Improved understanding of the effect of shrub cover on soil erosion process will provide valuable information for soil and water conservation programs.Laboratory rainfall simulations were conducted to determine the ef...Improved understanding of the effect of shrub cover on soil erosion process will provide valuable information for soil and water conservation programs.Laboratory rainfall simulations were conducted to determine the effects of shrubs on runoff and soil erosion and to ascertain the relationship between the rate of soil loss and the runoff hydrodynamic characteristics.In these simulations a 20° slope was subjected to rainfall intensities of 45,87,and 127 mm/h.The average runoff rates ranged from 0.51 to 1.26 mm/min for bare soil plots and 0.15 to 0.96 mm/min for shrub plots.Average soil loss rates varied from 44.19 to 114.61 g/(min·m^2) for bare soil plots and from 5.61 to 84.58 g/(min·m^2) for shrub plots.There was a positive correlation between runoff and soil loss for the bare soil plots,and soil loss increased with increased runoff for shrub plots only when rainfall intensity is 127 mm/h.Runoff and soil erosion processes were strongly influenced by soil surface conditions because of the formation of erosion pits and rills.The unit stream power was the optimal hydrodynamic parameter to characterize the soil erosion mechanisms.The soil loss rate increased linearly with the unit stream power on both shrub and bare soil plots.Critical unit stream power values were 0.004 m/s for bare soil plots and 0.017 m/s for shrub plots.展开更多
The numerical simulation of jet flow field in Laval tube was carried out first by commercial software CFX4.4, and it is used to determine inlet pressure condition out of nozzle in order to its numerical simulation. Th...The numerical simulation of jet flow field in Laval tube was carried out first by commercial software CFX4.4, and it is used to determine inlet pressure condition out of nozzle in order to its numerical simulation. The decay rule of jet middle line velocity of axial symmetry turbulence jet and cross section＇s expand situation out of the tube in different stagnation pressure and surrounding temperature were analyzed systematically. The result showed that K-e model is suitable for numerical simulation. The conclusion will have important guide and referent function to research of two important craft parameters, impact depth and the impact area which are related to steel-making production practice.展开更多
This paper is devoted to development and study of models for operator training systems of heating power station processes management. It proposed a mathematical model describing the management processes of heating pow...This paper is devoted to development and study of models for operator training systems of heating power station processes management. It proposed a mathematical model describing the management processes of heating power units of the technological complex considering the relationship of technological variables in deviations effective in real time. A software complex is developed for the system of training of operators controlling processes in heating station units. Obtained results may be used in the course of development of computer training systems for operators of heating power stations with cross-linkage.展开更多
A series of conjugated copolymers of 9,9-dioctylfluorene and symmetrical pyrazine unit (BY) were synthesized by Suzuki copolymerization and were used as novel light-emitting materials in PLEDs.Efficient energy transfe...A series of conjugated copolymers of 9,9-dioctylfluorene and symmetrical pyrazine unit (BY) were synthesized by Suzuki copolymerization and were used as novel light-emitting materials in PLEDs.Efficient energy transfer was observed in both thin film and solution.Compared with the lowest occupied molecular orbital (LUMO) energy level of the polyfluorenes homopolymer (PFO),the lower LUMO energy levels of copolymers indicated that the introduction of the BY unit would be benefit to electron injection.The turn-on voltages of their single-layer electroluminescent (EL) devices (ITO/PEDOT/polymer/LiF/Al) were at 6.1-4.0 V,which were much lower than that of PFO (7.0 V).The maximum brightness,current efficiency,and external quantum efficiency of all PFBY copolymers were higher than those of the PFO homopolymer.The single-layer device of PFBY5 was the best one in the copolymers,with a maximum brightness of 485 cd/m2,a current efficiency of 0.29 cd/A,and an external quantum efficiency of 0.10%.The introduction of PVK and TPBI for the multilayer device of PFBY5 increased the device efficiencies,which showed a maximum brightness of 3012 cd/m2,a maximum current efficiency of 1.81 cd/A,and an external quantum efficiency of 0.66%.展开更多
基金Under the auspices of National Basic Research Program of China(No.2011CB403303)National Natural Science Foundation of China(No.41571276)+1 种基金Innovation Scientists and Technicians Troop Construction Projects of Henan Province(No.162101510004)Foundation of Yellow River Institute of Hydraulic Research of China(No.HKY-JBYW-2016-33)
文摘Improved understanding of the effect of shrub cover on soil erosion process will provide valuable information for soil and water conservation programs.Laboratory rainfall simulations were conducted to determine the effects of shrubs on runoff and soil erosion and to ascertain the relationship between the rate of soil loss and the runoff hydrodynamic characteristics.In these simulations a 20° slope was subjected to rainfall intensities of 45,87,and 127 mm/h.The average runoff rates ranged from 0.51 to 1.26 mm/min for bare soil plots and 0.15 to 0.96 mm/min for shrub plots.Average soil loss rates varied from 44.19 to 114.61 g/(min·m^2) for bare soil plots and from 5.61 to 84.58 g/(min·m^2) for shrub plots.There was a positive correlation between runoff and soil loss for the bare soil plots,and soil loss increased with increased runoff for shrub plots only when rainfall intensity is 127 mm/h.Runoff and soil erosion processes were strongly influenced by soil surface conditions because of the formation of erosion pits and rills.The unit stream power was the optimal hydrodynamic parameter to characterize the soil erosion mechanisms.The soil loss rate increased linearly with the unit stream power on both shrub and bare soil plots.Critical unit stream power values were 0.004 m/s for bare soil plots and 0.017 m/s for shrub plots.
文摘The numerical simulation of jet flow field in Laval tube was carried out first by commercial software CFX4.4, and it is used to determine inlet pressure condition out of nozzle in order to its numerical simulation. The decay rule of jet middle line velocity of axial symmetry turbulence jet and cross section＇s expand situation out of the tube in different stagnation pressure and surrounding temperature were analyzed systematically. The result showed that K-e model is suitable for numerical simulation. The conclusion will have important guide and referent function to research of two important craft parameters, impact depth and the impact area which are related to steel-making production practice.
文摘This paper is devoted to development and study of models for operator training systems of heating power station processes management. It proposed a mathematical model describing the management processes of heating power units of the technological complex considering the relationship of technological variables in deviations effective in real time. A software complex is developed for the system of training of operators controlling processes in heating station units. Obtained results may be used in the course of development of computer training systems for operators of heating power stations with cross-linkage.
基金supported by the National Natural Science Foundation of China (50803062,60977026 & 20904055)the Science Fund for Creative Research Groups (20621401)the Natural Basic Research Foundation of China (973 Program,2009CB623601)
文摘A series of conjugated copolymers of 9,9-dioctylfluorene and symmetrical pyrazine unit (BY) were synthesized by Suzuki copolymerization and were used as novel light-emitting materials in PLEDs.Efficient energy transfer was observed in both thin film and solution.Compared with the lowest occupied molecular orbital (LUMO) energy level of the polyfluorenes homopolymer (PFO),the lower LUMO energy levels of copolymers indicated that the introduction of the BY unit would be benefit to electron injection.The turn-on voltages of their single-layer electroluminescent (EL) devices (ITO/PEDOT/polymer/LiF/Al) were at 6.1-4.0 V,which were much lower than that of PFO (7.0 V).The maximum brightness,current efficiency,and external quantum efficiency of all PFBY copolymers were higher than those of the PFO homopolymer.The single-layer device of PFBY5 was the best one in the copolymers,with a maximum brightness of 485 cd/m2,a current efficiency of 0.29 cd/A,and an external quantum efficiency of 0.10%.The introduction of PVK and TPBI for the multilayer device of PFBY5 increased the device efficiencies,which showed a maximum brightness of 3012 cd/m2,a maximum current efficiency of 1.81 cd/A,and an external quantum efficiency of 0.66%.
