基于虚拟组织和移动代理的网格认证机制研究

认证是网格安全的重要组织部分。在网格中,认证的基本场景包括：证书和证书链、身份认证、会话认证。基于虚拟组织和移动代理的网格特色是以虚拟组织为基本管理单元、以移动代理作为网格结点之间重要的交互手段。本论文的主要内容是把网格认证的基本场景内容引入到基于虚拟组织和移劝代理的网格中。基于虚拟组织的网格认证场景主要包括：用户登录虚拟组织、用户获取虚拟组织内部资源、用户获取虚拟组织外部资源。基于移动代理的网格认证场景主要包括：移动代理和移动代理平台之间交互、移动代理之间交互、移动代理迁移。     

动态虚拟组织管理系统设计与实现

网格计算粗粒度的管理方式导致的网格体系僵化带来了诸多不便,成为网格计算在科研领域更深入应用的阻碍。采用虚拟组织的思想,提出了动态虚拟组织管理方案来针对网格计算项目进行细粒度管理。该方案按照虚拟组织的方式管理多个网格计算项目,以虚拟组织成员关系控制用户访问的权限,使得虚拟组织的构成更加灵活。针对Globus网格平台设计了动态虚拟组织管理系统,实际应用表明该系统实现了细粒度的多网格管理,证明了动态虚拟组织管理方案的有效性。     

支持虚拟组织建立的网格资源协作平台研究

针对基于Internet的学习平台在有效利用教学资源方面存在的问题,采用开放网格服务架构OGSA,建立基于虚拟组织的协作平台.在虚拟组织中,应用或用户能够创建临时服务,资源以网格服务的形式提供给用户或应用.基于OGSA的虚拟组织的建立,为资源共享协作提供了切实可行的解决思路和实施方案.     

网格安全互操作及其在滚动轴承生产中的应用

文章通过分析,当前网格平台通常具有网格全局用户身份以及虚拟组织层次结构的公共特征,基于网格平台的主体类型研究网格平台互操作映射策略,并提出一种通用的滚动轴承安全互操作流程。     

一种基于强信任关系的移动安全认证协议

建立强信任关系来实现对移动代理的安全认证方法,是保护移动代理平台在网格环境中免受恶意代理攻击的主要手段。由于网格的异构性以及虚拟组织之间没有信任传递关系,导致移动代理在跨虚拟组织迁移时,存在安全漏洞,所以结合基于D—S理论的资源信任度函数提出动态规划方案是符合网格结构需求的。该方法在移动代理进行迁移时,由移动代理与其所在的网格虚拟组织中的信任调度模块协同工作,完成移动代理的迁移任务,保护了移动代理不遭到恶意平台的攻击。     

高安全度虚拟组织中动态防火墙的设计和实现

网格计算的本质含义是在动态变化的、拥有多个部门或者团体的复杂虚拟组织内,灵活安全地协同实现资源共享和问题求解[1]。建立安全、稳定、可扩充的虚拟组织是整个网格技术的基础。本文分析了在网格环境下组建高安全度虚拟组织时传统防火墙体制遇到的问题,设计了旨在保障虚拟组织高度安全性的新型动态防火墙模型,并给出了在Linux平台下这种防火墙的实现方法。     

滚动轴承生产中的网格安全相互操作

网格计算为地理分布资源的聚合以及大规模计算问题的解决提供了技术途径,滚动轴承的生产是基于网格平台构建,并通过这些平台管理着滚动轴承的资源/服务,为了聚合不同网格平台管理滚动轴承的资源/服务,需要实现异构网格平台的互操作。由于不同网格平台的安全机制不同,安全互操作是网格互操作中需要解决的一个关键问题。通过分析,当前网格平台通常具有网格全局用户身份以及虚拟组织层次结构的公共特征,基于网格平台的主体类型研究网格平台互操作映射策略,并提出一种通用的滚动轴承安全互操作流程。     

基于网格虚拟组织的分层分布式密钥协议

分析了网格计算系统中面向虚拟组织的动态组密钥管理需求，讨论了基于虚拟组织成员选择环境的“虚拟组织4层结构”和“成员加入策略”，给出了分层分布式密钥协议，避免在密钥的集中式分发与管理模式中，出现单点失败的情况，并具有了层次结构的优点。     

网格资源发现中资源虚拟组织构建方法研究

怎样合理有效地组织网格资源是网格资源发现的关键问题.对网格环境下资源的组织方式进行了研究,提出了网格资源结点动态自组织算法,通过该算法能够将网格资源结点合理有效地组织成具有资源类型的网格资源虚拟组织;提出了资源虚拟组织大小划分的原则,有效地解决了网格资源发现系统中资源虚拟组织与系统规模之间的矛盾,通过仿真试验验证了该方法的有效性.     

一种面向服务网格的通用框架及服务访问模型

网格资源的表示、组织、部署、发现、创建、使用和撤销是网格计算的重要研究问题,随着Webservices技术和服务网格理念的逐步成熟,以“服务”的方式来包装网格资源已经成为了一种趋势,并得到了网格界的一致认同。由于网格资源的“充足性”及“共享性”,采用池的方式来组织网格资源,以及把网格资源包装成服务,是一种很合理的方式。用户对网格的一次访问过程包括访问场景的创建,访问的实施,以及实施完成后的撤销,具有生命期的特征,而这正是虚拟组织所具有的功能,基于虚拟组织来设计服务访问模型是很合理的。基于物理资源池、服务池以及虚拟组织的思想,文章提出了面向服务网格的通用框架模型及服务访问模型VSP,VSP模型被用于指导HowU信息处理平台的设计。     

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。     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

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.     

View-based model-driven architecture for enhancing maintainability of data access services

In modern service-oriented architectures, database access is done by a special type of services, the so-called data access services (DAS). Though, particularly in data-intensive applications, using and developing DAS are very common today, the link between the DAS and their implementation, e.g. a layer of data access objects (DAOs) encapsulating the database queries, still is not sufficiently elaborated, yet. As a result, as the number of DAS grows, finding the desired DAS for reuse and/or associated documentation can become an impossible task. In this paper we focus on bridging this gap between the DAS and their implementation by presenting a view-based, model-driven data access architecture (VMDA) managing models of the DAS, DAOs and database queries in a queryable manner. Our models support tailored views of different stakeholders and are scalable with all types of DAS implementations. In this paper we show that our view-based and model driven architecture approach can enhance software development productivity and maintainability by improving DAS documentation. Moreover, our VMDA opens a wide range of applications such as evaluating DAS usage for DAS performance optimization. Furthermore, we provide tool support and illustrate the applicability of our VMDA in a large-scale case study. Finally, we quantitatively prove that our approach performs with acceptable response times.