共查询到20条相似文献,搜索用时 15 毫秒
1.
Nicola Visciglia 《Comptes Rendus Mathematique》2004,338(1):27-30
In this paper we prove a global well-posedness result for the following Cauchy problem: where the initial data are compactly supported, 1?α<5, , . To cite this article: N. Visciglia, C. R. Acad. Sci. Paris, Ser. I 338 (2004). 相似文献
2.
Frédéric Déglise 《Comptes Rendus Mathematique》2004,338(1):41-46
Following Voevodsky, one can associate a Gysin triangle in the category of triangulated motives to every couple (X,Z) such that X is a smooth scheme and Z is a smooth closed subscheme of X. We study the functoriality of this triangle: if one considers a morphism which is transversal to Z, this functoriality is simple. We are rather interested in the case where f is not quite transversal to Z. In that case, one obtains a motivic excess intersection formula and a ramification formula in the sense of equicharacteristic discrete valuation rings. To cite this article: F. Déglise, C. R. Acad. Sci. Paris, Ser. I 338 (2004). 相似文献
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We consider a composite material constituted of carbon or glass fibres included in a resin which becomes solid when it is heated up (reaction of reticulation). The mathematical modelling of the cure process is given by a kinetic equation describing the evolution of the reaction of reticulation coupled with the heat equation. The geometry of the composite material is periodic, with a small period . First we prove the existence and uniqueness of a solution by using Schauder's fixed point theorem. Then, by using an asymptotic expansion, we derive the homogenized problem which describes the macroscopic behaviour of the material. We prove the convergence of the solution of the problem to the solution of the homogenized problem when ? tends to zero and we obtain an error estimate in a case of weak non-linearity. Finally we solve numerically the homogenized problem. To cite this article: S. Meliani et al., C. R. Acad. Sci. Paris, Ser. I 339 (2004). 相似文献
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We present in this note a posteriori error estimates based on the postprocessing technique for the reduced model of flow in fractured porous media, introduced and analysed by V. Martin, J. Jaffré, and J. Roberts. This model is approximated by the Raviart–Thomas finite elements of lowest order. In this type of approximation, the velocity is well approximated. A postprocessing of the pressure appears to be necessary since it does not belong to . We give an upper bound for the error in the energy norm, with some indicators that are expressed in terms of the reconstruction of the pressure. Numerical results show that all indicators converge to zero when the mesh size goes to zero, with the same speed as the error. One of these indicators can be interpreted as both a discretization indicator and an indicator of the reduced model validity. 相似文献
6.
Stéphane Fischler 《Comptes Rendus Mathematique》2004,339(10):679-682
Let be the exponent that measures how a non-quadratic real number ξ and its square can be simultaneously approximated by rational numbers with the same denominator. Davenport and Schmidt have proved that is always between the golden ratio γ and 2. Roy, and after him Bugeaud and Laurent, have constructed numbers ξ such that . Their method involves infinite words with many palindrome prefixes. In this text, we define new exponents of approximation that allow us to obtain, to some extent, a characterization of the values obtained by these authors. To cite this article: S. Fischler, C. R. Acad. Sci. Paris, Ser. I 339 (2004). 相似文献
7.
Dan Popovici 《Comptes Rendus Mathematique》2004,338(2):151-156
Let be a bounded pseudoconvex open set and let ? be a plurisubharmonic function on For every positive integer m, we consider the multiplier ideal sheaf and the Hilbert space of holomorphic functions f on such that is integrable on We give an effective version, with estimates, of Nadel's result stating that the sheaf is coherent and generated by an arbitrary orthonormal basis of This result is expected to play a major part in the context of current regularizations with estimates of the Monge–Ampère masses. To cite this article: D. Popovici, C. R. Acad. Sci. Paris, Ser. I 338 (2004). 相似文献
8.
Pierre Germain 《Comptes Rendus Mathematique》2005,340(7):547-550
We study in this Note the solutions of the 2D Navier–Stokes equations with initial data in ?BMO. For in the closure of the Schwartz class, we obtain the existence and uniqueness of a global solution, and besides an estimate on its norm in ?BMO. To cite this article: P. Germain, C. R. Acad. Sci. Paris, Ser. I 340 (2005). 相似文献
9.
Let g be a locally Lipschitz continuous function defined on . We assume that g satisfies the Keller–Osserman condition and there exists a positive real number a such that g is convex on . Then any solution u of in a ball B of , , which tends to infinity on ?B, is spherically symmetric. To cite this article: A. Porretta, L. Véron, C. R. Acad. Sci. Paris, Ser. I 342 (2006). 相似文献
10.
We consider a real Gaussian process X with unknown smoothness where the mean-square derivative is supposed to be Hölder continuous in quadratic mean. First, from the discrete observations , we study reconstruction of , , with , a piecewise polynomial interpolation of degree . We show that the mean-square error of interpolation is a decreasing function of r but becomes stable as soon as . Next, from an interpolation-based empirical criterion, we derive an estimator of and prove its strong consistency by giving an exponential inequality for . Finally, we prove the strong convergence of toward with a similar rate as in the case ‘ known’. To cite this article: D. Blanke, C. Vial, C. R. Acad. Sci. Paris, Ser. I 343 (2006). 相似文献
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Aicha Henien Larbi Ait-Hennani Jacques Demongeot Ali Laksaci Mustapha Rachdi 《Comptes Rendus Mathematique》2018,356(5):571-574
We present in this paper a consistent nonparametric test for heteroscedasticity when data are of functional kind. The latter is constructed by evaluating the difference between the conditional and unconditional variances. We show the asymptotic normality of the statistical test under the null hypothesis. In addition, we prove that this test is consistent against all deviations from homoscedasticity condition. 相似文献
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We construct an associative product on the symmetric module of any pre-Lie algebra L. It turns into a Hopf algebra which is isomorphic to the envelopping algebra of . Then we prove that in the case of rooted trees our construction is dual to that of Connes and Kreimer. We also show that symmetric brace algebras and pre-Lie algebras are the same. Finally, we give a similar interpretation of the Hopf algebra of planar rooted trees. To cite this article: J.-M. Oudom, D. Guin, C. R. Acad. Sci. Paris, Ser. I 340 (2005). 相似文献
13.
Sana Hadj Amor 《Comptes Rendus Mathematique》2006,343(6):423-426
We prove two results on the density of states of the discrete one dimensional quasi-periodic Schrödinger equation with an analytic potential and Diophantine frequencies in the perturbed regime. On the one hand, we prove that this function has the behavior of a Hölder- function. On the other, we show that the length of the gaps has a sub-exponential estimate which depends on its label given by the gap-labeling theorem. To cite this article: S. Hadj Amor, C. R. Acad. Sci. Paris, Ser. I 343 (2006). 相似文献
14.
Bruno Demange 《Comptes Rendus Mathematique》2005,340(10):709-714
The uncertainty principle states that a nonzero function and its Fourier transform cannot be both sharply localized. It is well known that the support and the spectrum of a function cannot both have finite measure. In Shubin et al. [Geom. Funct. Anal. 8 (1998) 932–964], it is shown that they cannot be contained in ?-thin sets E and . We give here other examples of sets E and having this property. The thinness of the sets is expressed in terms of a dyadic decomposition of the space, which is related to the functions on . These sets are not ?-thin in general. We prove that the pairs of sets we consider are strongly annihilating in the sense of Havin and Jöricke. To cite this article: B. Demange, C. R. Acad. Sci. Paris, Ser. I 340 (2005). 相似文献
15.
Alberto Arabia 《Comptes Rendus Mathematique》2004,338(4):267-270
Recent works are devoted to the rational smoothness of varieties of representations for quivers, notably those of Robert Bédard, Ralf Schiffler and Philippe Caldéro. Their main result is the equivalence for a variety of representations of a quiver of Dynkin type, between This Note gives a different approach to the question and a strengthened version of Bédard–Schiffler–Caldéro's equivalences. To cite this article: A. Arabia, C. R. Acad. Sci. Paris, Ser. I 338 (2004). 相似文献
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Fateh Chebana 《Comptes Rendus Mathematique》2004,338(4):311-316
The goal of this work is to establish the limit distribution of the process where is a class of weight functions W, fn is the kernel density estimator of the density f and A is a Borelian subset of . We apply this result to derive new statistics to test goodness-of-fit of the density function f. Under some local alternatives, these new tests are more powerful than the usual Bickel–Rosenblatt one. To cite this article: F. Chebana, C. R. Acad. Sci. Paris, Ser. I 338 (2004). 相似文献
18.
Let dk,?(n) be the function number of divisors of the integer n?1, in arithmetic progressions {?+mk}, with 1???k and ?,k coprime, and let F(n;k,?) defined as follows: In this Note, we study and give the structure of dk,?-superior, highly composite numbers, which generalize those defined by S. Ramanujan. We prove that F(n;k,?) reaches its maximum among these numbers. We give it explicitly for k=2,…,13. This generalizes the study of Nicolas and Robin, in which the case k=1 is treated. To cite this article: A. Derbal, A. Smati, C. R. Acad. Sci. Paris, Ser. I 339 (2004). 相似文献
19.
Samy Skander Bahoura 《Comptes Rendus Mathematique》2005,341(1):25-28
We prove some a priori estimates in dimension for equations of type prescribed scalar curvature. In the particular case of the unit sphere we give an estimation of the constant c in the inequality . To cite this article: S. Skander Bahoura, C. R. Acad. Sci. Paris, Ser. I 341 (2005). 相似文献
20.
Dominique Vieugué 《Comptes Rendus Mathematique》2004,339(9):631-636
In this Note, we prove, in the p-adic case, a 0–1 law about the linearization of families under a polynomial perturbation in t. This gives new examples of non linearizable functions in the p-adic case. To cite this article: D. Vieugué, C. R. Acad. Sci. Paris, Ser. I 339 (2004). 相似文献