Vol 60, No 6 (2024)

In this paper there is investigated the problem of unique solvability of the Caushy problem for the mixed type stochastic differential equation driven by the standard Brownian motion and fractional Brownian motions with Hurst indices

We study the Monge–Amp`ere equation with three independent variables which occurs in electron magnetohydrodynamics. A group analysis of this strongly nonlinear partial derivative equation is carried out. An eleven-parameter transformation preserving the form of the equation is found. A formula is obtained that makes it possible to construct multiparametric families of solutions based on simpler solutions. Two-dimensional reductions leading to simpler partial differential equations with two independent variables. One-dimensional reductions are described, which make it possible to obtain self-similar and other invariant solutions that satisfy ordinary differential equations. Exact solutions with additive, multiplicative and generalized separation of variables are constructed, many of which admit representation in elementary functions. The obtained results and exact solutions can be used to evaluate the accuracy and analyze the adequacy of numerical methods for solving initial boundary value problems described by strongly nonlinear partial differential equations.

This paper considers an optimal control problem in which the controlled process is described by a linear functional equation in a Hilbert space, and the control action is a change of space. Sufficient conditions for the existence of a solution are obtained. The results are generalized to the case when the controlled process is described by a linear variational inequality.

The paper examines the dynamic behavior of elastoviscoplastic media under the action of an external load. For the case of a linear viscosity function and a nonlinear softening function, an explicit-implicit calculation scheme has been constructed that makes it possible to obtain a numerical solution to the original semilinear hyperbolic problem. This approach does not involve the use of the method of splitting into physical processes. Despite this, an explicit computational algorithm was obtained that can be effectively implemented on modern computing systems.

Ниже публикуются краткие аннотации докладов, состоявшихся в весеннем семестре 2024 г. (предыдущее сообщение о работе семинара дано в журнале “Дифференциальные уравнения”. 2023. Т. 59. № 11).