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631.
Takemitsu Hasegawa 《BIT Numerical Mathematics》2001,41(5):1019-1028
A forward rounding error analysis is presented for the extended Clenshaw algorithm due to Skrzipek for evaluating the derivatives of a polynomial expanded in terms of orthogonal polynomials. Reformulating in matrix notation the three-term recurrence relation satisfied by orthogonal polynomials facilitates the estimate of the rounding error for the m-th derivative, which is recursively estimated in terms of the one for the (m – 1)-th derivative. The rounding errors in an important case of Chebyshev polynomial are discussed in some detail.This revised version was published online in October 2005 with corrections to the Cover Date. 相似文献
632.
The dynamic characteristics of a beam–cable coupled system are investigated using an improved Chebyshev spectral element method in order to observe the effects of adding cables on the beam. The system is modeled as a double Timoshenko beam system interconnected by discrete springs. Utilizing Chebyshev series expansion and meshing the system according to the locations of its connections,numerical results of the natural frequencies and mode shapes are obtained using only a few elements, and the results are validated by comparing them with the results of a finiteelement method. Then the effects of the cable parameters and layout of connections on the natural frequencies and mode shapes of a fixed-pinned beam are studied. The results show that the modes of a beam–cable coupled system can be classified into two types, beam mode and cable mode, according to the dominant deformation. To avoid undesirable vibrations of the cable, its parameters should be controlled in a reasonable range, or the layout of the connections should be optimized. 相似文献
633.
Stochastic period-doubling bifurcation analysis of stochastic Bonhoeffer--van der Pol system 总被引:2,自引:0,他引:2
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In this paper, the Chebyshev polynomial approximation is applied to
the problem of stochastic period-doubling bifurcation of a stochastic
Bonhoeffer--van der Pol (BVP for short) system with a bounded random
parameter. In the analysis, the stochastic BVP system is transformed
by the Chebyshev polynomial approximation into an equivalent
deterministic system, whose response can be readily obtained by
conventional numerical methods. In this way we have explored plenty
of stochastic period-doubling bifurcation phenomena of the stochastic
BVP system. The numerical simulations show that the behaviour of the
stochastic period-doubling bifurcation in the stochastic BVP system
is by and large similar to that in the deterministic mean-parameter
BVP system, but there are still some featured differences between
them. For example, in the stochastic dynamic system the
period-doubling bifurcation point diffuses into a critical interval
and the location of the critical interval shifts with the variation
of intensity of the random parameter. The obtained results show that
Chebyshev polynomial approximation is an effective approach to
dynamical problems in some typical nonlinear systems with a bounded
random parameter of an arch-like probability density function. 相似文献
634.
635.
Two algorithms for the solution of a parametric optimal design problem are developed and applied to example problems from diverse fields, such as finite allocation problems, optimal design of dynamical systems, and Chebyshev approximation. Sensitivity analysis gives rise to a first-order feedback law, which contains a compensating term for any error in the nominal solution, as well as sensitivity of the solution with respect to design parameters. The compensating term, when used alone, leads to a new second-order method of maximization for a linearly-constrained nonlinear programming problem.This paper is based on the PhD Thesis of the first author. 相似文献
636.
637.
One of the considerable discussions in data interpolation is to find the optimal number of data which minimizes the error of the interpolation polynomial. In this paper, first the theorems corresponding to the equidistant nodes and the roots of the Chebyshev polynomials are proved in order to estimate the accuracy of the interpolation polynomial, when the number of data increases. Based on these theorems, then we show that by using a perturbation method based on the CESTAC method, it is possible to find the optimal degree of the interpolation polynomial. The results of numerical experiments are presented. 相似文献
638.
Recent advances in the collection of Lagrangian data from the ocean and results about the well-posedness of the primitive equations have led to a renewed interest in solving flow equations in Lagrangian coordinates. We do not take the view that solving in Lagrangian coordinates equates to solving on a moving grid that can become twisted or distorted. Rather, the grid in Lagrangian coordinates represents the initial position of particles, and it does not change with time. We apply numerical methods traditionally used to solve differential equations in Eulerian coordinates, to solve the shallow water equations in Lagrangian coordinates. The difficulty with solving in Lagrangian coordinates is that the transformation from Eulerian coordinates results in solving a highly nonlinear partial differential equation. The non-linearity is mainly due to the Jacobian of the coordinate transformation, which is a precise record of how the particles are rotated and stretched. The inverse Jacobian must be calculated, thus Lagrangian coordinates cannot be used in instances where the Jacobian vanishes. For linear (spatial) flows we give an explicit formula for the Jacobian and describe the two situations where the Lagrangian shallow water equations cannot be used because either the Jacobian vanishes or the shallow water assumption is violated. We also prove that linear (in space) steady state solutions of the Lagrangian shallow water equations have Jacobian equal to one. In the situations where the shallow water equations can be solved in Lagrangian coordinates, accurate numerical solutions are found with finite differences, the Chebyshev pseudospectral method, and the fourth order Runge–Kutta method. The numerical results shown here emphasize the need for high order temporal approximations for long time integrations. 相似文献
639.
The numerical solution of elliptic selfadjoint second-order boundary value problems leads to a class of linear systems of equations with symmetric, positive definite, large and sparse matrices which can be solved iteratively using a preconditioned version of some algorithm. Such differential equations originate from various applications such as heat conducting and electromagnetics. Systems of equations of similar type can also arise in the finite element analysis of structures. We discuss a recursive method constructing preconditioners to a symmetric, positive definite matrix. An algebraic multilevel technique based on partitioning of the matrix in two by two matrix block form, approximating some of these by other matrices with more simple sparsity structure and using the corresponding Schur complement as a matrix on the lower level, is considered. The quality of the preconditioners is improved by special matrix polynomials which recursively connect the preconditioners on every two adjoining levels. Upper and lower bounds for the degree of the polynomials are derived as conditions for a computational complexity of optimal order for each level and for an optimal rate of convergence, respectively. The method is an extended and more accurate algebraic formulation of a method for nine-point and mixed five- and nine-point difference matrices, presented in some previous papers. 相似文献
640.
Intuitively, one might consider an affinely regular polygon of the Eucidean plane to be the result of applying an affine transformation to a regular polygon. These affinely regular polygons, and their kindred that go by the same name in the Euclidean plane as well as in more general affine planes, have been onjects of investigations at all levels of sophistication and in a remarkable variety of contexts. For example, they arise in linear algebra as a set of vectors that are cyclically permuted by a unimodular matrix. Our purpose is to describe this concept and its attributes in a general setting. The main result is Theorem 1 where we present seven equivalent definitions of affine regularity, one of which appears for the first time. We are careful to distinguish these definitions from the weaker intuitive definition. Our work also features an application of Chebyshev polynomials to describe parameters associated with these polygons. 相似文献