Exploració per tema "Global analysis (Mathematics)"
Ara es mostren els items 1-20 de 33
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Bifurcation at complex instability
(1995)
Article
Accés obertIn an autonomous Hamiltonian system with three or more degrees of freedom, a family of periodic orbits may become unstable when two pairs of characteristic multipliers coallesce on the unit circle at points not equal to ... -
Càlcul de corrents crítics en materials superconductors via SSA i inversió de Fourier
(Universitat Politècnica de Catalunya, 2017-07)
Treball Final de Grau
Accés obertDonada una mesura del component vertical Bz del camp magnètic que genera un corrent bidimensional, resolem el problema de Biot-Savart invers per tal de calcular el corrent J al llarg de la mostra. Per tal de fer el càlcul ... -
Central configurations on the charged three-body problem
(1996)
Capítol de llibre
Accés obert -
Centre and isochronicity conditions for systems with homogeneous nonlinearities
(1995)
Article
Accés obertWe study the centre-focus problem for systems with homogeneous nonlinearities. In the centre case we study the characterization of the isochronous centres. More explicitly, we derive six necessary conditions to be a ... -
Characterisation of the electrical disturbances manifested in the RR series of the selective acute occlusion of atrial branches during angioplasty
(Universitat Politècnica de Catalunya, 2012)
Projecte/Treball Final de Carrera
Accés restringit per decisió de l'autorIschaemic cardiomyopathy is a common disease which may lead to sudden cardiac death (SCD). By the help of angioplasty, a stent can prevent an ischemia by blood vessel extension. The purpose of this study is to predict ... -
Constant sigma_2-curvature metrics with non isolated singularities
(Universitat Politècnica de Catalunya, 2016-10)
Projecte Final de Màster Oficial
Accés restringit per decisió de l'autorThe aim of this thesis is to give a method to produce families of complete Riemannian metrics with positive constant $\sigma_k$-curvature equal to $2^{-k}\binom{n}{k}$ on $M\setminus \Lambda^p$, where $M$ is a Riemannian ... -
Dimension of the orbit of marked subspaces
(2004)
Article
Accés obertGiven a nilpotent endomorphism, we consider the manifold of invariant subspaces having a fixed Segre characteristic. In [Linear Algebra Appl., 332–334 (2001) 569], the implicit form of a miniversal deformation of an ... -
Effective reducibility of quasiperiodic linear equations close to constant coefficients
(1995)
Article
Accés obertLet us consider the differential equation $$ \dot{x}=(A+\varepsilon Q(t,\varepsilon))x, \;\;\;\; |\varepsilon|\le\varepsilon_0, $$ where $A$ is an elliptic constant matrix and $Q$ depends on time in a quasiperiodic ... -
Effective stability and KAM theory
(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 ... -
Estimates on invariant tori near an elliptic equilibrium point of a Hamiltonian system
(1996)
Article
Accés obertWe give a precise statement for KAM theorem in a neighbourhood of an elliptic equilibrium point of a Hamiltonian system. If the frequencies of the elliptic point are nonresonant up to a certain order $K\ge4$, and a ... -
Exponentially small splitting of separatrices for perturbed integrable standard-like maps
(1997)
Article
Accés obertWe consider fast quasiperiodic perturbations with two frequencies $(1/\varepsilon,\gamma/\varepsilon)$ of a pendulum, where $\gamma$ is the golden mean number. The complete system has a two-dimensional invariant ... -
Exponentially small splitting of separatrices under fast quasiperiodic forcing
(1997)
Article
Accés obertWe consider fast quasiperiodic perturbations with two frequencies $(1/\varepsilon,\gamma/\varepsilon)$ of a pendulum, where $\gamma$ is the golden mean number. The complete system has a two-dimensional invariant ... -
Lower and upper bounds for the splitting of separatrices of the pendulum under a fast quasiperiodic forcing
(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
(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 ... -
Miniversal deformations of marked matrices
(2001)
Article
Accés obertGiven the set of square matricesM⊂Mn+m(C) that keep the subspace W = Cnx{0} ⊂ Cn+m invariant, we obtain the implicit form of a miniversal deformation of a matrix a∈M, and we compute it explicitely when this matrix is ... -
Motion near the transition to complex instability: some examples
(1997)
Article
Accés obertComplex instability is a generic kind of instability in Hamiltonian systems with three degrees of freedom. In this work, some examples of such instability are shown, together with a numerical analysis of the dynamics ... -
Normal-internal resonances in quasi-periodically forced oscillators: a conservative approach
(2003)
Article
Accés obertWe perform a bifurcation analysis of normal–internal resonances in parametrised families of quasi–periodically forced Hamiltonian oscillators, for small forcing. The unforced system is a one degree of freedom oscillator, ... -
Numerical computation of normal forms around some periodic orbits of the restricted three body problem
(1997)
Article
Accés obertIn this paper we introduce a general methodology for computing (numerically) the normal form around a periodic orbit of an autonomous analytic Hamiltonian system. The process follows two steps. First, we expand the ... -
On quasiperiodic perturbations of elliptic equilibrium points
(1995)
Article
Accés obertThis work focusses on quasiperiodic time-dependent perturbations of ordinary differential equations near elliptic equilibrium points. This means studying $$ \dot{x}=(A+\varepsilon Q(t,\varepsilon))x+\varepsilon ... -
On the normal behaviour of partially elliptic lower dimensional tori of hamiltonian systems
(1996)
Article
Accés obertThe purpose of this paper is to study the dynamics near a reducible lower dimensional invariant tori of a finite-dimensional autonomous Hamiltonian system with $\ell$ degrees of freedom. We will focus in the case in ...
