采样频率对强跟踪滤波器算法故障测距的误差影响

当输电线路发生故障时,要快速、准确、可靠地对故障进行定位,从而提出了一种基于强跟踪滤波器理论的故障测距方法.在搭建的模型中,基于强跟踪滤波器算法原理,不同的采样频率下,故障测距的误差是不同的,结果与解微分方程法测得结果接近,说明建立的测距模型是准确的.在PSCAD/EMTDC软件下,对强跟踪滤波算法进行仿真分析,仿真结果表明,该算法是一种简单的递推算法,原理简单,不需要求解复杂的数学方程,能更好、更快的消除噪声,使信号收敛快,实施性好,鲁棒性好.本文主要研究不同采样频率仿真下误差的不同,为基于强跟踪滤波器算法的电力系统故障测距装置提供了理论依据.     

输电线路阻抗测距法和单端行波测距法的对比仿真分析

简述了输电线路的故障测距算法,着重论述了阻抗法和单端行波法的测距原理．在ATPDraw环境下,建立了输电线路仿真模型,并在不同参数条件下和线路发生不同故障类型时,分别用阻抗法和单端行波法对线路故障距离进行仿真计算．仿真计算结果表明,单端行波法具有更高的测量精度和可靠性．     

利用高斯最小频移键控(GMSK)调制的遥测和测距技术

分析和仿真了一种利用GMSK调制方式同时传输遥测信号和伪码测距信号的技术。利用GMSK调制方式同时传输遥测信号和伪码测距信号,可以有效地提高频谱利用率。分析了方案中遥测信号和测距信号的各种解调算法,并说明了各种算法的实现途径。通过分析和仿真,得到了各种算法的遥测和测距性能及相应的测距精度。仿真结果表明,在设置的仿真条件下,方案的性能和测距精度能够达到工程需求。     

利用GMSK调制的遥测和测距技术

分析和仿真了一种利用GMSK调制方式同时传输遥测信号和伪码测距信号的技术。利用GMSK调制方式同时传输遥测信号和伪码测距信号,可以有效地提高频谱利用率。本文分析了方案中遥测信号和测距信号的各种解调算法,并说明了各种算法的实现途径。通过分析和仿真,得到了各种算法的遥测和测距性能及相应的测距精度。仿真结果表明,在设置的仿真条件下,方案的性能和测距精度能够达到工程需求。     

狼群算法优化BP神经网络的电缆故障测距算法

故障信号频率分量的提取精度与故障测距的精度有很大的关系.针对这一问题,采用向后预测Prony算法提取故障电压信号的固有频率作为样本,应用狼群算法优化BP神经网络的结构,并对其进行训练,改善了易产生多个局部极小值的缺陷,提高了网络的训练效率和收敛速度,使得测距更加精确.通过ATP/Matlab仿真结果表明,该算法具有良好的鲁棒性和精确性.     

非直接接地系统两相接地故障的单端测距

提出了一种输电线路中性点非直接接地系统双相对地故障的准确测距方法。该算法利用故障网络与零序网络建立故障测距模型,利用单端信号有效地消除了负荷潮流和故障接地电阻对故障测距精度的影响,并可以自动地确定故障线路。仿真结果表明,在接地故障情况下该算法具有准确有效的特点。     

基于GIE-DOL的地面网络化弹药自定位算法

为解决传统自定位算法在精度和复杂度上不能适应地面网络化弹药的问题,研究了三边测量法的影响因素. 推导误差公式,明确了误差由节点几何关系和测距误差共同影响. 提出几何影响因子和定位距离偏差描述其影响程度,并对信标节点组合进行评价和筛选,加权计算坐标. 仿真结果表明,该算法最小化了不利因素的影响,有效地提高了定位精度,对测距误差具有较好的鲁棒性,同时该算法在弹药节点分布密集和松散的条件下均有较好的效果.      

基于改进型粒子群优化的节点自定位算法

为了提高测距误差影响下无线传感器网络节点自定位精度,提出一种基于距离的节点自定位新算法.对混沌搜索与粒子群优化进行算法融合,给出一种改进型粒子群优化算法,将其应用于节点自定位.新算法利用未知节点与信标节点之间的距离信息,通过改进型粒子群优化算法获取未知节点的位置.仿真结果表明,改进型粒子群优化算法对两种标准测试函数的搜索结果优于一般的粒子群优化算法.在测距误差和信标节点数量相同的条件下,相对于最小二乘估计法,新算法在各个测距误差级上的定位精度更高,其定位误差随测距误差增大而上升的趋势更缓慢.新算法具有更好的鲁棒性,适用于测距误差较大、信标节点数量较少的情况.     

基于小波变换和行波法的电缆故障测距方法研究

本文采用搜索模极大值的方法,进而实现故障的精确测距。通过MATLAB仿真平台,建立了电力电缆故障系统的仿真模型,得出电缆故障波形图。不同位置的不同故障的仿真数据相对误差均小于4%,验证了该方法的可行性和准确性。同时提出并推导一种不包含波速 的测距公式,使得在计算故障距离从理论上摆脱了波速对测距结果的影响。     

基于分布参数模型的同杆双回输电线路故障测距

基于线路的分布参数模型,并且利用线路两端工频电气量和相模变换,提出了在模域中进行故障测距的算法.该算法不受系统阻抗和过渡电阻的影响,并且消除了双回线间耦合的影响,可用于单回线故障和跨线故障的测距.该算法原理简单,求解方便,仿真结果表明,算法具有较高的精度,最大测距误差小于0.5%,能够满足工程要求.     

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.     

A computer generator for randomly layered structures

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

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。     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with     

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     

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

正~~     

An on-line scaling method for improving scalability of a database cluster

The explosive growth of the Internet and database applications has driven database to be more scalable and available, and able to support on-line scaling without interrupting service. To support more client's queries without downtime and degrading the response time, more nodes have to be scaled up while the database is running. This paper presents the overview of scalable and available database that satisfies the above characteristics. And we propose a novel on-line scaling method. Our method improves the existing on-line scaling method for fast response time and higher throughputs. Our proposed method reduces unnecessary network use, i.e. , we decrease the number of data copy by reusing the backup data. Also, our on-line scaling operation can be processed parallel by selecting adequate nodes as new node. Our performance study shows that our method results in significant reduction in data copy time.     

An improved R-tree based on childnode''s probability

R-Tree is a good structure for spatial searching. But in this indexing structure,either the sequence of nodes in the same level or sequence of traveling these nodes when queries are made is random. Since the possibility that the object appears in different MBR which have the same parents node is different, if we make the subnode who has the most possibility be traveled first, the time cost will be decreased in most of the cases. In some case, the possibility of a point belong to a rectangle will shows direct proportion with the size of the rectangle. But this conclusion is based on an assumption that the objects are symmetrically distributing in the area and this assumption is not always coming into existence. Now we found a more direct parameter to scale the possibility and made a little change on the structure of R-tree, to increase the possibility of founding the satisfying answer in the front sub trees. We names this structure probability based arranged R-tree (PBAR-tree).     

Integrating GIS Web services based on mediating architecture

The geographic information service is enabled by the advancements in general Web service technology and the focused efforts of the OGC in defining XML-based Web GIS service. Based on these models, this paper addresses the issue of services chaining,the process of combining or pipelining results from several interoperable GIS Web Services to create a customized solution. This paper presents a mediated chaining architecture in which a specific service takes responsibility for performing the process that describes a service chain. We designed the Spatial Information Process Language (SIPL) for dynamic modeling and describing the service chain, also a prototype of the Spatial Information Process Execution Engine (SIPEE) is implemented for executing processes written in SIPL. Discussion of measures to improve the functionality and performance of such system will be included.     

Tracking data management using topology of moving object database system for moving object constrained trajectory in LBS application

Advances in wireless technologies and positioning technologies and spread of wireless devices, an interest in LBS (Location Based Service) is arising. To provide location based service, tracking data should have been stored in moving object database management system (called MODBMS) with proper policies and managed efficiently. So the methods which acquire the location information at regular time intervals then, store and manage have been studied. In this paper, we suggest tracking data management techniques using topology that is corresponding to the moving path of moving object. In our techniques, we update the MODBMS when moving object arrived at a street intersection or a curved road which is represented as the node in topology and predict the location at past and future with attribute of topology and linear function. In this technique, location data that are corresponding to the node in topology are stored, thus reduce the number of update and amount of data. Also in case predicting the location,because topology are used as well as existing location information, accuracy for prediction is increased than applying linear function or spline function.