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51.
Popp and Yan [F.A. Popp, Y. Yan, Phys. Lett. A 293 (2002) 93] proposed a model for delayed luminescence based on a single time-dependent coherent state. We show that the general solution of their model corresponds to a luminescence that is a linear function of time. Therefore, their model is not compatible with experimental delayed luminescence. Moreover, the functions that they use to describe the oscillatory behaviour of delayed luminescence are not solutions of the coupling equations to be solved. 相似文献
52.
In this note we show how to include low order terms in the C∞ well-posedness results for weakly hyperbolic equations with analytic time-dependent coefficients. This is achieved by doing a different reduction to a system from the previously used one. We find the Levi conditions such that the C∞ well-posedness continues to hold. 相似文献
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54.
José A. Gálvez Antonio Martínez José L. Teruel 《Journal of Mathematical Analysis and Applications》2014
The paper deals with the study of complete embedded flat surfaces in H3 with a finite number of isolated singularities. We give a detailed information about its topology, conformal type and metric properties. We show how to solve the generalized Weyl?s problem of realizing isometrically any complete flat metric with Euclidean singularities in H3 which gives the existence of complete embedded flat surfaces with a finite arbitrary number of isolated singularities. 相似文献
55.
David Ariza-Ruiz Chong Li Genaro López-Acedo 《Journal of Mathematical Analysis and Applications》2014
We give a direct proof of Schauder's fixed point theorem in the setting of geodesic metric spaces, generalizing the classical Schauder's theorem and improving a recent version of this theorem in CAT(κ) spaces. As an application we prove an existence result for a variational inequality in the setting of CAT(κ) spaces. 相似文献
56.
We show that every finite volume hyperbolic manifold of dimension greater than or equal to 3 is stable under rescaled Ricci flow, i.e. that every small perturbation of the hyperbolic metric flows back to the hyperbolic metric again. Note that we do not need to make any decay assumptions on this perturbation. 相似文献
57.
Arising from the proposed Transmission Line(TL) model for ERR and wire structure, a TL model for a metamaterial absorber is proposed. The S-parameters obtained by this TL model demonstrate the same shapes as the simulation. An investigation of the TL model and average absorption power densities shows that the metamaterial absorber does not simply convert the electromagnetic wave into thermal energy, but concentrate the electromagnetic wave into a small space where it is finally absorbed. This suggests that ... 相似文献
58.
《代数通讯》2013,41(11):5361-5376
Abstract We prove that when a countable group admits a nontrivial Floyd-type boundary, then every nonelementary and metrically proper subgroup contains a noncommutative free subgroup. This generalizes the corresponding well-known results for hyperbolic groups and groups with infinitely many ends. It also shows that no finitely generated amenable group admits a nontrivial boundary of this type. This improves on a theorem by Floyd (Floyd, W. J. (1980). Group completions and limit sets of Kleinian groups. Invent. Math. 57: 205–218) as well as giving an elementary proof of a conjecture stated in that same paper. We also show that if the Floyd boundary of a finitely generated group is nontrivial, then it is a boundary in the sense of Furstenberg and the group acts on it as a convergence group. 相似文献
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