具有拥塞感知的Mesh负载均衡路由策略

为解决无线Mesh网络传输的负载拥塞问题,综合考虑网络的负载水平以及节点状态信息,提出了基于拥塞感知的负载均衡算法。在传递报文时,根据网络实时的负载状态信息,选择负载水平较低的路径作为传输路径,使得数据流尽可能地分散到负载水平较低的节点上,从而有效抑制网络拥塞情况的发生,充分利用网络资源。使用OMNet++仿真软件进行测试,结果表明该算法能够有效降低网络的丢包率,并明显提高网络的吞吐率。     

考虑过载状态和失效概率的航空网络级联故障模型

为提高突然事件引起的级联故障对航空网络破坏程度的评估可信性,考虑到机场节点对负载的冗余能力,即如果在一定的空间范围内出现过载,节点不会立即失效,而是具备一定的超额负载处置能力,提出一种考虑过载状态和失效概率的航空网络级联故障模型。该模型首先在传统的“负载-容量”Motter-Lai级联故障模型中增加了过载系数、权重系数、分布系数和容量系数,其次以过载状态和失效概率来描述网络节点的冗余容量特性,并对失效节点和过载节点采用不同的负载重分配策略,使模型更贴合航空网络实际。理论分析和仿真结果表明：在一定范围内提升过载系数有助于降低级联故障的影响,然而提升到一定程度后改善效果不明显;模型中的各参数存在最优区间,可以使航空网络保持较好鲁棒性的同时,花费较小的构建成本,据此对航空网络资源进行优化配置,可以提升网络对级联故障的抵御能力。     

考虑节点过载的碳排放空间关联系统级联失效模型

为提高突发事件级联失效对现实碳排放关联系统破坏程度的评估可信性，在传统复杂网络的"负载-容量"级联失效模型基础上，考虑个体成员对负载的冗余能力，提出一种过载失效概率，构建了考虑节点过载状态的级联失效模型，并基于节点特性提出了6种过载节点负载分配策略。仿真结果表明：在过载节点负载分配策略中，综合分配策略整体上较优，能够有效控制级联失效的规模，增加网络鲁棒性；在一定范围内提升过载参数有助于降低级联失效的影响，但提升到一定程度时改善效果不明显；在不同负载分配策略下，剩余系数存在一个最优值，容量可调参数存在最优区间，可以使碳排放关联网络保持较好鲁棒性的同时，花费较小的构建成本，其中紧密度分配策略对应的网络构建成本较高。     

加权网络的交通动力学研究

提出一种综合考虑网络边权和节点空闲度的路由策略,该路由搜索策略具有一可调参数 ,应用该策略对BBV加权网络上的数据传输进行研究。通过大量的数值仿真发现,当 时,网络具有最大的通信能力、较小的平均传输时间和最小的网络负载。与基于局域边权信息的路由策略相比,该策略可以提高网络通信能力,在拥塞状态下减小网络负载。对于加权网络的拥塞控制具有一定指导意义。     

考虑约束参数切换的小蜂窝LTE移动负载自适应均衡

针对因用户设备移动性和小区覆盖率造成的网络负载周期性不平衡问题,引入小蜂窝网络以支持高数据率服务和密集部署,提出一种自适应网络负载状态并考虑负载估计的小蜂窝网络移动性负载平衡算法。该算法根据过载单元和相邻单元调整进行参数切换,其资源利用取决于信号质量和所连接用户设备在长期演进网络(LTE)中的流量需求,并定义资源块利用率作为单元负载的度量,根据网络负载情况使用自适应阈值来确定过载单元。为避免性能振荡,考虑移动负载对网络的影响,进行负载均衡过程设计。最后通过系统级仿真评价了该算法在不同环境下的性能,仿真结果表明,该算法在网络间提供了更均衡的负载(即小区间的标准差较小),比以前的算法具有更高的网络吞吐量。     

多跳无线传感器网络自适应链路层FEC/ARQ控制策略

提出一种用于多跳无线传感器网络数据传输的数据链路层自适应混合FEC/ARQ控制策略,以提高无线传感器网络通信的可靠性.该策略基于Kalman滤波器预测当前的网络状态,根据混合FEC/ARQ能耗规律和特点,自适应地调整FEC参数n.此外,发现ARQ能耗与重传策略无关,而与网络状态有关.数学分析和仿真验证均表明,该策略能有效降低多跳无线传感器网络的能量消耗,显著地提高数据传输的可靠性.     

无线传感器网络中一种基于分簇的能量高效虚拟MIMO传输策略

协作式MIMO技术被认为是传感器网络中有效的节能解决方案之一.针对中小规模传感器网络设计了一种基于分簇的能量高效的协作式虚拟MIMO传输策略(ECCM).在考虑了分布式STBC编码信道训练开销的情况下,分析了该传输策略的系统总体能耗.基于该能耗模型,建立了一种基于端到端的全网能耗最优化模型,并用该模型来求解最优的虚拟MIMO域(分簇)个数、协作节点(虚拟天线)个数以及传输速率等网络通信参数.仿真结果表明,通过选取最优协议参数,即使考虑到电路能耗和信道训练开销,ECCM策略也能显著降低节点传输能耗,延长网络寿命.     

无线传感器网络自适应链路层FEC控制策略*

提出一种适用于无线传感器网络的自适应链路层FEC控制策略。该策略基于Kalman滤波器预测当前的网络状态,在数据链路层采用FEC控制机制,根据FEC能耗分析的自身特性自适应地调整FEC参数n,以便改善无线传感器网络的通信性能,并建立单跳无线传感器网络模型和能量模型。数学分析和仿真验证表明,该策略能够有效地提高无线传感器网络数据传输的可靠性,降低无线传感器网络的能量消耗。     

基于路由器解析式模型的NoC网络性能分析方法

建立一种高效的片上网络(NoC)性能分析方法对NoC早期的系统设计分析具有重要的指导意义.首先从NoC路由器工作原理出发,对报文传输中的各种阻塞现象进行分析,建立了基于M/G/1/N排队系统的路由器模型;然后提出NoC网络性能分析算法,并且给出了传输延迟、饱和吞吐率等参数的解析表达式.与时钟精度仿真结果比较表明,该方法分析误差约为6.9%,但分析效率提高了约200倍.该方法适用于指导程序NoC拓扑映射,在获取最优映射方案同时,可有效地挖掘网络通信瓶颈.     

SDN多控制器网络中基于交换机迁移的动态负载均衡策略

针对多控制器SDN网络环境下的负载均衡问题,论文提出了一种基于交换机迁移的动态负载均衡策略,共分为三个实施阶段:首先通过动态信息采集算法(DIA)收集各控制器间的负载信息,以决定需要实施交换机迁移算法的过载控制器;随后依据论文定义的迁移域及迁移交换机选取算法(MSS)决定迁移目标控制器以及需要迁移的交换机;最后依据交换机迁移协议完成交换机迁移,实现多控制器下的负载均衡.仿真实验结果表明负载均衡后SDN网络中交换机的吞吐率显著提升,且各控制器负载逐渐趋于均衡.     

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.     

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.     

Only connect: teaching, technology and telesis

Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained.     

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