本文通过分析我国目前的医学教育现状、以案例为基础的学习方法(case based learning,CBL)与以问题为中心的学习方法(problem based learning,PBL)的特点,探讨CBL联合PBL教学法在我国医学教育中的可行性,以期为医学教育工作者提供新的...本文通过分析我国目前的医学教育现状、以案例为基础的学习方法(case based learning,CBL)与以问题为中心的学习方法(problem based learning,PBL)的特点,探讨CBL联合PBL教学法在我国医学教育中的可行性,以期为医学教育工作者提供新的思路。展开更多
A numerical model is developed by coupling the cellular automaton(CA)method and the lattice Boltzmann method(LBM)to simulate the dendritic growth of Al-Cu alloy in both two and three dimensions.An improved decentered ...A numerical model is developed by coupling the cellular automaton(CA)method and the lattice Boltzmann method(LBM)to simulate the dendritic growth of Al-Cu alloy in both two and three dimensions.An improved decentered square algorithm is proposed to overcome the artificial anisotropy induced by the CA cells and to realize simulation of dendritic growth with arbitrary orientations.Based on the established CA-LBM model,effects of forced convection and gravity-driven natural convection on dendritic growth are studied.The simulation results show that the blocking effect of dendrites on melt flow is advanced with a larger number of seeds.The competitive growth of the converging columnar dendrites is determined by the interaction between heat flow and forced convection.Gravity-driven natural convection leads to highly asymmetric growth of equiaxed dendrites.With sinking downwards of the heavy solute,chimney-like or mushroom-like solute plumes are formed in the melt in front of the columnar dendrites when they grow along the gravitational direction.More details on dendritic growth of Al-Cu alloy under convection are revealed by 3D simulations.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.51805389)the Key R&D Program of Hubei Province,China(Grant No.2021BAA048)+1 种基金the 111 Project(Grant No.B17034)the fund of Hubei Key Laboratory of Advanced Technology for Automotive Components,Wuhan University of Technology(Grant No.XDQCKF2021011).
文摘A numerical model is developed by coupling the cellular automaton(CA)method and the lattice Boltzmann method(LBM)to simulate the dendritic growth of Al-Cu alloy in both two and three dimensions.An improved decentered square algorithm is proposed to overcome the artificial anisotropy induced by the CA cells and to realize simulation of dendritic growth with arbitrary orientations.Based on the established CA-LBM model,effects of forced convection and gravity-driven natural convection on dendritic growth are studied.The simulation results show that the blocking effect of dendrites on melt flow is advanced with a larger number of seeds.The competitive growth of the converging columnar dendrites is determined by the interaction between heat flow and forced convection.Gravity-driven natural convection leads to highly asymmetric growth of equiaxed dendrites.With sinking downwards of the heavy solute,chimney-like or mushroom-like solute plumes are formed in the melt in front of the columnar dendrites when they grow along the gravitational direction.More details on dendritic growth of Al-Cu alloy under convection are revealed by 3D simulations.
