电动机修理与测试

电动机在工作中会出现许多故障,如果不及时处理将会产生严重的生产事故.因此,对电动机出现的故障必须及时进行修理和测试.本文对电动机的修理、测试及常见故障分别进行了论述.     

高压交流电动机定子绕组故障的原因分析及处理

针对高压交流电动机在电力生产中的重要地位及发生事故后损失巨大、修复时间长、修理费用高的情况，结合某电厂在高压交流电动机的维护、检修方面取得的成功经验和笔者工作实践，对高压交流电动机定子绕组故障的原因从制造质量、引起主绝缘老化的因素、电源异常对电动机的危害、电动机运行与维护等方面进行了全面分析，并提出了减少高压交流电动机定子绕组故障的有效措施。     

论火电厂高压电动机故障及处理方法

随着经济的发展，国家对电力的需求越来越高，在火力发电中，电动机运行常常会出现很多的故障，本文是作者在近几年的工作中就火电厂电动机运行故障及处理的相关问题进行了简要的阐述和分析，以供参考！     

计量器具、测试仪器电气部分的修理方法和步骤

本文简要叙述了对计量器具、测试仪器的修理步骤，并根据计量器具、测试仪器所呈现的故障现象，采取常用的几种修理方法，将故障予以排出解决。     

三相异步电动机常见的电气故障与维修方法

在工业生产的过程中,因为三项异步电动机具有价格低廉、运行稳定、结构简易等方面的特点,所以使用非常的普遍。不过三相异步电动机在经过长时间的运行后,会出现各类运行故障,为了避免故障进一步扩大,就需要快速的对出现故障的原因进行分析处理。从而确保设备可以保持一个正常的运行状态。基于此该文对三相异步电动机常见的电气故障和维修方法进行探讨。     

矿用电机车牵引电动机故障原因及防治措施

根据对电机车牵引电动机故障的统计,分析了故障部位发生故障的原因,并提出了使用前检查、使用中正确操作、定期维护修理等防治故障的措施.     

浅谈一种基于AR模型的电厂电动机故障诊断新方法

电动机是电厂的重要设备,对发电厂的电动机故障进行诊断有重要意义。本文采用虚拟仪器系统作为开发平台,根据电动机振动信号的特点,对其进行虚拟诊断测试,在实际测试中,提出倒谱分析方法,是基于自回归AR模型的一种电机振动信号检测方法,首先是AR建模,并进行阶次预测和系数预测,得到相关参数;再进行倒谱变换,快速准确地提取出所需要的频谱信息,从而判断电机是否出现故障。     

三相异步电动机的常见故障与检修方法

在三相异步电动机运行过程中,其不仅会出现机械故障,更会出现电气故障,其中机械故障主要为机壳、风扇、轴承、转轴等的故障,而电气故障主要因转子绕组或是定子绕组的故障造成。基于此,文章结合实际,从三相异步电动机的常见故障入手,首先简要分析了三相异步电动机的基本概述,其次阐述了三相异步电动机的常见故障,最后提出了三相异步电动机常见故障的检修方法。     

应用ORCA结构测试FPGA逻辑单元的方法研究

给出了一种基于BIST技术测试FPGA逻辑单元CLB的方法．利用本文给出的0RCA结构对CLB进行测试，可以尽可能地对CLB中的故障进行完全测试，提高测试效率，减少了测试成本．文章给出了应用这种方法进行测试的配置结构、故障覆盖率和测试中出现的问题及其解决办法．实验结果表明，文中的方法是可行的．     

浅谈三相异步电动机定子绕组故障分析和处理

三相异步电动机定子绕组在运转过程中,会出现各种故障。如何在掌握三相异步电动机运行情况的基础上,对电动机故障进行处理,对保证电动机正常运转具有十分重要的意义。本文就绕组缺相运行、过载运行、绕组接地、绕组相间短路、相间匝间短路、绝缘电阻偏低等6种情况进行了分析,重点介绍了在检修时的故障检查分析及相应的处理手段。     

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