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Author

Bagci, Hakan (48)

Ulku, Huseyin Arda (17)Desmal, Abdulla (10)Sayed, Sadeed Bin (9)Uysal, Ismail Enes (8)View MoreDepartmentComputer, Electrical and Mathematical Sciences and Engineering (CEMSE) Division (48)
Electrical Engineering Program (48)

Computer, Electrical and Mathematical Sciences & Engineering (CEMSE) (34)Physical Sciences and Engineering (PSE) Division (8)Applied Mathematics and Computational Science Program (4)View MoreJournalIEEE Transactions on Antennas and Propagation (2)2016 10th European Conference on Antennas and Propagation (EuCAP) (1)2016 IEEE/ACES International Conference on Wireless Information Technology and Systems (ICWITS) and Applied Computational Electromagnetics (ACES) (1)2017 IEEE 26th Conference on Electrical Performance of Electronic Packaging and Systems (EPEPS) (1)2017 IEEE International Symposium on Antennas and Propagation & USNC/URSI National Radio Science Meeting (1)View MoreKAUST Grant NumberRGC/3/2385-01 (1)PublisherInstitute of Electrical and Electronics Engineers (IEEE) (7)IEEE (3)American Physical Society (APS) (1)arXiv (1)IOP Publishing (1)View MoreSubjectCEM (15)Time-domain analysis (2)Accelerated steepest descent (1)Auxiliary differential equation (ADE) method (1)Born iterative method (1)View MoreTypePoster (32)Article (8)Conference Paper (5)Presentation (2)Preprint (1)Year (Issue Date)2018 (7)2017 (5)2016 (9)2015 (8)2014 (19)Item Availability
Open Access (48)

Now showing items 31-40 of 48

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MOT Solution of Time Domain PMCHWT Integral Equation for Conductive Dielectric Scatterers

Uysal, Ismail Enes; Ulku, Huseyin Arda; Bagci, Hakan (2014-01-06) [Poster]

An Explicit and Stable MOT Solver for Time Domain Volume Electric Field Integral Equation

Sayed, Sadeed Bin; Ulku, Huseyin Arda; Bagci, Hakan (2014-01-06) [Poster]

On the DC Loop Modes in MOT Solution of Time Domain Electric Field Integral Equation

Shi, Yifei; Lu, Mingyu; Bagci, Hakan (2014-01-06) [Poster]

Analysis of Electromagnetic Wave Interactions on Nonlinear Scatterers using Time Domain Volume Integral Equations

Ulku, Huseyin Arda; Sayed, Sadeed Bin; Bagci, Hakan (2015-01-07) [Poster]

An Efficient Explicit Time Marching Scheme for Solving the Time Domain Magnetic Field Volume Integral Equation

Sayed, Sadeed Bin; Ulku, Huseyin Arda; Bagci, Hakan (2015-01-07) [Poster]

A Novel Time Domain Method for Characterizing Plasmonic Field Interactions

Uysal, Ismail Enes; Ulku, Huseyin Arda; Bagci, Hakan (2015-01-07) [Poster]

Sparse Electromagnetic Imaging Using Nonlinear Landweber Iterations

Desmal, Abdulla; Bagci, Hakan (2015-01-07) [Poster]

A Time Marching Scheme for Solving Volume Integral Equations on Nonlinear Scatterers

Bagci, Hakan (2015-01-07) [Presentation]

Transient electromagnetic field interactions on inhomogeneous penetrable scatterers can be analyzed by solving time domain volume integral equations (TDVIEs). TDVIEs are oftentimes solved using marchingon-in-time (MOT) schemes. Unlike finite difference and finite element schemes, MOT-TDVIE solvers require discretization of only the scatterers, do not call for artificial absorbing boundary conditions, and are more robust to numerical phase dispersion. On the other hand, their computational cost is high, they suffer from late-time instabilities, and their implicit nature makes incorporation of nonlinear constitutive relations more difficult. Development of plane-wave time-domain (PWTD) and FFT-based schemes has significantly reduced the computational cost of the MOT-TDVIE solvers. Additionally, latetime instability problem has been alleviated for all practical purposes with the development of accurate integration schemes and specially designed temporal basis functions. Addressing the third challenge is the topic of this presentation. I will talk about an explicit MOT scheme developed for solving the TDVIE on scatterers with nonlinear material properties. The proposed scheme separately discretizes the TDVIE and the nonlinear constitutive relation between electric field intensity and flux density. The unknown field intensity and flux density are expanded using half and full Schaubert-Wilton-Glisson (SWG) basis functions in space and polynomial temporal interpolators in time. The resulting coupled system of the discretized TDVIE and constitutive relation is integrated in time using an explicit P E(CE) m scheme to yield the unknown expansion coefficients. Explicitness of time marching allows for straightforward incorporation of the nonlinearity as a function evaluation on the right hand side of the coupled system of equations. Consequently, the resulting MOT scheme does not call for a Newton-like nonlinear solver. Numerical examples, which demonstrate the applicability of the proposed MOT scheme to analyzing electromagnetic interactions on Kerr-nonlinear scatterers will be presented.

A Highly Stable Marching-on-in-Time Volume Integral Equation Solver for Analyzing Transient Wave Interactions on High-Contrast Scatterers

Bagci, Hakan (2014-01-06) [Presentation]

Time domain integral equation (TDIE) solvers represent an attractive alternative to finite difference (FDTD) and finite element (FEM) schemes for analyzing transient electromagnetic interactions on composite scatterers. Current induced on a scatterer, in response to a transient incident field, generates a scattered field. First, the scattered field is expressed as a spatio-temporal convolution of the current and the Green function of the background medium. Then, a TDIE is obtained by enforcing boundary conditions and/or fundamental field relations. TDIEs are often solved for the unknown current using marching on-in-time (MOT) schemes. MOT-TDIE solvers expand the current using local spatio-temporal basis functions. Inserting this expansion into the TDIE and testing the resulting equation in space and time yields a lower triangular system of equations (termed MOT system), which can be solved by marching in time for the coefficients of the current expansion. Stability of the MOT scheme often depends on how accurately the spatio-temporal convolution of the current and the Green function is discretized. In this work, band-limited prolate-based interpolation functions are used as temporal bases in expanding the current and discretizing the spatio-temporal convolution. Unfortunately, these functions are two sided, i.e., they require ”future” current samples for interpolation, resulting in a non-causal MOT system. To alleviate the effect of non-causality and restore the ability to march in time, an extrapolation scheme can be used to estimate the future values of the currents from their past values. Here, an accurate, stable and band-limited extrapolation scheme is developed for this purpose. This extrapolation scheme uses complex exponents, rather than commonly used harmonics, so that propagating and decaying mode fields inside the dielectric scatterers are accurately modeled. The resulting MOT scheme is applied to solving the time domain volume integral equation (VIE). Numerical results demonstrate that this new MOT-VIE solver maintains its stability and accuracy even when used in analyzing transient wave interactions on high-contrast scatterers.

Computation of Electromagnetic Fields Scattered From Dielectric Objects of Uncertain Shapes Using MLMC

Litvinenko, Alexander; Haji Ali, Abdul Lateef; Uysal, Ismail Enes; Ulku, Huseyin Arda; Tempone, Raul; Bagci, Hakan; Oppelstrup, Jesper (2015-01-07) [Poster]

Simulators capable of computing scattered fields from objects of uncertain shapes are highly useful in electromagnetics and photonics, where device designs are typically subject to fabrication tolerances. Knowledge of statistical variations in scattered fields is useful in ensuring error-free functioning of devices. Oftentimes such simulators use a Monte Carlo (MC) scheme to sample the random domain, where the variables parameterize the uncertainties in the geometry. At each sample, which corresponds to a realization of the geometry, a deterministic electromagnetic solver is executed to compute the scattered fields. However, to obtain accurate statistics of the scattered fields, the number of MC samples has to be large.
This significantly increases the total execution time. In this work, to address this challenge, the Multilevel MC (MLMC [1]) scheme is used together with a (deterministic) surface integral equation solver. The MLMC achieves a higher efficiency by “balancing” the statistical errors due to sampling of the random domain and the numerical errors due to discretization of the geometry at each of these samples. Error balancing results in a smaller number of samples requiring coarser discretizations. Consequently, total execution time is significantly shortened.

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