GMRES方法在分析三维介质目标电磁散射问题中的应用

把广义最小余数法(GMRES)和矩量法(MOM)结合起来研究三维介质目标的电磁散射问题。对三维介质目标的远区散射场进行了计算,结果与高斯消去法和共轭梯度法(CGM)的计算结果进行了比较,它们吻合的很好,而GMRES方法的计算效率大大提高,说明GMRES方法和MOM的结合是求解三维电磁散射问题的有效途径之一。     

三面角反射器多次散射图形电磁计算(英文)

利用物理光学 (PO)求解三面角反射器 (TCR)的多次散射场 ,计算结果突出表明了三面角反射器的多次散射贡献。同时利用图形电磁计算 (GRECO)来实现可视化实时计算 ,计算结果令人满意 ,具有重要的工程应用价值。     

基于矩量法的三维导体目标散射问题的研究

将CAD(computer aided design)建模与矩量法相结合并应用于三维导体目标散射问题的研究.在CAD建模的基础上,得到了符合电磁计算要求的几何数据,并以此为基础计算得到表面电流,散射场等电磁参数.分析了非奇异积分的数值解及奇异积分的解析解,指出了奇异积分出现的具体条件,给出了几种典型三维导体结构的雷达反射截面(radar cross section,RCS),平面天线输入阻抗与经典理论计算进行了比较.仿真结果表明,CAD建模与矩量法相结合的算法对于计算三维导体散射场,RCS等相关电磁特性具有广泛的适用性及准确性.     

计算三维电磁散射的矢量场表面辐射条件算子

本文利用矢量场的辐射边界条件(Radiation Boundary Condition,简称RBC)推导出矢量场的一阶辐射条件算子,并介绍了该算子在三维电磁散射计算中的应用。文中应用该算子在散射体表面的性质,近似计算了理想导电圆球的表面感应电流分布和雷达散射面积。数值计算结果与级数展开解一致性较好。     

复杂目标RCS可视化电磁计算方法的改进

复杂目标的电磁散射主要来源于面元及棱边,在照明区与阴影区交界处,相位出现快速变化,给图形电磁计算带来计算误差。棱边散射场计算中,单站增量长度绕射系数较简单,计算精度低。文章在不改变反射系数情况下,使用驻相法消除奇变效应。提出将等效电流绕射系数、物理光学绕射系数及并矢绕射系数,应用于棱边散射场图形电磁计算。从而提高了RCS计算精度。该方法对我国的隐身与反隐身技术及仿真技术的研究,具有重要的实用价值。     

各向异性曲面结构图形电磁计算

利用物理光学来分析各向异性曲面的散射场, 数值计算结果将突出显示各向异性材料产生的影响. 同时利用图形电磁计算(GRECO)方法实现对各向异性材料的曲面结构的电磁计算. 结果表明, 该方法是正确有效的, 具有重要的工程应用价值.     

复杂涂敷目标的RCS计算

给出了一种快速计算复杂涂敷目标散射场的方法。将复杂目标电磁散射分成面元和边缘散射,运用物理光学(PO)、阻抗边界条件(IBC)、等效电流(EM C)和物理绕射理论(PTD)对复杂目标雷达散射截面(RCS)进行计算,并将计算结果与文献结果及无涂敷纯金属目标的RCS进行对比分析,结果与文献及预期估计情况吻合较好,表明该方法不仅计算简单,而且结果也较为精确。     

一种直接计算目标双站RCS的图形电磁计算方法

提出了一种结合图形电磁计算直接计算目标双站RCS的新方法。通过读取物体表面相对于入射方向和相对于散射方向的深度值,完成了对能产生散射场和绕射场的面和棱边的识别;修正了几何绕射场存在物理光学重复计算的问题,引入了物理绕射系数和等效电磁流相结合的方法。实例表明本文方法计算结果与文献结果吻合,从而证明本文方法的有效性。     

飞机基本构件电磁散射的FD-TD方法

采用电磁工作者广为关注的FD—TD方法，对飞机的基本构成部件(方柱、圆柱、平板)的电磁散射问题，进行了研究。采用矩形网格及合适的吸收边界与连接边界，导出了基本部件某一封闭面上散射场的FD—TD计算公式；采用频域Love等效原理，实现了近场—远场变换，大大减少了计算量，所得散射截面(RCS)与实测或其它方法计算结果相比，吻合较好。本方法与高频近似方法——GTD相比，避免了多径绕射及高次绕射的射线寻迹困难，与频域方法相比，它可解决超宽带电磁散射预测问题。     

等离子体电磁散射的多物理场研究

本文采用有限元方法对等离子体的电磁散射问题进行了多物理场分析。分析了温度场分布与电子密度分布的关系。在得到电子密度分布后,利用Drude模型得到了介电常数的空间分布。随后对圆柱的电磁散射特性进行了分析计算,给出了雷达双站散射截面的计算结果,并对结果进行了分析比较。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with