异构无线网络环境下的联合网络选择策略

异构无线网络环境下,无线终端可以采用多种接入技术(UMTS、LTE、WLAN等)进行通信.针对异构无线网络中带宽资源受限的问题,提出了一种基于带宽资源分配的网络选择策略.该策略首先以用户的信息传输速率作为目标函数,以带宽资源限制作为约束条件,采用凸优化理论得到最大化的信息传输速率,然后根据获得最大化信息传输速率所需的带宽资源和接入网络可提供的带宽资源,将用户分配到最合适的网络中,可以避免盲目接入造成的资源浪费.与已有的网络选择策略不同,提出的策略以带宽受限情况下最大化整体网络的信息传输速率和带宽利用率为目标.理论分析和仿真实验证明该文提出的网络选择策略可以获得较高的网络吞吐量和资源利用率.     

马尔科夫模型在异构无线网络选择中的应用

研究异构无线网络接入选择问题.选择网上最佳资源连接,由于通信过程存在随机性,单一方法难以确定最优接入网络.为满足异构无线网络选择准确性,提出一种马尔科夫的异构无线网络选择算法.首先选择网络性能指标,然后采用层次分析法确定网络性能指标权重,再通过马尔科夫模型计算每一个网络的期望总同报值,并选择回报值最大的网络作为当前最优接入网络进行仿真.仿真结果证明,相对于传统网络选择算法,马尔科夫算法能够根据用户需求选择到最优接入网络,可以有效地减少切换次数,提高有效吞吐量和降低丢包率,提高了异构性网络选择的准确性.     

基于最优功率控制和马尔可夫链优化的异构无线网络

为了提高异构无线网络的资源利用率以及网络吞吐量,提出一种基于最优功率控制和马尔可夫链优化的异构无线网络,通过建立异构网络模型对异构网络的业务负载情况进行分析,采用有限容量下的最优功率控制方法来使业务能够选择合适的接入网络,并采用基于马尔可夫链来进行网络吞吐量优化,在对不同形式的网络进行速率分配时,采用了多权重优化进行求解最优解,可以降低网络的阻塞情况,提高网络的利用效率.实验仿真结果及分析表明,该算法在提高网络吞吐量、减少网络利用效率上具有较好的效果.     

基于博弈论的异构融合网络接入选择方法研究

各种异构接入网络的无缝融合是下一代网络的显著特征之一,不同网络技术接入形式的多样化使得多网络接口的用户终端可自主选择对用户最为有利的接入网络(或SP,Service Provider)获得互联网服务.文中给出一种面向用户可视化可操作的异种网络接入选择实现机制,该机制采用一种量化接入系统服务质量的统一评价模型及基于最优用户性价比的网络选择决策方法,同时依据不同接入网络之间的合作与非合作关系以及SP与用户之间的竞争关系,引入博弈论方法建立网络价格策略的两种博弈模型,通过求解模型的纳什均衡价格及共谋价格,确定网络优化定价机制.仿真结果比较了异构网络融合环境下的各接入网络在非合作和合作博弈模式中的优化定价机制及获得的收益特性,并比较了不同博弈场景下用户选择接入网络的性价比.     

基于博弈论的多用户双向选择卫星异构网络算法

针对目前卫星异构网络选择算法较少且大多只考虑用户或网络一方满意度的问题,综合衡量用户和网络双方利益,提出了一种基于博弈论的卫星异构网络多用户接入选择算法。该算法通过在用户与网络之间建立博弈模型,利用层次分析法分别计算各决策因素权重,得到各类用户与网络各自可供选择的最优网络集或用户集排序,并通过双方博弈进行双向选择。仿真结果表明,该算法能够较好地解决多用户接入卫星异构网络问题,取得了网络与用户双赢。     

考虑负载均衡与传输速率的异构网络接入控制

针对异构无线网络中存在的负载不平衡和传输速率受限的问题,采用改进分解的多目标进化算法(MOEA/D)对目标函数求解,提出一种改进的业务接入控制优化方法.建立异构网络模型,构造双曲线聚合函数,通过控制权重向量与坐标轴的距离,调整个体的支配范围,根据适应度的变化对邻域值大小和变异概率进行自适应调节,提高算法的收敛性、多样性和全局搜索能力.实验结果表明,改进算法应用在异构无线网络的业务接入控制中能够获得更大的系统传输速率,更好地保证网络间的负载平衡,优于其它两种比较算法,使网络资源得到更优的配置.     

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。     

异构网络中基于博弈的多宿主用户带宽分配算法

针对异构无线网络中的带宽分配问题,将网络间的带宽分配模型转化为非合作博弈模型,提出一种基于非合作博弈论的动态带宽分配（ NCRA）算法。首先,根据用户的带宽需求,并充分考虑当前各种不同网络的负载因素,设计一种基于网络能力动态为用户分配带宽的效用函数;然后,通过证明效用函数为凹函数来验证网络间非合作博弈纳什均衡的存在性,并获得网络间的最佳带宽分配策略;最后,通过仿真实验,验证所提出算法的性能。     

异构无线网络选择算法的仿真研究

研究异构无线网络选择问题.异构无线网络选择是下一代无线网络的关键技术及多网融合的基础,决策指标相当多,传统判决指标权重方法具有片面性,无法为用户提供最佳网络选择服务.为了提高异构无线网络选择的准确性,把层次分析和灰色关联评价法结合起来,提出一种组合的异构无线网络选择算法.通过对影响网络选择的指标进行分析,用层次分析法和方根法确定网络决策指示的权重,最后对备选网络进行灰色关联选择,选择最优接入网络.仿真结果证明,相对于传统网络选择算法,更加客观准确地选择与用户需求最佳匹配网络,并降低用户的接入成本,从而可以满足用户的业务需求,为异构无线网络设计提供了参考.     

基于声望模型的联合呼叫接纳控制算法

为了弥补异构无线网络中呼叫接纳控制研究场景的局限性,降低终端选择接入网时的盲目性,将研究场景从两个接入网延伸为多个接入网,提出一种基于声望模型的联合呼叫接纳控制算法。将声望模型应用于网络选择过程,增加了网络反馈机制。在用户侧,终端根据网络声望值大小选择接入网;在网络侧,采用动态带宽分配和缓冲队列策略来提高接入成功率。仿真结果表明,该算法有效降低了新呼叫阻塞率和切换呼叫掉线率。     

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