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Using the Unified Transform, also known as the Fokas method, the solution of the sine-Gordon equation in the quarter plane can be expressed in terms of the solution of a matrix Riemann–Hilbert problem whose definition involves four spectral functions . The functions and are defined via a nonlinear Fourier transform of the initial data, whereas and are defined via a nonlinear Fourier transform of the boundary values. In this paper, we provide an extensive study of these nonlinear Fourier transforms and the associated eigenfunctions under weak regularity and decay assumptions on the initial and boundary values. The results can be used to determine the long-time asymptotics of the sine-Gordon quarter-plane solution via nonlinear steepest descent techniques. 相似文献
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Kaouther Ammar 《Comptes Rendus Mathematique》2006,343(9):569-572
In this Note, we study the ‘triply’ degenerate problem: on , on Ω and ‘on some part of the boundary’ , in the case of continuous nonhomogenous and nonstationary boundary data a. The functions are assumed to be continuous nondecreasing and to verify the normalisation condition and the range condition . Using monotonicity and penalization methods, we prove existence of a weak entropy solution in the spirit of F. Otto (1996). To cite this article: K. Ammar, C. R. Acad. Sci. Paris, Ser. I 343 (2006). 相似文献
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Given , a compact connected Riemannian manifold of dimension , with boundary ?M, we consider an initial boundary value problem for a fractional diffusion equation on , , with time-fractional Caputo derivative of order . We prove uniqueness in the inverse problem of determining the smooth manifold (up to an isometry), and various time-independent smooth coefficients appearing in this equation, from measurements of the solutions on a subset of ?M at fixed time. In the “flat” case where M is a compact subset of , two out the three coefficients ρ (density), a (conductivity) and q (potential) appearing in the equation on are recovered simultaneously. 相似文献
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In a Hilbert space setting, we study the asymptotic behavior, as time t goes to infinity, of the trajectories of a second-order differential equation governed by the Yosida regularization of a maximally monotone operator with time-varying positive index . The dissipative and convergence properties are attached to the presence of a viscous damping term with positive coefficient . A suitable tuning of the parameters and makes it possible to prove the weak convergence of the trajectories towards zeros of the operator. When the operator is the subdifferential of a closed convex proper function, we estimate the rate of convergence of the values. These results are in line with the recent articles by Attouch–Cabot [3], and Attouch–Peypouquet [8]. In this last paper, the authors considered the case , which is naturally linked to Nesterov's accelerated method. We unify, and often improve the results already present in the literature. 相似文献
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Zhijun Zhang 《Journal of Differential Equations》2018,264(1):263-296
In this paper, we obtain conditions about the existence and boundary behavior of (strictly) convex solutions to the Monge–Ampère equations with boundary blow-up and where Ω is a strictly convex, bounded smooth domain in with , (or ), which is positive in Ω, but may vanish or blow up on the boundary, , , and f is strictly increasing on (or , , and f is strictly increasing on ). 相似文献
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We study the initial-boundary-value problem for the Camassa–Holm equation on the half-line by associating to it a matrix Riemann–Hilbert problem in the complex k-plane; the jump matrix is determined in terms of the spectral functions corresponding to the initial and boundary values. We prove that if the boundary values are ?0 for all t then the corresponding initial-boundary-value problem has a unique solution, which can be expressed in terms of the solution of the associated RH problem. In the case , the compatibility of the initial and boundary data is explicitly expressed in terms of an algebraic relation to be satisfied by the spectral functions. To cite this article: A. Boutet de Monvel, D. Shepelsky, C. R. Acad. Sci. Paris, Ser. I 341 (2005). 相似文献
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Fritz Gesztesy Lance L. Littlejohn Isaac Michael Richard Wellman 《Journal of Differential Equations》2018,264(4):2761-2801
In 1961, Birman proved a sequence of inequalities , for , valid for functions in . In particular, is the classical (integral) Hardy inequality and is the well-known Rellich inequality. In this paper, we give a proof of this sequence of inequalities valid on a certain Hilbert space of functions defined on . Moreover, implies ; as a consequence of this inclusion, we see that the classical Hardy inequality implies each of the inequalities in Birman's sequence. We also show that for any finite , these inequalities hold on the standard Sobolev space . Furthermore, in all cases, the Birman constants in these inequalities are sharp and the only function that gives equality in any of these inequalities is the trivial function in (resp., ). We also show that these Birman constants are related to the norm of a generalized continuous Cesàro averaging operator whose spectral properties we determine in detail. 相似文献
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《Nonlinear Analysis: Theory, Methods & Applications》2005,62(6):1091-1107
In this paper, we study the nonlinear initial–boundary Riemann problem and the generalized nonlinear initial–boundary Riemann problem for quasilinear hyperbolic systems of conservation laws with nonlinear boundary conditions on the domain . Under the assumption that each positive eigenvalue is either linearly degenerate or genuinely nonlinear, we get the existence and uniqueness of the self-similar solution to the nonlinear initial–boundary Riemann problem and of the global piecewise solution containing only shocks and (or) contact discontinuities to the corresponding generalized nonlinear initial–boundary Riemann problem. It shows that the self-similar solution to the nonlinear initial–boundary Riemann problem possesses the global structural stability. 相似文献
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