SRD的PWM调压调速

根据开关磁阻电动机调速系统 ( SRD)的 PWM调压调速理论 ,论述了采用集成电路TL494实现 SRD的 PWM调压调速的原理。实验证明 ,该方案控制方便 ,可靠性高 ,调速范围较宽 ,简单易行 ,特别适用于小功率开关磁阻电动机的调速系统。     

模糊滑模变结构控制在开关磁阻电机中的应用

开关磁阻调速电机系统（简称SRD）是一种新型的电动机调速系统。该系统优点突出，应用范围十分广泛，对其原理和控制方法的研究有这十分重要的作用。由于SRD是一个其型的非线性系统，难以建立精确的数学模型，常规控制器难以实现对其原理与实用性的探讨。综合各方面的因素，提出模糊滑模变结构控制方法，利用MATLAB仿真，仿真结果证明了该方法的有效性和合理性。     

基于DSP的模糊自适应PID控制SRD设计及实现

设计了一个开关磁阻电机调速系统(SRD).利用DSP的高速采样及快速运算功能,通过位置检测和电流检测进行速度和电流的双闭环控制;采用模糊自适应PID控制实现速度调节,提高系统的动态性能.实验结果表明,系统速度超调小,稳态和动态性能好.     

开关磁阻电机调速系统的软硬件设计

介绍了以TMS320F2407芯片为核心的高性能数字化SRD控制器的设计,给出了硬件电路设计和软件设计策略,并对其中功率变换器的设计、驱动电路设计给出了详细说明。本系统具有良好的调速性能和控制特性。     

纯电动汽车车载电源性能在环测试平台研究

为研究纯电动汽车车载电源性能,提出并搭建了由异步电动机和直流电动机组成的在环测试平台.异步电动机用来模拟纯电动汽车的牵引电动机,直流电动机用来模拟汽车行驶时的阻力和惯量,对异步电动机和直流电动机分别实施转速控制和转矩控制.分析了电动汽车行驶工况,给出了简单循环工况下参考转速、转距和功率.设计了异步电动机调速系统转速控制器和电流控制器,建立了异步电动机调速系统的数学模型,提出了基于自适应模糊神经网络控制的异步电动机调速系统.仿真和实验结果表明,基于自适应模糊神经网络控制的调速系统明显优于PID控制的交流调速系统,在环测试平台能够较好跟踪参考转速和参考转距的变化.     

基于DSP的开关磁阻电机速度控制器的设计研究

把数字信号处理器DSP应用于开关磁阻电机调速系统SRD中,该系统利用DSP高速采样及高速运算的特点,用脉冲宽度调节PWM技术的控制方法实现了速度闭环控制.主要研究通过位置反馈实现闭环速度控制;采用TMS320LF2407芯片作为控制芯片,组成具有人机交互接口的硬件电路;采用模块化编程的方法编写了控制算法和接口电路的程序,从而实现了开关磁阻电机SRM的全数字化控制.     

龙门刨床主运动控制方法探析

本文探析了龙门刨床主拖动系统的四种控制方式:电动机扩大机一发电机一电动机组(K—F—D)系统;全数字直流调速系统;交流变频调速系统;开关磁阻电动机调速(SRD)系统。指出了它们各自的优缺点及龙门刨床主拖动系统控制的发展方向。     

转台双闭环调速系统的仿真设计

本文运用MATLAB的仿真功能对古典法的双轴精密伺服转台的速度控制进行了研究,古典法是目前在伺服系统的工程实践中应用最广泛、最成功的方法.然而传统的设计方法工作量大,系统调试困难.文中利用MATLAB中的SIMUL IN K模块对系统进行模拟仿真辅助对调速系统的设计.为了提高调速系统的控制精度,在控制方法上选用电流内环和转速外环的双闭环调速系统.考虑到在对转速环进行仿真时要将电流环作为其中的一个部分,因而在建立电流环时利用MATLAB的子系统模块将电流环封装成一个子系统.利用MATLAB对系统仿真在很大程度上地减少了系统设计和调试的强度,并且仿真的结果也证明了采用该方法对转台调速系统设计是可行的.     

开关磁阻电动机调速系统控制器的设计

介绍了开关磁阻电动机调速系统(SRD)的特点及组成，对控制器的硬件电路及软件进行了设计．控制器以AT89C51为主控单元，采用硬件模拟PI双闭环调节，发出相通断信号和脉宽调制(PWM)信号，并和电流、电压等保护信号以及斩波信号相结合，实现对主功率元件的通断控制．软件采用模块化编程，提高了程序的通用性和可读性．     

浅谈KCBYS型开关磁阻电动机调速系统

介绍了开关磁阻电动机调速系统(SRD)的各个组成部分和功率变换电路应具备的条件,阐述了该系统的功率变换电路和系统控制结构图,给出了系统应用的控制方式、位置检测电路和电流检测的方法。     

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     

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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Brief Introduction to “Journal of Jilin University( Science Edition) ”

<正>"Journal of Jilin University(Science Edition)"is a comprehensive academic journal in the fields of science sponsored by Jilin University and administrated by the Ministry of Education of the Peoples Republic of China.The journal started publication in 1955.The original name at starting publication was"Journal of Natural Science of Northeast People University",which was changed into"Acta Scientiarum Naturalium Universitatis Jilinensis"in 1958 owing to the name change of the university.The present journal name has