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91.
Jean-Paul Penot 《Set-Valued Analysis》2001,9(1-2):131-157
We show that three important topics in nonlinear analysis and optimization are intimately related: the theory of perturbations, the notion of well-posedness and variational principles in the sense of Ekeland, Borwein–Preiss and Deville–Godefroy–Zizler. The concept of genericity and the new notion of flexible perturbation play a key role in these connections. This notion enables one to consider topologies on spaces of functions which have been introduced recently. A link between the Asplund and Ekeland–Lebourg methods and the Palais–Smale condition, another important topic in nonlinear analysis, is pointed out. 相似文献
92.
For symmetric spaces of noncompact type we prove an analogue of Hardy’s theorem which characterizes the heat kernel in terms
of its order of magnitude and that of its Fourier transform. 相似文献
93.
In this paper we consider the equations that govern the motion of perfect gases. We explicitly characterize some classes of steady solutions in two and three space dimensions, by introducing invertible point transformations suggested by Lie group analysis; moreover, by using various transformations known as substitution principles, new steady and unsteady solutions are constructed. 相似文献
94.
R. Rodríguez-Ramos B. E. Pobedria P. Padilla J. Bravo-Castillero R. Guinovart-Díaz G. A. Maugin 《Archive of Applied Mechanics (Ingenieur Archiv)》2004,74(3-4):191-200
Summary In the present paper, we consider the behavior of nonlinear piezoelectric materials by generalization for this case of the Hashin-Shtrikman variational principles. The new general formulation used here differs from others, because, it gives the possibility to evaluate the upper and lower Hashin-Shtrikman bounds for specific physical nonlinearities of piezoelectric materials. Geometrical nonlinearities are not considered.This work was sponsored by PAPIIT, DGAPA-UNAM IN103301. PNCB IBMFQ 09-2004 and, completed while one of the authors (RRR) was visiting the Laboratoire de Modélisation en Mécanique from Université Pierre et Marie Curie, Paris, while another one (G.A.M) benefited from the Max-Plank Award for International Cooperation (2002–2005). 相似文献
95.
96.
Deformation of single‐walled carbon nanotubes by interaction with graphene: A first‐principles study
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Xiao Wang Juan Yang Ruoming Li Hong Jiang Yan Li 《Journal of computational chemistry》2015,36(10):717-722
The interaction between single‐walled carbon nanotubes (SWNTs) and graphene were studied with first‐principles calculations. Both SWNTs and single‐layer graphene (SLG) or double‐layer graphene (DLG) display more remarkable deformations with the increase of SWNT diameter, which implies a stronger interaction between SWNTs and graphene. Besides, in DLG, deformation of the upper‐layer graphene is less than in SLG. Zigzag SWNTs show stronger interactions with SLG than armchair SWNTs, whereas the order is reversed for DLG, which can be interpreted by the mechanical properties of SWNTs and graphene. Density of states and band structures were also studied, and it was found that the interaction between a SWNT and graphene is not strong enough to bring about obvious influence on the electronic structures of SWNTs. © 2015 Wiley Periodicals, Inc. 相似文献
97.
从一般力学的二类变量的广义变分原理的角度 ,说明了一类变量的Hamilton原理的约束方程中的qε+ β具有双重含义 :第一种含义是不能仅仅通过积分约束方程求得它的解 ,即约束是非完整的 ;第二种含义是qε + β的导数必为 qε + β,即满足关系式 qε + β=ddtqε+ β.虽然上述双重含义是并存在的 ,但是 ,在某种情况下第一种含义表现得比较明显 ,在另一种情况下第二种含义表现得比较明显 .在此基础上 ,推导出Четаев条件的几种等价的表达形式 ;说明了qε+ β 的双重含义在全部代入法和Lagrange乘子法中的体现 . 相似文献
98.
The paper outlines a procedure to derive the canonical system of equations of the classical theory of thin shells using Reissner’s
variational principle and partial variational principles. The Hamiltonian form of the Reissner functional is obtained using
Lagrange multipliers to include the kinematical conditions that follow from the Kirchhoff-Love hypotheses. It is shown that
the canonical system of equations can be represented in three different forms: one conventional form (five equilibrium equations)
and two forms that are equivalent to it. This can be proved by reducing them to the same system of three equations. For problems
with separable active and passive variables, partial variational principles are formulated
__________
Translated from Prikladnaya Mekhanika, Vol. 43, No. 10, pp. 99–107, October 2007. 相似文献
99.
100.
Modeling and simulations of interface properties with first‐principles electronic structure computations
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Sanwu Wang Yingdi Liu Michael R. Halfmoon Hongli Dang Christine A. Rittenhouse Xin Liu Darwin Shields Wenhua Xue 《Mathematical Methods in the Applied Sciences》2015,38(18):4495-4501
We report extensive first‐principles electronic structure modeling and calculations for the SiC–SiO2 interface, a solid–solid interface formed during oxidation of silicon carbide (SiC). The interface modeling provides atomic‐scale understanding about the nature of the interface defects as well as passivation effects due to the modification of the interface bonding. In particular, simulation results show that incorporation of hydrogen and fluorine decreases the defect density, thus enhancing the performance of SiC‐based electronic devices. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献