Journal ArticleDOI
Generalized dual space indicator method for underwater imaging
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TLDR
In this paper, a generalized dual space indicator method for imaging an unknown obstacle in ocean environments is presented, based on the observation that the combination (weighted integration) of the measured scattered field can approximate the Green function very well when the source point is inside the obstacle, but not so well if the source is outside the obstacle.Abstract:
This paper presents a generalized dual space indicator method for imaging an obstacle in ocean environments. The method is based on the observation that the combination (weighted integration) of the measured scattered field can approximate the Green function very well when the Green function's source point is inside the obstacle, but not so well when the source is outside the obstacle. We set up an integral equation whose right-hand side is the Green function with a source point from a searching region. From our numerical experiments, we notice that the norm of the solution of the integral equation has local extrema that lie inside the unknown obstacle. Plotting the norm as a function of the source point in the searching region, and filtering out the region with no local extrema of the norm, we obtain a good image of the unknown obstacle. Imaging algorithms and numerical examples are presented.read more
Citations
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The linear sampling method in a waveguide: A modal formulation
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TL;DR: In this article, the linear sampling method used to retrieve obstacles in a 2D or 3D acoustic waveguide has been studied, and it is shown that the numerical reconstruction of obstacles by using the far field is feasible, even by using a few incident waves.
Journal ArticleDOI
On the Mathematical Basis of the Linear Sampling Method
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TL;DR: In this paper, the authors give a mathematical justification of the linear sampling method for arbitrary z by using the theory of integral equations of first kind with singular kernels, and show that a linear integral equation has a solution that becomes unbounded as a parameter z approaches the boundary of the scatterer D from inside D. However, except for the transmission problem, the case where z is in the exterior of D is unresolved.
References
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Inverse Acoustic and Electromagnetic Scattering Theory
David Colton,Rainer Kress +1 more
TL;DR: Inverse Medium Problem (IMP) as discussed by the authors is a generalization of the Helmholtz Equation for direct acoustical obstacle scattering in an Inhomogeneous Medium (IMM).
Book ChapterDOI
A simple method for solving inverse scattering problems in the resonance region
TL;DR: In this paper, an inversion scheme for two-dimensional inverse scattering problems in the resonance region is proposed, which does not use nonlinear optimization methods and is relatively independent of the geometry and physical properties of the scatterer, assuming that the far field pattern corresponding to observation angle and plane waves incident at angle is known for all.
Journal ArticleDOI
Use of calculated sound fields and matched‐field detection to locate sound sources in shallow water
TL;DR: In this article, the detection factor DF = ΣJj=1 cjc*k (c0jc0k*) * ǫ * * � is proposed as a reasonable measure for determination of whether a set of sound pressure measurements is a good fit to calculated values of {cj} for an assumed location of the sound source.
Journal ArticleDOI
Multiple scattering analysis for a target in an oceanic waveguide
TL;DR: In this paper, a multiple-scattering approach is developed for the acoustic scattering from a target in a range-independent oceanic waveguide, which is explicitly summed and a solution is obtained in closed form.
Journal ArticleDOI
A boundary integral equation method for acoustic scattering in a waveguide with nonplanar surfaces
Trevor W. Dawson,John A. Fawcett +1 more
TL;DR: In this paper, a boundary integral equation method (BIEM) is formulated to compute the scattering of underwater sound from compact deformations of an oceanic waveguide's surfaces, which involves only integrations over the finite area of the waveguide surface deformations.