基于RTP的MPEG-4视频传输和多媒体同步

在RTP协议原理和MPEG-4编码特性的基础上,提出了适用于MPEG-4视频传输和多媒体同步的算法.利用RTP/RTCP端到端的反馈机制实现流量控制、拥塞控制以及媒体同步控制,使整个传输过程充分利用带宽,而不引起网络拥塞;同时保证在线播放时有良好的视觉质量又满足实时播放的要求.     

实时视频传输的反馈拥塞控制策略

提出了RTP/UDP/IP的视频实时传输体系结构。采用基于实时传输协议（RTP）和实时传输控制协议（RTCP）的反馈拥塞控制算法，控制发送端视频编码器输出的比特率，以使得整个基于IP的网络视频传输系统既能充分利用网络带宽又不引起网络拥塞，从而减少时延，降低丢包率，为视频数据的接收者提供一个较好的图象质量。     

基于RTP的h.264无线视频传输和Qos控制

本文在RTP协议原理和H264编码特性的基础上,提出了适用于H264无线视频传输结构.利用RTP/RTCP端到端的反馈机制实现流量控制、拥塞控制以及H264在视频编码层和网络提取层的错误恢复措施.使整个传输过程在提供良好的视觉质量又满足实时播放的前提下,充分利用带宽.     

基于RTP的MPEG-4自适应传输方案

提出了一种利用RTP协议传输MPEG-4 FGS数据流的方法,能够防止网络拥塞,并且最大限度地利用网络带宽来获取理想的视觉效果.     

基于RTP的MPEG-4视频监控系统的设计

简述了MPEG-4标准的特性和RTP/RTCP协议的概念,详细说明了将MPEG-4码流映射到RTP净荷的方法,最后在此基础上提出了一种基于网络的远程视频监控系统的设计方案.该方案首先给出了系统的设计框架,然后分别阐述了发送端和接收端的具体实现流程.实验结果表明,采用RTP/RTCP协议传输MPEG-4码流能有效利用网络带宽,并且图像质量有较大的提高.     

高分辨视频无线传输的RTP分包方法

重点研究了高分辨率视频图像经MPEG-4压缩后,数据流的RTP分包问题。传输中的丢包率和RTP包的长度有关,为了在无线信道中降低丢包率,改善解码的效果,在RFC3016中规定的基于VOP分包的基础上,提出了一种基于宏块的、能够根据网络状态的变化而自动调整RTP包大小的自适应分包方法。最终将该方法应用于无线枪瞄摄像机,在ARM系统上实现了高分辨率视频图像的采集、编码、无线发送等。实验结果表明,该方法能较好地降低大数据量视频信号的无线传输的丢包率。     

基于MPEG-4实时视频传输系统的设计

本文针对当前实时流媒体系统中存在的一些主要问题,在RTP协议的基础上,构建了基于MPEG-4的实时视频流的传输系统,通过RTP/RTCP的反馈拥塞控制来进行QoS控制和实现了自适应传输.实验结果证明本系统能够获得良好视频效果和稳定性,适合于各种网络.     

基于RTP/RTCP主动丢包的立体视频传输研究

针对立体视频数据量大容易在传输过程中导致网络拥塞的问题,提出一种端到端的拥塞控制传输机制。在NS-2平台上,根据RTP/RTCP在反馈间隔内对丢包个数的反馈信息以及各帧重要性不同的特点,采用在发送端主动丢包的方法优先丢弃不重要的数据,保证较重要的数据信息优先传输。实验结果表明,该机制能有效保护重要帧,增加可解码帧数,增强视频平滑度,与不采用保护拥塞控制相比,可解码帧数均能提高25%以上。     

网格环境中多连接传输机制研究

本文研究了在高带宽、高延迟的网络情况复杂的网格环境中,传输大量数据的多连接并行传输机制.提出采用丢包和数据包往返时间共同作为网络拥塞标志的多连接机制,避免因为网络随机原因丢包引发数据传输的退避机制,降低传输效率.仿真实验证明,该方法比仅用丢包作为拥塞标志的传统多连接机制有更高的运行效率.可充分利用带宽,加快传输速度.完全适合网格环境的特点和需求.     

基于MPEG-4的数字远程集中监控系统设计

分析了IP网络中的远程监控传输服务矛盾，讨论了如何实现数字远程集中监控系统视频传输的实时性，在此基础上给出MPEG-4视频编码标准，介绍了一种远程监控系统设计的体系结构模型与关键的实现技术。该系统采用MPEG-4视频编码标准，提高了压缩比，实现了软件实时压缩、系统视频传输和多路回放采用QoS机制和一个简单的RTP多媒体传输协议，系统传输具有带宽自适应和拥塞控制能力，保证了系统最佳客户端的服务质量。     

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。     

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.