期刊文献+
共找到2篇文章
< 1 >
每页显示 20 50 100
基于可扩展精度的Logistic混沌随机序列的并行计算方法 被引量:9
1
作者 刘嘉辉 张宏莉 《中国科学技术大学学报》 CAS CSCD 北大核心 2011年第9期837-846,共10页
在有限计算精度下的混沌特性退化问题一直是困扰数字混沌系统的关键问题.采用可扩展精度并行方法计算Logistic映射,对混沌函数进行分步计算,利用动态数组保存计算结果.基于可扩展精度计算混沌,打破了计算机内有限精度的限制,用户可以自... 在有限计算精度下的混沌特性退化问题一直是困扰数字混沌系统的关键问题.采用可扩展精度并行方法计算Logistic映射,对混沌函数进行分步计算,利用动态数组保存计算结果.基于可扩展精度计算混沌,打破了计算机内有限精度的限制,用户可以自由指定计算精度.实验结果表明,基于可扩展精度的混沌随机数列,随着精度的增加,映射空间扩大,得到的混沌序列更加接近于理想的混沌状态. 展开更多
关键词 可扩展精度 随机数列 并行算法 LOGISTIC映射
下载PDF
MEXIR: An Implementation of High Performance and High Precision on XML Retrieval
2
作者 Tanakom Wichaiwong Chuleerat Jaruskulchai 《Computer Technology and Application》 2011年第4期301-310,共10页
Traditional information retrieval systems respond to user queries with ranked lists of relevant documents. Since, XML (Extensible Markup Language) documents separate content and structure; XML-IR (information retri... Traditional information retrieval systems respond to user queries with ranked lists of relevant documents. Since, XML (Extensible Markup Language) documents separate content and structure; XML-IR (information retrieval) systems are able to retrieve only the relevant portions of documents. Therefore, users who utilize an XML-IR system could potentially receive highly relevant and precise material. We have developed the XML information retrieval system by using MySQL and Sphinx, which we call MEXIR. In our system, XML documents are stored into one table that has fixed relational schema. The schema is independent of the logical structure of XML documents. Each node in XML documents is represented by labels that express the positions in XML tree, namely ADXPI scheme. Our system has performance experiments on INEX collections and shown an average up to four seconds better than GPX. In addition, it has been reduced the size of the data down by 82.29 % compare to GPX system. 展开更多
关键词 XML retrieval information retrieval ranking strategies indexing units.
下载PDF
上一页 1 下一页 到第
使用帮助 返回顶部