Quasi-analytical approximations and series in electromagnetic modelingстатья
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Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
Аннотация:The quasi-linear approximation for electromagnetic forward modeling is based on the assumption that the anomalous electrical field within an inhomogeneous domain is linearly proportional to the background (normal) field through an electrical reflectivity tensor <(<lambda>)over cap>. In the original formulation of the quasi-linear appruximation, <(<lambda>)over cap> was determined by solving a minimization probIem based on an integral equation for the scattering currents. This approach is much less time-consuming than the full integral equation method; however, it still requires solution of the corresponding system of linear equations. In this paper, we present a new approach to the approximate solution of the integral equation using <(<lambda>)over cap> through construction of quasi-analytical expressions for the anomalous electromagnetic held for 3-D and 2-D models. Quasi-analytical solutions reduce dramatically the computational effort related to forward electromagnetic modeling of inhomogeneous geoelectrical structures. In the last sections of this paper, we extend the quasi-analytical method using iterations and develop higher order approximatipns resulting in quasianalytical series which provide improved accuracy. Computation of these series is based on repetitive application of the given integral contraction operator, which insures rapid convergence to the correct result. Numerical studies demonstrate that quasi-analytical series can be treated as a new powerful method of fast but rigorous forward modeling solution.