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961.
我们基于拟牛顿法的割线条件提出两种LS型共轭梯度法.有趣的是,我们提出的方法中对于βk的计算公式与戴和廖[3]提出的有相似的结构.但是,新方法能够在合理的假设下保证充分下降性,这一点是戴-廖方法所不具备的.在强Wolfe线搜索下,给出了新方法的全局收敛结果.数值结果论证了该方法的有效性. 相似文献
962.
This paper is to investigate the positive solutions of the systems of second-order ordinary differential equations with nonhomogeneous multi-point boundary conditions. By the lower and upper solutions method, Schauder fixed point theorem and fixed point index theory, under certain conditions, it is proved that there exist appropriate regions of parameters in which the problem has at least two, at least one or no positive solution. 相似文献
963.
给出了HR分解的分量型和范数型的一阶扰动界.对于范数型,新的精化扰动界至少优于已有结果,特别的,新的关于R因子的扰动界远远优于已有的扰动界. 相似文献
964.
Bing Sun 《Nonlinear Analysis: Real World Applications》2012,13(1):325-332
In this paper, the optimal distributed control of the viscous Dullin-Gottwald-Holm equation is investigated. Adopting the Dubovitskii and Milyutin functional analytical approach, we obtain the Pontryagin maximum principle of the system. The necessary optimality condition is established for an optimal control problem in fixed final horizon case. Finally, an illustrative example is also given. 相似文献
965.
《复变函数与椭圆型方程》2012,57(15):1125-1136
The aim of this article is to give explicit representations for solutions of the Robin boundary value problem for the Cauchy-Riemann operator [image omitted]. In the homogeneous cases we investigate the Robin boundary condition in a more general form. Finally, we give solutions of the corresponding higher-order operators. 相似文献
966.
Demonstration of the approximation of eliminating atomic excited populations in an atom-cavity system
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Using the master equation approach to a V-type three-level atom inside a high-finesse single-mode cavity in the strong coupling condition,we demonstrate the approximation of eliminating populations of atomic excited states,which is widely used in the field of the atom-cavity systems [Hechenblaikner G,Gangl M,Horak P and Ritsch H 1998 Phys.Rev.A 58 3030];Liu L W,Tan T and Xu Y 2008 J.Mod.Opt.56 968;Cho J,Angelakis D G and Bose S 2008 Phys.Rev.A 78 062338.This is reflected in the deviation of the population δ,of which the value is 10~(-3)~10~(-2).We further find the deviation of the dipole force and demonstrate that the deviation of atomic population will not notably affect the dipole force of the atom in the strong coupling condition.A relevant experimental case is also presented. 相似文献
967.
A version of Hill's lemma for Cosserat continuum 总被引:4,自引:0,他引:4
On the basis of Hill's lemma for classical Cauchy continuum, a version of Hill's lemma for micro-macro homogenization modeling of heterogeneous Cosserat continuum is presented in the flame of average-field theory. The admissible boundary conditions required to prescribe on the representative volume element for the modeling are extracted and discussed to ensure the satisfaction of Hill-Mandel energy condition and the first-order average field theory. 相似文献
968.
Francisco J. Valdés-Parada Jose Alvarez-Ramirez Benoît Goyeau J. Alberto Ochoa-Tapia 《Transport in Porous Media》2009,78(3):459-476
In this paper, mass transfer at the fluid–porous medium boundaries is studied. The problem considers both diffusive and convective
transport, along with adsorption and reaction effects in the porous medium. The result is a mass flux jump condition that
is expressed in terms of effective transport coefficients. Such coefficients (a total dispersion tensor and effective reaction
and adsorption coefficients) may be computed from the solution of the corresponding closure problem here stated and solved
as a function of the Péclet number (Pe), the porosity and a local Thiele modulus. For the case of negligible convective transport (i.e., ), the closure problem reduces to the one recently solved by the authors for diffusion and reaction between a fluid and a
microporous medium. 相似文献
969.
Min Chan Kim Do-Young Yoon Joo Hyung Moon Chang Kyun Choi 《Transport in Porous Media》2008,74(3):369-380
When porous media saturated with initially stagnant cold water around the density maximum temperature are cooled from above,
convection may be induced in an unstable lower layer. In this study, the onset of buoyancy-driven convection during time-dependent
cooling is investigated using the propagation theory, which transforms disturbance equations similarly, and also considering
the density inversion effect. The critical Darcy–Rayleigh number Ra
D,c is found as a function of the dimensionless density maximum temperature θ
max. For Ra
D > Ra
D,c the dimensionless critical time τ
c to mark the onset of instability is presented as a function of Ra
D and θ
max. These critical conditions are compared with previous theoretical results. 相似文献
970.
The composite under investigation consists of an elastoplastic matrix reinforced by elastic particles or weakened by pores. The material forming the matrix is pressure-sensitive. The Drucker–Prager yield criterion and a one-parameter non-associated flow rule are employed to formulate the yield behavior of the matrix. The objective of this work is to estimate the effective elastoplastic behavior of the composite under isotropic tensile and compressive loadings. To achieve this objective, the composite sphere assemblage model of Hashin [Z. Hashin, The elastic moduli of heterogeneous materials, ASME J. Appl. Mech. 29 (1962) 143–150] is used. Exact solutions are thus derived as estimations for the effective secant and tangent bulk moduli of the composite. The effects of the loading modes and phase properties on the effective elastoplastic behavior of the composite are analytically and numerically evaluated. 相似文献