基于改进引力搜索算法的交换机迁移策略

针对多控制器软件定义网络（SDN）中交换机迁移策略迁移代价衡量单一,不能适应交换机流量的变化的情况,提出基于改进引力搜索算法的交换机迁移策略（IGS-SMS）。在决策阶段,应用基于模糊满意度的多目标决策方法,优化目标根据隶属度大小竞争优先权;在计算阶段,通过改进引力搜索算法优化优先权高的目标函数。实验结果表明,IGS-SMS在实现负载均衡的同时,能保证传输时延与交换机重分配的指标;在实验中,当局部负载较重时,动态迁移算法（DSMA）和基于改进型拍卖交换机迁移机制（PASMM）不能缓解控制器过载,而IGS-SMS执行后无控制器过载,且负载均衡度小于DSMA和PASMM。     

SDN多控制器网络中基于交换机迁移的动态负载均衡策略

针对多控制器SDN网络环境下的负载均衡问题,论文提出了一种基于交换机迁移的动态负载均衡策略,共分为三个实施阶段:首先通过动态信息采集算法(DIA)收集各控制器间的负载信息,以决定需要实施交换机迁移算法的过载控制器;随后依据论文定义的迁移域及迁移交换机选取算法(MSS)决定迁移目标控制器以及需要迁移的交换机;最后依据交换机迁移协议完成交换机迁移,实现多控制器下的负载均衡.仿真实验结果表明负载均衡后SDN网络中交换机的吞吐率显著提升,且各控制器负载逐渐趋于均衡.     

基于模糊满意度的软件定义网络交换机迁移策略

针对软件定义网络中多控制器间负载均衡的迁移代价和迁移效率问题,提出一种基于模糊满意度的交换机迁移策略。首先,构建均衡判断矩阵,监测控制器负载状态,且提出交换机组选择度,划分交换机组以选取迁移交换机;其次,考虑迁移代价和负载均衡率,构建模糊满意度迁移竞争模型,且提出改进蚁群算法优化求解,选择最佳迁入控制器;最后,将迁移交换机迁往迁入控制器,实现交换机的快速迁移。实验结果表明,与现有交换机迁移策略相比,所提方法在保证较高负载均衡率的同时,进一步优化了网络性能,迁移代价平均减少约26.8%,控制器平均响应时间缩短约0.41 s,改善了交换机迁移过程。     

面向SDN负载均衡的交换机自适应迁移策略

针对软件定义网络(SDN)多域部署中存在的子域控制器负载不均衡问题,提出了一种面向SDN负载均衡的交换机自适应迁移策略。首先,通过检测各子域控制器的负载,在网络中基于自适应遗传算法选择迁入和迁出域,可以实现全局最优迁移域的选取;然后,应用生存期和淘汰机制将迁出域中的高负载度交换机迁移至迁入域,有效地均衡了控制器负载。仿真结果表明,与现有的交换机迁移算法相比,迁移效率提升了19.7%,各个子域控制器的负载和交换机的数量到达了均衡,增强了网络的稳定性。     

SDN中基于生物启示的控制器负载均衡机制

针对SDN多域部署中存在子域控制器负载不均衡现象,基于生物领域物种遗传和种群迁徙的启示,依据交换机迁移,提出了SDN控制器负载均衡机制.首先综合网络中主要开销,应用生物遗传的思想,设计了最优迁移域选择算法,得到最优迁入/迁出域;同时类比种群迁徙现象,对交换机应用存活期和淘汰机制,设计了交换机竞争迁移算法,均衡了子域交换机数量.仿真结果表明,与现有算法相比,迁移域的选取过程得到优化,均衡子域控制开销,有效保证了控制器负载的均衡分布.     

SDN中基于迁移优化的控制器负载均衡策略*

针对SDN多控制器负载均衡过程中交换机迁移僵化和迁移冲突问题,本文对现有的交换机迁移模型实施优化,提出了一种阶段式控制器负载均衡策略。在阶段1,综合控制器的各类开销代价,基于遗传算法优化迁移目标,选取交换机迁入和迁出域;在阶段2,通过设定子域迁移度和交换机有效期,实现了多交换机的协调迁移。仿真结果表明,与现有的负载均衡策略相比,改善了迁移域的选取过程,优化了交换机到控制器的动态部署,控制器负载均衡率提升了约21%。     

一种动态自调节的SDN控制器负载均衡算法

为了解决交换机与控制器之间的静态配置会造成控制器间负载的不均衡问题,综合考虑控制器的实时负载和其自身的处理能力,提出一种基于交换机迁移机制的动态自调节的负载均衡算法。该算法可根据系统整体的负载自动选择分配负载的控制器,保证性能高的控制器分配到较多的负载,从而解决多控制器间负载不均衡问题。实验表明,该算法能有效提高系统平均吞吐量及降低平均响应时延,达到更好的负载均衡效果。     

基于自优化的SDN交换机动态迁移机制

为提高SDN控制器的使用效率以及多控制器之间的负载均衡度,对多控制器的部署问题进行了研究,并提出了一种交换机动态迁移机制.该动态迁移机制基于周期性运行的自优化的算法实现,按照控制器的部署情况,将网络划分成多个域,通过分析各域内相关参数,分别找出负载最高和最低的控制器节点,并根据控制器负载和交换机请求率快速选择出最佳的迁移交换机和迁移目的地.控制器的负载均衡度、交换机请求的处理时延和算法的复杂度是算法设计中所考虑的主要因素.该算法的优点在于通过局部的动态调整实现了对SDN控制层的灵活管理.仿真结果表明,基于自优化的交换机动态迁移方案能够有效提高多控制器间的负载均衡度,减小流请求的处理时延,同时将运算复杂度保持在一个相对合理的水平.     

基于SDN的动态负载均衡策略

针对SDN中静态网络结构不能适应动态流量变化所引起的控制器负载不均衡问题,提出一种阶段式动态负载均衡策略。阶段一以控制器负载均值化为目标,确定迁入控制器候选集,且综合考虑时延、负载,设计指标函数,选取待迁移交换机;阶段二考虑网络节点间的连通性,以最小迁移代价为目标,提出改进的EMD模型,并用线性逼近算法快速求解,实现了交换机的快速并行迁移。实验结果表明,与现有的负载均衡策略相比,其改善了迁入控制器和交换机的选取过程,优化了网络性能,控制器的负载均衡度提升了约31.4%。     

基于多目标优化的软件定义网络负载均衡方案

针对软件定义网络（SDN）中控制平面的负载均衡问题,提出了一种基于多目标优化的动态交换机迁移算法（M-DSMA）。该算法首先将交换机与控制器之间的映射关系转变为0-1矩阵优化问题;其次,通过基于NSGA-Ⅱ的多目标遗传算法同时优化控制平面负载均衡度和交换机迁移所产生的通信开销这两个相互冲突的目标。在多目标优化过程中,利用适应度函数选择个体进行交叉变异,随后采用快速非支配排序对种群进行精英策略,产生下一代种群,使得整个种群不断进化,搜索较优的解。仿真实验结果表示,相比于动态交换机迁移算法（DSMA）,M-DSMA在有效均衡控制平面负载的同时,降低了30%~50%的通信开销,且在提高控制平面可扩展性方面具有明显优势。     

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.     

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.     

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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