IGBT串联应用中动态过压的控制

对高压大功率变流设备中绝缘栅双极型晶体管（IGBT）串联应用的动态过压问题进行了研究．提出了一种基于磅磅控制原理的快速反馈控制方法对器件端压进行控制,以抑制串联器件间的动态过压,根据控制回路的特点,设计了一种实用的反馈信号交互电路。该电路可以为串联IGBT提供及时、准确的开关信号．将所提出的方法应用于交流感应电机的变频控制,结果表明,该控制方法具有较高的控制精度和较快的响应速度,可以满足实际需要,所设计的反馈交互等电路具有良好的可拓展性．     

一种串联有源电压质量调节器的直流电压泵升与移相控制

对一种串联有源电压质量调节器运行中直流侧存在的电压泵升现象进行了分析，并对采用移相补偿控制技术来抑制直流电压泵升时电源过电压倍数、负载功率因数、移相角及补偿电压大小之间的关系进行了理论研究．以低压配电系统用串联有源电压质量调节器实际装置为例，对上述各量进行了计算，获得了一组控制直流电压泵升的实用设计曲线．     

三相异步电机的电源断相、过压、欠压保护电路

本文对三相异步电机的电源断相各种保护电路进行比较分析后，利用电压采样原理设计制作出了一种实用、安全、可靠的三相异步电机电源的断相、过压、欠压保护电路。并对其工作原理进行了较详细的论述。     

ZＸ-315逆变弧焊电源可靠性设计

提出了提高ＩＧＢＴ控制的ＺＸ－３１５逆变弧焊电源可靠性的措施：主电路与驱动线路电隔离；设定空载电压、短路电流、过流过压情况下关断驱动脉冲。采用该措施，可保证ＩＧＢＴ在完全导流及彻底关断两种极限状态下工作，避免由于误导通使ＩＧＢＴ在半导通状态下工作以及过压或过流而造成的损坏。     

基于UC3842的开关电源输入过压保护电路

为了实现UC3842构成的开关电源具备输入过压保护功能,使电源避免存在安全隐患,利用UC3842芯片固有的基准电压源提供的电压和TL431,能在设计电气技术指标满足正常使用要求的条件下,可选择耐压相对较低的开关管,设计出电路结构简单、成本低廉、新颖实用的输入过压保护电路,同时通过实例分析和实验结果表明了该保护电路的可行性。     

多功能过压延时显示保护开关

多功能过压延时显示保护开关——简称:保护开关。本保护开关属于低压电器保护开关,是一种多功能过压延时显示保护开关。这种多功能过压显示保护开关,电源电压显示电路中的双色发光二极管,可显示欠压、正常电压和过压;过压保护电路中的压敏电阻有一固定阀值电压,能准确检测电源电压过压值,解决了目前低压电器开关存在的欠压、正常电压和过压不能显示,和过压保护值不稳定,易造成电器设备损坏和误动作的问题。     

VMOS管全自动不间断逆变电源

本文介绍一种全自动不同断逆变电源，该电源的逆变电路简单、性能可靠，采用ＶＭＯＳ管作用功率输出级，逆变效率高，控制电路在市电接通时，对负载供电，同时对电瓶充电，充满自停，能实验市电和逆变电源供电的自动转换，设有电瓶充电过压和欠压保护电路，实现了全自动控制，可作为家庭小功率应急电源。     

一种新型电气化铁路串联电容器保护间隙

随着电气化铁路的不断发展,串联电容器补偿装置在牵引供电系统中得到广泛应用,而电容器的过压能力较弱.提出了一种新型保护间隙装置,当发生过电压时,通过触发电路迅速启动.本装置能较好的满足电容器的过压保护要求,并在实际运行中取得了较好效果.     

全桥LLC串联谐振X光机高压直流电源

针对X光机电源的全桥移相拓扑结构存在占空比丢失问题,提出一种全桥LLC串联谐振变换器与单相双向对称倍压整流电路相结合的高频高压X光机电源。在主电路中,采用全桥LLC串联谐振、高压变压器、单相双向对称倍压整流电路;从理论上分析了零电压软开关工作条件,建立主电路基波等效(fundamental harmonic approximation,FHA)模型,并对主电路的参数进行设计。仿真结果表明：输出电压可以在40～120 kV内连续可调,不存在占空比丢失;输出电压上升时间短、纹波小。证明了所提出拓扑的正确性和可靠性。     

负载谐振式臭氧电源的微分-差分方程模型

为描述介质阻挡放电型臭氧发生器电路的实际工作过程,在分析一种移相全桥脉宽调制下串联负载谐振电源供电的臭氧发生器电路的基础上,提出了采用微分-差分方程来描述电路的工作过程,并给出了电路可能的工作轨迹.通过实验验证了用微分-差分方程来描述DBD电路的正确性.该方法不仅能描述电路的稳态工作而且能描述电路的动态工作过程.     

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.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

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.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

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.     

海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

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Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to