基于知识发现和分层ELM的暂态失稳模式辨识

为了有效辨识电力系统暂态失稳后发电机的动态行为,以失稳后的功角数据为输入特征信息,提出一种基于知识发现和分层极限学习机(ELM)的失稳模式辨识方法。首先利用ELM快速辨识系统暂态不稳定的功角样本。为了充分利用不稳定样本自身结构来挖掘关键信息,引入知识发现算法KODAMA以获取发电机的不稳定动态行为模式,构建失稳功角模态集。然后,根据所得模态数据集,为提高不稳定模式辨识的准确性,设计了分层ELM的辨识策略以辨识发电机的失稳模式。最后,在Nordic系统中验证所提方法的有效性,测试结果表明提出的辨识方法能够准确地辨识失稳模式,且在保证尽可能高精度的前提下,具有相对快速的评估速度。     

基于轨迹灵敏度的暂态稳定预防控制方法

预防控制对提高稳定性及维持系统安全运行有重要意义.基于电力系统角半径的概念,对角半径及其变化速度与暂态稳定性的关系进行了深入研究,在此基础上定义了一种新型暂态稳定性能指标.通过轨迹灵敏度仿真,计算稳定指标对各发电机有功输出的梯度近似值,将预防控制问题转化为以发电机有功输出为控制量的非线性规划问题.该方法易于求解,且不受元件模型的限制,适用于各种复杂失稳模式.对10机新英格兰典型电力系统的分析结果表明,该方法快速、可靠,能够在确保系统安全的前提下实现经济性最优.     

基于扩展等面积准则的电力系统快速稳定判据

随着电力系统规模的不断扩大,系统失稳的频率不断增加,电力系统稳定的判别及相应的控制策略对防止事故蔓延导致大规模停电甚为关键。扩展等面积准则(extended equal area criterion,EEAC)将等面积法则扩展到多机。不仅能判断系统稳定;还能给出系统的稳定裕度,已经在世界范围内得到广泛应用。相量量测装置(phasor measurment unit,PMU)虽然可以实测受扰轨迹,但实测数据的的精度还相对较低,而且还没有达到全网普及的程度。将SBS(step by step,逐步积分法)与EEAC相结合提出了一种实用的稳定判别方法,一方面不需要精确掌握全网各机的摇摆曲线曲线,节省了时间;另一方面不断对分群进行校正,确保准确得到临界分群,进而保证判定结果的准确性。IEEE10机39节点的算例验证了方法的有效性。     

基于机组虚拟分解－聚合的直接暂态稳定分析新方法

提出了一种基于机组虚拟分解－聚合的直接暂态稳定分析新方法，该法根据系统受扰后的机组运行轨迹进行机组虚拟分解和聚合，不需识别临界机群，而能可靠获得单机无穷大等值系统参数。该法可适应复杂操作序列，如继电保护相继动作、重合闸及切机等，并可适应多机群失稳模式。在经典模型下，其精度和逐步积分法（ＳＢＳ法）相一致，并仍保持快捷的分析速度，具有良好的在线应用前景。     

转子绝对动能增量及其在失稳模式判别中的应用

研究了大扰动下复杂电力系统失稳模式的判别指标。针对暂态能量函数法使用的势能概念在物理意义上的疑问,从发电机原始转子运动方程和经典转子运动方程出发,讨论了转子不平衡功率对时间积分的物理意义,分析了它们同暂态稳定分析中使用的势能概念的关系,在此基础上提出了相对动能和绝对动能的概念。根据发电机绝对动能增量大的机组最有可能率先失步的事实,提出了以绝对动能增量为指标进行电力系统失稳模式判别的方法,并通过对实际系统的仿真计算验证了方法的可行性。     

基于扩展等面积准则的快速电力系统稳定判据

随着电力系统规模的不断扩大,系统失稳的频率不断增加,电力系统稳定的判别及相应的控制策略对防止事故蔓延导致大规模停电甚为关键.扩展等面积准则(extended equal area criterion,EEAC)将等面积法则扩展到多机.不仅能判断系统稳定;还能给出系统的稳定裕度,已经在世界范围内得到广泛应用.相量量测装置(phasor measurment unit,PMU)虽然可以实测受扰轨迹,但实测数据的的精度还相对较低,而且还没有达到全网普及的程度.将SBS(step by step,逐步积分法)与EEAC相结合提出了一种实用的稳定判别方法,一方面不需要精确掌握全网各机的摇摆益线曲线,节省了时间;另一方面不断对分群进行校正,确保准确得到临界分群,进而保证判定结果的准确性.IEEE10机39节点的算例验证了方法的有效性.     

PO反应混沌特性的理论研究

采用非线性稳定理论的分析方法 ,对peroxidase oxidase反应 (PO反应 )所呈现的混沌态进行了理论研究 .通过计算PO反应系统的最大Lyapunov指数 ,判定该系统失稳后的演化模式为混沌态 ,数值模拟反应物O2 浓度随时间变化的混沌曲线与实验测定的混沌曲线相吻合 .     

基于运动模式的点源目标识别算法的研究

目前常用的点源运动目标识别方法并未考虑运动目标自身运动规律,难以识别目标属性,降低了目标识别的准确性。本文提出三点Hermite插值轨迹匹配识别方法,用以识别点源目标运动模式。该方法首先根据已知目标自身运动规律,建立目标运动轨迹全方位投影曲线标准库;然后,采用三次Hermite插值曲率逼近的方法,获得点源目标实际运动轨迹;最后,利用Hansdorff距离匹配实际目标运动轨迹与曲线标准库轨迹,并根据匹配结果识别点源目标。     

移动磁场作用下的通电导线的非线性动力学分析

研究输电线在磁场中谐扰力作用下的主共振问题,应用动力学方法建立磁场中受谐扰力作用输电线的非线性振动。根据非线性振动的多尺度解法,得到了系统满足主共振情况的近似解,并对其进行数值计算。分析磁场变化、外部激励、调谐值、阻尼等对系统的响应。得到系统失稳的临界磁场强度,指出力幅响应曲线存在跳跃现象。     

移动磁场作用下的通电导线的非线性动力学分析

研究输电线在磁场中谐扰力作用下的主共振问题,应用动力学方法建立磁场中受谐扰力作用输电线的非线性振动.根据非线性振动的多尺度解法,得到了系统满足主共振情况的近似解,并对其进行数值计算.分析磁场变化、外部激励、调谐值、阻尼等对系统的响应.得到系统失稳的临界磁场强度,指出力幅响应曲线存在跳跃现象.     

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.     

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.     

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.