Extensions to the STAIRS Study—Empirical Evidence for the Hypothesised Ineffectiveness of Boolean Queries in Large Full-Text Databases     

Eero Sormunen 《Information Retrieval》2001,4(3-4):257-273

The STAIRS study conducted by Blair and Maron in the mid-80's is a milestone in the history of IR evaluation. Blair and Maron made strong conclusion about the inadequacy of free-text searching large databases, and their study has been widely referred in the literature to justify the problems of effectiveness in IR systems. However, some critics of the study have plausibly pointed out that the ineffectiveness conclusions were not solidly based on empirical data.This paper introduces a new theoretical and empirical approach to study the problems of high recall searching in large databases and reports the results of a case experiment. The findings verify some of the hypothetical conclusions introduced in the STAIRS study, and expands the picture of falling performance. It is shown that low precision in high recall searching is unavoidable in exact-match Boolean searching since even major concepts are often expressed implicitly in relevant documents. The author suggests that the problem could be reduced in facet-based best-match searching.  相似文献   

基于用户信息需求的元搜索引擎的构建   总被引：5，自引：0，他引：5  

韩毅 《图书情报工作》2005,49(1):125-127

针对当前网络搜索引擎未能较多地关注用户需求、查全率与查准率不高、彼此间不兼容的缺陷,提出建立基于用户需求的元搜索引擎,并分析其基本原理,给出其基本结构,讨论其运行机制和关键技术。指出基于用户需求的元搜索引擎可使网络信息资源在一定程度上结构化,实现网络信息资源的自组织,提高网络信息检索的查全率和查准率.  相似文献   

The IR Has Two Faces: Positioning Institutional Repositories for Success     

John Novak  Annette Day 《New Review of Academic Librarianship》2018,24(2):157-174

This article describes the ongoing efforts at University of Nevada, Las Vegas (UNLV) Libraries to evolve the role of the institutional repository (IR) and to effectively position it within the context of the Libraries’ collections, research support, and scholarly communication services. A major component of this process is re-examining the fundamental aims of the IR and aligning it to the Libraries and the campus strategic goals. The authors situate UNLV Libraries’ experience within the context of the current literature to provide background and reasoning for our decision to pursue two, at times conflicting, aims for the IR: one for scholarly communication and another for research administration.  相似文献   

世界主义的价值诉求——国际关系规范理论的视角   总被引：2，自引：0，他引：2  

张旺 《教学与研究》2006,103(12):60-66

世界主义是一种具有悠久传统的哲学理念,它主张世界是一个单一的共同体,所有人皆为其中的平等成员。近年来随着国际关系规范理论的复兴,世界主义再次走向前台。在当前全球化的背景下,面对国际政治、经济秩序的重大变迁,一系列关乎人类命运问题的显现,以个人主义的价值前提和全球共同体的道德理想为基础,世界主义在人权的普遍性、全球范围的分配正义和世界主义民主等不同领域都表达了自己的道德诉求。然而,作为一种普遍性的价值目标,其在具体实施过程中可能产生的负面影响同样不容忽视。  相似文献   

一类Henstock可积而非Lebesgue可积的函数     

王璞杰 《天津工程师范学院学报》2001,11(4):8-10

通过讨论(L)积分、(IR)积分及(H)积分三者的关系,给出一类(H)可积而非(L)可积的函数.  相似文献   

红外光谱法确认辽宁三地区苹果中黄烷醇类化合物     

侯冬岩  回瑞华  关崇新  王婧楠 《鞍山师范学院学报》2001,3(1):91-94

黄烷醇基本结构为C6·C3·C6型化合物 ,具有一定的抗癌活性 .其衍生形成的多酚类化合物对人体具有较强的抗衰老作用 ,它广泛存在于各种水果及一些植物中 .本文利用红外光谱法对辽宁三地区不同种类苹果的提取物进行了分析、比较 ,结果是辽南地区的苹果黄烷醇类化合物的含量少于辽西地区的苹果黄烷醇类化合物的含量 ,富士苹果的黄烷醇类化合物的含量高于国光苹果的黄烷醇类化合物的含量 ,为进一步研究开发提供了依据  相似文献   

Searching strategies for the Bulgarian language     

Jacques Savoy 《Information Retrieval》2007,10(6):509-529

This paper reports on the underlying IR problems encountered when indexing and searching with the Bulgarian language. For this language we propose a general light stemmer and demonstrate that it can be quite effective, producing significantly better MAP (around + 34%) than an approach not applying stemming. We implement the GL2 model derived from the Divergence from Randomness paradigm and find its retrieval effectiveness better than other probabilistic, vector-space and language models. The resulting MAP is found to be about 50% better than the classical tf idf approach. Moreover, increasing the query size enhances the MAP by around 10% (from T to TD). In order to compare the retrieval effectiveness of our suggested stopword list and the light stemmer developed for the Bulgarian language, we conduct a set of experiments on another stopword list and also a more complex and aggressive stemmer. Results tend to indicate that there is no statistically significant difference between these variants and our suggested approach. This paper evaluates other indexing strategies such as 4-gram indexing and indexing based on the automatic decompounding of compound words. Finally, we analyze certain queries to discover why we obtained poor results, when indexing Bulgarian documents using the suggested word-based approach.  相似文献   

国内机构知识库研究进展   总被引：15，自引：0，他引：15  

邓君  毕强 《图书与情报》2007,(5):37-42

文章分析了国内机构知识库（Institutional Repository）理论研究现状以及实践发展，重新界定了机构知识库的涵义，指出目前国内学者在服务模式、相关法律问题以及内容质量控制等机构知识库发展实际应用方面的研究不足，并根据机构知识厍发展方向，从内容建设、标准化建设、资源长期保存与可持续发展、系统和内容评价与政策支持、软件系统汉化应用以及内容版权许可等方面论述展望了未来机构知识厍的研究趋势。  相似文献   

社交网络舆情下的二元信息竞争SH2IR模型及仿真研究     

靖鲲鹏  岑怡 《情报杂志》2022,(1)

[研究目的]网络舆情中信息间的竞争传播更符合社交网络的真实情境,研究舆情事件中多元信息竞争传播的演化机制有助于政府和媒体有效监控舆情、引导舆论。[研究方法]结合舆情事件多信息传播特点,加入信息犹豫者和信息接触率,构建二元信息竞争的SH2IR模型,仿真同步和异步情景下二元信息的竞争演化过程。[研究结论]研究表明,在同步传播模式下,单独增强信息接触率、传播转化率、犹豫转化率以及置换率,都可以扩大信息的传播;在异步传播模式下,信息发布的越早,传播范围越广,但单独增强传播参数对传播效果影响较弱,同时提高信息的传播参数时传播行为明显加强。  相似文献   

加强机构知识库内容建设的探索与实践     

李永芳  邓红  丁君涛 《大学图书情报学刊》2014,(4):21-24

文章总结了目前机构知识库内容建设面临的困难和提出的各种解决方法,并结合北京工业大学实际,在深入了解机构人员对机构知识库想法的基础上,围绕着如何增加机构知识库的实用性,进而引发机构人员对机构知识库的关注并加强与图书馆的主动配合这一核心问题,有针对性地提出了加强机构知识库内容建设的几个举措,指出了实践过程中遇到的问题并提出相应的解决办法。  相似文献