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1.
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. 相似文献
2.
Although there has been a great deal of research into Collaborative Information Retrieval (CIR) and Collaborative Information Seeking (CIS), the majority has assumed that team members have the same level of unrestricted access to underlying information. However, observations from different domains (e.g. healthcare, business, etc.) have suggested that collaboration sometimes involves people with differing levels of access to underlying information. This type of scenario has been referred to as Multi-Level Collaborative Information Retrieval (MLCIR). To the best of our knowledge, no studies have been conducted to investigate the effect of awareness, an existing CIR/CIS concept, on MLCIR. To address this gap in current knowledge, we conducted two separate user studies using a total of 5 different collaborative search interfaces and 3 information access scenarios. A number of Information Retrieval (IR), CIS and CIR evaluation metrics, as well as questionnaires were used to compare the interfaces. Design interviews were also conducted after evaluations to obtain qualitative feedback from participants. Results suggested that query properties such as time spent on query, query popularity and query effectiveness could allow users to obtain information about team's search performance and implicitly suggest better queries without disclosing sensitive data. Besides, having access to a history of intersecting viewed, relevant and bookmarked documents could provide similar positive effect as query properties. Also, it was found that being able to easily identify different team members and their actions is important for users in MLCIR. Based on our findings, we provide important design recommendations to help develop new CIR and MLCIR interfaces. 相似文献
3.
Fatemeh Lashkari Ebrahim Bagheri Ali A. Ghorbani 《Information processing & management》2019,56(3):733-755
Traditional information retrieval techniques that primarily rely on keyword-based linking of the query and document spaces face challenges such as the vocabulary mismatch problem where relevant documents to a given query might not be retrieved simply due to the use of different terminology for describing the same concepts. As such, semantic search techniques aim to address such limitations of keyword-based retrieval models by incorporating semantic information from standard knowledge bases such as Freebase and DBpedia. The literature has already shown that while the sole consideration of semantic information might not lead to improved retrieval performance over keyword-based search, their consideration enables the retrieval of a set of relevant documents that cannot be retrieved by keyword-based methods. As such, building indices that store and provide access to semantic information during the retrieval process is important. While the process for building and querying keyword-based indices is quite well understood, the incorporation of semantic information within search indices is still an open challenge. Existing work have proposed to build one unified index encompassing both textual and semantic information or to build separate yet integrated indices for each information type but they face limitations such as increased query process time. In this paper, we propose to use neural embeddings-based representations of term, semantic entity, semantic type and documents within the same embedding space to facilitate the development of a unified search index that would consist of these four information types. We perform experiments on standard and widely used document collections including Clueweb09-B and Robust04 to evaluate our proposed indexing strategy from both effectiveness and efficiency perspectives. Based on our experiments, we find that when neural embeddings are used to build inverted indices; hence relaxing the requirement to explicitly observe the posting list key in the indexed document: (a) retrieval efficiency will increase compared to a standard inverted index, hence reduces the index size and query processing time, and (b) while retrieval efficiency, which is the main objective of an efficient indexing mechanism improves using our proposed method, retrieval effectiveness also retains competitive performance compared to the baseline in terms of retrieving a reasonable number of relevant documents from the indexed corpus. 相似文献
4.
学位论文资源的开发与利用 总被引：3，自引：0，他引：3
赵稚平 《黄河科技大学学报》2004,6(3):148-151
学位论是学位制的产物,是高等院校学生为获得某种学位而撰写的科学论。学位论是具有学术价值、情报价值的重要信息资源,应认真开发和利用。 相似文献
5.
张泽鸿 《江西师范大学学报(哲学社会科学版)》2006,39(1):17-22
陶渊明诗文中显示诗人独特的人生境界理想,表现出四大范型,即:追慕生命的原初境界;重返生命的自由境界;创造生命的幽远境界以及归依生命的宇宙境界。诗人的人生境界观,既是文化理想,也是人生境界的审美范型,具有现代性的人文关怀精神和价值启示意义。 相似文献
6.
针对传统的基于Web图的垂直搜索策略Authorities and Hubs,提出了一种融合了网页内容评价和Web图的启发式垂直搜索策略,此外,引入向量空间模型进行针对网页内容的主题相关度判断,进一步提高主题网页下载的准确率.实验表明,文中算法有效地提高了主题网页的聚合程度,且随着网页下载数量的增加,垂直搜索引擎的准确率逐渐递增,并在下载网页达到一定数量后,准确率趋于稳定,算法具有较好的鲁棒性,可以应用到相关垂直搜索引擎系统中. 相似文献
7.
随着地理信息系统(GIS)应用的逐步深入和业务领域的拓展,传统的GIS数据模型不能较好地表达GIS中复杂的空间数据关系,不易实现数据的共享和查询.为此,文中首先构建了一种网络数据抽象模型,该模型能够使异质的、松散的被关联的GIS数据聚集在一起,且是动态更新以提高将来的查询性能;然后提出一种基于此模型的动态检索算法. 相似文献
8.
龙其林 《南阳师范学院学报》2012,11(5):79-81
阿宁的长篇小说《能耐》从消费时代的心灵困境着手,揭示了两个处于社会不同阶层的家庭在遭遇困厄时的精神变迁与灵魂感悟。小说着力于捕捉物质年代消费文化对于人性的异化,对承受身体与精神困境双重压力的x．．4rl的灵魂状态及自我救赎进行了生动的表现。 相似文献
9.
文章介绍了搜索引擎网页快照系统的实现以及在安全性能方面的研究。当前的多数搜索引擎网站提供的网页快照,能够使用户更加快速和方便地访问较早时期的网页,但它们并没有对其中的网页安全进行判断。文章中的网页快照系统在实现网页快照的同时,通过建立网页脚本语言学习解释器,运用机器学习技术、词法分析技术等对网页上可能存在的不安全代码进行判断和去除,从而保证提供给用户的是尽量安全的网页快照。 相似文献
10.
李春尧 《科学．经济．社会》2014,(1):33-38,43
本文以《护生画集》和丰子恺先生的散文作品为资料,从佛心、童心、仁心三个角度剖析了丰先生"护生即护心"的思想。本文认为,"护生即护心"是丰先生护生思想的主旨和中心论点,这一观点是佛教教义和中国传统哲学交融的结晶,从一个侧面体现了佛学与中国传统哲学的融合。这一观点立足于佛教又不拘泥于佛教,融汇了儒学又超越了儒学,诉诸于童心更深化了童心。本文还分析总结了护生思想的现代意义,认为它在继承发扬佛教伦理、回应人类中心主义论争等问题上都有很大的理论价值。 相似文献