In order to acquire the flow pattern and investigate the settling behavior of the red mud in the separation thickener,computational fluid dynamics(CFD),custom subroutines and agglomerates settling theory were employed...In order to acquire the flow pattern and investigate the settling behavior of the red mud in the separation thickener,computational fluid dynamics(CFD),custom subroutines and agglomerates settling theory were employed to simulate the three-dimensional flow field in an industrial scale thickener with the introduction of a self-dilute feed system.The simulation results show good agreement with the measurement onsite and the flow patterns of the thickener are presented and discussed on both velocity and concentration field.Optimization experiments on feed well and self-dilute system were also carried out,and indicate that the optimal thickener system can dilute the solid concentration in feed well from 110 g/L to 86 g/L which would help the agglomerates' formation and improve the red mud settling speed.Furthermore,the additional power of recirculation pump can be saved and flocculants dosage was reduced from 105g/t to 85g/t in the operation.展开更多
Bulk polymerizations of styrene (St) were carried out in the presence of three reversible addition fragmentation chain transfer (RAFT) agents benzyl dithiobenzoate (BDB), cumyl dithiobenzoate(CDB), and 1-phenylethyl d...Bulk polymerizations of styrene (St) were carried out in the presence of three reversible addition fragmentation chain transfer (RAFT) agents benzyl dithiobenzoate (BDB), cumyl dithiobenzoate(CDB), and 1-phenylethyl dithiobenzoate (PEDB) under low ratio of RAFT agent to initiator. The kinetic model was developed to predict polymerization rate, which indicates that the RAFT polymerization of St is a first-order reaction. In the range of experimental conversions, the plots of -ln(1-x) against time t are approximately linear (x is monomer conversion). The kinetic study reveals the existence of strong rate retardation in RAFT polymerization of styrene. A coefficient K_r is defined to estimate the rate retardation in the RAFT system considering the assumption that the retardation in polymerization rate is mainly attributed to slow fragmentation of the intermediate radicals. K_r relates to the structure of RAFT agents as well as the concentrations of RAFT agent and azobis isobutyronitrile (AIBN). For a certain RAFT agent, the value of K_r is enhanced by the increase in the initial concentration of RAFT agent and the higher ratio of RAFT to AIBN. With the same recipe for different RAFT agents, the increasing trend for the values of K_r is BDB<PEDB<CDB.展开更多
A series of experiments on a solid feed system was performed to investigate the effect of negative pressure gradient on the gas-solid flow pattern and hydrodynamic characteristics.Based on the non-fluidized gas-solid ...A series of experiments on a solid feed system was performed to investigate the effect of negative pressure gradient on the gas-solid flow pattern and hydrodynamic characteristics.Based on the non-fluidized gas-solid two phase flow and particulate mechanics in the standpipe,a method for predicting the pressure of the air passing through the recycle chamber and the pressure drop through the loop seal slit in these systems is also presented.The predicted pressure profile along the negative pressure gradient from the proposed model exhibits a good agreement with the experimental data.The experimental data show that the gas flow in the standpipe is always upward in the negative pressure gradients,while the direction ofthe superficial gas velocity through the recycle chamber of the loop seal does not affect the pressure drop in standpipe.It increases with an increasing negative pressure gradient.展开更多
A nested-model system is constructed by embedding the regional climate model RegCM3 into a general circulation model for monthly-scale regional climate forecast over East China. The systematic errors are formulated fo...A nested-model system is constructed by embedding the regional climate model RegCM3 into a general circulation model for monthly-scale regional climate forecast over East China. The systematic errors are formulated for the region on the basis of 10-yr (1991-2000) results of the nested-model system, and of the datasets of the Climate Prediction Center (CPC) Merged Analysis of Precipitation (CMAP) and the temperature analysis of the National Meteorological Center (NMC), U.S.A., which are then used for correcting the original forecast by the system for the period 2001-2005. After the assessment of the original and corrected forecasts for monthly precipitation and surface air temperature, it is found that the corrected forecast is apparently better than the original, suggesting that the approach can be applied for improving monthly-scale regional climate dynamical forecast.展开更多
Using Langevin simulations, we study numerically the directional mode-locking of the dynamics of two- dimensional superpararnagnetic colloidal system in a periodic pinning array. When the colloidal particles are initi...Using Langevin simulations, we study numerically the directional mode-locking of the dynamics of two- dimensional superpararnagnetic colloidal system in a periodic pinning array. When the colloidal particles are initially commensurate with the pinning sites, there appear mode-locking steps in the average velocity of colloidal particles along certain directions of the external driving force. With an increase in the pinning strength, the width of the step increases linearly but the velocity at the step decreases parabolically.展开更多
Energy flow drives the complex systems to evolve.The allometric scaling as the universalenergy flow pattern has been found in different scales of ecological systems.It reflects the generalpower law relationship betwee...Energy flow drives the complex systems to evolve.The allometric scaling as the universalenergy flow pattern has been found in different scales of ecological systems.It reflects the generalpower law relationship between flow and store.The underlying mechanisms of energy flow patterns areexplained as the branching transportation networks which can be regarded as the result of systematicoptimization of a biological target under constraints.Energy flows in the ecological system may bemodelled by the food web model and population dynamics on the network.This paper reviews thelatest progress on the energy flow patterns,explanatory models for the allometric scaling and modellingapproach of flow and network evolution dynamics in ecology.Furthermore,the possibility of generalizingthese flow patterns,modelling approaches to other complex systems is discussed.展开更多
In this paper, a nonlinear mathematical model is presented for the transmission dynamics of HIV/AIDS in Cuba. Due to Cuba＇s highly successful national prevention program, we assume that the only mode of transmission ...In this paper, a nonlinear mathematical model is presented for the transmission dynamics of HIV/AIDS in Cuba. Due to Cuba＇s highly successful national prevention program, we assume that the only mode of transmission is through contact with those yet to be diagnosed with HIV. We find the equilibria of the governing nonlinear system, perform a linear stability analysis, and then provide results on global stability.展开更多
基金Project(50876116)supported by the National Natural Science Foundation of China
文摘In order to acquire the flow pattern and investigate the settling behavior of the red mud in the separation thickener,computational fluid dynamics(CFD),custom subroutines and agglomerates settling theory were employed to simulate the three-dimensional flow field in an industrial scale thickener with the introduction of a self-dilute feed system.The simulation results show good agreement with the measurement onsite and the flow patterns of the thickener are presented and discussed on both velocity and concentration field.Optimization experiments on feed well and self-dilute system were also carried out,and indicate that the optimal thickener system can dilute the solid concentration in feed well from 110 g/L to 86 g/L which would help the agglomerates' formation and improve the red mud settling speed.Furthermore,the additional power of recirculation pump can be saved and flocculants dosage was reduced from 105g/t to 85g/t in the operation.
文摘Bulk polymerizations of styrene (St) were carried out in the presence of three reversible addition fragmentation chain transfer (RAFT) agents benzyl dithiobenzoate (BDB), cumyl dithiobenzoate(CDB), and 1-phenylethyl dithiobenzoate (PEDB) under low ratio of RAFT agent to initiator. The kinetic model was developed to predict polymerization rate, which indicates that the RAFT polymerization of St is a first-order reaction. In the range of experimental conversions, the plots of -ln(1-x) against time t are approximately linear (x is monomer conversion). The kinetic study reveals the existence of strong rate retardation in RAFT polymerization of styrene. A coefficient K_r is defined to estimate the rate retardation in the RAFT system considering the assumption that the retardation in polymerization rate is mainly attributed to slow fragmentation of the intermediate radicals. K_r relates to the structure of RAFT agents as well as the concentrations of RAFT agent and azobis isobutyronitrile (AIBN). For a certain RAFT agent, the value of K_r is enhanced by the increase in the initial concentration of RAFT agent and the higher ratio of RAFT to AIBN. With the same recipe for different RAFT agents, the increasing trend for the values of K_r is BDB<PEDB<CDB.
文摘A series of experiments on a solid feed system was performed to investigate the effect of negative pressure gradient on the gas-solid flow pattern and hydrodynamic characteristics.Based on the non-fluidized gas-solid two phase flow and particulate mechanics in the standpipe,a method for predicting the pressure of the air passing through the recycle chamber and the pressure drop through the loop seal slit in these systems is also presented.The predicted pressure profile along the negative pressure gradient from the proposed model exhibits a good agreement with the experimental data.The experimental data show that the gas flow in the standpipe is always upward in the negative pressure gradients,while the direction ofthe superficial gas velocity through the recycle chamber of the loop seal does not affect the pressure drop in standpipe.It increases with an increasing negative pressure gradient.
基金National Natural Science Foundation of China (40875067, 40675040)Knowledge Innovation Program of the Chinese Academy of Sciences (IAP09306)National Basic Research Program of China. (2006CB400505)
文摘A nested-model system is constructed by embedding the regional climate model RegCM3 into a general circulation model for monthly-scale regional climate forecast over East China. The systematic errors are formulated for the region on the basis of 10-yr (1991-2000) results of the nested-model system, and of the datasets of the Climate Prediction Center (CPC) Merged Analysis of Precipitation (CMAP) and the temperature analysis of the National Meteorological Center (NMC), U.S.A., which are then used for correcting the original forecast by the system for the period 2001-2005. After the assessment of the original and corrected forecasts for monthly precipitation and surface air temperature, it is found that the corrected forecast is apparently better than the original, suggesting that the approach can be applied for improving monthly-scale regional climate dynamical forecast.
基金Supported by the Scientific Research Foundation of Graduate School of Zhengzhou Universitythe Natural Science Research Foundation of Henan Provincial Department of Science and Technology under Grant No. 112300410151
文摘Using Langevin simulations, we study numerically the directional mode-locking of the dynamics of two- dimensional superpararnagnetic colloidal system in a periodic pinning array. When the colloidal particles are initially commensurate with the pinning sites, there appear mode-locking steps in the average velocity of colloidal particles along certain directions of the external driving force. With an increase in the pinning strength, the width of the step increases linearly but the velocity at the step decreases parabolically.
基金supported by Guozhi Xu Post Doctoral Research Foundationthe National Natural Science Foundation of China under Grant No. 60574068.
文摘Energy flow drives the complex systems to evolve.The allometric scaling as the universalenergy flow pattern has been found in different scales of ecological systems.It reflects the generalpower law relationship between flow and store.The underlying mechanisms of energy flow patterns areexplained as the branching transportation networks which can be regarded as the result of systematicoptimization of a biological target under constraints.Energy flows in the ecological system may bemodelled by the food web model and population dynamics on the network.This paper reviews thelatest progress on the energy flow patterns,explanatory models for the allometric scaling and modellingapproach of flow and network evolution dynamics in ecology.Furthermore,the possibility of generalizingthese flow patterns,modelling approaches to other complex systems is discussed.
基金Acknowledgments The authors would like to thank organizers Rongsong Liu, Michael Dillon, and Duane Porter of the Rocky Mountain Mathematics Consortium held at the University of Wyoming in June 2012, which was supported by the National Science Foundation and the Institute for Mathematics and Its Applications.
文摘In this paper, a nonlinear mathematical model is presented for the transmission dynamics of HIV/AIDS in Cuba. Due to Cuba＇s highly successful national prevention program, we assume that the only mode of transmission is through contact with those yet to be diagnosed with HIV. We find the equilibria of the governing nonlinear system, perform a linear stability analysis, and then provide results on global stability.
