Now showing items 1-20 of 99

    • 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
    • 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 pseudo-normal form for planar vector fields 

      Delshams Valdés, Amadeu; Guillamon Grabolosa, Antoni; Lázaro Ochoa, José Tomás (2001)
      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 ...
    • 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 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 ...
    • 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 ...
    • Canard-induced complex oscillations in an excitatory network 

      Desroches, Mathieu; Guillamon Grabolosa, Antoni; Rinzel, John; Köksal Ersöz, Elif; Tabak, Joël (2020-01-01)
      Article
      Open Access
      In Neuroscience, mathematical modelling involving multiple spatial and temporal scales can unveil complex oscillatory activity such as excitable responses to an input current, subthreshold oscillations, spiking or bursting. ...
    • 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
      Open Access
      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 ...