A pipelined architecture for distributed text query evaluation

Two principal query-evaluation methodologies have been described for cluster-based implementation of distributed information retrieval systems: document partitioning and term partitioning. In a document-partitioned system, each of the processors hosts a subset of the documents in the collection, and executes every query against its local sub-collection. In a term-partitioned system, each of the processors hosts a subset of the inverted lists that make up the index of the collection, and serves them to a central machine as they are required for query evaluation. In this paper we introduce a pipelined query-evaluation methodology, based on a term-partitioned index, in which partially evaluated queries are passed amongst the set of processors that host the query terms. This arrangement retains the disk read benefits of term partitioning, but more effectively shares the computational load. We compare the three methodologies experimentally, and show that term distribution is inefficient and scales poorly. The new pipelined approach offers efficient memory utilization and efficient use of disk accesses, but suffers from problems with load balancing between nodes. Until these problems are resolved, document partitioning remains the preferred method. Alistair Moffat was supported by the Australian Research Council, the ARC Special Research Center for Perceptive and Intelligent Machines in Complex Environments, and the NICTA Victoria Laboratory. William Webber and Justin Zobel were supported by the Australian Research Council. Ricardo Baeza-Yates was supported by Grant P01-029-F from Millennium Initiative of Mideplan, Chile; and by the University of Melbourne as a visiting scholar at the time this project was undertaken.     

India: Demographics for Publishers

The essential demographic data and related information for India is provided specifically for the publishing industry. The focus has been placed on the economics, education and computer industry in relation to the complex cultural factors of different languages and religions. The role of India in relation to the other three BRIC countries or Brazil, China and Russia is explored.     

喧闹与辉煌:网络环境下个人成功模式的构建

本文研究的重点是以网络传播环境为大背景,以网络环境下个人成功模式的构建为切入点,来探讨网络环境和个人成功之间的关系,并提出构建个人成功模式的新途径.     

Searching strategies for the Bulgarian language

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.     

浅论运动队群体效能的发挥

运动队群体效能就是运动队队员整体中潜在的积极作用,群体效能不等于成员之间的简单相加,因为事物在组合过程中可以发生质变。本文就此进行探讨。     

我国体育赞助的现状分析

对体育赞助的概念和作用,我国体育赞助现状进行了分析研究。提出我国目前体育赞助业存在的主要问题有:赞助工作总体状况一般,赞助规模相对较低,赞助对象单一,地区差异大等。对如何发展和规范体育赞助业提出对策建议:健全有关体育赞助的规章制度、加强对体育赞助的宏观规划和调控、加强体育赞助的市场化运作以及教学与科研工作等。     

近十年图书、档案、情报一体化研究综述

对近十年图书、档案、情报一体化研究的几个主要问题进行了论述,包括图书、档案、情报一体化的理论基础,图书、档案、情报一体化的现实条件,一体化管理模式,一体化过程中存在的问题和解决这些问题的对策与方法。