Large-scale Electromagnetic Computation For Modeling And Applications

The papers in this special issue are devoted to the topic of large-scale electromagnetic computation methods for modeling and applicatoins. © 1963-2012 IEEE

Reducing Computational Workload Of Electromagnetic Scattered Fields From Electrically Large Quadratic Surface At High Frequency

We use the numerical steepest descent path (NSDP) method to calculate the highly oscillatory physical optics (PO) scattered fields on electrically large quadratic surfaces. The resultant phase behaviors of PO integrands are elliptic and hyperbolic on parabolic and saddle quadratic patches, respectively. The proposed method relies on deforming the integration path of the PO integral into the NSDPs on the complex plane. Numerical results of the PO scattered fields on these smooth conducting quadratic surfaces illustrate that the proposed NSDP method gains high accuracy while the workload is frequency independent. © 2013 IEEE

The Fast Contour Deformation Method For Calculating The High Frequency Scattered Field From The Fock Current On The Convex Scatterer

In this paper, the Fock current from the 3-D convex cylinder is considered. By using the incremental length diffraction coefficient technique (ILDC), the resultant high frequency scattered fields are expressed in terms of the Fock current from convex scatterer. To efficiently solve the scattered fields, we propose the efficient NSDP method. Numerical examples from the convex cylinder scatterer illustrate that the proposed NSDP method for calculating the high frequency scattered fields could achieve the frequency independent computational workload and error controllable accuracy

A Novel Coordinate Transformation Based Self-coupling Computation Approach For The Method Of Moments

A new highly accurate and efficient coordinate transformation algorithm is proposed for the evaluation of the self-coupling in the Method of Moments (MoM), which produces usually the strongest contributions to the MoM system matrices. The new algorithm provides an effective solution to remove the singularity due to the Green\u27s function inside the self-couplings. Moreover, the new solution reduces the integral dimension from 4-D to 1-D. Thus, better accuracy and efficiency are obtained for the self-coupling integrals

Differential-forms-motivated Discretizations Of Electromagnetic Differential And Integral Equations

In this letter, we present a differential-forms-motivated procedure to unify and guide discretizations of differential and integral equations in computational electromagnetics (CEM). In order to solve such equations accurately, it is crucial to find an appropriate matrix representation of the governing differential or integral operator. Differential forms theory inspires a general procedure of selecting both expansion and test functions wisely. Many well-functioning discretizations in finite element method (FEM) and boundary element method (BEM) can be reinterpreted with this theory. Moreoever, our approach offers guidance for discretizing complicated problems where straightforward discretizations may not be available. © 2014 IEEE

An Efficiently Preconditioned Eigenanalysis Of Inhomogeneously Loaded Rectangular Cavities

In this letter, we demonstrate an efficient preconditioning scheme for the eigenanalysis of inhomogeneously loaded rectangular cavities. Modeling the entire structure with the finite-difference frequency-domain (FDFD) method yields a large sparse eigenvalue problem. The desired interior eigen-spectrum is sought for by Arnoldi iterations with the shift-and-invert operation, where the inversion can only be performed iteratively in large-scale applications. A preconditioner is constructed to speed up the inversion. It can effectively shrink the spectrum of the governing matrix and can be solved for by using fast discrete sine and cosine transforms (DSTs and DCTs). Several numerical examples are included to illustrate the efficiency of the preconditioned eigenanalysis. © 2013 IEEE

The Contour Deformation Method For Calculating The High-Frequency Scattered Field By The Fock Current On The Surface Of The 3-D Convex Cylinder

In this paper, the high-frequency diffracted waves like the creeping waves are comprehensively analyzed by the Fock currents. On invoking the contour deformation method, the highly oscillatory Fock currents are efficiently calculated. Furthermore, the workload for the calculation of Fock currents is frequency-independent. To capture the high-frequency wave physics phenomenon, the Fock current is separated into the classical physical optics (PO) current and the nonuniform (NU)-Fock current along the shadow boundary and in the deep shadow region. To calculate the highly oscillatory scattered wave fields from the Fock current, quadratic approximations of the phase functions in the integrand are adopted. On invoking the numerical steepest descent path (NSDP) method, the scattered wave fields are efficiently calculated with frequency-independent computational effort and error controllable accuracy in each frequency-independent segment. Meanwhile, the high-frequency creeping wave coming from the NU-Fock current is efficiently captured by the NSDP method. Numerical results for the Fock currents, the high-frequency NU-diffracted and scattered far fields on the convex cylinders are given to validate the efficiency of the proposed method. Furthermore, the contour deformation method for computing the Fock currents offers a clear physical picture for the high-frequency wave fields on the convex scatterer

Effects of Different Materials on the Tribological Performance of PVD TiN Films under Starved Lubrication Regime

Grit blasting is one simple but effective method to modify the morphology of material surface and can improve the tribological performance. In this study, a thick TiN film was prepared by arc ion plating on the steel disk treated with grit blasting, and the rough surface coated solid film was obtained. The tribological properties of solid film against different materials were evaluated under starved lubrication regime. The results showed that the friction coefficients of rough titanium nitride (TiN) films were lower than those of rough steel disks exclude alumina ball under starved lubrication, and the wear rates of TiN film were negligible due to the high hardness of TiN film and small contact area. For four kinds of balls including steel ball, silicon nitride, zirconia, and alumina, the wear scar diameter of steel ball is biggest, and the wear scar diameters of other balls are small. The hardness of steel ball is less than others, which results in the easy abrasion and increases the contact area to reduce the pressure. So the friction coefficient of TiN against steel is low and steady

Analysis Of Nonlinear Graphene Plasmonics Using Surface Integral Equations

Graphene plasmonics have attracted significant attention in the past few years due to the remarkable optical and electrical properties of graphene. A highly effective method based on surface integral equations (SIE) in the frequency domain is proposed to describe both linear and nonlinear effects of graphene efficiently and accurately. Graphene, a centrosymmet-ric material, can possess second harmonic generation (SHG) when the conductivity is nonlocal. In this work, the fundamental harmonic (FH) of a graphene wrapped particle is studied as the first benchmark by introducing a conducting surface in SIE. Then it is modified to analyze a graphene-based patch antenna in both FH and SHG. This method can be extended to other two-dimensional materials easily, and fast multipole algorithm can be applied to accelerate the simulation