Optimal control approach for the solution of electromagnetic inverse scattering problems.

Optimal Cavities to Enhance Free-space Matching in Solar Cells Karaosmanoglu, B.; Topcuoglu, U.; Guler, S.; Tuygar, E.; Ergül, Özgür Salih (2018-08-04) In this paper, we present design and numerical simulations of nano-cavities for free space matching in solar cells at optical frequencies. The cavity designs are inspired by the wellknown antenna geometries that are commonly used at radio and microwave frequencies. Using such designs that have not been explored before in the context of solar cells, the electromagnetic mismatch between solar-cell surfaces and vacuum is significantly reduced, in comparison to planar interfaces and those with the conventional ...
Accurate analysis of metamaterials involving finite arrays of split-ring resonators and thin wires Gurel, Levent; Ergül, Özgür Salih; Unal, Alper (2007-03-30) In order to gain physical insight into how some metamaterial structures behave, we report our results obtained by accurate numerical solutions of electromagnetic problems related to various constructions of split-ring-resonators (SRRs) and thin wires (TWs). Single and multiple layers of arrays of SRRs and TWs are investigated in detail using the electric-field integral equation. Without utilizing any homogenization techniques, we accurately model large numbers of unit cells that translate into very large co...
Multi-frequency contactless electrical impedance imaging using realistic head models : single coil simulations Gürsoy, Doğa; Ertan, Hulusi Bülent; Department of Electrical and Electronics Engineering (2007) Contactless electrical impedance imaging technique is based upon the measurement of secondary electromagnetic fields caused by induced currents inside the body. In this study, a circular single-coil is used as a transmitter and a receiver. The purpose of this study is twofold: (1) to solve the induced current density distribution inside the realistic head model resulting from a sinusoidal excitation, (2) to calculate the impedance change of the same coil from the induced current distribution inside the head...
Scalar waves in spacetimes with closed timelike curves Buğdaycı, Necmi; Başkal, Sibel; Department of Physics (2005) The existence and -if exists- the nature of the solutions of the scalar wave equation in spacetimes with closed timelike curves are investigated. The general properties of the solutions on some class of spacetimes are obtained. Global monochromatic solutions of the scalar wave equation are obtained in flat wormholes of dimensions 2+1 and 3+1. The solutions are in the form of infinite series involving cylindirical and spherical wave functions and they are elucidated by the multiple scattering method. Explici...
Improved Nano-optical Traps for Single-particle Sensing Applications Isiklar, G.; Algun, M.; Ergül, Özgür Salih (2019-01-01) We present numerical design and simulations of nano-optical traps for single-particle sensing applications. While commonly used nano-holes with circular shapes are suitable for physically trapping nanoparticles to be detected and identified, they generate relatively weak signals in the far zone, especially when nanoparticles are small. We show that optical sensitivity of nano-holes can be enhanced significantly by using well-designed tip geometries such that metallic and dielectric nanoparticles can be dete...

Citation Formats

M. Önder, “Optimal control approach for the solution of electromagnetic inverse scattering problems.,” Ph.D. - Doctoral Program, Middle East Technical University, 1993.