基于网格的电大网络教育资源整合模式

建设优质的电大网络教育资源及其服务是电大远程教育长远发展的一大重要课题,通过对电大网络教育资源及其服务现状的调查,文章提出利用网格技术实现电大网络教育资源的整合优化模式,分别从网格系统框架、基本原则、组织形式、整合模式等方面阐述电大网格系统的建设,各电大网格节点统一规划、分工协作,在网络教育理论指导下或进行资源开发,或着重开发网格服务,实现电大网络教育资源的全面共享。     

基于Globus Toolkit4的网格多资源Web服务实现

采用Globus作为事实上的网格基础平台,基于Globus进行网格服务开发是当前开发网格应用系统的主要手段.它提供了网格系统的基础服务,可以构建复杂的网格应用系统.针对GlobusToolkit4中网格服务的实现问题,介绍了单资源服务、多资源服务的实现模型,并以一个简单的网格计算为例,详细地说明了网格多资源Web服务的实现过程,最后成功地在单资源网格服务的基础上实现了网格多资源服务.     

一种基于GMA结构的开放式网格资源信息服务

网格是把广域网上大量分布、异构资源进行整合，实现统一视图和统一访问接口的基础设施．资源信息服务在网格中具有重要地位，其作用是感知和监控异构资源，并为上层应用提供资源信息，从而为资源调度和选择系统策略提供依据．传统的主机监控不能适用于网格，现有的网格资源信息服务也存在一定缺点．通过分析网格资源信息服务的一般要求，针对现有系统的不足，基于GGF提出的GMA体系结构，从几个不同方面提出了更适合网格特点，开放性和互操作性较好的改进方案，最后，一方面对资源信息服务的性能策略进行了讨论和理论分析，另一方面以目前实现的原型系统GridEye为基础，进行了资源信息服务的性能测试实验，并对结果进行了分析．     

基于EJB技术的网络教育资源管理系统

本文首先介绍了网络教育的发展趋势和开发网络教育资源管理软件的必要性，然后介绍了基于EJB技术的网络教育资源管理系统的总体结构、模块构成、系统实现以及关键技术。该系统在实际运行中能很好的对网络教育资源进行管理．提高网络教育资源利用率。     

科学规划,强化应用,构建教育教学网络资源库

近几年来,我们坚持建设硬件、强化培训、开发资源、服务教育的教育信息化工作方针,通过自主开发、引进和整合等途径,建立共建共享的激励机制,形成了具有温州特色的网络教育资源建设     

科学规划,强化应用,构建教育教学网络资源库

近几年来,我们坚持"建设硬件、强化培训、开发资源、服务教育"的教育信息化工作方针,通过自主开发、引进和整合等途径,建立共建共享的激励机制,形成了具有温州特色的网络教育资源建设     

浅谈网格及其在校园网中的应用

该文对网格研究的基本问题网格服务开发平台和环境进行了探讨,以期有助于网格的创新研究和应用开发。结合GT3介绍了基于网格技术的校园网资源建设和服务的一般模式。     

LDAP目录服务的实现及在网络教育系统中的应用

网络教育系统是由若干分布式异构子系统构成,需要对这些子系统进行信息整合,形成完整的网络教育业务流程。在集成方案中,采用了LDAP目录服务来实现网络教育中资源的组织与定位以及各子系统公告信息的发布功能。目录技术的使用大大降低了系统集成的复杂性和应用系统测试、部署的时间,同时提高了网络教育系统整体的可扩展性。     

网格技术在智能公交系统中的应用

阐述了将网格技术应用于实现智能公交系统的基本思想和部分技术的实现方法。网格技术通过对异构资源的整合,能够实现更高程度的资源共享和更强的计算能力,它为实现智能公交系统提供了一种有效的解决方案。在本文中,首先提出了基于"服务"的系统分层体系结构,包括资源服务层、基础服务层与系统服务层,然后阐述了基于OGSA的关于智能公交系统的信息集成、功能封装和应用开发的设计思想和方法,并且采用请求/应答与订阅/知两种方式实现了信息集成。     

反垃圾邮件网格系统的设计与实现

设计和实现了一种基于OGSA的反垃圾邮件网格系统，该系统解决了目前主流反垃圾邮件技术中存在的过于依赖服务器的缺点，通过网格对计算资源的强大整合和利用能力，为大量的反垃圾邮件计算服务。     

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).