The results of experimental investigation of laminar-turbulent transition in three-dimensional flow under the high continuous pressure gradient including the flow with local boundary layer separation are presented. Th...The results of experimental investigation of laminar-turbulent transition in three-dimensional flow under the high continuous pressure gradient including the flow with local boundary layer separation are presented. The experimental studies were performed within the Mach number range from 4 to 6 and Reynolds number 10-60×106 1/m, the angles of attack were 0° and 5°. The experiments were carried out on the three-dimensional convergent inlet model with and without sidewalls. The influence of artificial tubulator of boundary layer on transition and flow structure was studied. The conducted researches have shown that adverse pressure gradient increase hastens transition and leads to decrease of transition area length. If pressure gradient rises velocity profile fullness increases and profile transformation from laminar to turbulent occurs. As a result of it the decrease of separation area length occurs. The same effect was reached with Reynolds number increase. These results are compared with the data on two-dimensional model with longitudinal curvature.展开更多
With the method of Green's function, we investigate the energy spectra of two-component ultracold bosonic atoms in optical lattices. We End that there are two energy bands for each component. The critical conditio...With the method of Green's function, we investigate the energy spectra of two-component ultracold bosonic atoms in optical lattices. We End that there are two energy bands for each component. The critical condition of the superfluid-Mott insulator phase transition is determined by the energy band structure. We also find that the nearest neighboring and on-site interactions fail to change the structure of energy bands, but shift the energy bands only. According to the conditions of the phase transitions, three stable superfluid and Mott insulating phases can be found by adjusting the experiment parameters. We also discuss the possibility of observing these new phases and their transitions in further experiments.展开更多
We investigate the phenomena of symmetry breaking and phase transition in theground state of Bose-Einstein condensates (BECs) trapped in a double square well and in an opticallattice well, respectively. By using stand...We investigate the phenomena of symmetry breaking and phase transition in theground state of Bose-Einstein condensates (BECs) trapped in a double square well and in an opticallattice well, respectively. By using standing-wave expansion method, we present symmetric andasymmetric ground state solutions of nonlinear Schroedinger equation (NLSE) with a symmetric doublesquare well potential for attractive nonlinearity. In particular, we study the ground state wavefunction's properties by changing the depth of potential and atomic interactions (here we restrictourselves to the attractive regime). By using the Fourier grid Hamiltonian method, we also reveal aphase transition of BECs trapped in one-dimensional optical lattice potential.展开更多
The magnetic phase transition and magneto- caloric effect of Gd5Si1.85Ge2.15 alloy are studied. The alloy was prepared from distilled commercial gadolinium. The major impurities (in wt.%) in the distilled commercial G...The magnetic phase transition and magneto- caloric effect of Gd5Si1.85Ge2.15 alloy are studied. The alloy was prepared from distilled commercial gadolinium. The major impurities (in wt.%) in the distilled commercial Gd are 0.016 O, 0.0054 C, and 0.0016 N. The impurities are higher than those in the high pure Gd but lower than those in commercial Gd. The results of X-ray diffraction and magnetic susceptibility show that there exists the first-order magnetic phase transition in the Gd5Si1.85Ge2.15 alloy at 253 K. The maximum of magnetic entropy change Smax is 12.5 J/kg·K near the temperature of magnetic phase transition in the alloy.展开更多
The transition between nano-diamond(n-D) and nano-graphite(n-G) were modeled based on the extrapolation of the bulk diamond-graphite equilibrium phase boundary in the temperature-pressure diagram to the nano-size regi...The transition between nano-diamond(n-D) and nano-graphite(n-G) were modeled based on the extrapolation of the bulk diamond-graphite equilibrium phase boundary in the temperature-pressure diagram to the nano-size region. It is found that in comparison with n-G, the stability of n-D increases as size and temperature decrease. However, n-D is not the most stable phase in comparison with fullerenes(C60) at the nanoscale by considering the heat of formation.展开更多
文摘The results of experimental investigation of laminar-turbulent transition in three-dimensional flow under the high continuous pressure gradient including the flow with local boundary layer separation are presented. The experimental studies were performed within the Mach number range from 4 to 6 and Reynolds number 10-60×106 1/m, the angles of attack were 0° and 5°. The experiments were carried out on the three-dimensional convergent inlet model with and without sidewalls. The influence of artificial tubulator of boundary layer on transition and flow structure was studied. The conducted researches have shown that adverse pressure gradient increase hastens transition and leads to decrease of transition area length. If pressure gradient rises velocity profile fullness increases and profile transformation from laminar to turbulent occurs. As a result of it the decrease of separation area length occurs. The same effect was reached with Reynolds number increase. These results are compared with the data on two-dimensional model with longitudinal curvature.
文摘With the method of Green's function, we investigate the energy spectra of two-component ultracold bosonic atoms in optical lattices. We End that there are two energy bands for each component. The critical condition of the superfluid-Mott insulator phase transition is determined by the energy band structure. We also find that the nearest neighboring and on-site interactions fail to change the structure of energy bands, but shift the energy bands only. According to the conditions of the phase transitions, three stable superfluid and Mott insulating phases can be found by adjusting the experiment parameters. We also discuss the possibility of observing these new phases and their transitions in further experiments.
文摘We investigate the phenomena of symmetry breaking and phase transition in theground state of Bose-Einstein condensates (BECs) trapped in a double square well and in an opticallattice well, respectively. By using standing-wave expansion method, we present symmetric andasymmetric ground state solutions of nonlinear Schroedinger equation (NLSE) with a symmetric doublesquare well potential for attractive nonlinearity. In particular, we study the ground state wavefunction's properties by changing the depth of potential and atomic interactions (here we restrictourselves to the attractive regime). By using the Fourier grid Hamiltonian method, we also reveal aphase transition of BECs trapped in one-dimensional optical lattice potential.
基金supported by the National Natural Science Foundation of China(Grant No.50071006)the“863”Program(Grant No.2002AA324101).
文摘The magnetic phase transition and magneto- caloric effect of Gd5Si1.85Ge2.15 alloy are studied. The alloy was prepared from distilled commercial gadolinium. The major impurities (in wt.%) in the distilled commercial Gd are 0.016 O, 0.0054 C, and 0.0016 N. The impurities are higher than those in the high pure Gd but lower than those in commercial Gd. The results of X-ray diffraction and magnetic susceptibility show that there exists the first-order magnetic phase transition in the Gd5Si1.85Ge2.15 alloy at 253 K. The maximum of magnetic entropy change Smax is 12.5 J/kg·K near the temperature of magnetic phase transition in the alloy.
基金Project(2004CB619301) supported by the National Basic Research and Development Program Project(50025101) sup ported by the National Natural Science Foundation of China
文摘The transition between nano-diamond(n-D) and nano-graphite(n-G) were modeled based on the extrapolation of the bulk diamond-graphite equilibrium phase boundary in the temperature-pressure diagram to the nano-size region. It is found that in comparison with n-G, the stability of n-D increases as size and temperature decrease. However, n-D is not the most stable phase in comparison with fullerenes(C60) at the nanoscale by considering the heat of formation.
