基于最优簇首数划分单元格的改进GAF算法

为构造良好的拓扑结构, 降低节点能耗, 延长网络生存期, 对传统的GAF算法进行了改进。改进算法中考虑到连通度和最优簇首数的问题, 提出了新的虚拟单元格划分方法。在簇首选择阶段, 不仅考虑到节点剩余能量及节点距基站的距离, 还考虑到节点吞吐率的问题, 并通过定义簇首选择函数来进行簇首选择。仿真结果显示, 改进的GAF算法有效地节省了节点能耗, 延长了网络生存期。该算法的各项性能均优于传统的GAF算法。     

一种基于蜂窝结构的改进GAF算法

能量问题是无线传感器网络协议设计过程中的核心问题,针对该特点在传统GAF算法基础上提出了基于蜂窝结构的改进GAF算法.该算法提出以蜂窝结构虚拟划分单元格,增加单元格边长,扩大单元格面积,将单元格重叠区域中的节点作为骨干网中转节点来实现簇间的多跳通信.通过理论计算和仿真实验对算法进行了性能分析和验证,仿真结果表明该算法能有效地降低节点平均能量消耗,延长传感器网络生命期.     

虚拟力导向的无线传感器网络覆盖策略

摘要;通过建立传感器节点与节点、节点与目标之间的虚拟力模型,制定一种新的簇头选择策略,将节点剩余能量和距离目标的大小作为参数,选择离目标近且剩余能量大的节点作为簇头,提高网络覆盖率;通过虚拟单元格进行分簇,以保持簇头节点之间的数据通信,同时休眠其它非簇头节点的周期性轮换簇头的方式来优化节点能耗,以此来延长网络寿命.与经典GAF算法比较,理论分析和仿真实验结果表明了该算法在网络覆盖率和节点生存时间上均有明显的优势.     

基于蜂窝虚拟网格的WSN混合多跳分簇路由算法

为了延长网络生存周期,均衡网络能耗,提出一种蜂窝网格的混合多跳路由算法。该路由机制采用正六边形进行单元格划分,在簇头选择阶段引入节点角度比、距离比和吞吐率优化阈值函数自主选择簇头。数据传输时采用簇内单跳和簇间混合跳的模式,在各簇头节点之间传输数据时对路径进行优化减少能量消耗。仿真实验表明,该协议在保证网络高覆盖率下,与传统LEACH、GAF、CRVB算法比较在平衡能耗,延长网络整体寿命上占有优势。     

GAF传感器网络中MAC地址空间复用算法

MAC地址只需要局部唯一而无需全局唯一,可对同一MAC地址在不同区域进行空间复用。在GAF算法形成的特殊的虚拟单元格拓扑结构中,可以对簇头节点和簇内节点采取不同的MAC地址复用策略。分析簇头节点和簇内节点MAC地址空间复用的限制条件及复用方法,在此基础上提出一种分布式的MAC地址空间复用算法。理论分析和模拟实验表明,该算法能有效减少MAC地址长度、节约网络能耗,在密集网络中能保持良好的性能。     

无线传感器网络层次型拓扑结构控制

无线传感器网络拓扑控制是在满足网络覆盖和连通度的前提下,通过骨干网节点选择,剔除节点之间不必要的无线通信链路,生成一个高效的数据转发网络拓扑结构。层次型的拓扑结构控制利用分簇机制,让一些节点作为簇头节点,由簇头节点形成一个处理并转发数据的骨干网,其他非骨干网节点可以暂时关闭通信模块,进入休眠状态以节省能量。研究了改进的GAF虚拟地理网格分簇算法和TopD isc成簇算法。     

基于非竞争机制的改进GAF拓扑控制算法

能量问题是制约无线传感器网络发展和应用的瓶颈之一。为均衡网络节点的能量消耗,延长网络的生命周期,需要建立高效的拓扑控制机制。在深入研究GAF算法的基础上,提出了一种基于非竞争机制的改进算法。利用建立的适合度函数和顺序表优化了簇头的选举策略;通过改进虚拟单元格的划分方法,并推导出动态剩余能量阈值估算公式,有效地改善了GAF算法的相关性能。仿真结果表明,改进算法对于减少拓扑控制耗费、延长网络生命周期具有显著效果。     

基于非竞争机制的改进 GAF 拓扑控制算法

能量问题是制约无线传感器网络发展和应用的瓶颈之一.为均衡网络节点的能量消耗,延长网络的生命周期,需要建立高效的拓扑控制机制.在深入研究 GAF 算法的基础上,提出了一种基于非竞争机制的改进算法.利用建立的适合度函数和顺序表优化了簇头的选举策略;通过改进虚拟单元格的划分方法,并推导出动态剩余能量阈值估算公式,有效地改善了 GAF 算法的相关性能.仿真结果表明,改进算法对于减少拓扑控制耗费、延长网络生命周期具有显著效果     

一种基于GAF的无线传感器网络分簇算法

分簇技术主要目标是延长整个传感器网络的生存时间。好的分簇技术可以提高无线传感器网络的可扩展性。就"热区"内的负载平衡问题,以及频繁的簇头轮换和簇重组问题,对基于GAF算法的完全簇头选择算法进行改进,结合双簇头模型和单簇头模型的优点,提出了一种无线传感器网络簇头非均匀分布算法,有效地平衡"热区"内节点的能耗,延长了无线传感器网络的生命期。     

一种基于GAF的无线传感器网络分簇算法

分簇技术主要目标是延长整个传感器网络的生存时间.好的分簇技术可以提高无线传感器网络的可扩展性.就"热区"内的负载平衡同题,以及频繁的簇头轮换和簇重组问题,对基于GAF算法的完全簇头选择算法进行改进,结合双簇头模型和单簇头模型的优点,提出了一种无线传感器网络簇头非均匀分布算法,有效地平衡"热区"内节点的能耗,延长了无线传感器网络的生命期.     

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