Query expansion with terms selected using lexical cohesion analysis of documents

We present new methods of query expansion using terms that form lexical cohesive links between the contexts of distinct query terms in documents (i.e., words surrounding the query terms in text). The link-forming terms (link-terms) and short snippets of text surrounding them are evaluated in both interactive and automatic query expansion (QE). We explore the effectiveness of snippets in providing context in interactive query expansion, compare query expansion from snippets vs. whole documents, and query expansion following snippet selection vs. full document relevance judgements. The evaluation, conducted on the HARD track data of TREC 2005, suggests that there are considerable advantages in using link-terms and their surrounding short text snippets in QE compared to terms selected from full-texts of documents.     

拟合用户偏好的个性化搜索

文章从用户偏好的角度对个性化搜索进行了优化研究,提出了基于语义关联树的查询扩展算法以及基于该算法的拟合用户偏好的个性化搜索系统架构。语义关联树可以灵活有效地控制查询扩展模型,在此之上的拟合用户偏好的个性化搜索系统具有用户偏好自学习能力。实验证明,该方法能有效提高文本检索的准确率。     

浅谈图书馆社区信息服务的推广

图书馆的社区信息服务将是一个颇具发展潜力和广阔前景的新领域，值得图书馆界大力推广。推广社区信息服务应从以下入手；（1）利用图书馆立法；（2）争取政府支持，主管领导重视；（3）健全管理体制，引入激励机制；（1）沟通社区关系；（5）扩大服务对象和范围；（6）提高队伍素质；（7）强化读者服务意识；（8）举办各种社区活动。     

The Co-Effects of Query Structure and Expansion on Retrieval Performance in Probabilistic Text Retrieval

The effects of query structures and query expansion (QE) on retrieval performance were tested with a best match retrieval system (InQuery¹). Query structure means the use of operators to express the relations between search keys. Six different structures were tested, representing strong structures (e.g., queries with facets or concepts identified) and weak structures (no concepts identified, a query is a bag of search keys). QE was based on concepts, which were first selected from a searching thesaurus, and then expanded by semantic relationships given in the thesaurus. The expansion levels were (a) no expansion, (b) a synonym expansion, (c) a narrower concept expansion, (d) an associative concept expansion, and (e) a cumulative expansion of all other expansions. With weak structures and Boolean structured queries, QE was not very effective. The best performance was achieved with a combination of a facet structure, where search keys within a facet were treated as instances of one search key (the SYN operator), and the largest expansion.     

我国书业企业扩张策略探讨

本文从我国书业企业战略扩张的实际需要出发,探讨了我国书业企业进行扩张的六个策略,以期能为书业企业的战略扩张行为提供决策参考.     

A new patch antenna with metamaterial cover

INTRODUCTION Investigation of metamaterials is currently one of the most active frontiers in engineering and physics. Metamaterials are also called backward-wave mate- rials, double-negative materials, or left-handed mate- rials. Left-handed materials were proposed by Vese- lago (1968). The applications of metamaterials are widely spread in many fields (Pendry, 2000; Grbic and Eleftheriades, 2003; Foteinopoulou et al., 2003), such as imaging apparatus, planar light wave circuits, optica…     

中国经济稳步进入新一轮景气状态

本文讨论了目前中国经济通货紧缩的国内外经济主导力量及其近期显著的演化趋势。在此基础上,我们对中国宏观经济包括经济增长,通货膨胀以及国际收支等变量的近期演变进行了分析,并给出了今明两年的相关预测结果。     

钢筋锈胀下的混凝土抗压强度试验研究

通过快速锈蚀试验和ABAQUS软件分析对比的方式对钢筋锈蚀膨胀中的混凝土抗压强度进行了研究,提出了对混凝土内部施加温度场的方法模拟钢筋产生的锈蚀膨胀力;分析结果表明,混凝土在钢筋临界锈蚀时混凝土强度会发生较大程度的下降。     

社会化网络服务的开放运行架构及服务拓展研究

网络服务的社会化已成为其发展趋势,不仅带来了用户需求的变革,而且推进了信息服务的研究与应用。在简要梳理社会化网络服务发展脉络的基础上,重点分析了社会化网络服务的开放运行架构,包括其平台基础和平台延伸;然后结合当前社会化网络服务应用的开展情况,阐述了其融合集成的服务拓展体系,包括社会化信息服务、社会化生活服务和社会化商务服务。最后总结归纳了社会化网络服务的多元化、开放化、智能化发展趋势。     

微小长度变化量的实验研究

总结了光杠杆放大法、千分表测量法、光的干涉测量法和光的衍射测量法测量微小长度变化量的方法,通过对实验装置进行相应的改造与组装,并用其测量原理和方法以及相关的实验装置对金属受热时的微小伸长量及线胀系数进行了相应的测定,同时对实验结果和误差进行了比较与分析。实验表明,4种测量方法中千分表测量法的相对误差和标准偏差均接近最小值,是4种方法中最理想的测量方法。该实验也有利于激发学生的创新意识,培养他们的研究潜能。