加权一阶局域法在电力系统短期负荷预测中的应用

在混沌时间序列的基础上提出加权一阶局域法, 并将其应用于电力系统历史负荷数据序列进行预测. 通过对华东某电网实际负荷数据进行预测, 结果令人满意.     

短期负荷多变量混沌时间序列正则化回归局域预测方法

为提高短期负荷预测的精度,提出了多变量混沌时间序列正则化回归局域预测方法.选取对负荷影响程度最大的实感温度因素,构建了多变量时间序列.首先采用互信息法和最小预测误差法确定出时间序列延迟和嵌入维数,并依据确定的重构参数进行短期负荷多变量时间序列的相空间重构,针对局域预测法中邻近点个数少而不能满足最小二乘估计条件的问题,提出了基于正则化回归的多变量时间序列混沌局部预测模型.通过重庆某地区电力系统短期负荷预测的计算实例表明,该方法具有较强的自适应能力和较好的预测效果.     

混沌时间序列预测的建模与仿真研究

研究混沌时间序列预测准确性问题,由于混沌时间序列具有混沌性和非线性,传统时间序列预测方法不能准确将混沌时间序列变化规律计算出来,导致预测精度低.为了提高混沌时间序列预测的精度,提出一种改进支持向量机的混沌时间序列预测方法(PSO-LSSVM).PSO-LSSVM采用相空间重构对混沌时间序列进行重构,去除其混沌性,用支持向量机对非线性进行预测,并采用粒子群算法对支持向量机参数进行优化,对经典混沌时间序列Mackey-Glass最优模型进行仿真测试.仿真结果表明,PSO-LSSVM加快了预测速度,提高了预测精度,在混沌时间序列预测中具有很好的应用价值.     

基于混沌时间序列的城网饱和负荷预测方法

由于饱和负荷预测的时间跨度大、影响因素多,易导致所得结果偏差较大.为此,基于混沌时间序列设计了一种新的城网饱和负荷预测方法.在相空间的基础上,计算负荷时间序列的饱和关联维数,选取重构相空间内的最佳嵌入维数,并定量分析负荷时间序列的混沌特性;然后确定饱和负荷的增长趋势,通过判断指标衡量饱和负荷预测值,并收集城网历史供电信息,获取最大负荷历史数据;运用趋势外推法建立函数模型,利用中值处理法获得模型预测平均值,选取实际负荷时间序列数据 对其精度实施检验,最终完成对城网饱和负荷的预测.实验结果表明:该方法预测结果较为准确,可消耗较短的时间达到较高的预测精度,具有良好的实用价值和应用前景.     

基于小波支持向量机的混沌时序预测算法

研究混沌时间序列预测问题,混沌时间序列是一种特殊时间序列,具有高度非线性、混沌性和时变性,传统预测方法精度低。为了提高混沌时间序列预测的精度,提出一种采用小波支持向量机的混沌时间序列预测算法。首先采用相空重构对混沌时间序列进行重构,捕捉时间序列变化轨迹,然后采用小波支持向量机对非线性、混沌性变化规律进行预测,最后采用Lorenz混沌时间序列进行仿真。结果表明,相对于传统预测方法,小波支持向量机提高了混沌时间序列预测精度,降低预测误差,为混沌时间序列提供了一种有效的准确预测途径。     

Gaussian小波SVM及其混沌时间序列预测

为了提高混沌时间序列的预测精度,针对小波有利于信号细微特征提取的优点,结合小波技术和SVM的核函数方法,提出基于Gaussian小波SVM的混沌时间序列预测模型。证明了偶数阶Gaussian小波函数满足SVM平移不变核条件,并构建相应的Gaussian小波SVM。对混沌时间序列进行相空间重构,将重构相空间中的向量作为SVM的输入参量。用Gaussian小波SVM与常用的径向基SVM及Morlet小泼SVM进行对比实验,通过对Chen’s混沌时间序列和负荷混沌时间序列的预测,结果表明,Gaussian小波SVM的效果比其他两种SVM更好。     

Gaussian小波SVM及其混沌时间序列预测

为了提高混沌时间序列的预测精度,针对小波有利于信号细微特征提取的优点,结合小波技术和SVM的核函数方法,提出基于Gaussian小波SVM的混沌时间序列预测模型.证明了偶数阶Ganssian小波函数满足SVM平移不变核条件,并构建相应的Gaussian小波SVM.时混沌时间序列进行相空间重构,将重构相空间中的向量作为SVM的输入参量.用Ganssian小波SVM与常用的径向基SVM及Morlet小渡SVM进行对比实验,通过对Chen's混沌时间序列和负荷混沌时间序列的预测,结果表明,Ganssian小波SVM的效果比其他两种SVM更好.     

最小二乘支持向量机在混沌时间序列中的应用

针对混沌时间序列存在噪声和不稳定性问题,混沌时间序列预测是当前的一个热点问题.根据当前预测方法预测精度低的难题,提出一种优化的混沌时间序列预测方法(GA_LSSVM).GA_LSSVM首先采用相空间重构对时间序列样本进行重构,采用遗传算法对最小二乘支持向量机参数进行优化,得到混沌时间序列的最优预测模型,最后以经典时间序列Lorenz数据对最优模型进行仿真测试和分析.实验结果表明,GA_LSSVM比神经网络的预测精度高.GA_LSSVM方法是一种可行的、有效的混沌时间序列预测算法,在混沌时间序列具有广泛的应用前景,可为应用提供科学依据.     

非线性时间序列混沌特性分析及短期预测

为提高非线性时间序列预测的准确性和可靠性,采用基于混沌理论的方法对时间序列进行分析和预测.在研究关联维数和最大Lyapunov指数算法基础上,利用关联维数和最大Lyapunov指数判定时间序列的混沌特性,根据混沌特性参数建立预测模型,并对非线性时间序列进行预测.以上海证券交易所股票价格指数时间序列为实例验证预测模型,研究结果表明,基于混沌特性参数建立的预测模型具有较好的预测能力和预测精度,证明用该方法预测非线性时间序列具有可行性.     

基于回声状态网络的多变量预测模型的研究

考虑单变量在混沌时间序列预测中的不足,文章利用多变量模型进行混沌时间序列的预测。针对多变量预测过程中的维数过高问题,文章结合主元分析理论(PCA)和回声状态网络(ESN),构建了基于PCA和ESN的多变量混沌时间序列预测模型,将PCA降维后的时间序列数据输入ESN网络进行预测分析。论文对由Lorenz动态方程生成的三变量混沌时间序列进行了仿真实验,结果表明该模型有效地提高了预测的精度和预测的效率,是一种有效的混沌时间序列预测方法。     

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.     

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~~     

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