Browsing by Author "Ergül, Özgür"
Now showing items 1-20 of 79
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Accuracy and efficiency considerations in the solution of extremely large electromagnetics problems
(IEEE, 2011)This study considers fast and accurate solutions of extremely large electromagnetics problems. Surface formulations of large-scale objects lead to dense matrix equations involving millions of unknowns. Thanks to recent ... -
Accurate modeling of metamaterials with MLFMA
(ESA Publications, 2006)Electromagnetic modelling of large metamaterial (MM) structures employing multilevel fast multipole algorithm (MLFMA) is reported. MMs are usually constructed by periodically embedding unit cells, such as split-ring ... -
Accurate solutions of scattering problems involving low-contrast dielectric objects with surface integral equations
(Institution of Engineering and Technology, 2007)We present the stabilization of the surface integral equations for accurate solutions of scattering problems involving low-contrast dielectric objects. Unlike volume formulations, conventional surface formulations fail to ... -
Analysis of composite objects involving multiple dielectric and metallic partswith the parallel multilevel fast multipole algorithm
(Applied Computational Electromagnetics Society, 2012-04) -
Analysis of dielectric photonic-crystal problems with MLFMA and Schur-complement preconditioners
(IEEE, 2011-01-13)We present rigorous solutions of electromagnetics problems involving 3-D dielectric photonic crystals (PhCs). Problems are formulated with recently developed surface integral equations and solved iteratively using the ... -
Analysis of photonic-crystal problems with MLFMA and approximate Schur preconditioners
(IEEE, 2009-07)We consider fast and accurate solutions of electromagnetics problems involving three-dimensional photonic crystals (PhCs). Problems are formulated with the combined tangential formulation (CTF) and the electric and magnetic ... -
Approximate MLFMA as an efficient preconditioner
(IEEE, 2007)In this work, we propose a preconditioner that approximates the dense system operator. For this purpose, we develop an approximate multilevel fast multipole algorithm (AMLFMA), which performs a much faster matrix-vector ... -
Circular arrays of log-periodic antennas for broadband applications
(IEEE, 2006)Circular arrays of log-periodic (LP) antennas are designed for broadband applications. A sophisticated electromagnetic simulation environment involving integral equations and fast solvers is developed to analyze the LP ... -
Combined-field solution of composite geometries involving open and closed conducting surfaces
(IEEE, 2005-04)Combined-field integral equation (CFIE) is modified and generalized to formulate the electromagnetic problems of composite geometries involving both open and closed conducting surfaces. These problems are customarily ... -
Comparison of integral-equation formulations for the fast and accurate solution of scattering problems involving dielectric objects with the multilevel fast multipole algorithm
(Institute of Electrical and Electronics Engineers, 2009)We consider fast and accurate solutions of scattering problems involving increasingly large dielectric objects formulated by surface integral equations. We compare various formulations when the objects are discretized with ... -
Comparisons of FMM implementations employing different formulations and iterative solvers
(IEEE, 2003-06)The implementation of multi-level fast multipole algorithm (MLFMA) requires the consideration of several parameters. The preferred combination of the parameters given is not trivially obvious and requires a careful ... -
Computational analysis of complicated metamaterial structures using MLFMA and nested preconditioners
(IEEE, 2007-11)We consider accurate solution of scattering problems involving complicated metamaterial (MM) structures consisting of thin wires and split-ring resonators. The scattering problems are formulated by the electric-field ... -
Computational study of scattering from healthy and diseased red blood cells
(Society of Photo Optical Instrumentation Engineers, 2010-08-05)We present a comparative study of scattering from healthy red blood cells (RBCs) and diseased RBCs with deformed shapes. Scattering problems involving three-dimensional RBCs are formulated accurately with the electric and ... -
Contamination of the accuracy of the combined-field integral equation with the discretization error of the magnetic-field integral equation
(Institute of Electrical and Electronics Engineers, 2009)We investigate the accuracy of the combined-field integral equation (CFIE) discretized with the Rao-Wilton-Glisson (RWG) basis functions for the solution of scattering and radiation problems involving three-dimensional ... -
Design and simulation of circular arrays of trapezoidal-tooth log-periodic antennas via genetic optimization
(Electromagnetics Academy, 2008)Circular arrays of log-periodic (LP) antennas are designed and their operational properties are investigated in a sophisticated simulation environment that is based on the recent advances in computational electromagnetics. ... -
Discretization error due to the identity operator in surface integral equations
(ELSEVIER, 2009-05-03)We consider the accuracy of surface integral equations for the solution of scattering and radiation problems in electromagnetics. In numerical solutions, second-kind integral equations involving well-tested identity operators ... -
Effective preconditioners for large integral-equation problems
(IET, 2007-11)We consider effective preconditioning schemes for the iterative solution of integral-equation methods. For parallel implementations, the sparse approximate inverse or the iterative solution of the near-field system enables ... -
Efficient parallelization of the multilevel fast multipole algorithm for the solution of large-scale scattering problems
(Institute of Electrical and Electronics Engineers, 2008-08)We present fast and accurate solutions of large-scale scattering problems involving three-dimensional closed conductors with arbitrary shapes using the multilevel fast multipole algorithm (MLFMA). With an efficient ... -
Efficient solution of the combined-field integral equation with the parallel multilevel fast multipole algorithm
(IEEE, 2007-08)We present fast and accurate solutions of large-scale scattering problems formulated with the combined-field integral equation. Using the multilevel fast multipole algorithm (MLFMA) parallelized on a cluster of computers, ... -
Efficient solution of the electric and magnetic current combined‐field integral equation with the multilevel fast multipole algorithm and block‐diagonal preconditioning
(Wiley-Blackwell Publishing, Inc., 2009-12)We consider the efficient solution of electromagnetics problems involving dielectric and composite dielectric-metallic structures, formulated with the electric and magnetic current combined-field integral equation (JMCFIE). ...
