Exploració per autor "Delshams Valdés, Amadeu"
Ara es mostren els items 1-20 de 85
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A geometric approach to the existence of orbits with unbounded energy in generic periodic perturbations by a potential of generic geodesic flows of T<sup>2</sup>
Delshams Valdés, Amadeu; Llave Canosa, Rafael de la; Martínez-Seara Alonso, M. Teresa (1999)
Article
Accés obertWe give a proof based in geometric perturbation theory of a result proved by J.N. Mather using variational methods. Namely, the existence of orbits with unbounded energy in perturbations of a generic geodesic flow in T^2 ... -
A geometric mechanism for diffusion in Hamiltonian systems overcoming the large gap problem: heuristics and rigorous verification on a model.
Delshams Valdés, Amadeu; Llave Canosa, Rafael de la; Martínez-Seara Alonso, M. Teresa (2003)
Article
Accés obertWe introduce a geometric mechanism for di?usion in a priori unstable nearly integrable dynamical systems. It is based on the observation that resonances, besides destroying the primary KAM tori, create secondary tori and ... -
A geometric mechanism for diffusion in Hamiltonian systems overcoming the large gap problem: Announcement of results
Delshams Valdés, Amadeu; Llave Canosa, Rafael de la; Martínez-Seara Alonso, M. Teresa (2003)
Article
Accés obertWe present a geometric mechanism for diffusion in Hamiltonian systems. We also present tools that allow to verify it in a concrete model. In particular, we verify it in a system which presents the large gap problem. -
A geometric mechanism of diffusion: Rigorous verification in a priori unstable Hamiltonian systems
Delshams Valdés, Amadeu; Huguet Casades, Gemma (2010-07)
Report de recerca
Accés obertIn this paper we consider a representative a priori unstable Hamiltonian system with 2 + 1/2 degrees of freedom, to which we apply the geometric mechanism for diffusion introduced in the paper Delshams et al., Mem. Amer. ... -
A geometric mechanism of diffusion: rigorous verification in a priori unstable Hamiltonian systems
Delshams Valdés, Amadeu; Huguet Casades, Gemma (2011-03-01)
Article
Accés restringit per política de l'editorialIn this paper we consider a representative a priori unstable Hamiltonian system with 2 + 1/2 degrees of freedom and we apply the geometric mechanism for diffusion introduced in [A. Delshams, R. de la Llave, T.M. Seara, ... -
A methodology for obtaining asymptotic estimates for the exponentially small splitting of separatrices to whiskered tori with quadratic frequencies
Delshams Valdés, Amadeu; Gonchenko, Marina; Gutiérrez Serrés, Pere (2014-07)
Report de recerca
Accés obert -
A pseudo-normal form for planar vector fields
Delshams Valdés, Amadeu; Guillamon Grabolosa, Antoni; Lázaro Ochoa, José Tomás (2001)
Article
Accés obert -
Abundance of attracting, repelling and elliptic periodic orbits in two-dimensional reversible maps
Delshams Valdés, Amadeu; Gonchenko, S.V.; Lázaro Ochoa, José Tomás; Stenkin, Oleg (2013-01-01)
Article
Accés obertWe study dynamics and bifurcations of two-dimensional reversible maps having non-transversal heteroclinic cycles containing symmetric saddle fixed points. We consider one-parameter families of reversible maps unfolding ... -
Abundance of attracting, repelling and elliptic periodic orbits in two-dimensional reversible maps
Delshams Valdés, Amadeu; Lázaro Ochoa, José Tomás; Gonchenko, S.V.; Sten'kin, Oleg (2012-01-12)
Report de recerca
Accés obertAbstract. We 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 reversible ... -
An invitation to singular symplectic geometry
Miranda Galcerán, Eva; Delshams Valdés, Amadeu; Dempsey Bradell, Roisin Mary; Oms, Cedric; Planas Bahí, Arnau (2019)
Article
Accés obertIn this paper we analyze in detail a collection of motivating examples to consider bm-symplectic forms and folded-type symplectic structures. In particular, we provide models in Celestial Mechanics for every bm-symplectic ... -
An invitation to singular symplectic geometry
Miranda Galcerán, Eva; Delshams Valdés, Amadeu; Planas Bahí, Arnau; Oms, Cedric; Dempsey Bradell, Roisin Mary (2017)
Report de recerca
Accés obertIn this paper we analyze in detail a collection of motivating examples to consider bm- symplectic forms and folded-type symplectic structures. In particular, we provide models in Celestial Mechanics for every bm-symplectic ... -
Arnold diffusion for a complete family of perturbations
Delshams Valdés, Amadeu; Gonçalves Schaefer, Rodrigo (Springer, 2017-01-01)
Article
Accés obertIn this work we illustrate the Arnold diffusion in a concrete example — the a priori unstable Hamiltonian system of 2 + 1/2 degrees of freedom H(p, q, I, f, s) = p2/2+ cos q - 1 + I2/2 + h(q, f, s; e) — proving that for ... -
Arnold diffusion for a complete family of perturbations with two independent harmonics
Delshams Valdés, Amadeu; Gonçalves Schaefer, Rodrigo (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 ... -
Arnold's mechanism of diffusion in the spatial circular restricted three-body problem: A semi-analytical argument
Delshams Valdés, Amadeu; Gidea, Marian; Roldán, Pablo (2016-11-01)
Article
Accés obertWe consider the spatial circular restricted three-body problem, on the motion of an infinitesimal body under the gravity of Sun and Earth. This can be described by a 3-degree of freedom Hamiltonian system. We fix an energy ... -
Bi-asymptotic billiard orbits inside perturbed ellipsoids
Bolotin, S.; Delshams Valdés, Amadeu; Fedorov, Yuri; Ramírez Ros, Rafael (2001)
Article
Accés obert -
Consideracions al voltant de la Funció Beta a l’obra de Leonhard Euler (1707-1783)
Delshams Valdés, Amadeu; Massa Esteve, Maria Rosa (Centre de recerca per a la Història de la Tècnica "Francesc Santponç i Roca". Escola Tècnica Superior d'Enginyeria Industrial de Barcelona (Universitat Politècnica de Catalunya). Càtedra UNESCO de Tècnica i Cultura de la UPC, 2008)
Article
Accés obert -
Continuation of the exponentially small lower bounds for the splitting of separatrices to a whiskered torus with silver ratio
Delshams Valdés, Amadeu; Gonchenko, Marina; Gutiérrez Serrés, Pere (2014-09)
Report de recerca
Accés obertWe study the exponentially small splitting of invariant manifolds of whiskered (hyperbolic) tori with two fast frequencies in nearly-integrable Hamiltonian systems whose hyperbolic part is given by a pendulum. We consider ... -
Continuation of the exponentially small transversality for the splitting of separatrices to a whiskered torus with silver ratio
Delshams Valdés, Amadeu; Gonchenko, Marina; Gutiérrez Serrés, Pere (Springer, 2014-11)
Article
Accés obertWe study the exponentially small splitting of invariant manifolds of whiskered (hyperbolic) tori with two fast frequencies in nearly integrable Hamiltonian systems whose hyperbolic part is given by a pendulum. We ... -
Effective stability and KAM theory
Delshams Valdés, Amadeu; Gutiérrez Serrés, Pere (1995)
Article
Accés obertThe two main stability results for nearly integrable Hamiltonian systems are revisited: Nekhoroshev theorem, concerning exponential lower bounds for the stability time (effective stability), and KAM theorem, concerning ... -
Effective stability in reversible systems
Delshams Valdés, Amadeu; Lázaro Ochoa, José Tomás (1997)
Article
Accés obertIn this paper we present a procedure to put in normal form a nearly-integrable reversible system, not necessarily a Hamiltonian system. Furthermore, non-resonant stability estimates are obtained. As an application we discuss ...