Exploració per autor "Delshams Valdés, Amadeu"
Ara es mostren els items 50-69 de 86
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KAM theory and a partial justification of Greene's criterion for non-twist maps
Delshams Valdés, Amadeu; Llave Canosa, Rafael de la (1999)
Article
Accés obertWe consider perturbations of integrable area preserving non twist maps of the annulus those are maps in which the twist condition changes sign These maps appear in a variety of applications notably transport in atmospheric ... -
Lower and upper bounds for the splitting of separatrices of the pendulum under a fast quasiperiodic forcing
Delshams Valdés, Amadeu; Gelfreich, Vassili; Jorba, Angel; Martínez-Seara Alonso, M. Teresa (1997)
Article
Accés obertQuasiperiodic perturbations with two frequencies $(1/\varepsilon ,\gamma /\varepsilon )$ of a pendulum are considered, where $\gamma $ is the golden mean number. We study the splitting of the three-dimensional invariant ... -
Melnikov potential for exact symplectic maps
Delshams Valdés, Amadeu; Ramírez Ros, Rafael (1997)
Article
Accés obertThe splitting of separatrices of hyperbolic fixed points for exact symplectic maps of $n$ degrees of freedom is considered. The non-degenerate critical points of a real-valued function (called the Melnikov potential) are ... -
Mixed dynamics in reversible maps with gure-8 homoclinic connections
Delshams Valdés, Amadeu; Gonchenko, Sergey; Lázaro Ochoa, José Tomás (2014)
Text en actes de congrés
Accés obertWe study dynamics and bifurcations of two-dimensional reversible maps having non-transversal heteroclinic cycles containing symmetric saddle periodic points. We consider one-parameter families of rev ersible maps unfolding ... -
Mixed dynamics of two-dimensional reversible maps with a symmetric couple of quadratic homoclinic tangencies
Lázaro Ochoa, José Tomás; Delshams Valdés, Amadeu; Gonchenko, Marina; Gonchenko, Sergey (American Institute of Mathematical Sciences, 2018-09)
Article
Accés obertWe study dynamics and bifurcations of 2-dimensional reversible maps having a symmetric saddle fixed point with an asymmetric pair of nontransversal homoclinic orbits (a symmetric nontransversal homoclinic figure-8). We ... -
On bifurcations of area-preserving and nonorientable maps with quadratic homoclinic tangencies
Delshams Valdés, Amadeu; Gonchenko, Marina (Springer, 2014)
Article
Accés obertWe study bifurcations of nonorientable area-preserving maps with quadratic homoclinic tangencies. We study the case when the maps are given on nonorientable two-dimensional surfaces. We consider one- and two-parameter ... -
On bifurcations of homoclinic tangencies in area-preserving maps on non-orientable manifolds
Delshams Valdés, Amadeu; Gonchenko, Marina; Gonchenko, Sergey (Springer, 2016)
Capítol de llibre
Accés restringit per política de l'editorialWe study bifurcations of non-orientable area-preserving maps with quadratic homoclinic tangencies. We study the case when the maps are given on non-orientable two-dimensional manifolds. We consider one and two parameter ... -
On Birkhoff's conjecture about convex billiards
Delshams Valdés, Amadeu; Ramírez Ros, Rafael (1995)
Article
Accés obertBirkhoff conjectured that the elliptic billiard was the only integrable convex billiard. Here we prove a local version of this conjecture: any non-trivial symmetric entire perturbation of an elliptic billiard is non-integrable. -
On dynamics and bifurcations of area-preserving maps with homoclinic tangencies
Delshams Valdés, Amadeu; Gonchenko, Marina; Gonchenko, Sergey V. (2015-09-01)
Article
Accés obertWe study bifurcations of area-preserving maps, both orientable (symplectic) and non-orientable, with quadratic homoclinic tangencies. We consider one and two parameter general unfoldings and establish results related to ... -
On the scattering map and homoclinic connections between Lyapunov orbits
Cancalias Vila, Elisabet; Delshams Valdés, Amadeu; Masdemont Soler, Josep; Roldán González, Pablo (2005-09)
Comunicació de congrés
Accés obertHomoclinic and heteroclinic connections between planar Lyapunov orbits of the Sun-Earth and Earth-Moon models can be found by using their hyperbolic invariant manifolds and Poincare section representations. These connections ... -
Orbits of unbounded energy in quasi-periodic perturbations of geodesic flows
Delshams Valdés, Amadeu; Llave Canosa, Rafael de la; Martínez-Seara Alonso, M. Teresa (2003)
Article
Accés obertWe show that certain mechanical systems, including a geodesic °ow in any dimension plus a quasi-periodic perturbation by a potential, have orbits of unbounded energy. The assumptions we make in the case of geodesic °ows ... -
Persistence of homoclinic orbits for billiards and twist maps
Bolotin, S.; Delshams Valdés, Amadeu; Ramírez Ros, Rafael (2003)
Article
Accés obertWe consider the billiard motion inside a C2-small perturbation of a ndimensional ellipsoid Q with a unique major axis. The diameter of the ellipsoid Q is a hyperbolic two-periodic trajectory whose stable and unstable ... -
Poincaré-Melnikov-Arnold method for analytic planar maps
Delshams Valdés, Amadeu; Ramírez Ros, Rafael (1995)
Article
Accés obertThe Poincare-Melnikov-Arnold method for planar maps gives rise to a Melnikov function defined by an infinite and (a priori) analytically uncomputable sum. Under an assumption of meromorphicity, residues theory can be ... -
Poincaré-Melnikov-Arnold method for twist maps
Delshams Valdés, Amadeu; Ramírez Ros, Rafael (1997)
Article
Accés obertThe Poincar\'e--Melnikov--Arnold method is the standard tool for detecting splitting of invariant manifolds for systems of ordinary differential equations close to ``integrable'' ones with associated separatrices. This ... -
Preface of Llavefest: A broad perspective on finite and infinite dimensional dynamical systems
Cabré Vilagut, Xavier; Delshams Valdés, Amadeu; Gidea, Marian; Zeng, Chongchun (American Institute of Mathematical Sciences, 2018-12-01)
Article
Accés obertWe prove that for any non-trivial perturbation depending on any two independent harmonics of a pendulum and a rotor there is global instability. The proof is based on the geometrical method and relies on the concrete ... -
Pseudo-normal form near saddle-center or saddle-focus equilibria
Delshams Valdés, Amadeu; Lázaro Ochoa, José Tomás (2003)
Article
Accés obertIn this paper we introduce the pseudo-normal form, which generalizes the notion of normal form around an equilibrium. Its convergence is proved for a general analytic system in a neighborhood of a saddle-center or a ... -
Pseudo-normal forms and their applications
Delshams Valdés, Amadeu; Lázaro Ochoa, José Tomás (2001)
Article
Accés obert -
Psi-series of quadratic vector fields on the plane
Delshams Valdés, Amadeu; Mir, Arnau (1997)
Article
Accés obertPsi-series (i.e., logarithmic series) for the solutions of quadratic vector fields on the plane are considered. Its existence and convergence is studied, and an algorithm for the location of logarithmic singularities is ... -
Psi-series, singularities of solutions and integrability of polynomial systems
Mir, Arnau; Delshams Valdés, Amadeu (1996)
Article
Accés obertPsi-series (i.e., logarithmic series) of $m$-dimensional polynomial systems are considered. Its existence and convergence is studied, and an algorithm of location of logarithmic singularities is developed. Moreover, ... -
Quasiperiodic perturbations of heteroclinic attractor networks
Delshams Valdés, Amadeu; Guillamon Grabolosa, Antoni; Huguet Casades, Gemma (Institute of Physics (IOP), 2018-10-01)
Article
Accés obertWe consider heteroclinic attractor networks motivated by models of competition between neural populations during binocular rivalry. We show that gamma distributions of dominance times observed experimentally in binocular ...