Stabilization of the solutions of nonlinear stochastic parabolic equations

Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 41, No. 12, pp.1630–1636, December, 1989.     

Asymptotic behavior of the solutions of certain parabolic equations

Some laws in physics describe the change of a flux and are represented by parabolic equations of the form (*) \documentclass{article}\pagestyle{empty}\begin{document}$$\frac{{\partial u}}{{\partial t}}=\frac{\partial}{{\partial x_j }}(\eta \frac{{\partial u}}{{ax_j}}-vju),$$\end{document} j≤m, where η and v_j are functions of both space and time. We show under quite general assumptions that the solutions of equation (*) with homogeneous Dirichlet boundary conditions and initial condition u(x, 0) = u_o(x) satisfy The decay rate d > 0 only depends on bounds for η, v and G § R^m the spatial domain, while the constant c depends additionally on which norm is considered. For the solutions of equation (*) with homogeneous Neumann boundary conditions and initial condition u₀(x) ≥ 0 we derive bounds d₁u₁ ≤ u(x, t) ≤ d₂u₂, Where d_i, i = 1, 2, depend on bounds for η, v and G, and the u_i are bounds on the initial condition u₀.     

Continuity of weak solutions to certain singular parabolic equations

Sunto Le equazioni paraboliche singolari (1.1)nella introduzione, si presentano come modelli di una classe generale di fenomeni di diffusione con cambio di fase. Le soluzioni deboli sono trovate in senso globale come classi di equivalenza in certi spazi di Sobolev. In questo lavoro si dimostra che le soluzioni deboli ammettono delle rappresentanti continue nell'interno del dominio di definizione. Si danno anche delle condizioni di continuità fino alla frontiera.

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Sponsored by the United States Army under Contract No. DAAG29-80-C-0041. This material is based upon work supported by the National Science Foundation under Grant No. MCS78-09525 A01.     

Stabilization of solutions of initial-boundary problems for quasilinear parabolic equations

Lower bounds are obtained for solutions of the initial-boundary Dirichlet problem for high order equations. Sharp bounds are also obtained for ess sup¦u(x, t)¦ of the Neumann initial-boundary problem for a second- order equation in D=x(t >0), where (Rⁿ, n 2 is a domain with noncompact convex boundary.Translated from Ukrainskii Maternaticheskii Zhurnal, Vol. 44, No. 10, pp. 1441–1450, October, 1992.     

On certain alternating boundary-layer solutions to singularly perturbed parabolic equations

The solution to a special singularly perturbed parabolic problem with a right-hand independent of the spatial variable is studied numerically and analytically.     

Stabilization of solutions to Shilov-type parabolic systems with nonnegative genus

We examine some class of Shilov-type parabolic systems with a nonnegative genus and bounded smooth coefficients depending on time and spatial variables and study the behavior of solutions when t tends to infinity. The initial data at t = 0 belong to a wide class of distributions.     

Classification of certain qualitative properties of solutions for the quasilinear parabolic equations

In this paper, we mainly consider the initial boundary problem for a quasilinear parabolic equation u_t-div(|?u|~(p-2)?u) =-|u|~(β-1) u + α|u|~(q-2 )u,where p 1, β 0, q≥1 and α 0. By using Gagliardo-Nirenberg type inequality, the energy method and comparison principle, the phenomena of blowup and extinction are classified completely in the different ranges of reaction exponents.     

Exact self-similar and two-phase solutions of systems of semilinear parabolic equations

Exact single-wave and two-wave solutions of systems of equations of the Newell—Whitehead type are presented. The Painlevé test and calculations in the spirit of Hirota are used to construct these solutions.Moscow Institute of Electronics and Mathematics. Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 101, No. 2, pp. 189–199, November, 1994.     

Oscillation of solutions for certain impulsive vector parabolic differential equations with delays

In this paper, sufficient conditions are established for H-oscillation of solutions of the following impulsive vector parabolic differential equations with delays

     

Transformation of approximate solutions of linear parabolic equations into asymptotic solutions of quasilinear parabolic equations

Moscow Institute of Electronics and Mathematics. Translated from Matematicheskie Zametki, Vol. 56, No. 6, pp. 122–126, December, 1994.     

A priori estimates for solutions to systems of nonlinear parabolic equations

A class of nondiagonal systems of nonlinear parabolic equations that can be reduced to a scalar parabolic equation in the phase space of a larger dimension is described. In view of such a reduction, it is possible to state the maximum principle for solutions to systems of nonlinear parabolic equations and derive a priori C^2+α-estimates for a solution to the Cauchy problem. Bibliography: 19 titles. Translated fromProblemy Matematicheskogo Analiza, No. 16. 1997, pp. 41–67.     

Stabilization of ill-posed Cauchy problems for parabolic equations

Summary In this paper we study the noncharacteristic Cauchy problem, u_t–(a(x)u_x)_x=0, x(0, l), t.(0, T], u(0, t)=(t), u_x(0,t)=0, 0tT, assuming only L for a. In the case of weak a priori bounds on u, we derive stability estimates on u of Hölder type in the interior and of logarithmic type at the boundary. Also the continuous dependence on a is considered.

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Sunto Nel presente lavoro consideriamo il problema di Cauchy non ben posto u_t= (a(x)u_x)_x, x(0, l), t(0, T), u(0, t)=(t), u_x(0, t)=0, 0tT. Supponiamo che a sia misurabile e limitato inferiormente e superiormente da constanti positive. Introduciamo delle limitazioni a priori su u e dimostriamo la dipendenza continua di u rispetto al dato sia in (0, l)×(0, T) (di tipo hölderiano) sia per x=l (di tipo logaritmico). Consideriamo, inoltre, la dipendenza continua di u da a.