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71.
Summary The Korteweg-de Vries equation for ion acoustic waves in the presence of weakly relativistic ion streaming velocity is derived
in a magnetic plasma. It is found that relativistic effects are important in the solitary wave propagation for both fast and
slow modes. Earlier results are reconfirmed.
To speed up publication, the authors of this paper have agreed to not receive the proofs for correction. 相似文献
72.
为达到合肥光源二期工程通用模式的设计流强,在储存环上选择垂直方向β函数比较大的位置增加一组八极磁铁。该组八极磁铁对水平方向动力学孔径影响很小,虽然垂直方向动力学孔径明显减小,但仍然大于物理孔径,不会影响束流的注入积累过程。该组八极磁铁产生的垂直方向振荡频率分散可以提供ms量级的Landau阻尼时间,将明显增强抑制垂直方向束流集体不稳定性的能力。该组八极磁铁投入运行后,合肥光源注入积累过程明显改善,注入流强从无八极磁铁时的约100 mA提高到330 mA左右。 相似文献
73.
Jaume Martí-Farré 《Discrete Applied Mathematics》2006,154(3):552-563
The characterization of ideal access structures and the search for bounds on the optimal information rate are two important problems in secret sharing. These problems are studied in this paper for access structures with intersection number equal to one, that is, structures such that there is at most one participant in the intersection of any two different minimal qualified subsets. The main result in this work is the complete characterization of the ideal access structures with intersection number equal to one. In addition, bounds on the optimal information rate are provided for the non-ideal case. 相似文献
74.
75.
The global existence of solutions to a damped MHD system in Besov spaces is obtained. This research is motivated by the open question [Wu et al., J. Nonlinear Sci. 25 (2015), 157–192, Remark 5.1] on the possibility of extension to the existence of global small solutions from a potential Banach space to a Besov space. The present result positively confirms the open question. What is more, the initial data are not required to be uniformly small. 相似文献
76.
A low order nonconforming mixed finite element method (FEM) is established for the fully coupled non-stationary incompressible magnetohydrodynamics (MHD) problem in a bounded domain in 3D. The lowest order finite elements on tetrahedra or hexahedra are chosen to approximate the pressure, the velocity field and the magnetic field, in which the hydrodynamic unknowns are approximated by inf-sup stable finite element pairs and the magnetic field by $H^1(\Omega)$-conforming finite elements, respectively. The existence and uniqueness of the approximate solutions are shown. Optimal order error estimates of $L^2(H^1)$-norm for the velocity field, $L^2(L^2)$-norm for the pressure and the broken $L^2(H^1)$-norm for the magnetic field are derived. 相似文献
77.
The series solutions of unsteady flows of a viscous incompressible electrically conducting fluid caused by an impulsively
rotating infinite disk are given by means of an analytic technique, namely the homotopy analysis method. Using a set of new
similarity transformations, we transfer the Navier–Stokes equations into a pair of nonlinear partial differential equations.
The convergent series solutions are obtained, which are uniformly valid for all dimensionless time 0 ≤ τ < ∞ in the whole
spatial region 0 ≤ η < ∞. To the best of our knowledge, such kind of series solutions have never been reported. The effect
of magnetic number on the velocity is investigated. 相似文献
78.
J.C. Umavathi 《International Journal of Non》2005,40(1):91-101
The problem of combined free and forced convective magnetohydrodynamic flow in a vertical channel is analysed by taking into account the effect of viscous and ohmic dissipations. The channel walls are maintained at equal or at different constant temperatures. The velocity field and the temperature field are obtained analytically by perturbation series method and numerically by finite difference technique. The results are presented for various values of the Brinkman number and the ratio of Grashof number to the Reynolds number for both equal and different wall temperatures. Nusselt number at the walls is determined. It is found that the viscous dissipation enhances the flow reversal in the case of downward flow while it counters the flow in the case of upward flow. It is also found that the analytical and numerical solutions agree very well for small values of ε. 相似文献
79.
An analysis is carried out to study the effects of localized heating (cooling), suction (injection), buoyancy forces and magnetic field for the mixed convection flow on a heated vertical plate. The localized heating or cooling introduces a finite discontinuity in the mathematical formulation of the problem and increases its complexity. In order to overcome this difficulty, a non-uniform distribution of wall temperature is taken at finite sections of the plate. The nonlinear coupled parabolic partial differential equations governing the flow have been solved by using an implicit finite-difference scheme. The effect of the localized heating or cooling is found to be very significant on the heat transfer, but its effect on the skin friction is comparatively small. The buoyancy, magnetic and suction parameters increase the skin friction and heat transfer. The positive buoyancy force (beyond a certain value) causes an overshoot in the velocity profiles.A
mass transfer constant
- B
magnetic field
- Cfx
skin friction coefficient in the x-direction
- Cp
specific heat at constant pressure, kJ.kg–1.K
- Cv
specific heat at constant volume, kJ.kg–1.K–1
- E
electric field
- g
acceleration due to gravity, 9.81 m.s–2
- Gr
Grashof number
- h
heat transfer coefficient, W.m2.K–1
- Ha
Hartmann number
- k
thermal conductivity, W.m–1.K
- L
characteristic length, m
- M
magnetic parameter
- Nux
local Nusselt number
- p
pressure, Pa, N.m–2
- Pr
Prandtl number
- q
heat flux, W.m–2
- Re
Reynolds number
- Rem
magnetic Reynolds number
- T
temperature, K
- To
constant plate temperature, K
- u,v
velocity components, m.s–1
- V
characteristic velocity, m.s–1
- x,y
Cartesian coordinates
-
thermal diffusivity, m2.s–1
-
coefficient of thermal expansion, K–1
- ,
transformed similarity variables
-
dynamic viscosity, kg.m–1.s–1
- 0
magnetic permeability
-
kinematic viscosity, m2.s–1
-
density, kg.m–3
-
buoyancy parameter
-
electrical conductivity
-
stream function, m2.s–1
-
dimensionless constant
-
dimensionless temperature, K
- w,
conditions at the wall and at infinity 相似文献
80.
Adel A. Megahed 《International Journal of Non》2003,38(4):513-520
Heat and mass transfer along a semi-infinite vertical flat plate under the combined buoyancy force effects of thermal and species diffusion is investigated in the presence of a strong non-uniform magnetic field and the Hall currents are taken into account. The induced magnetic field due to the motion of the electrically conducting fluid is negligible. This assumption is valid for a small magnetic Reynolds number. The similarity solutions are obtained using the scale group of transformations. These are the only symmetry transformations admitted by the field equations. The non-linear boundary layer equations with the boundary conditions are transferred to a system of non-linear ordinary differential equations with the appropriate boundary conditions. Furthermore, the similarity equations are solved numerically by using a fourth order Runge-Kutta scheme with the shooting method. Numerical results for the velocity profiles, the temperature profiles and the concentration profiles are presented graphically for various values of the magnetic parameter M in the range of 0-1 with the Hall parameter m taking the values 0.5, 1, 2, and 3. 相似文献