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。     

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Kinect骨骼信息的三维轨迹特征稳定性研究

为了提高步态识别应用的广泛性,寻找稳定的人体动态特征,提出一种基于Kinect骨骼信息的步态特征提取方法,以验证骨骼点三维轨迹特征在步态识别中的稳定性。在分析深度相机Kinect工作原理的基础上,对Kinect有效范围进行测量并对其深度数据进行校准,通过18组实验对同一个体在不同行走模式、不同相机位姿下的人体骨骼点三维轨迹进行数据提取,并在固定相机位姿和行走模式的条件下对10组不同个体的行走数据进行提取,最后将同组骨骼点轨迹曲线在同一空间坐标系中进行绘制,同时使用动态时间规整算法(DTW)对实验个体骨骼点轨迹曲线相似度进行评价。实验结果表明,该特征在同一个体中表现出较好的稳定性,可用于步态识别的同一认定。     

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。     

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     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with