OLSR路由协议的改进及其NS2仿真分析

研究了移动Ad hoc网络中的一种典型先应式表驱动路由协议:RFC3626最优链路状态路由协议(Optimized Link State Routing Protocol,OLSR),指出了该协议对MPR(Multipoim Relays)集合选择算法会导致该集合可能存在过多的冗余节点的不足之处,提出了一种改进的OLSR路由协议,通过对原MPR集合中节点的再次排序判断,除去了冗余节点.仿真结果表明:经过改进的OLSR在TC分组的发送数目、节点接受TC分组总数目、平均端到端延迟都得到了很大的改善,从而减少了TC分组的洪泛,提高了网络性能.     

一种基于卡尔曼滤波移动预测的OLSR协议改进

Ad Hoc网络路由协议是影响Ad Hoc网络性能的关键技术之一,最优链路状态路由协议OLSR（Optimized Link State Routing）是Ad Hoc网络中常用的协议之一,但是传统的OLSR协议在高负载、节点快速移动的情况下会导致连接中断和数据的丢失。针对上述问题,本文结合卡尔曼滤波移动预测模型对OL...     

NDN网络中内容源移动的路由更新优化方法

命名数据网络(Named Data Networking, NDN)中,命名链路状态路由协议(Named-data Link State Routing Protocol, NLSR)并非针对移动场景所设计,特别是对移动设备作为内容源的支持上存在FIB更新严重滞后、请求响应延时过大、内容响应率过低等问题。本文提出了一种针对内容源移动问题的NLSR优化方法(optimized NLSR for Source Mobility, NLSR-SM),采用内容源提前报告移动信息,网络中转节点提前更新FIB的策略,实现对内容源移动性的更好支持。在ndnSIM上实现NLSR-SM的原型系统,在不同实验场景下与NLSR进行了对比。实验结果表明,NLSR-SM可以降低请求响应的往返延时,提高内容响应率。尤其对于移动直播的场景,优化机制能够提高单次请求的内容响应率。     

一种基于MAC层拥塞度的MPR选择算法实现及运用

在移动Ad Hoc网络中,随着网络节点移动速度加快,MAC层拥塞程度加剧,势必严重影响网络数据传输成功率和加大传输延时。本文通过对HELLO消息、TC消息的修改来获取并传输MAC层的拥塞信息同时通过仿真实验设定阀值,对OL-SR(Optimized Link State Routing)路由协议进行MPR重定义以实现数据的及时传输。仿真实验表明改进后的方案在节点移动速度较快时,能够显著提高数据传输成功率,增加网络承受负载能力,提高OLSR的路由传输能力。     

航空集群网络可靠性估计路由选择策略

针对未来航空集群网络中节点间通信可靠性保障问题,提出一种基于移动预测的链路可靠性估计路由选择策略。首先,使用基于地理位置的移动预测方法对邻居节点的位置进行准确预测。其次,根据预测结果对当前节点的通信范围进行分区,对不同邻居节点所在区域的链路可靠性分别估计得到相应的可靠性估计函数值。根据得到的可靠性函数值使用概率选择模型并结合跳数因子进行路由选择。最后,以优化链路状态路由协议（Optimized Link State Routing protocol,OLSR）为基础对路由选择策略细节进行描述,并仿真验证了提出的路由选择策略的有效性。实验结果表明,该策略在适用于航空集群网络的基础上,能有效提高网络中节点间通信的可靠性。     

基于身份签名的安全OLSR协议研究

描述优化链路状态路由算法OLSR(Optimized Link State Routing)协议的特点,分析自组网中OLSR路由协议脆弱性以及它可能遭受的各种攻击,并基于身份的签名机制,提出一种基于身份的签名认证的安全OLSR路由协议的解决方案,并对该新路由算法的性能进行仿真比较分析.     

无人机自组网按需寻路的可靠OLSR协议

无人机自组网应用场景中,针对OLSR(Optimized Link State Routing)协议在数据通信阶段,无人机快速移动可能引起通信链路中断,并且OLSR协议没有链路维护机制,导致发包成功率降低和时延增加.在节点入网阶段,无人机无法及时获取全网拓扑信息,导致通信失败.本文借鉴AODV(Ad Hoc On Demand Distance Vector)路由协议中按需寻路思想,提出一种按需寻路的可靠OLSR协议.该算法提出了两个优化思路:基于TC全网寻路机制和基于HELLO邻居寻路机制,通过增加路由获取途径,维护多跳链路的稳定性.通过仿真实验将该协议与现有协议进行比较,实验结果表明,该协议在不增加控制开销的前提下,提高网络的发包成功率,端到端时延和吞吐量.     

一种安全的移动自组网链路状态路由协议：SOLSR

移动自组网是一种新型的无线移动网络，具有无中心、自组织、拓扑结构变化频繁以及开放式通讯信道等特性，因此移动自组网下的路由协议所面临的安全问题比有线网环境下更为严重。OLSR（Optimized Link State Routing）协议于2003年成为RFE3626草案，该协议首先假设网络中所有节点都是友好的，无恶意行为，同时认为安全问题可以利用IPSec来解决，但是，OLSR协议的通讯通常是“一对多”的广播形式，IPSec是针对端到端通讯的安全方案，故而单单依靠IPSec并不能完全解决OLSR的安全问题。由于OLSR自身还存在着机制上的漏洞，恶意节点针对这些漏洞进行攻击，可以导致路由协议无法正常工作，继而影响到整个网络的运行。本文在对OLSR的安全性分析的基础上，对协议进行了改进，加强了协议中对“邻居关系”的定义，同时引入了虫洞检测和身份认证机制，以及通讯报文的安全附加项，从而提出了安全链路状态路由协议——SOLSR来保证移动自组网中路由协议的正常运行。     

移动Ad Hoc网络中基于链路稳定性预测的组播路由协议

节点的随机移动性导致了移动自组织网络拓扑的动态变化,进而增加了重路由的频率,降低了网络通信性能.选择稳定性较高的路径进行路由,能够有效地降低重路由的频率,延长路由的生存时间.基于接收到的数据分组的信号强度,文中提出一种新颖的链路稳定性预测模型,并将其应用于传统组播路由协议中.仿真结果验证了预测机制的有效性,扩展协议LSPMR(Link Stability Prediction-based Multicast Routing Protocol)能够显著地提高分组投递率,降低分组端到端平均传输延时,且控制开销较小.     

一种可扩展动态混合移动自组网路由协议

现有的主动式路由协议和反应式路由协议在节点数目多、节点密度高的场景下性能不够理想,可扩展性较差,而混合路由协议可扩展性相对较好.提出了一种可扩展动态混合移动自组网路由协议--SDHRP(Scalable Dynamic Hybrid Routing Protocol),该协议基于一个分布式动态最大独立集算法.与ZRP的对比实验结果表明,在保证网络吞吐量的前提下,SDHRP的路由控制开销减小了30%左右,具有较好的可扩展性.     

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.     

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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