长期以来,孤立点的检测一直聚焦于簇边缘的离散点,当聚类后簇的数目低于实际数目,或孤立点被伪装在簇内的情况下,簇内孤立点的判定则会更加困难.为判定簇内孤立点,提出一种基于密度聚类DBSCAN (Density based spatial clustering of app...长期以来,孤立点的检测一直聚焦于簇边缘的离散点,当聚类后簇的数目低于实际数目,或孤立点被伪装在簇内的情况下,簇内孤立点的判定则会更加困难.为判定簇内孤立点,提出一种基于密度聚类DBSCAN (Density based spatial clustering of application with noise)的簇内孤立点检测方法 ODIC-DBSCAN (Outlier detection of inner-cluster based on DBSCAN).首先在建立距离矩阵的基础上,通过半径获取策略得到针对该点集的k个有效半径Radius集合,并据此构造密度矩阵;然后建立点集覆盖模型,提出了相邻有效半径构造的覆盖多维体能够覆盖点集的思想,并通过拉格朗日乘子法求取最优的覆盖多维体数目之比,输出点比阈值组;最后重建ODIC-DBSCAN的孤立点检测方法,以簇发生融合现象作为算法终止的判定条件.实验通过模拟数据集,公开benchmark与UCI数据集共同验证了ODIC-DBSCAN算法,展示了聚类过程;分析了算法性能;并通过与其他聚类、孤立点判定方法的对比,验证了算法对簇内孤立点的判定效果.展开更多
This article presents an experimental investigation on condensation heat transfer of R-134a in horizontal straight and helically coiled tube-in-tube heat exchangers. The experiments were carried out at three saturatio...This article presents an experimental investigation on condensation heat transfer of R-134a in horizontal straight and helically coiled tube-in-tube heat exchangers. The experiments were carried out at three saturation temperatures（35 ℃ , 40 ℃ and 45 ℃ ） with the refrigerant mass flux varying from 100 kg/m2 s to 400 kg/m2 s and the vapor quality ranging from 0.1 to 0.8. The effects of vapor quality and mass flux of R-134a on the condensation heat transfer coefficient were investigated. The results indicate that the condensation heat transfer coefficients of the helical section are 4%-13.8% higher than that of the straight section. The experimental results were compared with the data available in literature for helical and straight pipes.展开更多
文摘长期以来,孤立点的检测一直聚焦于簇边缘的离散点,当聚类后簇的数目低于实际数目,或孤立点被伪装在簇内的情况下,簇内孤立点的判定则会更加困难.为判定簇内孤立点,提出一种基于密度聚类DBSCAN (Density based spatial clustering of application with noise)的簇内孤立点检测方法 ODIC-DBSCAN (Outlier detection of inner-cluster based on DBSCAN).首先在建立距离矩阵的基础上,通过半径获取策略得到针对该点集的k个有效半径Radius集合,并据此构造密度矩阵;然后建立点集覆盖模型,提出了相邻有效半径构造的覆盖多维体能够覆盖点集的思想,并通过拉格朗日乘子法求取最优的覆盖多维体数目之比,输出点比阈值组;最后重建ODIC-DBSCAN的孤立点检测方法,以簇发生融合现象作为算法终止的判定条件.实验通过模拟数据集,公开benchmark与UCI数据集共同验证了ODIC-DBSCAN算法,展示了聚类过程;分析了算法性能;并通过与其他聚类、孤立点判定方法的对比,验证了算法对簇内孤立点的判定效果.
基金the National Natural Science Foundation of China (Grant No. 50376030).
文摘This article presents an experimental investigation on condensation heat transfer of R-134a in horizontal straight and helically coiled tube-in-tube heat exchangers. The experiments were carried out at three saturation temperatures（35 ℃ , 40 ℃ and 45 ℃ ） with the refrigerant mass flux varying from 100 kg/m2 s to 400 kg/m2 s and the vapor quality ranging from 0.1 to 0.8. The effects of vapor quality and mass flux of R-134a on the condensation heat transfer coefficient were investigated. The results indicate that the condensation heat transfer coefficients of the helical section are 4%-13.8% higher than that of the straight section. The experimental results were compared with the data available in literature for helical and straight pipes.
