Diffraction of light by ultrasonic waves I. General theory

1953 ◽  
Vol 220 (1142) ◽  
pp. 356-368 ◽  
Keyword(s):  
Integral Equation ◽  
Trial Function ◽  
Plane Waves ◽  
Ultrasonic Waves ◽  
Algebraic Equations ◽  
Approximate Methods ◽  
Trial Solution ◽  
Linear Algebraic Equations ◽  
Special Cases ◽  
Diffraction Of Light

In this paper, following Darwin's (1924) treatment of the reflexion and refraction of light on a transparent homogeneous medium, the problem of the diffraction of light by ultrasonic waves is formulated in terms of the scattering of electromagnetic waves by a periodically perturbed medium. This leads to an integral equation which has been solved for E-polarization with the help of a trial solution for the electric disturbance in the medium in the form of a double infinity of plane waves. The condition that the trial function be a solution of the integral equation leads to ( a ) the frequencies and the directions of the diffracted spectra and ( b ) three infinite sets of linear algebraic equations for the amplitudes N lm and other unknowns occurring in the trial solution. The expressions for the intensities of the diffracted spectra involve the various unknowns of the trial function and can be immediately written down once these unknowns have been determined from the equations. The solution of the equations ( b ) by approximate methods, calculation of intensities for special cases and comparison of various theoretical results with available experimental data are dealt with in part II which follows. A summary of the main results obtained there is given in the Introduction (§1) of the present paper.

On Improved Approximate Solution of the Fredholm Integral Equation

2006 ◽  
Vol 6 (3) ◽  
pp. 264-268
Author(s):  
G. Berikelashvili ◽  
G. Karkarashvili
Keyword(s):  
Integral Equation ◽  
Approximate Solution ◽  
Fredholm Integral Equation ◽  
Algebraic Equations ◽  
Order Convergence ◽  
One Dimensional ◽  
Averaging Operator ◽  
Linear Algebraic Equations ◽  
Convergence Solution

AbstractA method of approximate solution of the linear one-dimensional Fredholm integral equation of the second kind is constructed. With the help of the Steklov averaging operator the integral equation is approximated by a system of linear algebraic equations. On the basis of the approximation used an increased order convergence solution has been obtained.

scholarly journals Exact statistical solution for the hopping transport of trapped charge via finite Markov jump processes

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Andrey A. Pil’nik ◽  
Andrey A. Chernov ◽  
Damir R. Islamov
Keyword(s):  
Charge Transport ◽  
Thin Layers ◽  
Jump Processes ◽  
Dielectric Films ◽  
Algebraic Equations ◽  
Markov Jump ◽  
Statistical Solution ◽  
Linear Algebraic Equations ◽  
Special Cases ◽  
Thin Dielectric Films

AbstractIn this study, we developed a discrete theory of the charge transport in thin dielectric films by trapped electrons or holes, that is applicable both for the case of countable and a large number of traps. It was shown that Shockley–Read–Hall-like transport equations, which describe the 1D transport through dielectric layers, might incorrectly describe the charge flow through ultra-thin layers with a countable number of traps, taking into account the injection from and extraction to electrodes (contacts). A comparison with other theoretical models shows a good agreement. The developed model can be applied to one-, two- and three-dimensional systems. The model, formulated in a system of linear algebraic equations, can be implemented in the computational code using different optimized libraries. We demonstrated that analytical solutions can be found for stationary cases for any trap distribution and for the dynamics of system evolution for special cases. These solutions can be used to test the code and for studying the charge transport properties of thin dielectric films.

On the Interaction at Anti-Flat Deformation of Stress Concentrators of the Type of Cracks and Stringers with Regard to the Layer Manufactured from Miscellaneous Materials

2019 ◽  
Vol 828 ◽  
pp. 81-88
Author(s):  
Nune Grigoryan ◽  
Mher Mkrtchyan
Keyword(s):  
Integral Transform ◽  
Composite Layer ◽  
Singular Integral Equations ◽  
Original System ◽  
Fourier Integral ◽  
Quadrature Formulas ◽  
Algebraic Equations ◽  
Linear Algebraic Equations ◽  
Special Cases ◽  
Tangential Forces

In this paper, we consider the problem of determining the basic characteristics of the stress state of a composite in the form of a piecewise homogeneous elastic layer reinforced along its extreme edges by stringers of finite lengths and containing a collinear system of an arbitrary number of cracks at the junction line of heterogeneous materials. It is assumed that stringers along their longitudinal edges are loaded with tangential forces, and along their vertical edges - with horizontal concentrated forces. In addition, the cracks are laden with distributed tangential forces of different intensities. The case is also considered when the lower edge of the composite layer is free from the stringer and rigidly clamped. It is believed that under the action of these loads, the composite layer in the direction of one of the coordinate axes is in conditions of anti-flat deformation (longitudinal shift). Using the Fourier integral transform, the solution of the problem is reduced to solving a system of singular integral equations (SIE) of three equations. The solution of this system is obtained by a well-known numerical-analytical method for solving the SIE using Gauss quadrature formulas by the use of the Chebyshev nodes. As a result, the solution of the original system of SIE is reduced to the solution of the system of systems of linear algebraic equations (SLAE). Various special cases are considered, when the defining SIE and the SLAE of the task are greatly simplified, which will make it possible to carry out a detailed numerical analysis and identify patterns of change in the characteristics of the tasks.

scholarly journals A convergence theorem for singular integral equations

1981 ◽  
Vol 22 (4) ◽  
pp. 539-552 ◽  
Author(s):  
David Elliott
Keyword(s):  
Integral Equation ◽  
Singular Integral Equation ◽  
Integral Equations ◽  
Singular Integral ◽  
Sufficient Conditions ◽  
Singular Integral Equations ◽  
Convergence Theory ◽  
Cauchy Kernel ◽  
Algebraic Equations ◽  
Linear Algebraic Equations

AbstractThe principal result of this paper states sufficient conditions for the convergence of the solutions of certain linear algebraic equations to the solution of a (linear) singular integral equation with Cauchy kernel. The motivation for this study has been the need to provide a convergence theory for a collocation method applied to the singular integral equation taken over the arc (−1, 1). However, much of the analysis will be applicable both to other approximation methods and to singular integral equations taken over other arcs or contours. An estimate for the rate of convergence is also given.

scholarly journals Numerical solution of a weakly singular integral equation by the method of orthogonal polynomials

2021 ◽  
pp. 98-103
Author(s):  
Sergei M. Sheshko
Keyword(s):  
Integral Equation ◽  
Approximate Solution ◽  
Singular Integral Equation ◽  
Orthogonal Polynomials ◽  
Numerical Solution ◽  
Singular Integral ◽  
Algebraic Equations ◽  
Linear Algebraic Equations ◽  
Expansion Coefficients ◽  
Analytical Expressions

A scheme is constructed for the numerical solution of a singular integral equation with a logarithmic kernel by the method of orthogonal polynomials. The proposed schemes for an approximate solution of the problem are based on the representation of the solution function in the form of a linear combination of the Chebyshev orthogonal polynomials and spectral relations that allows to obtain simple analytical expressions for the singular component of the equation. The expansion coefficients of the solution in terms of the Chebyshev polynomial basis are calculated by solving a system of linear algebraic equations. The results of numerical experiments show that on a grid of 20 –30 points, the error of the approximate solution reaches the minimum limit due to the error in representing real floating-point numbers.

The Problem of an Elastic Stiffener Bonded to a Half Plane

1971 ◽  
Vol 38 (4) ◽  
pp. 937-941 ◽  
Author(s):  
F. Erdogan ◽  
G. D. Gupta
Keyword(s):  
Mechanical Properties ◽  
Integral Equation ◽  
Contact Problem ◽  
Half Plane ◽  
Elastic Constants ◽  
Infinite System ◽  
Stress Singularity ◽  
Algebraic Equations ◽  
Numerical Example ◽  
Linear Algebraic Equations

The contact problem of an elastic stiffener bonded to an elastic half plane with different mechanical properties is considered. The governing integral equation is reduced to an infinite system of linear algebraic equations. It is shown that, depending on the value of a parameter which is a function of the elastic constants and the thickness of the stiffener, the system is either regular or quasi-regular. A complete numerical example is given for which the strength of the stress singularity and the contact stresses are tabulated.

Vibration of a Cracked Cylindrical Shell of Rectangular Planform

1985 ◽  
Vol 52 (4) ◽  
pp. 927-932
Author(s):  
R. Solecki ◽  
F. Forouhar
Keyword(s):  
Cylindrical Shell ◽  
Fourier Transformation ◽  
Circular Cylindrical Shell ◽  
Homogeneous System ◽  
Algebraic Equations ◽  
Discontinuous Functions ◽  
Harmonic Vibrations ◽  
Linear Algebraic Equations ◽  
Special Cases ◽  
Gauss Theorem

Harmonic vibrations of a circular, cylindrical shell of rectangular planform and with an arbitrarily located crack, are investigated. The problem is described by Donnell’s equations and solved using triple finite Fourier transformation of discontinuous functions. The unknowns of the problem are the discontinuities of the slope and of three displacement components across the crack. These last quantities are replaced, using constitutive equations, by curvatures and strain in order to improve convergence and to represent explicitly the singularities at the tips. The formulas for differentiation of discontinuous functions are derived using Green-Gauss theorem. Application of the boundary conditions at the crack leads to a homogeneous system of linear algebraic equations. The frequencies are obtained from the characteristic equation resulting from this system. Numerical results for special cases are provided.

Etude numérique de la fonction de Green scalaire d'une cavité à l'aide d'une nouvelle équation intégrale

1979 ◽  
Vol 57 (2) ◽  
pp. 190-207
Author(s):  
Jacques A. Imbeau ◽  
Byron T. Darling
Keyword(s):  
Integral Equation ◽  
Green’S Function ◽  
Green's Function ◽  
Double Precision ◽  
Integration Formula ◽  
Algebraic Equations ◽  
Equation Intégrale ◽  
Exterior Region ◽  
Von Neumann ◽  
Linear Algebraic Equations

We study numerically, with the aid of an IBM-370 computer, the Green's functions of a cavity afforded by the solutions of a new integral equation (B. T. Darling and J. A. Imbeau. Can. J. Phys. 56, 387 (1978)). A number of prolate spheroidal cavities whose eccentricities cover the complete range zero to one are employed, and the solutions are subject to the Dirichlet and von Neumann conditions at the surface. We use the Gauss–Legendre integration formula to replace the integral equation by a set of linear algebraic equations. The Green's function is evaluated by substituting the solution of this set in the formula of Helmholtz, using the same integration formula. Criteria for the optimization of this procedure also are developed and employed. The Green's function can be determined to high precision except in the immediate vicinity of the surface of the cavity where it suffers a well-known discontinuity. We also explore the use of the Helmholtz formula itself in the exterior region as an integral equation to obtain the Green's function of the cavity. We find that although the precision of the solution is much less than that afforded by the precedingly mentioned integral equation the precision is still within the range of practical application. All calculations used double precision arithmetic (16 significant digits on the IBM-370).

scholarly journals An Efficient Algorithm for Solving Integro-Differential Equation

2019 ◽  
Vol 54 (6) ◽  
Author(s):  
Hassan Hamad AL-Nasrawy ◽  
Abdul Khaleq O. Al-Jubory ◽  
Kasim Abbas Hussaina
Keyword(s):  
Differential Equation ◽  
Approximate Solution ◽  
Difference Equations ◽  
Matrix Equation ◽  
Bernstein Polynomials ◽  
Approximate Solutions ◽  
Algebraic Equations ◽  
Approximate Methods ◽  
Linear Algebraic Equations ◽  
Linear Delay

In this paper, we study and modify an approximate method as well as a new collocation method, which is based on orthonormal Bernstein polynomials to find approximate solutions of mixed linear delay Fredholm integro-differential-difference equations under the mixed conditions. The main purpose of this paper is to study and develop some approximate methods to solve the mixed linear delay Fredholm integro-differential-difference equations. We employ a new algorithm to find approximate solution via perpendicular Bernstein polynomials on the interval [0,1], and we construct a new matrix of derivatives that will be used to find an approximate solution of matrix equation, that will reduce it to the systems of linear algebraic equations. We study the convergence approximate solutions to the exact solutions. Finally, two examples are given and their results are shown in figures to illustrate the efficiency and accuracy of this method. All the computations are implemented using Math14.

scholarly journals The method of secondary sources in electrical engineering science and ill-conditioned matrices.

2020 ◽  
Vol 4 ◽  
pp. 82-94
Author(s):  
V.P. Voloboev ◽  
◽  
V.P. Klymenko ◽  
Keyword(s):  
Integral Equation ◽  
Fredholm Integral Equation ◽  
Discrete Model ◽  
Three Dimensional ◽  
Electric Circuit ◽  
Electrical Circuit ◽  
Algebraic Equations ◽  
New Approach ◽  
Secondary Sources ◽  
Linear Algebraic Equations

A new approach to solving the problem of instability of a system of linear algebraic equations (SLAE) with an ill-conditioned matrix describing a discrete model of the Fredholm integral equation of the sec-ond kind, which reduces the calculation by the method of secondary sources of three-dimensional static and quasi-stationary electromagnetic fields of any geometry in inhomogeneous and nonlinear media, is considered. The essence of the new approach is all about. There is a method for correctly compiling a description of an electrical circuit. In this method, for the first time, when describing an electrical cir-cuit, the parameters of a specific task are taken into account, but they are not taking into account in other methods. As a result, the solution to the problem is stable even in the case of a SLAE with an ill-conditioned matrix. The disadvantage of this method is the description of the electrical circuit in the form of a graph. The description of the discrete model of the integral equation is proposed to be trans-formed to a form of representation that satisfies the method of describing the electric circuit. To achieve this goal, the following tasks have been completed. The requirements of the method of correct compila-tion of the description, which the form of the description of the discrete model of the integral equation must satisfy, are formulated. The analysis of the linear discrete model of the integral equation is carried out, the graph of the discrete model is constructed, and the requirements for the method of transform-ing this graph to the graph that meets the requirements of the method are formulated. A technique for transforming a graph of a discrete model into a graph that meets the requirements of the method has been developed. Final result: a description of a discrete model of the Fredholm integral equation of the second kind, compiled by the method of secondary sources in the form of a graph, satisfying the re-quirements of the method is presented.

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