开关磁阻电动机的控制方式

介绍了开关磁阻电动机（ＳＲＭ）调速系统结构,论述了ＳＲＭ的两种速度控制方式－－单脉冲调角和脉宽调制,并对４相８／６极０．７５ｋＷ ＳＲＭ电机进行了控制实验,证实两种控制方式可行。     

开关磁阻电动机定子相电流新算法

根据开关磁阻电动机气隙磁导的变化情况来建立与ＳＲＭ相等效的同步电动机模型，应用派克方程业分析ＳＲＭ，用Ｚ变换和拉氏变换法来求ＳＲＭ的定子相绕组电流。提供了考虑磁路饱和影响时，ＳＲＭ定子相电流计算值的修正方法，并给出样机定相电流的计算值与实验结果，以利比较。     

开关磁阻电动机电流控制方式的研究

开关磁阻电动机（ＳＲＭ）的输出转矩与绕组电流波形有密切的关系，进行开关磁阻电机驱动系统（ＳＲＤ）的电机本体设计及功率变换器、控制器的设计，必须对绕组通电电流进行深入的研究。同时要使整个系统获得预定的转矩－转速特性，必须对电流进行合理的控制，本文在对开关磁阻电机驱动系统的运行特性进行分析的基础上，深入地研究了电机绕组电流控制方法，这无疑对ＳＲＤ系统的设计与控制有较大的意义。     

十二相高速异步发电机转子损耗

为了分析采用鼠笼实心转子特殊结构的十二相带整流负载高速异步发电机转子发热情况,需要准确求得电机转子中产生的损耗。采用有限元软件AN SY S对电机进行了二维谐波场及瞬态场的计算,将转子损耗分为定子基波电流产生的基波磁场引起的损耗、定子基波电流产生的齿谐波磁场引起的损耗和齿谐波磁导变化引起的损耗等3部分。仿真计算结果表明:基波磁场损耗较小,47、49次齿谐波磁场损耗较大,而齿谐波磁导变化引起的损耗最大。因此,在高速实心转子异步电机中,齿谐波磁场和齿谐波磁导变化在转子引起的损耗占转子损耗的主要部分。     

开关磁阻电机寻找初始位置的研究

开关磁阻电机(SRM)的转子必须与电机磁场保持同步才能保证电机的正常运行,因此对转子位置信息的准确检测非常重要。本小组通过向电机各相注入一定幅值的方波电压,利用相电流峰值及其与转子角位置之间的解析关系式求出转子的初始角位置,从而实现转子处于任何位置时的快速无反转起动。实验中,以一台四相8/6极SRM为对象进行相关实验,实验结果验证了该位置检测方法的可行性及预估相选取原则的正确性。     

开关磁阻电机快速非线性建模方法的研究

开关磁阻电机（ＳＲＭ）的双凸极结构使其电磁特性呈高度非线性，本文在对ＳＲＭ磁化特性曲线Ψ（θ，ｉ）深入分析的基础上，提出了一种新的建模方法，这种模型既具有较高的工程精度，又具有计算速度快的特性     

压水反应堆稳态自然循环载热能力的研究与分析

给出了压水反应堆稳态自然循环的物理与数学模型，并编制了用于分析，计算压水反应堆稳态自然循环载热能力及相相应参数间关系的程序ＭＩＳＡＲＳ。得用ＭＩＳＡＲＳ，计算了反应堆各参数对自然循环能力的影响，对计算结果作了分析。     

小功率SRD系统数学模型的建立与系统稳定性分析

本文根据ＳＲ电机状态方程及基尔霍夫电压电流定律推导出６／４极ＳＲ电机主电路数学模型，利用小信号拢动法给出ＳＲ电机电压斩波控制方式下的传递函数，并结合微机ＰＩＤ控制技术给出ＳＲＤ系统的传递函数，分析系统运行的稳定性，最后给出一个小功率ＳＲＤ系统控制实例。     

SMC爪极永磁电动机的设计特点

在简要分析开发软磁铁粉材料（ＳＭＣ）永磁电动机前景的基础上,设计并制造了一台以ＳＭＣ材料为铁心的爪极永磁同步电同,建立了电机的等值磁路图并进行了磁场分析,采用三维有限无数值方法进行了磁场计算,计算结果得到样机试验结果的验证,介绍了ＳＭＣ爪极永磁电动机样机的结构及设计特点。     

Tu－154飞机刹车盘骨架断裂特征及机理

采用ＸＲＤ，ＳＥＭ及ＳＴＥＭ探明了Ｔｕ－１５４客机刹车盘骨架疲劳断裂特征及机理。铁素体内含有大量位错，脆性相、氧化物及微孔洞，是材料形成穿晶断裂的基本原因。     

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

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