基于ZigBee的AODVjr算法研究

ZigBee网络的AODVjr算法在路由发现过程中存在大量路由请求包(RREQ)分组洪泛的问题.为此,结合节点能最和Cluster-Tree 算法,提出一种改进的AODVjr算法.在路由选择时尽量避免能量较低的节点,并对RREQ分组的大致方向和传输距离进行控制.仿真结果表明,该算法能有效降低网络总体能耗,合理分担网络负...     

改进的ZigBee网状网络路由算法研究

针对ZigBee网络中AODVjr路由算法存在节点死亡率高、网络能耗大的问题,结合节点的存储结构、能量和链路质量特点,提出一种改进的ZigBee网状网络路由算法F-AODVjr。在路由发现之前,利用路由节点自动维护的邻居表寻找目的节点,以降低因路由请求(RREQ)分组寻址目的节点导致的能量消耗。在路由发现阶段,通过改进AODVjr路由算法的最短路径寻址思想,设计含有路由跳数、节点剩余能量和链路质量的路由算法,寻找具有最低路由成本的优化路径。仿真结果表明,F-AODVjr路由算法可以有效降低网络整体能量消耗,提高节点生存率及数据分组成功投递率。     

基于定向的ZigBee网络节能路由算法

针对ZigBee网络中,AODVjr算法大量转发分组造成的能量损耗与拥塞问题,以及Cluster-Tree算法造成的父节点能量消耗快等能耗问题,以定向转发分组为策略,设计一种基于定向与最小公共树路径的路由算法。通过对加入网络的节点进行区域划分,协调器将区域顺序通报给各路由节点,以使路由节点在发起路由时,从区域顺序中选取最短路由区域,以此减少AODVjr算法中的冗余的RREQ分组。同时,在区域内采用最小公共子树路径与ADOVjr算法相结合的方式,以达到有效减少分组转发的目的,从而降低整个ZigBee网络的能耗,延长网络的寿命。仿真结果证明,该算法能有效地减少整个ZigBee网络在进行路由发现时的路由请求分组转发的数量,降低网络的能耗,提高整个网络的剩余能量百分比。     

一种改进的ZigBee路由优化算法

ZigBee网络在运行的过程中,各个节点工作任务不均匀,从而会使能耗不均匀,导致整个网络过早产生分割死亡,因此提出一种均衡负载的路由优化算法.该算法首先通过发送定向RREQ来减少网络风暴,然后基于单个节点剩余能量、整个网络平均能量、多条路由路径能量代价和多个邻居节点能量这几个因素,通过选择动态路径来构建网络的动态路由,从而避免单条链路的压力.NS2仿真实验表明,改进的路由算法在节点死亡数、能耗和生存时间上都得到优化.     

基于能量选择的ReInForM路由算法研究与仿真

研究网络路由能量优化问题,针对传统的高可靠性路由算法难以均衡能耗的问题,为了实现高可靠性能量优化,提出了基于能量选择的ReInForM路由算法.新算法通过引入节点能耗量化评估机制,将邻居节点集合中待选节点按能耗进行排序,在保证传输可靠性的前提下,优先选择能量消耗少,剩余能量多的节点,从而优化路由算法.新算法解决了在恶劣通信环境下,高可靠性路由算法的能耗均衡问题.仿真验证了新算法在均衡路由能耗,减少失效节点个数,延长网络生存时间方面取得了较好的效果.新算法较传统算法取得更好的效果.     

ZigBee网络路由算法研究与优化

本文先研究分析了当前ZigBee网络支持的3种路由算法,并针对目前最常用的ZBR路由算法在路由发现过程中会产生大量无用RREQ分组且能量消耗快的缺点,本文提出了一种改进的分层能量控制算法.本文从控制节点能量阈值、限制RREQ分组的传播范围、限制网络深度入手对其进行优化,优化后的算法丢弃了不需要的RREQ分组包、降低了网络的能耗.最后通过NS-2进行仿真,实验结果证明,改进后的算法在保证网络传输稳定性的同时降低了时延和能量消耗,使得网络生存时间最大化.     

能量均衡的ZigBee路由算法优化研究

传统的ZigBee路由算法存在泛洪式路由请求(Routing Request, RREQ)消耗网络大量能量和网络内节点能耗不均等问题,缩短了网络生存周期。本文提出一种优化选取转发节点的能量均衡路由算法。在路由发现阶段限制RREQ广播半径,路由选择阶段通过多目标优化选取最佳下一跳节点,并且通过节点间周期性交换休眠时序,实现同步低功耗路由机制。基于NS-2.35的实验结果表明,与传统的ZigBee路由算法相比,本算法可以提高数据包的平均到达率,减少数据包的平均端到端延迟和保持网络内节点能量平衡,进而延长网络生存时间。     

基于能量优化的ZigBee网络路由算法

针对AODVjr算法在路由发现过程中会产生RREQ洪泛,导致节点能量消耗过快的问题,提出了一种改进的ZigBee网络路由算法.改进算法通过邻居表限定RREQ传输范围和父子节点的传递方向,计算路由代价并根据节点剩余能量动态划分所处的能量区域,根据3种能量区域进行差异化路由发现,动态回避剩余能量较低的节点并发现能量较高的节点.仿真实验结果表明,改进算法能实现节点的能量动态平衡,有效控制网络的总体能量消耗,减少死点个数和减缓死点出现的频率.     

WSN中基于最大最小化的优化路由算法

无线传感器网络(WSN)由能量受限的节点组成,需要设计路由算法优化节点的能耗。文章以最大化网络生存时间为目标,基于最大最小化模型提出了优化路由算法,定义了数据发送矩阵,设计了转发节点选择机制,以避免路由回路;基于节点收发数据的能耗及剩余能量,设计了求解优化路由的数学规划模型,优化了传感器节点的数据发送路径和发送量,均衡了节点的能量消耗。仿真结果表明,该算法能有效地均衡节点的能耗,延长网络生存时间。     

基于能量均衡的ZigBee路由算法优化

为了实现ZigBee网络的能量均衡,延长网络生存时间,针对现有基于能量均衡的ZigBee网路路由算法的不足,根据节点父子和位置关系适当控制RREQ包转发方向,提出了针对RN-节点改进邻居表使RN-节点具备路由功能,并定义了考虑因素全面的路由代价和能够实时更新的节点能量等级,从而实现了AODVjr路由算法和Cluster-Tree路由算法基于能量均衡的真正结合。通过仿真与原算法和现有的基于能量均衡的路由算法进行比较,比较结果表明了优化的ZigBee网络总体能量消耗与死亡节点出现时间和数目。     

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