g. pentamode designs, which are difficult to manufacture)
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The Striation-Correlation-Based Beamforming for Estimating the Green’s Function in a Shallow Water Waveguide J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2022-09-30 Chang Peng Liu, Shi Hong Zhou, Yu Bo Qi, Xue Dong Zhang, Di Zhang, Xi Shan Yang
In shallow water, there exist regular interference striations on the structured sound intensity pattern versus frequency and element location of a horizontal array. Beamforming along the striation with frequency-shifted pressure can improve the correlation among array signals, but the beam focusing performance is limited by the source spectrum (e.g. random phase spectrum generated from ship-radiated
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A Science Scandal that Culminated in Declaring the Ivory-billed Woodpecker (Campephilus principalis) Extinct J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2022-06-30 Michael D. Collins
The Ivory-billed Woodpecker (Campephilus principalis) is an ultra-elusive bird that has repeatedly been feared extinct only to be rediscovered during the past hundred years. An article that was featured on the cover of Science in 2005 announced the most recent rediscovery in Arkansas, which was the first report of this species by ornithologists in several decades. Another group of ornithologists reported
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Determination of Modes in the Ice–Water Bi-layer Waveguide J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2022-06-22 Shengyu Tang, Guangping Zhu, Xiaoyu Wang, Jingwei Yin
The seismic method on ice provides rich information and a feasible technical way for acoustic study in ice-covered water. This paper presents a method to determine the modes in ice–water bi-layer waveguides. We achieve the purpose by deducing the scaled boundary formulation for solid and fluid layers then coupling them with the coupling matrix. The wave numbers and mode shapes are compared with the
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Modeling Sound Absorption of Graded Foam Absorbers via Polynomial Surrogate Technique J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2022-06-22 Van Hai Trinh, Dengke Li, Mu He, Xin Li
Transports and sound absorption performance of foam-based absorbers are influenced by the morphologies of their pore connections. Understanding the microstructure–property relationships of sound absorbers can provide valuable insights and guidance for designing and manufacturing steps. We develop in this paper surrogate models based on the polynomial chaos expansion to predict the acoustic behavior
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Efficient Mode-Coupling Calculation for Constant Depth Ocean with Range-Dependent Sound–Speed Fluctuation J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2022-06-17 Jungyong Park, Haesang Yang
In this paper, a criterion for efficient coupled-mode matrix calculation in a constant depth ocean with range-dependent sound–speed fluctuation is proposed. The usual stepwise coupled mode requires high computational power to calculate the mode-coupling matrix at each interface of the range segment. To reduce the computational complexity, the criterion for selecting appropriate mode pairs, which strongly
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Analyzing motorcycle low-frequency noise J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2022-06-17 Yazhong Lu, Lingguang Chen, Sean F. Wu, Jingyan Hu, Huijun Li
This paper presents analyses of the 3D acoustic fields generated by motorcycles at very low frequencies ( < 150 Hz) at the idle speed and during sudden acceleration. Diagnosis and analyses of sound sources at low frequencies have always been a significant challenge because the directivity of low-frequency sound is very poor. To date, there are no research papers and/or reports that have demonstrated
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Saddle Point Method for Transient Processes in Waveguides J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2022-03-22 Andrey V. Shanin, Andrey I. Korolkov, Kseniia S. Kniazeva
A modification of the saddle point method is proposed for computation of nonstationary wave processes (pulses) in waveguides. The dispersion diagram of the waveguide is continued analytically. A set of possible saddle points on the dispersion diagram is introduced. A method of checking whether the particular saddle points contribute terms to the field decomposition is proposed. A classification of
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Localizing Submerged Acoustic Sources Under Adverse Conditions J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2022-03-21 Michael D. Collins, Laurie T. Fialkowski, Joseph F. Lingevitch
This paper reviews various approaches for localizing submerged acoustic sources under adverse conditions. It is essential to obtain data of the highest possible quality when there are adverse conditions, such as uncertainties in the environment, source motion, and low signal-to-noise ratio. Focalization is an approach in which the source location and environmental parameters are treated as unknowns
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Determining excitation forces acting on the interior surface of an enclosure. Part I: Theory J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2022-03-21 Sean F. Wu, Pan Zhou, Yazhong Lu
Part I of this paper presents analytic solutions for reconstructing the excitation forces that act on the interior surfaces of a finite solid rectangular enclosure with the fluid loading effect taken into consideration, given vibroacoustic data in the exterior region. The reason for selecting a simple structure is to facilitate the reconstruction of excitation forces. To validate these analytic solutions
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Determining excitation forces acting on the interior surface of an enclosure. Part II: Numerical simulations J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2022-03-21 Pan Zhou, Sean F. Wu, Yazhong Lu
Part II of this study presents numerical simulations of reconstructing the excitation forces acting on the interior surface of an enclosure, based on the vibroacoustic information collected in the exterior region. Various types of excitation forces such as distributed, line, and point forces are considered. Moreover, fluid loading inside the enclosure is considered in the numerical simulations. Analytical
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Rationale for Publishing Open Access J. Theor. Comput. Acoust. (IF 1.9) Pub Date : 2022-03-18 Allan D. Pierce
Authors submitting scientific articles to journals now have the option of publishing their articles open access. This entails paying the publisher a fee that will insure that readers can download a pdf of the article without charge from an internet site. This option is of relatively recent vintage and has become recently somewhat popular among authors who desire their articles to be widely read. The