TMS320C54X实现ITU G.728语音编码标准

ＩＴＵ Ｇ．７２８标准晃国际电信联盟于１９９２年的一种比４特率为１６Ｋｂ／ｓ低延时ＣＥＬＰ类型语音编解码器。本文首先对Ｇ．７２８编解码算法和定点数字处理芯片ＴＭＳ３２０Ｃ５４Ｘ作了简单介绍。由于Ｇ．７２８标准是一种低延时语音编码标准,因此计算复杂度高,在实时实现中需要作特别处理。本文着重介绍了这种低延时ＣＥＬＰ（ＬＤ－ＣＥＬＰ）算法在ＴＭＳ３２０Ｃ５４Ｘ上实现的软、硬件设计和在定点ＤＳＰ芯片实现此     

数字语音编解码的一种DSP实现方法

本文针对ＩＴＵ Ｇ．７２８标准语音编解码器,提出了一种ＤＳＰ的实现方法。在简介Ｇ．７２８编解码和ＤＳＰ芯片ＴＭＳ３２０Ｃ５４１基础上,本文主要研究了ＣＥＬＰ（ＬＤ－ＣＥＬＰ）算法在ＴＭＳ３２０Ｃ５４１上的实现和实现此算法的一些关键技术,并给出了实际仿真结果。     

用TMS320C6201实现多路ITU-T G.728语音编码标准

ＩＴＵ－Ｔ Ｇ．７２８标准是国际电信联盟于１９９２年制定的比特率为１６ｋｂｉｔ／ｓ的低延时ＣＥＬＰ类语音编码器。在扼要介绍Ｇ．７２８编解码算法原理和ＴＭＳ３２０Ｃ６２０１定点ＤＳＰ芯片的基础上,详细讨论了Ｇ．７２８算法在ＴＭＳ３２０Ｃ６２０１上实时实现的硬件设计和软件开发及优化的关键技术。实验结果表明,单片Ｃ６２０１能实现至少４路Ｇ．７２８语音编解码。     

GATR－C50开发应用系统研制

介绍了一种以ＴＭ３２０Ｃ５０为数字信号处理器，以ＩＢＭ－ＰＣ（ＸＴ，ＡＴ，３８６，４８６及兼容机）为主机的微机扩展系统。该系统可直接插在ＰＣ机的扩展槽中，充分利用ＰＣ机的软硬件资源，实现ＤＳＰ应用程序的开发、信号的实时显示和记录等。系统板上还带有ＴＬＣ３２０４４专用芯片，可直接用于语音信号的采集与处理。     

用TMS320C25与PC机构成的并行计算机系统

ＴＭＳ３２０Ｃ２５是一种高性能数字信号处理器。本文介绍了一种用ＴＭＳ３２０Ｃ２５与ＰＣ机构成的主从结构并行计算机系统。该系统的特点是将ＴＭＳ３２０Ｃ２５高速数字信号处理系统作为ＰＣ机的插件板，直接插入ＰＣ机的扩展槽中，利用双口ＲＡＭ实现ＴＭＳ３２０Ｃ２５与ＰＣ机之间的相互通讯。它能适用于高速数字信号处理、图形／图像处理、语音处理等。文中详细论述了系统的工作原理、硬年龄件结构，包括总体设计、接口设计     

语音合成系统中的容量储存问题

分析了基于ＬＰＣ技术的语音压缩编码，介绍了美国德州仪器公司采用ＬＰＣ技术设计的ＴＳＰ５０Ｃ１Ｘ语音合成芯片。研究了智能语音系统中的容量储存问题，设计了基于ＴＳＰ５０Ｃ１０芯片的语音合成系统及扩容方法，给出了硬件设计图。     

多媒体通信中的双速率语音编码技术分析研究

ＩＴＵ－Ｔ Ｇ．７２３．１是国际电信联盟制定的适用于多媒体通信的双速率语音编码标准。本文主要介绍了该标准的算法原理,并讨论了两种速率下的激励矢量搜索技术。该标准及其附录Ａ的功能可在ＴＭＳ３２０Ｃ５４０２上实现。     

高效率多通道语音记录系统的研制

介绍一种采用一片ＴＭＳ３２０Ｃ５４２ ＤＳＰ实现４路电话压缩的话音处理卡,对处理卡硬件结构和ＲＰＥ－ＬＴｈ算法及ＤＳＰ实现作了叙述,最后提出一种基于该处理卡的语音记录系统的构想。     

PC386／486与DSP TMS320C30大容量双寻址RAM接口设计方法

文中详细介绍了一种ＰＣ３８６／４８６与高速数字信号处理芯片ＴＭＳ３２０Ｃ３０与大容量双寻址ＲＡＭ接口设计方法。采用滑动窗的存储器映象技术实现对２Ｍ×１６位双寻址ＲＡＭ的访问。采用ＴＭＳ３２０Ｃ３０的分组开关技术实现对各组存储器之间的隔离。双寻址ＲＡＭ可由ＰＣ主控，ＴＭＳ３２０Ｃ３０兼控     

TMS320C25与IBM—PC机的串行通讯

本文介绍了高数字信号处理（ＤＳＰ）芯片ＴＭ３２０Ｃ２５与ＩＢＭ－ＰＣ机进行串行通讯的实现方法，文中对ＴＭＳ３２０Ｃ２５的串行通讯接口电路和通讯程序作了论述。     

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).