A pseudospectral method for nonlinear Duffing equation involving both integral and non‐integral forcing terms

The Legendre pseudospectral method is developed for the numerical solution of nonlinear Duffing equation involving both integral and non‐integral forcing terms. By using differentiation matrix, the problem is reduced to the solution of a system of algebraic equations. The method is general, easy to implement, and yields very accurate results. Numerical experiments are presented to demonstrate the accuracy and the efficiency of the proposed computational procedure. Copyright © 2014 John Wiley & Sons, Ltd.     

Characterization of balls by Riesz-potentials

For a bounded convex domain and consider the unit- density Riesz-potential . We show in this paper that u  =  const. on ∂G if and only if G is a ball. This result corresponds to a theorem of L.E. Fraenkel, where the ball is characterized by the Newtonian-potential (α = 2) of unit density being constant on ∂G. In the case α = N the kernel |x − y| ^α-N is replaced by  − log|x − y| and a similar characterization of balls is given. The proof relies on a recent variant of the moving plane method which is suitable for Green-function representations of solutions of (pseudo-)differential equations of higher-order.      

Characterization of balls by generalized Riesz energy

We show that balls, circles and 2‐spheres can be identified by generalized Riesz energy among compact submanifolds of the Euclidean space that are either closed or with codimension 0, where the Riesz energy is defined as the double integral of some power of the distance between pairs of points. As a consequence, we obtain the identification by the interpoint distance distribution.     

Two-dimensional transport equation as Fredholm integral equation

The transport equation has many applications in various fields of science and engineering. In this paper we shown that we can transform a transport equation in two-dimensional case into a Fredholm integral equation of the second kind with a compact integral operator for the angular flux by using the Sumudu transform.     

An integral equation of elasticity

In this work a certain mixed problem in R for the Lamé equations in the theory of elasticity is reduced to the integral equation An explicit formula for the solutions is given for either Ω = {x:x₂ > 0} or Ω = {x:∥x∥<r}. The question of smoothness of the solutions is also discused. Another formulae on Ω = {x:∥x∥<r} are found in [5], [4]. It seems that the techniques used below allows a deeper investigation of properties of the solutions to problem (*).     

An integral equation in conformal geometry

Motivated by Carleman's proof of the isoperimetric inequality in the plane, we study the problem of finding a metric with zero scalar curvature maximizing the isoperimetric ratio among all zero scalar curvature metrics in a fixed conformal class on a compact manifold with boundary. We derive a criterion for the existence and make a related conjecture.     

On first-order quasi-variational inequalities with integral terms

This paper deals with first-order quasi-variational inequalities with integral terms associated with impulsive and switching control of piecewise-deterministic processes. Two formulations of quasi-variational inequalities are studied, characteristic and viscosity, and the relations between them are discussed. As a tool we apply convex analysis methods.     

Approximating the Riemann-Stieltjes integral in terms of generalised trapezoidal rules

Error bounds in approximating the Riemann-Stieltjes integral in terms of some new generalised trapezoidal rules are given. Applications for approximating the Riemann integral of a two-function product are provided as well.     

A solution of an integral equation

In this paper an integral equation $$\int\limits_0^\infty {f(u)f\left( {\tfrac{x}{u}} \right)\tfrac{{du}}{u} = g(x)} $$ is studied.     

Numerical solution of Volterra integral equation

Summary This paper discusses the use of Gregory's formula for numerical integration of Volterra linear integral equations of the second type. The order of magnitude of the truncation error and the asymptotic behavior of this error are obtained by means of recursive inequalities.     

非线性Volterra-Stieltjes积分方程的解

利用Schauder不动点定理和饱和解的理论,研究下列非线性Volterrastieltjes积分方程x(t)=h(t) ∫t0u(t,s,x(s))dsg(t,s).在适当的条件下,证明了上述方程在[0, ∞)上有连续解.     

Solutions of some singular integral equation

A singular integral equation with a Holderian second member function on [a,b] is considered and solved for four different type of kernels in the class of functions that are unbounded at the end points of the interval.     

An integral equation method in conformal mapping

This paper describes an integral equation method for computing the conformal mapping of a given simply-connected domain onto the interior of the unit circle. Simple error estimates are available when the given domain possesses symmetry, and results are presented for a number of trial problems of this form.This work was supported by the National Science Foundation, under grant GP. 4213.On leave from Mathematics Division, National Physical Laboratory, Teddington, Middlesex, England.     

Boundary integral equation method in micropolar elasticity

This paper presents the integral representations of the displacement and rotation fields of the micropolar continuum, and the regularized integral representations of the traction and couple vector. Thus the boundary integral equations and the boundary integro-differential equations are derived. In addition, the formulation for crack problems is given by both the boundary integral equations and the boundary integro-differential equations.