The inverse problem for an equation of mixed parabolic-hyperbolic type

We study the inverse problem related to finding the unknown right-hand side of the equation of mixed parabolic-hyperbolic type in a rectangular domain. A uniqueness criterion for the solution is established. The solution is constructed as the sum of the series in eigenfunctions of the corresponding one-dimensional spectral problem.     

Sign-definiteness of solution to inhomogeneous higher-order equation of mixed parabolic-hyperbolic type

We study solutions of a polycaloric equation and an equation of mixed parabolichyperbolic type of the second order. We prove the sign-definiteness of the solution in dependence of the right-hand side of the equation. Based on these results we study the sign-definiteness of a solution to a higher-order inhomogeneous equation of mixed parabolic-hyperbolic type in dependence on the right-hand side of the equation.     

On an inhomogeneous Tricomi problem for a parabolic-hyperbolic equation

We consider an inhomogeneous Tricomi problem for a parabolic-hyperbolic equation with noncharacteristic type change line and with Frankl type matching condition for the normal derivatives on the type change line. The auxiliary function method is used to establish an a priori estimate of the solution. The existence of the solution is proved by the spectral method.     

On an inhomogeneous problem for parabolic-hyperbolic equation

We study a boundary value problem for an inhomogeneous parabolic-hyperbolic equation with a noncharacteristic type change line. Boundary conditions of the first kind are posed on characteristics in the parabolic and hyperbolic parts of the domain where the equation is given, and a condition of the third kind is posed on the noncharacteristic part of the boundary in the parabolic part. First, we study the solvability of an inhomogeneous initial–boundary value problem for a parabolic equation.     

On a Frankl-type problem for a mixed parabolic-hyperbolic equation

We state a new nonlocal boundary value problem for a mixed parabolic-hyperbolic equation. The equation is of the first kind, i.e., the curve on which the equation changes type is not a characteristic. The nonlocal condition involves points in hyperbolic and parabolic parts of the domain. This problem is a generalization of the well-known Frankl-type problems. Unlike other close publications, the hyperbolic part of the domain agrees with a characteristic triangle. We prove unique solvability of this problem in the sense of classical and strong solutions.     

Boundary-value problem for a mixed parabolic-hyperbolic equation of the third order

The unique solvability of a certain boundary-value problem is proved for a mixed parabolic-hyperbolic type equation of the third order.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 47, No. 1, pp. 20–29, January, 1995.     

The inverse problem for a mixed-type parabolic-hyperbolic equation in a rectangular domain

In this paper with the help of the spectral method we obtain a criterion for the unique solvability of the inverse problem for a mixed-type parabolic-hyperbolic equation in a rectangular domain. This problem implies the search of the unknown right-hand side.     

Tricomi problem for a mixed parabolic-hyperbolic equation in a rectangular domain

Mathematical Notes - For a class of equations of mixed type, we study an analog of the Dirichlet problem satisfying the conjugation conditions on the line of change of the type. We establish a...     

Inverse problem for an equation of parabolic-hyperbolic type with a nonlocal boundary condition

For an equation of the parabolic-hyperbolic type, we consider an inverse problem with a nonlocal condition relating solution derivatives that belong to different types of the equation in question. We justify a uniqueness criterion and prove the existence of a solution of the problem by the spectral analysis method. We prove the stability of the solution with respect to the nonlocal boundary condition.     

Initial-boundary value problem for an equation of mixed parabolic-hyperbolic type in a rectangular domain

The spectral analysis method is used to establish a uniqueness criterion and prove the existence of a solution of the first initial-boundary value problem for a special equation of mixed type.     

On a non-local boundary problem for a parabolic-hyperbolic equation involving a Riemann-Liouville fractional differential operator

In the present work, a non-local boundary value problem with special gluing conditions for a mixed parabolic-hyperbolic equation with parameter is considered. The parabolic part of this equation is a fractional analogue of heat equation and the hyperbolic part is the telegraph equation. The considered problem is reduced, for positive values of the parameter, to an equivalent system of the second kind Volterra integral equations. Due to the influence of the fractional diffusion equation, the looked for solution belongs to a specific class of functions. The method of the Green functions and the properties of integro-differential operators are on the basis of the investigation.     

Solution of mixed problems with boundary elastic-force control for the telegraph equation

In terms of a finite-energy generalized solution of the telegraph equation, for any time interval T, we consider the problem on the boundary elastic-force control u _x (0, t) = μ(t) at the endpoint x = 0 for the process described by the Klein-Gordon-Fock equation under the condition that the other endpoint x = l is either fixed, or free, or is controlled by an elastic force. For any time interval T, we obtain the solution u(x, t) in closed form.     

Mixed problems for the string vibration equation with homogeneous boundary conditions and inhomogeneous nonlocal conditions

We consider four mixed problems for the string vibration equation with homogeneous boundary and inhomogeneous nonlocal conditions of the first or second kind and with zero initial conditions. By using recursion relations, we find generalized solutions of the abovementioned problems.     

Initial value/boundary value problems for fractional diffusion-wave equations and applications to some inverse problems

We consider initial value/boundary value problems for fractional diffusion-wave equation: , where 0<α?2, where L is a symmetric uniformly elliptic operator with t-independent smooth coefficients. First we establish the unique existence of the weak solution and the asymptotic behavior as the time t goes to ∞ and the proofs are based on the eigenfunction expansions. Second for α∈(0,1), we apply the eigenfunction expansions and prove (i) stability in the backward problem in time, (ii) the uniqueness in determining an initial value and (iii) the uniqueness of solution by the decay rate as t→∞, (iv) stability in an inverse source problem of determining t-dependent factor in the source by observation at one point over (0,T).     

An integral equation technique for scattering problems with mixed boundary conditions

This paper presents an integral formulation for Helmholtz problems with mixed boundary conditions. Unlike most integral equation techniques for mixed boundary value problems, the proposed method uses a global boundary charge density. As a result, Calderón identities can be utilized to avoid the use of hypersingular integral operators. Numerical results illustrate the performance of the proposed solution technique.     

On the solvability of some boundary value problems for the inhomogeneous polyharmonic equation with boundary operators of the Hadamard type

We study the properties of fractional integro-differential operators. As an application, we analyze the solvability of some boundary value problems for the inhomogeneous polyharmonic equation in the unit ball. These problems generalize the Dirichlet and Neumann problems to the case of fractional boundary operators.     

On a nonlocal problem for a degenerating parabolic-hyperbolic equation

For an equation of mixed type in a rectangular domain, we use spectral analysis to establish a uniqueness criterion for the solution of a problem with a nonlocal condition relating the values of the unknown solution that belong to different types of the considered equation. We prove the stability of the solution with respect to the nonlocal condition.