已为您找到该学者15条结果 成果回收站
【期刊论文】Direct numerical simulation of oscillatory Marangoni convection in cylindrical liquid bridges
曾忠, Z. Zenga, *, H. Mizusekia, K. Higashinob, Y. Kawazoea
Journal of Crystal Growth 204(1999)395-404,-0001,():
-1年11月30日
A three-dimensional oscillatory Marangoni (thermocapillary) convection with Prandtl number Pr=16.0849 and Marangoni number Ma"3.30508]104 in a large aspect ratio (As=H/R) range, As=0.2-4, in a silicone oil liquid bridge with a non-deformable cylindrical surface is investigated by the anite volume method. The azimuthal wave numbers 1, 2, 3, 4, 5, 6, 10 and 16 are obtained for different aspect ratios, As. The dimensionless main frequency f*p=fMa-1/2H2/k of periodic or quasi-periodic temperature oscillations strongly depends on aspect ratio, As. f*p increases with the increment of As with approximately a bi-linear relation, and its gradient for As=0.2-1 is less than that for As>1. The periodic and quasi-periodic oscillations are found to depend on aspect ratio, As, for fixed Pr and Ma.
Marangoni convection, Thermocapillary, Floating zone, Half-zone
-
36浏览
-
0点赞
-
0收藏
-
0分享
-
47下载
-
0
-
引用
曾忠, Yong Guo a, c, ∗, Jun-Qiang Lu b, Zhong Zeng c, Qian Wang c, Bing-Lin Gu a, Yoshiyuki Kawazoe c
Physics Letters A 284(2001)205-215,-0001,():
-1年11月30日
We present tight-binding Green's function investigations of the influence of quantum sizes and the temperature on spin tunneling transport through a tunable ZnSe/Zn1-xMnxSe multilayers under an external electric field. It is found that the degree of polarization can be significantly induced by the size of the corresponding structure. As the size of the multilayers is increasing, both the transmission spectra and the current density spectra become more complicated and the degree of spin polarization is higher. It is also found that the degree of the spin polarization is drastically reduced as the temperature is increasing.
Spin polarization, Tunneling, Heterojunctions, Semimagnetic semiconductor
-
40浏览
-
0点赞
-
0收藏
-
0分享
-
31下载
-
0
-
引用
【期刊论文】Electron-spin polarization in magnetically modulated quantum structures
曾忠, Yong Guo, Bing-Lin Gu, Zhong Zeng, Jing-Zhi Yu, and Yoshiyuki Kawazoe
PHYSICAL REVIEW B VOLUME 62, NUMBER 4 15 JULY 2000-II,-0001,():
-1年11月30日
The spin-dependent electron resonant tunneling through magnetically modulated quantum structures has been investigated with and without an external electric field. The spin polarization is found to be strongly dependent on the magnetic configuration, the applied bias, the incident electron energy, and the incident wave vector. It is shown that an unpolarized beam of conducting electrons can be strongly polarized for an electron tunneling through magnetic-barrier structures, which is an arrangement with unidentical magnetic barriers and wells. The external electric field greatly changes the spin polarization of electrons for small electronic energies, where the electron-spin polarization exhibits considerable wave-vector-dependent features.
-
41浏览
-
0点赞
-
0收藏
-
0分享
-
34下载
-
0
-
引用
曾忠, Yong Guo a, b, ), Bing-Lin Gu a, Zhong Zeng b, Yoshiyuki Kawazoe b
Physics Letters A 261(1999)114-118,-0001,():
-1年11月30日
Electronic states and tunneling properties in step-barrier structures have been investigated. The results indicate that there exists quasibound states in step-barrier structure both at zero bias and under an applied bias. Size effect on negative-differential resistances is examined and the condition for obtaining larger current peak-to-valley ratios has been discussed.
Heterojunctions, Resonant tunneling, Quasibound states, Negative-differential resistance
-
25浏览
-
0点赞
-
0收藏
-
0分享
-
49下载
-
0
-
引用
【期刊论文】The local magnetism of Fe impurity in Nbn and NbnMom clusters
曾忠, Q. Wanga, b, Q. Suna, *, J.Z. Yub, Z. Zengb, Y. Kawazoeb
Journal of Magnetism and Magnetic Materials 184(1998)106-110,-0001,():
-1年11月30日
The local magnetic properties of impurity Fe in small Nbn and NbnMom clusters have been studied by using a linear combination of atomic orbitals approach with the density functional formalism, and the Kohn
Impurity effect, Local spin-density functional approximation, Cluster
-
19浏览
-
0点赞
-
0收藏
-
0分享
-
28下载
-
0
-
引用