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【期刊论文】NUMERICAL SIMULATION OF CONVECTION DEPTH IN SHEAR CELL UNDER MICROGRAVITY
曾忠, Z. Zeng, H. Mizuseki, K. Ichinoseki, K. Higashino, and Y. Kawazoe
Adv. Space Rex Vol. 24, No.10, pp. 1321-1324, 199,-0001,():
-1年11月30日
By applying the idea of an isotope trace experiment, the concept of isotope trace in hydrodynamics simulation is proposed. The isotope concentration is conceived as a numerical marker to trace the convection and estimate numerically the convection depth due to shearing in shear cell under microgravity. Two different shearing rates, 2mm/s and 20mm/s, are investigated, and results demonstrate that the isotope depths are same for both cases at the termination of shearing, but the effect of residual flow field after shearing is different.
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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
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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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【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
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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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