The mechanism of the response motion of a suspended particle to turbulent motion of its surrounding fluid is different according to si:e of turbulent eddies. The particle is dragged by the viscous force of large eddie...The mechanism of the response motion of a suspended particle to turbulent motion of its surrounding fluid is different according to si:e of turbulent eddies. The particle is dragged by the viscous force of large eddies, and meanwhile driven randomly by small eddies. Based on this understanding, the dispersion of a particle with finite size in a homogeneous isotropic turbulence is calculated in this study. Results show that there are two competing effects: when enhanced by the inertia of a particle, the long-term particle diffusivity is reduced by the finite size of the particle.展开更多
The plasma wave instability in rectangle field effect transistors （FETs） is studied with electron diffusion current density by quantum hydrodynamic model in this paper. General dispersion relation including effects ...The plasma wave instability in rectangle field effect transistors （FETs） is studied with electron diffusion current density by quantum hydrodynamic model in this paper. General dispersion relation including effects of electrical thermal motion, external friction associated with electron scattering effect, electron exchange-correlation contributions and quantum effects were obtained for rectangle FETs. The electron diffusion current density term is considered for further analysis in this paper. It is found that the quantum effects, the electron diffusion current density and electrical thermal motion enhance the radiation power and frequencies. But the electron exchange- correlation effects and the electron scattering effects reduce the radiation power and frequencies. Results showed that a transistor has advantages for the realization of practical terahertz sources.展开更多
Everyone has his heroes, like the college coaches, many of them play a important role in our college life, and they hve a legendary life here at the same time. In America, college student pay attention to NCAA （Natio...Everyone has his heroes, like the college coaches, many of them play a important role in our college life, and they hve a legendary life here at the same time. In America, college student pay attention to NCAA （National Collegiate Athletic Association）, there are many famous coaches in it, such as Nich Saban, Jerry Tarkanian, and more. The authors are very interested in the competitive life of those who are the top five coaches in the world. So the authors concentrate on the winning rate, the contribution rate, and the cycle of the honors to evaluate each coach, by standardizing the metrics, they get the final scores of each metric for basketball; according to the scores, they get the top five coaches in a century. And in this paper, the authors also take the gender and timeline into account.展开更多
文摘The mechanism of the response motion of a suspended particle to turbulent motion of its surrounding fluid is different according to si:e of turbulent eddies. The particle is dragged by the viscous force of large eddies, and meanwhile driven randomly by small eddies. Based on this understanding, the dispersion of a particle with finite size in a homogeneous isotropic turbulence is calculated in this study. Results show that there are two competing effects: when enhanced by the inertia of a particle, the long-term particle diffusivity is reduced by the finite size of the particle.
基金supported by National Natural Science Foundation of China (No. 10975114)Research Projects of Higher Education of Gansu Province (2017A-016)
文摘The plasma wave instability in rectangle field effect transistors （FETs） is studied with electron diffusion current density by quantum hydrodynamic model in this paper. General dispersion relation including effects of electrical thermal motion, external friction associated with electron scattering effect, electron exchange-correlation contributions and quantum effects were obtained for rectangle FETs. The electron diffusion current density term is considered for further analysis in this paper. It is found that the quantum effects, the electron diffusion current density and electrical thermal motion enhance the radiation power and frequencies. But the electron exchange- correlation effects and the electron scattering effects reduce the radiation power and frequencies. Results showed that a transistor has advantages for the realization of practical terahertz sources.
文摘Everyone has his heroes, like the college coaches, many of them play a important role in our college life, and they hve a legendary life here at the same time. In America, college student pay attention to NCAA （National Collegiate Athletic Association）, there are many famous coaches in it, such as Nich Saban, Jerry Tarkanian, and more. The authors are very interested in the competitive life of those who are the top five coaches in the world. So the authors concentrate on the winning rate, the contribution rate, and the cycle of the honors to evaluate each coach, by standardizing the metrics, they get the final scores of each metric for basketball; according to the scores, they get the top five coaches in a century. And in this paper, the authors also take the gender and timeline into account.
