电力变压器局部放电特高频信号外部传播特性研究

针对变压器箱体的接缝处可以衍射出局部放电特高频(UHF)电磁波信号的现象,在分析变压器箱体接缝对局部放电特高频电磁波传播影响的基础上,探讨了接收天线外部检测特高频信号的可行性,并通过实验研究了局部放电特高频电磁波的外传播特性,通过对信号进行小波包分析,比较了外部接收和内部接收信号的差异.结果表明,特高频电磁波可以透过变压器箱体接缝衍射出来,且频两者谱能量分布并非完全一致,外部检测到的特高频信号距离接缝的远近具有不同的表现形式,强度随着变压器箱体缝宽增大而增大.研究工作为变压器局部放电外部检测提供了理论指导.     

GIS超高频局部放电在线监测技术应用研究

超高频(UHF)局部放电检测技术是目前国际上对气体绝缘全封闭组合电器(GIS)类设备普遍采用的状态监测技术,具有灵敏度高、抗干扰性好等特点。本文介绍了一个基于超高频局放检测技术的GIS设备在线监测系统,其中运用UHF传感器捕捉GIS内部局部放电信号,经过在线监测系统对捕捉信号进行信号采集、检测、运算和分类,结合人工智能专家判别系统,来分析GIS设备状态与故障特征。实际现场应用结果表明了该系统的有效性。     

GIS局放超高频在线监测系统研制

利用超高频微带贴片天线传感器和超高频滤波放大器,实现了局部放电信号的采集、提取、调理和传输.采用LabVIEW图形化语言的虚拟仪器技术实现了对气体绝缘组合电器(GIS)设备局部放电信号的定时循环检测、信号处理、数据分析、缺陷类型模式识别、监测数据查询和绝缘状况初步评估等功能.该系统已在重庆市某220 kV级GIS变电站成功运行,试验运行结果表明,采用虚拟仪器技术的GIS局部放电超高频在线检测系统能实现GIS局部放电超高频检测.     

新型宽波束圆极化UHF终端监测天线设计

本文设计了一种UHF频段宽波束圆极化天线。天线辐射振子为十字交叉阵子形式且采用同轴馈电方式,反射器也采用十字振子取代常用的金属板。这样既可以提高天线增益,又可以有效地降低风载利于实际工程应用。软件仿真结果表明,该天线在工作频带内电压驻波比小于2.0,增益大于5.0dB,具有120°以上的方向图波瓣宽度并且圆极化特性良好。同时,该天线具有小型化、轻型化和低成本的优点,其可以作为高速公路收费系统的终端监测天线。     

一种低轮廓超宽带天线的设计与分析

以盘锥天线为基础,通过调整底盘尺寸、上锥张角的大小、馈电结构等方法,研究盘锥天线的输入和辐射特性随天线结构的变化关系,从而设计主辐射方向在水平面内的低轮廓超宽带天线。数值模拟结果表明,该天线具有很宽的工作频带和很好的时域特性,且具有较低的轮廓,可以应用在便携式设备中。     

基于射频感应技术的相位传感器设计

设计了一种局部放电在线监测用工频相位传感器,该传感器基于射频感应的原理,采用定制的工频感应天线和信号滤波放大模块。设计的传感器在实验室和变电站现场经过试验,可以较好地感应出工频信号,频率相位一致性好。     

检测高压电缆附件局部放电用超高频蝶形天线的研究

针对电缆附件的结构及附件内部易发生绝缘故障导致局部放电的特点,设计了用于电缆附件局部放电信号检测的内置超高频超宽带蝶形天线传感器.仿真和实测表明,该蝶形天线的有效工作频带为350～585 MHz.模拟实验表明该天线传感器灵敏度高、性能优越,能在有效频率范围内检测到局部放电信号,可以用于电缆附件局部放电超高频信号的检测.     

多天线UHF RFID系统的性能分析

超高频(UHF)射频识别(RFID)系统的性能受到多径信道的制约,为提高UHF RFID系统的可靠性,文中针对前向信道和后向信道都为莱斯分布的UHF RFID系统,给出了最大比合并(MRC)准则下系统信噪比的概率分布,导出了系统中断概率和误码率的理论表达式,并开发了多天线UHF RFID读写器的原型机,通过数值仿真和实际测试考察接收天线数、莱斯因子对系统性能的影响.实验结果表明,多天线技术能够有效地提高UHF RFID系统的性能,并且接收天线越多,系统的中断概率和误码率越低.     

LTE上行系统循环延迟分集接收方案的设计

在长期演进(LTE)系统上行链路中,基站因受限于发射天线数而无法获得较好的分集增益及系统性能.为此,文中提出了一种利用循环延迟叠加方法获得空间-多径满分集的接收方案.首先直接叠加不同接收天线上经过循环延迟的信号,然后做频域的最小均方误差线性均衡,最后进行逐个符号的检测.当不同接收天线选择合适的循环延迟时,文中方案能够以较低的解调复杂度获得系统的空间-多径满分集增益.仿真结果表明:相对于LTE系统上行链路中现有的接收端天线选择方案,文中方案不仅能够获得与天线选择相同的接收分集增益,而且能够获得比天线选择方案更高的编码增益,同时不增加系统的解调复杂度;在中断概率为10-3时,文中方案在瑞利信道下的系统性能提升2~4d B,在LTE扩展步行信道下的系统性能提升1.5 d B以上.     

电力变压器局部放电特高频信号外部传播特性研究

针对变压器箱体的接缝处可以衍射出局部放电特高频电磁波信号的现象,在分析变压器箱体接缝对局部放电特高频电磁波传播影响的基础上,探讨了接收天线外部检测特高频信号的可行性,并通过试验研究了局部放电特高频电磁波的外传播特性,通过对信号进行小波包分析,比较了外部接收和内部接收信号的差异．结果表明,特高频电磁波可以透过变压器箱体接缝衍射出来,且其频谱能量分布两者并非完全一致,外部检测到的特高频信号距离接缝的远近具有不同的表现形式,强度随着变压器箱体缝宽增大而增大．研究工作为变压器局部放电外部检测提供了理论指导．     

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.     

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.     

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.     

A computer generator for randomly layered structures

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

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.     

Jane Eyre——A Feminist In The 19th Century

In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.     

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-