基于移动代理的分布式信息检索

介绍了移动代理技术的内容和特点，分析了其性能优势。在此基础上，重点论述了基于移动代理技术的分布式信息检索的系统模型、系统实例、性能指标和移动代理规划。指出移动代理技术在分布式信息检索中的应用，是解决网络环境下分布式大量信息资源检索的有效途径。     

分布式情报检索系统的拓扑模型

本文建立了分布式情报检索系统的三种拓扑模型———检索拓扑 ,伪度量拓扑和相似性拓扑 ,并证明了检索拓扑与相似性拓扑具有一定的分布式特征 ,从而说明了这两种拓扑模型在分布式意义下的合理性。     

Retrieving Information from a Distributed Heterogeneous Document Collection

This paper describes a probabilistic model for optimum information retrieval in a distributed heterogeneous environment.The model assumes the collection of documents offered by the environment to be partitioned into subcollections. Documents as well as subcollections have to be indexed, where indexing methods using different indexing vocabularies can be employed. A query provided by a user is answered in terms of a ranked list of documents. The model determines a procedure for ranking the documents that stems from the Probability Ranking Principle: For each subcollection, the subcollection's documents are ranked; the resulting ranked lists are combined into a final ranked list of documents, where the ordering is determined by the documents' probabilities of being relevant with respect to the user's query. Various probabilistic ranking methods may be involved in the distributed ranking process. A criterion for effectively limiting the ranking process to a subset of subcollections extends the model.The property that different ranking methods and indexing vocabularies can be used is important when the subcollections are heterogeneous with respect to their content.The model's applicability is experimentally confirmed. When exploiting the degrees of freedom provided by the model, experiments showed evidence that the model even outperforms comparable models for the non-distributed case with respect to retrieval effectiveness.     

利用移动Agent技术改进基于概念的信息检索

在简单介绍有关移动Agent的技术以后,详细介绍基于概念的信息检索模型的框架和部 分实现,并提出利用移动Agent的相关技术对基于概念的信息检索进行改进的若干思路。     

基于Z39．50的分布式联机书目检索

Z9．50是网络信息检索的标准协议,目前主要应用于联机书目检索领域。本文首先探讨基于Z39．50的联机书目检索的技术以及目前面临的问题,然后提出一个应用查询路由技术的分布式结构,并讨论了MARC索引的组织,节点质心信息的提取,查询循环控制等关键技术。文中提出的系统结构和实现技术有助于提高数字图书馆环境中分布资源的查询效率。     

问答式信息检索查询优化技术研究

问答式信息检索是新一代搜索引擎,它接收自然语言描述的问题,在文档集合中搜索并返回问题的精确答案.问答式信息检索中,检索模块性能的提高将直接影响问题回答系统的整体性能.本文研究系统中的查询优化技术,包括两种策略:基于模式知识库的查询优化;挖掘Web语义蕴含信息,构建查询扩展资源.本文利用TREC提供的问题集与答案集(TREC8-TREC13)做实验来测试查询优化方法的性能,实验结果表明,相对于传统的查询生成,本文采用的查询优化技术在检索精度上取得了提高,t-test结果证明,系统性能提高统计显著.     

基于XML的分布式信息检索

提出了一种对互联网信息进行分布式信息检索的方法：利用代理程序和XML技术向多个相同类型的网站同时发送检索请求文档并接收它们返回的检索结果文档，经过统一处理后将检索结果显示给读者     

信息检索系统中的相关反馈技术

本文论述了布尔模型、向量空间模型以及概率模型中所采用的相关反馈技术,其中主要集中于检索词权值调整以及查询扩展等两项技术。作者还讨论了相关反馈技术对检索性能影响的评估方法,并提出了相关反馈在实际应用中需要解决的问题。     

Partial Collection Replication for Information Retrieval

The explosion of content in distributed information retrieval (IR) systems requires new mechanisms in order to attain timely and accurate retrieval of unstructured text. This paper shows how to exploit locality by building, using, and searching partial replicas of text collections in a distributed IR system. In this work, a partial replica includes a subset of the documents from larger collection(s) and the corresponding inference network search mechanism. For each query, the distributed system determines if partial replica is a good match and then searches it, or it searches the original collection. We demonstrate the scenarios where partial replication performs better than systems that use caches which only store previous query and answer pairs. We first use logs from THOMAS and Excite to examine query locality using query similarity versus exact match. We show that searching replicas can improve locality (from 3 to 19%) over the exact match required by caching. Replicas increase locality because they satisfy queries which are distinct but return the same or very similar answers. We then present a novel inference network replica selection function. We vary its parameters and compare it to previous collection selection functions, demonstrating a configuration that directs most of the appropriate queries to replicas in a replica hierarchy. We then explore the performance of partial replication in a distributed IR system. We compare it with caching and partitioning. Our validated simulator shows that the increases in locality due to replication make it preferable to caching alone, and that even a small increase of 4% in locality translates into a performance advantage. We also show a hybrid system with caches and replicas that performs better than each on their own.     

与自然语言查询表述相关的词语分析

考察在信息检索过程中用户以自然语言表述的查询语句中的词语使用情况。以一个信息需求描述颗粒度不等的查询表述语料库为素材,辅以汉语通用语料作为对照,通过词频以及词语的文本覆盖率等统计数据,按照是否需要在目标文本中直接或以其他形式出现,将查询表述语句中的词语区分为对汉语文本处理具有普遍意义的通用停用词、服务于信息检索表述用的专用停用词和与特定需求相关的信息内容词语。区分词语使用的不同性质,能为信息系统前端的自然语言查询处理增加一道剥离工序,防止将整个查询语句的分词结果全部作为检索项所造成的效率和准确率的退化。     

跨语言信息检索理论与应用研究

随着互联网的全球化发展趋势，跨语言信息检索日益成为信息检索领域中的重要课题，跨语言检索可用一种提问语言检索出用另一种语言书写的信息。文章主要对跨语言信息检索理论应用研究进行了探讨，并对其在专业领域数据库中的应用提出一种思路。     

Dipe-D: A Tool for Knowledge-Based Query Formulation in Information Retrieval

The paper reports the development of Dipe-D, a knowledge-based procedure for the formulation of Boolean queries in information retrieval. Dipe-D creates a query in two steps: (1) the user's information need is developed interactively, while identifying the concepts of the information need, and subsequently (2) the collection of concepts identified is automatically transformed into a Boolean query. In the first step, the subject area—as represented in a knowledge base—is explored by the user. He does this by means of specifying the (concepts that meet his) information need in an artificial language and looking through the solution as provided by the computer. The specification language allows one to specify concepts by their features, both in precise terms as well as vaguely. By repeating the process of specifying the information need and exploring the resulting concepts, the user may precisely single out the concepts that describe his information need. In the second step, the program provides the designations (and variants) for the concepts identified, and connects them by appropriate operators. Dipe-D is meant to improve on existing procedures that identify the concepts less systematically, create a query manually, and then sometimes expand that query. Experiments are reported on each of the two steps; they indicate that the first step identifies only but not all the relevant concepts, and the second step performs (at least) as good as human beings do.     

一种基于词间关联规则挖掘的查询扩展方法

针对现有信息检索系统中存在的词不匹配问题,提出一种基于词间关联规则的查询扩展算法,该算法利用现有挖掘算法自动对前列初检文档进行词间关联挖掘,提取含有原查询词的词间关联规则,从中提取扩展词,实现查询扩展。实验结果表明,该算法能改善和提高信息检索系统的查全率和查准率,具有很高的应用价值,与未进行查询扩展时相比,采用本文查询扩展算法后,平均准确率提高了13.34%,与传统的局部上下文分析查询扩展算法比较,其平均准确率提高了4.87%。     

基于本体和多代理的数字图书馆信息检索模型

在分析图书馆传统的信息检索机制的局限性的基础上,提出了基于本体和多代理的数字图书馆信息检索模型,并介绍了该模型各部分的作用和功能.图3.参考文献3.     

实用型跨语言检索查询翻译接口性能改进研究

针对某网站在线运行的基于词典的查询翻译接口,对接口中实现的3种比较常用的查询翻译消歧算法进行改进,利用性能测试工具Loadrunner对改进前后的查询翻译接口的运行效率进行对比分析,最后总结影响基于词典的查询翻译的运行效率的3个主要因素。     

WWW信息检索系统评介

WWW是目前全球最大的信息系统,本文主要介绍了WWW信息检索系统的分类、WWW信息检索技术、WWW信息检索领域的新成果新思想。结尾阐明WWW信息检索的发展趋势。     

因特网与科技信息检索

因特网对传统的科技信息检索带来了巨大的挑战和冲击,如何利用这一现代化的技术手段进行快速、准确、高效的科技信息检索,是广大专业技术人员和科技情报工作者十分关心的问题.本文通过对网上信息资源的分析,探讨了利用因特网检索科技信息的常用方法和技巧.     

网络信息检索工具评价指标

本文讨论了网络信息环境下 ,传统的信息检索评价指标体系遇到的困难 ,介绍了两位美国研究人员H .VernonLeighton和JaideepSrivastava提出的“相关性范畴”和“前X命中记录查准率”的概念 ,并对他们查准率计算公式做了一些改进。本文的最后对网络信息检索工具的评价指标做了一些讨论。     

关于文献检索课课程体系建设的探讨

本文提出要把在高等学校开设的文献检索课，作为一个贯穿于大学教育全过程并渗透于教学活动方方面面的课程体系来建设。这个课程体系包括：开设文献检索系列课程、开展第一课堂实践活动和开展第二课堂实践活动。同时，还探讨了文献检索课课程体系实施要点和发展前景。     

合作信息查寻与检索的几个问题探析

在信息查寻与检索的全景图谱中探讨合作信息查寻与检索的研究语境,讨论其中英文互译问题,从行为产生、行为实现与行为结果三方面分析其内涵,基于信息检索内在发展需求及外部环境（用户需求与信息技术）分析合作信息查寻与检索研究的起源与发展动力。最后指出研究中应解决的几个核心问题：在用户信息获取谱系中的位置问题、语境功能问题、与传统研究的集成整合问题、机理机制问题、技术方法问题。