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Quasi-similarity of contractions having 2 x 2 a singular characteristic function
(Elsevier, 2008)
LetT1:H1→H1be a completely non-unitary contraction having a 2×2 singular characteristic function Θ1; thatis, Θ1=[θi,j]i, j=1,2withθij∈H∞and det(Θ1)=0. Asit is well known, Θ1is a singular matrix if and only ifΘ1can be written ...
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Artículo
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Bifurcation behavior of a superlattice model
(Society for Industrial and Applied Mathematics, 2006)
We present a complete description of the stationary and dynamical behavior of semiconductor superlattices in the framework of a discrete drift model by means of numerical continuation, singular perturbation analysis, and ...
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The Postprocessed Mixed Finite-Element Method for the Navier–Stokes Equations: Refined Error Bounds
(Society for Industrial and Applied Mathematics, 2007)
A postprocessing technique for mixed finite-element methods for the incompressible Navier–Stokes equations is analyzed. The postprocess, which amounts to solving a (linear) Stokes problem, is shown to increase the order ...
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On Pták's generalization of Hankel operators
(Springer, 2001)
In 1997 Pták defined generalized Hankel operators as follows: Given two contractions T1 ∈ B(H1) and T2 ∈ B(H2), an operator X: H1 → H2 is said to be a generalized Hankel operator if T2X = XT ∗ 1 and X satisfies a ...
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Postprocessing finite-element methods for the Navier–Stokes Equations: the Fully discrete case
(Society for Industrial and Applied Mathematics, 2008)
An accuracy-enhancing postprocessing technique for finite-element discretizations of the Navier–Stokes equations is analyzed. The technique had been previously analyzed only for semidiscretizations, and fully discrete ...
Artículo
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Analysis of an age-structured predator-prey model with disease in the prey
(Elsevier, 2006-09)
We study a nonlinear predator-prey model in which the prey population is affected by a mild disease, but has an effect on the death-rate and is assumed to have age structure. We assume that the predator population grows ...
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Existence of a Reversible T-Point Heteroclinic Cycle in a Piecewise Linear Version of the Michelson System
(Society for Industrial and Applied Mathematics, 2008)
The proof of the existence of a global connection in differential systems is generally a difficult task. Some authors use numerical techniques to show this existence, even in the case of continuous piecewise linear systems. ...
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Bifurcación Silla-Nodo de Conos Invariantes en sistemas lineales a trozos Vía Bifurcación Foco-Centro-Ciclo Límite
(Sema, 2008)
En este trabajo se considera la existencia de conos invariantes en sistemas dinámicos continuos tridimensionales lineales a trozos, dada la relevancia que estas variedades invariantes tienen en la determinación de la ...
Artículo
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Fixed points and boundary behaviour of the Koenigs function
(2004)
We analyze the relationship between the fixed points of different iterates of an analytic self-map of the unit disk. We show that, in general, a boundary fixed point of such a function is not a fixed point of its iterates. ...