Acoustic Sensitivity Analysis Using the Distributed Source Energy Boundary Point Method

2011 ◽  
Vol 130-134 ◽  
pp. 76-79
Author(s):  
Li Tao Chen ◽  
Jian Chen ◽  
Bing Rong Zhang ◽  
Wu Zhang
Keyword(s):  
Boundary Point ◽  
Low Noise ◽  
Point Method ◽  
Design Parameters ◽  
Distributed Source ◽  
Boundary Point Method ◽  
Acoustic Sensitivity ◽  
Low Noise Design ◽  
Acoustical Energy

The determination of the sensitivity of the acoustical characteristics of vibrating systems with respect to the variation of the design parameters can provide a method to low-noise design of mechanical structure objectively and quantitatively. Using the Distributed source energy boundary point method, the expressions of the change of the acoustical energy density with respect to design variable is presented in this paper. The Distributed source energy boundary point method is a speedy and precise method which can avoid the complex computing of the singularity integral in EBEM. The correctness and availability is validated by the numerical simulation.

Reconstruction and Separation in a Semi-Free Field by Using the Distributed Source Boundary Point Method-Based Nearfield Acoustic Holography

2007 ◽  
Vol 129 (3) ◽  
pp. 323-329 ◽  
Author(s):  
C. X. Bi ◽  
X. Z. Chen ◽  
R. Zhou ◽  
J. Chen
Keyword(s):  
Acoustic Field ◽  
Boundary Point ◽  
Free Field ◽  
Treatment Method ◽  
Point Method ◽  
Acoustic Source ◽  
Acoustic Holography ◽  
Distributed Source ◽  
Boundary Point Method ◽  
Nearfield Acoustic Holography

In a semi-free field, the acoustic field is composed of two components: the direct sound and the reflected sound. Because it is difficult to separate the direct sound from the acoustic field, conventional nearfield acoustic holography (NAH) methods cannot reconstruct an acoustic source and predict the acoustic field directly. Through utilization of the distributed source boundary point method (DSBPM)-based NAH, a treatment method for a semi-free field is proposed. In the method, the source in a semi-free field can be reconstructed correctly, and the acoustic field can be predicted and separated. An experiment on a speaker in a semi-anechoic chamber is carried out to verify the proposed method. By comparing the reconstructed and predicted results in DSBPM-based NAH with and without the proposed method, the proposed method is validated. The disadvantages of NAH without any treatment method in a semi-free field are demonstrated.

DISTRIBUTED SOURCE BOUNDARY POINT METHOD-BASED NEARFIELD ACOUSTIC HOLOGRAPHY FOR RECONSTRUCTING THE ACOUSTIC RADIATION FROM ARBITRARILY SHAPED OBJECTS

2006 ◽  
Vol 14 (04) ◽  
pp. 379-395
Author(s):  
C. X. BI ◽  
X. Z. CHEN ◽  
J. CHEN
Keyword(s):  
Boundary Point ◽  
Measurement Errors ◽  
Regularization Parameter ◽  
Point Method ◽  
Tikhonov Regularization Method ◽  
Acoustic Holography ◽  
Reconstruction Procedure ◽  
Distributed Source ◽  
Boundary Point Method ◽  
Nearfield Acoustic Holography

Nearfield acoustic holography (NAH) is an indirect technique for identifying noise sources and visualizing acoustic field. Recently, several different methods, such as the spatial Fourier transform method, the boundary element method (BEM) and the Helmholtz equation-least squares (HELS) method, have been used to realize the NAH successfully. In the paper, a novel numerical method, the distributed source boundary point method (DSBPM), is proposed to realize the NAH. In the method, the transfer matrices from the reconstructed surface to the hologram surface are constructed indirectly by a set of particular solution sources located inside the vibrating structure, and their inverses are carried out by singular value decomposition (SVD) technique. Additionally, considering the high sensitivity of the reconstructed solution to measurement errors, the Tikhonov regularization method is implemented to stabilize the reconstruction procedure and the regularization parameter is determined by L-curve criterion. Compared with the BEM-based NAH, the variable interpolation, the numerical quadrature, and the treatments of singular integral and nonuniqueness of solution are all avoided in the proposed method. Two numerical examples and an experiment are investigated to validate the feasibility and correctness of the proposed method.

scholarly journals A Modified Mann Iteration by Boundary Point Method for Finding Minimum-Norm Fixed Point of Nonexpansive Mappings

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Songnian He ◽  
Wenlong Zhu
Keyword(s):  
Fixed Point ◽  
Strong Convergence ◽  
Boundary Point ◽  
Real Hilbert Space ◽  
Nonexpansive Mappings ◽  
Iteration Process ◽  
Point Method ◽  
Minimum Norm ◽  
Mann Iteration ◽  
Boundary Point Method

LetHbe a real Hilbert space andC⊂H a closed convex subset. LetT:C→Cbe a nonexpansive mapping with the nonempty set of fixed pointsFix(T). Kim and Xu (2005) introduced a modified Mann iterationx0=x∈C,yn=αnxn+(1−αn)Txn,xn+1=βnu+(1−βn)yn, whereu∈Cis an arbitrary (but fixed) element, and{αn}and{βn}are two sequences in(0,1). In the case where0∈C, the minimum-norm fixed point ofTcan be obtained by takingu=0. But in the case where0∉C, this iteration process becomes invalid becausexnmay not belong toC. In order to overcome this weakness, we introduce a new modified Mann iteration by boundary point method (see Section 3 for details) for finding the minimum norm fixed point of Tand prove its strong convergence under some assumptions. Since our algorithm does not involve the computation of the metric projectionPC, which is often used so that the strong convergence is guaranteed, it is easy implementable. Our results improve and extend the results of Kim, Xu, and some others.

Orthogonal spherical wave source boundary point method and its application to acoustic holography

2004 ◽  
Vol 49 (16) ◽  
pp. 1758-1767 ◽  
Author(s):  
Chuanxing Bi ◽  
Xinzhao Chen ◽  
Jian Chen ◽  
Weibing Li
Keyword(s):  
Boundary Point ◽  
Spherical Wave ◽  
Point Method ◽  
Acoustic Holography ◽  
Wave Source ◽  
Boundary Point Method
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