- 标题
- 摘要
- 关键词
- 实验方案
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H-MATRIX ARITHMETIC FOR FAST DIRECT AND ITERATIVE METHOD OF MOMENT SOLUTION OF SURFACE-VOLUME-SURFACE EFIE FOR 3-D RADIATION PROBLEMS
摘要： Hierarchical (H-) matrix based fast direct and iterative algorithms are presented for acceleration of the Method of Moment (MoM) solution of the Surface-Volume-Surface Electric Field Integral Equation (SVS-EFIE) formulated for scattering and radiation problems on homogeneous dielectric objects. As the SVS-EFIE features the product of the integral operator mapping the tangential equivalent electric current on the surface of the scatterer to the volume polarization current and the integral operator mapping the volume polarization current to the tangential component of the scattered electric field, its MoM discretization produces the product of non-square matrices. Formation of the non-square H-matrices for the MoM discretized integral operators is described. The algorithms for arithmetics pertinent to the product of the non-square H-matrices are explained. The memory and CPU time complexity scaling of the required H-matrix operations are analyzed in details and verified numerically. The numerical validation of the proposed algorithm is provided for both the low-loss dielectric objects as well as for the high-loss biological tissues found in the bioelectromagnetics applications. The numerical experiments demonstrate a significant reduction of memory usage and a considerable speedup for CPU time compared to na?ve MoM, thus, enabling solution of the large-scale scattering and radiation problems with the SVS-EFIE.
关键词： computational electromagnetics,Method of Moments,SVS-EFIE,fast algorithms,bioelectromagnetics,H-matrix
更新于2025-09-23 15:22:29
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[IEEE 2019 Photonics & Electromagnetics Research Symposium - Fall (PIERS - Fall) - Xiamen, China (2019.12.17-2019.12.20)] 2019 Photonics & Electromagnetics Research Symposium - Fall (PIERS - Fall) - Fast Solution of Volume-surface Integral Equations for Conducting-anisotropic Media
摘要： Electromagnetic problems with both conducting and anisotropic media are formulated by volume-surface integral equations (VSIEs). The conducting medium is described by a surface integral equation while the anisotropic medium is governed by volume integral equations (VIEs) and they are coupled together via produced fields. The VSIEs are usually solved by the method of moments (MoM) in which the electric current density on the conductor surface is expanded by the Rao-Wilton-Glisson basis function while the volumetric flux densities inside the anisotropic medium are represented by the Schaubert-Wilton-Glisson basis function. In this work, we use a point-matching scheme to discretize the VIEs of dielectric part and couple it with the MoM for the conducting part. We also incorporate the hybrid scheme with the multilevel fast multipole algorithm to accelerate the solving process for electrically large problems. A numerical example is provided to illustrate the approach and good results have been obtained.
关键词： multilevel fast multipole algorithm,Volume-surface integral equations,method of moments,conducting-anisotropic media
更新于2025-09-23 15:21:01
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COMPUTATIONAL ASPECTS OF 2D-QUASI-PERIODIC-GREEN-FUNCTION COMPUTATIONS FOR SCATTERING BY DIELECTRIC OBJECTS VIA SURFACE INTEGRAL EQUATIONS
摘要： We describe a surface integral-equation (SIE) method suitable for computation of electromagnetic ?elds scattered by 2D-periodic high-permittivity and plasmonic scatterers. The method makes use of fast evaluation of the 2D-quasi-periodic Green function (2D-QPGF) and its gradient using a tabulation technique in combination with tri-linear interpolation. In particular we present a very e?cient technique to create the look-up tables for the 2D-QPGF and its gradient where we use to our advantage that it is very e?ective to simultaneously compute the QPGF and its gradient, and to simultaneously compute these values for the case in which the role of source and observation point are interchanged. We use the Ewald representation of the 2D-QPGF and its gradient to construct the tables with pre-computed values. Usually the expressions for the Ewald representation of the 2D-QPGF and its gradient are presented in terms of the complex complementary error function but here we give the expressions in terms of the Faddeeva function enabling e?cient use of the dedicated algorithms to compute the Faddeeva function. Expressions are given for both lossy and lossless medium parameters and it is shown that the expression for the lossless case can be evaluated twice as fast as the expression for the lossy case. Two case studies are presented to validate the proposed method and to show that the time required for computing the method of moments (MoM) integrals that require evaluation of the 2D-QPGF becomes comparable to the time required for computing the MoM integrals that require evaluation of the aperiodic Green function.
关键词： Faddeeva function,surface integral-equation (SIE) method,Ewald representation,method of moments (MoM),2D-quasi-periodic Green function (2D-QPGF)
更新于2025-09-23 15:19:57
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Nanoplasmonics - Fundamentals and Applications || Impedance Matching Analysis of Cylindrical Plasmonic Nanoantennas Fed by Optical Transmission Lines
摘要： An impedance matching analysis of two plasmonic nanocircuits connected to cylindrical nanoantennas is presented. In the first case, a bifilar optical transmission line (OTL) with finite length is connected between two nanodipoles, where one is illuminated by an optically focused Gaussian beam (receiving dipole) and the other radiates energy received from the OTL (emitting dipole). In the second case, the OTL is fed by a voltage source on one side and connected to a dipole‐loop composed antenna on the other side. These circuits are analysed electromagnetically by the linear method of moments (MoM) with equivalent surface impedance of conductors. Some results are compared using the finite element method. The results show the impedance matching characteristics of the circuits as a function of their geometries and the broadband response of the second circuit due the broadband dipole‐loop antenna.
关键词： broadband nanoantennas,cylindrical nanoantennas,method of moments (MoM),impedance matching,plasmonic circuits
更新于2025-09-19 17:13:59
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Lumen Degradation Lifetime Prediction for High Power White LEDs based on the Gamma Process Model
摘要： Nowadays, due to the advancement of design and manufacturing technology, there are many consumer products with high reliability. Similarly, the competition in the business sector influences the product development time to become shorter and that makes it difficult for manufacturers to evaluate the reliability of current products before new products are released to the market. This phenomenon is manifested in the lighting industry, especially for the high power white light-emitting diodes (LEDs) as these products have a long lifetime and high reliability. Currently, the standard to predict the lifetime of LEDs is based on a deterministic nonlinear least squares method which has low prediction accuracy. To overcome this, degradation models are being used to study the reliability of such products, considering the uncertainties and the quality characteristics whose degradation over a period of time can be related to the product lifetime. A stochastic approach based on gamma distributed degradation (GDD) is proposed in this study to estimate the long-term lumen degradation lifetime of phosphor-converted white LEDs. An accelerated thermal degradation test was designed to gather luminous flux degradation data which was analyzed based on maximum likelihood estimation (MLE) and the method of moments (MM) to estimate the parameters for the GDD model. The MLE method has shown superiority over MM in terms of the estimation of the model parameters due to its iterative algorithm being likely to find the optimal estimation. The lifetime prediction results show that the accuracy of the proposed method is much better than the TM-21 nonlinear least squares (NLS) approach which makes it promising for future industrial applications.
关键词： Luminous flux degradation,Gamma distributed degradation (GDD),Method of moments,Light-emitting diodes (LEDs),Maximum likelihood estimation
更新于2025-09-16 10:30:52
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Plasmonic Nano-antenna Optimization Using Characteristic Mode Analysis
摘要： Plasmonic nano-antennas are typically designed with RF-inspired rigorous parametric optimization processes that lack proper physical insights. In this study, we demonstrate a systematic optimization approach for nano-antennas based on characteristic mode analysis (CMA). A complex geometry, designated as split-ring two-wire antenna (SRA), is selected and optimized using the CMA technique. CMA identifies the dominant modes of the structure at the frequency of interest as well as explains the dependency of the modes on the structure’s shape, size and material properties. These insights from CMA have been used in the present study to efficiently optimize SRA shape, size, and material which yield more than 700 % near-field intensity enhancement (NFIE) at the desired operating frequency. This proposed CMA based optimization method can be adapted easily for many other nano-antenna applications, facilitating the development of improved nano-structures.
关键词： Split-ring Two-wire Antenna (SRA),Method of Moments (MOM),Plasmonic,Nano-structures / Nano-antennas,Near Field Intensity Enhancement (NFIE),Surface Integral Equation (SIE),Characteristic Mode Analysis (CMA)
更新于2025-09-11 14:15:04
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[IEEE 2018 XXIIIrd International Seminar/Workshop on Direct and Inverse Problems of Electromagnetic and Acoustic Wave Theory (DIPED) - Tbilisi, Georgia (2018.9.24-2018.9.27)] 2018 XXIIIrd International Seminar/Workshop on Direct and Inverse Problems of Electromagnetic and Acoustic Wave Theory (DIPED) - MoM Solution to Scattering Problem on Multi-Region Composite Structures with Various Type Material Junctions
摘要： This paper develops a MoM-based full-wave solution to the scattering problem on arbitrary multi-region composite structure with various type junctions between dielectric and conducting regions. A special attention is paid to the treatment of basis functions (BF) on material junctions. In contrast to existing works, the standard RWG BF are supposed to be used and grouped according to the boundary conditions on contiguous interfaces. The proposed approach has been validated by comparison of the simulated results with those obtained by discontinuous Galerkin time domain (DGTD) method.
关键词： Basis functions,method of moments (MoM),material junctions,numerical simulations,composite structures
更新于2025-09-11 14:15:04
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Backscattering from Fractal Rough Surfaces Under Tapered Wave Illumination
摘要： In this paper, a method of Numerical Maxwell Model in 3D Simulations (NMM3D) is used to evaluate the backscattering information of fractal rough surfaces. Weierstrass Mandelbrot function is employed to generate natural rough surfaces. Quantitative analyses are demonstrated on the relation of fractal parameters and rough surface parameters. In order to eliminate the unwanted edge effects, a tapered incident wave model is built to illuminate the surface models with the use of sampling strategy. Method of Moments is employed to evaluate the backscattered fields. The results are demonstrated and show a good agreement with AIEM model.
关键词： Tapered wave,Backscattering coefficient,Fractal surface,NMM3D,Method of Moments
更新于2025-09-10 09:29:36
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[IEEE 2018 International Conference on Electromagnetics in Advanced Applications (ICEAA) - Cartagena des Indias, Colombia (2018.9.10-2018.9.14)] 2018 International Conference on Electromagnetics in Advanced Applications (ICEAA) - Accelerating the Domain Green’s Function Method with the Equivalent Dipole-Moment technique
摘要： The domain green’s function method (DGFM) [1] and its enhancement through the iterative Jacobi approach is a novel method-of-moments (MoM) based domain decomposition technique that can be used to analyse ?nite antenna arrays consisting of identical, disconnected elements. Fundamental to the DGFM is the calculation of the active impedance matrix for each array element. This matrix is formulated as a weighted summation of the self-interaction matrix for the array element, to which the coupling sub-matrices are added that account for the surrounding array environment. When considering the computational complexity of the algorithm, this step in the solution process dominates the runtime. Previously, the adaptive cross approximation (ACA) was used to obtain a low-rank approximation for the coupling terms that signi?cantly accelerated this summation [2]. In this work, an alternative approach is proposed to accelerate this calculation based on representing the reaction between two separated basis functions with the equivalent dipole-moment (EDM) method [3], [4].
关键词： method-of-moments,domain decomposition,?nite array analysis
更新于2025-09-10 09:29:36
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Application of the Method of Moments for Calculating Electrodynamic Characteristics of a Quasistatic Antenna in an Anisotropic Medium
摘要： We develop the numerical method of moments for solving an integral equation that describes the distribution of the charge along a thin finite-length antenna wire in an anisotropic medium in the quasistatic approximation. It is shown that the method of moments can be used to calculate the electrodynamic characteristics of such an antenna under the conditions where the kernel of the integral equation has a singularity related to the resonance cone. The influence of the ratio between the elements of the dielectric permittivity tensor and the method of partitioning of the antenna surface on the calculation accuracy is analyzed. It is shown that the relative error of calculations of the antenna characteristics is a fairly small value of about 1 % if the antenna wire is divided into ten segments.
关键词： electrodynamic characteristics,anisotropic medium,resonance cone,method of moments,quasistatic antenna
更新于2025-09-10 09:29:36