期刊文献+
共找到3篇文章
< 1 >
每页显示 20 50 100
道路施工作业区交通流相位分类及应用研究
1
作者 吴培佳 周晨静 +2 位作者 尚永毅 何廷全 刘玉景 《交通工程》 2024年第9期1-8,共8页
为确定施工区交通流相位划分的最优聚类算法,本研究基于三相交通流理论,应用激光雷达、航空摄像等手段采集的施工区交通流运行数据,对PTV-Vissim仿真平台进行标定,搭建6种类型的施工区场景,通过仿真实验得到多样本的施工区交通流数据。... 为确定施工区交通流相位划分的最优聚类算法,本研究基于三相交通流理论,应用激光雷达、航空摄像等手段采集的施工区交通流运行数据,对PTV-Vissim仿真平台进行标定,搭建6种类型的施工区场景,通过仿真实验得到多样本的施工区交通流数据。论文选取层次聚类、高斯混合聚类、光谱聚类、DBSCAN聚类和K-Means聚类5种机器学习算法对施工区的交通流相位进行聚类,建立以轮廓系数、方差比准则和DB指数为基础的综合评分体系,并结合形态学评价方法判断各种聚类算法的优劣,选定层次聚类作为判定施工区交通流相位及其边界划分的最优方法,而后对交通流的相位形态作进一步分析。 展开更多
关键词 施工区 三相交通流 层次聚类法 相位边界 机器学习
下载PDF
边界相位的不确定性对DFB激光器阈值特性的影响
2
作者 沈丹勋 顾畹仪 《激光与红外》 CAS CSCD 北大核心 1999年第2期81-82,84,共3页
应用速率方程及耦合波方程对半导体DFB激光器的边界相位对器件的阈值特性影响进行了分析,并就各模式之间的差异讨论了其对器件的影响。
关键词 DFB激光器 速率方程 耦合波方程 边界相位
下载PDF
Aerothermal characteristics of bleed slot in hypersonic flows 被引量:2
3
作者 YUE LianJie LU HongBo +1 位作者 XU Xiao CHANG XinYu 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS CSCD 2015年第10期46-59,共14页
Two types of flow configurations with bleed their aerodynamic thermal loads and related in two-dimensional hypersonic flows flow structures at choked conditions. are numerically examined to investigate One is a turbul... Two types of flow configurations with bleed their aerodynamic thermal loads and related in two-dimensional hypersonic flows flow structures at choked conditions. are numerically examined to investigate One is a turbulent boundary layer flow without shock impingement where the effects of the slot angle are discussed, and the other is shock wave boundary layer in- teractions where the effects of slot angle and slot location relative to shock impingement point are surveyed. A key separation is induced by bleed barrier shock on the upstream slot wall, resulting in a localized maximum heat flux at the reattachment point. For slanted slots, the dominating flow patterns are not much affected by the change in slot angle, but vary dramatically with slot location relative to the shock impingement point. Different flow structures are found in the case of normal slot, such as a flow pattern similar to typical Laval nozzle flow, the largest separation bubble which is almost independent of the shock position. Its larger detached distance results in 20% lower stagnation heat flux on the downstream slot corner, but with much wider area suffering from severe thermal loads. In spite of the complexity of the flow patterns, it is clearly revealed that the heat flux generally rises with the slot location moving downstream, and an increase in slot angle from 20° to 40° reduces 50% the heat flux peak at the reattachment point in the slot passage. The results further indicate that the bleed does not raise the heat flux around the slot for all cases except for the area around the downstream slot corner. Among all bleed configurations, the slot angle of 40° located slightly upstream of the incident shock is regarded as the best. 展开更多
关键词 boundary layer control boundary layer heat flow shock wave interactions separated flows
原文传递
上一页 1 下一页 到第
使用帮助 返回顶部