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991.
H. W. Broer I. Hoveijn M. van Noort C. Simó G. Vegter 《Journal of Dynamics and Differential Equations》2004,16(4):897-947
This paper is concerned with the global coherent (i.e., non-chaotic) dynamics of the parametrically forced pendulum. The system is studied in a === degree of freedom Hamiltonian setting with two parameters, where a spatio-temporal symmetry is taken into account. Our explorations are restricted to large regions of coherent dynamics in phase space and parameter plane. At any given parameter point we restrict to a bounded subset of phase space, using KAM theory to exclude an infinitely large region with rather trivial dynamics. In the absence of forcing the system is integrable. Analytical and numerical methods are used to study the dynamics in a parameter region away from integrability, where the analytic results of a perturbation analysis of the nearly integrable case are used as a starting point. We organize the dynamics by dividing the parameter plane in fundamental domains, guided by the linearized system at the upper and lower equilibria. Away from integrability some features of the nearly integrable coherent dynamics persist, while new bifurcations arise. On the other hand, the chaotic region increases.2000 Mathematical Subject Classification: 37J20, 37J40, 37M20, 70H08.Dedicated to Professor Shui-Nee Chow on the occasion of his 60th birthday. 相似文献
992.
The formulism of a two-equation model for heat conduction in porous media, developed in a previous paper, is applied to the case of steady state one-dimensional heat transfer in a porous medium that is made up of geometrically similar units of similar size and of ordered spatial distribution. For this case study, the model-predicted locally volume-averaged temperature distributions for the solid and the fluid phase are compared to a numerical solution at a microscopic level, showing excellent agreement. 相似文献
993.
HT-7U托克马克装置的纵场线圈是由多种材料组成的具有周期性分布的大型复杂结构,线圈可视为由超导线、支撑结构和绝缘材料组成的复合材料,结构极其复杂。整个线圈工作在液氦温区。在设计阶段对其宏观等效力学性能进行数值分析计算是十分必要的,但要对整个线圈直接进行有限元分析或实验是极其困难的,主要利用均匀化方法对其进行等效处理,从而分析计算其宏观等效模量,为线圈的设计和评估提供参考依据。另外本文对均匀化方法的边界条件进行了一些改进,提出了更加合理的三维边界条件。 相似文献
994.
995.
提出了一种超声无触点支承方案,详细介绍了超声无触点支承原理。通过对声辐射理论的研究,获得超声无触点支承的理论依据。实验证明实现这种超声波无触点支承是可行的。根据这一理论,对三轴无触点支承结构进行了选择设计。 相似文献
996.
杨守志 《应用数学和力学(英文版)》2006,27(12):1687-1695
Poly-scale refinable function with dilation factor a is introduced. The existence of solution of poly-scale refinable equation is investigated. Specially, necessary and sufficient conditions for the orthonormality of solution functionφof poly-scale refinable equation with integer dilation factor a are established. Some properties of poly-scale re-finable function are discussed. Several examples illustrating how to use the method to construct poly-scale refinable function are given. 相似文献
997.
By using the Z
p
geometrical index theory, some sufficient conditions on the multiplicity results of periodic solutions to the second-order difference equations
are obtained. By two examples, we show that our results are the best possible in the sense that the lower bound of the number of periodic solutions cannot be improved. 相似文献
998.
Wei Tong 《Experimental Mechanics》2004,44(5):502-511
A technique using a single CCD camera, a precision rotation/translation stage, a telecentric zoom lens, and digital image
correlation software is described for measuring surface profiles and surface plastic strain distributions of a bent thin sheet.
The measurement principles, based on both parallel and pinhole perspective projections, are outlined and the relevant mathematical
equations for computing the profiles and displacement fields on a curved surface are presented. The typical optical setup
as well as the experimental measurement and digital image correlation analysis procedure are described. The maximum errors
in the in-plane and out-of-plane coordinates or displacements are about ±5 and ±25 μm, respectively, and the maximum errors
in surface strain mapping are about 0.1% or less based on a series of evaluation tests on flat and curved sample surfaces
over a physical field of view of 15.2 × 11.4 mm2. As an application example, the shape and surface plastic strain distribution example, the shape and surface plastic strain
distributions around a bent apex of a flat 2 mm thick automotive aluminum AA5182-O sheet, which underwent a 90° bend with
three bend ratios of 2t, 1t, and 0.6t, are determined using the proposed technique. 相似文献
999.
1000.
本文提出的采用增量理论的分析模型和方法可以定量分析应变硬化、包辛格效应和材料机械性质随温度变化等因素对自增强厚壁圆筒中残余应力和操作应力分布的影响.厚壁圆筒看成由N个同轴薄壁圆筒套在一起组成的构件;采用包括弹性、塑性和温度应变的增量型本构关系和相容条件导出了自增强圆筒的基本方程;设计了计算机程序并给出了分析实例。分析结果表明,应变硬化会减小塑性区并降低残余应力;包辛格效应使反向屈服容易出现;温度升高将使残余应力和热应力松驰. 相似文献