一种抑制气体绝缘开关装置暂态地电位升高的措施

在分析外壳地电位升高原因的基础上，提出了用电磁暂态程序计算外壳地电位升高的等值计算模型．通过对外壳地电位升高的计算，表明外壳地电位的升高足以危害与气体绝缘开关装置(GIS)相连的外围设备．为了防止外壳地电位升高对GIS的外围连接设备的影响，提出用线路金属氧化物避雷器限制快速暂态过电压的幅值，用氧化锌阀片来改善GIS与外围设备的连接方式以限制外壳地电位升高．计算结果表明，加装金属氧化物避雷器不仅可以抑制快速暂态过电压，而且可以较为有效地抑制外壳地电位升高，且氧化锌阀片的残压越低，其对外壳地电位升高的抑制效果越好．对国内某550kV GIS的外壳地电位升高进行了现场实测，结果表明计算波形与实测波形比较吻合．     

核电厂GIS中快速暂态过电压（VFTO）的影响及分析

随着GIS在核电厂的广泛应用，快速暂态过电压（VFTO）的危害引起了普遍的重视。特别是对于330kV以上的GIS，故障率有明显增加的趋势。目前国内外对500kV及以上的VFTO的特性、影响及防护措施做了大量的研究工作，为核电厂GIS中VFTO影响的研究提供了良好的参考和借鉴。但是随着GIS制造技术的进步，与早期相比，其结构与元件均发生了很大的变化，如GIS的“小型化”和“紧凑型”的出现，导致VFTO特性的改变，因此结合目前核电厂中GIS运行的具体情况，研究GIS中快速暂态过电压的影响具有非常重要的现实意义。     

特快速暂态过电压及其对主变的影响

由于操作全封闭SF6气体绝缘变电站(GIS)隔离开关而引起的特快速暂态过电压(VFTO)是GIS特有的一种过电压,对变电站内的设备特别是电感类设备如变压器等构成新的影响。该文在简述500kVGIS特快速暂态过电压产生的原因、影响因素、危害及其抑制措施的基础上,以江苏宜兴抽水蓄能电站500kVGIS变电站为例,采用PSCAD/EMTDC软件详细计算分析了多种操作方式下的VFTO。以相关文献的试验结果作为参考,讨论了VFTO对主变的影响。结果表明,由于连接主变与GIS的长电缆明显抑制了出现在主变侧的VFTO,该项目中涉及的VFTO对主变的影响不明显,不会造成主变的匝间绝缘击穿。     

工频试验变压器快速保护装置中限流电抗器的参数选择

工频试验时,试品放电后产生的恢复过电压最大值可达试验电压幅值的２ 倍．快速保护装置通过将试验变压器原边经限流电抗器快速短路的方法可有效抑制此类过电压．其中限流电抗器的参数决定了装置动作时短路电流的大小和过电压倍数．提出了优化选择该参数时应遵循的原则,建立了仿真计算的数值模型,给出了一种收敛速度较快的逐次估算逼近方法,并用电磁暂态程序对一套实际工频试验系统进行了仿真计算,结果完全达到了预期目标．     

500kVGIS变电站快速暂态过电压研究

采用ATP--EMTP对500kV GIS变电站GIS中隔离开关操作引起的快速暂态过电压（VFTO）进行了研究，分析了残余电荷对主变上过电压的影响，比较了分合闸电阻对频率，幅值，陡度以及加装避雷器对主变的影响，结果表明泄放残余电荷能够有效地限制过电压，当分合闸电阻R〉100Ω能使幅值和陡度降至1．25p．u以下，加装避雷器只能限制幅值，对其陡度基本无影响，其结果可为实际工程提供理论依据。     

特快速暂态下变压器线圈的集中参数混合模型

由于GIS中开关的投切产生的特快速暂态过电压对变压器的绝缘危害极大,为了有效仿真线圈中的快速暂态过程,提出了一种以单匝中并联导线为单元支路和以2段线匝为单元支路相结合的集中参数混合线圈模型．基于准静态电磁场,拓扑网路的大小和参数与变压器的结构和特性有关,网络中的电感和电容等参数是无源和线性的,但它们与传播电磁波的介质有内在的联系．给出了参数的计算方法．通过对模型的仿真分析得到了线匝之间的电位梯度,为线圈的绝缘设计提供了依据．     

快速暂态过电压测试技术的研究

本文对气体绝缘配电站(GIS)中出现的快速暂态过电压提出了一种新的测量系统——电容探头-阻抗变换器测量系统。文中对电容探头,阻抗变换器的特性进行了系统的试验表述,并对测量电缆的补偿进行了计算,给出了决定最佳补偿参数的方法。     

GIS中VFTO测量方法初探

随着我国电力工业的高速发展和电压等级的不断提高,气体绝缘变电站（GIS）在我国电力系统中得到越来越广泛的应用。随着GIS运行电压等级的提高,因隔离开关、接地开关和断路器的操作引起的快速暂态过电压（VFTO）将更加严重,对运行安全造成威胁。本文在简要介绍目前国内外几种VFTO测量方法的基础上,重点介绍了国内正在研制的一种新型VFTO测量系统--VFTO介质窗口式传感器。     

测量GIS中快速暂态过电压的微积分系统响应特性研究

研制了用于测量ＧＩＳ中快速暂态过电压（ＶＦＴＯ）的微积分（Ｄ／Ｉ）系统。为了验证Ｄ／Ｉ系统实测ＶＦＴＯ的响应特性，安装了一套波阻抗为５０Ω的同轴传输单元，其传输性能良好，不会引起波的畸变。方波响应试验表明，Ｄ／Ｉ系统的方波响应时间为２．５ｎｓ，满足ＶＦＴＯ对测量系统的要求。另外，测量电极的杂散参数和传输电缆对Ｄ／Ｉ系统响应特性有较大影响，应特别注意减小对地杂散电容的影响。     

不同变压器绕组模型对计算快速暂态过电压的影响分析

选取了等值入口电容模型、带损耗的高频模型以及以线饼为单元的等值回路模型,就快速暂态过电压(VFTO)对变压器内部绕组的影响进行了研究,同时研究了这3种不同模型对气体绝缘开关装置(GIS)内部元件处VFTO数值的影响,以及变压器绕组间VFTO的分布.计算结果表明,3种模型对GIS内VFTO的计算数值基本相同,影响VFTO数值的关键因素是变压器的等值入口电容值.     

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.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

橡胶颗粒沥青混合料低温抗裂性试验研究

以AC-13级配为基础,将橡胶颗粒代替部分集料掺入混合料中,以低温弯曲试验为评价方法对不同橡胶颗粒掺量下沥青混合料的低温抗裂性进行研究,并引入应变能密度值对混合料的低温抗裂性进行综合评价.试验结果表明:橡胶颗粒沥青混合料试件的破坏微应变均超过2 300,满足冬寒区的技术指标;无论是否掺加橡胶颗粒,随着温度的下降,沥青混合料破坏时的最大弯拉强度增大,弯拉应变降低,劲度模量增大;弯曲应变能密度在胶粒掺量为1%左右时具有较大的弯曲应变能密度值,此时橡胶颗粒沥青混合料具有较好的低温抗裂性.     

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-