求解带状线性方程组的一种并行算法

提出了一种在MIMD分布式存储环境下求解带状线性方程组的交替方向迭代并行算法。利用系数矩阵的结构特点分裂矩阵,使整个计算过程只在相邻处理机间通信两次。给出了系数矩阵分别为Hermite正定矩阵和M-矩阵时算法收敛的充分条件。最后,在HP rx2600集群系统上进行的数值计算表明,该算法与多分裂方法相比具有较高的加速比和并行效率。     

带状线性方程组的并行交替方向算法

提出了分布式存储环境下求解带状线性方程组的并行交替方向迭代算法。充分利用系数矩阵的结构特点,给出了在系数矩阵分别为Hermite正定矩阵和M-矩阵时算法的充分条件,并针对采用的分裂方式,讨论了参数的收敛范围,最后在HPrx2600集群系统上进行了数值计算,结果表明实算与理论相一致,算法简便可行且具有良好的并行性。     

求解块三对角方程组的一种并行策略

提出了一种在MIMD分布式存储环境下求解块三对角线性方程组的并行算法。基于Galerkin原理适当取基构造算法,使整个计算过程只在相邻处理机间通信两次,并给出了系数矩阵为对称正定矩阵时算法收敛的条件。在HP rx2600集群系统上进行的数值计算结果表明该算法与多分裂方法相比具有较高的加速比和并行效率。     

求解块三对角线性方程组的含参并行算法

提出了分布式环境下求解含有两个参数的矩阵分裂方式的一种交替方向迭代并行算法,通过引入两个参数并巧妙分解系数矩阵A得到新算法,从理论上给出了该算法收敛的两个充分条件,并讨论了参数的选择范围.基于局域网的MPI异构环境,在HP rx2600集群上进行了数值实验,并与多分裂方法比较.比较的结果表明,此算法是可行的,具有良好的并行效率.     

求解PageRank的多步幂法修正的广义二级分裂迭代法

本文基于计算PageRank的广义二级分裂迭代算法,提出了多步幂法修正的广义二级分裂迭代方法.首先,我们详细介绍了该算法的计算过程.然后,证明了该算法的收敛性,并讨论了迭代参数的选取.最后,通过数值实验说明该算法具有比广义二级分裂迭代方法更少的计算开销和更快的收敛速度.     

渐进迭代逼近方法的数值分析

基于一类特殊矩阵的幂级数展开,推导了渐进迭代逼近方法和代数插值方法的等价性.在此基础上,针对PIA方法中因病态矩阵而导致收敛速度过慢的问题,通过矩阵QR分解引入变换矩阵,再优化迭代矩阵的谱半径,来加速PIA方法收敛;相对于因不同的参数化而导致计算效率的不确定性问题,采用向心加速参数化、优化配置矩阵来确保计算效率.最后通过数值实例验证了理论推导的正确性和文中方法的有效性.     

块三对角线性方程组的一种并行迭代算法

系统工程计算在科学计算中,单台处理机不能满足需要,为提高计算效率和精度,采用并行处理是一个非常好的块三对角线性方程组的办法,提出了分布式环境下求解块三对角线性方程组的一种并行计算,算法是充分利用系数矩阵结构的特殊性,通过对系数矩阵进行适当地分解构造的迭代算法,使得算法需要在相邻处理机之间进行并行通信三次.并从理论上给出了算法收敛的一个充分条件.最后,在HP rx2600集群上进行了数值仿真,结果表明,实算与理论是一致的,提高了并行效率和精度.     

考虑负荷类型的配电网改进牛顿潮流算法

针对传统牛顿法存在计算量大、效率低,且当负荷类型不再是恒功率时其迭代次数与时间会明显增加等问题,提出了一种改进的牛顿潮流法。该算法考虑了负荷类型,将恒功率、恒电流和恒阻抗结合起来组成ZIP负荷模型,采用矩阵分裂以及矩阵求逆运算的松弛方法,使求解过程简单、快捷,有效地提高了算法效率,削弱了负荷类型变化对迭代次数以及迭代时间的影响。采用33节点系统测试比较了算法的迭代次数和迭代时间,证实了算法的有效性;并通过潮流计算结果分析了负荷类型对系统电压的影响,结果表明,恒阻抗负荷比例的增加有利于提高系统节点电压。     

一类Toeplitz三对角方程组的一种分布式并行算法

文中提出一类Toeplitz三对角方程组的一种分布式并行算法。该算法以系数矩阵的分解为基础,充分利用了系数矩阵结构的特殊性,算法因并行化而引入的冗余计算量非常少,算法的通信机制简单,通信量仅与处理 机台数p有关,与方程组规模n无关,算法具有很高的并行效率,理论分析和数值试验表明,其加速比Sp(n)→p(n→ ∞）,此为线性加速比的理想情况。文中给出了算法在分布存储多计算机系统上的数值试验结果。     

求解鞍点问题的一般加速超松弛方法

针对大型稀疏鞍点问题给出了一种含有待定参数的新迭代解法,将其称之为一般加速松弛方法,简记为GAOR方法．当参数α=时,新迭代方法是变成由Golub等人给出的SOR-Like方法．该迭代法的构成是基于对系数矩阵进行的一种分裂．迭代法需要选择一个预处理矩阵和待定参数,通过适当选取预处理矩阵和待定参数,新迭代法是收敛的,并且以定理的形式给出了新迭代方法的迭代矩阵的特征值和参数之间的基本等式,从而也导出了迭代法收敛的充分和必要条件．理论结果表明新方法更具有广泛性,并且适当的选择参数可以使新方法较SOR-Like方法具有更快的收敛速度．在文中的最后给出了迭代法的数值试验结果．     

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.     

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)

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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