Browsing by Author "Ergül, Özgür"
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Efficient solution of the electricfield integral equation using the iterative LSQR algorithm
Ergül, Özgür; Gürel, Levent (Institute of Electrical and Electronics Engineers, 2008)In this letter, we consider iterative solutions of the threedimensional electromagnetic scattering problems formulated by surface integral equations. We show that solutions of the electricfield integral equation (EFIE) ... 
Efficient solutions of metamaterial problems using a lowfrequency multilevel fast multipole algorithm
Ergül, Özgür; Gürel, Levent (2010)We present fast and accurate solutions of electromagnetics problems involving realistic metamaterial structures using a lowfrequency multilevel fast multipole algorithm (LFMLFMA). Accelerating iterative solutions using ... 
Efficient surface integral equation methods for the analysis of complex metamaterial structures
YlaOijala, P.; Ergül, Özgür; Gürel, Levent; Taskinen, M. (IEEE, 2009)Two approaches, the multilevel fast multipole algorithm with sparse approximate inverse preconditioner and the surface equivalence principle algorithm, are applied to analyze complex threedimensional metamaterial structures. ... 
Electromagnetic modeling of splitring resonators
Gürel, Levent; Ünal, Alper; Ergül, Özgür (IEEE, 2007)In this paper, we report our efforts to model splitring resonators (SRRs) and their large arrays accurately and efficiently in a sophisticated simulation environment based on recent advances in the computational electromagnetics. ... 
Enhancing the accuracy of the interpolations and anterpolations in MLFMA
Ergül, Özgür; Gürel, Levent (Institute of Electrical and Electronics Engineers, 2006)We present an efficient technique to reduce the interpolation and anterpolation (transpose interpolation) errors in the aggregation and disaggregation processes of the multilevel fast multipole algorithm (MLFMA), which is ... 
Extending the applicability of the combinedfield integral equation to geometries containing open surfaces
Gürel, Levent; Ergül, Özgür (Institute of Electrical and Electronics Engineers, 2006)In this letter, we consider the solution of large electromagnetics problems of composite structures with coexisting open and closed conductors. By modifying the construction of the combinedfield integral equation (CFIE), ... 
Fast and accurate analysis of complicated metamaterial structures using a lowfrequency multilevel fast multipole algorithm
Ergül, Özgür; Gürel, Levent (200909)We present efficient solutions of electromagnetics problems involving realistic metamaterial structures using a lowfrequency multilevel fast multipole algorithm (LFMLFMA). Ordinary implementations of MLFMA based on the ... 
Fast and accurate analysis of large metamaterial structures using the multilevel fast multipole algorithm
Gürel, Levent; Ergül, Özgür; Ünal, A.; Malas, T. (2009)We report fast and accurate simulations of metamaterial structures constructed with large numbers of unit cells containing splitring resonators and thin wires. Scattering problems involving various metamaterial walls are ... 
Fast and accurate analysis of largescale composite structures with the parallel multilevel fast multipole algorithm
Ergül, Özgür; Gürel, Levent (Optical Society of America, 2013)Accurate electromagnetic modeling of complicated optical structures poses several challenges. Optical metamaterial and plasmonic structures are composed of multiple coexisting dielectric and/or conducting parts. Such ... 
Fast and accurate analysis of optical metamaterials using surface integral equations and the parallel multilevel fast multipole algorithm
Ergül, Özgür; Gürel, Levent (IEEE, 2013)We present fast and accurate simulations of optical metamaterials using surface integral equations and the multilevel fast multipole algorithm (MLFMA). Problems are formulated with the electric and magnetic current ... 
Fast and accurate solutions of extremely large integralequation problems discretised with tens of millions of unknowns
Gürel, Levent; Ergül, Özgür (The Institution of Engineering and Technology, 2007)The solution of extremely large scattering problems that are formulated by integral equations and discretised with tens of millions of unknowns is reported. Accurate and efficient solutions are performed by employing a ... 
Fast and accurate solutions of extremely large scattering problems involving threedimensional canonical and complicated objects
Ergül, Özgür; Gürel, Levent (IEEE, 200907)We present fast and accurate solutions of extremely large scattering problems involving threedimensional metallic objects discretized with hundreds of millions of unknowns. Solutions are performed by the multilevel fast ... 
Fast and accurate solutions of largescale scattering problems with parallel multilevel fast multipole algorithm
Ergül, Özgür; Gürel, Levent (IEEE, 2007)Fast and accurate solution of largescale scattering problems obtained by integralequation formulations for conducting surfaces is considered in this paper. By employing a parallel implementation of the multilevel fast ... 
Fast and accurate solutions of scattering problems involving dielectric objects with moderate and low contrasts
Ergül, Özgür; Gürel, Levent (IEEE, 200708)We consider the solution of electromagnetic scattering problems involving relatively large dielectric objects with moderate and low contrasts. Threedimensional objects are discretized with RaoWiltonGlisson functions and ... 
Hierarchical parallelisation strategy for multilevel fast multipole algorithm in computational electromagnetics
Ergül, Özgür; Gürel, Levent (The Institution of Engineering and Technology, 2008)A hierarchical parallelisation of the multilevel fast multipole algorithm (MLFMA) for the efficient solution of largescale problems in computational electromagnetics is presented. The tree structure of MLFMA is distributed ... 
Hierarchical parallelization of the multilevel fast multipole algorithm (MLFMA)
Gürel, Levent; Ergül, Özgür (IEEE, 2013)Due to its O(N log N) complexity, the multilevel fast multipole algorithm (MLFMA) is one of the most prized algorithms of computational electromagnetics and certain other disciplines. Various implementations of this algorithm ... 
Hierarchical parallelization of the multilevel fast multipole algorithm for the efficient solution of largescale scattering problems
Ergül, Özgür; Gürel, Levent (IEEE, 200807)We present the details of a hierarchical parallelization strategy, which provides higher efficiency than the previous parallelization approaches for MLFMA. We demonstrate the effectiveness of our algorithm on sphere problems ... 
A hierarchical partitioning strategy for an efficient parallelization of the multilevel fast multipole algorithm
Ergül, Özgür; Gürel, Levent (IEEE, 2009)We present a novel hierarchical partitioning strategy for the efficient parallelization of the multilevel fast multipole algorithm (MLFMA) on distributedmemory architectures to solve largescale problems in electromagnetics. ... 
Hybrid CFIEEFIE solution of composite geometries with coexisting open and closed surfaces
Ergül, Özgür; Gürel, Levent (IEEE, 2005)The combinedfield integral equation (CFIE) is employed to formulate the electromagnetic scattering and radiation problems of composite geometries with coexisting open and closed conducting surfaces. Conventional formulations ... 
Hybridizing physical optics with MLFMA for efficient scattering computations of threedimensional complex targets
Manyas, Alp; Ergül, Özgür; Gürel, Levent (IEEE, 200907)The multilevel fast multipole algorithm (MLFMA) provides accurate and efficient solutions of electromagnetic scattering problems involving large and complicated structures. On the other hand, whenever applicable, accelerations ...