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《Finite Elements in Analysis and Design》2009,45(1):60-69
The way the non-linear constitutive equations in the spatial beam formulations are solved, influences the rate of convergence and the computational cost. Three different approaches are studied: (i) the direct global approach, where the constitutive equations are taken to be the iterative part of the global governing equations, (ii) the local (or indirect global) approach, where the constitutive equations are solved separately in each step of the global iteration, and (iii) the partly reduced approach, which is the combination of (i) and (ii). The approaches are compared with regard to the number of global iterations and the total number of floating point operations. The direct global approach is found to be the best choice. 相似文献
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以地球大气变暖海平面升高为背景,对近几十年CO2排放量上升引起气温升高,气温升高引起海平面上升分别建立了数学模型,同时针对美国佛罗里达州的气候状况进行分析,预测几十年后的海平面上升对大陆面积的影响. 相似文献
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In this paper, a general class of impulsive delayed switched systems is considered. By employing the Lyapunov–Razumikhin method and some analysis techniques, we established several global asymptotic stability and global exponential stability criteria for the considered impulsive delayed switched systems, which improve and extend some recent works. As an application, the result of global exponential stability are used to study a class of uncertain linear switched systems with time‐varying delays. Several LMI‐based conditions are proposed to guarantee the global robust stability and global exponential stabilization. The designed memoryless state feedback controller can be easily checked by the LMI toolbox in Matlab. Moreover, the dwell time constraint is imposed for the switching law. Finally, two numerical examples and their simulations are given to show the effectiveness of our proposed results. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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Let A be a(left and right) Noetherian ring that is semiperfect. Let e be an idempotent of A and consider the ring Γ :=(1-e)A(1-e) and the semi-simple right A-module Se := e A/e rad A. In this paper, we investigate the relationship between the global dimensions of A and Γ, by using the homological properties of Se. More precisely, we consider the Yoneda ring Y(e) := Ext_A~*(Se, Se) of e. We prove that if Y(e) is Artinian of finite global dimension, then A has finite global dimension if and only if so does Γ. We also investigate the situation where both A and Γ have finite global dimension. When A is Koszul and finite dimensional, this implies that Y(e) has finite global dimension. We end the paper with a reduction technique to compute the Cartan determinant of Artin algebras. We prove that if Y(e) has finite global dimension, then the Cartan determinants of A and Γ coincide. This provides a new way to approach the long-standing Cartan determinant conjecture. 相似文献
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In this paper, the Bayesian methods of global optimization are considered. They provide the minimal expected deviation from the global minimum. It is shown that, using the Bayesian methods, the asymptotic density of calculations of the objective function is much greater around the point of global minimum. The relation of this density to the parameters of the method and to the function is defined.Algorithms are described which apply the Bayesian methods to problems with linear and nonlinear constraints. The Bayesian approach to global multiobjective optimization is defined. Interactive procedures and reduction of multidimensional data in the case of global optimization are discussed. 相似文献
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首先研究高阶线性差分方程的整体收敛性,并证明了高阶非线性差分方程各阶导数的整体收敛;进而得到了关于高阶非线性差分方程整体收敛的一个定理,最后利用这个定理部分解决了Ladas提出的一个猜测。 相似文献
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In this paper, we present necessary as well as sufficient conditions for a given feasible point to be a global minimizer of
the difference of quadratic and convex functions subject to bounds on the variables. We show that the necessary conditions
become necessary and sufficient for global minimizers in the case of a weighted sum of squares minimization problems. We obtain
sufficient conditions for global optimality by first constructing quadratic underestimators and then by characterizing global
minimizers of the underestimators. We also derive global optimality conditions for the minimization of the difference of quadratic
and convex functions over binary constraints. We discuss several numerical examples to illustrate the significance of the
optimality conditions.
The authors are grateful to the referees for their helpful comments and valuable suggestions which have contributed to the
final preparation of the paper. 相似文献
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We develop the inheritance principle for local properties by the global Poincare mapping of nonautonomous dynamical systems. Namely, if a semigroup property is uniformly locally universal then it is enjoyed by the global Poincare mapping. In studying the global dynamics of competitors in a periodic medium, the crucial role is played by the multiplicative semigroup of the so-called sign-invariant matrices. We give geometric criteria for stability of equilibria (periodic solutions) in competition models. 相似文献
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微分方程光滑线性化的研究,目前仅限于原点近傍的小邻域,本文给出了一个全局光滑线性化的结论.全局拓扑线性化或全局光滑线性化的先决条件是任一解的存在区间为全实轴.因此,本文也讨论了Wintner定理的推广问题. 相似文献