Georgios G. Pyrialakos

A curvilinear stochastic-FDTD algorithm for 3-D EMC problems with media uncertainties

Purpose – Stochastic uncertainties in material parameters have a significant impact on the analysis of real-world electromagnetic compatibility (EMC) problems. Conventional approaches via the Monte-Carlo scheme attempt to provide viable solutions, yet at the expense of prohibitively elongated simulations and system overhead, due to the large amount of statistical implementations. The purpose of this paper is to introduce a 3-D stochastic finite-difference time-domain (S-FDTD) technique for the accurate modelling of generalised EMC applications with highly random media properties, while concurrently offering fast and economical single-run realisations. Design/methodology/approach – The proposed method establishes the concept of covariant/contravariant metrics for robust tessellations of arbitrarily curved structures and derives the mean value and standard deviation of the generated fields in a single-run. Also, the critical case of geometrical and physical uncertainties is handled via an optimal parameteri...

Accelerated unconditionally stable FDTD scheme with modified operators

Purpose – The locally one-dimensional (LOD) finite-difference time-domain (FDTD) method features unconditional stability, yet its low accuracy in time can potentially become detrimental. Regarding the improvement of the method’s reliability, existing solutions introduce high-order spatial operators, which nevertheless cannot deal with the augmented temporal errors. The purpose of the paper is to describe a systematic procedure that enables the efficient implementation of extended spatial stencils in the context of the LOD-FDTD scheme, capable of reducing the combined space-time flaws without additional computational cost. Design/methodology/approach – To accomplish the goal, the authors introduce spatial derivative approximations in parametric form, and then construct error formulae from the update equations, once they are represented as a one-stage process. The unknown operators are determined with the aid of two error-minimization procedures, which equally suppress errors both in space and time. Further...

Design of nanocomposite EMC structures via unconditionally-stable nonstandard time-domain schemes and efficient GPU implementation

A consistent time-domain methodology for the systematic design and broadband assessment of complicated nanos- tructured EMC devices is introduced in this paper. The novel technique combines a family of nonstandard locally one- dimensional finite-difference time-domain schemes with the advanced features of contemporary graphics processor units in general curvilinear coordinates which preserve the hyperbolic profile of Maxwells laws. In this way, the resulting formulation remains completely explicit and generates effective dual meshes free of artificial vector parasites or spurious modes, while the frequency-dependent attributes of every setup are successfully modelled. Numerical results reveal the significant reduction of dispersion errors along with the considerable speedup compared to serialised realisations through various fabric/epoxy devices with nanocomposite media.

Parameter Estimation for Dielectric Media Variations Based on the FDTD Method and the Monge–Kantorovich Mass Transfer Problem

An efficient and consistent methodology is developed in this paper for the precise evaluation of unknown dielectric permittivity media parameters involved in the design of 3-D waveguide structures. In essence, the selected configuration is numerically solved for a set of predetermined permittivity values by means of a time-domain (herein, the finite-difference time-domain) technique at least twice, depending on the desired level of accuracy. Finally, implementing the Monge–Kantorovich mass transfer problem formulation, the required fields are rigorously evaluated for a broader range of values, as substantiated by the results obtained from various realistic arrangements.

Waveguide optimization for dielectric media variation based on the FDTD method and the Monge-Kantorovich mass transfer problem

An efficient methodology is developed to analyze 3-D waveguide structures when their dielectric permittivity parameters are unknown or under optimization. Mainly, the configuration is numerically solved for a set of predetermined permittivity values through a time-domain (herein the FDTD) technique at least twice, depending on the desired accuracy. Finally, using a mass transfer problem formulation, the desired fields are rigorously evaluated for a broader range of values, as substantiated by several results.