Accurate EMC engineering on realistic platforms using an integral equation domain decomposition approach

This article investigates the efficiency, accuracy and versatility of a surface integral equation (SIE) multisolver scheme to address very complex and large-scale radiation problems including multiple scale features, in the context of realistic electromagnetic compatibility (EMC)/electromagnetic interference (EMI) studies. The tear-and-interconnect domain decomposition (DD) method is applied to properly decompose the problem into multiple subdomains attending to their material, geometrical, and scale properties, while different materials and arbitrarily shaped connections between them can be combined by using the so-called multiregion vector basis functions. The SIE-DD approach has been widely reported in the literature, mainly applied to scattering problems or small radiation problems. Complementarily, in this article, the focus is placed on realistic radiation problems, involving tens of antennas and sensors and including multiscale ingredients and multiple materials. Such kind of problems are very demanding in terms of both convergence and computational resources. Throughout two realistic case studies, the proposed SIE-DD approach is shown to be a powerful electromagnetic modeling tool to provide the accurate and fast solution which is indispensable to rigorously accomplish real-life EMC/EMI studies.Agencia Estatal de Investigación | Ref. TEC2017-85376-C2-1-RAgencia Estatal de Investigación | Ref. TEC2017-85376-C2-2-

Time Domain Inverse Scattering for a Buried Homogeneous Cylinder in a Slab Medium Using NU-SSGA

[[abstract]]A time-domain inverse scattering technique for reconstructing a buried homogeneous cylinder with arbitrary cross section in a slab medium is proposed. For the forward scattering, the FDTD method is employed to calculate the scattered E fields. Base on the scattering fields, these inverse scattering problems are transformed into optimization problems. The non-uniform steady state genetic algorithm (NU-SSGA) is applied to reconstruct the location shape and permittivity of the two-dimensional homogeneous dielectric cylinder. The NU-SSGA is a population-based optimization approach that aims to minimize the objective function between measurements and computer-simulated data. A set of representative numerical results is presented for demonstrating that the proposed approach is able to efficiently reconstruct the electromagnetic properties of homogeneous dielectric scatterer even when the initial guess is far away from the exact one. In addition, the effects of Gaussian noises on the image reconstruction are also investigated.[[notice]]補正完畢[[incitationindex]]SCI[[booktype]]電子

Research on Acceleration Technology for FDTD Based on Vivado HLS

时域有限差分法(Finitedifferencetimedomainmethod，FDTD)是一种电磁学计算的基本方法，通过空间内电场和磁场的交替计算，得到整个研究空间的电磁分布情况。对于很多电磁学问题，不论从概念上还是可实现性上来讲，时域有限差分方法都是最简单的计算方法。时域有限差分法可以解决复杂的电磁计算问题，但同时要消耗大量的计算机资源，并且花费较长的计算时间。为了更快速高效地得到计算结果，可以利用硬件技术进行加速，这也是近年来FDTD方法研究领域比较受关注的部分。Xilinx公司新推出的高级综合工具VivadoHLS(HighLevelSynthesis)，直接通过C/C++语言开发硬...In the field of computational electromagnetics, finite difference time domain method (FDTD) has been widely used. Using FDTD, the electromagnetic distribution of the whole field is obtained by alternating calculation of the electric and magnetic field. For many electromagnetical computational problems, FDTD is the simplest method, in consideration of conception and achievability. Although FDTD can...学位：工程硕士院系专业：物理科学与技术学院_工程硕士(电子与通信工程)学号：3432014115280

Microwave imaging of a partially immersed non-uniform conducting cylinder

[[abstract]]In this paper, we investigate the imaging problem to determine both the shape and the conductivity of a partially immersed non-uniform conducting cylinder from the knowledge of scattered far-field pattern of TM waves by solving the ill-posed nonlinear equation. Based on the boundary condition and the measured scattered field, a set of nonlinear integral equations is derived and the inverse problem is reformulated into an optimization one. The steady-state genetic algorithm is then employed to find out the global extreme solution of the object function. As a result, the shape and the conductivity of the conductor can be obtained. Numerical results are given to demonstrate that even in the presence of noise, good reconstruction can be obtained.[[notice]]補正完畢[[incitationindex]]SCI[[booktype]]電子

Finite-element-based generalized impedance boundary condition for modeling plasmonic nanostructures

The superior ability of plasmonic structures to manipulate light has propelled their extensive applications in nanophotonics techniques and devices. Computational electromagnetics plays a critical role in characterizing and optimizing the nanometallic structures. In this paper, a general numerical algorithm, which is different from the commonly used discrete dipole approximation, the finite-difference time-domain, and the surface integral equation (SIE) method, is proposed to model plasmonic nanostructures. In this algorithm, the generalized impedance boundary condition (GIBC) based on the finite element method (FEM) is formulated and converted to the SIE. The plasmonic nanostructures with arbitrary inhomogeneity and shapes are modeled by the FEM. Their complex electromagnetic interactions are accurately described by the SIE method. As a result, the near field of plasmonic nanostructures can be accurately calculated. The higher order basis functions, together with the multifrontal massively parallel sparse direct solver, are involved to provide a higher order accurate and fast solver. © 2011 IEEE.published_or_final_versio

ADVANCED IMPLEMENTATIONS OF THE ITERATIVE MULTI REGION TECHNIQUE

The integration of the finite-difference time-domain (FDTD) method into the iterative multi-region (IMR) technique, an iterative approach used to solve large-scale electromagnetic scattering and radiation problems, is presented in this dissertation. The idea of the IMR technique is to divide a large problem domain into smaller subregions, solve each subregion separately, and combine the solutions of subregions after introducing the effect of interaction to obtain solutions at multiple frequencies for the large domain. Solution of the subregions using the frequency domain solvers has been the preferred approach as such solutions using time domain solvers require computationally expensive bookkeeping of time signals between subregions. In this contribution we present an algorithm that makes it feasible to use the FDTD method, a time domain numerical technique, in the IMR technique to obtain solutions at a pre-specified number of frequencies in a single simulation. As a result, a considerable reduction in memory storage requirements and computation time is achieved. A hybrid method integrated into the IMR technique is also presented in this work. This hybrid method combines the desirable features of the method of moments (MoM) and the FDTD method to solve large-scale radiation problems more efficiently. The idea of this hybrid method based on the IMR technique is to divide an original problem domain into unconnected subregions and use the more appropriate method in each domain. The most prominent feature of this proposed method is to obtain solutions at multiple frequencies in a single IMR simulation by constructing time-limited waveforms. The performance of the proposed method is investigated numerically using different configurations composed of two, three, and four objects

Comparative Study of Some Population-based Optimization Algorithms on Inverse Scattering of a Two-Dimensional Perfectly Conducting Cylinder in Slab Medium

[[abstract]]The application of four techniques for the shape reconstruction of a 2-D metallic cylinder buried in dielectric slab medium by measured the cattered fields outside is studied in the paper. The finite-difference time-domain (FDTD) technique is employed for electromagnetic analyses for both the forward and inverse scattering problems, while the shape reconstruction problem is transformed into optimization one during the course of inverse scattering. Then, four techniques including asynchronous particle swarm optimization (APSO), PSO, dynamic differential evolution (DDE) and self-adaptive DDE (SADDE) are applied to reconstruct the location and shape of the 2-Dmetallic cylinder for comparative purposes. The statistical performances of these algorithms are compared. The results show that SADDE outperforms PSO, APSO and DDE in terms of the ability of exploring the optima. However, these results are considered to be indicative and do not generally apply to all optimization problems in electromagnetics.[[incitationindex]]SCI[[incitationindex]]EI[[booktype]]紙本[[booktype]]電子