Inversion of a cylindrical vibrating body in shallow water from aspect-limited data using filtered SVD and the L-curve
Abstract:The distribution of the normal velocity of a cylindrical vibrating body in a shallow water waveguide is retrieved from nearfield pressures sampled by a vertical array of hydrophones placed on one side of the body only and which partially covers the water column between the bottom (fluid penetrable) and the air surface (pressure-release). A contour integral formulation of the wavefield whose Nyström method yields the discrete counterpart is used, the Green's function of the layered environment being calculated by fast Fourier transforms for nonequispaced data. The ill-posed linear inversion is performed by filtered Singular Value Decomposition, an optimum Tikhonov's regularization parameter being determined by the L-curve. Circular and elliptic contours and several types of vibration are simulated at a low and a high frequency. Regularization is needed for small sampling steps or large data errors. The inversion method appears robust against measurement noise and uncertainty on each hydrophone location, with a generally good though often underestimated regularization parameter. In addition, strong transmission in the bottom and a short receiver array (down to one-fifth of the water column) are factors which do not degrade the results significantly with respect to those obtained with a hard bottom and an array spanning half or more of the column.
Document Type: Research Article
Publication date: September 1, 1996
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- Acta Acustica united with Acustica, published together with the European Acoustics Association (EAA), is an international, peer-reviewed journal on acoustics. It publishes original articles on all subjects in the field of acoustics, such as general linear acoustics, nonlinear acoustics, macrosonics, flow acoustics, atmospheric sound, underwater sound, ultrasonics, physical acoustics, structural acoustics, noise control, active control, environmental noise, building acoustics, room acoustics, acoustic materials, acoustic signal processing, computational and numerical acoustics, hearing, audiology and psychoacoustics, speech, musical acoustics, electroacoustics, auditory quality of systems. It reports on original scientific research in acoustics and on engineering applications. The journal considers scientific papers, technical and applied papers, book reviews, short communications, doctoral thesis abstracts, etc. In irregular intervals also special issues and review articles are published.
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