基于框架技术的通用虚拟计算平台的实现

通过分析目前几种虚拟计算环境的现状、特点及适用范围,针对聚合异构分散计算资源的需求,提出了一种基于框架技术的虚拟计算环境的实现方法.研究了虚拟计算环境的关键实现技术,主要包括计算平台的总体框架和服务组件,以及各个组成部分之间的关系和通信方式;并基于服务分层设计方法来优化计算服务的架构,对各服务组件进行了详细的设计,实现了虚拟计算平台系统.以地震资料数据处理为例进行了实验测试,测试结果表明,该虚拟计算框架具有一定的可行性和有效性,能够整合零散、异构的计算资源,尤其适用于性能差异明显的计算组织,为用户提供了透明的资源访问模式,提高了计算资源的利用率.     

虚拟计算环境中的多机群协同调度算法

基于虚拟计算环境的核心机理,提出由自主调度单元、域调度共同体、元调度执行体为核心的多机群协同系统框架.剖析多机群任务并发运行性能模型,设计了多机群协同调度算法框架,提出最大空闲节点优先、最小网络拥塞优先、最小异构因子优先与最小异构空闲节点优先4种启发式资源选择策略.实验验证了协同调度模型与算法在任务集完成时间与系统平均利用率的测度上的有效性.     

基于框架技术的通用虚拟计算平台实现方法

通过分析已有虚拟计算环境的现状、特点及适用范围,针对聚合异构分散计算资源的需求,提出一种基于框架技术的虚拟计算环境实现方法,包括计算平台的总体框架和服务组件,以及各个组成部分之间的关系与通信方式的实现。采用服务分层设计方法优化计算服务的架构,完成对各服务组件的设计。以地震资料数据处理为例对虚拟计算平台进行实验测试,结果证明,该方法具有可行性,能够整合零散、异构的计算资源,尤其适用于性能差异明显的计算组织。     

基于蚁群算法的Hadoop资源感知调度器研究

通过研究蚁群算法,针对现有Hadoop调度器的不足,提出一个基于蚁群算法的Hadoop资源感知调度器及其具体实现方案。从而使Hadoop作业调度器可以更有效地对任务进行分配,提高整体架构的作业性能。通过实验证明,利用蚁群算法实现的资源感知调度器在同构环境中虽没有明显改善系统计算速度,但是在异构环境中可以很好提高系统处理任务的性能,降低了运算时间。     

基于多维QoS和云计算的资源负载均衡调度研究

为了实现云环境下虚拟资源的高效调度并满足用户QoS需求,提出了一种基于多维QoS能实现负载平衡的云资源调度方法;首先,建立了云资源调度的多维QoS数学模型,然后提出了一种基于蚁群算法实现云环境虚拟资源调度的算法,对信息素的初始化、虚拟机的选择以及信息素的更新等均进行了改进,并在算法中引入遗传变异因子以提高算法的收敛能力;实验结果表明:该算法能有效解决云环境下虚拟资源调度问题,减少负载均衡离差,较其它方法具有较大优越性,满足了云环境下资源调度的需求。     

iVCE中基于可信评价的资源调度研究

随着网格计算、P2P、Web服务技术在电子商务、电子政务领域应用的不断扩展,基于Internet的资源共享的安全可信问题变得越来越重要.该文在基于Internet的虚拟计算环境(Interenet-Based Virtual Computing Environment,iVCE)的资源共享的用户与资源关于身份可信、能力可信、行为可信的信任模型的基础上,提出了一种可信优化的资源调度算法.算法基本思想在于根据用户对资源可信的需求,对虚拟计算环境中的自主元素可信度综合考察与评价,以用户可信满意度为优化调度目标调度资源,进而基于min-min算法优化任务执行时间,满足了资源调度的可信保障,同时具有较好的性能.仿真实验结果表明可信优化调度算法能够在iVCE的信任度效益,最早完工时间,失效服务请求数,资源利用率等性能参数方面明显优于min-min和max-min算法.     

网格资源超图划分聚类任务调度

网格计算是当前一个活跃的研究领域,其中任务调度是实现网格计算目标的一个重要部分.为获得良好的网格任务调度性能,提出了一种基于资源超图划分聚类的网格任务调度算法RHPC.该算法根据网格环境下资源数量庞大、异构、多样的特点,在构建的网格资源超图模型基础上,预先对资源进行性能划分聚类,将任务与聚类资源相匹配并实施调度.模拟实验结果证明算法缩短了任务资源相匹配的时间,提高了任务调度的性能,是一种有效的网格任务调度算法.     

分布式本体集成框架下虚拟本体集合动态生成算法

为了有效组织和管理网格环境内存在的各类分布异构的本体资源,提出了基于网关服务的分布式本体集成框架.从体系结构角度对本体集成过程中涉及到的功能模块进行分析和划分,并基于网格服务设计了关键组件.在此基础上从提高计算资源利用率和满足用户多样性需求的角度出发,提出了虚拟本体集合动态生成算法.该算法将缓存技术与虚拟本体相结合,为本体数据的自动生成和再生成提供了较完整的系统方法,增强了本体资源的复用性.实验结果表明,该算法可以提高计算资源利用率,实现本体资源的复用率.     

基于主机性能度量的异构集群作业调度算法

传统经典作业度算法在集群应用中实现简单、执行效率高,但在异构集群环境下由于缺乏在线节点运行状态动态反馈能力和负载均衡能力,降低了计算资源利用率和系统吞吐率.为解决上述问题,设计了一种在异构集群环境下基于主机性能度量的作业负载均衡调度算法,该算法通过收集集群中在线节点的状态信息和作业响应时间遴选出可信节点集合,计算出各可信节点的HPM值,利用负载均衡运算规则生成候选的作业分配节点集合,最终按照预先设计的优先原则把不同作业分配至各计算节点,并更新各节点运行状态.实验结果表明,在异构集群环境下调度同类型作业时,该算法在总完成时间和负载均衡性能等指标上均优于传统经典算法.     

一种用于异构环境中并行任务调度的弹性节能算法

节能调度算法设计是高性能计算领域中的一个研究热点。本文通过软件方法设计异构多核计算机的调度算法,实现系统的弹性节能,达到降低能耗并提升系统性能的目的。本文的调度策略建立在基于处理器异构的并行任务调度的环境中,构建了节能模型,提出了EAPS（Energy-aware parallel scheduling）算法模型,该算法在每一任务完成之后重新计算优先级以使优先级符合任务的实时情况,并对复制的前驱任务是否冗余任务进行判断从而避免资源的浪费,并通过调节节点电压选择能耗最少的节点进行调度,在节能与期望完成时间之间取得平衡。     

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.