知识管理系统中的用户视图

从分析知识管理系统用户的浏览规律出发,以知识管理系统中的元数据为依托,创建了元数据Web页,提出了用户浏览区域和关联集的概念．在分析视图关键要素的基础上,通过对知识管理系统用户获取知识的过程进行分析,构造了用户浏览图和无环图,提出了基于关联集的无环图分解方法,并依据用户兴趣和知识内容构造了判断准则;根据此准则可生成一个充分反映用户意愿的知识管理系统视图．实际应用表明,该方法可以有效地生成与用户兴趣一致的用户视图。     

实视图动态选择算法中重叠实视图的处理

当采用实视图来提高OLAP系统效率时，由于实视图往往并不恰巧是一个完整的格节点，即实视图是多维数据切片（MRFs），因此系统中会出现大量有重叠数据的实视图，这不仅占用了过多的存储空间。也使得系统根据已有实视图响应用户提交的多维查询变得复杂。以往的实视图动态选择算法没有考虑这种情况的处理。文章结合格模型的概念，提出了合并数据重叠实视图的算法，包括如何判定实视图之间有重叠数据、如何合并有数据重叠的实视图等。     

XML递归安全视图的查询重写算法

XML(Extensive Markup Language)安全视图和查询重写是实现访问控制的关键技术.研究了基于XML递归安全视图的查询重写问题,分析了以前有关查询重写的研究工作,提出了一种基于XPath查询语言的能处理递归视图的查询重写算法,并对算法进行了分析,解决了当安全视图中存在递归时把查询进行有效重写的问题,避免了视图的物化和保存.     

关于面向对象数据库系统中用户视图机制的研究

面向对象数据库的模式是按照对象信息的内涵制定的,考虑的因素包括对象的分类、概括、综合、聚集及其所描述的不同类型对象间的联系等。然而不同用户对这些复杂信息的覆盖面有不同的要求,且不一定与系统的数据库模式恰好吻合,这就向面向对象数据库系统(OODBS)提出了支持用户视图、进行数据重构的要求。本文就引入用户视图机理到OODB 中的方法进行了探讨,给出了面向对象用户视图的定义与描述,并讨论了与之相关的数据字典信息,最后提出了建立用户视图所应遵循的原则。     

细述PowerPoint2007的视图方式

PowerPoint是在我们的工作中经常使用的一款软件,想自由的使用该软件,首先要了解它的几种视图方式。PowerPoint提供了四种视图方式,分别为普通视图、幻灯片浏览视图、幻灯片放映视图和备注页视图,在不同的视图方式下,用户可以看到不同的幻灯片效果,本文我们将向大家逐一的详细介绍这四种视图,以帮助大家更好的使用该款软件。     

视图确定性问题及其研究进展

基于视图的查询回答问题在数据管理方面有广泛的应用。为了形式化地描述一组视图V是否含有足够的信息来回答用户提出的一个查询Q;研究人员近期提出了“视图确定性”的概念。介绍了视图确定性相关的研究问题;对比其与查询重写之间的关系;分析出问题的主要研究维度;总结已有的研究成果并指出存在的问题。同时;对未来的研究趋势进行了展望。     

基于物化视图方法优化数据库查询效率

为提高数据库的查询性能,对查询操作进行优化是非常必要的.优化查询速度的措施主要针对数据库管理系统层与应用层,物化视图是其中的一种方法.本文采用物化视图的方法对数据库查询效率进行优化.实验表明,此方法具有较好的优化效果.     

一种基于B/S的通用视图查询模型

提出了一种应用于B/S结构的分布式信息查询系统的通用视图查询模型CVQM ,以增强代码的健壮性、可重用性 ,实现系统的快速开发     

基于物化视图的查询系统研究与实现

在数据库领域,如何加快查询的执行速度非常重要。查询重写技术能透明地利用物化视图回答查询,避免了直接访问大量的原始记录以及耗时的连接和聚集计算,提高了查询 的执行速度。本文讨论了基于数据库中的外键连接关系进行扩展的查询重写方法,以此为核心研究了针对小型数据库的物化视图查询系统,并通过实验证明了物化视图策略的有效性。     

基于用户访问模式的WWW浏览路径优化

分析了WWW用户的浏览活动规律,提出了有关WWW浏览路径优化的一些基本概念,设计了一个基于用户访问模式的浏览路径优化算法,并与相关的工作进行了比较.     

On Leveraging User Access Patterns for Topic Specific Crawling

In recent years, there has been considerable research on constructing crawlers which find resources satisfying specific conditions called predicates. Such a predicate could be a keyword query, a topical query, or some arbitrary contraint on the internal structure of the web page. Several techniques such as focussed crawling and intelligent crawling have recently been proposed for performing the topic specific resource discovery process. All these crawlers are linkage based, since they use the hyperlink behavior in order to perform resource discovery. Recent studies have shown that the topical correlations in hyperlinks are quite noisy and may not always show the consistency necessary for a reliable resource discovery process. In this paper, we will approach the problem of resource discovery from an entirely different perspective; we will mine the significant browsing patterns of world wide web users in order to model the likelihood of web pages belonging to a specified predicate. This user behavior can be mined from the freely available traces of large public domain proxies on the world wide web. For example, proxy caches such as Squid are hierarchical proxies which make their logs publically available. As we shall see in this paper, such traces are a rich source of information which can be mined in order to find the users that are most relevant to the topic of a given crawl. We refer to this technique as collaborative crawling because it mines the collective user experiences in order to find topical resources. Such a strategy turns out to be extremely effective because the topical consistency in world wide web browsing patterns turns out to very high compared to the noisy linkage information. In addition, the user-centered crawling system can be combined with linkage based systems to create an overall system which works more effectively than a system based purely on either user behavior or hyperlinks.     

Web search engine: Characteristics of user behaviors and their implication

In this paper, first studied are the distribution characteristics of user behaviors based on log data from a massive web search engine. Analysis shows that stochastic distribution of user queries accords with the characteristics of power-law function and exhibits strong similarity, and the user' s queries and clicked URLs present dramatic locality, which implies that query cache and 'hot click' cache can be employed to improve system performance. Then three typical cache replacement policies are compared, including LRU, FIFO, and LFU with attenuation. In addition, the distribution character-istics of web information are also analyzed, which demonstrates that the link popularity and replica pop-ularity of a URL have positive influence on its importance. Finally, variance between the link popularity and user popularity, and variance between replica popularity and user popularity are analyzed, which give us some important insight that helps us improve the ranking algorithms in a search engine.     

关于中国Web的大小、形状和结构

基于天网搜索引擎连续4次的大规模搜集记录,揭示了中国2002年初中国Web的大小、形状和结构。主要结论包括：1.中国大约有5000万网页和5万个Web站点;2.全国不到1/3的节市拥有2/3强数目的网站;3,中国网络是高度连通的,Web直径是17.4;4.网页人数分布很好地符合幂级数定律;5.有确凿证据显示,多数的网格社区是自主形成的。     

基于Web的企业协作

随着计算机网络和Internet技术的广泛发展与普遍应用,以World Wide Web为基础来实现企业信息管理与联合协作的商务活动也越来越流行。传统的3层式Wleb应用构架在系统安全性和可扩展性方面已经无法满足Wleb应用开发的需求。根据Internet环境下的数据存储与计算特点,采用软构件技术提出并实现了一个以4层体系结构为基础的基于Wleb的企业信息管理与协作支持平台(WBECP—Wleb Based Enterprise Cooperating Platform)。在给出WBECP系统体系结构模型的基础上,对相关的主要技术进行了分析讨论,并在给出系统具体应用示例的基础上得出最后结论。     

Extracting Logical Schema from the Web

One of the main limitations when accessing the web is the lack of explicit structure, whose presence may help in understanding data semantics. Schema for web data can be constructed at different levels, structuring a single pages or a whole site or group of sites. Here we present an approach to give a logical schema to a web-site, first defining a model for a single page, where its contents is divided into logical sections, i.e. parts of a page each collecting related information. Then, we introduce a site model in which both physical and logical links among different page sections are represented: physical are existing hyperlinks, while logical links are links between sections containing semantically related information. We show how such links can be found and classified according to their relevance, also showing how schema is used in a structure-aware browser to improve both browsing and searching.     

一个基于Web的工作流管理系统

Internet/Intranet/WWW技术的日渐成熟以及资源、应用的日益丰富,为工作流管理系统的构造提供了一个理想的计算环境.在这种易于访问、无处不在的计算环境中,人们可以通过工作流管理系统将各种分布式的信息资源有效地集成、协调起来,以促使企业业务目标的高效实现.文章描述了一个基于Web而构造的通用工作流管理系统Wowww!(workflow on the world wide web),详细讨论了其体系结构的设计、工作流模型及过程实例的执行算法,并讨论了Wowww!为提高其可用性和灵活性而实现的工作     

Amalthaea: An Evolving Multi-Agent Information Filtering and Discovery System for the WWW

Amalthaea is an evolving, multi-agent ecosystem for personalized filtering, discovery, and monitoring of information sites. Amalthaea's primary application domain is the World Wide Web and its main purpose is to assist its users in finding interesting information. Two different categories of agents are introduced in the system: filtering agents that model and monitor the interests of the user and discovery agents that model the information sources.A market-like ecosystem where the agents evolve, compete, and collaborate is presented: agents that are useful to the user or other agents reproduce, while low-performing agents are destroyed. Results from various experiments with different system configurations and varying ratios of user interests versus agents in the system are presented. Finally issues like fine-tuning the initial parameters of the system and establishing and maintaining equilibria in the ecosystem are discussed.     

面向主题的Web信息收集系统的设计与实现

随着互联网信息的持续爆炸性增长，通用搜索引擎的信息覆盖率和检索精度都在不断下降，发展面向主题信息的专用网络信息检索工具已经成为趋势。文中提出的面向主题的Web信息收集系统是这类工具的核心部件，该系统采用文档矢量模型进行文档相关度计算，并结合页面链接的上下文信息过滤页面；借鉴并修改了Shark启发式查找算法来查找相关页面；可采用多机并行下载提高收集效率；并依据站点的重要程度进行动态更新。在一个面向Internet的计算机教学资源检索的搜索引擎中具体实现了这个Web信息收集系统，整个系统在低性能的台式机上就能运行，并可获得较高的属于指定主题的页面的收集精度和收集效率。     

提高SQL Server查询速度的方法

随着应用系统中数据量的增大,提高数据库管理系统SQL Semr的查询和访问数据功能极为必要。本文就提高SQL Server的查询速度问题进行一些分析。