微波,电磁场工程计算软件及方法发展概况

本文较为详细地讨论了微波、电磁场工程数值模拟技术的现状及应用前景，叙述了电磁场数值模拟过程，对各种常用计算方法进行了比较。     

电磁场时域数值方法及其混合技术概述

时域数值方法是计算电磁学领域的研究热点和常用方法。本文对多种典型电磁场时域数值方法的原理和特点加以简要评述;总结了涉及该类方法的混合技术,主要是信号处理技术在时域数值方法中的应用;最后对该方法的发展前景作了展望。     

基于MATLAB的电磁场数值分析

本文介绍了电磁场的数值计算方法以及如何应用MATLAB来实现.通过具体实例,介绍了有限差分法和有限单元法在二维静态电磁场边值问题数值求解中的优越性.     

并行时域平面波在电大目标瞬态散射中的应用

基于电磁场时域积分方程数值技术计算复杂目标的瞬态散射特性,其计算量和内存需求大,应用经典的单元分组算法-时域平面波算法,降低了时域积分方程的计算规模.文中在研究时域平面波算法并行算法的基础上,开发了基于.NET Remoting 的电磁场分布式数值计算方案.数值结果表明,该分布式并行方案显著提高了时域平面波算法的计算效率,为解决电大目标瞬态电磁散射问题提供了一条有效途径.     

利用带限信号的部分时域信息和频域信息恢复信号

本文在介绍带限信号恢复问题及有关算法的基础上，从理论上详细讨论了一类的带限信号的恢复问题，即在只知道时域的部分值和频域的部分值而不知道频带的情况下，给出了相应的算法，并论证了算法的收敛性及算法收敛的只一性，而且对外推的数值计算误差及外推和稳定性也作了说明。本文还给出了模拟例子以及数字仿真的结果。本文提出了的算法是行之有效的。     

基于Matlab的电场有限元数值计算分析

有限元法是对电磁场进行数值求解的重要方法,也是本科电磁场课程的教学内容之一.论文结合本科教材阐述了对电场进行有限元计算时的数学模型和算法原理,介绍了Matlab软件基本的矩阵处理编程方式和电场场域有限元分析的算法框图.进而联系教材中一个电器的电场电位分布计算实例,在Matlab环境下进行有限元计算编程的实现.数值解与解析解的比较结果表明Matlab应用在对电磁场进行有限元计算所具备的合理性与简易性.本文对本科教学中帮助学生理解电磁场的数值计算及其编程实现有一定的参考意义.     

基于内插与外推的数字全息分辨率增强方法

为了提高数字全息再现图像的分辨率,分析了增强图像分辨率的典型方法,提出了同时采用图像内插与外推的数字全息分辨率改进方法。对采集的全息图运用图像算法进行向内插值与向外填充,在全息面和物面之间采用角谱方法进行双向衍射迭代。通过该方法可以实现全息图的内插与外推,内插过程可以增加全息图空间采样频率而外推过程扩大了全息图数值孔径。同时,讨论了内插与外推的限制因素,并将新的改进方法与单独采用外推或内插进行了比较,模拟和实验结果证明,运用该方法可以明显改善再现图像分辨质量。     

灰度／深度图像序列的三维空间插—一种新的计算机图像生成技术

本文提出的灰度／深度图像序列的三维内插方法，摆脱了原实摄路径限制，可在空间内任意巡行，采用空间稀疏化采样，从而达到大量节省存储量和高度灵活地可控再现空间场景的目的。为解决三维内插中庞大的计算量，我们研究了快速而实用的散点算法和深度适应的Ｗａｒｐ算法。通过介绍三维内插的几种简单情形，导出了一些简单、实用的算法。计算机仿真结果显示了这一新方法是完全可行的。     

电磁理论中复超越方程的数值解法研究

简要介绍Ｋｕｈｎ法，并以多个数值计算实例研究如何应用Ｋｕｈｎ法来解决电磁场与微波领域中遇到的复超越方程的数值求解问题。     

电磁场数值模拟TLM算法及其应用

传输线矩阵（TLM）算法是基于Huygens的波传播模型，与计算机结合起来后，成为一种强有力的三维时域电磁场数值仿真算法，在1971年TLM被首次提出以后，便得到不断的改进，从二维到三维，从扩展型结点到凝缩型结点，从时域TLM到频域TLM，而其应用也从最初的处理电磁场问题发展到对微波电路的模拟，高速IC的设计，以及处理光学，机械学，热学和声学问题，本文详细介绍了二维、三维空间的TLM算法，扩展型结点和几种改进的对称凝缩结点，阐述了TLM在各领域的应用，最后还简单介绍了我们完成的工作。     

Comparison of interpolation and extrapolation methods with a method using multiresolution wavelet transform in dosimetric experiments

International and national organizations have recommended limits for the protection of mobile phone users and standards are going to be established to certify the compliance of mobile phone with these limits. To ensure this conformity, numerical and experimental dosimetric analyses are essential to evaluate the electric field in the user’s head. The use of interpolation and extrapolation is then necessary to evaluate the electric fields components which cannot be measured. In this paper, an interpolation/extrapolation method using wavelets is presented. This method is applied to one, two, and three-dimensional sampled data from dosimetric experiments and compared with other interpolation/extrapolation techniques.     

A 3-D Radial Point Interpolation Method for Meshless Time-Domain Modeling

In this paper, the radial point interpolation method, one of the meshless numerical techniques that has recently emerged in the area of computational electromagnetics, is extended to three dimensions for time-domain electromagnetic modeling. Its capabilities of conformal and multiscale modeling of arbitrary geometries over conventional grid-based numerical techniques are numerically validated and evaluated. A general approach to determining the numerical stability condition of the method is described. Consequently, this study presents another possible approach to automatic meshing of complex structures and an adaptive scheme for numerical solution refinements.      

Methodology to interpolate and extrapolate SAR measurements in avolume in dosimetric experiment

There has been an explosive growth in the area of wireless communication. Over the world, hundreds of millions of subscribers are using mobile phones. International and national organizations have recommended limits for the protection of mobile phone users and standards are going to be established to certify the compliance of mobile phones with these limits. To ensure this conformity, numerical and experimental dosimetric analyzes are essential to evaluate the electric fields inside the user's head. These fields can not be measured near the mobile phone- the phantom interferes where they are a maximum and the use of interpolation and extrapolation is then necessary to evaluate the electric field components. This paper describes the interpolation and extrapolation methodologies, of the experimental sampled data in three dimensions, of the power absorbed in the whole volume of the head phantom. A new method to interpolate and extrapolate SAR measurements is presented. This technique, which is very fast and not very expensive in terms of required memory, is compared with other interpolation techniques which use splines or wavelets     

Fast MM-PO-based numerical modelling technique for wideband analysis of antennas near conducting objects

A highly efficient computational electromagnetics technique based upon method of moments-physical optics (MM-PO) hybrid formulation combined with the impedance matrix interpolation and a dynamic adaptive frequency sampling for wideband analysis of antennas radiating in the presence of conducting bodies is presented. Sample numerical results demonstrate the capability of the technique     

基于理论弹道速度匹配的飞行器测控记忆跟踪算法

针对遥测设备现有记忆跟踪存在速度跳变和外推误差大的问题,提出了一种基于理论弹道速度匹配的记忆跟踪算法。分析了遥测设备记忆跟踪算法原理与不足,对原记忆跟踪算法进行改进,同时将Neville算法用于记忆跟踪数据插值。仿真结果表明新算法外推10 s、5 s和3 s的均方根误差比原算法平均减小44.9％。新算法在设备应用的测试结果同样证明了其优越性。     

A general framework for developing and evaluating band-limitedfunction extrapolation methods

It is shown that the bandlimited function extrapolation can be considered as an approximation problem in operator space. Within this framework, the Papoulis-Gerchberg method and two other methods for extrapolation are analyzed. Particular attention is given to approximation using Taylor and Chebyschev series, and to approximation using the Lagrange interpolation method     

有耗介质柱体瞬态散射积分方程的新解法

本文研究二维非均匀有耗介质柱在电极化二维脉冲波激励下的瞬态散射。采用分片双线性插值的空间离散方案,经解析处理,子域上的积分能得到闭式结果。离散化方程在复频域用CG-FFT法求解,并用一种新外推法产生初值,数值结果证实了本文方法的有效性。     

Efficient radar signature prediction using a frequency-aspectinterpolation technique based on adaptive feature extraction

A radar cross section (RCS) interpolation technique in both frequency and aspect is proposed for the efficient prediction of radar signatures from computational electromagnetics data. Our approach is based on a multiple-arrival model for the induced current on the target. The model parameters are determined by an adaptive feature extraction (AFE) algorithm, which uses an iterative search-and-extract procedure to find the individual model features. Random frequency and aspect sampling is used to circumvent the ambiguity in selecting the features. Numerical examples are presented to test the interpolation algorithm. It is found that sufficient accuracy in the predicted radar features can be achieved even when the original computed data is sampled at 5:1 below the Nyquist criterion in either frequency or aspect. The algorithm is also applied to efficiently predict the radar images of the benchmark VFY218 airplane at UHF band with good results     

Extrapolation and spectral estimation with iterative weighted normmodification

An algorithm is developed to define, from the data samples themselves, a frequency-weighted norm to use in minimum-weighted-norm extrapolation. The iterative procedure developed consists of using a periodogram spectrum estimate obtained from some samples of the signal estimate/extrapolation found at one iteration to define the weight that is used to estimate at the next iteration. This algorithm usually converges in less than 10 iterations to an extrapolation which is characterized as a nonparametric frequency-stationary extension of the data. The frequency resolution and extrapolation length are controlled by the length of a time-domain window used to obtain smooth spectral estimates between iterations. Examples are provided to illustrate the use of the algorithm for interpolation/extrapolation. The examples give comparable results to nonadaptive extrapolation methods without the need for a priori knowledge. For a certain spectral estimation example, the algorithm provides comparable resolution to the parametric methods with more accurate values of the relative strengths of the narrowband components     

Genetic algorithm optimization applied to electromagnetics: areview

Genetic algorithms are on the rise in electromagnetics as design tools and problem solvers because of their versatility and ability to optimize in complex multimodal search spaces. This paper describes the basic genetic algorithm and recounts its history in the electromagnetics literature. Also, the application of advanced genetic operators to the field of electromagnetics is described, and design results are presented for a number of different applications