核反应堆冷却介质驱动电机是高温气冷堆一回路中的关键设备,作用是将氦气作为冷却介质驱动其在系统中交换热量,为研究冷却介质的流体特性与其在电机内的流体场分布对电机温升甚至整个系统的影响。以一台4 500 k W驱动电机为例,考虑以氦...核反应堆冷却介质驱动电机是高温气冷堆一回路中的关键设备,作用是将氦气作为冷却介质驱动其在系统中交换热量,为研究冷却介质的流体特性与其在电机内的流体场分布对电机温升甚至整个系统的影响。以一台4 500 k W驱动电机为例,考虑以氦气为冷却介质的风磨损耗公式不同于传统公式,对风磨损耗进行重新计算;通过建立该电机通风系统的3D流体场计算模型,基于流体力学原理,采用有限元法得到通风系统内的流体分布;最后,为更好的研究氦气的流体特性,以空气作为对比对象,分析流体性质差异对电机气隙、转子轴向流速和通风沟径向风速分布的影响;结果表明:在相同条件下,氦冷时流体域内各区域流速低于空冷9.4%,有助于减小风磨损耗对电机温升的影响。展开更多
Ventilation system analysis for underground mines has remained mostly unchanged since the Atkinson method was made popular by Mc Elroy in 1935. Data available to ventilation technicians and engineers is typically limi...Ventilation system analysis for underground mines has remained mostly unchanged since the Atkinson method was made popular by Mc Elroy in 1935. Data available to ventilation technicians and engineers is typically limited to the quantity of air moving through any given heading. Because computer-aided modelling, simulation, and ventilation system design tools have improved, it is now important to ensure that developed models have the most accurate information possible. This paper presents a new technique for estimating underground drift friction factors that works by processing 3 D point cloud data obtained by using a mobile Li DAR. Presented are field results that compare the proposed approach with previously published algorithms, as well as with manually acquired measurements.展开更多
This study explores the relationship between socioeconomics and millinery style through an analysis of statistical data from the United States Bureau of Statistics. It was very common for women to wear hats in the ear...This study explores the relationship between socioeconomics and millinery style through an analysis of statistical data from the United States Bureau of Statistics. It was very common for women to wear hats in the early 20th century. Most studies regarding millinery are limited to a discussion of style, while some focus on extended functions of millinery styles such as how they aid in social communication. In this study, we discuss the relationship between a woman＇s socioeconomic status and her hat-wearing behavior. This study covers the period from 1900 through the 1960s, when there was a sudden decline in hat-wearing behavior. We analyzed the changes in the number of people listed in various occupational categories in the U.S. Bureau of Statistics data for each decade. Careful observation of labor distribution statistics for the job market can yield valuable insights about women＇s hat-wearing behaviors. Fluctuations in the population of the lower class were significantly correlated with changes in millinery. We also identified time-sensitive periods in millinery style that coincided with the two World Wars.展开更多
文摘核反应堆冷却介质驱动电机是高温气冷堆一回路中的关键设备,作用是将氦气作为冷却介质驱动其在系统中交换热量,为研究冷却介质的流体特性与其在电机内的流体场分布对电机温升甚至整个系统的影响。以一台4 500 k W驱动电机为例,考虑以氦气为冷却介质的风磨损耗公式不同于传统公式,对风磨损耗进行重新计算;通过建立该电机通风系统的3D流体场计算模型,基于流体力学原理,采用有限元法得到通风系统内的流体分布;最后,为更好的研究氦气的流体特性,以空气作为对比对象,分析流体性质差异对电机气隙、转子轴向流速和通风沟径向风速分布的影响;结果表明:在相同条件下,氦冷时流体域内各区域流速低于空冷9.4%,有助于减小风磨损耗对电机温升的影响。
基金supported by the Natural Sciences and Engineering Research Council of Canada (NSERC) under grant CRDPJ 44580412Barrick Gold Corporation and Peck Tech Consulting Ltd
文摘Ventilation system analysis for underground mines has remained mostly unchanged since the Atkinson method was made popular by Mc Elroy in 1935. Data available to ventilation technicians and engineers is typically limited to the quantity of air moving through any given heading. Because computer-aided modelling, simulation, and ventilation system design tools have improved, it is now important to ensure that developed models have the most accurate information possible. This paper presents a new technique for estimating underground drift friction factors that works by processing 3 D point cloud data obtained by using a mobile Li DAR. Presented are field results that compare the proposed approach with previously published algorithms, as well as with manually acquired measurements.
文摘This study explores the relationship between socioeconomics and millinery style through an analysis of statistical data from the United States Bureau of Statistics. It was very common for women to wear hats in the early 20th century. Most studies regarding millinery are limited to a discussion of style, while some focus on extended functions of millinery styles such as how they aid in social communication. In this study, we discuss the relationship between a woman＇s socioeconomic status and her hat-wearing behavior. This study covers the period from 1900 through the 1960s, when there was a sudden decline in hat-wearing behavior. We analyzed the changes in the number of people listed in various occupational categories in the U.S. Bureau of Statistics data for each decade. Careful observation of labor distribution statistics for the job market can yield valuable insights about women＇s hat-wearing behaviors. Fluctuations in the population of the lower class were significantly correlated with changes in millinery. We also identified time-sensitive periods in millinery style that coincided with the two World Wars.
