网络日志预处理中优化的会话识别算法

研究网络日志预处理中会话识别问题,会话识别是网络日志数据预处理中最蘑要的一个环节.为使用户准确快速地找到需要的资源,传统网络日志预处理方法采用固定阈值会话识别算法,不能适合网络日志的动态性和不能很好消除网络日志中的冗余信息,导致后继网络日志数据挖掘效率和挖掘精度低.为更好消除网络日志冗余信息,提高后继数据挖掘的效率和精度,提出一种改进的网络日志预处理会话识别算法.新算法可根据页面内容、站点结构确定页面重要程度,对阈值进行动态调整,克服传统固定阈值缺陷,根据用户对页面内容的兴趣度删除不感兴趣页面,消除冗余信息,并对该算法进行了仿真.结果表明,相对于传统网络预测的会话识别算法,新算法能更准确地确定页面访问时间阈值,消除了网络日志冗余信息,提高了网络日志预处理效率和数据挖掘精度.     

基于知识库和改进型免疫算法求解多任务联盟生成问题

联盟生成是MAS的一个关键问题,主要研究如何在MAS中动态生成面向任务的最优Agent联盟.但现有的研究在连续搜索几个类似任务的求解联盟时,都是重新搜索整个求解空间,而没有很好地利用求解的历史信息,从而影响了求解效率.为此,提出了"任务亲和度"的概念,通过建立历史信息的知识库,引入免疫算法来搜索多任务联盟,并对免疫算法进行了改进,提出自适应提取疫苗的策略,在一定程度上加快了解的进化速度.实验结果证明了算法的有效性.     

BP算法在数据挖掘中应用研究

探讨了数据挖掘数据技术的准备工作,由于神经网络方法的特殊性,数据准备更显得尤为重要.对标准的BP算法进行了研究,针对现有人工神经网络中BP算法效率较低、容易陷入局部极小等存在的问题,提出了一种改进的BP算法,并针对这种算法进行了"与"和"异或"问题中的分析测试.测试结果表明了改进的BP算法缩短了学习时间,提高了学习效率,并在一定程度上避免了学习中的局部极小问题.     

基于时间帧的处理器PFair调度改进算法

为了解决PFair算法进行交互任务调度时,由于忽略了不同阶段的周期性任务而导致多个线程之间任务的迁移问题以及空间和时间的浪费问题,提出了基于时间帧的处理器PFair调度改进算法。该算法基于周期性任务系统的特点,引入时间帧控制和改变本地周期性任务调度来限制任务迁移,从而实现对PFair算法的改进。为了评估算法的迁移开销和公平性,通过实验对普通PFair算法及本文所提出的改进算法ERfair进行对比实验,结果表明,改进算法ERfair能够通过时间帧内调度和分区控制大大降低任务在不同处理器间的迁移次数。基于时间帧的处理器PFair调度改进算法在保证公平性的同时,提高了系统的效率,应用于多核处理器上的任务调度是可行的、有效的。     

改进遗传操作PSO算法及其在VRP中的应用

针对车辆路径问题(Vehicle Routing Problem,VRP)是物流系统调度中的关键环节,对车辆路径进行优化调度,可以提高物流经济效益,实现物流科学化.为优化路径,提高搜索效率,针对车辆路径优化问题的特殊性,提出一种改进信息循环利用机制的遗传操作微粒群算法,利用准连续编码算法对解窄间进行编码,引入一种信息保留机制,把所有粒子自身的信息保留为一个信息库,利用信息库对粒子进行重组,实现粒子的更新,从而提高算法搜索的效率.通过仿真表明,在VRP的求解上与遗传算法和双种群遗传算法进行对比研究,证明了微粒群算法是一个求解VRP的较好方案.     

基于数据存储改进的HH算法研究

在路径规划算法中,针对HH算法搜索阶段采用的Dijkstra算法效率较低的问题,采用改进的A*算法进行搜索,基于A*算法中数据存储的方式不同,通过最小二叉堆进行存储排序改进算法,仿真分析得到改进的HH算法在空间效率和时间效率上都得到了提升.     

基于权重树的领域本体片段相似度算法

本体整合和评估时,随着本体库中元素数目的增大,会造成时间和空间的浪费.为了解决该问题,对本体的相似度算法进行了研究,提出了一种基于本体片段映射的算法,通过截取本体中相关片段进行映射.结合电子消费品领域的领域本体实例对算法进行了分析,该算法不仅可以提高大规模本体映射时的效率,同时为进行本体整合和评估提供了一种新的方法.     

信息集成中数据获取关键技术的研究

信息集成是消除信息孤岛,实现信息共享,为企业决策提供支持的核心技术,而数据获取过程是信息集成系统的基础.在数据同步更新研究中,通过根据失配元组的间隔自适应调整窗口大小,在不牺牲效率的前提下有效提高快照差分算法的查全率.进一步,在相似重复记录检测方法的研究中,结合一种新的字符串距离度量算法,并利用二次聚类,提出一种高效的基于条件概率分布的相似重复记录检测方法.最后通过实验对比测试,对快照差分算法以及相似重复记录检测算法的性能和效率进行分析,理论分析和实验结果均证明了提出的改进算法是非常有效的.     

基于粗糙属性向量树的属性约简新方法

在对区分能力大小研究的基础上建立了一个用于指导信息表的绝对属性约简的粗糙集模型, 同时在对区分能力和分类能力二者关系深入研究的基础上提出了决策依赖区分精度新概念,该概念是用于指导决策表的、相对属性约简的一个新的判据.借助粗糙属性向量树提出了新的求全部属性约简的算法, 通过理论分析说明了新算法的最坏时间复杂度低于经典的"基于差别矩阵求全部属性约简算法"以及它的改进算法.对比实验结果验证了该算法在运算效率上明显高于"基于差别矩阵求全部属性约简算法"的改进算法.     

基于约简属性和阈值分割的决策树构建方法

针对决策树C4.5算法在处理连续值属性过程中时间复杂度较高的问题,提出一种新的决策树构建方法：采用概率论中属性间的相关系数（Pearson）,对数据集中的属性进行约简;结合属性的信息增益率,保留决策属性的最优子集,保证属性子集中没有冗余属性;采用边界点的判定,改进了连续值属性离散化过程中阈值分割方法,对信息增益率的计算进行修正。采用UCI数据库中的数据集,在Pycharm平台上进行一系列对比实验,结果表明：采用改进后C4.5决策树算法,决策树生成效率提高了约50%,准确率提升约2%,比较有效地解决了原C4.5算法属性选择偏连续值属性的问题。     

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.     

Call for Papers The 6^th International Conference on Grid and Cooperative Computing

Recent years have seen rapid advances in various grid-related technologies, middleware, and applications. The GCC conference has become one of the largest scientific events worldwide in grid and cooperative computing. The 6th international conference on grid and cooperative computing (GCC2007) Sponsored by China Computer Federation (CCF),Institute of Computing Technology, Chinese Academy of Sciences (ICT) and Xinjiang University ,and in Cooperation with IEEE Computer Soceity ,is to be held from August 16 to 18, 2007 in Urumchi, Xinjiang, China.     

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.     

A pragmatic multi-method investigation of discrepant technological events: Coping,attributions, and ‘accidental’ learning

Discrepant technological events or situations that entail a problem, a misunderstanding or a difficulty with the Information Technology (IT) being employed, are common in the workplace, and can lead to frustration and avoidance behaviors. Little is known, however, about how individuals cope with these events. This paper examines these events by using a multi-method pragmatic approach informed by coping theory. The results of two studies – a critical incident study and an experiment – serve to build and test, respectively, a theoretical model that posits that individuals use a variety of strategies when dealing with these events: they experience negative emotions, make external attributions, and adopt engagement coping strategies directed at solving the event, eventually switching to a disengagement coping strategy when they feel they have no control over the situation. Furthermore, users’ efforts may result in ‘accidental’ learning as they try to overcome the discrepant IT events through engagement coping. The paper ends with a discussion of the results in light of existing literature, future opportunities for research, and implications for practice.     

The Distributed Time-Triggered Simulation Scheme: Core Principles and Supporting Execution Engine

Distributed real-time simulation is a young technology field but its practice is under increasing demands. In recent years the author and his collaborators have been establishing a new approach called the distributed time-triggered simulation (DTS) scheme which is conceptually simple and easy to use but widely applicable. The concept was initiated in the course of developing a new-generation object-oriented real-time programming scheme called the time-triggered message-triggered object (TMO) programming scheme. Some fundamental issues inherent in distributed real-time simulation that were learned during recent experimental studies are discussed along with some approaches for resolving the issues. An execution engine developed to support both the TMOs engaged in control computation and the TMOs engaged in DTS is also discussed along with its possible extensions that will enable significantly larger-scale DTSs.     

Software-Konfigurationsmanagement in großen Softwareprojekten

Zusammenfassung Mit zunehmender Größe der Softwaresysteme verschärfen sich die für die Software-Herstellung typischen Probleme: Beherrschen großer Objektmengen, Erhalten der Systemkonsistenz, Kontrolle der ständigen Änderungseinflüsse und Gewährleisten einer langen Lebensdauer. Die Disziplin Konfigurationsmanagement bildet den methodischen Ansatz, diese Probleme besser zu beherrschen. Software-Konfigurationsmanagement faßt die Herstellung von Softwaresystemen als eine Abfolge von kontrollierten Änderungen an gesicherten Zwischen- und Endergebnissen auf. Dargestellt werden die Objekte und Funktionen des Software-Konfigurationsmanagements sowie die hierfür in großen Software-Projekten benötigten Methoden, Instanzen und Hilfsmittel.     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and     

Editorial:Brain-machine interface(BMI) and cyborg intelligence

正Brain-machine interfaces(BMIs)aim at building a direct communication pathway between the brain and an external device,and represent an area of research where significant progress has been made during the past decade.Based on BMIs,mind information can be read out by neural signals to control     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate     

SCIENCE CHINA Information Sciences SUBJECT INDEX TO VOLUME 57(2014)

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