The leaching kinetics of low grade zinc oxide ore in NH3-NH4Cl-H2O system was studied. The effects of ore particle size, reaction temperature and the sum concentration of ammonium ion and ammonia on the leaching effic...The leaching kinetics of low grade zinc oxide ore in NH3-NH4Cl-H2O system was studied. The effects of ore particle size, reaction temperature and the sum concentration of ammonium ion and ammonia on the leaching efficiency of zinc were examined. The leaching kinetics of low-grade zinc oxide ore in NH3-NH4Cl-H2O system follows the kinetic law of shrinking-core model. The results show that diffusion through the inert particle pores is the leaching kinetics rate controlling step. The calculated apparent activation energy of the process is about 7.057 kJ/mol. The leaching efficiency of zinc is 92.1% under the conditions of ore particle size of 69 μm, holding at 80 ℃ for 60 min, sum ammonia concentration of 7.5 mol/L, the molar ratio of ammonium to ammonia being 2-1, and the ratio (g/mL) of solid to liquid being 1-10.展开更多
The aim of this study was to perform computational fluid dynamics (CFD) simulations on the airflows at the Hong Kong International Airport (HKIA). In particular, the effects of hangar buildings and terrain were studie...The aim of this study was to perform computational fluid dynamics (CFD) simulations on the airflows at the Hong Kong International Airport (HKIA). In particular, the effects of hangar buildings and terrain were studied to explore the effects of turbulence on flying aircraft, especially during landing. The CFD simulation showed that significant differences in wind speeds may occur between the north and the south runways on the western part of the HKIA under typhoon conditions with a strong north to northwesterly wind. Simulation also showed that the hanger buildings between the two runways on the western side and the nearby terrain could be causing the observed difference in the wind speeds. The results also indicated that these obstacles could cause significant wind speed variations at the western end of the south runway. This may affect the operation of landing aircraft. The CFD results for a typical typhoon case were analyzed and found to match the wind data recorded by an aircraft landing that day.展开更多
Based on the method to change blade loading type along blade height, that is, applying aft-loading at both end zones of cascade while applying fore-loading in the mid zone of cascade, HTC(Harbin Turbine Company) desig...Based on the method to change blade loading type along blade height, that is, applying aft-loading at both end zones of cascade while applying fore-loading in the mid zone of cascade, HTC(Harbin Turbine Company) designed a twisted and bowed stationary cascade with low aspect ratio and large enthalpy drop. To verify the aerodynamic performance of such cascade, firstly, low-speed wind tunnel tests were conducted to validate the calculation results of commercial software CFX, and then numerical simulations were made for the aerodynamic performance of the cascade at different Mach numbers. The simulation results show that the large enthalpy drop stationary cascade designed by HTC can offer good aerodynamic performance while keeping its high-load characteristics in the change range of outlet Mach number as stated in this paper.展开更多
This study analyzed the effects of ecological factors on secondary metabolites of Scutellaria baicalensis using two sources:92individual roots of S.baicalensis from all over China,and secondary metabolites,medicinal m...This study analyzed the effects of ecological factors on secondary metabolites of Scutellaria baicalensis using two sources:92individual roots of S.baicalensis from all over China,and secondary metabolites,medicinal materials and inorganic element contents obtained from the testing of 92 S.baicalensis rhizosphere soil samples.The study used environmental data from the Genuine Medicinal Material Spatial Analysis Database.Most of the chemical constituents of S.baicalensis were negatively correlated to latitude and positively correlated to temperature;generally,the contents of 21 chemical constituents were higher at low latitudes than that at high latitudes.By gradual regression analysis,it was found that the content of baicalin in S.baicalensis was negatively correlated to latitude and generally the content of inorganic elements in soil was excessively high(excluding Mg and Ca),which has a negative effect on the accumulation of chemical constituents in S.baicalensis.Based on the cluster analysis of 21 constituents,S.baicalensis from different places of origin was divided into two groups,and S.baicalensis was not genuine only in a specific small region.Within the zone from Chifeng,Inner Mongolia to Taibai,Shaanxi is suitable for accumulation of secondary metabolites of S.baicalensis and such a zone represents a suitable distribution and potential genuine producing area.展开更多
基金Project(2007CB613604) supported by the Major State Basic Research Development Program of ChinaProject(50674104) supported by the National Natural Science Foundation of ChinaProject(GJJ08279) supported by the Department of Education of Jiangxi Province
文摘The leaching kinetics of low grade zinc oxide ore in NH3-NH4Cl-H2O system was studied. The effects of ore particle size, reaction temperature and the sum concentration of ammonium ion and ammonia on the leaching efficiency of zinc were examined. The leaching kinetics of low-grade zinc oxide ore in NH3-NH4Cl-H2O system follows the kinetic law of shrinking-core model. The results show that diffusion through the inert particle pores is the leaching kinetics rate controlling step. The calculated apparent activation energy of the process is about 7.057 kJ/mol. The leaching efficiency of zinc is 92.1% under the conditions of ore particle size of 69 μm, holding at 80 ℃ for 60 min, sum ammonia concentration of 7.5 mol/L, the molar ratio of ammonium to ammonia being 2-1, and the ratio (g/mL) of solid to liquid being 1-10.
文摘The aim of this study was to perform computational fluid dynamics (CFD) simulations on the airflows at the Hong Kong International Airport (HKIA). In particular, the effects of hangar buildings and terrain were studied to explore the effects of turbulence on flying aircraft, especially during landing. The CFD simulation showed that significant differences in wind speeds may occur between the north and the south runways on the western part of the HKIA under typhoon conditions with a strong north to northwesterly wind. Simulation also showed that the hanger buildings between the two runways on the western side and the nearby terrain could be causing the observed difference in the wind speeds. The results also indicated that these obstacles could cause significant wind speed variations at the western end of the south runway. This may affect the operation of landing aircraft. The CFD results for a typical typhoon case were analyzed and found to match the wind data recorded by an aircraft landing that day.
文摘Based on the method to change blade loading type along blade height, that is, applying aft-loading at both end zones of cascade while applying fore-loading in the mid zone of cascade, HTC(Harbin Turbine Company) designed a twisted and bowed stationary cascade with low aspect ratio and large enthalpy drop. To verify the aerodynamic performance of such cascade, firstly, low-speed wind tunnel tests were conducted to validate the calculation results of commercial software CFX, and then numerical simulations were made for the aerodynamic performance of the cascade at different Mach numbers. The simulation results show that the large enthalpy drop stationary cascade designed by HTC can offer good aerodynamic performance while keeping its high-load characteristics in the change range of outlet Mach number as stated in this paper.
基金supported by the National Natural Science Foundation of China(81130070,81072989)the National Key Technology Research and Development Program of China(2012BAI29B02)
文摘This study analyzed the effects of ecological factors on secondary metabolites of Scutellaria baicalensis using two sources:92individual roots of S.baicalensis from all over China,and secondary metabolites,medicinal materials and inorganic element contents obtained from the testing of 92 S.baicalensis rhizosphere soil samples.The study used environmental data from the Genuine Medicinal Material Spatial Analysis Database.Most of the chemical constituents of S.baicalensis were negatively correlated to latitude and positively correlated to temperature;generally,the contents of 21 chemical constituents were higher at low latitudes than that at high latitudes.By gradual regression analysis,it was found that the content of baicalin in S.baicalensis was negatively correlated to latitude and generally the content of inorganic elements in soil was excessively high(excluding Mg and Ca),which has a negative effect on the accumulation of chemical constituents in S.baicalensis.Based on the cluster analysis of 21 constituents,S.baicalensis from different places of origin was divided into two groups,and S.baicalensis was not genuine only in a specific small region.Within the zone from Chifeng,Inner Mongolia to Taibai,Shaanxi is suitable for accumulation of secondary metabolites of S.baicalensis and such a zone represents a suitable distribution and potential genuine producing area.
