移动Ad Hoc接入网中外地代理选择算法的研究

在Ad Hoc接入网中，Ad Hoc节点通过外地代理与骨干网中的对等节点通信。外地代理的选择算法是影响Ad Hoc接入网整体性能的主要因素之一。针对Jelger算法存在切换频繁和平均跳数较大的缺点，该文提出了一种基于跳数和路由稳定度的改进算法。相对于Jelger算法，改进的算法可以减少切换次数和移动节点到外地代理的平均跳数，同时具有更小且更加稳定的丢包率。     

改进的PMIPv6域内路由优化策略

代理移动IPv6移动节点发生域内切换时,存在着重建路由优化路径时延长、切换开销大的问题,为此,提出一种改进的代理移动IPv6域内路由优化方案.在移动节点即将发生域内切换时,由新接入的移动网关发起切换,减少了切换过程中本地移动锚点的参与,在移动节点接入新网络之前完成优化路径的建立.仿真实验结果表明,新方案在切换时延和切换开销方面的性能优于原有的代理移动IPv6域内路由优化方案.     

一种基于外地代理的移动IP组播机制的研究

在继承ABMoM方案优点的基础上,本文提出一个组合远程预订、双向隧道技术的基于外地代理的移动IP组播方案。与ABMoM相比,由外地代理来支持组播,兼任本地组播路由器的职责。移动主机直接向外地代理登记,外地代理通过改进的组管理协议来管理本地组成员,并使用任何路由机制和其它组播路由器进行交流。很好地解决了组播代理和外地代理之间的通信开销问题,同时通过改进组管理协议和引入外地代理的缓冲技术,能减小切换所造成的影响,保证子网的平滑切换。     

RSVP在无线移动网络中的扩展研究

讨论了RSVP协议应用在无线移动网络中存在的问题,分析比较了目前对RSVP的两种改进方法,提出了一种在无线移动网络中对RSVP的扩展方案。该方案在每个蜂窝添加移动代理,采用组播支持节点的移动性,利用GPS进行移动预测,并且主动进行数据流路径切换。本方案可以在不影响网络容量的前提下,提高移动节点的切换成功率和通信连续性,保证移动节点的服务质量。     

一种基于预测的移动IPv6动态调整快速切换算法

移动IPv6协议是下一代网络中移动节点实现无缝漫游的一种基本技术.但移动IPv6切换时延迟较大,不能满足实时业务的需求.本文提出一种基于预测的移动IPv6动态调整快速切换算法,根据移动节点的运动轨迹和移动速度预测出提前三层切换的正确时机,实现在二层切换之前完成三层切换,减少切换延迟.利用以前的三层切换时间,动态调整时间比较参数Treg,减少预测误差.仿真结果证明本算法在切换延迟和丢包率方面性能优越.     

基于群集移动节点的切换算法

无线蜂窝网的信号切换依赖IP层的移动切换,IETF提出的代理移动IPv6(PMIPv6)协议可以保证移动终端应用IPv6网的快速切换,但是它在切换时延方面仍然无法保证实时通信的服务质量。研究基于PMIPv6协议,提出群集移动节点(CMN)算法,应用媒体无关切换(MIH)技术,减少了大量移动节点,同时提出切换请求时系统时延增大的问题,扩展原始代理绑定更新消息结构(A-PBU)。最后模拟网络模型和节点移动模型,从切换时延方面分析算法的有效性。实验结果表明,系统应用CMN算法与原始切换算法相比可以大大降低切换时延。     

移动IPv6切换技术

在移动IPv6网中,移动节点在不同子网问移动时产生切换,由此产生的延时和丢包问题限制了移动IPv6的应用.可见,移动IPv6切换技术的研究刻不容缓.概述了移动Ipv6切换技术的发展情况及其工作原理,详细阐述了几种基本的改进切换技术,并在此基础上对三种针对时延改进的切换技术进行时延分析.通过分析,可以看出这三种改进的切换技术确实能有效减少切换时延,从而提高切换性能.其中,层次型快速切换是最能减少切换时延的一种方法.     

6LoWPAN无线传感器网络移动管理方案

提出了一种跨层的6LoWPAN无线传感器网络移动管理方案。首先提出了6LoWPAN网络体系结构, 基于该体系结构, 提出了一种跨层的移动切换算法。在此算法中, 网络层移动切换与链路层移动切换同时进行, 在三层切换过程中, 移动节点无须转交地址配置, 也无须参与网络层的移动切换过程, 且无须参与移动切换过程, 在二层切换过程中, 移动节点无须扫描所有信道, 通过获取的信道信息直接进行二层切换, 因此降低了切换延迟、丢包率和切换代价。     

一种基于三方密钥协商的移动IP注册协议

目前大多数移动IP注册协议都是采用对称密码体制和基于公钥密码体制相结合的方式来实现移动实体之间的相互认证,移动节点和外地代理之间没有认证,存在一定的安全缺陷。针对这种移动IP注册协议的认证安全问题,将无证书的三方密钥协商方案引入到移动IP的注册,提出了基于三方密钥协商的移动IP注册协议,实现移动节点、家乡代理和外地代理这三个实体的相互认证。分析结果表明,协议具有更高的安全性,且拥有较高的效率。     

一种新的基于移动IP外地代理分层结构的注册方案

为了在移动网络中运用IP协议,因特网工程任务组(IETF)制定了MobileIP协议。移动IP技术给人们带来极大便利的同时,也造成了许多安全隐患。本文提出一种基于移动IP外地代理分层结构的注册方案,该方案对现有外地代理分层结构的注册方案加以改进,使得移动IP快速切换能力得以提高,减少了注册时延,并提高了移动节点注册过程的安全性。     

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