Geodesic
Elimination of the integral term in the equations of one hereditary system related to the hydromagnetic dynamo
Vestnik KRAUNC. Fiziko-matematičeskie nauki, Tome 42 (2023) no. 1, pp. 180-190 Cet article a éte moissonné depuis la source Math-Net.Ru

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We study a two-dimensional system of integro-differential equations, which is the simplest hereditary model of a two-mode hydromagnetic dynamo. Accounting for the spatial and temporal nonlocality of interactions in dynamo systems is currently being actively studied. In the low-mode approximations of the dynamo equations, one can consider only temporal nonlocality, i.e. heredity (memory). Memory in the system under study is implemented in the form of feedback distributed over all past states of the system. The feedback is represented by a convolution-type integral term of a quadratic combination of phase variables with a fairly general kernel. This term models the quenching of the turbulent field generator ($\alpha$-effect) by a quadratic form in phase variables. In real dynamo systems, such quenchingn is provided by the Lorentz force. The main result of the work is a proof of the possibility of eliminating the integral term for one class of kernels. Such kernels are solutions of a homogeneous linear differential equation with constant coefficients. It is proved that the studed integro-differential system can be replaced by a higher-dimensional differential system with suitable initial conditions for additional phase variables. If the kernel is a solution to an $n$-order equation, then the dimension of the system can reach $3n-2$ and depends on the initial conditions that the kernel satisfies. The work uses classical methods of the theory of differential equations. Examples are given of dynamical systems that arise for some kernels as a result of the elimination of the integral term. The results of the work can be used to verify computational algorithms and program codes developed for solving integro-differential equations.
Keywords: hydromagnetic dynamo, memory, heredity, integro-differential equations. 
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G. M. Vodinchar; E. A. Kazakov. Elimination of the integral term in the equations of one hereditary system related to the hydromagnetic dynamo. Vestnik KRAUNC. Fiziko-matematičeskie nauki, Tome 42 (2023) no. 1, pp. 180-190. http://geodesic.mathdoc.fr/item/VKAM_2023_42_1_a12/

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