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Inverse Scattering Problems for the Objects Buried in Penetrable Cylinders

出版	2009
URL	http://books.google.com.hk/books?id=lO3WnQEACAAJ&hl=&source=gbs_api

註釋This study is devoted to propose numerical solutions of new and significant types of inverse scattering problems in a resonance region where the diameters of the scatterers and the operating wavelength are of comparable size. In order to provide a good consistency with some practical applications arbitrarily shaped obstacles buried in arbitrarily shaped penetrable cylinders are illuminated by a single time-harmonic electromagnetic plane wave at a fixed frequency. We assume the Dirichlet or impedance boundary condition for the buried obstacle and transmission or the conductive boundary conditions for the penetrable cylinder according to the problem under investigation. Direct scattering problems are solved to obtain the scattered near/far-field for using as a synthetic data in the solutions of the inverse problems whose aims are to determine the impedance function, the location and the shape, the shape and the conductivity function. For the solutions of the direct and inverse scattering problems a boundary integral equation method is employed depending on different potential approaches. A new algorithm is presented to find the total fields in the interior and the exterior domains of the penetrable cylinders from the knowledge of the scattered field. The integral equations are solved by using Nyström and collocation methods. Moreover, in order to obtain stable solutions of the first kind of Fredholm-type integral equations Tikhonov regularization is applied. The applicability and the effectiveness of the proposed inversion methods are validated also with noisy data and satisfactory numerical results are obtained as illustrated in the thesis.