电动机软启动器及其应用

电动机软启动器已逐渐替代传统降压启动方式，文章简述了新型软启动器的功能、特点，指出了软启动器与变频器的区别，并提供了软启动器的使用实例。     

软启动工作原理及其在煤矿的应用

本文介绍了软启动器的工作原理，分析了软启动器在煤矿中的应用前景，并对软启动器的节能及应用中遇到的问题进行了分析。     

软启动器在实际应用中的改进与完善

本文通过新型控制软启动器在轧钢厂大型电动机中的应用情况,针对软启动器出现的问题提出了改进意见和观点,对于完善软启动器在该领域的控制功能和普及应用将起到积极作用。     

软启动技术及其在城市防洪排水泵上的应用

根据软启动器体积小,转矩可以调节,启动平稳冲击小、软停机功能等优点,选择一种合适软启动器,简要介绍软启动器在城市防洪排水泵上的应用。     

基于单片机实现的交流调压及其在交流电机软启动器中的应用

将交流调压的基本原理应用到了异步电动机软启动器中,分析了软启动器的硬件系统结构框图和软件实现方法,同时设计了一种利用高速光耦取代同步变压器实现同步脉冲和触发脉冲的硬件电路,使软启动器真正实现了全数字化.     

电动机软启动器的使用分析

本文通过分析软启动器的工作原理及常用的几种启动方式,阐述了软启动器的使用及选型时应注意事项。     

基于AT89C2O51的软启动器设计

介绍了一种用AT89C2051单片机实现的经济型软启动器的设计思路,并介绍了软启动器的原理,系统的硬、软件构成.     

浅议软启动器在矸石破碎机控制系统中的应用

与传统的启动装置相比,软启动器因其具有的体积小、冲击量低、转矩可调等优点,更有利于电机设备软起、软停、及安全保护与系统节能等各种功能的实现.该文介绍了软启动器相较于传统变频器及降压启动装置的技术优势,并对其工作原理、启动方式、及功能特征作出了进一步的分析,提出了软启动器在矸石破碎机控制系统中的应用方法,并对其实践效果进行了总结.     

矿用防爆型变频软启动器的设计

文章首先分析了传统电机启动时存在的诸多缺点,产生了防爆型变频器软启动器的构思,接着介绍了本次设计方案所涉及的原理和特点,提出了有级变频软启动器的设计思路,最后从系统硬件设计和软件控制流程两个方面对设计方案做了较详细的阐述,对今后开发矿用防爆型变频软启动器的设计提供了借鉴。     

DWR-1型电机软启动器的技术特点分析

本文介绍了DWR-1型电机软启动器的工作原理和技术特点,从而论证了DWR-1型电机软启动器,保护功能齐全,软启动效果好,性能可靠、经济合理。     

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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