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引入辅助未知函数及辅助未知函数的积分关系式,表示原未知函数,将对偶积分方程组退耦.应用Sonine第一有限积分公式,实现化为Abel型积分方程组,应用Abel反演变换并化简,正则化为含对数核的第一类Fredholm奇异积分方程组.由此给出奇异积分方程组的一般性解,进而获得对偶积分方程组的解析解,同时严格地证明了,对偶积分方程组和由它化成的含对数核的奇异积分方程组的等价性,以及对偶积分方程组解的存在性和唯一性. 相似文献
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分析了二维问题边界元法3节点二次单元的几何特征,区分和定义了源点相对高阶单元的Ⅰ型和Ⅱ型接近度.针对二维位势问题高阶边界元中奇异积分核,构造出具有相同Ⅱ型几乎奇异性的近似核函数,在几乎奇异积分单元上分离出积分核中主导的奇异函数部分.原积分核扣除其近似核函数后消除几乎奇异性,成为正则积分核函数,并采用常规Gauss数值方法计算该正则积分;对奇异核函数的积分推导出解析公式,从而建立了一种新的边界元法高阶单元几乎奇异积分半解析算法.应用该算法计算了二维薄体结构温度场算例,计算结果表明高阶单元半解析算法能充分发挥边界元法优势,显著提高计算精度. 相似文献
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根据向量值全纯函数和亚纯函数的理论,由向量值Plemelj公式,讨论一类局部凸空间中具有ζ-函数核的奇异积分方程与边值问题的关系,给出向量值奇异积分方程和边值问题的解及其稳定性. 相似文献
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利用复变函数方法和积分方程理论研究了既含有圆形孔口又含有水平裂纹的无限大平面的平面弹性问题,将复杂的解析函数的边值问题化成了求解只在裂纹上的奇异积分方程的问题.此外,还给出了裂纹尖端附近的应力场和应力强度因子的公式. 相似文献
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研究了Clifford分析中弱奇异积分算子和以弱奇异积分算子的奇点为积分变量的带参量的Cauchy型奇异积分算子在Liapunov闭曲面上的换序问题.首先证明了相关的奇异积分的性质,并利用这些性质证明了两个累次积分是有意义的,然后将积分区域分为几部分,从而将积分算子分为带有奇性的部分和不带奇性的部分.证明了带有奇性的部分的极限是零,不带奇性的部分相等.这样就证明了弱奇异积分算子和以弱奇异积分算子的奇点为积分变量的Clifford分析中超正则函数的拟Cauchy型奇异积分算子的换序公式. 相似文献
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Cn中双球相交域上具有全纯核的奇异积分的Sokhotsky-Plemelj公式具有一种特殊的形式,它在边界上是分片连续的.利用这个Sokhotsky-Plemelj公式,在适当条件下得到了一个特殊的合成公式,并得到了常系数奇异积分方程和方程组的特征方程一个直接解,并把常系数奇异积分方程和方程组化为一类与之等价的Fred... 相似文献
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实Clifford分析中三类高阶奇异积分及其非线性微分积分方程 总被引:9,自引:0,他引:9
本文第一部分借助于高阶异积分的Hadamard主值的思想以及归纳法的思想,在证明了6个引理的基础上讨论实Clifford分析中三类高阶异积分的归纳定义,Hadamard主值的存在性,递推公式,计算公式以及高阶奇异积分在Hadamard主值意义下的12个微分公式,受多复变中解析函数积分表示式多样笥的,本文采用的算子的积分表达式就与个公式和微分公式都十分乘法本文第二部分在引进并证明了Hile引理型的基 相似文献
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超奇异积分的数值计算是边界元方法中的重要的课题之一,本文得到了牛顿科茨公式计算任意阶超奇异积分误差估计,当误筹函数中的Sκ(p)(Τ)=0时,便得到超收敛现象,并给出了Sκ(p)(Τ)之间的相互关系.相应的数值算例验证了理论分析的正确性. 相似文献
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Frank MüllerWerner Varnhorn 《Applied mathematics and computation》2011,217(13):6409-6416
In this article a method is presented, which can be used for the numerical treatment of integral equations. Considered is the Fredholm integral equation of second kind with continuous kernel, since this type of integral equation appears in many applications, for example when treating potential problems with integral equation methods.The method is based on the approximation of the integral operator by quasi-interpolating the density function using Gaussian kernels. We show that the approximation of the integral equation, gained with this method, for an appropriate choice of a certain parameter leads to the same numerical results as Nyström’s method with the trapezoidal rule. For this, a convergence analysis is carried out. 相似文献
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We develop a fourth-order piecewise quartic spline rule for Hadamard
integral. The quadrature formula of Hadamard integral is obtained by replacing
the integrand function with the piecewise quartic spline interpolation function. We
establish corresponding error estimates and analyze the numerical stability. The
rule can achieve fourth-order convergence at any point in the interval, even when
the singular point coincides with the grid point. Since the derivative information of
the integrand is not required, the rule can be easily applied to solve many practical
problems. Finally, the quadrature formula is applied to solve the electromagnetic
scattering from cavities with different wave numbers, which improves the whole
accuracy of the solution. Numerical experiments are presented to show the efficiency
and accuracy of the theoretical analysis. 相似文献
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Xin Wen 《计算数学(英文版)》2011,29(3):305-323
In this paper we design and analyze a class of high order numerical methods to two dimensional Heaviside function integrals. Inspired by our high order numerical methods to two dimensional delta function integrals [19], the methods comprise approximating the mesh cell restrictions of the Heaviside function integral. In each mesh cell the two dimensional Heaviside function integral can be rewritten as a one dimensional ordinary integral with the integrand being a one dimensional Heaviside function integral which is smooth on several subsets of the integral interval. Thus the two dimensional Heaviside function integral is approximated by applying standard one dimensional high order numerical quadratures and high order numerical methods to one dimensional Heaviside function integrals. We establish error estimates for the method which show that the method can achieve any desired accuracy by assigning the corresponding accuracy to the sub-algorithms. Numerical examples are presented showing that the second- to fourth-order methods implemented in this paper achieve or exceed the expected accuracy. 相似文献
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In this paper, the weakly singular Volterra integral equations with an infinite set of solutions are investigated. Among the set of solutions only one particular solution is smooth and all others are singular at the origin. The numerical solutions of this class of equations have been a difficult topic to analyze and have received much previous investigation. The aim of this paper is to present a numerical technique for giving the approximate solution to the only smooth solution based on reproducing kernel theory. Applying weighted integral, we provide a new definition for reproducing kernel space and obtain reproducing kernel function. Using the good properties of reproducing kernel function, the only smooth solution is exactly expressed in the form of series. The n-term approximate solution is obtained by truncating the series. Meanwhile, we prove that the derivative of approximation converges to the derivative of exact solution uniformly. The final numerical examples compared with other methods show that the method is efficient. 相似文献
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Meisam Jozi & Saeed Karimi 《计算数学(英文版)》2022,40(3):335-353
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 Nyström discretization. Finally, we use numerical experiments on a few test problems to illustrate the performance of our algorithms. 相似文献
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Amjad Alipanah Shahrokh Esmaeili 《Journal of Computational and Applied Mathematics》2011,235(18):5342-5347
In this paper, we introduce a numerical method for the solution of two-dimensional Fredholm integral equations. The method is based on interpolation by Gaussian radial basis function based on Legendre-Gauss-Lobatto nodes and weights. Numerical examples are presented and results are compared with the analytical solution to demonstrate the validity and applicability of the method. 相似文献
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Pouria Assari 《Applicable analysis》2013,92(11):2064-2084
The present work proposes a numerical method to obtain an approximate solution of non-linear weakly singular Fredholm integral equations. The discrete Galerkin method in addition to thin-plate splines established on scattered points is utilized to estimate the solution of these integral equations. The thin-plate splines can be regarded as a type of free shape parameter radial basis functions which create an efficient and stable technique to approximate a function. The discrete Galerkin method for the approximate solution of integral equations results from the numerical integration of all integrals in the method. We utilize a special accurate quadrature formula via the non-uniform composite Gauss-Legendre integration rule and employ it to compute the singular integrals appeared in the scheme. Since the approach does not need any background meshes, it can be identified as a meshless method. Error analysis is also given for the method. Illustrative examples are shown clearly the reliability and efficiency of the new scheme and confirm the theoretical error estimates. 相似文献
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In this paper, polynomially-based discrete M-Galerkin and M-collocation methods are proposed to solve nonlinear Fredholm integral equation with a smooth kernel. Using su?ciently accurate numerical quadrature rule, we establish superconvergence results for the approximate and iterated approximate solutions of discrete Legendre M-Galerkin and M-collocation methods in both infinity and L2-norm. Numerical examples are presented to illustrate the theoretical results. 相似文献
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Ali W.K. Sangawi Ali H.M. Murid M.M.S. Nasser 《Applied mathematics and computation》2011,218(5):2055-2068
In this paper we present a boundary integral equation method for the numerical conformal mapping of bounded multiply connected region Ω onto a disk with circular slits. The method is based on some uniquely solvable boundary integral equations with classical adjoint and generalized Neumann kernels. These boundary integral equations are constructed from a boundary relationship satisfied by a function analytic on a multiply connected region. Some numerical examples are presented to illustrate the efficiency of the presented method. 相似文献