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Author

Bagci, Hakan (8)

Ulku, Huseyin Arda (6)Uysal, Ismail Enes (3)Li, Peng (2)Sayed, Sadeed Bin (2)View MoreDepartment
Computer, Electrical and Mathematical Sciences and Engineering (CEMSE) Division (8)

Electrical Engineering Program (8)

Physical Sciences and Engineering (PSE) Division (8)

Computer, Electrical and Mathematical Sciences & Engineering (CEMSE) (5)Materials Science and Engineering Program (2)View MoreJournal2016 IEEE/ACES International Conference on Wireless Information Technology and Systems (ICWITS) and Applied Computational Electromagnetics (ACES) (1)ChemElectroChem (1)IEEE Antennas and Wireless Propagation Letters (1)PublisherInstitute of Electrical and Electronics Engineers (IEEE) (2)Wiley (1)SubjectCEM (3)Buffa-Christiansen functions (1)constant phase angle (1)constant phase element (1)constant phase zone (1)View MoreTypePoster (5)Article (2)Conference Paper (1)Year (Issue Date)2017 (2)2016 (4)2015 (2)Item Availability
Open Access (8)

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A Hybrid DGTD-MNA Scheme for Analyzing Complex Electromagnetic Systems

Li, Peng; Jiang, Li-Jun; Bagci, Hakan (2015-01-07) [Poster]

A hybrid electromagnetics (EM)-circuit simulator for analyzing complex systems consisting of EM devices loaded with nonlinear multi-port lumped circuits is described. The proposed scheme splits the computational domain into two subsystems: EM and circuit subsystems, where field interactions are modeled using Maxwell and Kirchhoff equations, respectively. Maxwell equations are discretized using a discontinuous Galerkin time domain (DGTD) scheme while Kirchhoff equations are discretized using a modified nodal analysis (MNA)-based scheme. The coupling between the EM and circuit subsystems is realized at the lumped ports, where related EM fields and circuit voltages and currents are allowed to “interact’’ via numerical flux. To account for nonlinear lumped circuit elements, the standard Newton-Raphson method is applied at every time step. Additionally, a local time-stepping scheme is developed to improve the efficiency of the hybrid solver. Numerical examples consisting of EM systems loaded with single and multiport linear/nonlinear circuit networks are presented
to demonstrate the accuracy, efficiency, and applicability of the proposed solver.

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; Oppelstrup, Jesper; Tempone, Raul; Bagci, Hakan (2016-01-06) [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.

Transient Analysis of Electromagnetic Wave Interactions on Ferromagnetic Structures Using Landau-Lifshitz-Gilbert and Volume Integral Equations

Sayed, Sadeed Bin; Ulku, Huseyin Arda; Bagci, Hakan (2016-01-06) [Poster]

Mixed Discretization of the Time Domain MFIE at Low Frequencies

Ulku, Huseyin Arda; Bogaert, Ignace; Cools, Kristof; Andriulli, Francesco Paolo; Bagci, Hakan (IEEE Antennas and Wireless Propagation Letters, Institute of Electrical and Electronics Engineers (IEEE), 2017-01-10) [Article]

Solution of the magnetic field integral equation (MFIE), which is obtained by the classical marching on-in-time (MOT) scheme, becomes inaccurate when the time step is large, i.e., under low-frequency excitation. It is shown here that the inaccuracy stems from the classical MOT scheme’s failure to predict the correct scaling of the current’s Helmholtz components for large time steps. A recently proposed mixed discretization strategy is used to alleviate the inaccuracy problem by restoring the correct scaling of the current’s Helmholtz components under low-frequency excitation.

An Explicit MOT-TD-VIE Solver for Time Varying Media

Sayed, Sadeed Bin; Ulku, Huseyin Arda; Bagci, Hakan (2016 IEEE/ACES International Conference on Wireless Information Technology and Systems (ICWITS) and Applied Computational Electromagnetics (ACES), Institute of Electrical and Electronics Engineers (IEEE), 2016-03-15) [Conference Paper]

An explicit marching on-in-time (MOT) scheme for solving the time domain electric field integral equation enforced on volumes with time varying dielectric permittivity is proposed. Unknowns of the integral equation and the constitutive relation, i.e., flux density and field intensity, are discretized using full and half Schaubert-Wilton-Glisson functions in space. Temporal interpolation is carried out using band limited approximate prolate spherical wave functions. The discretized coupled system of integral equation and constitutive relation is integrated in time using a PE(CE)m type linear multistep scheme. Unlike the existing MOT methods, the resulting explicit MOT scheme allows for straightforward incorporation of the time variation in the dielectric permittivity.

Analysis of Transient Electromagnetic Wave Interactions on Graphene Sheets Using Integral Equations

Shi, Yifei; Sandhu, Ali Imran; Li, Peng; Uysal, Ismail Enes; Ulku, Huseyin Arda; Bagci, Hakan (2015-01-07) [Poster]

Analysis of Transient Electromagnetic Interactions on Nanodevices Using a Quantum-corrected Integral Equation Approach

Uysal, Ismail Enes; Ulku, Huseyin Arda; Bagci, Hakan (2016-01-06) [Poster]

Ferroelectric Fractional-Order Capacitors

Agambayev, Agamyrat; Patole, Shashikant P.; Farhat, Mohamed; Elwakil, Ahmed S.; Bagci, Hakan; Salama, Khaled N. (ChemElectroChem, Wiley, 2017-07-25) [Article]

Poly(vinylidene fluoride)-based polymers and their blends are used to fabricate electrostatic fractional-order capacitors. This simple but effective method allows us to precisely tune the constant phase angle of the resulting fractional-order capacitor by changing the blend composition. Additionally, we have derived an empirical relation between the ratio of the blend constituents and the constant phase angle to facilitate the design of a fractional order capacitor with a desired constant phase angle. The structural composition of the fabricated blends is investigated using Fourier transform infrared spectroscopy and X-ray diffraction techniques.

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