电荷泵技术在高强度气体放电灯电子镇流器中的应用

电荷泵功率因数校正(CPPFC)技术的发展，使得原双功率级有源校正变换电路可简化为单功率级变换电路。该文研究了CIC(Continuous Input Current)CPPFC技术在高强度气体放电灯电子镇流器中的应用，解决了传统双功率级电子镇流器结构复杂、成本较高的问题。提出了一种适用于高压钠灯的动态模型，基于此模型对不同功率的电子镇流器进行了仿真研究。仿真与实验结果表明，这种单功率级结构的电子镇流器的功率因数能够达到0．97，THD值小于12％。     

具有软开关的高频电荷泵功率因数校正电路

对电荷泵电路实现功率因数校正(PFC)的原理及其实现条件进行分析，提出一种具有软开关的高频电荷泵PFC电路，并详细论述该电路的工作原理及其软开关实现；最后对该电路在电子镇流器中的应用电路进行仿真和试验．研究结果表明：电路的功率因数高，谐波含量小，是一种结构简单、性能优良的功率因数校正方法．     

一种新型的ZVS单级功率因数校正变换器

为了提高单级功率因数校正变换器的效率、减少抑制电磁干扰,文中通过把传统的Boost PFC变换器和非平衡半桥DC／DC变换器结合在一起,采用级联技术构造出一种新型的ZVS单级功率因数校正变换器．最后制做了样机并进行了实验验证．实验结果表明,这种电路具有结构简单、易控制、成本低等优点,可在实现高功率因数的同时实现全部功率开关管的软开关．     

L6562实现的无桥BoostPFC电路

在无桥Boost功率因数校正(PFC)电路的基础上,提出了具有高效率、高功率因数的新型无桥Boost功率因数校正电路拓扑,在理论分析的基础上应用Saber进行仿真验证。设计1台85~132 V交流输入,380 V/35 W输出的实验样机。样机采用L6562芯片实现临界导通模式的功率因数校正,进一步验证该无桥变换器的良好电气特性。     

新型的单相Buck电路实现功率因数校正

提出了一种不连续电容电压的单相Buck电路实现功率因数校正方法，在不控整流桥后采用LC滤波，选择合适的输入滤波电容值，电容电压工作在不连续模式下，同时使得输入电容电压峰值跟随整流输入电压的包络，可获得单位功率因数．在输出滤波电感后采用并联谐振滤波，解决了Buck电路中输入电压低于输出电压时输入电流波形的畸变问题，使得输入电流为正弦波，同时消除了Buck功率因数校正电路中普遍存在的输出电压100Hz的交流成分．该变换器电路控制简单，由恒定占空比的脉宽调制(PWM)控制．仿真结果和试验电路验证了所提方法的有效性．该电路功率因数为0．99，电流THD值为4％．     

三相电路功率因数的校正

在Ｔｅｎｔｉ的瞬时功率理论基础上，设计了一种用于功率因数校正装置的补偿电流参考信号检测电路，并在实验室设计安装了１台小容量并联型功率因数校正装置，其主回路采用电压型三相ＤＣ－ＡＣ逆变器，并采用改进的自适应电流跟踪型ＰＷＭ控制电路．实验结果表明，该装置达到了很好的补偿效果，验证了设计的正确性     

一种单级DCM高功率因数非平衡半桥变换器

对一种由非平衡半桥电路构成的新型单级AC／DC功率因数校正(PFC)变换器的工作模态及性能进行了理论分析,采用SIMetrix数模电路仿真软件进行了数字仿真,并在样机上进行了试验．仿真及试验结果表明,该电路工作于不连续导电模式,具有很好的功率因数校正性能以及软开关效果,因此有很高的功率因数及效率．     

Boost型PFC的实验研究

从功率因数的定义入手，对Boost型开关电源功率因数校正器（PFC）进行了理论分析和实验研究，实验校正后的波形较好，基本上是标准的正弦波，达到了预期的效果，理论分析和实验结果是一致的。     

一种新型的单相三电平单级功率因数校正电路

回顾了单级功率因数校正电路的发展状况，总结了多种单级PFc（功率因数校正技术）变换电路的优缺点，指出目前单级PFC变换电路需要解决的主要问题，并就此问题介绍了一种新型的单相三电平单级PFC电路，分析了其工作过程，并给出了仿真和实验结果。     

基于UC3853的功率因数校正的设计

设计基于UC3853芯片的有源功率因数校正电路,介绍了装置的工作原理,给出了设计方法,并研制了一台实验样机.实验结果表明,功率因数校正效果达到了预期要求.     

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     

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