精英交叉二进制蝙蝠算法求解0-1背包问题*

针对基本蝙蝠算法收敛速度慢,易早熟的问题,提出了一种精英交叉二进制蝙蝠算法。该算法借鉴精英策略和遗传算法中的交叉机制,按照一定比例选择蝙蝠群中的精英个体进行交叉,将得到子蝙蝠群和父蝙蝠群进行混合择优,保证蝙蝠群的多样性和优秀性,提高了全局搜索能力;为提高局部搜索能力,算法在对每个个体计算适应度值时加入贪心策略;另外,通过对蝙蝠群最优解进行动态监测,适时对种群进行柯西变异,使算法具有跳出局部极值的能力。通过对5个实例的仿真计算比较表明,该算法与改进贪心遗传算法,贪心二进制蝙蝠算法和病毒协同蝙蝠算法相比,无论是收敛速度还是寻优能力都表现优异,为求解0-1背包问题提供了一个实用的算法。     

基于SDN的卫星网络多控制器部署方法研究

针对传统卫星网络协议的异构性、网络配置不灵活、不能提供细粒度服务等问题,本文基于SDN的卫星网络架构,提出了一种改进的NSGA-II的多目标控制器初始化部署算法,以实现卫星网络的灵活控制。该方法在SDN卫星网络的架构基础上以低时延和负载均衡为优化目标,通过矩阵的形式对个体进行编码,同时提出行交叉和列交叉以及行变异和列变异操作,通过不断迭代进化,得出最优的控制器部署方案。实验证明,与传统的贪心算法以及随机算法相比,所提出的算法能够降低控制器和交换机之间的网络时延,同时使各控制器的负载保持均衡。     

求解0-1背包问题的二进制蝙蝠算法

为了求解离散空间中的最优化问题,提出了一种二进制蝙蝠算法,并引入时变惯性因子来提高算法的全局收敛速度;在此基础上,为提高求解0-1背包问题时找到最优解的机率,利用贪心优化策略对无效的蝙蝠个体进行优化,从而给出了贪心二进制蝙蝠算法（GBBA）。仿真计算结果表明,GBBA算法在寻优能力和收敛性能方面比已有的GMBA算法都更优越。     

面向多核系统的蚁群最优化能耗调度算法

主要研究多核系统的能耗最优化问题。首先,根据多核系统的特点,建立关于多核系统的任务、能耗模型;接着,设计和实现一种基于蚁群最优化能耗调度算法。本文算法以蚁群算法的概率状态转移规则为核心,通过全局信息激素更新的策略,避免了陷入局部最优的情况,从而获得全局最优解。通过实验比对,分别与贪心算法、穷举算法比较后发现：本校提出的调度算法,在最佳情况下,仅比最优能耗高0.7%,而该算法复杂度低,可以应用于任务输入集较大的场景。      

Multi-Radio无线传感器网络中基于缓存和信道切换的数据查询算法的研究

针对Multi-Radio Multi-Channel传感器网络中链路服务质量和信道冲突等问题,提出并证明了基于缓存和信道切换的数据查询问题是一个NP完全问题.根据数据流守恒和链路-信道等约束条件,建立线性规划方程,得到该问题的最优解模型,并提出了一个多项式时间的近似算法——贪心新覆盖数据算法.该算法采用动态规划策略最小化缓存节点将单位数据包传输到查询节点所需要的路径时延,再贪心选择其具有最小路径时延的缓存节点,收集其新覆盖数据.理论分析和实验结果表明,提出的方案能有效地减少数据收集时延,提高数据查询效率.     

面向低能耗的虚拟机部署和迁移策略

为提高数据中心的资源利用率并降低能耗,提出了面向低能耗的虚拟机部署和迁移策略,包括虚拟机初始部署算法BT-MPA和虚拟机动态迁移算法MMT-MMA。BT-MPA算法基于回溯法实现虚拟机集合和主机集合的最优初始映射,MMT-MMA算法基于最小迁移时间策略实现虚拟机动态迁移。仿真验证了所提出策略能够在降低数据中心总能耗的同时避免了不必要的迁移开销。     

面向数据中心的虚拟机部署及优化算法

虚拟机动态配置是解决数据中心能耗低效的有效方法。针对动态配置过程中的虚拟机部署及优化问题展开研究,提出一种新的面向系统能耗的虚拟机部署算法以及基于主动迁移的优化策略。为了降低系统能耗,新算法采用基于服务器利用率的最佳适配降序算法求解虚拟机部署方案;同时为了适应应用负载的动态变化,新算法启动主动迁移策略对部署方案进行优化,即通过启发式算法在当前部署的基础上搜索使系统能耗更低的优化方案,并根据新部署对虚拟机执行主动迁移。考虑到迁移会导致应用服务质量降级和额外能耗,新算法通过在优化策略中设置基于服务器利用率的启动门限,对虚拟机主动迁移频率进行控制。仿真实验表明,所提算法在系统能耗、虚拟机迁移频率、服务器状态切换频率以及服务质量等多项性能指标上均有显著提高     

求解0-1背包问题的混沌二进制乌鸦算法

针对离散空间的最优化问题,提出了二进制乌鸦算法,并在初始解中利用Chebyshev映射产生两种混沌序列优化乌鸦的初始解,保证个体的初始位置在整个搜索空间均匀分布;然后,为快速有效地求解0-1背包问题,引入贪心修复与优化策略处理非正常编码个体,得到基于混沌理论的二进制乌鸦算法（chaotic binary crow search algorithm,CBCSA）。仿真实验表明,CBCSA具有良好的全局寻优能力和收敛速度,能快速求得最优解,且混沌序列的第一映射方式比第二映射方式性能更佳。     

基于粒子群优化算法的虚拟机部署策略

针对云计算基础设施即服务(IaaS)中的虚拟机部署问题,提出一种基于粒子群优化(PSO)算法的部署策略。由于PSO算法在处理虚拟机部署这类大规模复杂问题时,具有收敛速度慢且容易陷入局部最优的缺点,首先,引入多种群进化模式提高算法收敛速度,并在此基础上加入高斯学习策略避免局部最优,提出了一种多种群高斯学习粒子群优化(MGL-PSO)算法;然后,根据部署模型,使用轮询(RR)算法对MGL-PSO进行初始化,进而提出了一种以负载均衡为目标的虚拟机部署策略。通过在CloudSim中进行仿真实验,验证了在解决虚拟机部署问题时,MGL-PSO相比PSO算法,具有更快的收敛速度,并且负载不均衡度降低了13.1%。在两种实验场景下,所提算法相比随机负载均衡(OLB)算法,其负载不均衡度分别平均降低了25%和15%;相比贪婪算法(GA),使负载不均衡度分别平均降低了19%和7%。     

基于冗余任务消减的边缘应用性能优化

在增强现实应用中，距离较近的多个用户请求很可能是相似或者相同的，从而导致同样的计算任务被重复执行。针对该问题，设计基于冗余任务消减的计算任务缓存系统。通过在边缘节点设计任务缓存，使边缘服务器以自组织方式维护全局缓存。对客户端请求时延、用户轨迹、节点部署和总时延进行建模，基于此研究基站上边缘服务器的计算资源部署问题，在给定总的部署代价下优化平均请求时延，并将该问题转化为整数非线性规划问题，设计针对中小规模场景的IDM算法和针对大规模场景的LDM算法。实验结果表明：IDM算法的平均时延与参考最优解仅相差5.85%，对最优解具有较好的逼近效果；LDM算法在牺牲9.20%平均时延的情况下，相比于IDM算法运行时间缩短98.15%，大幅减少了运行开销。     

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.     

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.     

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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