异构无线网中面向QoS的马尔可夫选择策略

针对移动终端在异构网络环境下,需要在垂直切换过程中进行网络选择的问题,提出一种面向QoS的马尔可夫选择决策算法,通过对算法模型合理化构建过程与异构环境特点的紧密结合、报酬函数的正确定义与求解,可以为用户选择合适的接入网络,最大程度地满足在异构网络环境中用户QoS的长期效益。仿真结果表明,该算法可以有效提高判决水平,改善业务的QoS。     

基于移动互联网的QoS分级自适应策略研究

提出在网络融合时基于实时应急管理的QoS分级自适应策略，用分级映射表的方法建立了移动网与互联网QoS映射的关系，并提出了多业务聚合流的QoS级别选择算法：用接入互联网的网关作为自适应QoS调节的决策节点，由网关监测到的网络负载变化，根据业务流对QoS作出及时调节，使决策更加及时。仿真模拟表明，该策略解决了移动接入网与Internet提供业务的QoS匹配映射问题，可以使传输时延减少至少20％，并能抑制用户盲目扩大自己的需求，避免了用户恶意攻击加重网络负担。     

基于Q学习的异构网络选择新算法

针对异构网络中的多样业务需求,并且为了能够适应网络环境的动态变化,为每一个会话选择一个最合适的网络为其服务同时实现网络负载的均衡,以HSDPA和WiMax构成的异构网络为背景,基于Q学习算法,提出了一种异构网络环境下无线接入网络选择的新算法。该算法在进行网络选择时不仅考虑到网络的负载情况,还充分考虑了发起会话的业务属性、终端的移动性以及终端在网络中所处位置的不同。仿真结果表明该算法降低了系统阻塞率,提高了频谱效用,实现了网络选择的自主性。     

一种面向业务类别的区分权值异质无线网络选择算法

在以满足业务服务质量（QoS）需求为目标的异质无线网络选择问题中,针对不同类别的业务在QoS需求上的差异,利用层次分析法对3GPP定义的四类业务进行了QoS参数相对重要性分析,设定了每类业务的QoS参数权值,然后基于理想值近似性排序算法,提出了一种面向业务类别的区分权值异质网络选择算法。仿真结果表明,区分权值算法相比平均权值算法而言,前者在满足业务QoS需求的同时,能够更合理地选择目标网络,有效地平衡候选网络负载。     

基于动态扫描周期的多属性垂直切换算法

当终端处于动态的异构无线网络环境下,为在减少终端能耗的同时,及时检测到周围可用的无线网络并从中快速选择一个合适的接入网络,提出一种基于动态扫描周期的多属性垂直切换算法。在网络发现阶段根据终端接收到的当前接入网信号强度和终端的移动速度动态调整扫描周期,减少终端接口激活次数。在网络选择阶段采用多属性判决法综合考虑多种网络属性,采用层次分析法和熵权法根据业务类型不同对各参考属性进行权值分配,引入微小阈值对网络进行过滤。仿真结果表明,与现有算法相比,所提算法能够在减少终端能耗的同时,及时地为终端选择出最佳的接入网络。     

基于SDWN的负载感知终端多点关联方案研究

软件定义无线网络（SDWN）是一种控制与转发分离的无线网络架构。该架构可以快速获取全局拓扑并且其可编程性结合资源虚拟化技术可以对网络接入进行动态控制。针对现有WLAN网络接入负载不均衡问题及移动终端与AP硬关联导致的切换速度较慢的问题,基于SDWN架构提出了一种负载感知终端多点关联方案。该方案对SDWN网络架构下的终端接入算法进行改进,采用多点关联技术,即终端在感知AP负载数据后,可关联多个虚拟AP,达到动态分流并提高网络吞吐量的目的。最后在SDWN的开源Odin平台上验证了方案的可行性,实验表明相比无缝切换至另一AP,此方案可改变原有终端与AP接入一一对应的接入关系,根据AP负载动态接入,可有效提升网络吞吐量。     

基于改进多属性判决的异构网络接入选择算法

针对现有多属性切换算法没有考虑所切换的目标网络负载、难以保障网络服务质量的不足,提出基于改进多属性判决的异构网络接入算法。首先,采用万有引力模型简化了复杂多属性判决算法的计算过程,减少了网络接入切换执行时间;其次,在切换执行前,通过加入负载判决模块计算出最优目标网络、次优目标网络负载,从而选出最终切换的目标网络。采用MATLAB和NS2等仿真工具,搭建了WLAN和UMTS融合的异构网络仿真环境。仿真结果表明,算法明显提高了整体网络的负载均衡度和资源利用率,有效降低了移动终端的切换阻塞率。     

网络与终端协同选择及切换机制的研究

提出了一种智能切换机制,用于实现在异构网络中网络与终端的协同选择及切换功能。随着各种业务和应用的发展,异构网络融合是信息和通信技术的必然趋势。根据多接入、多终端等应用环境的要求,采用AHP与URA等多属性决策理论,为用户选择最佳的目标网络和目标终端,并提出相应的智能切换信令流程,包括网络切换、终端切换、网络与终端联合切换方式,最终构建以用户为中心的多终端智能空间,实现个人移动性管理。仿真表明,该智能切换机制可以有效地实现网络和终端的协同选择,并可以保证在异构网络切换QoS性能,为现代服务业的业务及应用的发展提供可靠的理论依据。     

基于模糊多目标决策的两跳中继蜂窝网络切换算法

简要介绍了在集成两跳Ad Hoc和蜂窝网络的结构下,触发网络进行切换的一些因素和两种路由代理发现算法,并且提出了一种新的基于模糊多目标决策方法的切换决定算法。算法从层次分析和模糊综合评价理论的思想出发,结合用户、终端、业务和网络信息,对网络链路的性能进行综合评价,选择出最适合用户业务请求的路径。仿真显示在用户可感知业务QoS下降的情况下,算法可以通过增加QoS的权重而切换到更好的网络链路上,从而为用户提供了“总是最好连接”的服务。     

基于主客观权重判决的异构无线网络接入选择算法

为确保异构无线网络接入选择算法能够从备选网络中选择出性能最优的无线网络,提出一种新的异构无线网络接入选择算法。利用模糊层次分析法计算异构无线网络属性指标的主观权重,并运用粗糙集理论计算客观权重,根据业务需求对主客观权重进行动态调整,以达到最佳的服务质量。实验结果表明,该算法可降低网络切换频率,减少网络阻塞的发生概率,有效均衡网络负载,并能够较好地选择最佳的接入网络。     

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。