The flow and heat transfer of molten GaAs during Czochralski growth are studied with a time-dependent and three- dimensional turbulent flow model. A transition from axisymmetric flow to nonoaxisymmetric flow and then ...The flow and heat transfer of molten GaAs during Czochralski growth are studied with a time-dependent and three- dimensional turbulent flow model. A transition from axisymmetric flow to nonoaxisymmetric flow and then back to axisymmetric flow again with increasing the crucible rotation rate is predicted. In the non-axisymmetric regime, the thermal wave induced by the combination of coriolis force, buoyancy and viscous force in the GaAs melt is predicted for the first time. The thermal wave is confirmed to be baroclinic thermal wave. The origin of the transition to non-axisymmetric flow is baroclinic instability. The critical parameters for the, transitions are presented, which are quantitatively in agreement with Fein and Preffer＇s experimental results, The calculated results can be taken as a reference for the growth of GaAs single-crystal of high quality,展开更多
A regular edge-transitive graph is said to be semisymmetric if it is mot vertex-transitive. By Folkman [J. Combin. Theory 3 （1967）, 215-232], there is no semisymmetric graph of order 2p or 2p^2 for a prime p, and by...A regular edge-transitive graph is said to be semisymmetric if it is mot vertex-transitive. By Folkman [J. Combin. Theory 3 （1967）, 215-232], there is no semisymmetric graph of order 2p or 2p^2 for a prime p, and by Malni6 et al. [Discrete Math. 274 （2004）, 18-198], there exists a unique cubic semisymmetrie graph of order 2p3, the so called Gray graph of order 54. In this paper, it is shown that there is no connected cubic semisymmetric graph of order 4p^3 and that there exists a unique cubic semisymmetric graph of order 8p3, which is a Z2 × Z2-covering of the Gray graph.展开更多
This paper deals with the peristaltic flow of an incompressible and electrically conducting Williamson fluid in a symmetric planar channel with heat and mass transfer. Hall effects, viscous dissipation and Joule heati...This paper deals with the peristaltic flow of an incompressible and electrically conducting Williamson fluid in a symmetric planar channel with heat and mass transfer. Hall effects, viscous dissipation and Joule heating are also taken into consideration. Mathematical model is presented by using the long wavelength and low Reynolds number approximations. The differential equations governing the flow are highly nonlinear and thus perturbation solution for small Weissenberg number （0 〈 We 〈 1） is presented. Effects of the heat and mass transfer Biot numbers and Hall parameter on the longitudinal velocity, temperature, concentration and pumping characteristics are studied in detail. Main observations are presented in the concluding section, The streamlines pattern and trapping are also given due attention.展开更多
基金Supported by the Natural Science Foundation of China (No 50376078).
文摘The flow and heat transfer of molten GaAs during Czochralski growth are studied with a time-dependent and three- dimensional turbulent flow model. A transition from axisymmetric flow to nonoaxisymmetric flow and then back to axisymmetric flow again with increasing the crucible rotation rate is predicted. In the non-axisymmetric regime, the thermal wave induced by the combination of coriolis force, buoyancy and viscous force in the GaAs melt is predicted for the first time. The thermal wave is confirmed to be baroclinic thermal wave. The origin of the transition to non-axisymmetric flow is baroclinic instability. The critical parameters for the, transitions are presented, which are quantitatively in agreement with Fein and Preffer＇s experimental results, The calculated results can be taken as a reference for the growth of GaAs single-crystal of high quality,
基金supported by National Natural Science Foundation of China (Grant No.10871021)the Specialized Research Fund for the Doctoral Program of Higher Education in China (Grant No.20060004026)
文摘A regular edge-transitive graph is said to be semisymmetric if it is mot vertex-transitive. By Folkman [J. Combin. Theory 3 （1967）, 215-232], there is no semisymmetric graph of order 2p or 2p^2 for a prime p, and by Malni6 et al. [Discrete Math. 274 （2004）, 18-198], there exists a unique cubic semisymmetrie graph of order 2p3, the so called Gray graph of order 54. In this paper, it is shown that there is no connected cubic semisymmetric graph of order 4p^3 and that there exists a unique cubic semisymmetric graph of order 8p3, which is a Z2 × Z2-covering of the Gray graph.
文摘This paper deals with the peristaltic flow of an incompressible and electrically conducting Williamson fluid in a symmetric planar channel with heat and mass transfer. Hall effects, viscous dissipation and Joule heating are also taken into consideration. Mathematical model is presented by using the long wavelength and low Reynolds number approximations. The differential equations governing the flow are highly nonlinear and thus perturbation solution for small Weissenberg number （0 〈 We 〈 1） is presented. Effects of the heat and mass transfer Biot numbers and Hall parameter on the longitudinal velocity, temperature, concentration and pumping characteristics are studied in detail. Main observations are presented in the concluding section, The streamlines pattern and trapping are also given due attention.
