等离子环境中带电体能量的Collin变分

基于系统性电磁兼容的考虑,对等离子环境中在轨航天器导体充放电现象中的能量特征进行了变分研究.通过电磁Collin原理,对等离子环境中导体系统几何尺度与所带电能的变分联系进行了理论分析.在此基础上,推广了更具一般性的数值估值分析方法,并对复杂导体系统电磁参数、等离子环境特征与系统能量间的关系进行了实例分析.研究结果对于等离子环境中复杂带电体的能量控制及相关的电磁环境效应与防护等研究具有积极意义.     

“复杂电磁环境技术”专辑组稿通知

<正>经与第三届全国复杂电磁环境技术及应用学术会议会务组商定,《强激光与粒子束》编辑部邀请汪连栋研究员作为客座主编,策划组织出版一期《强激光与粒子束》"复杂电磁环境技术"专辑(正刊),优选发表本次会议的论文投稿。1征文主题(不限于以下主题)空间装备静电充放电规律与防护方法宽带强电磁脉冲场模拟技术新技术复杂电磁环境基础理论复杂电磁环境数值仿真技术武器装备复杂电磁环境效应机理研究雷电防护理论与技术射频前端电磁防护新原理     

JEMS-FDTD软件在运输机电磁特性仿真中的应用

复杂电磁环境的研究包括多方面内容,其中飞行器的电磁环境效应研究受到了较多的关注。随着计算机技术的飞速发展,利用数值模拟技术获得飞行器电磁特性已经成为飞行器电磁环境效应研究的一个重要手段。我们将自主研发的大规模并行三维时域全波电磁模拟软件JEMS-FDTD应用于运输机整机电磁特性仿真,计算并分析了飞机的电磁耦合散射特性,获得了飞行器在电磁脉冲照射下的时域/频域、近场/远场等电磁信息。计算中为保证精度采用了非均匀以及高阶FDTD计算技术。     

超短波跳频电台复杂电磁环境适应能力评估方法

以某型超短波通信电台为例,分析了该电台工作于跳频组网状态时所面临的复杂电磁信号环境,在电台使用区域内,根据构成威胁电磁环境、目标电磁环境和背景电磁环境的各电子设备的频谱占用度、时间占有度、空间覆盖率的不同,提出了复杂电磁环境量化分级标准。采取实装构设与模拟仿真技术相结合的手段,分别构建了针对该电台的简单、轻度、中度和重度等不同级别的复杂电磁环境,并给出了电台对不同等级复杂电磁环境适应能力的初步评估结论。项目成果可为今后电子信息装备复杂电磁环境适应性的理论研究工作提供有益借鉴。     

第三届全国复杂电磁环境技术及应用学术会议第一轮征文通知

正为加强我国复杂电磁环境研究领域学术交流,拓展科研人员研究视野,活跃学术氛围,推动我国复杂电磁环境及相关技术的发展,拟定于2019年4月中旬举办第三届全国复杂电磁环境技术及应用学术会议,特邀请贵单位积极组织参与,踊跃投稿。现将有关征文事项通知如下。     

无人机在复杂电磁环境下的效能评估

通过分析无人机的结构层次和研究复杂电磁环境对无人机的影响,建立了复杂电磁环境下无人机的效能评估指标体系,通过主观赋权法和客观赋权法得到各项指标的权重,针对评估指标的模糊性和不确定性,基于云理论的原理,实现一定条件下评估指标的定性与定量的描述,综合考虑了评估过程中的模糊性和不确定性因素,并利用评价云模型拟合出无人机在复杂电磁环境下的综合效能。结合实例模拟分析表明,复杂电磁环境下的无人机云效能评估模型,为复杂电磁环境下无人机的定量化效能评估提供参考。     

无人机在复杂电磁环境下的效能评估

通过分析无人机的结构层次和研究复杂电磁环境对无人机的影响,建立了复杂电磁环境下无人机的效能评估指标体系,通过主观赋权法和客观赋权法得到各项指标的权重,针对评估指标的模糊性和不确定性,基于云理论的原理,实现一定条件下评估指标的定性与定量的描述,综合考虑了评估过程中的模糊性和不确定性因素,并利用评价云模型拟合出无人机在复杂电磁环境下的综合效能。结合实例模拟分析表明,复杂电磁环境下的无人机云效能评估模型,为复杂电磁环境下无人机的定量化效能评估提供参考。     

第三届全国复杂电磁环境技术及应用学术会议第一轮征文通知

<正>为加强我国复杂电磁环境研究领域学术交流,拓展科研人员研究视野,活跃学术氛围,推动我国复杂电磁环境及相关技术的发展,拟定于2019年4月中旬举办第三届全国复杂电磁环境技术及应用学术会议,特邀请贵单位积极组织参与,踊跃投稿。现将有关征文事项通知如下。     

第三届全国复杂电磁环境技术及应用学术会议第一轮征文通知

<正>为加强我国复杂电磁环境研究领域学术交流,拓展科研人员研究视野,活跃学术氛围,推动我国复杂电磁环境及相关技术的发展,拟定于2019年4月中旬举办第三届全国复杂电磁环境技术及应用学术会议,特邀请贵单位积极组织参与,踊跃投稿。现将有关征文事项通知如下。     

第三届全国复杂电磁环境技术及应用学术会议第一轮征文通知

<正>为加强我国复杂电磁环境研究领域学术交流,拓展科研人员研究视野,活跃学术氛围,推动我国复杂电磁环境及相关技术的发展,拟定于2019年4月中旬举办第三届全国复杂电磁环境技术及应用学术会议,特邀请贵单位积极组织参与,踊跃投稿。现将有关征文事项通知如下。一、时间和地点时间:2019年4月中旬地点:河南·洛阳二、主办单位中国兵工学会复杂辐射场技术及应用专业委员会电子信息系统复杂电磁环境效应国家重点实验室     

计算电磁学研究中的V&V方法概述

随着数值模拟在电磁学研究中发挥的作用越来越大,验证与确认技术也越来越得到研究者的重视。介绍了验证与确认(VV)技术的基本概念、发展简况、具体研究对象和研究方法。总结和概括了目前国内外在电磁场计算中已经开展的VV研究工作,介绍了IEEE制定的计算电磁学建模与模拟确认标准。介绍了本单位目前在程序验证、物理模型误差分析、计算模型参数提取等方面开展的VV工作,讨论了VV研究在计算电磁学中发挥的作用及可能的研究方向。     

计算电磁学研究中的V&V方法概述

随着数值模拟在电磁学研究中发挥的作用越来越大,验证与确认技术也越来越得到研究者的重视。介绍了验证与确认(VV)技术的基本概念、发展简况、具体研究对象和研究方法。总结和概括了目前国内外在电磁场计算中已经开展的VV研究工作,介绍了IEEE制定的计算电磁学建模与模拟确认标准。介绍了本单位目前在程序验证、物理模型误差分析、计算模型参数提取等方面开展的VV工作,讨论了VV研究在计算电磁学中发挥的作用及可能的研究方向。     

Bandwidth evaluation of dispersive transformation electromagnetics based devices

In this paper, the transient responses of some devices which are based on transformation electromagnetics are studied, such as invisible cloaks and concentrators, by using the Finite-Difference Time-Domain (FDTD) numerical technique. In particular, effects of the inherent losses as well as the coating size of the ideal cylindrical cloak on its bandwidth and cloaking performance are examined. In addition, it is demonstrated that the performance of transformation electromagnetics based devices is affected by the material parameters in the design, although they may behave nicely under monochromatic plane wave illuminations. The obtained results are of interest for the future practical implementation of these structures.     

Numerical modeling of urban sound fields by a diffusion process

In this paper, we present the numerical implementation of a sound field model used in urban acoustics. The mathematical model being based on a classic diffusion equation for the sound energy, a simple finite difference scheme is applied. We give also some finite difference equations for simple boundary conditions, like absorption by a wall and at building edges. The two-dimensional numerical scheme is then compared to analytical solutions of the sound field propagation in a rectangular street with a good agreement, both in the steady state and in the time varying state. Finally it is suggested that the adjustment of usual softwares for heat transfer could be an interesting and low cost way to develop powerful acoustic softwares for the prediction of noise in urban areas.     

电磁波导的辛分析与对偶棱边元

将电磁波导的控制方程导向了Hamilton体系、辛几何的形式.以电磁场的横向分量组成对偶向量并采用分离变量法，可以得到Hamilton算子矩阵的辛本征值问题.共轭辛正交归一关系、辛本征解展开定理等均可在此应用.对于复杂横截面和填充非均匀材料的电磁波导，提出对偶棱边元，对截面半解析离散后即可进行数值求解.对偶棱边元克服了结点基有限元求解电磁场问题的困难，与常规棱边元相比在某些方面具有一定的优势. 关键词： 电磁波导 Hamilton体系 对偶变量 棱边元     

Resistivity, Heating and Radial Transport on the Axis of the Tokamak Discharge

In this work we present analytical and numerical results on the resistivity, heating and radial transport of particles momentum and heat on and near the minor axis of the Tokamak discharge. The crucial role of impurities is emphasized. Asymptotically exact electromagnetics and classical fluid dynamics are utilized to obtain first the case of the straight infinite cylinder. Toroidal effects are then included at the level of the Pfirsch-Schlüter theory. Analytical results from the complete model show the transport coefficients to be classical with enhanced values related to the presence of the impurity ions and the toroidal effects. Numerical results from a simpler simulation model are found to be in reasonable agreement with published experimental results from the ST-Tokamak.     

Preconditioning based on Calderon’s formulae for periodic fast multipole methods for Helmholtz’ equation

Solution of periodic boundary value problems is of interest in various branches of science and engineering such as optics, electromagnetics and mechanics. In our previous studies we have developed a periodic fast multipole method (FMM) as a fast solver of wave problems in periodic domains. It has been found, however, that the convergence of the iterative solvers for linear equations slows down when the solutions show anomalies related to the periodicity of the problems. In this paper, we propose preconditioning schemes based on Calderon’s formulae to accelerate convergence of iterative solvers in the periodic FMM for Helmholtz’ equations. The proposed preconditioners can be implemented more easily than conventional ones. We present several numerical examples to test the performance of the proposed preconditioners. We show that the effectiveness of these preconditioners is definite even near anomalies.     

Unified boundary integral equation for the scattering of elastic and acoustic waves: solution by the method of moments

A unified boundary integral equation (BIE) is developed for the scattering of elastic and acoustic waves. Traditionally, the elastic and acoustic wave problems are solved separately with different BIEs. The elastic wave case is represented in a vector BIE with the traction and displacement vectors as unknowns whereas the acoustic wave case is governed by a scalar BIE with velocity potential or pressure as unknowns. Although these two waves can be unified in the form of a partial differential equation, the unified form in its BIE counterpart has not been reported. In this work, we derive the unified BIE for these two waves and then show that the acoustic wave case can be derived from this BIE by introducing a shielding loss for small shear modulus approximation; hence only one code needs to be maintained for both elastic and acoustic wave scattering. We also derive the asymptotic Green's tensor for zero shear modulus and solve the corresponding vector equation. We employ the method of moments, which has been widely used in electromagnetics, as a numerical tool to solve the BIEs involved. Our numerical experiments show that it can also be used robustly in elastodynamics and acoustics.     

大力开展我国电磁兼容技术的科研工作及若干建议

：本文介绍了国际上关于环境电磁学及电磁兼容技术的一些科研进展情况,描述了电磁兼容的动态,最后并提出了若干建议.     

Numerical Analysis of Electromagnetic Fields in Multiscale Model

Modeling technique for electromagnetic fields excited by antennas is an important topic in computational electromagnetics, which is concerned with the numerical solution of Maxwell's equations. In this paper, a novel hybrid technique that combines method of moments(MoM) with finite-difference time-domain(FDTD) method is presented to handle the problem. This approach employed Huygen's principle to realize the hybridization of the two classical numerical algorithms. For wideband electromagnetic data, the interpolation scheme is used in the MoM based on the dyadic Green's function. On the other hand, with the help of equivalence principle, the scattered electric and magnetic fields on the Huygen's surface calculated by MoM are taken as the sources for FDTD. Therefore, the electromagnetic fields in the environment can be obtained by employing finite-difference time-domain method. Finally, numerical results show the validity of the proposed technique by analyzing two canonical samples.