Electromagnetic Problems (electromagnetic + problem)

Distribution by Scientific Domains


Selected Abstracts


Solving inverse electromagnetic problems using FDTD and gradient-based minimization

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 6 2006
Erik Abenius
Abstract We address time-domain inverse electromagnetic scattering for determining unknown characteristics of an object from observations of the scattered field. Applications include non-destructive characterization of media and optimization of material properties, for example, the design of radar absorbing materials. Another application is model reduction where a detailed model of a complex geometry is reduced to a simplified model. The inverse problem is formulated as an optimal control problem where the cost function to be minimized is the difference between the estimated and observed fields, and the control parameters are the unknown object characteristics. The problem is solved in a deterministic gradient-based optimization algorithm using a parallel 2D FDTD scheme. Highly accurate analytical gradients are computed from the adjoint formulation. The inverse method is applied to the characterization of layered dispersive media and the determination of parameters in subcell models for thin sheets and narrow slots. Copyright 2006 John Wiley & Sons, Ltd. [source]


Equivalent circuit representation for integral formulations of electromagnetic problems

INTERNATIONAL JOURNAL OF NUMERICAL MODELLING: ELECTRONIC NETWORKS, DEVICES AND FIELDS, Issue 1 2002
H. Baudrand
The purpose of this study is to investigate the resources offered by electromagnetic equivalent circuits as a tool for the systematic derivation of integral equations and also, to propose consistent models for active sources. Copyright 2002 John Wiley & Sons, Ltd. [source]


Surrogate-based infill optimization applied to electromagnetic problems

INTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 5 2010
I. Couckuyt
Abstract The increasing use of expensive computer simulations in engineering places a serious computational burden on associated optimization problems. Surrogate-based optimization becomes standard practice in analyzing such expensive black-box problems. This article discusses several approaches that use surrogate models for optimization and highlights one sequential design approach in particular, namely, expected improvement. The expected improvement approach is demonstrated on two electromagnetic problems, namely, a microwave filter and a textile antenna. 2010 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2010. [source]


Robust GMRES recursive method for fast finite element analysis of 3D electromagnetic problems

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 5 2007
P. L. Rui
Abstract A robust generalized minimal residual recursive (GMRESR) iterative method is proposed to solve a large system of linear equations resulting from the use of an un-gauged vector-potential formulation of finite element method (FEM). This method involves an outer generalized conjugate residual (GCR) method and an inner generalized minimal residual (GMRES) method, where the inner GMRES acts as a variable preconditioning for the outer GCR. The efficient implementation of symmetric successive overrelaxation (SSOR) preconditioned GMRESR (SSOR-GMRESR) algorithm is described in details for complex coefficient matrix equation. On several three-dimensional electromagnetic problems, the resulting SSOR-GMRESR approach converges in CPU time, which is 14.2,71.3 times shorter with respect to conventional conjugate gradient (CG) approach. By comparison with other popularly preconditioned CG methods, the results demonstrate that SSOR-GMRESR is especially effective and robust when the A-V formulation of FEM is applied to solve large-scale time harmonic electromagnetic field problems. 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1010,1015, 2007; Published online in Wiley InterScience (www.interscience.wiley.com).DOI 10.1002/mop.22333 [source]


Further comments on the performances of finite element simulators for the solution of electromagnetic problems involving metamaterials

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 12 2006
Gaia Cevini
Abstract In this paper, we analyze the performances of three-dimensional finite element (FE) simulators in handling electromagnetic scattering problems involving metamaterials. It has already been proved that the performances of the FE method are worse than usual, when metamaterials are considered. In this work, we extend our previous analysis by providing some additional results on the precision of the FE solution and on the performances of the iterative and direct solvers typically used with FE simulators. 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48:2524,2529, 2006; Published online in Wiley InterScience (www.interscience.wiley.com).DOI 10.1002/mop.22008 [source]


Sparse solution of an integral equation formulation of scattering from open PEC targets

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 3 2006
A. Zhu
Abstract A recently developed compression and sparse solution strategy for electromagnetic problems is applied to integral-equation formulations of scattering from perfectly conducting targets in three dimensions. It is shown that the resulting representations of both the impedance matrix and its inverse are sparse at low-to-moderate frequencies. Limitations and possible extensions of the sparse algorithms are also discussed. 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 476,480, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21383 [source]