可用带宽自适应判定算法的研究

在理论分析和实验研究的基础上,提出可用带宽自适应判定算法。该算法采用自适应周期性探测流技术,通过周期性地发送包列,自适应地判断延迟趋势并反馈探测值,以准确快速地实现可用带宽的测量。仿真实验结果表明,该算法可行、有效,是一种对受测网络的影响小、低测量代价的端到端可用带宽测量方法。     

基于自拥塞理论的传输控制算法设计与实现

对可用带宽测量算法SLOPS进行分析,针对其探测流量过大,测量结果易受背景流量影响等缺陷,设计实现了一种基于自拥塞理论的数据传输控制算法DTCA(Data Transmission Control Algorithm)。该算法通过发送轻量级的探测报文来探知当前网络状态,进而调整数据发送速率,以达到充分利用带宽资源的目的。测试结果表明,该算法能够自适应的调整数据发送速率,提高带宽利用率。     

网络可用带宽测量算法的改进

重点研究了网络端到端可用带宽的测量方法,对现有的基于自拥塞理论的可用带宽的测量方法Pathload进行了简要分析.针对该方法的缺点提出了改进的可用带宽测量算法,改进的可用带宽测量算法采用周期流组到达目的端的速率代替周期流的发送速率,能快速测量网络的可用带宽,测量准确性更高,降低了测量开销.NS-2上的模拟实验结果表明,该方法是可行的和有效的.     

一种速率自调节可用带宽测量算法

可用带宽是网络路由、网络服务质量、流量工程等方面的一个关键参数。目前很多研究方法都基于PGM模型和PRM模型,但这两种方法大都假设背景流量速率为固定比特流,不适用于低带宽的测试。提出一种端值自调节可用带宽测量算法,该算法充分考虑了低链路带宽的情况。通过对排队延时的处理、探测分组列速率端值自适应调节,实现了端到端可用带宽快速准确的测量。实验结果表明,该算法具有良好的测量效果,尤其在低带宽条件下较其它同类算法提高了测量准确性,加快了测量速度并减小了对网络的影响。     

面向实时应用的可用带宽自适应测量方法*

设计了一种快速的自适应端到端路径可用带宽测量方法——AABw。它具有以下几个特点：针对背景流量突发性和负载状况,自适应地动态调整探测包串（probing packets train）的长度;改进了探测包串发送速率的调节方法,既保证了算法快速收敛的特点,又更能适用于背景流量突发的情况,提高了实时带宽测量的精确度;改进了判断单向延时趋势的算法。仿真实验表明,该算法能准确快速地测量出端到端可用带宽,适用于实时应用环境。     

基于自拥塞理论的数据传输控制算法设计

基于自拥塞理论的网络带宽测量技术存在探测流量过大,易拥塞网络等缺点,因而在网络传输中的应用具有一定局限性.针对这些不足,提出一种新的数据传输控制算法ProDTCA.ProDTCA利用数据包单向延迟特性,通过源端定时发送轻量级探测流,估测带宽占用状况,动态的调整数据发送速率.仿真结果表明ProDTCA可以快速的调整数据发送速率,避免网络拥塞,防止数据包丢失,达到对网络带宽的高效利用.与传统基于自拥塞理论的带宽测量方法相比,ProDTCA能够自适应的调整数据发送速率,有很高的工程应用价值.     

网络主动带宽测量算法设计

本文基于Cruz流量模型.通过主动检测单向时延连续上升的概率.推断探测速率与端到端可用带宽之间的关系,提出一种网络可用带宽主动测量算法PathPCQ.NS2仿真显示,PathPCQ算法测量精度和效率都优于现有的带宽测量工具Pathload.     

WPathload:一种改进的可用带宽测量方法

可用带宽是网络的重要资源,对其准确的估计与测量是流量工程和网络监测等必须解决的问题,但对它的实际测量存在许多困难.针对Pathload可用带宽测量方法存在收敛慢、开销大的问题,提出了一种Pathload可用带宽测量的改进方法(WPathload).该方法基于时延变化的统计规律,改进发送速率调整算法,并采用周期流组到达目的端的速率代替周期流的发送速率,更新可用带宽上界,从而加快收敛速度,降低测量开销.实验结果表明,改进后的方法能快速反映可用带宽的变化,增强了跟踪带宽变化的能力.     

可用带宽测量的TCP友好性仿真分析

以发送包链为特征的可用带宽测量会产生较大探测流量而影响网络性能.设计了三种具有不同包链长度的测量模式模拟典型的包链发送策略,仿真分析了可用带宽测量的TCP友好性.发现可用带宽测量的TCP友好性并不理想,原因在于探测流会增大TCP流的时延及丢包而触发TCP的拥塞控制机制.仿真中最大降低TCP数据传输量近16%;且太长或过短的包链发送策略对TCP性能有更大影响.在Pathoad这一典型可用带宽测量工具中的分析结果进一步验证了该结论,且得出了Pathload的应用策略.     

一种提高端到端数据传输速率的方法及系统

成果描述：本发明涉及一种提高端到端数据传输速率的方法及系统。该方法的思路为：利用源节点和目的节点之间的多条间接路径和直接路径,在每条路径上创建多个TCP连接,在路径选择过程中,记录所有TCP连接的耗时,关闭连接超时的TCP连接;接收方向所有建立的TCP连接发送探测数据包;中转服务器收到的探测数据包转给发送方;发送方根据探测包到达的先后顺序决定采用哪些TCP连接并沿探测数据包走过的路径向接收方分块传递文件。     

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。     

How do children do mathematics with LOGO?

Abstract  This paper considers some results of a study designed to investigate the kinds of mathematical activity undertaken by children (aged between 8 and 11) as they learned to program in LOGO. A model of learning modes is proposed, which attempts to describe the ways in which children used and acquired understanding of the programming/mathematical concepts involved. The remainder of the paper is concerned with discussing the validity and limitations of the model, and its implications for further research and curriculum development.