Adjoint Based Sampling Methods for Electromagnetic Scattering
نویسندگان
چکیده
In this paper we investigate the efficient realization of sampling methods, based on solutions of certain adjoint problems. This adjoint approach does not require the explicit knowledge of a Green’s function for the background medium, and allows to sample for all points and all dipole directions simultaneously; thus several limitations of standard sampling methods are relieved. A detailed derivation of the adjoint approach is presented for two electromagnetic model problems, but the framework can be applied to a much wider class of problems. We also discuss a relation of the adjoint sampling method to standard backprojection algorithms, and present numerical tests that illustrate the efficiency of the adjoint approach.
منابع مشابه
Importance Sampling and Adjoint Hybrid Methods in Monte Carlo Transport with Reflecting Boundaries
Adjoint methods form a class of importance sampling methods that are used to accelerate Monte Carlo (MC) simulations of transport equations. Ideally, adjoint methods allow for zero-variance MC estimators provided that the solution to an adjoint transport equation is known. Hybrid methods aim at (i) approximately solving the adjoint transport equation with a deterministic method; and (ii) use th...
متن کاملA pr 2 00 7 A Rigorous Time - Domain Analysis of Full – Wave Electromagnetic Cloaking ( Invisibility ) ∗ †
There is currently a great deal of interest in the theoretical and practical possibility of cloaking objects from the observation by electromagnetic waves. The basic idea of these invisibility devices [8, 9, 13], [18] is to use anisotropic transformation media whose permittivity and permeability ε , μ, are obtained from the ones, ε 0 , μ λν 0 , of isotropic media, by singular transformations of...
متن کاملF eb 2 00 8 A Rigorous Time - Domain Analysis of Full – Wave Electromagnetic Cloaking ( Invisibility ) ∗ †
There is currently a great deal of interest in the theoretical and practical possibility of cloaking objects from the observation by electromagnetic waves. The basic idea of these invisibility devices [8, 9, 13], [18] is to use anisotropic transformation media whose permittivity and permeability ε , μ, are obtained from the ones, ε 0 , μ λν 0 , of isotropic media, by singular transformations of...
متن کاملA Direct Sampling Method for Inverse Electromagnetic Medium Scattering
In this paper, we study the inverse electromagnetic medium scattering problem of estimating the support and shape of medium scatterers from scattered electric/magnetic near-field data. We shall develop a novel direct sampling method based on an analysis of electromagnetic scattering and the behavior of the fundamental solution. It is applicable to a few incident fields and needs only to compute...
متن کاملA shape reconstruction method for electromagnetic tomography using adjoint elds and level sets
A two-step shape reconstruction method for electromagnetic (EM) tomography is presented which uses adjoint elds and level sets. The inhomogeneous background permittivity distribution and the values of the permittivities in some penetrable obstacles are assumed to be known, and the number, sizes, shapes, and locations of these obstacles have to be reconstructed given noisy limited-view EM data. ...
متن کامل