一个提高WiMax服务质量的带宽分配调度算法研究

随着接入网络作为连接用户终端与核心网络的纽带的倍受关注,用户越来越关注数据传输的QoS(服务质量)问题。在IEEE802.16协议的MAC层定义了比较完善的QoS机制。但QoS机制中的核心问题,带宽调度算法,协议没有作出明确的阐述和定义。该文在已有典型算法基础上,吸收、采纳了已有算法中适合于IEEE802.16协议的带宽调度的方法,并结合IEEE802.16协议关于QoS的定义,提出了一个针对IEEE802.16协议的PMP(点对多点)模式下集中式的带宽分配调度算法。并在NS2模拟环境下对算法进行了测试。     

基于IEEE 802.16的接纳控制机制

分析IEEE 802.16的QoS机制,针对其没有详细规定接纳控制算法的情况,结合协议中定义的业务类型QoS特性,在信令交互机制下,提出一种基于优先级的动态带宽分配接纳控制机制。仿真结果表明,与预留带宽的固定带宽分配机制相比,采用该机制后,系统的切换连接掉线率、新增连接的阻塞率和带宽利用率得到改善。     

一种IEEE 802.16宽带无线接入系统的QoS架构

IEEE 802.16 MAC协议虽然对各类业务的QoS提供支持,却没有定义完整的QoS保证机制.本文通过分析IEEE 802.16现有的QoS架构,提出了一种具体的QoS架构,并对相应的调度算法进行了分析.仿真结果表明,该架构能够对实时业务提供较好的支持,同时维持其它业务的带宽在可接受的范围之内.     

IEEE 802．16协议中上行带宽分配机制研究

802.16是新一代宽带无线接入的标准。标准中明确定义了在MAC层实现QoS的机制,例如:MAC层的通信是基于连接的;将上层业务流根据QoS的要求进行分类等。但是标准对上行带宽的分配机制却未加以定义。我们就这个问题进行了研究,并提出了一种有效的上行带宽分配机制。     

一种基于模糊逻辑的多媒体组播准入控制机制

组播呼叫准入控制(CAC)是下一代网络（NGN）QoS的关键问题,在分析已有CAC机制的基础上,提出一种基于模糊逻辑的组播准入控制机制(FMAC),以服务质量、网络拥塞状态参数、可用容量和等效带宽作为模糊输入,经过模糊推理判断是否接受新的组播呼叫。仿真结果表明,FMAC在保持高的网络利用率的同时,能满足用户的QoS要求,并能保持较低的阻塞率,具有扩展性好、实现简单的特点。     

无线自组网络QoS流的准入控制和流量控制

作者曾提出一个QoS路由和准入控制机制－QDSR,并且在小规模实时视频传输实验床上实现了这些方案。虽然QDSR的准入控制只保证每个节点有足够的可用带宽给准入的所有流使用,但并不保证每个流在较小的时间尺度上得到请求的带宽。为此,作者对QDSR的准入控制机制进行了改进并增加了流量控制机制,以满足实时应用的QoS需求。在NS2仿真环境中实现了QDSR以及对QDSR的改进。仿真结果表明,改进机制改善了QDSR的视频流的传输质量,较好地提高了视频流的吞吐率和投递率,减小了数据包的端到端延迟,并且能很好地满足包括视频传输在内的多种业务的传输需要。     

基于动态服务门限的准入控制算法

802.16协议是一种定位于无线城域网的宽带无线接入协议,相应的QoS保证机制如准入控制、分组调度等均在协议中并明确定义.在静态服务门限的准入控制算法基础上进行改进,提出了一种基于动态服务门限的准入控制算法,该方案可以根据业务的阻塞率和丢包率来调整接入门限.通过仿真结果可以看出,该算法不仅能体现业务的优先级,还体现了自适应性和公平性.     

无线网络基于掉线概率的多业务准入控制的性能评估

无线网络是用户自由获得多种服务的主要方式，而无线网络的准入控制方法是保证各种业务的QoS以及无线信道的利用率的关键因素。利用多维Markov过程研究了业务带宽需求时变的状况下基于QoS的多业务准入控制的性能(掉线概率、阻塞概率、信道利用率)，通过数值结果比较了无准入控制下和基于预约的准入控制方法的性能。     

语音WSN的QoS路由和准入控制研究

语音无线传感器网络(WSN)数据量大、处理任务复杂,针对其中的服务质量(QoS)保障问题,总结WSN中的QoS路由协议和准入控制的研究进展,认为准入控制可根据网络拓扑结构分为平面准入控制和分簇准入控制,并针对语音无线传感器网络,提出一种将准入控制和QoS路由相结合的方法,从而提高语音传输质量。     

IEEE802.16中基于自适应信道预留的呼叫接入策略

呼叫接入控制（CAC）在宽带无线接入（BWA）服务质量（QoS）中起着非常重要的作用。对无线城域网中IEEE802.16复杂的QoS定义,该文提出了一种在IEEE802.16中基于自适应资源预留的呼叫接入控制策略（AR-CAC）。该策略根据UGS负载和信道利用率为其自适应预留信道,同时考虑了IEEE802.16业务的带宽特性。仿真结果表明,该策略在硬切换呼叫切换失败概率不变的情况下降低了高优先级服务的呼叫阻塞率,同时增大了系统的吞吐量。     

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.     

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。     

Avoiding semantic and temporal gaps in developing software intensive systems

Development of software intensive systems (systems) in practice involves a series of self-contained phases for the lifecycle of a system. Semantic and temporal gaps, which occur among phases and among developer disciplines within and across phases, hinder the ongoing development of a system because of the interdependencies among phases and among disciplines. Such gaps are magnified among systems that are developed at different times by different development teams, which may limit reuse of artifacts of systems development and interoperability among the systems. This article discusses such gaps and a systems development process for avoiding them.     

Designing economic np control charts: A programmed simulation approach

This paper presents control charts models and the necessary simulation software for the location of economic values of the control parameters. The simulation program is written in FORTRAN, requires only 10K of main storage, and can run on most mini and micro computers. Two models are presented - one describes the process when it is operating at full capacity and the other when the process is operating under capacity. The models allow the product quality to deteriorate to a further level before an existing out-of-control state is detected, and they can also be used in situations where no prior knowledge exists of the out-of-control causes and the resulting proportion defectives.     

The development of robot art

Going through a few examples of robot artists who are recognized worldwide, we try to analyze the deepest meaning of what is called “robot art” and the related art field definition. We also try to highlight its well-marked borders, such as kinetic sculptures, kinetic art, cyber art, and cyberpunk. A brief excursion into the importance of the context, the message, and its semiotics is also provided, case by case, together with a few hints on the history of this discipline in the light of an artistic perspective. Therefore, the aim of this article is to try to summarize the main characteristics that might classify robot art as a unique and innovative discipline, and to track down some of the principles by which a robotic artifact can or cannot be considered an art piece in terms of social, cultural, and strictly artistic interest. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

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.     

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.     

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。     

基于QTE的蒙古文显示机制研究与实现

蒙古语言是中国蒙古族使用的通用语言,由于蒙古文区别于其他文字的书写方式和其自身变形机制等特点,在很多通用的文字处理引擎中都不被支持。在嵌入式产品开发与应用领域中Linux加QTE已经成为流行方式。该文给出了一种在QTE环境上实现基于标准Unicode的蒙古文点阵显示和变形算法, 并自定义了支持蒙古文的QTE组件,扩展了QTE功能,为在Linux加QTE方式的嵌入式体系结构中处理蒙古文提供了一种解决方法。