基于LMI的μ方法及其在电力系统中的应用

提出了一个新的基于linear matrix inequality(LMI)的混合结构奇异值(μ)分析与综合 方法,通过采用S-过程,将Robust LMI形式的判据简化,得到了可验证的基于LMI的μ分析综 合判据.该判据是基于状态空间描述的,从而消除了频率扫描过程和频率响应曲线拟合过程并 具有更好的数值性态.将该方法应用于典型电力系统励磁控制的鲁棒稳定性分析和鲁棒控制器 的设计中,数值仿真结果同现有AVR+PSS控制器的结果所做比较表明该方法的有效性.     

基于局部超平面的流形奇异值点去除算法

局部线性嵌入算法通常用于高维流形数据降维,具有结构简单、不易陷入局部极小值、能保持局部几何结构不变的特点,但它对噪声和干扰奇异值点非常敏感。为此,提出基于局部超平面的流形奇异值点去除算法,将样本点的邻域投影到超平面空间,使干扰奇异值点投影远离流形样本点投影,而流形样本点投影则表现为聚集特征,同时找出邻域中所有远离聚集中心的样本点作为干扰奇异值点。仿真实验结果验证了该算法的正确性和有效性。     

基于改进的局部保持投影算法的人脸识别

局部保持投影算法是基于流形的学习方法,在人脸识别过程中容易遇到奇异值问题,为此提出一种利用奇异值分解的方法。在模型中,样本数据被投影到一个非奇异正交矩阵中,解决了奇异值问题;然后再根据局部保持投影算法求出新样本空间的低维投影子空间。将训练样本和测试样本分别投影到低维子空间中,再利用最近邻分类器进行分类识别。在ORL人脸数据库中,采用了一系列的实验来对比该算法与传统局部保持投影算法和主成分分析算法的识别效果。实验结果验证了改进的局部保持投影算法在人脸识别的有效性。     

复结构奇异值的几何解释及其计算:两块情形

应用几何方法给出两块情形复结构奇异值的几何解释,并提出一种简单迭代计算方法.该 方法求的是结构奇异值的真值而非其某一上界或下界.     

基于规范变量分析的子空间辨识方法及应用

深入研究和推广了一种基于规范变量分析(CVA)的子空间辨识方法,并引入一种新的Akaike信息判据来获得系统阶次,求解过程简单,结果精确。由于此法直接由数据确定系统状态,避免了预先参数化;在计算上,主要依赖于奇异值分解(SVD),也不会遇到与传统方法有关的数值困难。仿真研究结果表明,引入新的系统阶次求解方法后能很精确地辨识出系统模型,具有十分广阔的应用前景。     

有色噪声背景下的正交子空间辨识

针对传统子空间辨识中存在的有色噪声干扰问题,本文提出一种正交子空间辨识方法.首先,根据子空间辨识算法机制构建含有色噪声的扩展状态空间模型.然后,结合有色噪声的相关性分析,研究了传统子空间辨识方法的有偏性问题,并重新设计了投影向量和正交投影方式,用以消除有色噪声干扰.最后,对投影后的数据矩阵进行奇异值分解,获取广义能观测矩阵,进而求得系统的状态空间模型参数.仿真结果表明该方法在有色噪声干扰下是一致无偏的,并且具有渐进二阶统计特性.结合陀螺仪的具体实验结果表明,该算法在实际应用中具有比传统子空间辨识法更高的辨识精度.     

细分法求解点投影问题时的剪枝算法

点到NURBS曲线/曲面的投影是CAD中的基础问题.为了避免数值迭代法陷入局部最优,通常把曲线/曲面细分为多段.文中提出排除无用曲线段/曲面片的剪枝算法,以提高细分求解投影的运行效率.在投影算法中将曲线/曲面递归细分,分别计算测试点到各个曲线段/曲面片的投影值;在递归过程中,对当前曲线段/曲面片计算测试点到控制点凸包距离的近似距离,如果该距离大于投影距离上界值,根据NURBS曲线/曲面的凸包性,测试点到当前曲线段/曲面片的投影距离也一定大于上界值,无需计算投影结果,直接排除该曲线/曲面.最后通过测试实例验证了该算法的有效性.     

奇异摄动系统极限解存在的代数判据

讨论了线性奇异摄动系统广义状态解当ε趋于零时在广义函数空间上的收敛性问题.在已有结论的基础上,得到了奇异摄动系统广义状态解收敛的代数判据,该判据简化了对奇异摄动系统广义状态解收敛性的判别,为系统控制器设计提供了一种代数条件.     

基于线性投影的代数空间降维分析

主成分分析和奇异值分解都可以用于代数空间降维的线性投影分析，该文详细分析了这两种代数方法并给出了用于代数空间降维分析时二者之间的联系，并得到了在正定的实对称矩阵条件下主成分分析和奇异值分解是等价的这一结论。     

基于结构保留投影的镜头边界检测

提出了一种基于结构保留投影的镜头边界检测方法。为了提取更具判别力的视频特征,提出了结构保留投影方法,利用流形结构信息而非空间结构信息构建连接矩阵,利用QR分解方法解决了结构保留投影的奇异值问题;采用支持向量机检测镜头边界。实验结果表明该方法具有很好的检测效果。     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

View-based model-driven architecture for enhancing maintainability of data access services

In modern service-oriented architectures, database access is done by a special type of services, the so-called data access services (DAS). Though, particularly in data-intensive applications, using and developing DAS are very common today, the link between the DAS and their implementation, e.g. a layer of data access objects (DAOs) encapsulating the database queries, still is not sufficiently elaborated, yet. As a result, as the number of DAS grows, finding the desired DAS for reuse and/or associated documentation can become an impossible task. In this paper we focus on bridging this gap between the DAS and their implementation by presenting a view-based, model-driven data access architecture (VMDA) managing models of the DAS, DAOs and database queries in a queryable manner. Our models support tailored views of different stakeholders and are scalable with all types of DAS implementations. In this paper we show that our view-based and model driven architecture approach can enhance software development productivity and maintainability by improving DAS documentation. Moreover, our VMDA opens a wide range of applications such as evaluating DAS usage for DAS performance optimization. Furthermore, we provide tool support and illustrate the applicability of our VMDA in a large-scale case study. Finally, we quantitatively prove that our approach performs with acceptable response times.     

A pragmatic multi-method investigation of discrepant technological events: Coping,attributions, and ‘accidental’ learning

Discrepant technological events or situations that entail a problem, a misunderstanding or a difficulty with the Information Technology (IT) being employed, are common in the workplace, and can lead to frustration and avoidance behaviors. Little is known, however, about how individuals cope with these events. This paper examines these events by using a multi-method pragmatic approach informed by coping theory. The results of two studies – a critical incident study and an experiment – serve to build and test, respectively, a theoretical model that posits that individuals use a variety of strategies when dealing with these events: they experience negative emotions, make external attributions, and adopt engagement coping strategies directed at solving the event, eventually switching to a disengagement coping strategy when they feel they have no control over the situation. Furthermore, users’ efforts may result in ‘accidental’ learning as they try to overcome the discrepant IT events through engagement coping. The paper ends with a discussion of the results in light of existing literature, future opportunities for research, and implications for practice.     

The Distributed Time-Triggered Simulation Scheme: Core Principles and Supporting Execution Engine

Distributed real-time simulation is a young technology field but its practice is under increasing demands. In recent years the author and his collaborators have been establishing a new approach called the distributed time-triggered simulation (DTS) scheme which is conceptually simple and easy to use but widely applicable. The concept was initiated in the course of developing a new-generation object-oriented real-time programming scheme called the time-triggered message-triggered object (TMO) programming scheme. Some fundamental issues inherent in distributed real-time simulation that were learned during recent experimental studies are discussed along with some approaches for resolving the issues. An execution engine developed to support both the TMOs engaged in control computation and the TMOs engaged in DTS is also discussed along with its possible extensions that will enable significantly larger-scale DTSs.     

Software-Konfigurationsmanagement in großen Softwareprojekten

Zusammenfassung Mit zunehmender Größe der Softwaresysteme verschärfen sich die für die Software-Herstellung typischen Probleme: Beherrschen großer Objektmengen, Erhalten der Systemkonsistenz, Kontrolle der ständigen Änderungseinflüsse und Gewährleisten einer langen Lebensdauer. Die Disziplin Konfigurationsmanagement bildet den methodischen Ansatz, diese Probleme besser zu beherrschen. Software-Konfigurationsmanagement faßt die Herstellung von Softwaresystemen als eine Abfolge von kontrollierten Änderungen an gesicherten Zwischen- und Endergebnissen auf. Dargestellt werden die Objekte und Funktionen des Software-Konfigurationsmanagements sowie die hierfür in großen Software-Projekten benötigten Methoden, Instanzen und Hilfsmittel.     

Call for Papers The 6^th International Conference on Grid and Cooperative Computing

Recent years have seen rapid advances in various grid-related technologies, middleware, and applications. The GCC conference has become one of the largest scientific events worldwide in grid and cooperative computing. The 6th international conference on grid and cooperative computing (GCC2007) Sponsored by China Computer Federation (CCF),Institute of Computing Technology, Chinese Academy of Sciences (ICT) and Xinjiang University ,and in Cooperation with IEEE Computer Soceity ,is to be held from August 16 to 18, 2007 in Urumchi, Xinjiang, China.     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and     

Editorial:Brain-machine interface(BMI) and cyborg intelligence

正Brain-machine interfaces(BMIs)aim at building a direct communication pathway between the brain and an external device,and represent an area of research where significant progress has been made during the past decade.Based on BMIs,mind information can be read out by neural signals to control     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate     

SCIENCE CHINA Information Sciences SUBJECT INDEX TO VOLUME 57(2014)

正~~