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Autor Díaz Díaz, Jesús Ildefonso |
Documentos disponibles escritos por este autor (214)
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Díaz Díaz, Jesús Ildefonso ; Gómez Castro, David ; Shaposhnikova, Tatiana A. ; Zubova, Maria N. | Texas State University | 2019-06-04Our main interest in this article is the study of homogenized limit of a parabolic equation with a nonlinear dynamic boundary condition of the micro-scale model set on a domain with periodically place particles. We focus on the case of particles[...]![]()
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Recent studies on the mechanism governing the Laurentide ice sheet oscillations of the Last Ice Age focus on the most critical effect of the basal hydraulic processes enhanced when the ice is sliding along soft deformable beds. To understand the[...]![]()
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It is well-known that the pressure of a lubricating fluid filling the gap between two solid surfaces satisfies the Reynolds equation involving the distance function, h, between both planes, as a crucial coefficient. Nevertheless, in most of the [...]![]()
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We prove a pointwise gradient estimate for the solution of the Cauchy problem associated to the quasilinear Fisher-KPP type equation with a diffusion coefficient ?(u) satisfying that ?(0) = 0, ?(1) = 1 and a source term ?(u) which is vanishing o[...]![]()
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We study the longtime behavior of the solutions of a second order autonomous differential equation, differing from the one of a harmonic oscillator by a nonlinear friction term being only Hölder continuous. In particular, we show that there are [...]![]()
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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[...]![]()
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We consider the nonlinear Schrodinger equation associated to a singular potential of the form a vertical bar u vertical bar(-(1-m))u + bu, for some In is an element of (0, 1), on a possible unbounded domain. We use some suitable energy methods t[...]![]()
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This paper is a review of recent results (including the author's work) on a two-dimensional free-boundary problem, modeling magnetohydrodynamic equilibrium in a stellarator nuclear fusion device. The main tools used in the paper under review are[...]![]()
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Díaz Díaz, Jesús Ildefonso ; Lerena Guil, María Belen ; Padial Molina, Juan Francisco | Elsevier Science Ltd | 2002An initial-boundary value problem for the nonlinear elliptic–parabolic equation (_(u))t ?_u = G(u)(t, x)+J(u)(t, x) is considered. Here _(s) = min(s, 0) = ?s?, G and J are nonlocal operators. This problem arises in the study of magnetic confinem[...]![]()
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We prove the existence and some qualitative properties of the solution to a two-dimensional free-boundary problem modeling the magnetic confinement of a plasma in a Stellarator configuration. The nonlinear elliptic partial differential equation [...]![]()
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We study the rigidification phenomenon for several thin slender bodies or shells, with a small curvature in the transversal direction to the main length, for which the propagation of singularities through the characteristics is of parabolic type[...]![]()
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Díaz Díaz, Jesús Ildefonso ; Galiano, Gonzalo ; Jungel, Ansgar | Pergamon Elsevier Science Ltd | 1999-06-01The temporal and spatial localization of vacuum sets of the solutions to the drift-diffusion equations for semiconductors is studied in this paper. It is shown that if there are vacuum sets initially then there are vacuum sets for a small time, [...]![]()
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Díaz Díaz, Jesús Ildefonso ; Galiano, Gonzalo ; Jungel, Ansgar | Pergamon Elsevier Science Ltd. | 2001-09This paper is about the drift-diffusion equations for semiconductors. Existence and uniqueness of weak solutions are obtained. The existence is proved by using the regularization technique. The proof of the uniqueness is interesting.![]()
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We study the rigidification phenomenon for several thin slender bodies or shells, with a small curvature in the transversal direction to the main length, for which the propagation of singularities through the characteristics is of parabolic type[...]![]()
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Díaz Díaz, Jesús Ildefonso ; Padial Molina, Juan Francisco ; Rakotoson, Jean Michel Theresien | Cambridge University Press | 2007-09-18We consider some Bernoulli free boundary type problems for a general class of quasilinear elliptic (pseudomonotone) operators involving measures depending on unknown solutions. We treat those problems by applying the Ambrosetti-Rabinowitz minima[...]![]()
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It is known that several features of many react ion-diffusion systems can be studied through an associated Complex Ginzburg-Landau Equation (CGLE). In particular, the study of the catalytic CO oxidation leads to the Krischer-Eiswirth-Ertl model,[...]![]()
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We study the existence and uniqueness of solutions of a nonlinear stochastic pde proposed by R. North and R. F. Cahalan in 1982 for the modeling of non-deterministic variability (as, for instance, the volcano actions) in the framework of energy [...]![]()
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An ambiguity in the mathematical treatment of the study of bound state solutions of the Schrödinger equation for infinite well type potentials (studied for the first time in a pioneering article of 1928 by G. Gamow) is pointed out. An alternativ[...]![]()
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Sire prove the approximate controllability property for some higher order parabolic nonlinear equations of Cahn-Hilliard type when the nonlinearity is of sublinear type at infinity. We also give a counterexample showing that this property may fa[...]![]()
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In this communication we develop and improve some of the results of [4] on the approximate controllability of several semilinear parabolic boundary value problems where the nonlinear term appears either at the second order parabolic equation or [...]![]()
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We consider in this paper distributed systems governed by parabolic evolution equations which can blow up in finite time and which are controlled by initial conditions. We study here the following question : Can one choose the initial condition [...]![]()
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We prove the approximate controllability of several nonlinear parabolic boundary-value problems by means of two different methods: the first one can be called a Cancellation method and the second one uses the Kakutani fixed-point theorem.![]()
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We show how the approximate controllability of nonlinear parabolic problems may fail although it is a well-known property for linear equations. For the case of the obstacle problem the answer depends on the negativeness of the righ hand side ter[...]![]()
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Díaz Díaz, Jesús Ildefonso ; Liñán Martínez, Amable | Real Academia Ciencias Exactas Físicas Y Naturales | 2001We show that there are two curves of initial data (xo, vo) for which the solutions x(t) of the corresponding Cauchy problem associated to the equation xtt + |xí|a_1 xt + x — 0, where a G (0,1), vanish after a finite time. By using asymptotic and[...]![]()
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We prove the existence of a random global attractor for the multivalued random dynamical system associated to a nonlinear multivalued parabolic equation with a stochastic term of amplitude of the order of F. The equation was initially suggested [...]![]()
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The authors consider the Fokker-Planck equation ut=(um)xx+b(u?)x, x> 0, t> 0, with initial and boundary data u(x,0)=u0(x), x> 0, u(0,t)=u1(t), t> 0, u0 having its support in a bounded interval. They concentrate on the case 0![]()
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The Boussinesq system of hydrodynamics equations, arises from a zero order approximation to the coupling between the Navier-Stokes equations and the thermodynamic equation. The presence of density gradients in a fluid means that gravitational p[...]![]()
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We show how to stabilize the uniform oscillations of the complex Ginzburg-Landau equation with periodic boundary conditions by means of some global delayed feedback. The proof is based on an abstract pseudo-linearization principle and a careful [...]![]()
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This paper is devoted to a mathematical analysis of some general models of mass transport and other coupled physical processes developed in simultaneous flows of surface, soil and ground waters. Such models are widely used for forecasting (numer[...]![]()
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We study the differentiability of very weak solutions v is an element of L(1) (Omega) of (v, L* phi)(0) = (f, phi)(0) for all phi is an element of C(2)((Omega) over bar) vanishing at the boundary whenever f is in L(1) (Omega, delta), with delta [...]![]()
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The mathematical analysis of the shape of chemical reactors is studied in this paper through the research of the optimization of its effectiveness g such as introduced by R. Aris around 1960. Although our main motivation is the consideration of [...]![]()
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Díaz Díaz, Jesús Ildefonso ; Hernández, Jesús | Society for Industrial and Applied Mathematics | 1984Let ??R N be a bounded smooth domain, f,g?C 1 (R) , ? 1 ,? 2 ?C 2 (??) , b,c?C 2 (R) nondecreasing, ?,?:R?2 R maximal monotone such that 0??(0)??(0) and consider the weakly coupled elliptic system (?) ?u??(u)f(v) , ??v??(u)g(v) on ? with[...]![]()
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We study a semilinear elliptic equation with a strong absorption term given by a non-Lipschitz function. The motivation is related with study of the linear Schrödinger equation with an infinite well potential. We start by proving a general exist[...]![]()
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Díaz Díaz, Gregorio ; Díaz Díaz, Jesús Ildefonso | American Institute of Mathematical Sciences | 2015-04This paper deals with several qualitative properties of solutions of some stationary equations associated to the Monge-Ampere operator on the set of convex functions which are not necessarily understood in a strict sense. Mainly, we focus our at[...]![]()
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We extend some previous local energy method to the study the free boundary generated by the solutions of quenching type parabolic problems involving a negative power of the unknown in the equation.