电力直流系统模拟量开关量的采集

电力直流系统是变电站安全运行的基础，随着变电站数字化、智能化程度的不断提高，对站用电源的管理也提出了新的、更高的要求。而管理的的基础，就是设备能准确、高速的反应当前设备的电压、电流、开关状态等信息。做到设备不死机，不停机，干扰不误报等。随着微电子技术、计算机和通讯技术的飞速发展，新器件的研制、生产周期的日益缩短。为了满足工业自动化，新技术、新器件不断应用到新产品中。模拟量采集包括直流电压和电流。开关量采集包括开关的分合，继电器的投入切除等。     

软开关双丝脉冲熔化极活性气体保护焊逆变电源

根据双丝脉冲熔化极活性气体保护（MAG）焊的工艺要求，将软开关技术、双闭环控制技术以及现场总线控制技术相结合，研制了一套软开关双丝高速脉冲MAG焊电源，并应用计算机信息测试采集平台对该系统进行测试．结果表明，系统具有良好的静、动特性，主从机协同控制稳定可靠，完全可以满足双丝高速脉冲MAG焊的技术要求．     

多路开关遥测遥控系统

提出一种通用于工业自动化中的多路开关遥测遥控系统，主要由多路开关采集发送单元和多路开关数据接收单元组成。每对收发单元可实现１５个开关量的测控，并可以方便地进行级联或并联以组成更多开关量的测控系统。系统全部由硬件构成，具有体积小、成本低、抗干扰、灵活方便、测控距离远、通用性强等优点。     

VD-MOS高频感应加热装置的研究

以功率MOSFET为开关元件 ,采用多管并联方式研制出高频感应加热电源。该电源逆变控制采用了锁相技术 ,利用锁相技术使功率MOSFET实现零电流开关 ,并使逆变器的工作频率跟踪系统因有谐振频率。使得该电源始终能运行在负载功率因数为1的状态 。     

混凝土冻融试验机及监控系统

设计了混凝土冻融试验机及监控系统.下位机由控制器、温度传感器、开关控制电路以及电源监控电路组成,其中ATmega32控制器负责信息的采集,并通过串口与上位机通信.上位机软件基于Lab Windows/CVI平台开发,可实现温度信息及电源信息的实时采集与处理、数据存储及历史查询等功能.系统根据上位机设定的冻融循环次数对混凝土试件进行冻融破坏实验,根据结果可确定混凝土的抗冻等级.采用混凝土标准件进行实验,验证了系统的可靠性.     

基于数字信号处理器和LabView的焊接电源系统

介绍了基于数字信号处理器(DSP)控制的气体保护焊接电源，以及在此数字化焊接电源的基础上，采用实验室虚拟仪器工程平台(LabView)技术建立的焊接电源系统研究平台．通过数字信号处理控制和自调节以及柔性化的控制程序实现合适的电源外特性、网压补偿、焊接电压及电流的反馈、送丝机构等，大大增强了焊接电源的稳定性和可靠性；在基于虚拟仪器LabView技术建立的焊接电源系统研究平台上，对焊接过程中焊接电流和焊接电压信号进行采集，并加入时刻标定信号表示焊接过程的不同阶段．焊接过程实时采集和显示各个信号波形，并对焊接电流和焊接电压统计分析运算，得到焊接过程主要参数的概率密度分布图．实验表明，该系统工作稳定，满足研究工作需要．     

高频开关电源的数字化控制电路的设计

实现电源高频化的有效途径是采用软开关技术,本文通过分析电源电路中的软开关技术,在基于Buck变换器的基础上建立了移相全桥变换器的小信号模型,该模型具有较高的系统稳定性。最后给出了数字化控制系统的软件流程。     

开关式氙灯电源在电影放映系统中的应用

本文对开关式氙灯电源在电影放映系统中的应用进行了简要的分析,阐明了氙灯电源使用中必须达到的技术指标,分析了开关式氙灯电源的工作原理,并对使用中出现的问题给出了排解的方法,为更好地使用氙灯电源,提高放映系统的性能奠定了良好的基础。     

壁面移动自控车驱动系统

介绍了用开关式集成一体化电源构成的直流电机控制系统，并对该系统的功能及硬件系统的设计方法进行了阐述。     

VD-MOS高频感应加热装置的研究

以功率MOSFET为开关元件,采用多管并联方式研制出高频感应加热电源。该电源逆变控制采用了锁相技术,利用锁相技术使功率MOSFET实现零电流开关,并使逆变器的工作频率跟踪系统因有谐振频率。使得该电源始终能运行在负载功率因数为1的状态。     

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.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

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