Conical Statistical Optimal Near-Field Acoustic Holography with Combined Regularization

For the sound field reconstruction of large conical surfaces, current statistical optimal near-field acoustic holography (SONAH) methods have relatively poor applicability and low accuracy. To overcome this problem, conical SONAH based on cylindrical SONAH is proposed in this paper. Firstly, elementary cylindrical waves are transformed into those suitable for the radiated sound field of the conical surface through cylinder-cone coordinates transformation, which forms the matrix of characteristic elementary waves in the conical spatial domain. Secondly, the sound pressure is expressed as the superposition of those characteristic elementary waves, and the superposition coefficients are solved according to the principle of superposition of wave field. Finally, the reconstructed conical pressure is expressed as a linear superposition of the holographic conical pressure. Furthermore, to overcome ill-posed problems, a regularization method combining truncated singular value decomposition (TSVD) and Tikhonov regularization is proposed. Large singular values before the truncation point of TSVD are not processed and remaining small singular values representing high-frequency noise are modified by Tikhonov regularization. Numerical and experimental case studies are carried out to validate the effectiveness of the proposed conical SONAH and the combined regularization method, which can provide reliable evidence for noise monitoring and control of mechanical systems.

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Near Field Acoustic Holography for Cyclostationary Sound Field and its Partial Source Decomposition Procedure

Journal of Vibration and Acoustics ◽

10.1115/1.2110820 ◽

2005 ◽

Vol 127 (6) ◽

pp. 542-546 ◽

Cited By ~ 1

Author(s):

Quan Wan ◽

W. K. Jiang

Keyword(s):

Principal Component Analysis ◽

Sound Pressure ◽

Near Field ◽

Sound Field ◽

Principal Component ◽

Acoustic Holography ◽

Sound Sources ◽

Decomposition Procedure ◽

Spectrum Density ◽

Simulation Results

The cyclostationary near field acoustic holography (NAH) technique is proposed to overcome the limitations of the current NAH in analyzing cyclostationary sound field. The proposed technique adopts the cyclic spectrum density as the reconstructed physical quantity, instead of the spectrum of sound pressure. Moreover, introducing the principal component analysis into the technique, a partial source decomposition procedure is suggested to decompose the sound field radiated by multiple sound sources into some incoherent partial fields. More information about cyclostationary sound field can be shown clearly on the hologram of the proposed technique than NAH can, which is validated by the simulation results.

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Near-Field Acoustic Holography of Cyclostationary Sound Field

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.631-632.1318 ◽

2013 ◽

Vol 631-632 ◽

pp. 1318-1323

Author(s):

Min Peng

Keyword(s):

Time Series ◽

Sound Pressure ◽

Near Field ◽

Sound Field ◽

Rotating Machinery ◽

Stationary Field ◽

Acoustic Holography ◽

Complex Sound ◽

Radiated Sound ◽

Slice Method

The radiated sound field of rotating machinery or reciprocating machinery has a significant periodically time-variant nature. This is a kind of non-stationary sound field and called cyclostationary sound field. In the conventional planar near-field acoustic holography(PNAH), this kind of sound field is treated as stationary field, so the information relating to the change of frequency with time will be loss inevitably. In this article, the cyclic spectral density(CSD) instead of the complex sound pressure was adopted as reconstructing physical quantity in the PNAH, and the cyclostationary PNAH(CPNAH) technique was proposed. Meanwhile, focusing on the calculation complex of CSD and the accuracy of the cyclic nature extracted, the gathering slice method of CSD was proposed by referring time aliasing methods on time series. The experiment results illustrate that the cyclic nature of cyclostationary sound field may be extracted directly and the location of the source determined exactly as well.

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Development of Near-Field Acoustical Holograph and its Review

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.971-973.1598 ◽

2014 ◽

Vol 971-973 ◽

pp. 1598-1601

Author(s):

Xu Liu ◽

Xiao Qin Liu ◽

Chang Liu

Keyword(s):

Near Field ◽

Sound Field ◽

Separation Technique ◽

Acoustic Holography ◽

Noise Sources ◽

Engineering Applications ◽

Powerful Technique ◽

Experiment And Simulation ◽

Acoustical Holography ◽

Field Separation

Near-field acoustic holography (NAH) is a powerful technique for identifying noise sources and visualizing acoustic field.The theory and algorithm of NAH techniques are introduced , and it is proved by experiment and simulation. The researches on near field acoustical holography (NAH) are reviewed，including the sound field separation technique and Patch NAH technique arisen in recent years.The difficulties in NAH and research on current situations are discussed , Finally,some engineering applications are introduced by detailed examples.

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A gearbox fault diagnosis scheme based on near-field acoustic holography and spatial distribution features of sound field

Journal of Sound and Vibration ◽

10.1016/j.jsv.2012.12.018 ◽

2013 ◽

Vol 332 (10) ◽

pp. 2593-2610 ◽

Cited By ~ 24

Author(s):

Wenbo Lu ◽

Weikang Jiang ◽

Guoqing Yuan ◽

Li Yan

Keyword(s):

Spatial Distribution ◽

Fault Diagnosis ◽

Near Field ◽

Sound Field ◽

Acoustic Holography ◽

Distribution Features

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An Improved Tikhonov-Regularized Variable Projection Algorithm for Separable Nonlinear Least Squares

Axioms ◽

10.3390/axioms10030196 ◽

2021 ◽

Vol 10 (3) ◽

pp. 196

Author(s):

Hua Guo ◽

Guolin Liu ◽

Luyao Wang

Keyword(s):

Least Squares ◽

Tikhonov Regularization ◽

Regularization Method ◽

Nonlinear Least Squares ◽

Singular Values ◽

Exponential Model ◽

Singular Value ◽

Projection Algorithm ◽

Tikhonov Regularization Method ◽

Variable Projection

In this work, we investigate the ill-conditioned problem of a separable, nonlinear least squares model by using the variable projection method. Based on the truncated singular value decomposition method and the Tikhonov regularization method, we propose an improved Tikhonov regularization method, which neither discards small singular values, nor treats all singular value corrections. By fitting the Mackey–Glass time series in an exponential model, we compare the three regularization methods, and the numerically simulated results indicate that the improved regularization method is more effective at reducing the mean square error of the solution and increasing the accuracy of unknowns.

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Study of Spherical Near-Field Acoustic Holography with Rigid Spherical Microphone Array

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.546.156 ◽

2013 ◽

Vol 546 ◽

pp. 156-163

Author(s):

Xin Guo Qiu ◽

Ming Zong Li ◽

Huan Cai Lu ◽

Wei Jiang

Keyword(s):

Sound Source ◽

Microphone Array ◽

Near Field ◽

Sound Field ◽

Acoustic Holography ◽

Real Situation ◽

Helmholtz Equations ◽

Sound Sources ◽

Array Configuration ◽

Sphere Radius

The aim of this paper is to investigate the impacts of various parameters of rigid spherical microphone array in detecting and locating interior sound source. Helmholtz Equations are adopted to express the sound field produced by the incident field and scattered field. The gradient of the pressure is zero at the surface for the sphere is rigid. Both the incident and scattered coefficient could be obtained by solving the Helmholtz Equation using the boundary condition. Then the interior sound field could be detected and located on with the methodology of spherical near-field acoustic holography (SNAH). This study is developed in two aspects，one is configuring the microphone in various distribution in the same sphere radius, and the other one is changing the radius of sphere array. Numerical simulations are carried out to determine the optimum microphone array configuration and structure parameters. One, two, and three sound sources are arranged respectively in different displacement to the sphere center and in different angle direction to simulate the real situation. During the experiments, Omni-directional speakers and beeps are adopted as sound sources. The result shows that the method to detect and locate sound source in interior sound field is valid.

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Research on the Planar Near-Field Acoustic Holography for Cyclostationary Sound Field

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.105-107.164 ◽

2011 ◽

Vol 105-107 ◽

pp. 164-167

Author(s):

Zhi Min Chen ◽

Hai Chao Zhu ◽

Rong Fu Mao

Keyword(s):

Spectral Density ◽

Physical Quantity ◽

Sound Source ◽

Sound Pressure ◽

Near Field ◽

Sound Field ◽

Rotating Machines ◽

Carrier Wave ◽

Acoustic Holography ◽

Complex Sound

The conventional planar near-field acoustic holography is not suitable for cyclostationary sound field radiated by the rotating machines. When the cyclic spectral density (CSD), instead of the complex sound pressure, is adopted as reconstructed physical quantity, the modulating wave and carrier wave components of the cyclostationary sound field can be extracted exactly and so the cyclostationary planar near-field acoustic holography (CPNAH) technique was proposed. Simulation and experimental results show that the modulation characteristics of the cyclostationary sound field can be extracted effectively and the sound source can be localized accurately.

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