基于检查点进程迁移机制的改进

目前的大多数进程迁移机制都是基于检查点保存重起机制来实现的。该文在机群环境下，提出一种改进的不保存进程状态的进程迁移机制。先把进程的必要信息转移到目标机上，然后即开始执行新的进程，并在执行的过程当中，陆续转移进程其他的信息。实验表明改进的机制能较大地缩短进程迁移时间。     

分布式计算系统中进程迁移的方法

在分布式计算系统中，进程迁移是一种在进程生命周期内将它从一台处理机传递到另一台处理机上，并使进程从其“断点”继续运行下去的方法。本详细地讨论了在Ｗｕｌｏｒ－７５／３２系统和国外几个典型的分布式计算系统中实现进程迁移的方法，以及为实现进程迁移，对系统的其它机制－件系统，通信机制和内核中有关部分所作的扩充。     

基于消息传递的移动EJB对象强迁移构件模型的研究

移动计算环境下的Agent对象迁移包括强迁移和弱迁移技术。在特定的多环境中，一个重要的问题是合理地为移动Agent对象实现异地迁移计算提供有效的管理和支持，目前使用的支持系统有基于传统解释语言的、基于CORBA平台的和基于Java语言的。在移动Agent对象强迁移技术的理论基础上，提出了一种基于消息传递的移动EJB对象强迁移构件模型，分析与改进了适合强迁移对象进程消息发送的同步消息传递算法，使得该构件模型的消息传递具有很好的同步机制，从而提供了一种良好的移动Agent对象迁移构件化管理支持方式。     

一种两级分布调度算法

针对传统分布式调度算法研究中将调度策略与机制相分离的不足，本文提出了两级分布调度算法，它能较好地结合两种调度机制（远程执行与进程迁移），提高了系统的性能。     

分布式系统中的检查点算法

检查点能够保存和恢复程序的运行状态．它在进程迁移、容错、卷回调试等领域都有重要的应用．本文对分布式系统中的检查点算法进行了详细的分类评述．检查点算法可分为单进程和分布式程序检查点算法，分布式程序检查点算法又可分为异步检查点算法和一致检查点算法．同时本文系统介绍了改进检查点算法性能的典型方法．这些改进算法主要采用两个策略来减少算法的开销与延迟：一是减少检查点文件中需要存储的信息量，如增量算法等；二是提高检查点操作与目标程序运行的并行性，如主存算法等．最后，文章讨论了目前检查点算法的局限性和进一步的工作．     

基于云预存储技术的Docker在线迁移方法

针对基于Docker容器的分布式云计算下出现负载不均衡问题,有必要将较高负载服务器中的Docker容器进程迁移到其他相对空闲的服务器上.而传统的容器迁移算法忽视了容器本身的特征,从而导致在迁移过程中传输效率低下.基于此,利用第三方管理平台和数据预存储阈值机制,提出一种Docker容器动态迁移预存储算法PF-Docker.首先将Docker容器内部进程运行相关文件和流动数据预存至云端存储器,然后通过预存储阈值机制减少流动数据的无效传输,最后在停机传输阶段将流动数据和冗余数据传输给目的服务器.实验表明,该方法在Docker容器迁移中能有效地降低迁移时间,减少数据传输量,提高容器的容错率.     

网格作业自适应迁移模型

作业迁移是实现网格作业服务质量保证和系统高效能的重要方法。该文在分析传统进程迁移技术的基础上,根据网格系统的特点,提出一种全局作业与局部进程相结合的网格作业自适应迁移模型,给出网格作业自适应迁移策略、迁移对象选定原则、迁移时机确定机制和自适应迁移实现算法。试验结果以及在某校园计算网格中的应用验证了该模型的有效性。     

基于内存迭代拷贝的Xen虚拟机动态迁移机制研究

为减少虚拟机动态迁移时间,Xen采用了Pre-Copy算法来选择合适的时间进行停机拷贝,以保证在低负载或空负载时的虚拟机迁移的优越性能,但在高负载环境下,Pre-Copy算法对内存页的重复迭代严重影响了虚拟机迁移的效率。基于Xen虚拟机内存迭代拷贝算法,提出了一种内存分片迭代拷贝机制,即通过缩短迭代拷贝的终止时间来减少虚拟机动态迁移所花费的时间。实验结果表明,内存分片迭代机制可以有效提升Xen虚拟机动态迁移的性能。     

一类基于物种迁移优化的进化算法

借鉴自然界中的物种迁移机制,提出一类基于物种迁移优化的进化算法．该算法是根据生态系统中物种分布的迁移模型而提出的一种优化算法．参考其他智能算法的思想,通过物种迁移实现信息交换和共享,从而完成进化过程．讨论了物种迁移优化算法的基本原理和实现过程,同时进行一些基准函数的性能测试．实验结果表明所提出的算法是有效的,具有一定的参考和应用价值．     

面向同构型多处理机系统的动态负载平衡算法

为了解决同构型多处理机系统中的负载不平衡问题,提出一种分布式控制、发送者驱动的动态平衡算法,该算法利用CPU队列长度衡量处理机负载状态、利用进程执行时间选取适合被迁移的负载、利用较完备的消息机制传播处理机负载状态和负载平衡要求,适用于计算密集型任务.实验结果验证了该算法的有效性.     

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