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101.
K. NarooeiA. Karimi Taheri 《Applied Mathematical Modelling》2012,36(5):2128-2141
In this paper the previous velocity field proposed by the authors for the prediction of strain field and deformation load of circular cross section billet in ECAE process has been extended to take into account the deformation behavior of bimetal circular billet in the same process. Accordingly, using Bezier method, as a robust method for determining the geometry of the streamlines, the strain field developed in the circular bimetal billet is calculated. Then, based on the kinematically admissible velocity and strain fields and using the upper bound theorem the ECAE load is predicted. It was found that at constant inner corner angle of ECAE die, with decreasing of outer curve corner the inhemogenity of strain distribution is decreased and the ECAE force is increased. Also, at a constant outer curve corner, by decreasing the inner corner angle, the extrusion load is increased. A good agreement was found between the predicted and experimental results. 相似文献
102.
103.
A.H. Khan Imtiyaz A. Shah M. Ahsanullah 《Journal of the Egyptian Mathematical Society》2012,20(3):211-214
Distributional properties of two non-adjacent dual generalized order statistics have been used to characterize distributions. Further, one sided contraction and dilation for the dual generalized order statistics are discussed and then the results are deduced for generalized order statistics, order statistics, lower record statistics, upper record statistics and adjacent dual generalized order statistics. 相似文献
104.
Robert A. Van Gorder K. Vajravelu F. Talay Akyildiz 《ournal of non Newtonian Fluid Mechanics》2009,161(1-3):94-100
In this paper, we consider viscoelastic stresses T11, T12 and T22 arising in the stagnation flow of a dilute polymer solution; in particular, we consider an upper convected Maxwell (UCM) fluid. We present exact solutions to the coupled partial differential equations describing the viscoelastic stresses and deduce the results for the stress T22 of Becherer et al. [P. Becherer, A.N. Morozov, W. van Saarloos, Scaling of singular structures in extensional flow of dilute polymer solutions, J. Non-Newtonian Fluid Mech. 153 (2008) 183–190]. As we considered the viscoelastic stresses over two spatial variables, we are able to study the effect of variable boundary data at the inflow. As such, our results are applicable to a wider range of fluid flow problems. 相似文献
105.
S.M. Keralavarma 《Journal of the mechanics and physics of solids》2010,58(6):874-3067
Plastic constitutive relations are derived for a class of anisotropic porous materials consisting of coaxial spheroidal voids, arbitrarily oriented relative to the embedding orthotropic matrix. The derivations are based on nonlinear homogenization, limit analysis and micromechanics. A variational principle is formulated for the yield criterion of the effective medium and specialized to a spheroidal representative volume element containing a confocal spheroidal void and subjected to uniform boundary deformation. To obtain closed form equations for the effective yield locus, approximations are introduced in the limit-analysis based on a restricted set of admissible microscopic velocity fields. Evolution laws are also derived for the microstructure, defined in terms of void volume fraction, aspect ratio and orientation, using material incompressibility and Eshelby-like concentration tensors. The new yield criterion is an extension of the well known isotropic Gurson model. It also extends previous analyses of uncoupled effects of void shape and material anisotropy on the effective plastic behavior of solids containing voids. Preliminary comparisons with finite element calculations of voided cells show that the model captures non-trivial effects of anisotropy heretofore not picked up by void growth models. 相似文献
106.
G是一个无K4-图子式、顶点数为n的简单图,p(G)是图G的谱半径.本文得出一个关于p(G)的上确界:等式成立当且仅当 G ≌K2 (n-2)K1,其中 G1 G2是由 G1∪G2组成、并且G1中的第一个点和G2中的每一个点之间都有一条边相连:(n-2)K1表示(n-2)个孤立点的集合. 相似文献
107.
Antonella Fiacca Nikolaos Matzakos Nikolaos S. Papageorgiou Raffaella Servadei 《Proceedings Mathematical Sciences》2001,111(4):489-508
In this paper we study nonlinear elliptic boundary value problems with monotone and nonmonotone multivalued nonlinearities.
First we consider the case of monotone nonlinearities. In the first result we assume that the multivalued nonlinearity is
defined on all ℝ. Assuming the existence of an upper and of a lower solution, we prove the existence of a solution between
them. Also for a special version of the problem, we prove the existence of extremal solutions in the order interval formed
by the upper and lower solutions. Then we drop the requirement that the monotone nonlinearity is defined on all of ℝ. This
case is important because it covers variational inequalities. Using the theory of operators of monotone type we show that
the problem has a solution. Finally in the last part we consider an eigenvalue problem with a nonmonotone multivalued nonlinearity.
Using the critical point theory for nonsmooth locally Lipschitz functionals we prove the existence of at least two nontrivial
solutions (multiplicity theorem). 相似文献
108.
本文用上,下解方法,根据Leray-Schauder不动点定理给出一类带有非线性边界条件的脉冲微分方程边值问题解的存在性定理。 相似文献
109.
The Upper Semicontinuity of Random Attractors for Non-Autonomous Stochastic Plate Equations with Multiplicative Noise and Nonlinear Damping
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Based on the existence of pullback attractors for the non-autonomous stochastic plate equations with multiplicative noise and nonlinear damping defined in the entire space $\mathbb{R}^n$ by Xiaobin Yao in \cite{Yao4}, in the paper, we further investigate the upper semicontinuity of pullback attractors for the problem. 相似文献
110.
二阶混合型脉冲微分-积分方程周期边值问题解的存在性 总被引:5,自引:0,他引:5
本文利用上下解方法再结合不动点理论给出了二阶混合型脉冲微分-积分方程周期边值问题解的存在性. 相似文献