一种可自维护无线网络拓扑最小能量特性的分布式拓扑控制算法

由节点的位置和传输范围确定的无线网络拓扑结构对网络的性能有着重大的影响.拓扑控制通过调节节点的传输功率能够优化网络的性能,减少节点的功率消耗,延长网络的生存时间.文中提出一个分布式的拓扑控制算法,由该算法产生的拓扑结构具有最小能量特性,并且在网络的组成发生动态变化时,算法可以以响应的方式维护全网的连通性和全局的最小能量特性.该算法不仅适用于同质的无线Ad Hoc网络,也适用于异质的网络.仿真研究表明,提出的算法在平均节点度、传输功率的效率以及响应拓扑变化的平均节点数等方面均优于基于直接传输区域的拓扑控制算法.     

一种建立可自维护且具有最小能量特性的无线网络的分布式拓扑控制算法

由节点的位置和传输范围确定的无线网络拓扑结构对网络的性能有着重大的影响.拓扑控制通过调节节点的传输功率能够优化网络的性能,减少节点的功率消耗,延长网络的生存时间.文中提出一个分布式的拓扑控制算法,由该算法产生的拓扑结构具有最小能量特性,并且在网络的组成发生动态变化时,算法可以以响应的方式维护全网的连通性和全局的最小能量特性.该算法不仅适用于同质的无线Ad Hoc网络,也适用于异质的网络.仿真研究表明,提出的算法在平均节点度、传输功率的效率以及响应拓扑变化的平均节点数等方面均优于基于直接传输区域的拓扑控制算法.     

AdHoc网络基于能量均衡的拓扑控制算法研究

为了延长无线AdHoe网络的生存期,降低节点传输过程中的功率消耗,该文提出了一种基于能量均衡的分布式拓扑控制算法,通过引人综合反映能量消耗及剩余能量两方面因素的路径权值函数,根据节点剩余能量的实时变化动态优化网络的拓扑结构。仿真结果表明,算法可以构建具有连通性的网络拓扑结构,与其它算法相比,能够均衡整个AdHoc网络节点的能量,显著地延长网络的寿命,从而保证网络长时间的可靠运行。     

无线自组网基于移动预测和能量均衡的拓扑控制算法研究

为了延长无线Ad hoc网络的生存期,降低节点传输过程中的功率消耗, 提出了一种基于能量均衡和节点运动的分布式拓扑控制算法,它使用能够后衡量节点能量损耗量和当前能量值以及根据节点运行方向和速度来评价当前链路稳定状态的路径权值函数, 根据节点剩余能量的实时变化动态优化网络的拓扑结构。仿真结果表明,算法可以构建具有连通性的网络拓扑结构,与其它算法相比,能够均衡整个无线自组网节点的能量,优化网络吞吐率、端到端时延并显著地延长网络的寿命,从而保证网络长时间的可靠运行。     

基于多目标函数的电网拓扑关系约束规则的优化算法

用现有约束规则优化算法得到的电网拓扑结构无法获取其中环和根节点之间的连通路径，在寻找路径过程中功率损耗较大。为了解决这一问题，设计一种基于多目标函数电网拓扑关系约束规则的优化算法。应用小世界网络构建电网拓扑结构模型，求得幂律分布曲线，建立变电站来减少功率损耗；将有功网损最小、节点电压偏移最小作为目标函数，获得功率平衡方程，建立约束规则；采用粒子群算法求解最优参数，完成基于多目标函数的电网拓扑关系约束规则优化算法的设计。测试结果表明设计的优化算法能够获取电网结构的所有环和所有根节点之间的连通路径，功率损耗为11.31 kW,减小了功率损耗。     

线型无线传感器网络中一种联合优化中继节点选择策略

在无线传感器网络中,时延与功耗性能往往是一对不可兼得的指标,如何优化和平衡这两个指标是路由和MAC算法中的难点.线型无线传感器网络由于拓扑结构的线型性,功耗-时延的均衡问题显得更加突出.基于线型无线传感器网络拓扑模型,理论分析了能耗最优传输距离,然后基于节点剩余能量,构建联合优化目标函数.进一步地,将数据包类型在时间敏感性方面分为紧急数据包和普通数据包,并相应调整发射功率,以便在当前通信范围内找到最优下一跳中继节点.最终提出了一个功率可调的时延-能耗自适应优化中继节点选择算法(LEARS).通过仿真实验将该算法与经典及类似算法比较,LEARS能够在保证紧急数据包传输实时性的同时,进一步降低网络的整体功耗,延长网络的生命周期.     

移动Ad hoc网络中基于拓扑控制的节能算法

如何降低节点能耗,延长节点生存时间是移动Ad hoc网络的一个研究热点,对此提出了一种基于拓扑控制的节能算法ECA/TC（Energy Conservation Algorithm with Topology Control）。该算法在RNG图的基础上,采用邻节点消除机制,有效降低了节点的传输功率及广播消息在网络中的转发次数。仿真结果显示该算法具有较好性能,能够提高网络能效。     

蜂窝网络分布式中继选择算法

针对蜂窝网络中的功耗优化问题,研究了如何最小化两跳中继蜂窝网络的系统总功耗。首先根据信道传输功率的闭合表达式得到满足信道最小中断概率情况下的最优链路传输功率,然后通过使用基于Acknowledgement的分布式拍卖算法(DAA-ACK)和改进的分布式拍卖算法(IDAA)帮助用户节点选择合适的中继基站。仿真结果显示,这两种算法仅需要用户节点与邻居中继基站交换少量信息,并可通过有限次迭代快速选择出使系统总功率最小的中继节点。     

基于工作周期优化的能量采集节点的功率控制

在无线传感网络WSNs(Wireless Sensor Networks)中,节点受到能量限制,因此,需通过功率管理技术有效地使用电池.而能量采集是补给电池能量的有效方式.为此,针对能量采集节点,提出功率控制算法,记为CLPM-PTPC(Close-Loop Power Manager-Predictive Transmission Power Controller).CLPM-PTPC算法是通过联合工作周期的优化和传输功率控制,实现节点功率的管理.CLPM-PTPC算法先利用闭环功率管理CLPM(Close-Loop Power Manager)调整传输任务的工作时期,再依据功率控制器PTPC(Predictive Transmission Power Controller)调整发射功率,使得传输功率能够实时地依据无线信道环境调整.实验数据表明,与基于固定传输功率算法相比,CLPM-PTPC算法的能量效率提高了约15％.     

Ad Hoc 网络中改善拓扑控制性能的移动控制算法

在无线Ad Hoc网络中,拓扑控制算法能够使节点的传输功率小于最大传输功率,从而可以节省网络能量,提高网络容量.由于节点分布的随机性,在节点较为稀疏的区域,拓扑控制算法存在着局限性,因而提出了移动控制算法来改善拓扑控制算法的性能.在保证网络连通性的前提下,算法首先根据收集到的信息,通过构造网络最小生成树确定较长的通信链路,并移动网络中的部分节点使这些链路缩短,从而显著减小网络中较大的通信半径,提高了拓扑控制的性能.仿真实现了PMST-P,PMST-UV和LMST-LUV这3种移动控制算法,并对它们的性能进行了讨论和相互比较.     

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)

正~~     

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