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   

近几年来国外信息检索模型研究进展   总被引：2，自引：0，他引：2  

孙坦  周静怡 《图书馆建设》2008,(3):82-85

信息检索模型是信息检索的核心.近几年来国外对于布尔模型的研究主要表现在对布尔模型的改进及对扩展布尔模型的进一步优化.对向量空间模型的研究,主要集中在对向量空间模型的扩展研究及对向量空间模型的应用方面.概率模型的发展主要集中在继续对概率模型进一步的研究,其与其它信息检索模型的结合,以及语言模型的研究和发展.近年来对于新兴的基于本体的信息检索模型的研究,主要集中在对基于本体的信息检索模型理论的研究,与其它检索模型的融合,以及基于本体检索模型的应用.国外信息检索模型研究的最新成果,为国内此方面的研究提供了前沿性的参考信息.  相似文献   

二进数布尔代数的几个应用结果     

吕瑞芳  蒋忠樟 《金华职业技术学院学报》2002,2(1):39-40,43

本文讨论了二进数所成的布尔代数以及它与X幂集P(X)所成的布尔代数之间的同构关系，利用其解决关于子集的交集、并集的计数问题，关于交错k-子集的计数问题和关于交错R-子集的计数定理。  相似文献   

关于R0代数的布尔元     

王保社 《咸阳师范学院学报》2004,19(4):11-13

研究了每一个元都是布尔元的R0代数，用等式刻划了其特征，证明了如下结果：R0代数M的每一个元都是布尔元的充要条件是M为布尔代数。并给出一个反例说明：R0代数的所有布尔元一般不能构成MP滤子。  相似文献   

Enhanced teaching and student learning through a simulator-based course in chemical unit operations design     

Nayef Ghasem 《European Journal of Engineering Education》2016,41(4):455-467

This paper illustrates a teaching technique used in computer applications in chemical engineering employed for designing various unit operation processes, where the students learn about unit operations by designing them. The aim of the course is not to teach design, but rather to teach the fundamentals and the function of unit operation processes through simulators. A case study presenting the teaching method was evaluated using student surveys and faculty assessments, which were designed to measure the quality and effectiveness of the teaching method. The results of the questionnaire conclusively demonstrate that this method is an extremely efficient way of teaching a simulator-based course. In addition to that, this teaching method can easily be generalised and used in other courses. A student's final mark is determined by a combination of in-class assessments conducted based on cooperative and peer learning, progress tests and a final exam. Results revealed that peer learning can improve the overall quality of student learning and enhance student understanding.  相似文献   

Improving the learning of Boolean queries by means of a multiobjective IQBE evolutionary algorithm     

O. Cordón  E. Herrera-Viedma  M. Luque 《Information processing & management》2006

The Inductive Query By Example (IQBE) paradigm allows a system to automatically derive queries for a specific Information Retrieval System (IRS). Classic IRSs based on this paradigm [Smith, M., & Smith, M. (1997). The use of genetic programming to build Boolean queries for text retrieval through relevance feedback. Journal of Information Science, 23(6), 423–431] generate a single solution (Boolean query) in each run, that with the best fitness value, which is usually based on a weighted combination of the basic performance criteria, precision and recall.  相似文献   

对提升高职院校校内实训基地管理运营效率的思考     

申屠江平 《金华职业技术学院学报》2011,11(1):1-5

高职院校校内实训基地普遍存在实训效益不佳、对外服务运营不力、设备利用率不高等问题,其根本原因在于重建轻管、重硬件投入轻软件建设。只有建立统一领导、分级管理的运营机制,打造结构合理、能教善做的实训教学团队,深化校企合作、加强工学结合,才能提高管理运营效率,实现校内实训基地的自我运作、自我建设和自我发展。  相似文献   

一种新的H-CgCr肤色模型的肤色检测方法     

汤三 《许昌学院学报》2011,30(5):73-77

提出一种新的H-CgCr肤色模型进行肤色检测,该模型充分利用色调和色度信息区分肤色像素和非肤色像素.并利用形态学操作去除检测出皮肤区域中毛刺、空洞等噪声.实验结果表明该方法在复杂光照条件下能有效检测出肤色区域.  相似文献   

可持续发展下的制造企业商业模式创新:闭环产品服务系统     

刘宇熹  谢家平 《科学学与科学技术管理》2015,(1)

再制造与产品服务系统是制造企业提升竞争力、实现可持续发展的两个有效手段,前者通过高级形式的循环利用直接实现资源的节约减量化,后者则以服务提供的方式间接减少资源的消耗。然而,如同较高的技术和市场门槛限制了再制造的发展一样,产品与服务的设计、整合提供能力也影响着产品服务系统的实施。那么,再制造与产品服务融合的边界在哪里?企业该如何设计并实施可持续发展下的产品服务组合商业模式?融合再制造与产品服务提出闭环产品服务系统,并从交易费用角度对闭环产品服务系统的形成机理与内涵、运营要素进行深入分析。  相似文献   

MBA“运营管理”教学面临的困惑与思考     

张聪群  李宏宇 《宁波大学学报(教育科学版)》2015,(1):68-72

“运营管理”是MBA的核心课程之一。MBA“运营管理”教学面临研究对象的变化与教材内容体系的混乱、MBA 学员背景的差异与需求的多元化、网络信息技术对企业运营系统与运营活动的影响等困惑,直接影响MBA“运营管理”课程的教学效果。MBA“运营管理”课程可以从课程内容拆分、制造企业运营与服务企业运营分离、学员根据工作需要选修等措施进行尝试性的改革与探索。  相似文献