When solving acoustic radiation problem in the routine boundary point method (BPM), the inverse of the particular solution matrix of surface normal velocities is needed and the matrix must be full rank and reversible....When solving acoustic radiation problem in the routine boundary point method (BPM), the inverse of the particular solution matrix of surface normal velocities is needed and the matrix must be full rank and reversible. However, the type of the particular solution sources is single and the sources are not linear independent, so the locations of the particular solution sources inside the vibrating body must be selected carefully. But, in the routine BPM, the loca-tions are determined by an experiential formula, so the method may be invalid for a complicated vibrating body. In this paper, the construction method of the particular solution sources is improved first, and the singular value decomposi-tion (SVD) technique and the Moore-Penrose pseudoinverse are adopted to realize the inversion. As a consequence, the particular solution matrix of surface normal velocities can be non-full rank and the locations of the particular sources can be determined easily. On the basis of the improved BPM, the spherical wave sources of different orders are proposed to be the particular solution sources. Here, all particular solution sources are located on only one point inside the vibrating body, so the problem of the locations of the particular solu-tion sources is thoroughly solved, and such particular solu-tion sources that are useless for the calculation results are discarded. The theoretical model is established at first, and then the proposed method is used to realize the nearfield acoustic holography (NAH). Subsequently, an experiment is investigated to validate the feasibility and correctness of the proposed method and its application to acoustic holography.展开更多
In the light of the concept of spherical wave source, the theoretical model of nearfield acoustic holography (NAH) based on the spherical wave superposition method (SWSM), including reconstruction of expansion coeffic...In the light of the concept of spherical wave source, the theoretical model of nearfield acoustic holography (NAH) based on the spherical wave superposition method (SWSM), including reconstruction of expansion coefficients, prediction of acoustic field, error sensitivity analysis, regularization method and a searching method with dual measurement surfaces for determining the optimal number of expansion terms, is established. Subsequently, the spherical wave source boundary point method (SWSBPM) and its application in the NAH are introduced briefly. Considering the similarity of the SWSM and the SWSBPM for realizing the NAH, they are compared. The similarities and differences of the two methods are illuminated by a rigorous mathematical justification and two experiments on a single source and two coherent sources in the semi-free acoustic field. And, the superiority of the NAH based on the SWSBPM is demonstrated.展开更多
A multi-channel acoustic holographic measurement and analysis system has been developed and been applied to validate sound field separation technique with double holographic planes. Moreover, some methods to enhance s...A multi-channel acoustic holographic measurement and analysis system has been developed and been applied to validate sound field separation technique with double holographic planes. Moreover, some methods to enhance separation precision have also been given, based on the error analysis of the technique. The holographic pressures on double planes are measured and analyzed by the developed holographic system when some background sources exist. The experimental results show that the separation technique proposed can suppress the influence of the background sources on holographic reconstruction effectively, and the reconstructed sound field and source identification can be obtained correctly.展开更多
Sound field separation technique with double holographic planes is proposed, which overcomes the limitation on applications of near-field acoustic holography (NAH) and broadband acoustic holography from intensity meas...Sound field separation technique with double holographic planes is proposed, which overcomes the limitation on applications of near-field acoustic holography (NAH) and broadband acoustic holography from intensity measurement (BAHIM). The limitation is that sound field on one side of holographic plane must be free, that is to say, all the sound sources must be confined to the other side; but it is not easy to achieve for industrial measurements. The technique builds the sound field separation formula in wave number domain according to the wave field extrapolation theorem, and the sound pressure caused by sources on one side of holographic plane can be obtained as expected by taking two-dimensional Fourier transform of the formula. The derivation of the principle verifies the technique theoretically. The numerical simulations demonstrate its feasibility and effectiveness.展开更多
文摘When solving acoustic radiation problem in the routine boundary point method (BPM), the inverse of the particular solution matrix of surface normal velocities is needed and the matrix must be full rank and reversible. However, the type of the particular solution sources is single and the sources are not linear independent, so the locations of the particular solution sources inside the vibrating body must be selected carefully. But, in the routine BPM, the loca-tions are determined by an experiential formula, so the method may be invalid for a complicated vibrating body. In this paper, the construction method of the particular solution sources is improved first, and the singular value decomposi-tion (SVD) technique and the Moore-Penrose pseudoinverse are adopted to realize the inversion. As a consequence, the particular solution matrix of surface normal velocities can be non-full rank and the locations of the particular sources can be determined easily. On the basis of the improved BPM, the spherical wave sources of different orders are proposed to be the particular solution sources. Here, all particular solution sources are located on only one point inside the vibrating body, so the problem of the locations of the particular solu-tion sources is thoroughly solved, and such particular solu-tion sources that are useless for the calculation results are discarded. The theoretical model is established at first, and then the proposed method is used to realize the nearfield acoustic holography (NAH). Subsequently, an experiment is investigated to validate the feasibility and correctness of the proposed method and its application to acoustic holography.
基金supported by the National Natural Science Foundation of China(Grant No.50275044)the Research Fund for the Doctoral Program of Higher Education(Grant No 2OO2O359O05).
文摘In the light of the concept of spherical wave source, the theoretical model of nearfield acoustic holography (NAH) based on the spherical wave superposition method (SWSM), including reconstruction of expansion coefficients, prediction of acoustic field, error sensitivity analysis, regularization method and a searching method with dual measurement surfaces for determining the optimal number of expansion terms, is established. Subsequently, the spherical wave source boundary point method (SWSBPM) and its application in the NAH are introduced briefly. Considering the similarity of the SWSM and the SWSBPM for realizing the NAH, they are compared. The similarities and differences of the two methods are illuminated by a rigorous mathematical justification and two experiments on a single source and two coherent sources in the semi-free acoustic field. And, the superiority of the NAH based on the SWSBPM is demonstrated.
文摘A multi-channel acoustic holographic measurement and analysis system has been developed and been applied to validate sound field separation technique with double holographic planes. Moreover, some methods to enhance separation precision have also been given, based on the error analysis of the technique. The holographic pressures on double planes are measured and analyzed by the developed holographic system when some background sources exist. The experimental results show that the separation technique proposed can suppress the influence of the background sources on holographic reconstruction effectively, and the reconstructed sound field and source identification can be obtained correctly.
文摘Sound field separation technique with double holographic planes is proposed, which overcomes the limitation on applications of near-field acoustic holography (NAH) and broadband acoustic holography from intensity measurement (BAHIM). The limitation is that sound field on one side of holographic plane must be free, that is to say, all the sound sources must be confined to the other side; but it is not easy to achieve for industrial measurements. The technique builds the sound field separation formula in wave number domain according to the wave field extrapolation theorem, and the sound pressure caused by sources on one side of holographic plane can be obtained as expected by taking two-dimensional Fourier transform of the formula. The derivation of the principle verifies the technique theoretically. The numerical simulations demonstrate its feasibility and effectiveness.
