基于MSTP的城域传送网组网与应用

随着数据业务的迅速发展,城域网业务主体正在发生深刻变化,业务类型从单纯的TDM业务为主、2Mb／s为颗粒向数据业务为主、宽带接口过渡,基于SDH的MSTP、弹性分组环（RPR）、波分复用技术等各种城域多业务传送（MSTP）技术应运而生。与骨干网相比,城域传送网具有业务种类多、业务调度转接多、业务流量变化大的特点,并且在市场需求的不断推动下,各种技术在实际应用中呈现融合发展的趋势。文章在简要介绍城域多业务传送技术的基础上,讨论了基于MSTP的RPR城域传送网的组网和应用,并给出了组网案例。     

多厂商MSTP设备互联互通的关键技术

基于SDH的多业务传送节点(MSTP)是指基于SDH平台而实现TDM业务、ATM业务、以太网业务的接入、处理和传送,并提供统一网管的多业务节点。MSTP已经成为建设以城域网为代表的多业务传送网的首选技术,它具有将分组数据业务高效地映射到SDH虚容器的能力,并且可以采用SDH物理层保护使承载的数据业务具有高可靠性。MSTP良好的多业务拓展能力以及业务QoS保证得到了运营商的认可。众所周知,不同厂商设备的互通性既是规划电信网络的关键因素,也是决定一项新技术能否大规模应用的关键因素。由于城域网的各传送子网通常由不同厂商的MSTP…     

城域网MSTP组网方案与应用

立项背景随着MSTP在城域网中的广泛应用,城域传送网正在实现从基础承载网络向业务网络的转变。如何整合城域传送网和数据网,在城域网中有效地提供新业务是运营商面临的挑战。本项目的目标是以业务为导向,综合考虑城域传送网和IP城域网,提出新的城域传送网组网方案和业务发展策略。发现或创新点“城域传送网新技术研究与业务发展策略”总结分析了传送网承载以太网体系结构(EOT)的具体内容和关键技术,在此基础上对MSTP关键功能组网的关系进行了重点研究。分析比较了不同的以太网业务定义,提出了基于MSTP的以太网业务框架和发展策略。项…     

浅谈城域网光传输技术

近年来,无论是光传输技术还是光传输网络的部署和应用都有了新的发展。而光城域传输网的建设也正面临新的挑战。城域传送网不是一个新的概念,特别是对于已经拥有庞大城市传输网的运营商(例如中国电信)以及众多企业网络(例如政府、电力、金融)而言。我们谈论的城域网建设,不是重新敷设一张新的传输网(专门承载数据业务),而是在城域地区对以前建设的传输网进行优化和改造。目前城域网由上至下可纵向划分为三种网络:业务网、传送网、光缆网。城域网技术的发展有三个主流方向,即IP城域网技术、城域以太网技术、光城域网技术。其中IP城域网技术…     

宽带城域网设计原则及组网技术分析

本文介绍了典型的宽带城域网组网技术,包括千兆以太网（GE）技术、POS（Packet over SDH）技术、以SDH为基础的多业务传送平台（MSTP）技术、ATM技术以及弹性分组环（RPR）技术,对它们的特点、优缺点和适用范围进行逐一分析,并给出了宽带城域网的设计原则。     

城域传送网演进策略探讨

随着数据业务的高速增长,基于SDH技术的城域传送网逐渐成为了全网的带宽瓶颈。本文对城域传送网的现状和特点进行了分析,介绍了几种主要的组网技术,提出了城域传送网一种新的演进策略。     

MSTP技术的应用与研究

随着电信业务的急剧变化和发展,电信传统的TDM传输业务已经不能满足市场的需求,一种新的城域网技术基于SDH的综合多业务传送平台MSTP应运而生,本文主要讨论MSTP的特点,并且研究在电信将来的网络建设中如何充分利用MSTP的这些特性和优势.     

MSTP技术发展与应用

MSTP多业务传送平台基于SDH技术，同时实现TDM、ATM、以太网等业务的接入、处理和传送，并提供统一的网管，它具有SDH,ATM以及以太网／IP处理功能，通过将多业务汇聚并高效适配的方式可以实现多种业务的综合传送。论文首先回顾了MSTP发展、接着报告了MSTP相关的主要技术，从中可以大致了解MSTP的原理和其今后相关技术发展的趋势。     

基于SDH的MSTP技术发展及应用探讨

本文对基于SDH的多业务传送平台MSTP技术几个阶段的发展进行分析和比较,介绍MSTP的关键技术——多协议交换标记(MPLS)和ATM反向复用(IMA),对MSTP的主要应用方向进行探讨,对MSTP的不同层次在城域网中的部署策略进行分析。     

MSTP技术新发展和3G传输

随着数据业务的迅猛发展，城域网承载主体正在发生深刻变化，城域多业务传送平台(MSTP)的出现延长了SDH的寿命。是“光发展低潮”中的亮点。文章结合新一代MSTP的关键技术，讨论了MSTP未来的发展方向。另外，3G技术是无线通信乃至整个通信界的重要发展方向，传输专业也要与时俱进地适应这种变化，文章根据WCDMA系统对传输的需求．提出了相关的解决方案。     

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).