一种LEACH协议的多级分簇改进算法

LEACH协议的簇头节点分布不均,导致网络负载不均衡.为此,提出一种LEACH协议的多级分簇改进算法.将网络划分为若干小单元,采用多级分簇相结合的方法,在簇头节点选举过程中引入节点剩余能量作为参考度量,以减少簇头节点与sink 节点之间的通信能耗.仿真结果表明,当网络规模增加到200节点时,该算法在第420轮出现第一个死亡点,优于LEACH协议,能延长网络生存周期,降低网络能量消耗.     

一种基于LEACH协议改进的簇间多跳路由协议

为了均衡无线传感器网络的能量消耗,延长网络的生存时间,在研究几种基于均匀分簇和非均匀分簇的路由协议基础上,提出一种基于LEACH协议改进的簇间多跳路由协议。该协议引入能量因子和距离因子修正了LEACH协议的阈值函数。在簇间通信过程,簇头节点与Sink节点之间采用多跳通信方式,簇头与簇头之间形成一条通向Sink节点的优化路径。实验结果表明,相比于LEACH协议和EEUC协议,本文提出的新协议能够有效的均衡网络的能量消耗,延长无线传感器网络的寿命。     

WSN中基于LEACH的改进路由协议

针对LEACH协议中簇首分布不均匀和节点能量消耗不均衡的问题,为了提高节点能量利用率,延长网络运行周期,提高节点在网络运行过程中的存活率,提出了一种LEACH-NE改进算法。该算法综合考虑节点到基站的距离及节点的剩余能量等因素确定最佳簇首个数,然后通过考虑能量因素来优化簇首选择。仿真结果证明了改进后的路由协议在网络运行周期和网络能量消耗方面优于LEACH协议。     

一种能量均衡的无线传感器网络分簇路由协议

由于无线传感器网络节点能量有限,为均衡无线传感器网络节点之间的能量消耗,提高整体网络的生命周期,针对LEACH协议中簇首选举时未考虑节点剩余能量因素、随机分簇等不足,提出了一种改进的LEACH协议.改进的LEACH协议在簇首选举时,以节点的剩余能量作为重要参考依据,优化节点担任簇首的概率.仿真结果表明,与传统的LEACH协议相比,改进的LEACH协议达到了能量消耗均衡的目标,从而延长了网络的生存寿命.     

一种基于LEACH的改进无线传感器网络路由协议

为了在无线传感器网络(WSN)中降低能耗和提高网络生存期,针对LEACH协议中簇头选举不合理和随机分簇的不足,提出了一种LEACH的改进协议.该协议首先计算无线传感器网络的最佳分簇数量,然后与遗传算法相结合对网络进行分簇,再根据簇中节点的剩余能量等情况选出簇头节点.仿真结果表明,与经典的LEACH协议相比,改进后的协议减少了网络的能量消耗,延长了网络生命周期.     

基于非均匀分簇与路径优化的WSN路由协议

在无线传感网络中,传感节点的能量有限性,使得能量有效利用成为其"热点"问题。针对LEACH协议簇头的随机选择,导致成簇不合理或簇头节点加速死亡,簇首与基站直接通信能量消耗大的问题。提出了一种高能效路由协议UCPO。该协议根据最佳簇头个数划分区域,综合考虑簇内能量消耗和节点剩余能量选择簇头,以多跳方式完成数据的发送。仿真表明,改进协议显著减少整个网络能量消耗,延长了网络的生存周期。     

基于LEACH的WSN簇头优化策略

针对无线传感器网络(WSN)能量和节点分布不均匀的问题,提出一种基于低功效自适应集簇分层(LEACH)协议的WSN簇头优化策略。在二次簇头选择机制下,对保护性能最差的节点进行优化,从大于簇内平均能量的节点中,寻找距离簇内性能最差的节点,将与其最近的节点选为簇头,由此形成簇头间多跳最优通信方式。实验结果表明,该策略能减少节点能量消耗,延长网络生命周期。     

基于多尺寸网格的LEACH协议改进

针对低功耗自适应集簇分层型(LEACH)协议中节点采集的数据存在大量冗余和能量消耗不均衡问题,提出一种能量高效路由协议MDG-LEACH。该协议基于虚拟网格和多尺寸网格选取活跃节点,采用综合考虑节点剩余能量和空间分布情况的簇头选择机制,簇头与基站之间根据动态规划方法建立最短传输路由树进行数据传输。仿真结果表明,与LEACH协议以及单剑锋的LEACH改进协议(计算机技术与发展,2013年第2期)相比,MDGLEACH协议在均衡节点能量消耗和延长无线传感器网络寿命方面有了较大提高。     

基于能量高效的无线传感器网络LEACH协议改进

针对无线传感器网络节能问题,详细分析了经典分簇协议——LEACH,在其基础上针对LEACH的不足进行改进,提出了一种能量高效的分簇路由协议。该协议在簇头选举的算法中纳入节点剩余能量作为参数,提出各簇独立进行的簇头轮换机制,控制簇头在簇中的分布和各簇成员节点数目,并采用基于阈值的单跳与多跳相结合的簇间通信方式。仿真结果表明,改进后的协议较LEACH能够有效节约节点能量,均衡网络各节点消耗,显著延长了网络生存周期。     

传感器网络中一种能量有效的簇头选择机制

针对LEACH算法存在簇头节点个数和位置分布不稳定的现象,在簇头节点的选择过程中,充分考虑簇头节点的残余能量因素,通过设定簇头的能量阈值防止低能量的节点成为簇头。改进的算法解决了LEACH簇头选择算法存在的簇头节点可能能量不足的问题,从而达到均衡网络能量消耗,延长网络寿命的目的。仿真实验采用改进算法的网络与采用LEACH、DCHS以及LEACH-H算法的网络的比较结果,说明改进算法具有更好的收敛性,实验数据表明该算法能最大限度地均衡利用网络的能量,延长无线传感器网络的寿命。     

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.     

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.     

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)

正~~