利用常规气象观测资料和NCEP/NCAR逐6 h再分析资料,对2015年11月23—24日山东南部出现的一次罕见特大暴雪天气过程进行诊断分析。结果表明:1)这是一次典型的回流形势降雪,850 h Pa东南风急流影响的鲁南地区降雪强度较大,而东北风急流影...利用常规气象观测资料和NCEP/NCAR逐6 h再分析资料,对2015年11月23—24日山东南部出现的一次罕见特大暴雪天气过程进行诊断分析。结果表明:1)这是一次典型的回流形势降雪,850 h Pa东南风急流影响的鲁南地区降雪强度较大,而东北风急流影响的区域降雪强度较弱。2)700 h Pa强西南低空急流、850 h Pa东南低空急流为鲁南地区降雪提供了充沛的水汽,水汽通量的强辐合区域即为大暴雪的发生区域。3)暴雪区上空散度呈现出弱辐散—强辐合—强辐散的垂直结构;暴雪落区与高空的强辐合中心以及强上升运动中心吻合度较高。4)暴雪期间,850~925 h Pa之间维持一个逆温层;强冷空气使得925 h Pa以下边界层温度锐降导致降雨迅速转雪,降雪持续时间长是鲁南地区产生异常强降雪的重要原因。展开更多
Three-dimensional simulations of diesel particulate matter （DPM） distribution inside a single straight entry for the Load-Haul-Dump loader （LHD）-truck loading and truck hauling operations were conducted by using A...Three-dimensional simulations of diesel particulate matter （DPM） distribution inside a single straight entry for the Load-Haul-Dump loader （LHD）-truck loading and truck hauling operations were conducted by using ANSYS FLUENT computational fluid dynamics software. The loading operation was performed for a fixed period of 3 min. The dynamic mesh technique in FLUENT was used to study the impact of truck motion on DPM distribution. The resultant DPM distributions are presented for the cases when the truck were driving upstream and downstream of the loading face. Interesting phenomena were revealed in the study including the piston effect, layering of DPM in the roof region, and backflow of diesel exhaust against ventilation. The results from the simulation can be used to determine if the areas inside the face area and straight entry exceed the current U.S. regulatory requirement for DPM concentration （〉160 pg/m3）. This research can guide the selection of DPM reduction strategies and improve the working practices for the underground miners.展开更多
文摘利用常规气象观测资料和NCEP/NCAR逐6 h再分析资料,对2015年11月23—24日山东南部出现的一次罕见特大暴雪天气过程进行诊断分析。结果表明:1)这是一次典型的回流形势降雪,850 h Pa东南风急流影响的鲁南地区降雪强度较大,而东北风急流影响的区域降雪强度较弱。2)700 h Pa强西南低空急流、850 h Pa东南低空急流为鲁南地区降雪提供了充沛的水汽,水汽通量的强辐合区域即为大暴雪的发生区域。3)暴雪区上空散度呈现出弱辐散—强辐合—强辐散的垂直结构;暴雪落区与高空的强辐合中心以及强上升运动中心吻合度较高。4)暴雪期间,850~925 h Pa之间维持一个逆温层;强冷空气使得925 h Pa以下边界层温度锐降导致降雨迅速转雪,降雪持续时间长是鲁南地区产生异常强降雪的重要原因。
文摘Three-dimensional simulations of diesel particulate matter （DPM） distribution inside a single straight entry for the Load-Haul-Dump loader （LHD）-truck loading and truck hauling operations were conducted by using ANSYS FLUENT computational fluid dynamics software. The loading operation was performed for a fixed period of 3 min. The dynamic mesh technique in FLUENT was used to study the impact of truck motion on DPM distribution. The resultant DPM distributions are presented for the cases when the truck were driving upstream and downstream of the loading face. Interesting phenomena were revealed in the study including the piston effect, layering of DPM in the roof region, and backflow of diesel exhaust against ventilation. The results from the simulation can be used to determine if the areas inside the face area and straight entry exceed the current U.S. regulatory requirement for DPM concentration （〉160 pg/m3）. This research can guide the selection of DPM reduction strategies and improve the working practices for the underground miners.
