To overcome the disadvantages of displacement ventilation( DV) and traditional mixing ventilation( MV) system,a new ventilation system known as impinging jet ventilation system( IJVS)has been developing. The warm air ...To overcome the disadvantages of displacement ventilation( DV) and traditional mixing ventilation( MV) system,a new ventilation system known as impinging jet ventilation system( IJVS)has been developing. The warm air can be supplied with impinging jet ventilation( IJV), while the DV is only used for cooling.However,the flow and temperature field of IJV under heating scenario has had few references. The paper is mainly focused on computational fluid dynamics( CFD) and developing an adequate correlation between the distance L that warm air can reach and different parameters in the warm IJVS by using response surface methodology( RSM). The results indicate that L decreases as the supply velocity υ decreases but increases as the supply temperature difference ΔT or the discharge height h decreases. In the variable air volume( VAV) system, it is necessary to determine supply parameters both under the maximum-heat-load condition and the small-heat-load condition. Unlike the VAV system,the constant air volume( CAV) system has no need to study the small-heat-load condition. Draught discomfort near the nozzle becomes the issue of concern in IJVS, thus the suitable discharge height is of great importance in design and can be calculated based on the predictive model.展开更多
This paper attempts to reveal a long-distance-relayed water vapor transport(LRWVT) east of Tibetan Plateau and its impacts. The results show that from August to October, east of Tibetan Plateau, there exists a unique ...This paper attempts to reveal a long-distance-relayed water vapor transport(LRWVT) east of Tibetan Plateau and its impacts. The results show that from August to October, east of Tibetan Plateau, there exists a unique LRWVT,and the water vapor from the South China Sea and the western Pacific can affect the Sichuan Basin, Northwest China and other Chinese regions far from the tropical sea through this way. From August to October, the precipitation of the region east of the Plateau is closely linked both in the intra-annual and inter-annual variations, and the LRWVT from the South China Sea and the western Pacific is an important connection mechanism. The large-scale circulation background of the LRWVT impacting the precipitation of the region east of the Plateau is as follows: At high levels,the South Asian High is generally stronger than normal and significantly enhances with its northward advance and eastward extension over the region east of the Plateau. At mid-level, a broad low pressure trough is over Lake Balkhash and its surroundings, and the Western Pacific Subtropical High(WPSH) is northward and westward located, and the western part of Sichuan Basin and the eastern part of Northwest China are located in the west and northwest edge of WPSH.展开更多
Connes' distance formula is applied to endow linear metric to three 1D lattices of different topologies with a generalization of lattice Dirac operator written down by Dimakis et al.to contain a non-unitary link-v...Connes' distance formula is applied to endow linear metric to three 1D lattices of different topologies with a generalization of lattice Dirac operator written down by Dimakis et al.to contain a non-unitary link-variable.Geometric interpretation of this link-variable is lattice spacing and parallel transport.展开更多
Atmospheric lifetimes and traveling distances of 15 PAHs(Ac:acenaphthylene,Ace:acenaphthene,Ph:phenanthrene,MePh3:3-methyl-phenanthrene,MePh9:9-methyl-phenanthrene,MePh1:1-methyl-phenanthrene,MePh2:2-methyl-phenanthre...Atmospheric lifetimes and traveling distances of 15 PAHs(Ac:acenaphthylene,Ace:acenaphthene,Ph:phenanthrene,MePh3:3-methyl-phenanthrene,MePh9:9-methyl-phenanthrene,MePh1:1-methyl-phenanthrene,MePh2:2-methyl-phenanthrene,Ret:retene,B[a]A:benzo[a]anthracene,Chry:chrysene,B[b,j,k]F:benzo[b,j,k]fluoranthene,B[e]P:benzo[e]pyrene,B[a]P:benzo[a]pyrene,Ind:indeno[1,2,3-cd]pyrene,B[g,h,i]P:benzo[g,h,i]perylene)at Whitbourne,UK,were estimated by using the rate constants for reaction with OH,O3,and the first order rate constants of eight species of high molecular weight PAHs(i.e.B[a]A,Chry,B[b]F,B[k]F,B[a]P,Ind,B[g,h,i]P and Ret)as a function of humidity,solar intensity and temperature by using Multiple Regression Analysis.The predicted atmospheric lifetime of Ac,Ace,Ph,MePh3,MePh9,MePh2 and MePh1 ranged between 11.42 h-79.12 h in cold period and 1/31 h-14.33 h in warm period respectively.The binary ratios of atmospheric lifetime of B[k]F/B[g,h,i]P,B[k]F/B[g,h,i]P,B[g,h,i]P/Ind and B[k]F/Ind displayed non-significant differences between cold and warm period,indicating that high molecular weight PAHs are difficult to be decomposed by UV light and thus may be conveyed to the rural regions via long range atmospheric transportation(LRAT).The decreased level of the atmospheric lifetime of low molecular weight PAHs in summer can be attributed to an increased level of OH radical content and solar radiation.展开更多
露天矿无人矿车在装卸载作业区内运输过程中的长时间停车等待是制约露天矿无人运输系统效率提升的瓶颈。为提高无人矿车的运输效率,本文结合作业区内的运输作业流程,提出一种基于动态可行驶距离的多车协同通行决策方法。首先,将决策模...露天矿无人矿车在装卸载作业区内运输过程中的长时间停车等待是制约露天矿无人运输系统效率提升的瓶颈。为提高无人矿车的运输效率,本文结合作业区内的运输作业流程,提出一种基于动态可行驶距离的多车协同通行决策方法。首先,将决策模型建模为混合整数线性规划(Mixed Integer Linear Programming, MILP)模型,表述优化目标和问题约束;其次,考虑到求解MILP模型存在难以满足动态决策实时性的问题,基于蒙特卡洛树搜索(Monte Carlo Tree Search,MCTS)实现多车冲突消解,核心思想是利用搜索树的推演能力进行多车通行前瞻模拟,计算多车的最优通行优先级,动态调整多车的可行驶距离;此外,根据无人矿车在作业区内的作业特征设计不同的MCTS节点价值函数,实现综合考虑运输效率与作业特征的通行优先级排序;最后,设计作业区4,8,12个停车位场景下的多车通行仿真实验,与基于先到先服务(First-Come-FirstServed, FCFS)的方法进行对比,吞吐量提升22.03%~28.00%,平均停车等待时间缩短31.71%~50.79%。同时,搭建微缩智能车辆的6停车位作业区场景实验平台,多车单次运输作业总用时相比FCFS缩短了18.84%。仿真与微缩智能车辆的实验结果表明,本文提出的方法能够提升露天矿作业区多车运输效率。展开更多
基金National Natural Science Foundation of China(No.51278094)the Innovation Foundation of Shanghai Education Commission,China(No.13ZZ054)
文摘To overcome the disadvantages of displacement ventilation( DV) and traditional mixing ventilation( MV) system,a new ventilation system known as impinging jet ventilation system( IJVS)has been developing. The warm air can be supplied with impinging jet ventilation( IJV), while the DV is only used for cooling.However,the flow and temperature field of IJV under heating scenario has had few references. The paper is mainly focused on computational fluid dynamics( CFD) and developing an adequate correlation between the distance L that warm air can reach and different parameters in the warm IJVS by using response surface methodology( RSM). The results indicate that L decreases as the supply velocity υ decreases but increases as the supply temperature difference ΔT or the discharge height h decreases. In the variable air volume( VAV) system, it is necessary to determine supply parameters both under the maximum-heat-load condition and the small-heat-load condition. Unlike the VAV system,the constant air volume( CAV) system has no need to study the small-heat-load condition. Draught discomfort near the nozzle becomes the issue of concern in IJVS, thus the suitable discharge height is of great importance in design and can be calculated based on the predictive model.
基金Major Program of the National Natural Science Foundation of China(41290255)National Natural Science Foundation of China(41305082)Fundamental Research Funds of Chengdu Institute of Plateau Meteorology,CMA
文摘This paper attempts to reveal a long-distance-relayed water vapor transport(LRWVT) east of Tibetan Plateau and its impacts. The results show that from August to October, east of Tibetan Plateau, there exists a unique LRWVT,and the water vapor from the South China Sea and the western Pacific can affect the Sichuan Basin, Northwest China and other Chinese regions far from the tropical sea through this way. From August to October, the precipitation of the region east of the Plateau is closely linked both in the intra-annual and inter-annual variations, and the LRWVT from the South China Sea and the western Pacific is an important connection mechanism. The large-scale circulation background of the LRWVT impacting the precipitation of the region east of the Plateau is as follows: At high levels,the South Asian High is generally stronger than normal and significantly enhances with its northward advance and eastward extension over the region east of the Plateau. At mid-level, a broad low pressure trough is over Lake Balkhash and its surroundings, and the Western Pacific Subtropical High(WPSH) is northward and westward located, and the western part of Sichuan Basin and the eastern part of Northwest China are located in the west and northwest edge of WPSH.
文摘Connes' distance formula is applied to endow linear metric to three 1D lattices of different topologies with a generalization of lattice Dirac operator written down by Dimakis et al.to contain a non-unitary link-variable.Geometric interpretation of this link-variable is lattice spacing and parallel transport.
文摘Atmospheric lifetimes and traveling distances of 15 PAHs(Ac:acenaphthylene,Ace:acenaphthene,Ph:phenanthrene,MePh3:3-methyl-phenanthrene,MePh9:9-methyl-phenanthrene,MePh1:1-methyl-phenanthrene,MePh2:2-methyl-phenanthrene,Ret:retene,B[a]A:benzo[a]anthracene,Chry:chrysene,B[b,j,k]F:benzo[b,j,k]fluoranthene,B[e]P:benzo[e]pyrene,B[a]P:benzo[a]pyrene,Ind:indeno[1,2,3-cd]pyrene,B[g,h,i]P:benzo[g,h,i]perylene)at Whitbourne,UK,were estimated by using the rate constants for reaction with OH,O3,and the first order rate constants of eight species of high molecular weight PAHs(i.e.B[a]A,Chry,B[b]F,B[k]F,B[a]P,Ind,B[g,h,i]P and Ret)as a function of humidity,solar intensity and temperature by using Multiple Regression Analysis.The predicted atmospheric lifetime of Ac,Ace,Ph,MePh3,MePh9,MePh2 and MePh1 ranged between 11.42 h-79.12 h in cold period and 1/31 h-14.33 h in warm period respectively.The binary ratios of atmospheric lifetime of B[k]F/B[g,h,i]P,B[k]F/B[g,h,i]P,B[g,h,i]P/Ind and B[k]F/Ind displayed non-significant differences between cold and warm period,indicating that high molecular weight PAHs are difficult to be decomposed by UV light and thus may be conveyed to the rural regions via long range atmospheric transportation(LRAT).The decreased level of the atmospheric lifetime of low molecular weight PAHs in summer can be attributed to an increased level of OH radical content and solar radiation.
文摘露天矿无人矿车在装卸载作业区内运输过程中的长时间停车等待是制约露天矿无人运输系统效率提升的瓶颈。为提高无人矿车的运输效率,本文结合作业区内的运输作业流程,提出一种基于动态可行驶距离的多车协同通行决策方法。首先,将决策模型建模为混合整数线性规划(Mixed Integer Linear Programming, MILP)模型,表述优化目标和问题约束;其次,考虑到求解MILP模型存在难以满足动态决策实时性的问题,基于蒙特卡洛树搜索(Monte Carlo Tree Search,MCTS)实现多车冲突消解,核心思想是利用搜索树的推演能力进行多车通行前瞻模拟,计算多车的最优通行优先级,动态调整多车的可行驶距离;此外,根据无人矿车在作业区内的作业特征设计不同的MCTS节点价值函数,实现综合考虑运输效率与作业特征的通行优先级排序;最后,设计作业区4,8,12个停车位场景下的多车通行仿真实验,与基于先到先服务(First-Come-FirstServed, FCFS)的方法进行对比,吞吐量提升22.03%~28.00%,平均停车等待时间缩短31.71%~50.79%。同时,搭建微缩智能车辆的6停车位作业区场景实验平台,多车单次运输作业总用时相比FCFS缩短了18.84%。仿真与微缩智能车辆的实验结果表明,本文提出的方法能够提升露天矿作业区多车运输效率。