大容量同步电动机的软起动控制

为了减小大容量同步电动机起动电流并缩短起动时间，提出用恒剩余角控制方法代替恒超前角控制方法，分析了恒剩余角数字控制系统中的一些主要问题： 稳定性、转子位置信号生成、逆变器控制及励磁控制，并给出了解决方法。用在线辨识方法获得的电机参数计算换流超前角，提高了计算的准确性。设计制作了一台７．８ Ｍ Ｗ 同步电动机软起动的数字控制系统。分析和现场运行表明，采用恒换流剩余角控制是减小起动电流并缩短起动时间的有效方法     

自控式同步电动机高性能控制方式的实现

分析了恒换流剩余角和恒气隙磁通控制相结合的高性能控制方式。提出了基于端电压相位检测的恒换流剩余角控制方法，讨论了端电压相位检测的低速运行问题。得出了计及气隙磁场饱和效应时恒气隙磁通控制的励磁调节规律，给出了一种无刷励磁结构及馈电主回路。采用８０８６微机与８０３１单片机构成的全数字控制系统实现了恒换流剩余角和恒气隙磁通控制。实验结果表明采用此控制方式的自控式同步电动机可获得最优性能指标。     

液压蓄能式风力机组并网转速解耦优化控制

针对在风速、同步发电机负载变化情况下,液压蓄能式风力机组并网转速控制问题,提出一种新型并网转速控制方法——解耦广义预测优化控制方法（Decoupled Generalized Predictive Optimization Control, DGPOC）.首先,DGPOC利用基于广义预测的前馈解耦方法解除变量马达摆角和蓄能器比例阀开度之间的耦合关系,进而调节蓄能器比例阀,依靠蓄能器吸收波动流量,同步调节变量马达摆角实现恒转速控制,解决因风速、同步发电机负载变化引起的变量马达转速波动问题; 其次,将蓄能器比例阀的能量损耗作为性能约束项,加入到优化目标函数中,求取最优控制量,从而提高液压蓄能式风力机组风能利用率; 最后,利用建立的MATLAB-AMESim联合仿真实验平台验证DGPOC方法的有效性.实验结果表明： DGPOC方法不仅可以实现变量马达摆角和蓄能器比例阀开度两个变量的解耦,提升变量马达转速控制的快速性及鲁棒性,而且能够降低系统的能量损耗.     

基于国产荧光分光光度计应用导数--恒能量同步荧光法测定苯并（a）芘

该方法利用同步荧光分析法中的导数-恒能量同步荧光法，基于上海棱光技术有限公司F97Pro荧光分光光度计产品，通过对食品样品进行简单的萃取处理，在选定的同步荧光扫描参数下直接测定，运用标准加入法定量计算，实现了对食品中苯并（a）芘的快速测定。该方法检出极限为0.1n g/g。     

新型扫描电镜分辨率的蒙特卡罗模拟

用蒙特卡罗方法模拟计算了利用高能同轴背散射电子的扫描电子显微镜的空间分辨率，点源模型的模拟结果显示小的入射能量、探测能量窗口及探测角值对应较好的分辨率，对由两种不同元素构成的边界而言，模拟结果显示：好的分辨率对应较小的探测能量窗口和较大的探测角，最佳的入射能量是10keV。在合理优化电镜工作参数的前提下，最佳空间分辨率可达束斑大小的量级。     

水中多环芳烃混合物快速恒能量同步荧光分析

建立了咔唑、1,2-苯并蒽、苯并[a]芘和2,3-苯并蒽四种多环芳烃同时快速测定的恒能量同步荧光分析法.选择能量差Δυ-=1400cm-1,仅需一次扫描,就可同时鉴别和定量测定四种多环芳烃.四种多环芳的线性范围依次为0.5-300ng·mL-1、0.2-250ng·mL-1、0.05-50ng·mL-1和0.5-350ng·mL-1,检出限在0.0046-0.023ng·mL-1之间.该方法简单快速、灵敏度高,无需对多环芳烃混合物进行预分离,可用于实际水样的直接分析,效果良好,回收率为83.0%-105.3%.     

同步锯齿波发生器电路的改进

利用NE555定时电路和恒流充电的积分单元电路，设计了一种线性良好的锯齿波发生电路；该电路克服了文献[1]中电路的缺点，实现了作为扫描电路所要求锯齿波的同步与良好的线性．     

凸轮驱动的液压全可变气门机构研究

考虑到电液式可变气门大多需要高响应性的电磁阀,成本高昂控制复杂,而目前市面上技术较为成熟且应用较广VVT和VVL技术,对于配气参数的调节是有限且有级的.作者设计了一种凸轮驱动的可变液压气门机构,并进行了台架试验研究.该可变液压气门机构的提前泄油量的调节可以使气门升程和关闭角同时可变,而延后压油量的调节可以使气门升程,开启角和关闭角均可变.结果表明,所设计的可变气门机构实现了气门开启角,关闭角和气门升程的配气参数全无极可变,并且该系统成本低廉、控制方便.      

红外导数光谱法测定二甲苯异构体含量

<正> 导数光谱法(Derivative Spectrometry)是近年来发展较为迅速的一种技术。早在50年代中期,Giese等就利用微分方法解决了光谱的重叠问题。随着现代电子技术的迅速发展,特别是分析仪器上使用了计算机,导数光谱的应用更为广泛。尤其在可见——紫外分光光度法中的应用更为突出。目前导数光谱法在红外     

聚苯胺薄膜电极的制备及性能研究

文中在Pt电极上用循环伏安、恒电位和恒电流电化学聚合方法制备聚苯胺(PAn)薄膜,对PAn膜电化学合成条件进行了探讨。结果表明:循环伏安法的扫描电位上限、扫描速度、恒电位法的聚合电位、恒电流法电流密度等因素对PAn膜的物理和循环伏安特性都有很大的影响,同时酸性介质的浓度以及氯离子搀杂也极大地影响着PAn膜的性能。     

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     

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