单相电子式预付费电能表的作用及在现场应用中的优缺点分析

从单相电子式预付费电能表的工作原理入手,阐述了电子式预付费电能表的组成及作用。分析了单相电子式预付费电能表在现场应用中所体现出的优缺点,为实际工作中在现场是否要安装单相电子式预付费电能表提供理论依据。     

探析普通单相电子式电能表的“停走”问题

作者根据实践工作经验,针对普通单相电子式电能表两种不同供电方式工作电源的基本原理及受电网谐波影响的原因作比较分析,并提出了对普通单相电子式电能表工作电源进行改进来消除电网谐波的影响。     

含有单相380V电焊机负载的用电量计量方式分析

电子式电能表已广泛用于电能的计量,但对于380 V电焊机,由于其接入电压与运行状态的特殊性,当采用不同的计量方式或不同功能的电能表时可能造成电能的错误计量.本文分别用3只220 V电子式单相电能表、1只三相四线电子式电能表、1只三相三线电子式电能表三种计量电焊机用电量的方式进行了分析.     

一种新型电子式电能表的研究

介绍了新型基波全电子式电能表的设计方法，分析了电子式电能表发展情况和发展趋势，讨论了在谐波存在下电能计量不准确的原因，阐述了新型基波全电子式电能表的设计方案，电能计量部分确定采用DSP芯片通过软件编程实现低通滤波和电能计量，软件采用适于本表计的前后台软件结构。     

装表接电及防窃电分析

分析了全电子式电能表的特点与安装步骤,阐述了窃电的分类及其危害,介绍了全电子式电能表的防止窃电功能,提出了加强装表接电管理防止窃电的措施。     

电气化铁路负荷特点及电能计量方式的探讨

我国的电气化铁路牵引负荷具有波动性、非线性、冲击性的特点,采用单相工频25kV供电,容易对电力系统造成负序污染和谐波效应,造成了供电电流波形和电压波形的畸变,对电能计量误差造成直接影响。基于此,介绍了电气化铁路,并对单相工频负荷、单相冲击负荷以及单相整流负荷的电气化铁路负荷特点进行分析,同时对包括感应式电能表计量方式和电子式电能表计量方式的电能计量方式进行探讨,以此保证电气化铁路以及接触网的安全运行。     

电子式电能表的普及应用及常见故障分析

本文通过对电子式电能表代替感应式电能表的原因介绍,说明电子式电能表是电能表技术发展的必然产物,结合实际提出了电能表的选型问题,并对机械式电能表和电子式电能表的特点进行了论述。最后对电子式电能表的常见故障进行了分析。     

智能型电能计量表的工作原理及其发展趋势研究

电能计量表根据其工作原理的不同可以分为电解式、感应式和静止式三大类,在实际使用中测量交流电能主要采用感应式和静止式。感应式电能表其测量原理和结构存在一些制约性的,使此类电表的功能扩展和精度提高受到限制;静止式电能表的测量原理是将单相或三相交流功率采用全电子方式转换成脉冲或其他数字量后再进行相应的数据处理,此类电表又称全电子式电能表,它具有线性度好、测量精度高、过载能力强、功耗低、功能扩展容易、可测频带宽、体积小以及重量轻等诸多优点。对于电能表而言其测量工作原理不同,仪表的性能,制造成本也会有所差异,因此随着对用电管理要求的提高,感应式电能表正逐渐被静止式电能表所取代。     

新一代电子式单相交流电能表

本文简要介绍了电子式单相电能表的原理和电路设计，它具有精度高，能耗小、防窃电、技术升级容易等优点，是一种理想的电能计量的更新换代产品。     

全电子式多功能电能表应用一例

运用新型全电子式多功能电能表对企业经济用电降成本有重大意义。     

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.     

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     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

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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