Información del autor
Autor Díaz Díaz, Jesús Ildefonso |
Documentos disponibles escritos por este autor (214)
texto impreso
Díaz Díaz, Jesús Ildefonso ; Tello, Lourdes | Department of Mathematics Texas State University | 2007We study a three dimensional climate model which represents the coupling of the mean surface temperature with the ocean temperature. We prove the existence of a bounded weak solution by a fixed point argument.texto impreso
We start by studying the finite extinction time for solutions of the abstract Cauchy problem u(t) + Au + Bu = 0 where A is a maximal monotone operator and B is a positive operator on a Hilbert space H. We use a suitable spectral energy method to[...]texto impreso
Díaz Díaz, Jesús Ildefonso ; Faghloumi, Ch. | Real Academia Ciencias Exactas Físicas Y Naturales | 2008An application of the results of this paper proves that there is not always an economic benefit when destroying the environment for planting an alternative industrial project. Our criterion, to act, to delay or to deny the industrial investment [...]texto impreso
texto impreso
Díaz Díaz, Jesús Ildefonso ; Bejenaru, Ioan ; Vrabie, Ioan I. | Texas State University, Department of Mathematics | 2001The authors obtain an approximate controllability result for the nonlinear equation $y'+Ay+F(t,y)y=h(t)$ with the initial condition where $x$ is the control and $A$ generates a $C_0$-semigroup in a Hilbert space. The Schauder fixed poi[...]texto impreso
The purpose of this paper is to study the problem (P) ??u+u??=f in ?, u=0 on ??, u???L1(?), u> 0 in ?, where ? is a bounded smooth open set of RN, f?0, f?L1(?) and 0texto impreso
Díaz Díaz, Jesús Ildefonso ; Lerena Guil, María Belen ; Padial Molina, Juan Francisco ; Rakotoson, Jean Michel Theresien | Elsevier | 2004-04-10We prove the existence and the regularity of weak solutions of a nonlocal elliptic–parabolic free-boundary problem involving the notions of relative rearrangement and monotone rearrangement. The problem arises in the study of the dynamics of a m[...]texto impreso
Díaz Díaz, Jesús Ildefonso ; Hetzer, G. ; Tello del Castillo, Lourdes | Pergamon-Elsevier Science | 2006-05-01Energy balance climate models of Budyko type lead to reaction-diffusion equations with slow diffusion and memory on the 2-sphere. The reaction part exhibits a jump discontinuity (at the snow line). Here we introduce a Babuska-Duhem hysteresis in[...]texto impreso
We give a simple mathematical proof of the popular strategy "donít put o§ for tomorrow what you can do today" by using the HUM method due to Jacques-Louis Lions for the controllability of linear systems.texto impreso
We study a class of optimization dynamics problems related to investment under uncertainty. The general model problem is reformulated in terms of an obstacle problem associated to a second-order elliptic operator which is not in divergence form.[...]texto impreso
texto impreso
texto impreso
Wt,give some negative and positive results on the approximate controllability of the Stokes system formulated on a cylinder Omega = G x R of R-3 when the control is a density of external unidirectional forces. We distinguish the case where the d[...]texto impreso
This paper concerns the blow-up behavior of large radial solutions of polyharmonic equations with power nonlinearities and positive radial weights. Specifically, we consider radially symmetric solutions of mu = c(|x|)|u| p on an annulus {x ? Rn [...]texto impreso
Díaz Díaz, Jesús Ildefonso ; Hetzer, Georg | Department of Mathematics Texas State University | 2007This note is devoted to stick-slip aspects of the motion of a dry friction damped oscillator under weak irregular forcing. Our main result complements[10, Theorem 3.(a)] and is also related to [1], where a non-Lipschitz model for Coulomb frictio[...]texto impreso
Given a bounded open set Omega subset of R-n and a continuous convex function Phi: L-2(Omega) -> R, let us consider the following damped wave equation u(tt) - Delta u + partial derivative Phi(u(t)) 0, (t, x) is an element of (0, +infinity) x Om[...]texto impreso
Díaz Díaz, Jesús Ildefonso ; Casal, Alfonso C. ; Vegas Montaner, José Manuel | Dynamic Publishers, Inc. | 2009Blow-up phenomena are analyzed for both the delay-differential equation (DDE) u'(t) = B'(t)u(t - tau), and the associated parabolic PDE (PDDE) partial derivative(t)u=Delta u+B'(t)u(t-tau,x), where B : [0, tau] -> R is a positive L(1) function w[...]texto impreso
The authors study the behaviour of the solution of the Signorini problem at the boundary. In particular a necessary and quasi-sufficient condition for the existence of a nonempty coincidence set and some estimates on the location of the coincide[...]texto impreso
We study the existence and multiplicity of solutions, strictly positive or nonnegative having a free boundary (the boundary of the set where the solution vanishes) of some one-dimensional quasilinear problems of eigenvalue type with possibly sin[...]texto impreso
texto impreso
texto impreso
The author studies by the local energy method the compactness of the support of the solutions to nonlinear elliptic or parabolic equations (in this last case also the Stefan-like case is considered).texto impreso
We show some compactness properties of the operator f--u, where u is the solution of the nonlinear diffusion equation ut???(u)=f on (0,T)×? associated with the parabolic boundary conditions ?(u)=0 on (0,T)×?? and u(0,?)=u0(?) on ?, u0 a given fu[...]texto impreso
The authors study the nonlinear porous media type equation ut(t,x)???(u(t,x))=0 for (t,x)?(0,?)×?, ?(u(t,x))=0 for (t,x)?(0,?)×??, u(0,x)=u0(x) for x??, with ? an open set in Rn, and ? a regular, real, continuous, nondecreasing function. In the [...]texto impreso
The (simplified) Backus' Problem (BP) consists in finding a harmonic function u on the domain exterior to the three dimensional unit sphere S, such that u tends to zero at infinity and the norm of the gradient of u takes prescribed values g on S[...]texto impreso
Global time-delay autosynchronization is known to control spatiotemporal turbulence in oscillatory reactiondiffusion systems. Here, we investigate the complex Ginzburg-Landau equation in the regime of spatiotemporal turbulence and study numerica[...]texto impreso
We consider the Cauchy problem ut = ?(u)xx + ?(u), (t, x) ? R+ × R, u(0, x) = u0(x), x ? R, when the increasing function ? satisfies that ?(0) = 0 and the equation may degenerate at u = 0 (in the case of ?? (0) = 0). We consider the case of u0 ?[...]texto impreso
Bui, L.T.T. ; Dao, A. N ; Díaz Díaz, Jesús Ildefonso | Texas State University, Department of Mathematics | 2017We prove the existence of solutions of the viscous Cahn-Hilliard equation in whole domain when the nonlinear term in the second order diffusion grows as uq for the critical case when N > = 3. Our results improve the ones in [9, 12].texto impreso
In the book by U. Hornung, Chapter 6, the author proposes an homogenization strategy for the effective behavior of some chemical processes involving adsorption and reactions arising in porous media. Rigorous proofs of the convergence results are[...]texto impreso
This paper gives a very brief review of some properties of solutions of quasilinear scalar elliptic and parabolic partial differential equations in a spatial domain ?. Emphasis is laid on nonlinearities which allow the support of the solutions t[...]texto impreso
We present a new proof of comparison results via Steiner symmetrization for solutions of elliptic equations. This proof relies upon a "level sets" argument.texto impreso
Díaz Díaz, Jesús Ildefonso ; Alvino, A. ; Trombetti, G. ; Lions, P.L. | John Wiley & SONS INC | 1996-03We give some comparison results for elliptic equations by using Steiner symmetrization.texto impreso
Díaz Díaz, Jesús Ildefonso ; Rakotoson, Jean-Michel | Department of Mathematics Texas State University | 2014We revisit the regularity of very weak solution to second-order elliptic equations Lu = f in ? with u = 0 on ?? for f ? L1 (?, ?), ?(x) the distance to the boundary ??. While doing this, we extend our previous results(and many others in the lite[...]texto impreso
texto impreso
In this paper we use some energy methods to study the location (and formation) of a free boundary arising in some unilateral problems, for instance, in the obstacle problem and the Stefan problem.texto impreso
We obtain existence and uniqueness of solutions with compact support for some nonlinear elliptic and parabolic problems including the equations of one-dimensional motion of a non-newtonian fluid. Precise estimates for the support of these soluti[...]texto impreso
Obtains existence and uniqueness of solutions with compact support for some nonlinear elliptic and parabolic problems including the equations of one-dimensional motion of a non-newtonian fluid. Precise estimates for the support of these solution[...]texto impreso
In 1757, Leonhard Euler started the study of the tallest column, i.e. the shape of a stable column with the symmetry of revolution, such that it attains the maximum height once the total mass is prescribed, buckling due to the effect of a load s[...]texto impreso
The authors study the nonlinear elliptic equation (*) ?div(a(x,u,Du))?div(?(u))+g(x,u)=f(x)in ? with the boundary condition (??) u=0 on ??, where ? is a bounded open subset of RN, A(u)=?div(a(x,u,Du)) is a nonlinear operator of Leray-Lions type[...]texto impreso
The authors show the uniqueness and give some necessary and sufficient conditions for the existence of positive solutions of the equation ??pu=f(x,u), where ?p denotes the p-Laplacian and f(x,r)/rp?1 is assumed to be decreasingtexto impreso
The authors study the existence of weak solutions for the following system: ut???(u)?F(u,v), vt???(v)?G(u,v) in (0,T)×?, ?(u)=?(v)=0 on (0,T)×??, u(0,x)=u0(x), v(0,x)=v0(x) in the region ???Rn with smooth boundary ??. The functions ?,?:R?R are a[...]texto impreso
We prove some existence (and sometimes also uniqueness) of weak solutions to some stationary equations associated to the complex Schrödinger operator under the presence of a singular nonlinear term. Among other new facts, with respect some previ[...]texto impreso
Díaz Díaz, Jesús Ildefonso ; Muñoz Montalvo, Ana Isabel ; Schiavi, Emanuele | Pergamon-Elsevier Science Ltd. | 2007-02This paper deals with the mathematical analysis of a nonlinear system of three differential equations of mixed type. It describes the generation of fast ice streams in ice sheets flowing along soft and deformable beds. The system involves a nonl[...]texto impreso
The authors consider first-order equations in "conservation laws'' form perturbed by a semilinear nonlinearity of monotone type. The known existence and uniqueness results for conservation laws—results due to Kruzhkov—are easily adapted to this [...]texto impreso
Díaz Díaz, Jesús Ildefonso ; Bermejo, R. ; Carpio, Jaime ; Galán del Sastre, Pedro | Birkhäuser | 2008-07-11We present a finite element algorithm of a climate diagnostic model that takes as a climate indicator the atmospheric sea-level temperature. This model belongs to the category of energy balance models introduced independently by the climatologis[...]texto impreso
Díaz Díaz, Jesús Ildefonso ; Casal, A.C. ; Vegas Montaner, José Manuel | Pergamon-Elsevier Science | 2009-12-15We give sufficient conditions to have the finite extinction for all solutions of linear parabolic reaction-diffusion equations of the type partial derivative u/partial derivative t - Lambda u = -M(t)u(t - tau, x) (1) with a delay term tau > 0, [...]texto impreso
Casal, Alfonso C. ; Díaz Díaz, Jesús Ildefonso ; Vegas Montaner, José María | American Institute of Mathematical Sciences | 2011We prove that the mere presence of a delayed term is able to connect the initial state u0 on a manifold without boundary (here assumed given as the set ?? where ? is an open bounded set in RN ) with the zero state on it and in a finite time even[...]texto impreso
The finite time extinction phenomenon (the solution reaches an equilibrium after a finite time) is peculiar to certain nonlinear problems whose solutions exhibit an asymptotic behavior entirely different from the typical behavior of solutions as[...]texto impreso
The finite time extinction phenomenon (the solution reaches an equilibrium after a finite time) is peculiar to certain nonlinear problems whose solutions exhibit an asymptotic behavior entirely different from the typical behavior of solutions as[...]