A case study of distributed information retrieval architectures to index one terabyte of text

The increasing number of documents to be indexed in many environments (Web, intranets, digital libraries) and the limitations of a single centralised index (lack of scalability, server overloading and failures), lead to the use of distributed information retrieval systems to efficiently search and locate the desired information. This work is a case study of different architectures for a distributed information retrieval system, in order to provide a guide to approximate the optimal architecture with a specific set of resources. We analyse the effectiveness of a distributed, replicated and clustered architecture simulating a variable number of workstations (from 1 up to 4096). A collection of approximately 94 million documents and 1 terabyte (TB) of text is used to test the performance of the different architectures. In a purely distributed information retrieval system, the brokers become the bottleneck due to the high number of local answer sets to be sorted. In a replicated system, the network is the bottleneck due to the high number of query servers and the continuous data interchange with the brokers. Finally, we demonstrate that a clustered system will outperform a replicated system if a high number of query servers is used, essentially due to the reduction of the network load. However a change in the distribution of the users’ queries could reduce the performance of a clustered system.     

探讨几种物理量的指数方法在强降水预报中的应用

本文通过现有的MICAPS提供的几种物理量和实况降水资料来分析近几年出现的强降水天气,找到一组相关的K指数、不稳定能量、沙氏指数与强降水相对应的指标,来作为预报强降水天气的辅助工具.     

我国电站设备企业国际竞争力指标体系分析

在经济全球化环境下,市场竞争愈加激烈,如何提高企业国际竞争力成为一个亟待解决的问题。首先简要分析国内外电站设备企业的发展情况,界定了电站设备企业国际竞争力的基本内涵,分析影响我阁电站设备企业发展的主要因素,在此基础上进行评价指标体系的设计,从而为我国电站设备企业提高国际竞争力提供理论和实践的指导作用。     

基于知识产权资本本性的价值评估

知识产权的独创性、垄断性等特征,使知识产权价值无法以传统的社会必要劳动时间来判断。既然劳动创造了价值,那么以统一的社会必要劳动时间为恒定的参照值,以知识产权增值能力,即知识产权运用所能解放的劳动时间或劳动量来量化知识产权价值,从而在传统价值论基础上,基于知识产权资本本性发展了劳动价值论。     

北京市"三城一区"动态监测指标体系的构建研究

构建北京市"三城一区"动态监测指标体系对指导现阶段北京市建设全国科技创新中心主平台,促进北京市产学研互动、南北城协调发展,进一步实现人才战略调整和产业结构的升级转型具有深远意义.本文基于"三城一区"规划发展现状及相关规划区的横向比较,通过深度梳理国内外创新指标体系的理论与实践研究,采用共性指标与特色指标相结合的方式构建了评价"三城一区"规划目标完成度的动态监测指标体系.具体而言,借鉴典型创新能力指标体系的构建原则遴选确定共性指标,结合各区战略定位和自身发展规划确定各区域的特色指标,并同时考虑了"三城一区"的协同联动.北京市"三城一区"动态监测框架能全面反映规划区域创新能力水平,为北京市创新优劣分析以及完成度评价提供新的参考.