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基于重心点转移的St-DBSCAN改进算法 被引量:1
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作者 刘勇 何婧 +2 位作者 姚绍文 向毅 张浩 《计算机技术与发展》 2018年第11期6-11,共6页
在目前已提出的聚类算法中,St-DBSCAN算法是一种基于密度且性能优越的时空聚类算法。但是当时空点分布出现密度倾斜时,St-DBSCAN算法会出现聚类时间过长和聚类效果不好的问题。基于此,通过对空间点分布存在的三种数据倾斜,采用数据重心... 在目前已提出的聚类算法中,St-DBSCAN算法是一种基于密度且性能优越的时空聚类算法。但是当时空点分布出现密度倾斜时,St-DBSCAN算法会出现聚类时间过长和聚类效果不好的问题。基于此,通过对空间点分布存在的三种数据倾斜,采用数据重心点转移策略,提出了对应的解决方案,以此实现了改进后的St-DBSCAN算法。为了验证改进后算法的性能,以昆明市出租车GPS数据为实验数据,进行了算法性能对比实验。实验结果表明,改进St-DBSCAN算法的时间性能和聚类效果有了一定程度的提升。 展开更多
关键词 时空聚类算法 St-DBSCAN算法 转移策略 密度倾斜 重心点
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Electric field distribution in 75 kA drained aluminum reduction cell 被引量:2
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作者 李相鹏 李劼 +3 位作者 赖延清 陈江 高增梁 刘业翔 《Journal of Central South University》 SCIE EI CAS 2010年第1期62-67,共6页
Current distribution in a drained aluminum reduction cell is critical due to its influence on the current efficiency, electrolysis stability, anodes and cathodes integrity. A finite element model was developed to simu... Current distribution in a drained aluminum reduction cell is critical due to its influence on the current efficiency, electrolysis stability, anodes and cathodes integrity. A finite element model was developed to simulate the electric field in a 75 kA drained aluminum reduction cell. The current distribution and influences of the cathode inclination angle and anode-cathode distance (ACD) were studied. The results show that relatively large horizontal current density appears in the aluminum film, and the maximum value reaches 600 kA/m2. As the cathode inclination angle increases from 2° to 15°, the maximum current density of the metal pad increases by 15%, while the maximum current density of the aluminum-wettable coating layer decreases by 27%. The influence of the ACD on the current distribution is not obvious. 展开更多
关键词 drained aluminum reduction cell electric field finite element model cathode inclination angle anode-cathode distance
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DIAGNOSTIC VALUE OF DENSITY GRADIENT CENTRIFU-GATION FOR EXFOLIATIVE TUMOR CELLS IN MALIG-NANT PLEURAL EFFUSIONS
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作者 郭胤仕 朱任之 《Journal of Shanghai Second Medical University(Foreign Language Edition)》 2004年第2期118-120,共3页
Objective To find out a specific method for diagnosis of malignant pleural effusions (MPEs)with higher sensitivity and practicality. Methods The diagnosis of MPEs were made using density gradient cen-trifugation(DGC) ... Objective To find out a specific method for diagnosis of malignant pleural effusions (MPEs)with higher sensitivity and practicality. Methods The diagnosis of MPEs were made using density gradient cen-trifugation(DGC) , smear cytologic examination( SCE) and pleural needle biopsy (PNB). Comparisons between these results and those of benign pleural effusions were also made. Results The positive rates of DGC,SCE and PNB for diagnosing MPEs were 94. 3% ,62. 9% and 44. 6% , respectively, and the positive rate of SCE combined with PNB for diagnosing MPEs was 73. 2%. The positive rate of the exfoliative tumor cells ( ETCs ) by DGC was much higher than that of SCE or/and PNB with no false-positive. Conclusion The ETCs isolated by DGC from the MPEs is quite specific for the diagnosis of malignant tumors with higher sensitivity and practicality in clinico-patho-logical practice. 展开更多
关键词 pleural effusion density gradient centrifugation exfoliative cells cytologic examination
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