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列存储数据库关键技术综述 被引量:24
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作者 李超 张明博 +1 位作者 邢春晓 胡劲松 《计算机科学》 CSCD 北大核心 2010年第12期1-7,17,共8页
随着互联网技术的发展、硬件的不断更新、企业及政府信息化的不断深入,应用的复杂性要求越来越高,推动着数据存储技术向着海量数据、分析数据、智能数据的方向发展,以便为数据仓库、在线分析提供高效实时的技术支持。基于行存储的数据... 随着互联网技术的发展、硬件的不断更新、企业及政府信息化的不断深入,应用的复杂性要求越来越高,推动着数据存储技术向着海量数据、分析数据、智能数据的方向发展,以便为数据仓库、在线分析提供高效实时的技术支持。基于行存储的数据库技术面临新的问题,已经出现了技术瓶颈。近些年来,一种新的数据存储理念,即基于列存储的关系型数据库(简称列数据库,下同)应运而生。列数据库能够快速发展,主要原因是其复杂查询效率高,读磁盘少,存储空间少,以及由此带来的技术、管理和应用优势。对列数据库技术的基本现状、关键支撑技术以及应用优势进行了介绍和分析。 展开更多
关键词 列数据库 列存储 数据压缩 延时物化 成组迭代 不可见连接 数据仓库 商业智能 TPCH
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Joint Optimization on Energy and Delay for Target Tracking in Internet of Things 被引量:4
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作者 黎羴 范春晓 《China Communications》 SCIE CSCD 2011年第1期20-27,共8页
Network and communications models are built for target tracking and pursuing in the Internet of Things (IoT).According to these models,two tracking schemes which jointly optimize the pursuing energy and delay are prop... Network and communications models are built for target tracking and pursuing in the Internet of Things (IoT).According to these models,two tracking schemes which jointly optimize the pursuing energy and delay are proposed.The merits of these schemes are that they can enhance energy efficiency of both the pursuing route and communication in the network.Moreover,experimental results are provided to demonstrate the benefits of the proposed schemes which will be used as optimization schemes for the IoT tracking service. 展开更多
关键词 Internet of Things sensor network target tracking ROUTING DELAY
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Coefficient of retardation time found out by polynomial fitting to predict creep behaviour of polystyrene
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作者 谢刚 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2005年第1期44-47,共4页
The universal creep function is successful in relating the creep (ε) to the ageing time (ta), coefficient of retardation time (β), and intrinsic time (t0). The relation was used to treat the creep experiment... The universal creep function is successful in relating the creep (ε) to the ageing time (ta), coefficient of retardation time (β), and intrinsic time (t0). The relation was used to treat the creep experimental data for polystyrene (PS) specimens at a given aged time and different stress levels. Comparing with “middle-point” method reported in the literatures, β is found out by another method “polynomial fitting” in this work. Then unified master lines were constructed with the treated data and curves according to the universal equation. The master lines can be used to predict the long-term creep behaviour and lifetime by extrapolating to a required ultimate strain. 展开更多
关键词 polystyrene(PS) PREDICT creep coefficient of retardation time united master line
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