The general principle of utilizing the BGK equation to simulate a macroscopic gas flow is illustrated. Two typical examples, i.e., a low-speed axisymmetric submerged jet and the Prandtl-Meyer expansion to a vacuum, ar...The general principle of utilizing the BGK equation to simulate a macroscopic gas flow is illustrated. Two typical examples, i.e., a low-speed axisymmetric submerged jet and the Prandtl-Meyer expansion to a vacuum, are presented for validating the feasibility and accuracy of the BGK-equation simulation in continuum and non-continuum flow regimes. This approach is then used to simulate the exhaust plume formed by a small manoeuvre thruster of an artificial satellite in the outer space. The plume impingement on a flat surface perpendicular to the nozzle axis is also simulated by the same method. In the latter case the impingement force acting on the flat surface is calculated. When the flow reaches to the steady state the calculated impingement force is reasonably compared with the theoretical value of the nozzle thrust.展开更多
GaAs single crystal has been grown in recoverable satellite. Hall measurements indicate that the GaAs shows semi-insulating behavior. The structural properties of the crystal have been improved obviously, and their un...GaAs single crystal has been grown in recoverable satellite. Hall measurements indicate that the GaAs shows semi-insulating behavior. The structural properties of the crystal have been improved obviously, and their uniformity has been improved as well. The stoichiometry and its distribution in space-grown GaAs are improved greatly compared with the GaAs single crystal gmwn terrestrially. The properties of integrated circuits made by direct ion-implantation on space-grown GaAs are better than ihose made on gmund-gnmm materials. These results show that the stoichiometry in semi-insulating GaAs seriously affects the properties of related devices.展开更多
We identify the functions whose polynomial multiples are weak＊ dense in Qp spaces and prove that if ｜f（z）｜ ≥ ｜g（z）｜ and g is cyclic in Qp, then f is cyclic in Qp. We also show that the multiplication operato...We identify the functions whose polynomial multiples are weak＊ dense in Qp spaces and prove that if ｜f（z）｜ ≥ ｜g（z）｜ and g is cyclic in Qp, then f is cyclic in Qp. We also show that the multiplication operator Mx on Qp spaces is cellular indecomposable.展开更多
Let （Φ,Ψ） be a pair of complementary N-functions and HΦ（A） and HΨ（A） be the associated noncommutative Orlicz-Hardy spaces. We extend the Riesz, Szeg＆#168;o and inner-outer type factorization theorems of Hp...Let （Φ,Ψ） be a pair of complementary N-functions and HΦ（A） and HΨ（A） be the associated noncommutative Orlicz-Hardy spaces. We extend the Riesz, Szeg＆#168;o and inner-outer type factorization theorems of Hp（A） to this case.展开更多
基金The project supported by Beijing Institute of Spacecraft Overall Design
文摘The general principle of utilizing the BGK equation to simulate a macroscopic gas flow is illustrated. Two typical examples, i.e., a low-speed axisymmetric submerged jet and the Prandtl-Meyer expansion to a vacuum, are presented for validating the feasibility and accuracy of the BGK-equation simulation in continuum and non-continuum flow regimes. This approach is then used to simulate the exhaust plume formed by a small manoeuvre thruster of an artificial satellite in the outer space. The plume impingement on a flat surface perpendicular to the nozzle axis is also simulated by the same method. In the latter case the impingement force acting on the flat surface is calculated. When the flow reaches to the steady state the calculated impingement force is reasonably compared with the theoretical value of the nozzle thrust.
文摘GaAs single crystal has been grown in recoverable satellite. Hall measurements indicate that the GaAs shows semi-insulating behavior. The structural properties of the crystal have been improved obviously, and their uniformity has been improved as well. The stoichiometry and its distribution in space-grown GaAs are improved greatly compared with the GaAs single crystal gmwn terrestrially. The properties of integrated circuits made by direct ion-implantation on space-grown GaAs are better than ihose made on gmund-gnmm materials. These results show that the stoichiometry in semi-insulating GaAs seriously affects the properties of related devices.
基金supported by NNSF of China (10771130)Specialized Research Fund for the Doctoral Program of High Education (2007056004)+1 种基金NSF of GuangdongProvince (10151503101000025)NSF of Fujian Province (2009J01004)
文摘We identify the functions whose polynomial multiples are weak＊ dense in Qp spaces and prove that if ｜f（z）｜ ≥ ｜g（z）｜ and g is cyclic in Qp, then f is cyclic in Qp. We also show that the multiplication operator Mx on Qp spaces is cellular indecomposable.
文摘Let （Φ,Ψ） be a pair of complementary N-functions and HΦ（A） and HΨ（A） be the associated noncommutative Orlicz-Hardy spaces. We extend the Riesz, Szeg＆#168;o and inner-outer type factorization theorems of Hp（A） to this case.
