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81.
ZHAO Wei-Qin 《理论物理通讯》2004,42(7)
A revised iterative method based on Green function defined by quadratures along a single trajectory is proposed to solve the low-lying quantum wave function for Schrodinger equation. Specially a new expression of the perturbed energy is obtained, which is much simpler than the traditional one. The method is applied to solve the unharmonic oscillator potential. The revised iteration procedure gives exactly the same result as those based on the single trajectory quadrature method. A comparison of the revised iteration method to the old one is made using the example of Stark effect. The obtained results are consistent to each other after making power expansion. 相似文献
82.
We study the dynamical behavior of the discontinuous Galerkin finite element method for initial value problems in ordinary differential equations. We make two different assumptions which guarantee that the continuous problem defines a dissipative dynamical system. We show that, under certain conditions, the discontinuous Galerkin approximation also defines a dissipative dynamical system and we study the approximation properties of the associated discrete dynamical system. We also study the behavior of difference schemes obtained by applying a quadrature formula to the integrals defining the discontinuous Galerkin approximation and construct two kinds of discrete finite element approximations that share the dissipativity properties of the original method.
83.
等截面梁有限变形的传递函数增量算法 总被引:1,自引:1,他引:1
本文介绍了一种计算等截面梁有限变形的新方法-传递函数增量算法,它是一种半解析数值计算方法。此算法充分利用增量失空法Gauss求积公式计算非线性有限变形的特点,并将这些特点与传递函数方法,有效地结合起来,既避免了数值方法计算量大的困难,又使得求解高阶非线性微分方程的解析解成为可能,算例分析表明,这是一种易编程,计算量小,收敛快,求解精度高的行之有效的计算方法。 相似文献
84.
Marco Bee Giuseppe Espa Diego Giuliani Flavio Santi 《Journal of computational and graphical statistics》2017,26(3):695-708
In this article, we use the cross-entropy method for noisy optimization for fitting generalized linear multilevel models through maximum likelihood. We propose specifications of the instrumental distributions for positive and bounded parameters that improve the computational performance. We also introduce a new stopping criterion, which has the advantage of being problem-independent. In a second step we find, by means of extensive Monte Carlo experiments, the most suitable values of the input parameters of the algorithm. Finally, we compare the method to the benchmark estimation technique based on numerical integration. The cross-entropy approach turns out to be preferable from both the statistical and the computational point of view. In the last part of the article, the method is used to model the probability of firm exits in the healthcare industry in Italy. Supplemental materials are available online. 相似文献
85.
Hassan Khosravian‐Arab Mehdi Dehghan M. R. Eslahchi 《Mathematical Methods in the Applied Sciences》2017,40(18):6389-6410
This paper presents 2 new classes of the Bessel functions on a compact domain [0,T] as generalized‐tempered Bessel functions of the first‐ and second‐kind which are denoted by GTBFs‐1 and GTBFs‐2. Two special cases corresponding to the GTBFs‐1 and GTBFs‐2 are considered. We first prove that these functions are as the solutions of 2 linear differential operators and then show that these operators are self‐adjoint on suitable domains. Some interesting properties of these sets of functions such as orthogonality, completeness, fractional derivatives and integrals, recursive relations, asymptotic formulas, and so on are proved in detail. Finally, these functions are performed to approximate some functions and also to solve 3 practical differential equations of fractionalorders. 相似文献
86.
高速移动荷载下黏弹性半空间体的动力响应 总被引:2,自引:0,他引:2
分别以移动荷载和黏弹性半空间体模拟运动列车荷载和地基,分析了地基在运动列车作用下的动力响应.首先采用Green函数法求解黏弹性半空间体在各种移动荷载模式作用下的动力响应的解析解,包括恒常和简谐移动点源、线源和面源荷载.然后采用IFFT算法和自适应数值积分算法计算解析解中的二维积分,得到了包括低音速、跨音速和超音速移动荷载作用下位移的数值结果.最后分析了速度对位移的分布和最大值的影响,发现当速度大于Rayleigh波速时,位移发生显著变化. 相似文献
87.
88.
The evaluation of matrix functions of the form f(A)v, where A is a large sparse or structured symmetric matrix, f is a nonlinear function, and v is a vector, is frequently subdivided into two steps: first an orthonormal basis of an extended Krylov subspace of fairly small dimension is determined, and then a projection onto this subspace is evaluated by a method designed for small problems. This paper derives short recursion relations for orthonormal bases of extended Krylov subspaces of the type Km,mi+1(A)=span{A-m+1v,…,A-1v,v,Av,…,Amiv}, m=1,2,3,…, with i a positive integer, and describes applications to the evaluation of matrix functions and the computation of rational Gauss quadrature rules. 相似文献
89.
M.M. Panja 《Applied mathematics and computation》2011,218(8):4147-4151
This note is concerned with an efficient computation of integrals of products of a smooth function and Daubechies scale function with partial support by using a one-point quadrature rule. The error estimate is obtained. The rule is illustrated by considering an example from the literature. 相似文献
90.
The hydrocarbon plus fractions that comprise a significant portion of naturally occurring hydrocarbon fluids create major problems when determining the thermodynamic properties and the volumetric behavior of these fluids by equations of state. These problems arise due to the difficulty of properly characterizing the plus fractions (heavy ends). Proper characterization of the heavier components is important when cubic equations of state and/or solid formation thermodynamic models are used to describe complex phase behavior of reservoir fluids. The effect of heavy fractions characterization on thermodynamic modeling of wax precipitation has been investigated using different models including Won, Pan and proposed models. In order to characterize the plus fraction (heavier part) as a series of pseudocomponents, a probability model that expresses the mole fraction as a continuous function of the molecular weight has been used. The study has been conducted using several mixtures. Two different SCN (single carbon number), C7+ and C10+ were chosen. The Chosen SCN were distributed to multi-components of five, six, and/or ten using continuous function and Gaussian quadrature method. The results showed that the fractioning is required to be able to predict wax precipitation. Distribution of C10+ using a proper distribution function has shown improvement in predictions of WAT and the amount of wax deposited in comparison with the characterization of C7+ using semi-continuous approach. In predicting of WAT and the amount of wax build up the developed model showed superiority over the others. 相似文献