无损耗电阻器的Pspice仿真研究

在建立无损耗电阻器数学模型及应用算法的基础上，利用Pspice软件对无损耗电阻器进行仿真研究，实现了动态电路的特性校正，大大减小了电路的能量损耗．     

一种计及损耗的变压器非线性模型

建立了一种计及损耗的变压器模型，用线性电阻、电感的串联模拟漏阻抗，用非线性电阻和非线性电感的并联模拟励磁支路，并提出建模算法，由变压器空载试验测得的电压、电流有效值和功率损耗，得到非线性电阻和非线性电感分段线性化的瞬时值特性曲线．应用该变压器模型和另两种模型，分别对330kV系统中的切除空载变压器过电压进行了仿真，对比计算表明，计及变压器铁损的非线性后，切除空载变压器过电压有明显的降低，过电压的幅值由忽略铁损的723．099kV和用线性电阻模拟铁损的582．036kV，降低到铁损的非线性模型的396．519kV．该变压器模型有助于准确地对电力系统中涉及变压器饱和特性的现象进行研究．     

免损电源的研究

简述了无损耗电阻元件的特性,提出了无损耗电阻用于产生免损电源方面的理论,建立了免损电源的数学模型和电路模型,并从理论上分析,实验中验证了免损电源的特性及其可行性。     

有源滤波器中LCL滤波参数选择和匹配

根据LCL滤波器低频与高频的不同特性,提出一种针对高、低频分别对总电感进行设计的方案. 再分析LCL滤波器的总电感分配、阻尼电阻对阻尼损耗以及控制系统性能的影响,提出基于阻尼损耗和系统稳定性的阻尼电阻匹配方法. 仿真及实验验证了该参数选择的有效性.     

提高鼠笼转子横向接触电阻测试精度的方法

鼠笼式异步电机导条和铁心间的接触电阻(简称横向接触电阻)Rc的大小,直接影响横向电流损耗的数值,后者在批量很大的小型斜槽式铸铝转子异步电机总的附加损耗中占有相当大的比重,Rc对转矩特性也有明显的影响。因此尽可能精确地测定鼠笼转子的横向接触电阻,可以更好地控制其数值,并为计算和减小电机的附加损耗、改善电机的转矩特性创造良好的条件,但目前国内在这方面的工作开展较少,和国外相比还有相当大的差距。     

无损耗电阻器的端口特性及应用

对无损耗电阻器的特性和功能进行了分析和探讨,建立了无损耗电阻器的数学模型和应用算法,并用无损耗电阻器代替电路中的电阻器,实现了动态电路的特性校正,大大减小了电路的能量损耗·实验结果验证了特性分析和算法的正确性,说明了无损耗电阻器可用于各类电系统及自动控制系统·     

空心电感损耗电阻频率特性研究

空心电感损耗电阻频率特性研究金轶锋（渭南师范专科学校物理学系，陕西渭南７１４０００；作者，男，４２岁，讲师）在交流电路中，由于介质损耗及分布电容的影响，空心电感的损耗电阻大于直流电阻，且随电源频率的升高而增加．损耗电阻随频率的变化关系，称为损耗电阻的...     

分布式电网中风电逆变器无源无损缓冲电路的研究

分布式电网中逆变环节发挥着举足轻重的作用,而功率开关的安全问题直接影响着逆变器的可靠性,因此逆变器开关缓冲电路的设计至关重要。传统缓冲电路主要以缓冲电阻消耗关断电压,损耗大,能量利用率低,介绍了一种无源无损缓冲电路,缓冲效果良好,能量损耗低。通过Matlab软件和样机实验分别对其进行分析测试,验证了其缓冲效果和特性,从而为开关缓冲电路设计提供借鉴。     

电容器的电压跃变与能量转换

本文分析了电容器电压跃变时伴随的冲激电流的能量转换，并以脉冲补偿分压器为例进行了讨论，指出，在计算有电容电压跃变的能量损耗时，除计及集中参数的电阻元件的损耗而外，冲激电流在分布电阻及电磁辐射上的能耗不可忽略。     

无取向硅钢片损耗特性模拟研究

磁性材料损耗特性的精确模拟对提升电气设备的效率和性能具有重要意义,受到了中外相关学者的广泛关注。基于经典的Steinmetz经验公式,提出了一种改进的损耗模型,该模型充分考虑了频率与损耗之间的关系,将损耗模型的计算参数表示为频率的函数。然后应用该模型对不同激励频率下无取向硅钢片的损耗特性进行了模拟研究。并将模拟结果与实验结果进行了对比分析,验证了该模型的有效性,为无取向硅钢片损耗的精确模拟提供了理论依据。     

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