A two-dimensional（2-D） incompressible plane jet is investigated using the lattice Boltzmann method（LBM） for low Reynolds numbers of 42 and 65 based on the jet-exit-width and the maximum jet-exit-velocity. The resu...A two-dimensional（2-D） incompressible plane jet is investigated using the lattice Boltzmann method（LBM） for low Reynolds numbers of 42 and 65 based on the jet-exit-width and the maximum jet-exit-velocity. The results show that the mean centerline velocity decays as x-1/3 and the jet spreads as x2/3 in the self-similar region, which are consistent with the theoretical predictions and the experimental data. The time histories and PSD analyses of the instantaneous centerline velocities indicate the periodic behavior and the interaction between periodic components of velocities should not be neglected in the far field region, although it is invisible in the near field region.展开更多
A 2D square lattice is studied. By using the continuum approximation, we set up the differential equations of motion for an arbitrary particle in the square lattice which subjects to an external periodic substrate pot...A 2D square lattice is studied. By using the continuum approximation, we set up the differential equations of motion for an arbitrary particle in the square lattice which subjects to an external periodic substrate potential. The exact solitary waves of the system are found for special cases. We conclude that the adhesive force f and the angle between propagation directions of upper and lower layers can affect these waves.展开更多
In this paper we give a characterization of planar lattices, and show that the sublattice L C Zn corresponding to the Hibi ideal of a finite distributive lattice L has a nice lattice basis if and only if L is planar. ...In this paper we give a characterization of planar lattices, and show that the sublattice L C Zn corresponding to the Hibi ideal of a finite distributive lattice L has a nice lattice basis if and only if L is planar. We also consider the Grobner basis of the lattice basis ideal attached to the planar lattices.展开更多
The motion of micro-particles with different mass flow rate in the planer turbulent jet flow has been simulated, using LES method to obtain the flow vorticity evolution and Lagrangian method to track micro-particles. ...The motion of micro-particles with different mass flow rate in the planer turbulent jet flow has been simulated, using LES method to obtain the flow vorticity evolution and Lagrangian method to track micro-particles. The re- suits showed that when the flow rate is small, the particles more likely to present in the vortex periphery, the dis- tribution pattern is similar to the flow pattern. When the flow rate is high, some particles will escape from the mo- tion region to the original static region, so that in the jet region, particles are relatively evenly distributed. When the flow field is full developed, the particles average concentration in the y direction affected by the mass flow rate relative slightly, the normalized mean particles concentrations at different flow rate were similar to Gaussian shape.展开更多
文摘消防员问题 (Firefighter Problem) 是一个离散的动态传播模型,与疫情控制、谣言传播、森林防火等实际问题密切相关,它最早是由著名计算机理论学家 Hartnell 在 1995 年的第 25 届组合数学与计算大会上首次提出的。令 G = (V (G), E(G)) 是 n (n ≥ 2) 个顶点的连通图。假设火在图 G 中任意一个顶点 v 处燃起,消防员则选择未着火的顶点去保护(一旦某个顶点被保护,则在整个过程中都将处千被保护状态),然后火蔓延到 v 的未加保护且没着火的邻点。依次下去,火和消防员交替地在图 G 上移动, 直到火不能继续蔓延,整个过程结束,消防员的任务是使最后获救的点数最多。令 sn(v) 表示当图 G 中的顶点 v 作为火源点时一个消防员所能保护的最多顶点数。图 G 的存活率 ρ(G) 定义为 ,即当火随机地在图 G 的一个顶点燃起时,一个消防员最多能保护的顶点数的平均值。本文首先研究有限平面 4 ·82 格子图的存活率,分析格子图中点存活数的变化出有限 4 ·82 格子图的存活率的确切值;从而证明了对于无限平面 4 ·82 格子图, 每个回合使用一个消防员经过有限次保护后可以控制火的蔓延。
基金Supported by the National Nature Science Foundation of China(10472046)the Scientific Innova-tion Research of College Graduate in Jiangsu Province(CX08B-035Z)the Innovation and Excellence Foundation of Doctoral Dissertation of Nanjing University of Aeronautics and Astronautics(BCXJ08-01)~~
文摘A two-dimensional（2-D） incompressible plane jet is investigated using the lattice Boltzmann method（LBM） for low Reynolds numbers of 42 and 65 based on the jet-exit-width and the maximum jet-exit-velocity. The results show that the mean centerline velocity decays as x-1/3 and the jet spreads as x2/3 in the self-similar region, which are consistent with the theoretical predictions and the experimental data. The time histories and PSD analyses of the instantaneous centerline velocities indicate the periodic behavior and the interaction between periodic components of velocities should not be neglected in the far field region, although it is invisible in the near field region.
基金supported by National Natural Science Foundation of China under Grant No. 10575082the Natural Science Foundation of Gansu Province under Grant No. 3ZS061-A25-013the Natural Science Foundation of Northwest Normal University under Grant No. NWNU-KJCXGC-03-17
文摘A 2D square lattice is studied. By using the continuum approximation, we set up the differential equations of motion for an arbitrary particle in the square lattice which subjects to an external periodic substrate potential. The exact solitary waves of the system are found for special cases. We conclude that the adhesive force f and the angle between propagation directions of upper and lower layers can affect these waves.
文摘In this paper we give a characterization of planar lattices, and show that the sublattice L C Zn corresponding to the Hibi ideal of a finite distributive lattice L has a nice lattice basis if and only if L is planar. We also consider the Grobner basis of the lattice basis ideal attached to the planar lattices.
基金supported by National Natural Science Foundation of China (Grant No. 50976107 and 51206149)National Key Technology R&D Program of China (Grant No. 2009BAF39B01)Zhejiang Science Technology Project (Grant No. 2011C11073)
文摘The motion of micro-particles with different mass flow rate in the planer turbulent jet flow has been simulated, using LES method to obtain the flow vorticity evolution and Lagrangian method to track micro-particles. The re- suits showed that when the flow rate is small, the particles more likely to present in the vortex periphery, the dis- tribution pattern is similar to the flow pattern. When the flow rate is high, some particles will escape from the mo- tion region to the original static region, so that in the jet region, particles are relatively evenly distributed. When the flow field is full developed, the particles average concentration in the y direction affected by the mass flow rate relative slightly, the normalized mean particles concentrations at different flow rate were similar to Gaussian shape.
