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【期刊论文】Marangoni convection in model of floating zone under microgravity
曾忠, Z. Zenga, *, H. Mizusekia, K. Shimamuraa, K. Higashinob, T. Fukudaa, Y. Kawazoea
Journal of Crystal Growth 229(2001)601-604,-0001,():
-1年11月30日
Marangoni convection in a half-zone model, a simplification of the floating zone model, is steady and axisymmetric for Marangoni number Ma5Mac, but the azimuthal flow after instability (Ma>Mac) breaks the axial-symmetry, and m-foldsymmetry of the flow pattern is observed. The symmetry number m (azimuthal wave number) depends strongly on the aspect ratio, As (As=height/radius), of the half-zone. Based on the results of numerical simulation, the nature of the correlation between m and As is investigated.
A1., Convection, A1., Fluidflows, A1., Heat transfer, A2., Floating zone technique
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曾忠, 陈景秋, 赵万星
中国生物医学工程学报,2004,23(3):247~251,-0001,():
-1年11月30日
从理论和数值模拟两个方面分析了ESWL中的非线性的动力学焦点和实际焦点的位置,给出三种典型的动力学焦点的数值结果,说明非线性动力学焦点和实际焦点一般不是几何焦点,指出正确确定实际焦点在ESWL技术中的重要性。
体外冲击波碎石, 实际焦点, 动力学焦点
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【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.
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【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
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【期刊论文】CAN 5d TRANSITION-METAL MONOLAYERS BE MAGNETIC ON FERROMAGNETIC SUBSTRATE?
曾忠, Q. Sun, a, b Q. Wang, a J.Z. Yu, a z. Zen, a Z.Q. Li, a K. Ohnoa and Y. Kawazoea
Solid State Communications, Vol. 106, No.10, pp. 665-667, 1998,-0001,():
-1年11月30日
The magnetic properties of X/5Fe/X (X: Hf, Ta, W, Re, Os, Ir, Pt) have been studied by means of the full-potential linearized augmented-plane-wave method, in which the core states are treated fully relativistically and the valence states are treated semirelativistically and the generalized gradient approximations' (GCA) exchange-correlation potentials are employed for 5d elements. It has been found that Hf, Ta, W, Re and Os overlayers on Fe(0 0 1) are almost nonmagnetic. Following this trend, if the spin-orbit interactions are taken into account, the magnetism of Ir and Pt overlayers is expected to be killed as for the Ag(0 0 1) and Au(0 0 1) substrate. So the nonexistence of the magnetism for 5d overlayers is furtherly verified on ferromagnetic substrate besides on nonmagnetic substrate. Moreover, due to the more extended 5d orbitals as compared to those of 3d and 4d, much stronger hybridizations between the 5d states of the overlayer and the Fe substrate exist, which greatly suppress the magnetic moment of the interface Fe layer.
A., magnetic films and multilayers,, A., surfaces and interfaces.,
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