零序电流分量改进的多判据融合故障选线定位

针对中性点不接地系统发生单相接地故障时选线可信度低的问题,提出了一种基于零序电流分量的多判据融合故障选线定位方法.该故障选线定位系统以差动选线原理为主,并结合多个暂态、稳态选线方法进行信息融合,优势互补,采用德尔菲法对选线方法进行评价,确定隶属度函数.通过模糊综合评价法对各选线法系统适应度进行隶属度优化,提高选线准确率.利用Matlab进行仿真实验,验证该选线定位方法的有效性和可靠性,仿真结果表明该方法选线定位准确可信度得到明显提高,可快速准确定位接地故障区域.     

多基因融合小电流接地故障选线方法

为解决目前单一判据选线方法中存在的可靠性低、选择性差和对电网结构适应能力低的技术问题,提出了基于遗传算法的小电流接地故障选线方法.算法通过对基于系统故障稳态参数选线的有功功率选线法和无功功率选线法,以及基于暂态参数的小波分析选线法的融合,获得高可靠性小电流接地故障选线判据.算法利用不同选线方法的基因概率进行编码形成初始种群,通过对种群基因的选择、交叉、变异运算,求得最优染色体串,译码后得到故障线路信息.从系统仿真结果看,该方法具有可靠性高、选择性好的特点,并且对不同结构的电网具有很好的适应能力.     

在生态环境保护视角下的风景区道路选线研究——以安徽省舒城县周瑜城风景区为例

将生态环境保护理念融入道路选线研究,是风景区生态环境可持续发展的前提和要求.以生态环境保护为目标的风景区道路选线需要考虑多个因素,而传统的通过避让敏感区的道路选线方案无法对这多个因素进行统一分析,因而可操作性不强.提出了一个在生态环境保护目标下,利用基于最小耗费距离模型的最优路径分析技术进行道路选线的方案,并以安徽省舒城县周瑜城风景区为例,进行了案例研究.研究结果表明,该道路选线方法可以按照选线方案,自动生成符合生态环境保护目标的最优路径.     

小波包在配电网单相接地故障选线中的应用

小波包分析在配电网单相接地选线中的应用是利用小波包变换提取配电网单相接地时有用的故障暂态信息,通过与非故障线路暂态信息比较实现选线.传统的配电网单相接地选线判据是基于故障稳态信息.本文通过对配电网单相接地故障暂态信息的分析,提出基于小波包变换提取故障暂态量作为故障选线判据的新方法,并通过MATLAB仿真验证了该方法的可行性与准确性.     

浅谈山区改建公路的选线与设计

山区改建公路在选线时需注意的几个主要问题,包括选线的原则,选线的方法及步骤,平面线形的设计及优化.     

多频带分析的配电网单相接地故障选线

针对多年来一直未得到根本解决的配电网单相接地故障选线问题, 在分析故障选线现状和基于小波包选线方法的基础上,提出了多频带分析的选线方法.根据各线路暂态零序电流信号小波包分解的能量分布情况,提出对各线路选择能量集中的特征频带或组合特征频带;并根据故障线路和非故障线路暂态零序电流大小关系原理,比较各条线路特征频带或组合特征频带的暂态零序电流的能量以确定故障线路.现场数据和大量的Matlab仿真试验结果表明:该选线方法可以准确、可靠地实现配电网单相故障的选线.     

智能漏电保护装置的设计与实现

根据故障选线的准确性和快速性对硬件系统的要求,提出了一种基于AVR单片机(ATmega128)的智能漏电保护装置,软件算法将多种选线方法结合在一起,运用模糊理论实现综合决策,得到综合智能选线结果.该平台充分利用AVR单片机的实时中断响应和快速的运算速度,很好地实现了综合智能选线算法.现场运行结果表明,该装置运行稳定,选线快速可靠,适应性强,具有良好的性价比,是小电流接地系统中一种实用的漏电保护装置.     

小电流接地选线装置的现状及发展趋势研究

应用小电流接地选线装置,当系统出现单相接地故障时,不会对系统电压对称性造成破坏,且故障电流较低,可以保护供电设备.当前,小电流选线装置多是在稳态分量法及谐波分量法原理的基础上发展而来,其选线判断依据十分单一,逐渐无法满足电力系统运行方式多变,接地故障类型复杂化及异常化发展的趋势.为此,提出小电流接地选线装置发展趋势的研究.结合多种新型智能选线判据,改进选线方案,提高选线准确性及技术水平是小电流接地选线装置未来发展的主要趋势.     

基于GA-BP神经网络的配电网故障选线方法研究

为了有效解决配电网故障选线的难题,对基于GA-BP神经网络的故障选线方法进行了研究,利用遗传算法优化BP神经网络,使BP神经网络克服易陷入局部极值和对初始权重敏感的缺点.将稳态和暂态下的各选线判据进行合理的信息融合,并通过GA-BP神经网络进行故障选线的训练和测试,从而得出故障线路.仿真分析结果验证了该选线方法的有效性.     

基于主频零序功率的配电网故障选线新方法

在复杂的小电流接地系统发生单相接地故障时,现有的利用相关性选线的方法有时因判据裕度不足而产生误判.针对裕度不足的问题,本文提出了基于主频零序功率的配电网故障选线方法,其以主频零序功率作为特征量来选线,计算出各馈线所对应的主频零序功率综合相关系数,其中故障线路综合相关系数小于零,而健全线路综合相关系数大于零.大量仿真结果表明,此方法在一定程度上提高了选线判据裕度和选线准确率,且不受合闸角和故障电阻的影响.     

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