B.W. Li
,
X.Y. Tian
,
E.G. Wang
,
J.C. He
,
null
,
null
,
null
,
null
金属学报(英文版)
In recent years, thin slab continuous casting technology has been widely used to improve the quality of the product and to reduce
the cost. One of the challenges faced by this technology is to design reasonable flow patterns, which strongly affect the surface
and inner properties of the final slab in the mold. With the fixed scales and complex geometrical structures of nozzle and funnel
type mold, a series of numerical simulations are made to analyze the flow patterns in melt steel using finite volume method based
on structured body fitted coordinate grids. The CFD (computational fluid dynamics) package is validated first using one typical case described in previously published studies, and then it is developed to study the effect of operational parameters on fluid
flow in thin slab caster. Two operational parameters, casting speed and SEN depth (submerged entry nozzle), are mainly
considered for numerical analysis. On the basis of present simulations, the reasonable SEN submergence depths corresponding to different casting speeds are suggested according to fluid flow characteristics like, flow jet impingement on the narrow side of
the mold, flow speed of the melt steel beneath the meniscus and the recirculation region. This is the first stage of study on the numerical analysis of the whole thin slab casting process with electromagnetic brake.
关键词:
continuous casting
,
null
,
null
H.L. Zhang
,
E.G. Wang
,
G.L. Jia
金属学报(英文版)
The effects of linear electromagnetic stirring (EMS) on the solidification steacture of billet were investigated by experiments, and the electromagnetic fields and flow fields during the stirring process were analyzed by numerical simulation. The results show that the billet of almost 100% equiaxed grains can be obtained by applying linear EMS at the maximum intensity of 1414A.Hz1/2, while the maximum electromagnetic force and the maximum velocity in the molten steel are 6386N-m-3 and 0.22m.s-1,respectively. It is presented that the pulsating electromagnetic force perpendicular to the movement of the molten steel, is an important factor of increasing the equiaxed zone ratio in the solidification structure, which further prevents the appearance of white band and internal defects.
关键词:
linear EMS
,
null
,
null
,
null
,
null
Z.D. Qian
,
B.W. Li
,
E.G. Wang
金属学报(英文版)
A new treatment for interface of metal and dielectric in finite-difference time domain(FDTD) method was presented, further how and why this treatment should be as itis was explained. The FDTD method was developed to compute the low-frequencyelectromagnetic fields in the metal instead of the traditional high-frequency ones as itwas originally proposed. The computational results agreed well with the experimentalones.
关键词:
FDTD method
,
null
,
null
,
null
Communications in Theoretical Physics
By using the wavefunctions obtained from diagonalizing the complete d(3) energy matrix at normal and various pressures, the g factor of the ground state of SrTiO3:Cr3+ and its pressure-induced shift have been microscopically calculated. Only by taking the local strains around Cr3+ in SrTiO3:Cr3+ (which are about twice the bulk ones) and corresponding P-chi dependence, can we obtain a good agreement between the calculated result of pressure-induced shift of ground-state g factor and the experimental one. The physical origins of this pressure-induced shift have been explained. It is found that the change of Dq(-1) with pressure makes main contribution to the pressure-induced shift of ground-state g factor of SrTiO3:Cr3+. By using the wavefunctions obtained from diagonalizing the complete d3 energy matrix at normal pressure, the relevant matrix elements and accordingly strain-induced splittings of t(2)(3) E-2 and t(2)(3) (4)A(2) of SrTiO3:Cr3+ have been calculated. The important results of Y-c, Z(c), P-c and Q(c) have also been evaluated. It is the admixtures of basic wavefunctions resulted from the spin-orbit interaction and/or Coulomb interaction and/or Kramers degeneracy that make the strain-induced splittings of the levels nonzero. It is found that there are nonvanishing matrix elements of operators T2 xi, T2 eta and T2 zeta between wavefunctions with positive M-s and those with negative M-s', which have important effects on the strain-induced splittings of the levels.
关键词:
crystal fields;energy spectrum;g factors;high-pressure effect;strain-induced splitting;theoretical calculations;ruby;crystal
Journal of Physics and Chemistry of Solids
The g-shifts Ag( = g-g(s), where g(s) approximate to 2.0023 is the free-ion value) of the isoelectronic 3d(3) series Cr3+. Mn4+ and Fe5+ in SrTiO3 crystals are calculated from the high-order perturbation formula based on the cluster approach for 3d3 ion in cubic octahedral site. The formula includes not only the contribution from the crystal-field (CF) mechanism, but also that from the charge-transfer (CT) mechanism (which is omitted in the CF theory). From the calculations, it is found that the contribution Delta g(CT) from the CT mechanism in sign is contrary to the corresponding Delta g(CF) from the CF mechanism and the relative importance of CT mechanism (characterized by vertical bar Delta g(CT)/Delta g(CF)vertical bar) increases with the increasing valence state (and hence the atomic number) of 3d(3) ion. The positive g-shift Delta g of SrTiO3:Fe5+ is due mainly to the contribution of CT mechanism. So, for the explanations of g factors of the high valence state 3d" ions (e.g. Mn4+ and Fe5+) in crystals, the contributions from both CF and CT mechanisms should be taken into account. (c) 2005 Elsevier Ltd. All rights reserved.
关键词:
oxides;crystal fields;electronic paramagnetic resonance;optical;properties;electron-paramagnetic-resonance;atomic screening constants;scf;functions;luminescence;parameters;spectra;temperature;manganese;lattices;csmgbr3
贾昌春
,
A.Lahmam-Bennani
,
A.Duguet
,
L.Avaldi
,
M.Lecas
,
Dal Cappello
原子核物理评论
doi:10.3969/j.issn.1007-4627.2002.z1.007
通过Ar(e, 3e)五重微分截面3维图的理论与实验比较发现, 在低能电子入射的情况下, 理论与实验存在较大的偏差.
关键词:
(e,3e)
,
双电离
,
五重微分截面
王涛峰
,
朱丽萍
,
孟庆华
,
王黎明
,
韩洪银
,
夏海鸿
,
黎光武
,
屈从会
,
顾先宝
原子核物理评论
doi:10.3969/j.issn.1007-4627.2007.03.008
研制了屏栅电离室+△E-E望远镜探测器系统,系统的屏栅电离室用来测定252Cf自发裂变碎片的能量和相对于探测器系统轴线的发射角,与屏栅电离室耦合安装的△E-E望远镜探测器由一个薄的屏栅电离室(气体△E)和一个金硅面垒探测器(E)组成,用来确定互补碎片的电荷.用本系统对252Cf自发裂变碎片电荷分布进行了4个参数的关联测量,结果表明,这个探测器系统的电荷分辨能力Z/△Z好于40:1.
关键词:
屏栅电离室
,
△E-E望远镜
,
电荷分辨能力
