scholarly journals Optimization of the Equivalent Source Configuration for the Equivalent Source Method

2021 ◽  
Vol 9 (8) ◽  
pp. 807
Author(s):  
Lanyue Zhang ◽  
Jia Wang ◽  
Desen Yang ◽  
Bo Hu ◽  
Di Wu
Keyword(s):  
Acoustic Radiation ◽  
Optimal Solution ◽  
Sound Field ◽  
Optimization Method ◽  
Field Calculation ◽  
Equivalent Source ◽  
Source Method ◽  
Calculation Results ◽  
Equivalent Sources ◽  
Equivalent Source Method

The equivalent source method is widely applied to study structural acoustic radiation in an underwater environment. However, there is still uncertainty in arranging the equivalent source, and the current mainstream configuration method needs a large number of equivalent sources, limiting its practical applicability. In this paper, an equivalent source configuration method that is simple, effective, and easy to implement, and which based on a tradeoff between the ill condition of the transfer matrix and the adequacy of the simulated structure’s radiated sound field, is proposed. The optimization method can derive the appropriate positions and quantity of monopole equivalent sources simultaneously. The method does not yield an optimal solution in a strict mathematical sense but provides satisfactory results compared with those obtained by uniformly distributed equivalent sources. Numerical simulation results showed that the optimization method derives accurate sound field calculation results with a relatively small number of equivalent sources, significantly reducing the number of subsequent calculations needed. Finally, the experiments conducted with a cylindrical shell structure verified the validity and practicality of the proposed method.

Reconstruction of semi-free transient sound field under different reflection conditions using an extended interpolated time-domain equivalent source method

2014 ◽  
Vol 229 (5) ◽  
pp. 895-905 ◽  
Author(s):  
Siwei Pan ◽  
Weikang Jiang ◽  
Shang Xiang
Keyword(s):  
Time Domain ◽  
Free Field ◽  
Sound Field ◽  
Sound Sources ◽  
Equivalent Source ◽  
Source Method ◽  
Equivalent Sources ◽  
The Time Domain ◽  
Reflecting Surface ◽  
Equivalent Source Method

Transient acoustic field can be rebuilt directly in the time-domain via the interpolated time-domain equivalent source method (ITDESM). However, this method requires that the reconstruction should be addressed in the free-field only, which can hardly be met in the engineering noise problems. To circumvent this difficulty, an extended ITDESM procedure is developed by extending the ITDESM from the free-field to the semi-free-field. In this approach, the time-domain equivalent sources are placed not only near the actual sound sources but also around their image sources with respect to the planar reflecting surface. The solving procedure of the equivalent source strengths is improved to decrease the computing load. The reflection conditions treated here can be arbitrary, i.e. both perfectly rigid and impedance-effected. Reconstruction results of the transient sound field radiated from three monopoles under different reflection conditions demonstrate the validity and applicability of the proposed method.

scholarly journals Optimization of Equivalent Source Configuration for an Independent-Equivalent Source Method in Half-Space Sound Field

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Wen-Qian Jing ◽  
Huawei Wu ◽  
Jin-Quan Nie
Keyword(s):  
Numerical Simulations ◽  
Half Space ◽  
Sound Field ◽  
Reconstruction Accuracy ◽  
Equivalent Source ◽  
Source Method ◽  
Equivalent Sources ◽  
Optimal Configurations ◽  
Measured Pressure ◽  
Equivalent Source Method

In the situation that vibrating objects are located above a reflecting plane, an independent-equivalent source method (I-ESM) regards the reflections due to the plane as being radiated by equivalent sources placed under the plane and then the half-space sound field is reconstructed by matching the measured pressure with the equivalent sources distributed within the vibrating object and those substituting for reflections. But, this method heavily depends on the equivalent source configuration and may obtain bad reconstruction results if the equivalent sources are arranged incorrectly. This paper deals with the optimization of the equivalent source configuration to ensure I-ESM always perform well. Through numerical simulations and experiments, the influence of equivalent source configurations on the reconstruction accuracy was studied and optimal configurations were acquired and confirmed.

Sound Field Prediction and Separation in a Moving Medium Using the Time-Domain Equivalent Source Method

2017 ◽  
Vol 103 (3) ◽  
pp. 401-410 ◽  
Author(s):  
Zhao-Huan Wang ◽  
Chuan-Xing Bi ◽  
Xiao-Zheng Zhang ◽  
Yong-Bin Zhang
Keyword(s):  
Time Domain ◽  
Sound Field ◽  
Moving Medium ◽  
Equivalent Source ◽  
Source Method ◽  
The Time Domain ◽  
Equivalent Source Method

scholarly journals A Compressed Equivalent Source Method Based on Equivalent Redundant Dictionary for Sound Field Reconstruction

2019 ◽  
Vol 9 (4) ◽  
pp. 808 ◽  
Author(s):  
Yansong He ◽  
Liangsong Chen ◽  
Zhongming Xu ◽  
Zhifei Zhang
Keyword(s):  
Dynamic Range ◽  
Sound Field ◽  
High Dynamic Range ◽  
Redundant Dictionary ◽  
Equivalent Source ◽  
Practical Applications ◽  
Field Reconstruction ◽  
Source Method ◽  
Value Decomposition ◽  
Equivalent Source Method

The equivalent source method (ESM) based on compressive sensing (CS) requires that the source has a sparse or approximately sparse representation in a suitable basis or dictionary. However, in practical applications, it is not easy to find the appropriate basis or dictionary due to the indeterminate characteristics of the source. To solve this problem, an equivalent redundant dictionary is constructed, which contains two core parts: one is the equivalent dictionary used in the CS-based ESMs under the sparse assumption, and the other one is the orthogonal basis obtained by the singular value decomposition (SVD). On this foundation, a method named compressed ESM based on the equivalent redundant dictionary (ERDCESM) is proposed to enhance the performances of source field reconstruction for different types of sources. Moreover, inspired by the idea of functional beamforming (FB), ERDCESM with order v (ERDCESM- v ) can possess a high dynamic range when detecting the source location. The numerical simulations are carried out at different frequencies to evaluate the performance of the proposed method, and the results suggest that the proposed method performs well both for sparse and even spatially extended sources. The validity and practicality of the proposed method are also verified by the experimental results.

A scattered equivalent‐source method for interpolation and gridding of potential‐field data in three dimensions

Geophysics ◽  
1992 ◽  
Vol 57 (4) ◽  
pp. 629-636 ◽  
Author(s):  
Lindrith Cordell
Keyword(s):  
Observation Point ◽  
Three Dimensions ◽  
Level Surface ◽  
Equivalent Source ◽  
Source Method ◽  
Data Points ◽  
Data Error ◽  
Equivalent Sources ◽  
Minimum Curvature ◽  
Equivalent Source Method

Potential‐field geophysical data observed at scattered discrete points in three dimensions can be interpolated (gridded, for example, onto a level surface) by relating the point data to a continuous function of equivalent discrete point sources. The function used here is the inverse‐distance Newtonian potential. The sources, located beneath some of the data points at a depth proportional to distance to the nearest neighboring data point, are determined iteratively. Areas of no data are filled by minimum curvature. For two‐dimensional (2-D) data (all data points at the same elevation), grids calculated by minimum curvature and by equivalent sources are similar, but the equivalent‐source method can be tuned to reduce aliasing. Gravity data in an area of high topographic relief in southwest U.S.A. were gridded by minimum curvature (a 2-D algorithm) and also by equivalent sources (3-D). The minimum‐curvature grid shows strong correlation with topography, as expected, because variation in gravity effect due to variation in observation‐point elevation (topography) is ignored. However, the data gridded and reduced to a level surface at the mean observation‐point elevation, by means of the equivalent‐source method, also show strong correlation with topography even though variation in observation‐point elevation is accounted for. This can be attributed mostly to the inadequacy of constant‐density terrain correction or to data error. Three‐dimensional treatment in this example is required as a means of calculating the data onto a level surface, above regions where data and geologic sources overlap, as a necessary first step for making geologic correction, variable‐density terrain correction, and evaluating data error. Better spectral estimates are obtained by direct calculation of the Fourier transform of the equivalent‐source function than by the discrete fast Fourier transform computer algorithm.

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