共查询到20条相似文献,搜索用时 16 毫秒
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M. Tidriri 《Journal of statistical physics》2001,104(1-2):255-290
In this paper we derive rigorously the coupling of kinetic equations and their hydrodynamic limits for a simplified kinetic model. We prove the global convergence of the Chapman–Enskog expansion for this model. We then study the existence theory and asymptotic behaviour of the coupled systems. To solve the coupled problems we propose to use the transmission time marching algorithm. We then develop a convergence theory for the resulting algorithms. 相似文献
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《Journal of Nonlinear Mathematical Physics》2013,20(1-2):219-225
Abstract The Hilbert space representations of a class of commutation relations associated with a Möbius transformation is studied using results on convergence of continued fractions. 相似文献
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Maria João M. Vasconcelos Sandra M. Rua Ventura Diamantino Rui S. Freitas João Manuel R.S. Tavares 《Journal of voice》2011,25(6):732-742
Over the last few decades, researchers have been investigating the mechanisms involved in speech production. Image analysis can be a valuable aid in the understanding of the morphology of the vocal tract. The application of magnetic resonance imaging to study these mechanisms has been proven to be reliable and safe. We have applied deformable models in magnetic resonance images to conduct an automatic study of the vocal tract; mainly, to evaluate the shape of the vocal tract in the articulation of some European Portuguese sounds, and then to successfully automatically segment the vocal tract's shape in new images. Thus, a point distribution model has been built from a set of magnetic resonance images acquired during artificially sustained articulations of 21 sounds, which successfully extracts the main characteristics of the movements of the vocal tract. The combination of that statistical shape model with the gray levels of its points is subsequently used to build active shape models and active appearance models. Those models have then been used to segment the modeled vocal tract into new images in a successful and automatic manner. The computational models have thus been revealed to be useful for the specific area of speech simulation and rehabilitation, namely to simulate and recognize the compensatory movements of the articulators during speech production. 相似文献
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ExperimentalInvestigationoftheNonlinearCouplingStrengthofaPhotorefractiveCrystalExperimentalInvestigationoftheNonlinearCoupli... 相似文献
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A question of some interest in computational statistical mechanics is whether macroscopic quantities can be accurately computed without detailed resolution of the fastest scales in the problem. To address this question a simple model for a distinguished particle immersed in a heat bath is studied (due to Ford and Kac). The model yields a Hamiltonian system of dimension 2N+2 for the distinguished particle and the degrees of freedom describing the bath. It is proven that, in the limit of an infinite number of particles in the heat bath (N), the motion of the distinguished particle is governed by a stochastic differential equation (SDE) of dimension 2. Numerical experiments are then conducted on the Hamiltonian system of dimension 2N+2 (N1) to investigate whether the motion of the distinguished particle is accurately computed (i.e., whether it is close to the solution of the SDE) when the time step is small relative to the natural time scale of the distinguished particle, but the product of the fastest frequency in the heat bath and the time step is not small—the underresolved regime in which many computations are performed. It is shown that certain methods accurately compute the limiting behavior of the distinguished particle, while others do not. Those that do not are shown to compute a different, incorrect, macroscopic limit. 相似文献
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T. R. Cardoso L. B. Castro A. S. de Castro 《International Journal of Theoretical Physics》2010,49(1):10-17
The Duffin-Kemmer-Petiau formalism with vector and scalar potentials is used to point out a few misconceptions diffused in
the literature. It is explicitly shown that the scalar coupling makes the DKP formalism not equivalent to the Klein-Gordon
formalism or to the Proca formalism, and that the spin-1 sector of the DKP theory looks formally like the spin-0 sector. With
proper boundary conditions, scattering of massive bosons in an arbitrary mixed vector-scalar square step potential is explored
in a simple way and effects due to the scalar coupling on the particle-antiparticle production and localization of bosons
are analyzed in some detail. 相似文献
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Margherita Disertori Franz Merkl Silke W. W. Rolles 《Communications in Mathematical Physics》2014,332(2):783-825
We study a lattice sigma model which is expected to reflect Anderson localization and delocalization transition for real symmetric band matrices in 3D, but describes the mixing measure for a vertex reinforced jump process too. For this model we prove exponential localization at any temperature in a strip, and more generally in any quasi-one dimensional graph, with pinning (mass) at only one site. The proof uses a Mermin–Wagner type argument and a transfer operator approach. 相似文献