隐蔽网络及其资源检索策略研究

介绍了隐蔽网络的基本定义,分析了隐蔽网络出现的原因。重点讨论了如何查找隐蔽网络资源。将各种方式总体上划分为间接查找和直接查找两种类型。并介绍了自动利用专业搜索引擎发现隐形网页上资源和构建面向特定任务、人工辅助的网络爬虫两种方法。     

Exploring features for the automatic identification of user goals in web search

Queries submitted to search engines can be classified according to the user goals into three distinct categories: navigational, informational, and transactional. Such classification may be useful, for instance, as additional information for advertisement selection algorithms and for search engine ranking functions, among other possible applications. This paper presents a study about the impact of using several features extracted from the document collection and query logs on the task of automatically identifying the users’ goals behind their queries. We propose the use of new features not previously reported in literature and study their impact on the quality of the query classification task. Further, we study the impact of each feature on different web collections, showing that the choice of the best set of features may change according to the target collection.     

数据检索中索引技术的探讨

设计索引的目的是为了加快数据检索．文章就与索引相关的一些特征元素．提出了创建索引中数据目录项的3种不同方法．同时对B^ 索引进行了描述．分析了其在进行数据搜索的实现原理．简要个绍了在实现数据删除和插入时的优化思路．     

网络教育资源搜索策略研究

将网络教育手段运用于课堂教学中，是教育科研的一个新课题。用好网上教育资源的关键是根据教学科研目的，学会灵活设计检索策略获取资源，将其有机地应用于教学和科研。     

用VB实现文件查找的几种方法

现今电脑硬盘的容量越来越大,其中储存的文件也越来越多.开发能够实现文件快速查找功能的应用程序,必将具有广泛的应用前景.利用VB6.0提供的强大文件操作对象(File System Object),编制了几种切实可行的文件快速查找程序.     

Quality and relevance of domain-specific search: A case study in mental health

When searching for health information, results quality can be judged against available scientific evidence: Do search engines return advice consistent with evidence based medicine? We compared the performance of domain-specific health and depression search engines against a general-purpose engine (Google) on both relevance of results and quality of advice. Over 101 queries, to which the term ‘depression’ was added if not already present, Google returned more relevant results than those of the domain-specific engines. However, over the 50 treatment-related queries, Google returned 70 pages recommending for or against a well studied treatment, of which 19 strongly disagreed with the scientific evidence. A domain-specific index of 4 sites selected by domain experts was only wrong in 5 of 50 recommendations. Analysis suggests a tension between relevance and quality. Indexing more pages can give a greater number of relevant results, but selective inclusion can give better quality.     

Internet上的军事体育信息资源与检索

如何从Internet上获取军事体育信息资源,目前尚未见诸报导。探讨了Internet上军事体育信息资源的分布与检索问题,从军事体育官方网站、军事体育相关网站、网络数据库和搜索引擎等4个方面,阐述了Internet上军事体育信息资源的获取方法。     

Document replication strategies for geographically distributed web search engines

Large-scale web search engines are composed of multiple data centers that are geographically distant to each other. Typically, a user query is processed in a data center that is geographically close to the origin of the query, over a replica of the entire web index. Compared to a centralized, single-center search engine, this architecture offers lower query response times as the network latencies between the users and data centers are reduced. However, it does not scale well with increasing index sizes and query traffic volumes because queries are evaluated on the entire web index, which has to be replicated and maintained in all data centers. As a remedy to this scalability problem, we propose a document replication framework in which documents are selectively replicated on data centers based on regional user interests. Within this framework, we propose three different document replication strategies, each optimizing a different objective: reducing the potential search quality loss, the average query response time, or the total query workload of the search system. For all three strategies, we consider two alternative types of capacity constraints on index sizes of data centers. Moreover, we investigate the performance impact of query forwarding and result caching. We evaluate our strategies via detailed simulations, using a large query log and a document collection obtained from the Yahoo! web search engine.     

试论搜索引擎的现状与发展

随着互联网的不断发展,搜索引擎现在已成为网络用户获取信息的一个不可或缺的检索工具.搜索引擎目前存在诸多问题,例如查全率和查准率、功能问题、作弊问题、安全性问题、信息更新问题、规范化问题等.本文就这些问题进行一些探讨.     

Relevance-based entity selection for ad hoc retrieval

Recent developments have shown that entity-based models that rely on information from the knowledge graph can improve document retrieval performance. However, given the non-transitive nature of relatedness between entities on the knowledge graph, the use of semantic relatedness measures can lead to topic drift. To address this issue, we propose a relevance-based model for entity selection based on pseudo-relevance feedback, which is then used to systematically expand the input query leading to improved retrieval performance. We perform our experiments on the widely used TREC Web corpora and empirically show that our proposed approach to entity selection significantly improves ad hoc document retrieval compared to strong baselines. More concretely, the contributions of this work are as follows: (1) We introduce a graphical probability model that captures dependencies between entities within the query and documents. (2) We propose an unsupervised entity selection method based on the graphical model for query entity expansion and then for ad hoc retrieval. (3) We thoroughly evaluate our method and compare it with the state-of-the-art keyword and entity based retrieval methods. We demonstrate that the proposed retrieval model shows improved performance over all the other baselines on ClueWeb09B and ClueWeb12B, two widely used Web corpora, on the [email protected], and [email protected] metrics. We also show that the proposed method is most effective on the difficult queries. In addition, We compare our proposed entity selection with a state-of-the-art entity selection technique within the context of ad hoc retrieval using a basic query expansion method and illustrate that it provides more effective retrieval for all expansion weights and different number of expansion entities.