The quadrupole mode frequency, the monopole mode frequency, and the critical rotational frequency for stirring a single vortex nucleation along the BEC-BCS crossover are obtained. The results show that, in a rotating ...The quadrupole mode frequency, the monopole mode frequency, and the critical rotational frequency for stirring a single vortex nucleation along the BEC-BCS crossover are obtained. The results show that, in a rotating anisotropic anharmonic trap, the quadrupole mode frequency and the critical rotational frequency for stirring a single vortex nucleation are modified significantly when the system crosses from the BEC side to the BCS side： the anisotropy of the trap induces a downshiff of the quadrupole mode frequency and the critical rotational frequency and helps the vortex formation in the system, while an anharmonic trap induces an upshift of the quadrupole mode frequency and the critical rotational frequency and suppresses the vortex formation in the system.展开更多
Entrance region may have important effect on gases flow characteristics in micro-channels. It's concluded in the available papers that the entrance effect causes significant difference. An experimental system of s...Entrance region may have important effect on gases flow characteristics in micro-channels. It's concluded in the available papers that the entrance effect causes significant difference. An experimental system of single-phase gas flow characteristics in microchannels was set up. Flow characteristics of nitrogen in PEEK polymer micro-tube (hydraulic diameter is 553btm) was studied experimentally. According to the data of nitrogen flow in the micro-tube with the length ranging from 0. 1m to1.524m, it is shown that the friction constant becomes higher when the tube becomes shorter. By using pipe cutting methods, it's confirmed that entrance effect is one of the key factors that cause friction constant higher than conventional theory. It's found that friction constant of fully developed flow is lower than the value predicted by conventional theory in turbulent region. The result indicates that the flow transition occurs at Reynolds number ranging from 1600-2000. The phenomenon of obvious early transition is not found.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos. 10774120 and 10975114 and by Natural Science Foundation of Northwest Normal University under Grant Nos. NWNU-KJCXCC-03-48 and NWNU-KJCXGC-03-17
文摘The quadrupole mode frequency, the monopole mode frequency, and the critical rotational frequency for stirring a single vortex nucleation along the BEC-BCS crossover are obtained. The results show that, in a rotating anisotropic anharmonic trap, the quadrupole mode frequency and the critical rotational frequency for stirring a single vortex nucleation are modified significantly when the system crosses from the BEC side to the BCS side： the anisotropy of the trap induces a downshiff of the quadrupole mode frequency and the critical rotational frequency and helps the vortex formation in the system, while an anharmonic trap induces an upshift of the quadrupole mode frequency and the critical rotational frequency and suppresses the vortex formation in the system.
基金supported by the National Natural Science Foundation of China (No. 50776006)"863" plan (No. 2006AA05Z228)Technological Innova tion Fund of Excellent Doctoral Candidate of Beijing Jiaotong University (No. 48013)
文摘Entrance region may have important effect on gases flow characteristics in micro-channels. It's concluded in the available papers that the entrance effect causes significant difference. An experimental system of single-phase gas flow characteristics in microchannels was set up. Flow characteristics of nitrogen in PEEK polymer micro-tube (hydraulic diameter is 553btm) was studied experimentally. According to the data of nitrogen flow in the micro-tube with the length ranging from 0. 1m to1.524m, it is shown that the friction constant becomes higher when the tube becomes shorter. By using pipe cutting methods, it's confirmed that entrance effect is one of the key factors that cause friction constant higher than conventional theory. It's found that friction constant of fully developed flow is lower than the value predicted by conventional theory in turbulent region. The result indicates that the flow transition occurs at Reynolds number ranging from 1600-2000. The phenomenon of obvious early transition is not found.
