Now showing items 1-20 of 170

    • 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 ...
    • 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 ...
    • 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
      Open Access
      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 ...
    • 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 ...
    • 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 (2011-05)
      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 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 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 ...
    • A survey of the hysteretic Duhem model 

      Ikhouane, Fayçal (2018-11-01)
      Article
      Open Access
      The Duhem model is a simulacrum of a com- plex and hazy reality: hysteresis. Introduced by Pierre Duhem to provide a mathematical representation of thermodynamical irreversibility, it is used to ...
    • 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 ...
    • 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 ...
    • 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 ...