Precise integration methods based on the Chebyshev polynomial of the first kind

This paper introduces two new types of precise integration methods based on Chebyshev polynomial of the first kind for dynamic response analysis of structures, namely the integral formula method （IFM） and the homogenized initial system method （HISM）. In both methods, nonlinear variable loadings within time intervals are simulated using Chebyshev polynomials of the first kind before a direct integration is performed. Developed on the basis of the integral formula, the recurrence relationship of the integral computation suggested in this paper is combined with the Crout decomposed method to solve linear algebraic equations. In this way, the IFM based on Chebyshev polynomial of the first kind is constructed. Transforming the non-homogenous initial system to the homogeneous dynamic system, and developing a special scheme without dimensional expansion, the HISM based on Chebyshev polynomial of the first kind is able to avoid the matrix inversion operation. The accuracy of the time integration schemes is examined and compared with other commonly used schemes, and it is shown that a greater accuracy as well as less time consuming can be achieved. Two numerical examples are presented to demonstrate the applicability of these new methods.

A Method for Solving Fredholm Integral Equations of the First Kind Based on Chebyshev Wavelets

In this paper, we suggest a method for solving Fredholm integral equation of the first kind based on wavelet basis. The continuous Legendre and Chebyshev wavelets of the first, second, third and fourth kind on [0,1] are used and are utilized as a basis in Galerkin method to approximate the solution of integral equations. Then, in some examples the mentioned wavelets are compared with each other.

Multilevel Iteration Methods for Solving Linear Operator Equations of the First Kind

In this paper we develop two multilevel iteration methods for solving linear systems resulting from the Galerkin method and Tikhonov regularization for linear ill-posed problems. The two algorithms and their convergence analyses are presented in an abstract framework.

ON THE REGULARIZATION METHOD OF THE FIRST KIND OFFREDHOLM INTEGRAL EQUATION WITH A COMPLEX KERNEL AND ITS APPLICATION

The regularized integrodifferential equation for the first kind of Fredholm, integral equation with a complex kernel is derived by generalizing the Tikhonov regularization method and the convergence of approximate regularized solutions is discussed. As an application of the method, an inverse problem in the two-dimensional wave-making problem of a flat plate is solved numerically, and a practical approach of choosing optimal regularization parameter is given.

ABSOLUTE MONOTONICITY INVOLVING THE COMPLETE ELLIPTIC INTEGRALS OF THE FIRST KIND WITH APPLICATIONS

Let K(r)be the complete elliptic integrals of the first kind for r∈(0,1)and f_(p)(x)=[(1−x)^(p)K(√x)].Using the recurrence method,we find the necessary and sufficient conditions for the functions−f′_(p),ln f_(p),−(ln f_(p))^((i))(i=1,2,3)to be absolutely monotonic on(0,1).As applications,we establish some new bounds for the ratios and the product of two complete integrals of the first kind,including the double inequalities exp[r^(2)(1−r^(2))/^(64)]/(1+r)^(1/4)<K(r)/K(√r)<exp[−r(1−r)/4],π/2 exp[θ0(1−2r^(2))]<π/2 K(r′)/K(r)<π/2(r′/r)^(p)exp[θ_(p)(1−2r^(2))],K^(2)(1/√2)≤K(r)K(r′)≤1/√2rr′K^(2)(1/√2)for r∈2(0,1)and p≥13/32,where r′=√1−r^(2) and θ_(p)=2Γ(3/4)^(4)/π^(2)−p.

Determinantal Expressions and Recursive Relations for the Bessel Zeta Function and for a Sequence Originating from a Series Expansion of the Power of Modified Bessel Function of the First Kind

In the paper,by virtue of a general formula for any derivative of the ratio of two differentiable functions,with the aid of a recursive property of the Hessenberg determinants,the authors establish determinantal expressions and recursive relations for the Bessel zeta function and for a sequence originating from a series expansion of the power of modified Bessel function of the first kind.

A Principal Theorem of Normal Discretization Schemes for Operator Equations of the First Kind

The authors announce a newly-proved theorem of theirs. This theorem is of principal significance to numerical computation of operator equations of the first kind.

EXTRAPOLATION FOR COLLOCATION METHOD OF THE FIRST KIND VOLTERRA INTEGRAL EQUATIONS

1. Introduction It is known that the following Cauchy problem for a parabolic partial differential equation (where the values at the right boundary, u.(1, t)=v(t) are unknown and sought for) is ill-posed: the solution (v) does not depend continuously on the data (g). In order to treat the ill-posedness and develop the numerical method, one reformulates the problem as a Volterra integral equation of the first kind wish a convolution type kernel (see Sneddon [1], Carslaw and Jaeger [2])

Integral Operator Solving Process of the Boundary Value Problem of Abstract Kinetic Equation with the First Kind of Critical Parameter and Generalized Periodic Boundary Conditions

在这份报纸，边界的概念与第一种批评参数珍视抽象运动方程的问题 0 并且概括周期的边界条件在由函数组成，向量在一个一般 Banach 空格珍视的一个 Lebesgue 空格被介绍，然后描述这些的解决方案由 Volterra 的抽象线性不可分的操作符的抽象边界值问题类型。我们把这个过程称为解决过程的不可分的操作员。

DIRECT IMPLEMENTATION OF TIKHONOV REGULARIZATION FOR THE FIRST KIND INTEGRAL EQUATION

A common way to handle the Tikhonov regularization method for the first kind Fredholm integral equations,is first to discretize and then to work with the final linear system.This unavoidably inflicts discretization errors which may lead to disastrous results,especially when a quadrature rule is used.We propose to regularize directly the integral equation resulting in a continuous Tikhonov problem.The Tikhonov problem is reduced to a simple least squares problem by applying the Golub-Kahan bidiagonalization(GKB)directly to the integral operator.The regularization parameter and the iteration index are determined by the discrepancy principle approach.Moreover,we study the discrete version of the proposed method resulted from numerical evaluating the needed integrals.Focusing on the nodal values of the solution results in a weighted version of GKB-Tikhonov method for linear systems arisen from the Nystr¨om discretization.Finally,we use numerical experiments on a few test problems to illustrate the performance of our algorithms.

The Collocation Method and the Splitting Extrapolation for the First Kind of Boundary Integral Equations on Polygonal Regions

In this paper,the collocation methods are used to solve the boundary integral equations of the first kind on the polygon.By means of Sidi’s periodic transformation and domain decomposition,the errors are proved to possess the multi-parameter asymptotic expansion at the interior point with the powers h^(3)/_(i)(i=1,...,d),which means that the approximations of higher accuracy and a posteriori estimation of the errors can be obtained by splitting extrapolations.Numerical experiments are carried out to show that the methods are very efficient.

Finite-order inner automorphisms of the first kind on affine Lie algebras

SOME authors classified order two and order three automorphisms of affine Lie algebras. In this letter,

Functions on discrete sets holomorphic in the sense of Isaacs, or monodiffric functions of the first kind

We study discrete analogues of holomorphic functions of one and two variables, especially those that were called monodiffric functions of the first kind by Rufus Isaacs. Discrete analogues of the Cauchy-Riemann operators, domains of holomorphy in one discrete variable, and the Hartogs phenomenon in two discrete variables are investigated.

Identities for degenerate Bernoulli polynomials and Korobov polynomials of the first kind

In this paper, we derive five basic identities for Sheffer polynomials by using generalized Pascal functional and Wronskian matrices. Then we apply twelve basic identities for Sheffer polynomials, seven from previous results, to degenerate Bernoulli polynomials and Korobov polynomials of the first kind and get some new identities. In addition, letting λ→ 0 in such identities gives us those for Bernoulli polynomials and Bernoulli polynomials of the second kind.

基于切向量的两类曲线积分的关系

利用极限的定义作为基本方法,按照参数增加和减少两种情况,再统筹曲线的方向分为四种具体情况分别证明了有向曲线的切向量的表达式,并且得到了不同情况下的两类曲线积分之间的关系,最后通过举例说明了结论的正确性.

Convergence Phenomenon with Fourier Series of tg(x2)and Alike

The Fourier series of the 2π-periodic functions tg(x2)and 1sin(x)and some of their relatives (first of their integrals) are investigated and illustrated with respect to their convergence. These functions are Generalized functions and the convergence is weak convergence in the sense of the convergence of continuous linear functionals defining them. The figures show that the approximations of the Fourier series possess oscillations around the function which they represent in a broad band embedding them. This is some analogue to the Gibbs phenomenon. A modification of Fourier series by expansion in powers cosn(x)for the symmetric part of functions and sin(x)cosn−1(x)for the antisymmetric part (analogous to Taylor series) is discussed and illustrated by examples. The Fourier series and their convergence behavior are illustrated also for some 2π-periodic delta-function-like sequences connected with the Poisson theorem showing non-vanishing oscillations around the singularities similar to the Gibbs phenomenon in the neighborhood of discontinuities of functions. .

用无穷矩阵方程求解第二类Stirling数表示的自然数幂和

讨论了4个用第二类Stirling数表示的自然数的幂和公式.利用升阶乘和降阶乘的定义式,得到关于各阶幂和的递推关系,用求解无穷矩阵方程的方法给出用第二类Stirling数表示的幂和公式,并证明了它们之间的等价性.

利用积分的轮换对称性巧解数学竞赛题

针对第十三届(2021年)全国大学生数学竞赛第四大题,利用积分的轮换对称性,给出了一种巧妙解法,简单直接.

基于CFD/CSD弱耦合方法的后掠尖旋翼气弹响应分析

准确计算旋翼的气弹响应,对于旋翼的设计与振动控制具有重要的意义。传统的旋翼气动模型通常采用简单的叶素理论、自由尾迹方法,导致气动力计算精度较差。这里的CFD计算采用非定常重叠动网格计算方法,通过直接求解Navier-Stokes方程的方法获得尾迹,旋翼的流场网格采用多重动网格方法生成。CSD计算采用有限体积梁单元建立桨叶的有限体积梁模型,边界条件采用第一类拉格朗日乘子法进行考虑。流固耦合交界面的气动力计算结果通过插值和积分映射到CSD模型上,在此基础上进行旋翼的气弹响应分析。

从朱丹溪“六郁”学说探讨中风病因病机

朱丹溪基于《黄帝内经》“五郁”理论,首创“气、湿、痰、热、血、食”之“六郁”学说,提出“人身诸病,多生于郁”“气郁为六郁之先”“凡郁皆在中焦”等观点。笔者通过系统梳理“六郁”学说,提出中风病因病机与“六郁”密切相关。指出六郁皆为中风常见病理因素,气郁为先,诸郁相合,损伤营卫气血津液进而累及血脉,损脑毁神,与中风气机逆乱、病在血脉、脑髓神机受损的病机特点高度契合,故六郁能完满解释临床所观察到的各项危险因素导致中风的发病机制。将“六郁”学说与血脉理论相结合,指导中风病因病机认识,以此为理论基础干预诸郁形成与致病过程,是保护血脉、预防中风的有效方法。