传导电磁干扰噪声综合解决方案

为有效抑制传导电磁干扰噪声,设计了一种能够较好抑制共模噪声的优化噪声分离网络,采用单电流探头法提取噪声源内阻抗,并从技术与经济角度对各类分离网络、EMI滤波器性能进行决策参数建模,据此设计合适的传导电磁干扰综合解决方案.进行了噪声分离网络共模抑制比特性试验和基于单电流探头测量的EMI噪声源内阻抗提取试验,并开发了传导EMI噪声综合处理系统.结果表明,该综合解决方案可以实现对传导噪声的有效分离及噪声源内阻抗提取,同时可兼顾技术性与经济性而达到优化;所建立的噪声综合处理系统能较好完成噪声综合解决方案,对传导电磁兼容有参考意义.     

电力线通讯辐射噪声的预估与抑制

介绍了电磁干扰(EMI)噪声分离网络在预估与抑制电力线通讯中系统辐射电磁干扰噪声方面的应用.首先,利用电磁干扰噪声分离网络对电力线通讯系统中的电磁干扰总噪声进行模态提取,获得该噪声中的共模分量和差模分量,并根据相应的数学模型将测量得到的噪声电压信号转化为噪声电流信号.然后,利用共模噪声电流与辐射场的关系模型对系统的电磁干扰辐射噪声进行预估.实验结果表明:通过提取引起辐射噪声的共模噪声电流,可较为准确地预估此辐射噪声;通过设计相应的EM I滤波器或采用铁氧体磁环,可实现对共模噪声电流的抑制,从而达到抑制系统中辐射电磁干扰噪声的目的;与滤波器相比,铁氧体磁环抑制辐射噪声的效果更为明显.     

开关电源的电磁兼容性设计

对开关电源的电磁干扰波形进行了分析,建立造成共模干扰、串模干扰的电路模型,然后提出了具体解决方案:利用单级或双级EMI滤波器滤除共模干扰和串模干扰,并介绍了选择EMI滤波器中元器件的方法。实验表明:利用简易的EMI滤波器可将电磁干扰衰减40 dBμV;使用改进后的EMI滤波器,能将电磁干扰衰减50~70 dBμV。     

PFC+半桥LLC电路传导共模EMI特性分析与抑制

为了研究开关电源的传导共模EMI特性,在分析交错并联PFC+半桥LLC电路传导共模噪声传输机理基础上,提出了磁元件可视为共模滤波器的新观点。理论分析了磁元件的共模滤波特性,通过优化设计变压器绕组结构,改善变压器容性分布特性,可提高变压器的共模噪声滤波能力;通过构造反相噪声源,补偿抵消原始噪声,可提高功率电感共模噪声滤波能力。最后,通过一台音频功放电源样机进行了实验验证,实验结果表明优化磁元件共模EMI滤波特性,可有效抑制电路的共模噪声。     

基于双面平行带线的绝对带宽不变频率可调带通滤波器

提出基于双面平行带线结构的电容加载绝对带宽不变频率可调平面带通滤波器,通过选取特定的耦合区域,使谐振器之间耦合系数满足绝对带宽不变的要求. 分别设计了工作在单端信号和差模信号下的滤波器. 结果表明,对于单端信号滤波器,其3 dB绝对带宽（|S₁₁| <-3 dB）在0.97 ~1.43 GHz的中心频率调节范围内约为80±4 MHz;对于差模信号滤波器,其3 dB绝对带宽（|S_dd11| <-3 dB）约为91±3 MHz,对共模噪声的抑制低于-20 dB.      

电力线载波通信差模传导骚扰测试方法研究

目前电网中负载传导骚扰测量与门限值标准都基于传统的混合模方式,包含共模和差模骚扰。电力线载波通信系统中,信号通常以差模方式进行传输,共模骚扰能够得到有效抑制,而电网负载中差模骚扰是影响电力线载波通信性能的主要因素之一。提出了一种基于电力线载波通信耦合装置的差模传导骚扰测试方法,该电力线耦合装置能够有效地对共模信号进行抑制,对差模信号进行提取。测量并研究了不同类型家用电器的差模骚扰特性,对比分析了所提出的差模骚扰和传统混合模骚扰测试结果。结果表明,差模传导骚扰相较于传统骚扰具有更大的骚扰幅值。所提出的测试方法能有效地对家用电器的差模传导骚扰进行测试,为建立电力线差模传导骚扰限制标准提供理论依据和实验手段。     

基于插入损耗法的噪声源内阻抗建模及误差分析

针对传导电磁干扰滤波器设计中人工电源网络阻抗、噪声源内阻抗、负载阻抗与EMI滤波器的阻抗匹配问题,建立了插入损耗法的误差理论模型及其等效电路.分别分析了串联和并联插入损耗法的测量精度及其系统误差,据此提出了相应的测试条件和测试方法,即当被测阻抗远大于负载阻抗时,采用串联插入损耗法;当被测阻抗远小于负载阻抗时,采用并联插入损耗法;当被测阻抗与负载阻抗相当时,可改变负载阻抗.理论与试验研究表明,该方法在适用范围内能够快速有效地提取EMI噪声源内阻抗,从而实现噪声源与EMI滤波器之间的最大阻抗适配,为EMI滤波器的设计及传导电磁干扰噪声抑制提供理论依据.     

一体化电机系统中传导干扰抑制方法的研究

为了抑制一体化电机系统中的传导干扰，分析了一体化电机系统传导干扰的产生机理及其耦合途径．根据干扰机理、耦合途径及干扰源的分布，分别采取相应的抑制措施．功率器件的电压过冲和电压变化率可以通过缓冲电路来进行抑制．基于传导干扰的耦合途径不同，以变流器为界，前后分别从漏电流和共模电压的角度进行抑制，采用有源滤波来补偿漏电流和消除共模电压．在理论分析的基础上，设计了用于抑制传导干扰的新型滤波器．实验结果证明，增加缓冲电路和滤波器后，一体化电机系统的传导干扰强度明显减弱．     

电动汽车电机驱动系统分布参数对传导电磁干扰影响研究

构建了电动汽车电机驱动系统传导电磁干扰测试平台,研究电动汽车电机驱动系统带载工况下分布参数对传导电磁干扰的影响.通过测试比较电机驱动系统带载工况下和空载工况下产生的传导电磁干扰,分析系统高低频差模干扰和共模干扰的传播路径,建立相应的等效电路,在频域内分析了传导电磁干扰产生的机理和分布参数对传导电磁干扰的影响.测试结果表明,适当增大电机控制器内部功率器件对地分布电容和直流动力线缆对地分布电容可减小系统产生的高频传导电磁干扰.      

差共模滤波器的平面无源集成

为了提升电源产品品质,在差共模集成滤波器的基础上,采用改变磁芯结构的方法对差共模集成电感平面化,推导了集成磁件的等效电路,给出了平面化集成磁件的设计结果,并用Saber软件对滤波电路进行仿真.该设计方法能够减小滤波器无源器件的体积与高度,提高磁件的利用率,为电力电子的系统集成提供技术支持.     

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