有损网络的宽带匹配理论

本文系统地发展了Youla的用于无损网络的宽带匹配理论,使之用于在微波集成电路中遇到的半均匀损耗网络。文中采用Andersen变换将S域的半均匀损耗网络变为λ域的虚拟无损网络,分析了在λ域的网络复数归一化散射矩阵,导出了此时负载传输零点对网络的限制条件,讨论了网络的可实现性并给出了此种有损宽带匹配网络的综合方法     

宽带匹配网络的机助综合——幅相实频技术(英文)

本文发表了宽带匹配网络的一种新的计算机辅助设计方法—幅相实频技术。勿需预先选定网络拓扑,按照通带内的极大—极小增益响应可直接确定匹配网络反射系数的幅值与相位响应。设定匹配网络的散射函数以逼近幅值与相位响应,即可综合匹配网络。设计的实践证明,此法所得结果优于目前采用的实频技术法。     

宽带对称五端口网络与一个定向耦合器构成的六端口网络分析仪

本文设计制作了一种微带型宽带、匹配、对称互易的五端口网络,这种电路结构简单、体积小,加工容易、频带宽,把它用于六端口网络分析仪,测试结果令人满意     

微波多级FET宽带放大器的实频直接设计法

给出多级级联网络的功率传输增益表达式。以该表达式为基础,提出微波多级FET宽带放大器的实频直接设计法。这一方法无需负载及FET的数学模型,只需知道其实频参数(阻抗或散射参数)即可。适当选择匹配网络的拓扑结构,即可进行优化设计,物理概念清晰,应用简便。宽带匹配网络可以计及集总元件的频率依变损耗,从而有利于提高微波宽带放大器的设计精度。     

宽带匹配网络设计的一种新方法—简化实频技术

本文在近年来国外出现的设计宽带匹配网络的实频技术的基础上,提出了一种简化实频技术。这一方法可按照通带内的极大——极小增益响应用最优化方法直接寻求匹配网络网络函数的实部。然后,利用Gewertz方法从实部求得完整的网络函数,据此以综合匹配网络。全部工作可由两个机助设计程序完成。文中给出了一个阻容并联负载匹配网络和一个微波单片集成电路FET放大器匹配网络的设计实例。     

一种宽带匹配网络的遗传算法设计

为同时兼顾带宽和效率,将遗传算法应用到天线宽带匹配网络设计中。遗传算法中建立了多目标优化目标函数即适应度函数。根据算法寻优结果,结合仿真软件仿真分析了所设计的宽带匹配网络的电特性。结果表明：该宽带匹配网络具有良好的阻抗宽带性能,证明了遗传算法在设计宽带匹配网络中的有效性。     

优化算法在宽带匹配网络中的应用

利用优化算法研究了宽带匹配网络,从设计过程可以看出,设计原理简单,使用方便,调试更灵活。其不仅能为所有的网络匹配问题（如天线的匹配、幅度均衡器等）的研究提供理论借鉴,而且能对宽带匹配网络的应用提供实践指导。     

C波段小型化宽带双圆极化微带阵列天线设计

设计实现了一种工作在C波段的2×2的宽带小型化双圆极化微带阵列天线.通过多层结构和支节匹配技术,拓展带宽;T型功分器顺序相差馈电形成馈电网络且左右旋馈电网络分层排布,实现小型化.实物测试结果表明,该天线VSWR2的阻抗带宽达39.5%,左旋和右旋3 dB轴比带宽均达到28.6%以上,在工作频带3.4～4.2 GHz内,左旋和右旋增益均在10 dB以上,天线阵列尺寸仅为1.27λ_0×1.27λ_0×0.1λ_0.实物测试结果与仿真结果吻合良好.     

考虑非高斯和宽带修正的桅杆风振疲劳分析

基于结构随机疲劳理论 ,给出了桅杆结构随机风振疲劳的分析方法 .在分析过程中考虑了桅杆结构在风荷载作用下响应的非高斯性以及宽带的影响 .得到了由非高斯性对桅杆疲劳引起的修正系数λ1和宽带因素引起的修正系数λ2 .最后 ,结合一个工程实例 ,给出了桅杆结构疲劳寿命计算的详细过程 .结果表明 ,与其他频域内的计算方法相比 ,该理论计算结构累积疲劳损伤的结果更加精确 .     

基于LMDS的小区宽带无线接入网方案设计

针对目前应用于住宅小区中的几种宽带接入技术的不足及为了解决因接入网宽带不足而出现的网络"瓶颈"问题,介绍了近年来受到国内外电信业务经营者普遍重视的一种新兴的宽带无线接入技术--LMDS.对基于LMDS技术的住宅小区宽带无线接入网络进行了设计.该系统可用频带宽,支持话音、数据、图象等双项通信业务,无须架设线路,具有建设速度快、初期投资小、系统扩展性好、受环境制约小、又能满足住宅用户对快速业务的需求.可以预见,LMDS将逐渐成为用于高速多媒体应用的最佳网络接入方案.     

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     

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     

Journal of Donghua University ( English Edition) Contents of Volume 31

正~~