Browsing by Subject "Conducting objects"

Now showing 1 - 5 of 5

Open Access
Improving iterative solutions of the electric-field integral equation via transformations into normal equations
(Taylor and Francis, 2012-04-03) Ergül, Özgür; Gürel, Levent
We consider the solution of electromagnetics problems involving perfectly conducting objects formulated with the electric-field integral equation (EFIE). Dense matrix equations obtained from the discretization of EFIE are solved iteratively by the generalized minimal residual (GMRES) algorithm accelerated with a parallel multilevel fast multipole algorithm. We show that the number of iterations is halved by transforming the original matrix equations into normal equations. This way, memory required for the GMRES algorithm is reduced by more than 50%, which is significant when the problem size is large.
Open Access
Microwave imaging of three-dimensional conducting objects using the newton minimization approach
(IEEE, 2013) Etminan, A.; Gürel, Levent
In this work, we present a framework to detect the shape of unknown perfect electric conducting objects by using inverse scattering and microwave imaging. The initialguess object, which evolves to achieve the target, is modeled by triangles such that vertices of the triangles are the unknowns of our problem.
Open Access
Shape reconstruction of three-dimensional conducting objects via near-field measurements
(IEEE, 2014) Etminan, Aslan; Gürel, Levent
A general framework for the shape reconstruction of conducting objects is presented with the Newton minimization approach. Using a fully numerical method, the initial-guess object is evolved to reconstruct the target. The object is modeled by triangles such that the vertices are the unknowns of the inverse-scattering problem. The cost function is minimized as the evolving object converges to the actual target in merely tens of iterations.
Open Access
Solution of large-scale scattering problems with the multilevel fast multipole algorithm parallelized on distributed-memory architectures
(IEEE, 2007) Ergül, Özgür; Gürel, Levent
We present the solution of large-scale scattering problems involving three-dimensional closed conducting objects with arbitrary shapes. With an efficient parallelization of the multilevel fast multipole algorithm on relatively inexpensive computational platforms using distributed-memory architectures, we perform the iterative solution of integral-equation formulations that are discretized with tens of millions of unknowns. In addition to canonical problems, we also present the solution of real-life problems involving complicated targets with large dimensions.
Open Access
Solutions of large-scale electromagnetics problems using an iterative inner-outer scheme with ordinary and approximate multilevel fast multipole algorithms
(2010) Ergül, A.; Malas, T.; Gürel, Levent
We present an iterative inner-outer scheme for the efficient solution of large-scale electromagnetics problems involving perfectly-conducting objects formulated with surface integral equations. Problems are solved by employing the multilevel fast multipole algorithm (MLFMA) on parallel computer systems. In order to construct a robust preconditioner, we develop an approximate MLFMA (AMLFMA) by systematically increasing the efficiency of the ordinary MLFMA. Using a flexible outer solver, iterative MLFMA solutions are accelerated via an inner iterative solver, employing AMLFMA and serving as a preconditioner to the outer solver. The resulting implementation is tested on various electromagnetics problems involving both open and closed conductors. We show that the processing time decreases significantly using the proposed method, compared to the solutions obtained with conventional preconditioners in the literature.