Now showing items 1-20 of 162

  • A chaotic secure communication scheme based on duffing oscillators and frequency estimation 

    Zapateiro, Mauricio; Vidal Seguí, Yolanda; Acho Zuppa, Leonardo (2013)
    Conference report
    Open Access
    This work presents a new technique to securely transmit and retrieve a message signal via chaotic systems. In our system, a two-valued message signal modulates the frequency of a Duffing oscillator sinusoidal term. An ...
  • A characterization of isochronous centres in terms of symmetries 

    Freire, Emilio; Gasull Embid, Armengol; Guillamon Grabolosa, Antoni (2000)
    Article
    Open Access
    We present a description of isochronous centres of planar vector fields $X$ by means of their groups of symmetries. More precisely, given a normalizer $U$ of $X$ (i.e., $[X,U]=\mu X$, where $\mu$ is a scalar function), we ...
  • A contribution to video coding using layers 

    Torres Urgell, Lluís; Lecha, M (1998)
    Conference report
    Open Access
    Layered representations of video sequences, originally introduced in [1], are important in several applications. Specifically, they are very appropriate for object tracking, object manipulation, content-based scalability ...
  • Action-angle variables and a KAM theorem for b-Poisson manifolds 

    Miranda Galcerán, Eva; Kiesenhofer, Anna; Scott, Geoffrey (2016-01-01)
    Article
    Open Access
    In this article we prove an action-angle theorem for b-integrable systems on b-Poisson manifolds improving the action-angle theorem contained in [14] for general Poisson manifolds in this setting. As an application, we ...
  • Adaptive backstepping control of a class of hysteretic systems 

    Ikhouane, Fayçal; Mañosa Fernández, Víctor; Rodellar Benedé, José (SPIE Press. The International Society for Optical Engineering, 2003-08-01)
    Part of book or chapter of book
    Open Access
    A backstepping-based adaptive control is designed for a class of one degree of freedom hysteretic system. The true hysteretic behavior does not need to be known for the controller design. A polynomial description is assumed ...
  • Adiabatic invariant of the harmonic oscillator, complex matching and resurgence 

    Bonet Revés, Carles; Sauzin, D.; Martínez-Seara Alonso, M. Teresa; València Guitart, Marta (1997)
    Article
    Open Access
    The linear oscillator equation with a frequency depending slowly on time is used to test a method to compute exponentially small quantities. This work present the matching method in the complex plane as a tool to obtain ...
  • A discrete bernoulli free boundary problem 

    González Nogueras, María del Mar; Gualdani, Maria; Shagholian, Henrick (2012-04)
    External research report
    Open Access
    We consider a free boundary problem for the p-Laplace operator which is related to the so-called Bernoulli free boundary problem. In this formulation, the classical boundary gradient condition is replaced by a condition ...
  • A Hamiltonian study of the stability and bifurcations for the satellite problem 

    Muñoz Lecanda, Miguel Carlos; Rodríguez Olmos, Miguel Andrés; Teixidó Román, Miguel (2015-10-01)
    Article
    Open Access
    We study the dynamics of a rigid body in a central gravitational field modeled as a Hamiltonian system with continuous rotational symmetries following the geometric framework of Wang et al. Novelties of our work are the ...
  • A logistic queue model for network traffic modeling and simulation 

    Coltraro Ianniello, Franco (Universitat Politècnica de Catalunya, 2017-07)
    Master thesis
    Open Access
    In this work we present a continuous queuing model called the logistic queue model. We show that in terms of queue size and outflow prediction, our model is as precise as a discrete event simulator with the additional ...
  • An analytic-numerical method of computation of the Liapunov and period constants derived from their algebraic structure 

    Gasull Embid, Armengol; Guillamon Grabolosa, Antoni; Mañosa Fernández, Víctor (1996)
    Article
    Open Access
    We consider the problem of computing the Liapunov and the period constants for a smooth differential equation with a non degenerate critical point. First, we investigate the structure of both constants when they are ...
  • An efficient iterative method for computing deflections of Bernoulli–Euler–von Karman beams on a nonlinear elastic foundation 

    Ahmad, Fayyaz; Jang, Taek Soo; Carrasco, Juan A.; Shafiq Ur, Rehman; Ali, Zulfiqar; Ali, Nukhaze (2018-10-01)
    Article
    Restricted access - publisher's policy
    An efficient iterative method is developed for the static analysis of large deflections of an infinite beam with variable cross-section resting on a nonlinear foundation. A pseudo spring constant is added and explicit ...
  • A new algorithm for finding rational first integrals of polynomial vector fields 

    Ferragut Amengual, Antoni Manel; Giacomini, Héctor (2009-05)
    External research report
    Open Access
    We present a new method to compute rational first integrals of a planar polynomial vector field. The algorithm is in general much faster than the usual methods and also allows to compute the remarkable curves associated ...
  • A new subdivision algorithm for the flow propagation using polynomial algebras 

    Pérez Palau, Daniel; Gómez Muntané, Gerard; Masdemont Soler, Josep (2018-08-01)
    Article
    Restricted access - publisher's policy
    The Jet Transport method has emerged as a powerful tool for the numerical integration of ordinary differential equations; it uses polynomial expansions to approximate the flow map associated to the differential equation ...
  • An explicit expression of the first Liapunov and period constants with applications 

    Gasull Embid, Armengol; Guillamon Grabolosa, Antoni; Mañosa Fernández, Víctor (1996)
    Article
    Open Access
    In this paper, we study systems in the plane having a critical point with pure imaginary eigenvalues, and we search for effective conditions to discern whether this critical point is a focus or a center; in the case of it ...
  • A note on the symplectic topology of b-manifolds 

    Miranda Galcerán, Eva; Martinez Torres, David; Frejlich, Pedro (2017)
    Article
    Open Access
    Poisson manifold (M2n; ) is b-symplectic if Vn is transverse to the zero section. In this paper we apply techniques native to Symplectic Topology to address questions pertaining to b-symplectic manifolds. We pro- vide ...
  • Aproximación del problema de Stokes mediante elementos finitos mixtos de tipo cross-grid 

    Blasco Lorente, Jorge; Armentano, María G. (2009)
    Conference lecture
    Restricted access - publisher's policy
    En esta comunicación introducimos una familia de métodos de elementos finitos mixtos para la resolución numérica del problema de Stokes en dimensión 2. En estos métodos, la presión se interpola en una malla de elementos ...
  • A pseudo-normal form for planar vector fields 

    Delshams Valdés, Amadeu; Guillamon Grabolosa, Antoni; Lázaro Ochoa, José Tomás (2001)
    Article
    Open Access
  • A singular initial value problem to construct density-equalizing maps 

    Avinyó Andrés, Albert; Solà-Morales Rubió, Joan de; València Guitart, Marta (2011-12)
    Article
    Restricted access - publisher's policy
    The diffusion-based algorithm to produce density-equalizing maps interprets diffusion as an advection process. This algorithm uses the dynamics of a flow that is defined by an initial value problem that turns out to be ...
  • A singular initial value problem to construct density-equalizing maps 

    Avinyó Andrés, Albert; Solà-Morales Rubió, Joan de; València Guitart, Marta (2011-05)
    External research report
    Open Access
    The diffusion-based algorithm to produce density-equalizing maps interprets diffusion as an advection process. This algorithm uses the dynamics of a flow that is defined by an initial value problem that turns out to be ...
  • A smooth center manifold theorem which applies to some III-posed partial differential equations with unbounded nonlinearities 

    Llave Canosa, Rafael de la (2009)
    Article
    Restricted access - publisher's policy
    We prove the existence of a smooth center manifold for several partial differential equations, including ill posed equations with unbounded nonlinearities. We also prove smooth dependence on parameters with respect to ...