Comments on the article “Applications of Directional Wavefield Decomposition,Phase Space,and Path Integral Methods to Seismic Wave Propagation and Inversion” [Pure Appl. Geophys. 159 (2002) 1637–1679]     

P. M.?JordanEmail author  M. F.?Werby 《Pure and Applied Geophysics》2004,161(8):1807-1813

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Beam forming on bottom-interacting tow-ship noise     

Kuperman  W. Werby  M. Gilbert  K. Tango  G. 《Oceanic Engineering, IEEE Journal of》1985,10(3):290-298

Ship noise received on a horizontal array towed behind the ship is shown to be useful as a potentially diagnostic tool for estimating local acoustic bottom properties. In numerical simulations, tow-ship noise which bounces off the bottom is processed on a beamformer that shows the arrival angles; the beamformer output is readily interpreted by relating it to the Green's function of the acoustic wave equation. Simple signal processing is shown to be sufficient to extract the propagation angles of the "trapped" (i.e., propagating) modes of the acoustic waveguide. By relating the trapped modes to a basic geophysical model of the bottom, one can predict acoustic-propagation conditions for a particular bottom-interacting ocean acoustic environment.  相似文献   

Broadside resonance scattering from elastic spheroids     

Werby  M.F. Gaunaurd  G.C. 《Oceanic Engineering, IEEE Journal of》1989,14(4):400-406

The authors study the scattering of monochromatic plane acoustic waves incident at 90° angles relative to the axis of symmetry (i.e. broadside or beam aspect) on solid elastic spheroids. In this analysis, the aspect ratios of the spheroids vary in the range 2⩽L/ D⩽5 in steps of one. The nondimensional frequency kL /2 is kept within the band 2⩽kL/2⩽24. A numerical solution based on a modification of the T-matrix method is generated. The authors generate predictions for the backscattered echoes and graphically display their frequency dependence in order to study the resonance features present within them. In this three-dimensional study, the authors identify the (leaky) Rayleigh-type resonances consistent with those present in infinite cylinders  相似文献   

Scattering from objects submerged in unbounded and bounded oceans     

Werby  M. Evans  R. 《Oceanic Engineering, IEEE Journal of》1987,12(2):380-394

We present a study of scattering from objects in a free unbounded ocean and for objects near an interface and in a waveguide. Major emphasis is on results and discussion of theoretical development is limited to the essentials. An examination of backscattered echoes is presented for elastic targets. Angular distributions are examined for all target types, as well as environments, with the exception of objects in a waveguide. In a waveguide, beamforming techniques are most appropriate for detection of objects. We also examine rigid, soft, and elastic objects that are either spheroidal or cylindrical. Aspect ratios studied range from 3:1 to 24:1, andkL/2ranges (kis wavenumber andLis the length of the object) are from 3 to 120.  相似文献