基于链路状态认知的无线Mesh网路由协议

在分析无线Mesh网路由协议所面临挑战的基础上,结合无线Mesh网络的性能要求,以优化链路状态路由(OLSR)协议为原型,采用跨层设计理论,提出了一种基于链路状态良好程度的路由协议LR-OLSR。该协议引入了认知无线网络中的环境感知推理思想,通过对节点负载、链路投递率和链路可用性等信息进行感知,并以此为依据对链路质量进行推理,获得网络中源节点和目的节点对之间各路径状态良好程度的评价,将其作为路由选择的依据,实现对路由的优化选择,提高网络的吞吐量,达到负载均衡。通过与OLSR及其典型改进协议P-OLSR、SC-OLSR的对比仿真结果表明,LR-OLSR能够提高网络中分组的递交率,降低平均端到端时延,在一定程度上达到负载均衡。     

一种基于两级缓存的协同缓存机制

信息中心网络（information-centric networking,简称ICN）将网络通信模式从当前的以地址为中心转变为以信息为中心.泛在化缓存是ICN重要特性之一,它通过赋予网络任意节点缓存的能力来缓和服务器的压力,降低用户访问延迟.然而,由于缺少内容热度的分布感知,现有ICN缓存策略仍存在缓存利用率较低、缓存位置缺乏合理规划等问题.为了解决这些问题,提出一种基于两级缓存的协同缓存机制（a cache coordination scheme based on two-level cache,简称CSTC）.将每个节点的缓存空间分为热度感知和协作分配两部分,为不同热度的内容提供不同的缓存策略.同时,结合提出的热度筛选机制和路由策略,降低了缓存冗余,实现了缓存位置优化.最后,基于真实网络拓扑的仿真实验表明,CSTC在次热门内容缓存数量上提升了2倍,缓存命中率提升了将近50%,且平均往返跳数在多数情况下优于现有On-path缓存方式.     

基于朋友圈和节点感知的内容中心MSN路由机制

为了解决移动社交网络(MSN)中由于网络拓扑的时变性以及节点资源的受限性导致路由时延长、投递率低等诸多难题,利用信息中心网络(ICN)内容和位置分离的特点更好地支持终端移动性和网内缓存,设计了一种基于朋友圈和节点感知的内容中心MSN路由机制(FACMR)。首先,明确了节点模型的功能表,使节点具有感知能力。然后,基于节点关系强度和其缓存内容相似性构造朋友圈,快速高效地指导路由。其次,利用缓存特征和置换策略进行朋友圈的维护。最后,利用网络模拟器(NS3)对FACMR进行仿真。仿真结果表明,FACMR与现有的典型算法相比,缓存置换率减少了6.35%,误包数减少了22.9%,平均路由时延降低了43.5%,是一种可行且高效的MSN路由机制。     

基于Q学习的蚁群优化水声网络协议

针对水声通信中数据传输延时高且动态适应性弱的问题, 提出了一种基于Q学习优化的蚁群智能水声网络路由协议(Q-learning ant colony optimization, QACO). 协议包括路由行为和智能决策部分, 在路发现和维护阶段, 依靠网络智能蚂蚁进行网络拓扑环境的构建和节点之间的信息交换以及网络的维护. 在Q学习阶段, 通过定量化节点能量和深度以及网络传输延时学习特征作为折扣因子和学习率, 以延长网络的生命周期, 降低系统能耗和延时. 最后通过水声网络环境进行仿真, 实验结果表明QACO在能耗、延迟和网络生命周期方面都优于基于Q学习辅助的蚁群算法(Q-learning aided ant colony routing protocol, QLACO)和基于 Q-learning 的节能和生命周期感知路由协议(Q-learning-based energy-efficient and lifetime-aware routing protocol, QELAR)和基于深度路由协议 (depth-based routing, DBR)算法.     

基于链路状态感知的无线Mesh网优化路由协议

在分析无线Mesh网路由协议所面临的挑战的基础上,结合无线Mesh网络的性能要求,以OLSR协议为原 型,采用跨层设计理论,提出了一种基于链路状态良好程度的路由协议工R-)工SR。该协议引入了认知无线网络中的 环境感知推理思想,通过对节点负载、链路投递率和链路可用性等信息进行感知,并以此为依据对链路质量进行推理, 将其作为路由选择的依据,实现对路由的优化选择,提高网络的吞吐量,达到负载均衡。仿真结果表明,工R-OI_SR能 够在很大程度上提高网络中分组的递交率,降低平均端到端时延,在一定程度上达到负载均衡。     

基于冲突避免的DSR协议研究

基于自适应移动多跳Ad Hoc网络,针对其DSR协议的路由缓存机制,分析不足之处,探索对现有的路由缓存机制的优化方法.提出了缓存路由有效期的概念,为网络中节点的路由表添加一个用于反馈的“缓存路由跳数”参数,节点选择此参数值最小者的路由信息.仿真实验表明,经过改进的缓存机制有效地避免了响应冲突问题,实现了路由的最短优化,在平均传输延迟、分组投递率、吞吐量性能方面都有提高.     

移动无线传感器网络中的两跳信标交换协议

在地理位置路由协议中,周期性信标交换协议(Hello协议)被广泛地用于构建和维护邻居节点表。然而在高度动态的网络环境中,邻居表中会存在很多过期节点,这将导致大量的重传,严重影响路由协议性能。为提高邻居表的准确性,提出一种两跳信标交换协议(T-Hello协议),通过掌握两跳范围内的节点位置信息,节点可以显式地感知邻居节点是否已移出通信范围,以便及时将过期节点从邻居表中删除,而不必等到超时。通过分析各种网络条件(节点密度、交换周期、节点移动速度、通信半径等)对新协议性能的影响,表明对于GPSR协议, T-Hello协议能够缩短过期节点50%左右的存在时间,从而有效地改善了路由效果。     

一种面向认知网络的QoS路由协议

随着网络应用的快速发展,传统网络面临诸多挑战,难以满足新型应用的服务质量QoS(Quality of Service)需求,网络管理变得极其复杂,迫切要求网络具备认知能力.文中提出了一种面向认知网络的QoS路由协议.为了满足不同应用的QoS需求,路由请求对应不同业务类型和服务等级,映射到相应的QoS参数.文中赋予路由节点感觉、活动感、记忆、查找、决策、执行、推理、解释等认知行为,设计了与这些行为相对应的协议报文,支持节点之间通过这些报文进行交互,从而具备认知能力.节点只收集和维护局部邻居和链路状态信息,通过使用和维护经验路段信息提高路由效率.文中对所提出的路由协议在原型系统上进行了实现,对协议的多项性能指标进行了评价.实验结果表明,文中所提出的路由协议是可行和有效的.     

认知无线电网络中的频谱感知安全机会路由协议

针对认知无线电网络中频谱的动态特性及潜在的节点选择性转发问题,提出频谱感知安全机会路由S2OR协议。在频谱感知阶段,通过对主用户活动建模来分析认知节点之间链路的可用概率。在路由选择阶段,采用信任管理方式来考查节点转发行为的可靠性,以便选择可信任的中继节点并保证数据传输的完整性。协议通过获取局部网络状态信息,计算由链路可用概率、链路质量和节点信任度构成的综合型指标——期望吞吐率,允许认知节点在此基础上机会式地选择候选转发节点与数据信道。仿真结果表明,S2OR能够很好地适应频谱动态特性,获取较高的吞吐量,同时减小节点恶意攻击带来的影响。     

分组无线网缠绕多路径数据路由协议仿真

在分组无线网的路由协议中,传统路由协议在恶意节点数目较多时网络吞吐量较低,因此提出一种分组无线网缠绕多路径数据路由协议,利用获取的源节点数量信息与位置信息进行路由发现;根据路由发现结果建立从汇聚节点至源节点之间的路径,从而建立缠绕多径路由;对缠绕多径路由进行建簇与重构;进行支路径数优化,从而实现分组无线网缠绕多路径数据路由协议的构建。为了验证上述路由协议的网络吞吐量,将路由协议与基于链路状态的主动式多路径路由协议、基于动态源的按需式多路径路由协议、基于距离矢量的混合式多路径路由协议进行对比,上述四种路由协议在恶意节点数目为30时的网络吞吐量分别为69.5%、33.5%、23.6%、4.2%,通过比较可知,新提出的路由协议的网络吞吐量最高,证明了新路由协议的性能。     

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.     

Only connect: teaching, technology and telesis

Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained.     

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.     

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.     

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