并行程序模型及其哲学家就餐问题解的有效性验证

本文先介绍类似Potri网的并行程序概念,包括基本模型及有效性证明的方法。然后用并行程序模型解决操作系统的一个典型问题——哲学家就餐问题,本文提出该问题的一个并行程序算法作出正确性验证。     

Petri网共享合成及其在并行系统中的应用

为了使Petri网技术能够应用于MPI并行程序的正确性和性能的验证,提出了Petri网共享合成运算构建MPI并行程序Petri网的算法。对分布式并行处理系统MPI并行程序的结构与消息传递过程进行分析,给出并行程序基本语句与传递函数的Petri网,将Petri网共享合成运算从两个Petri网的共享合成运算推广到并行程序的多个Petri网的共享合成运算,给出了推广定理和证明。提出了共享合成构建MPI并行程序Petri网的算法,并在消息传递并行系统中给出构建MPI并行程序Petri网的应用示例。实验结果表明,共享合成运算是构建MPI并行程序Petri网模型的一种有效方法。     

并行程序构造与测试的一种方法

本文以数据驱动的并行计算模型及其证明框架为理论基础,进一步探讨了并行程序构造及其关键步骤即谓词并行分解的理论与方法,得到一些较为实用的结果,在此基础上,最后讨论了并行程序的测试方法以及如何获得数据驱动的并行程序问题。     

采用CSTools在Transputer网上实现并行计算

本文研究利用CSTools在Transputer网上实现并行计算的方法,着重讨论如何利用已有的串行算法设计并行算法、如何利用CSTools进行进程通讯以及如何把并行程序映像到Transputer网等问题。     

负载平衡无关的并行程序最适处理器网格选择

用户在编写并行程序时,通常是把物理处理器看成逻辑的处理器(进程)网格,以便于算法的实现.随着用户可用处理器的不断增多,可选择的网格形状也随之增加,如何为基于消息传递的并行程序选择合适的、能发挥出并行机潜在性能的处理器网格形状,是一个迫切需要解决的问题.在提出基于通信点概念的最小度数通信点集合法之后,通过对并行程序通信模式的分析,试图解决与负载平衡无关的并行程序的最适处理器网格选择问题.通过对ScaLAPACK软件包中的一个并行测试程序——并行Cholesky(对称正定矩阵分解)通信点集合度的分析,此方法成功地选择了最适处理器网格形状,并与实验结果相一致.     

异构网络环境下不确定并行程序行为分析

传统的可达性测试算法可以解决消息传递并行程序测试中的完全性问题,但存在状态空间爆炸的问题,测试开销大。本文通过考虑网络带宽对并行程序行为的影响,对网络带宽异构环境下的传统可达性测试方法进行了改进。实验表明,改进算法有效的减少了测试路径的数量,极大地提高了测试效率,从而减小了开销。改进算法可以高效地、近似完全地测试并行程序。     

确定性并行技术

由于执行个体之间的同步、竞争和干扰,并行程序的执行存在着不确定性问题,即程序在相同输入下多次执行可能得到不同的结果.不确定性给并行程序在开发、调试、测试、容错和安全等方面都带来了挑战,严重降低了并行程序的可靠性,阻碍了并行程序的发展.确定性并行技术通过控制并行程序执行个体间的同步、竞争和干扰,使程序的执行结果仅依赖于输入.确定性并行技术能够从根本上解决了目前并行程序存在的诸多问题,提升了并行程序的可靠性,给并行程序的发展带来了新的机遇.文中调查、分析和比较了目前主流的确定性并行技术和方法,分析了弱内存一致性对确定性并行系统的影响,并对未来确定性并行技术的发展趋势做出了展望.     

一种分布式计算环境下并行应用的调度算法

在网络上运行并行程序不像在并行机上那样可靠,因此对于关键应用需要在应用级保证消息传输的可靠性.人们对以异步方式进行通信的并行程序的调度问题提出了大量的启发式算法,但是它们所产生的调度结果不能用于以同步方式通信的并行程序.提出的PRGSC算法可以防止由同步通信所引起的死锁问题,而且可以降低同步通信所带来的时延的影响.形式化地证明了死锁检测算法的正确性,并通过仿真实验说明了PRGSC算法有很好的调度质量.     

并行程序的优化与性能评价

文中讨论了并行程序的优化问题,指出并行程序的优化应从数据划分、通信优化和串行优化三个方面着手。针对传统加速比的缺点和不足,我们提出了优化加速比模型来评价优化并行程序的性能;对ＮＡＳ基准测试程序ＭＧ和ＦＴ进行了优化,用优化加速比模型分析了上述两个程序在ＩＢＭ ＳＰ２上的性能。     

X10程序的差别分析方法

程序差别分析是程序调试的常见手段,其主要用于分析程序不同版本之间的差异信息.然而,将现有程序差别分析算法扩展到并行程序语言还面临众多挑战.其主要原因在于并行程序复杂性较高,且存在支持并行活动的特殊机制,如地址(或线程)、活动、同步等,从而为有效进行程序差别分析设置了障碍.文中研究基于PGAS模型的X10并行程序的程序差别分析方法,并设计了一种语句级的、针对X10程序的程序差别分析算法X10Diff.X10Diff包括下列步骤:(1)匹配原程序和修改后程序中的类、接口、方法及地址;(2)为待分析程序片段构建基于地址的程序流图,并建立相应简化图;(3)迭代扩展并比较简化图,并将差别信息定位到代码中.     

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