基于ADSP—Blackfin533的H．264视频编码器的实现

描述了基于ADSP—Blackfin533平台的H．264高性能视频编码器的设计和实时实现。首先介绍了编码器硬件结构设奠？嚣而茹述了编码算法的移植以及基于Blackfin533结构和专用视频操作指令的算法优化，重点讨论了H．264算法帧间预测算法的改进。     

基于DM642的H.264视频编码器优化与实现

H.264是新一代的视频压缩标准.本文首先研究了该标准的主要内容,然后简要介绍了DSP TMS320DM642的出色性能及其视频驱动程序的实现,最后讨论了H.264编码在DSP TMS320DM642上的优化与实现.     

DSP翻新16位

6月12日,ADI 公司在北京发布了Blackfin 系列16位数字信号处理器(DSP)。这是 ADI 公司与英特尔联合开发的体现高性能体系结构的首款 DSP。这种为通信和一系列因特网应用而设计的新的 Blackfin DSP,通过易编程的     

基于DSP实时实现的H.264运动估计快速算法

综合考虑运动估计的精度和搜索次数．提出了一种在DSP上实现符合H．264标准的运动搜索快速算法．该算法结合了钻石搜索和分层搜索的思想，在抽样块上进行菱形搜索，同时自适应预测搜索起始点，在保证估计质量的情况下减少了冗余搜索次数,极大的提高了搜索效率，对在DSP上实现H．264实时编码器具有重要的实用价值．     

基于Blackfin的嵌入式系统移植

Blackfin系列数字信号处理器（DSP）是ADI公司最新的基于微信号体系结构的DSP,具有快速数据处理能力和很高的性价比,在多媒体和通信等领域得到广泛应用。介绍了一种基于Blackfin的嵌入式Nucleus系统移植技术,包括开发环境的建立、系统引导程序的设计实现以及Nucleus系统的初始化等,为基于DSP嵌入式系统的开发提供了很好的借鉴。     

基于VxWorks和DM642视频采集压缩系统的技术研究

介绍了一种基于VxWorks和DM642下应用目前最新的H.264视频编码算法实现视频采集压缩系统的方法,主要内容包括视频采集压缩系统的硬件实现平台、VxWorks下PCI驱动、H.264视频编码算法标准、DSP软件编程及H.264视频编码算法的实现等,最后给出了H.264视频编码器的性能测试。     

基于VxWorks和DM642下视频采集压缩系统的技术研究

介绍了一种基于VxWorks和DM642下应用目前最新的H.264视频编码算法实现视频采集压缩系统的方法,主要内容包括视频采集压缩系统的硬件实现平台、VxWorks下PCI驱动、H.264视频编码算法标准、DSP软件编程及H.264视频编码算法的实现等,最后给出了H.264视频编码器的性能测试。     

面向医用电子内窥镜的高清视频处理系统

设计一种基于现场可编程门阵列(FPGA)和双数字信息处理器(DSP)的嵌入式高清内窥镜视频处理系统。利用FPGA对视频数据进行预处理,采用2片基于DaVinci-HD技术的DSP进行H.264编解码并行运算,通过PowerPC处理器完成系统管理、视频存储与网络传输。测试结果表明,该系统实时处理的视频分辨率达到1080i60,在图像质量上能达到H.264的高画质级别。     

基于Blackfin533 DSP的MPEG-4视频编码器设计

阐述的对象是基于Blackfin533 DSP的MPEG-4视频编码器。结合Blackfin533 DSP的结构特点和MPEG-4视频压缩标准的蛮时性要求，详细介绍了系统硬件设计、接口驱动程序设计、编码程序设计，提出实现方案。     

基于TMS320DM642芯片H.264编码器的设计

作为新一代视频压缩协议H．264,理论上已经证明它能比其它视频压缩协议表现出更好的性能,更能适应无线多媒体网络多媒体的应用需求。但是由于H．264协议自身的复杂性以及控制的灵活性,使得如何设计H．264编码器成为工程设计人员必须考虑的问题。采用具有较高运算速度的TMS320DM642DSP芯片作为H．264编码器实现的硬件平台,结合合适的编码器控制算法,将有效地解决这个问题,实现满足应用需求的H.264编码器。     

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。     

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.     

Editorial: Special issue on recent advances in hybrid control theory and applications

正The demands of a rapidly advancing technology for faster and more accurate controllers have always had a strong influence on the progress of automatic control theory.In recent years control problems have been arising with increasing frequency in widely different areas,which cannot be addressed using conventional control techniques.The principal reason for this is the fact that a highly competitive economy is forcing systems to operate in regimes where     

Information for Authors

正Aim The Journals of Zhejiang University-SCIENCE(A/B/C)areedited by the international board of distinguished Chinese andforeign scientists,and are aimed to present the latest devel-opments and achievements in scientific research in China andoverseas to the world’s scientific circles,especially to stimulateand promote academic exchange between Chinese and for-eign scientists everywhere.     

Enhancing a leaf radiative transfer model to estimate concentrations and in vivo specific absorption coefficients of total carotenoids and chlorophylls a and b from single-needle reflectance and transmittance

The relative concentrations of different pigments within a leaf have significant physiological and spectral consequences. Photosynthesis, light use efficiency, mass and energy exchange, and stress response are dependent on relationships among an ensemble of pigments. This ensemble also determines the visible characteristics of a leaf, which can be measured remotely and used to quantify leaf biochemistry and structure. But current remote sensing approaches are limited in their ability to resolve individual pigments. This paper focuses on the incorporation of three pigments—chlorophyll a, chlorophyll b, and total carotenoids—into the LIBERTY leaf radiative transfer model to better understand relationships between leaf biochemical, biophysical, and spectral properties.Pinus ponderosa and Pinus jeffreyi needles were collected from three sites in the California Sierra Nevada. Hemispheric single-leaf visible reflectance and transmittance and concentrations of chlorophylls a and b and total carotenoids of fresh needles were measured. These data were input to the enhanced LIBERTY model to estimate optical and biochemical properties of pine needles. The enhanced model successfully estimated reflectance (RMSE = 0.0255, BIAS = 0.00477, RMS%E = 16.7%), had variable success estimating transmittance (RMSE = 0.0442, BIAS = 0.0294, RMS%E = 181%), and generated very good estimates of carotenoid concentrations (RMSE = 2.48 µg/cm², BIAS = 0.143 µg/cm², RMS%E = 20.4%), good estimates of chlorophyll a concentrations (RMSE = 10.7 µg/cm², BIAS = − 0.992 µg/cm², RMS%E = 21.1%), and fair estimates of chlorophyll b concentrations (RMSE = 7.49 µg/cm², BIAS = − 2.12 µg/cm², RMS%E = 43.7%). Overall root mean squared errors of reflectance, transmittance, and pigment concentration estimates were lower for the three-pigment model than for the single-pigment model. The algorithm to estimate three in vivo specific absorption coefficients is robust, although estimated values are distorted by inconsistencies in model biophysics. The capacity to invert the model from single-leaf reflectance and transmittance was added to the model so it could be coupled with vegetation canopy models to estimate canopy biochemistry from remotely sensed data.     

Mr. Twinn’s bombes

This article discusses the history and design of the special versions of the bombe key-finding machines used by Britain’s Government Code & Cypher School (GC&CS) during World War II to attack the Enigma traffic of the Abwehr (the German military intelligence service). These special bombes were based on the design of their more numerous counterparts used against the traffic of the German armed services, but differed from them in important ways that highlight the adaptability of the British bombe design, and the power and flexibility of the diagonal board. Also discussed are the changes in the Abwehr indicating system that drove the development of these machines, the ingenious ways in which they were used, and some related developments involving the bombes used by the U.S. Navy’s cryptanalytic unit (OP-20-G).