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Autor Díaz Díaz, Jesús Ildefonso |
Documentos disponibles escritos por este autor (214)
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This work deals with some numerical experiments regarding the distributed control of semilinear parabolic equations of the type y(t) - y(xx) + f (y) = u(Xw), in (0, 1) x (0, T), with Neumann and initial auxiliary conditions, where w is an open s[...]![]()
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The paper studies the approximate controllability for the Burgers equation. Due to the presence of a superlinear term, an obstruction phenomenon arises which implies a lack of approximate controllability in spaces of type L^p or $C$. However, th[...]![]()
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We obtain the existence of solutions of a two-dimensional free boundary problem modelling the magnetic confinement of a plasma in a Stellarator configuration. The nonlinear elliptic equation was obtained from the 3-D MHD system by Hender and Car[...]![]()
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In this communication, we consider the stationary problem of a non-linear parabolic system which arises in the context of dry-land vegetation. In the first part, we examine the existence and multiplicity of biomass stationary solutions, in terms[...]![]()
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We consider a mathematical model, posed by J.E. Scheinkman, simulating that an industrial project takes place into the environment without destroying it. We introduce a change of variable leading the formulation to a nonlinear evolution problem [...]![]()
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Díaz Díaz, Jesús Ildefonso ; Díaz Díaz, Gregorio ; Otero Juez, Jesús | Amsterdam Elsevier Science 2000 | 2006-04We show the existence and uniqueness of a viscosity solution for an oblique nonlinear problem suggested by the study of the Backus problem on the determination of the external gravitational potential of the Earth from surface measurements of the[...]![]()
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"We consider some degenerate parabolic problems on a convex (or starshaped) ring. We prove that if the initial data have convex (or starshaped) level sets, then the solution u(t,?) has the same property for any positive t. Similar results are sh[...]![]()
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The authors present and study a problem which models the evolution of the ice sheet in the Laurentide. They consider a one-dimensional problem in (3-dimensional) space which involves three parameters: the ice thickness h , the amount of water fl[...]![]()
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Díaz Díaz, Jesús Ildefonso ; Calvo, N. ; Durany, J. ; Schiavi, E. ; Vázquez, C. | Society for Industrial and Applied Mathematics | 2002This paper deals with the weak formulation of a free (moving) boundary problem arising in theoretical glaciology. Considering shallow ice sheet flow, we present the mathematical analysis and the numerical solution of the second order nonlinear d[...]![]()
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The fully nonlinear parabolic problem (P_{\text{}) u t =min{?,?u} for ?×R + , u=0 for ??×R + , u(x,0)=u 0 (x) for ? , occurs in some cases of Bellman's equation of dynamic programming. The author studies questions of asymptotic behavior[...]![]()
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Díaz Díaz, Jesús Ildefonso ; Antontsev, S.N. | Real Academia Ciencias Exactas Físicas Y Naturales | 2009We prove several uniform L(1)-estimates on solutions of a general class of one-dimensional parabolic systems, mainly coupled in the diffusion term, which, in fact, can be of degenerate type. They are uniform in the sense that they don't depend o[...]![]()
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We consider a mathematical model related to the stationary regime of a plasma of fusion nuclear, magnetically confined in a Stellarator device. Using the geometric properties of the fusion device, a suitable system of coordinates and averaging m[...]![]()
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The main result of the paper is the uniqueness of nonnegative solutions of the Cauchy problem and of the first and mixed boundary value problems for a class of degenerate parabolic equations which includes the model equation ut=(um)xx+(un)x, whe[...]![]()
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Díaz Díaz, Jesús Ildefonso ; De Thelin, Francois | Society for Industrial and Applied Mathematics | 1994This paper studies the Cauchy-Dirichlet problem associated with the equation b(u)t - div (\del u - K (b(u)) e\p-2 (del u - K (b(u))e)) + g (x, u) = f (t, x). This problem arises in the study of some turbulent regimes: flows of incompressible tur[...]