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批量构建M^+-tree 被引量:1
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作者 周项敏 王国仁 +1 位作者 常立 范丹 《小型微型计算机系统》 CSCD 北大核心 2006年第2期295-299,共5页
提出了一种新的M+-tree构造策略—通过批量装载数据静态构造M+-tree.这种建树方法能够极大地降低索引的构建代价并加快建树速度,又能保证高维数据良好的聚类特性.同时又提出了一种有效的聚类算法—多步聚类,基于这种聚类构造M+-tree.实... 提出了一种新的M+-tree构造策略—通过批量装载数据静态构造M+-tree.这种建树方法能够极大地降低索引的构建代价并加快建树速度,又能保证高维数据良好的聚类特性.同时又提出了一种有效的聚类算法—多步聚类,基于这种聚类构造M+-tree.实验结果表明,这种建树算法能够保证索引空间的最大利用率,降低建树的代价,同时又能够保证索引的查询效率. 展开更多
关键词 高维索引 范围查询 最近邻查询 bulk-loading 聚类
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The influence of nozzle diameters on the interaction characteristic of combustion-gas jets and liquid 被引量:1
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作者 Xiao-chun Xue Yong-gang Yu Jin-ming Xie 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2017年第4期257-262,共6页
To investigate the controlling method of interior ballistic stability of bulk-loaded propellant guns,the combustion-gas generator and cylindrical stepped-wall chamber are designed aiming at the injection processes of ... To investigate the controlling method of interior ballistic stability of bulk-loaded propellant guns,the combustion-gas generator and cylindrical stepped-wall chamber are designed aiming at the injection processes of combustion-gases in liquid.The expansion courses of Taylor cavities and the turbulent mixing characteristic of gaseliquid are recorded by means of high speed photographic system.Based on the experiment,three-dimensional unsteady model on the interaction of gas and liquid is established to simulate expansion characteristics of twin combustion-gas jets in liquid under different nozzle diameters.The distribution regularities of characteristic parameter in jet field are obtained and analyzed.The results show the pressure,velocity and temperature distributions under different nozzle diameters are basically the same at the initial time.As time goes on,these characteristic parameters under different nozzle diameters have large differences. 展开更多
关键词 Fluid mechanics Combustion-gases TAYLOR CAVITIES Jet shape bulk-loaded PROPELLANT
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