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1

Solving linear Fredholm integro-differential equation by Nyström method

Tair Boutheina, Guebbai Hamza, Segni Sami, Ghiat Mourad

Journal of Applied Mathematics and Computational Mechanics

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2021

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Vol. 20, nr 3

53--64

EN

The study of the solution’s existence and uniqueness for the linear integro-differential Fredholm equation and the application of the Nyström method to approximate the solution is what we will present in this paper. We use the Neumann theorem to construct a sufficient condition that ensures the solution’s existence and uniqueness of our problem in the Banach space C1 [a,b]. We have applied the Nyström method based on the trapezoidal rule to avoid adding other conditions in order to the approximation method’s convergence. The Nyström method discretizes the integro-differential equation into solving a linear system. Only with the existence and uniqueness condition, we show the solution’s existence and uniqueness of the linear system and the convergence of the numerical solution to the exact solution in infinite norm sense. We present two theorems to give a good estimate of the error. Also, to show the efficiency and accuracy of the Nyström method, some numerical examples will be provided at the end of this work.

2

The implicit numerical method for the one-dimensional anomalous subdiffusion equation with a nonlinear source term

Błasik Marek

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2021

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Vol. 69, nr 6

art. no. e138240

EN

In the paper, the numerical method of solving the one-dimensional subdiffusion equation with the source term is presented. In the approach used, the key role is played by transforming of the partial differential equation into an equivalent integro-differential equation. As a result of the discretization of the integro-differential equation obtained an implicit numerical scheme which is the generalized Crank-Nicolson method. The implicit numerical schemes based on the finite difference method, such as the Carnk-Nicolson method or the Laasonen method, as a rule are unconditionally stable, which is their undoubted advantage. The discretization of the integro-differential equation is performed in two stages. First, the left-sided Riemann-Liouville integrals are approximated in such a way that the integrands are linear functions between successive grid nodes with respect to the time variable. This allows us to find the discrete values of the integral kernel of the left-sided Riemann-Liouville integral and assign them to the appropriate nodes. In the second step, second order derivative with respect to the spatial variable is approximated by the difference quotient. The obtained numerical scheme is verified on three examples for which closed analytical solutions are known.

3

Application of the Taylor differential transformation for solving the integro-differential equations

Grzymkowski R., Pleszczyński M.

Silesian Journal of Pure and Applied Mathematics

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2018

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Vol. 8, iss. 1

33--48

EN

A method of solving the integro-differential equations is presented. The discussed equations will be solved by the Taylor differential transformation. By using appropriate properties of this transformation the integro-differential equation will be transformed to a respective recurrence equation. Unfortunately, the high degree of generality and complexity of such defined problem does not allow to obtain the solution in general form. Each equation requires a special method of solution.

4

Transients in Transformers with Non-Uniform Inductance and Capacitance Distributions

Saied M. M.

Electrical Power Quality and Utilisation. Journal

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2017

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Vol. 20, no. 1

7--14

EN

The electromagnetic transients in transformer windings exhibiting location–dependent inductances and capacitances are investigated in the time domain. Analytical functions describing this dependence are assumed and incorporated in the two integro–differential equations governing the transient voltage and current distributions. The boundary conditions are available from the source initiating the transients and the winding’s end termination. A numerical procedure is applied in order to get frequency domain solutions for the voltage and current in the form of Interpolating and Parametric Functions. The numerical Laplace inversion is then applied to these s–domain expressions. Results pertinent to transients initiated by step- and double-exponential impulse sources are presented and discussed. All possible transformers’ neutral connections are considered. The possible error introduced by neglecting either or both of the inductance and capacitance non-uniformities is addressed. Results indicate that the main error is attributed to neglecting the inductance non-uniformity, whereas the impact of the capacitance non-uniformity is relatively small. In most cases, the winding’s copper and insulation losses have a small effect on the transient response.

5

Invariance of integro-differential equations with moving region of integration

Zawistowski Z. J.

Journal of Technical Physics

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2006

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Vol. 47, no 2

103-112

EN

General criterion of invariance of integro-differential equations under the Lie symmetry group of point transformations is derived. It is a generalization of the previous form of the criterion to the case of a moving range of integration. This is the situation when a region of integration depends on external, with respect to integration, variables what leads to its explicit dependence on a group parameter, so the region of integration moves under symmetry transformations. General case of dependence on independent and dependent variables and their derivatives is considered.

6

Electron plasma upper hybrid kinetic symmetries

Taranov V. B., Zawistowski Z. J.

Journal of Technical Physics

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2003

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Vol. 44, no 3

303-309

EN

Symmetry group of integro-difFerential equations describing nonlinear upper hybrid waves in magnetized electron plasma is found. It is shown that the extension of the symmetry in the cold plasma limit allows us to build the general solution in this case.

7

Mathematical Modeling of the Competition Between Acquired Immunity and Cancer

Kolev M.

International Journal of Applied Mathematics and Computer Science

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2003

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Vol. 13, no 3

289-296

EN

In this paper we propose and analyse a model of the competition between cancer and the acquired immune system. The model is a system of integro-differential bilinear equations. The role of the humoral response is analyzed. The simulations are related to the immunotherapy of tumors with antibodies.

8

On symmetries of integro-differential equations

Zawistowski Z.J.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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1998

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Vol. 46, nr 2

187-197

EN

A new, general method is presented for the determination of Lie symmetry groups of integro-differential equations. The exhibited method is a natural extension of the famous Ovsiannikov method developed for differential equations. The method leads to significant applications for instance to the Vlasov-Maxwell equations, which are integro-differential type irreducible to differential equations.