Displaying similar documents to “Domain decomposition methods coupled with parareal for the transient heat equation in 1 and 2 spatial dimensions”

Inequalities involving heat potentials and Green functions

Neil A. Watson (2015)

Mathematica Bohemica

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We take some well-known inequalities for Green functions relative to Laplace’s equation, and prove not only analogues of them relative to the heat equation, but generalizations of those analogues to the heat potentials of nonnegative measures on an arbitrary open set E whose supports are compact polar subsets of E . We then use the special case where the measure associated to the potential has point support, in the following situation. Given a nonnegative supertemperature on an open set...

Uniform analytic-Gevrey regularity of solutions to a semilinear heat equation

Todor Gramchev, Grzegorz Łysik (2008)

Banach Center Publications

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We study the Gevrey regularity down to t = 0 of solutions to the initial value problem for a semilinear heat equation t u - Δ u = u M . The approach is based on suitable iterative fixed point methods in L p based Banach spaces with anisotropic Gevrey norms with respect to the time and the space variables. We also construct explicit solutions uniformly analytic in t ≥ 0 and x ∈ ℝⁿ for some conservative nonlinear terms with symmetries.

Explicit solutions for a one-phase Stefan problem with temperature-dependent thermal conductivity

María F. Natale, Domingo A. Tarzia (2006)

Bollettino dell'Unione Matematica Italiana

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We study a one-phase Stefan problem for a semi-infinite material with temperature-dependent thermal conductivity with a constant temperature or a heat flux condition of the type - q 0 / t ( q 0 > 0 ) at the fixed face x = 0 . We obtain in both cases sufficient conditions for data in order to have a parametric representation of the solution of the similarity type for t t 0 > 0 with t 0 an arbitrary positive time. These explicit solutions are obtained through the unique solution of an integral equation with the time...

Tykhonov well-posedness of a heat transfer problem with unilateral constraints

Mircea Sofonea, Domingo A. Tarzia (2022)

Applications of Mathematics

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We consider an elliptic boundary value problem with unilateral constraints and subdifferential boundary conditions. The problem describes the heat transfer in a domain D d and its weak formulation is in the form of a hemivariational inequality for the temperature field, denoted by 𝒫 . We associate to Problem 𝒫 an optimal control problem, denoted by 𝒬 . Then, using appropriate Tykhonov triples, governed by a nonlinear operator G and a convex K ˜ , we provide results concerning the well-posedness...

Gradient estimates of Li Yau type for a general heat equation on Riemannian manifolds

Nguyen Ngoc Khanh (2016)

Archivum Mathematicum

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In this paper, we consider gradient estimates on complete noncompact Riemannian manifolds ( M , g ) for the following general heat equation u t = Δ V u + a u log u + b u where a is a constant and b is a differentiable function defined on M × [ 0 , ) . We suppose that the Bakry-Émery curvature and the N -dimensional Bakry-Émery curvature are bounded from below, respectively. Then we obtain the gradient estimate of Li-Yau type for the above general heat equation. Our results generalize the work of Huang-Ma ([4]) and Y. Li ([6]), recently. ...

Heat kernel estimates for the Dirichlet fractional Laplacian

Zhen-Qing Chen, Panki Kim, Renming Song (2010)

Journal of the European Mathematical Society

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We consider the fractional Laplacian - ( - Δ ) α / 2 on an open subset in d with zero exterior condition. We establish sharp two-sided estimates for the heat kernel of such a Dirichlet fractional Laplacian in C 1 , 1 open sets. This heat kernel is also the transition density of a rotationally symmetric α -stable process killed upon leaving a C 1 , 1 open set. Our results are the first sharp twosided estimates for the Dirichlet heat kernel of a non-local operator on open sets.

Observability inequalities and measurable sets

Jone Apraiz, Luis Escauriaza, Gengsheng Wang, C. Zhang (2014)

Journal of the European Mathematical Society

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This paper presents two observability inequalities for the heat equation over Ω × ( 0 , T ) . In the first one, the observation is from a subset of positive measure in Ω × ( 0 , T ) , while in the second, the observation is from a subset of positive surface measure on Ω × ( 0 , T ) . It also proves the Lebeau-Robbiano spectral inequality when Ω is a bounded Lipschitz and locally star-shaped domain. Some applications for the above-mentioned observability inequalities are provided.

Radial Heat Diffusion from the Root of a Homogeneous Tree and the Combinatorics of Paths

Joel M. Cohen, Mauro Pagliacci, Massimo A. Picardello (2008)

Bollettino dell'Unione Matematica Italiana

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We compute recursively the heat semigroup in a rooted homogeneous tree for the diffusion with radial (with respect to the root) but non-isotropic transition probabilities. This is the discrete analogue of the heat operator on the disc given by Δ + c r for some constant c that represents a drift towards (or away from) the origin.

Initial measures for the stochastic heat equation

Daniel Conus, Mathew Joseph, Davar Khoshnevisan, Shang-Yuan Shiu (2014)

Annales de l'I.H.P. Probabilités et statistiques

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We consider a family of nonlinear stochastic heat equations of the form t u = u + σ ( u ) W ˙ , where W ˙ denotes space–time white noise, the generator of a symmetric Lévy process on 𝐑 , and σ is Lipschitz continuous and zero at 0. We show that this stochastic PDE has a random-field solution for every finite initial measure u 0 . Tight a priori bounds on the moments of the solution are also obtained. In the particular case that f = c f ' ' for some c g t ; 0 , we prove that if u 0 is a finite measure of compact support, then the...

Nonanalyticity of solutions to t u = ² x u + u ²

Grzegorz Łysik (2003)

Colloquium Mathematicae

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It is proved that the solution to the initial value problem t u = ² x u + u ² , u(0,x) = 1/(1+x²), does not belong to the Gevrey class G s in time for 0 ≤ s < 1. The proof is based on an estimation of a double sum of products of binomial coefficients.

Modelling of multicomponent diffusive phase transformation in solids

Vala, Jiří

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Physical analysis of phase transformation of materials consisting from several (both substitutional and interstitial) components, coming from the Onsager extremal thermodynamic principle, leads, from the mathematical point of view, to a system of partial differential equations of evolution type, including certain integral term, with substantial differences in particular phases ( α , γ ) and in moving interface of finite thickness ( β ), in whose center the ideal liquid material behaviour...

Property C for ODE and Applications to an Inverse Problem for a Heat Equation

A. G. Ramm (2009)

Bulletin of the Polish Academy of Sciences. Mathematics

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Let j : = - d ² / d x ² + k ² q j ( x ) , k = const > 0, j = 1,2, 0 < e s s i n f q j ( x ) e s s s u p q j ( x ) < . Suppose that (*) 0 1 p ( x ) u ( x , k ) u ( x , k ) d x = 0 for all k > 0, where p is an arbitrary fixed bounded piecewise-analytic function on [0,1], which changes sign finitely many times, and u j solves the problem j u j = 0 , 0 ≤ x ≤ 1, u j ' ( 0 , k ) = 0 , u j ( 0 , k ) = 1 . It is proved that (*) implies p = 0. This result is applied to an inverse problem for a heat equation.

Hardy's theorem for the helgason Fourier transform on noncompact rank one symmetric spaces

S. Thangavelu (2002)

Colloquium Mathematicae

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Let G be a semisimple Lie group with Iwasawa decomposition G = KAN. Let X = G/K be the associated symmetric space and assume that X is of rank one. Let M be the centraliser of A in K and consider an orthonormal basis Y δ , j : δ K ̂ , 1 j d δ of L²(K/M) consisting of K-finite functions of type δ on K/M. For a function f on X let f̃(λ,b), λ ∈ ℂ, be the Helgason Fourier transform. Let h t be the heat kernel associated to the Laplace-Beltrami operator and let Q δ ( i λ + ϱ ) be the Kostant polynomials. We establish the following...