Now showing items 1-20 of 96

  • 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 computational and geometric approach to phase resetting curves and surfaces 

    Guillamon Grabolosa, Antoni; Huguet Casades, Gemma (2009)
    Article
    Open Access
  • 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 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 ...
  • 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 ...
  • 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 pseudo-normal form for planar vector fields 

    Delshams Valdés, Amadeu; Guillamon Grabolosa, Antoni; Lázaro Ochoa, José Tomás (2001)
    Article
    Open Access
  • Bifurcation at complex instability 

    Ollé Torner, Mercè; Pfenniger, Daniel (1995)
    Article
    Open Access
    In 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 ...
  • Boundary value problems for Schrödinger operators on a Path Associated to Orthogonal Polynomials 

    Carmona Mejías, Ángeles; Encinas Bachiller, Andrés Marcos; Gago Álvarez, Silvia (Springer, 2013)
    Part of book or chapter of book
    Restricted access - publisher's policy
    In this work, we concentrate on determining explicit expressions, via suitable orthogonal polynomials on the line, for the Green function associated with any regular boundary value problem on a weighted path, whose weights ...
  • Bounded and dissipative solutions of the Bouc-Wen model for hysteretic structural systems 

    Ikhouane, Fayçal; Mañosa Fernández, Víctor; Rodellar Benedé, José (2004-06)
    Part of book or chapter of book
    Open Access
    The aim of this paper is to give the conditions on the hysteretic Bouc-Wen model so that (i) it has the property of being bounded input bounded output (BIBO), and (ii) it dissipates energy (or is passive). This study leads ...
  • Breakdown of heteroclinic orbits for analytic unfoldings of the hopf-zero singularity. The singular case 

    Baldomá Barraca, Inmaculada; Castejón i Company, Oriol; Martínez-Seara Alonso, M. Teresa (2011)
    External research report
    Open Access
    In this paper we prove the breakdown of an heteroclinic connection in the analytic versal unfoldings of the generic Hopf-Zero singularity. This heteroclinic orbit appears at any order if one performs the normal form around ...
  • Centers and uniform isochronous centers of planar polynomial differential systems 

    Llibre Saló, Jaume; Ramirez Inostroza, Rafael; Ramírez Sadovski, Valentín; Sadovskaia Nurimanova, Natalia Guennadievna (2018-09)
    Article
    Restricted access - publisher's policy
    For planar polynomial vector fields of the form (-y+X(x,y))¿¿x+(x+Y(x,y))¿¿y, where X and Y start at least with terms of second order in the variables x and y, we determine necessary and sufficient conditions under which ...
  • Centre and isochronicity conditions for systems with homogeneous nonlinearities 

    Gasull Embid, Armengol; Guillamon Grabolosa, Antoni; Mañosa Fernández, Víctor (1995)
    Article
    Open Access
    We 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 ...
  • Condiciones de contorno en modelos de gradiente con desplazamientos suavizados 

    Tamayo Mas, Elena; Rodríguez Ferran, Antonio (2012)
    Article
    Open Access
    Los modelos de gradiente basados en desplazamientos suavizados son una alternativa a los modelos est´andares para simular num´ericamente el proceso de fallo de materiales. En esta formulaci´on alternativa coexisten los ...
  • Constraint algorithm for extremals in optimal control problems 

    Barbero Liñán, María; Muñoz Lecanda, Miguel Carlos (2007-07-27)
    Article
    Open Access
    A characterization of different kinds of extremals of optimal control problems is given if we take an open control set. A well known constraint algorithm for implicit differential equations is adapted to the study of ...
  • Continua of periodic points for planar integrable rational maps 

    Gasull Embid, Armengol; Llorens, Mireia; Mañosa Fernández, Víctor (Research India Publications, 2016-09)
    Article
    Open Access
    We present three alternative methodologies to find continua of periodic points with a prescribed period for rational maps having rational first integrals. The first two have been already used by other authors and apply ...
  • Continua of periodic points for planar integrable rational maps. 

    Gasull Embid, Armengol; Llorens, Mireia; Mañosa Fernández, Víctor (2015-11-30)
    External research report
    Open Access
    We present three alternative methodologies to find continua of periodic points with a prescribed period for rational maps having rational first integrals. The first two have been already used for other authors and apply ...