基于蚁群优化的AdHoc网络生存时间和其他网络性能平衡路由协议

本文提出了基于蚁群优化(ACO)算法的Ad Hoc网络生存时间和其他网络性能平衡路由协议(ABEAR)。协议按需发送人工蚂蚁进行路由发现,综合节点残留的信息素浓度、下一跳节点剩余能量、节点周围链路质量和拥塞情况选择下一跳节点来转发数据包,尽量避开信道使用频率较高的路径,减少了因信道冲突、数据包丢失和数据包重传所造成的能量损失,还缩短了网络传输时延,提高了网络吞吐量。协议还采用跨层机制根据MAC层通信活动情况,在保证网络连通性的前提下使部分空闲节点转入睡眠状态来节省能量消耗。仿真表明,与AODV协议相比,ABEAR协议在网络生存时间、数据包交付率和端到端平均时延方面均有较大改善。     

基于蚁群优化的无线自组织网络能量感知路由协议与参数优化研究

蚁群优化ACO(Ant Colony Optimization)作为一种模拟进化算法,具有信息正反馈、分布式计算和多agent协同的特点,在求解复杂优化问题方面体现出许多优越性。提出基于ACO的无线自组织网络能量感知路由协议ABEAR(Ant-Based Energy-Aware Routing)。协议按需发送人工蚂蚁进行路由发现,根据信息素浓度、节点能量和链路使用情况综合选择下一跳节点来转发数据包,尽量避开信道使用频率较高的路径,还可根据节点通信活动情况将空闲节点转入睡眠状态来节省能量消耗。由于蚁群参数的取值对于ACO算法的性能有着非常重要的影响,因此在分析三个关键参数(信息素挥发系数ρ、信息素权重因子α、剩余能量和链路拥塞指标权重因子β)对ABEAR性能的影响基础上,在NS2平台上进行了仿真实验,对参数优化的效果进行了对比,并总结出了参数值设定的具体步骤。     

无线传感器网络中一种改进的能效数据收集协议

基于连通支配集的虚拟骨干是减少支配节点数量和限制路由搜索空间的关键技术,对于优化无线传感器网络生命起到重要作用。ViTAMin协议不但能通过关闭一些非必要节点产生虚拟骨干,而且能将采集的数据沿着距离基站能耗最低的路径进行发送,以节省能量。针对ViTAMin可能会产生非连通网络且支配节点能耗不均衡的问题,提出了一种基于虚拟骨干的能效数据收集协议EEVB。理论分析证明,EEVB能够以O(n)的时间与信息复杂度构造连通支配集,仿真实验进一步证实EEVB能够以较小的能耗开销构建规模较小的连通支配集,并有效延长网络的生命时间。     

基于节点编码感知的机会转发路由协议

针对现有考虑节点编码机会的编码感知路由协议Ex CAR(a coding-aware routing protocol termed extended coding aware routing)在无线链路不稳定的情况下转发节点集内的节点在计算编码机会时可能产生误判,以及在转发节点集内选择最优编码节点时需要交换大量的数据包缓存信息会导致较大的端到端时延和网络开销等问题,提出一种适用于多跳无线网络的节点编码感知机会转发路由协议NAOFP(node network coding aware opportunistic forwarding routing protocol)。NAOFP协议通过引入基于侦听概率的附加ID信息添加机制和转发节点集的最优转发节点选择机制,提高了网络吞吐量和编码包的解码成功率,减小了数据包的平均端到端时延。仿真结果表明,与Ex CAR协议相比,NAOFP协议在网络吞吐量、平均端到端时延、编码包的解码成功率等方面的性能均得到了有效的改善。     

基于区域划分的连通支配集协议

针对规模较大、节点分布密集的无线传感器网络容易产生冗余数据包以及信号冲突,导致过多的节点能量消耗,加速死亡过程等问题,在深入研究现有的分布式连通支配集构造算法的基础上,提出基于区域划分的连通支配集协议——RPMPR协议.RPMPR协议中每个节点针对网络拓扑信息,对邻居节点进行区域划分,在各区域内选择中继转发节点集,并以节点的度作为选择支配节点的依据,构建覆盖全网的连通支配集.仿真实验结果表明,RPMPR协议充分考虑网络拓扑信息,显著减小连通支配集规模,同时支配节点分布更为均匀.     

无线传感器网络极小连通支配集算法的改进

无线传感器网络中,基于极小连通支配集的虚拟骨干网的构建使得路由搜索空间集中在支配节点之间,能够有效节省网络资源,减少冗余转发节点。首先提出连通支配集的数学模型。基于WL算法,提出改进的极小连通支配集分布式算法。仿真结果表明,改进算法求得的连通支配集较小,可为无线传感器网络中的路由协议提供通讯基础。     

适用于数据链网络的改进动态源路由协议

动态源路由(DSR)协议在数据链网络中的缺点是控制开销过大,导致低网络带宽时容易发生拥塞,根据数据链网络节点的群组移动特性,提出了一种基于位置估计的协议改进方法。将节点位置信息应用到协议中,分别从路由发现和路由维护两个方面减少协议的控制开销,当与下一跳节点链路断开时,通过依次搜索本节点到后续节点的路由来提高数据包的拯救概率。仿真实验结果表明,改进算法有效地控制了协议开销,同时又减小了数据包丢弃的概率。     

基于萤火虫群优化的Ad Hoc网络路由协议

针对Ad Hoc网络拓扑结构多变、网络生存时间受限及数据包分组传输效率低下等问题,本文借鉴萤火虫群优化算法的思想,提出了一种基于萤火虫群优化的Ad Hoc网络路由协议。路由协议用萤火虫优化算法的荧光素强度的更新规则与无线自组网络中的节点移动速度、拥塞程度、节点剩余能量及节点间的距离等因素相互映射,改进萤火虫群优化算法中的搜索萤火虫、驻留萤火虫及回溯萤火虫用于完成Ad Hoc网络中路由协议的路由发现、路由选择及路由维护等过程,整个协议无须传送大量的控制分组,即可实现Ad Hoc网络的稳定。仿真实验结果表明,与AODV及基于蚁群优化的路由算法AntRouting协议相比,本文所提出的路由协议在端到端延时、分组数据传输率及网络生存时间上均有良好的性能。     

一种优化链路状态预测的路由协议

针对无人机自组织网络中节点运动快速且拓扑变化频繁的特点,提出一种优化链路状态预测的路由协议——OLSFR。OLSFR通过对无人机节点运动链路状态进行预测,并定义计算MPR集合的约束性参数以达到路由选路优化和提高性能的目的。仿真实验证明,相比OLSR、DSDV等相关协议,OLSFR能有效改善无人机自组织网络的数据包传递成功率和端到端延时。     

基于多路径蚁群算法的无线传感器网络的路由

针对能量控制在无线传感器网络路由上的特殊要求,为了促使网络节点能量消耗相对均衡,将基本蚁群算法(ACS)应用于无线传感器网络的路由,提出一种基于多路径蚁群算法的无线传感器网络的路由(MACS).该算法利用蚁群的自组织、自适应和动态寻优能力,通过蚂蚁并行地寻找从源节点到达目的节点的最优路径和次优路径,使得网络中的节点不需要维护全局信息,形成多条传榆路径,延长了整个网络的生命期.仿真结果表明,该算法和定向扩散路由(DD)、基本蚁群算法及极大一极小蚁群算法(MMAS)相比,在路由代价和节能方面效果显著.     

European Community policy and the market

Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven.     

一种自适应子融合集成多分类器方法

融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。     

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.     

Explanation and prediction: an architecture for default and abductive reasoning

Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given.     

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.     

Three Process Perspectives: Organizations, Teams, and People

This paper provides the author's personal views and perspectives on software process improvement. Starting with his first work on technology assessment in IBM over 20 years ago, Watts Humphrey describes the process improvement work he has been directly involved in. This includes the development of the early process assessment methods, the original design of the CMM, and the introduction of the Personal Software Process (PSP)^SM and Team Software Process (TSP){^SM}. In addition to describing the original motivation for this work, the author also reviews many of the problems he and his associates encountered and why they solved them the way they did. He also comments on the outstanding issues and likely directions for future work. Finally, this work has built on the experiences and contributions of many people. Mr. Humphrey only describes work that he was personally involved in and he names many of the key contributors. However, so many people have been involved in this work that a full list of the important participants would be impractical.     

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.     

基于复小波噪声方差显著修正的SAR图像去噪

提出了一种基于复小波域统计建模与噪声方差估计显著性修正相结合的合成孔径雷达(Synthetic Aperture Radar,SAR)图像斑点噪声滤波方法。该方法首先通过对数变换将乘性噪声模型转化为加性噪声模型,然后对变换后的图像进行双树复小波变换(Dualtree Complex Wavelet Transform,DCWT),并对复数小波系数的统计分布进行建模。在此先验分布的基础上,通过运用贝叶斯估计方法从含噪系数中恢复原始系数,达到滤除噪声的目的。实验结果表明该方法在去除噪声的同时保留了图像的细节信息,取得了很好的降噪效果。