Ara es mostren els items 1-20 de 27

  • A characterization of isochronous centres in terms of symmetries 

    Freire, Emilio; Gasull Embid, Armengol; Guillamon Grabolosa, Antoni (2000)
    Article
    Accés obert
    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
    Accés obert
  • A drone based system for surveillance applications in coastal zone 

    Cantero, Adrián; Gallego, David; López, Pedro; Molina, Rafael; Sánchez, Gonzalo; Sueldo, Agustín; Guerrero, Antonio; Guillamon Grabolosa, Antoni (SARTI, 2015)
    Article
    Accés obert
    This paper introduces an unmanned aircraft vehicle (multicopter) for coastal applications. This vehicle has surveillance purposes, and it is configured with routes in such a way that the vehicle is capable of displaying ...
  • A pseudo-normal form for planar vector fields 

    Delshams Valdés, Amadeu; Guillamon Grabolosa, Antoni; Lázaro Ochoa, José Tomás (2001)
    Article
    Accés obert
  • aCTeX: Autoaprenentatge científico-tècnic en xarxa 

    Guillamon Grabolosa, Antoni; Ferrer, Albert (Universitat Politècnica de Catalunya. Institut de Ciències de l'Educació, 2007-06-28)
    Text en actes de congrés
    Accés obert
    aCTeX és una aplicació web que genera dinàmicament llistats de preguntes tipus test, amb la particularitat que admet expressions matemàtiques introduïdes en llenguatge LaTeX a la base de dades. L’aplicació executa la ...
  • 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
    Accés obert
    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
    Accés obert
    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 ...
  • Bifurcations analysis of oscillating hypercycles 

    Guillamon Grabolosa, Antoni; Fontich, Ernest; Sardañés, Josep (2015-12-21)
    Article
    Accés obert
    We investigate the dynamics and transitions to extinction of hypercycles governed by periodic orbits. For a large enough number of hypercycle species (n > 4) the existence of a stable periodic orbit has been previously ...
  • Centre and isochronicity conditions for systems with homogeneous nonlinearities 

    Gasull Embid, Armengol; Guillamon Grabolosa, Antoni; Mañosa Fernández, Víctor (1995)
    Article
    Accés obert
    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 ...
  • Dissecting estimation of conductances in subthreshold regimes 

    Vich, Catalina; Guillamon Grabolosa, Antoni (2015-12-01)
    Article
    Accés obert
    We study the influence of subthreshold activity in the estimation of synaptic conductances. It is known that differences between actual conductances and the estimated ones using linear regression methods can be huge in ...
  • Estimation of synaptic conductance in the spiking regime for the McKean neuron model 

    Guillamon Grabolosa, Antoni; Prohens Sastre, Rafel; Teruel Aguilar, Antonio E.; Vich Llompart, Catalina (2017-01-01)
    Article
    Accés obert
    In this work, we aim at giving a first proof of concept to address the estimation of synaptic conductances when a neuron is spiking, a complex inverse nonlinear problem which is an open challenge in neuroscience. Our ...
  • Estimation of synaptic conductances in presence of nonlinear effects caused by subthreshold ionic currents 

    Vich Llompart, Catalina; Guillamon Grabolosa, Antoni; Ditlevsen, Susanne; Berg, Rune W. (2017-07)
    Article
    Accés obert
    Subthreshold fluctuations in neuronal membrane potential traces contain nonlinear components, and employing nonlinear models might improve the statistical inference. We propose a new strategy to estimate synaptic conductances, ...
  • Estimation of the synaptic conductance in a McKean-model neuron 

    Guillamon Grabolosa, Antoni; Prohens Sastre, Rafel; Teruel Aguilar, Antonio E.; Vich Llompart, Catalina (2015)
    Comunicació de congrés
    Accés obert
    Estimating the synaptic conductances impinging on a single neuron directly from its membrane potential is one of the open problems to be solved in order to understand the flow of information in the brain. Despite the ...
  • First derivative of the period function with applications 

    Freire, Emilio; Gasull Embid, Armengol; Guillamon Grabolosa, Antoni (2001)
    Article
    Accés obert
    Given a centre of a planar differential system, we extend the use of the Lie bracket to the determination of the monotonicity character of the period function. As far as we know, there are no general methods to study ...
  • Full analysis of small hypercycles with shortcircuits in prebiotic evolution 

    Lázaro Ochoa, José Tomás; Guillamon Grabolosa, Antoni; Fontich, Ernest; Sardañés, Josep (2017-01-05)
    Article
    Accés restringit per política de l'editorial
    It is known that hypercycles are sensitive to the so-called parasites and short-circuits. While the impact of parasites has been widely investigated for well-mixed and spatial hypercycles, the effect of short-circuits in ...
  • Geometric tools to determine the hyperbolicity of limit cycles 

    Guillamon Grabolosa, Antoni; Sabatini, Marco (2005)
    Article
    Accés obert
    In this paper we present a new method to study limit cycles’ hyperbolicity. The main tool is the function ? = ([V,W] ^ V )/(V ^W), where V is the vector field under investigation and W a transversal one. Our approach ...
  • Limit cycles and Lie symmetries 

    Freire, Emilio; Gasull Embid, Armengol; Guillamon Grabolosa, Antoni (2005)
    Article
    Accés obert
    Given a planar vector field U which generates the Lie symmetry of some other vector field X, we prove a new criterion to control the stability of the periodic orbits of U. The problem is linked to a classical problem ...
  • Limit cycles for generalized Abel equations 

    Gasull Embid, Armengol; Guillamon Grabolosa, Antoni (2005)
    Article
    Accés obert
    This paper deals with the problem of finding upper bounds on the number of periodic solutions of a class of one-dimensional non-autonomous differential equations: those with the right-hand sides being polynomials of ...
  • Multi-stable perception balances stability and sensitivity 

    Pastukhov, Alexander; Garcia Rodriguez, Pedro E.; Haenicke, Joachim; Guillamon Grabolosa, Antoni; Deco, Gustavo; Braun, Jochen (2013)
    Article
    Accés obert
    We report that multi-stable perception operates in a consistent, dynamical regime, balancing the conflicting goals of stability and sensitivity. When a multi-stable visual display is viewed continuously, its phenomenal ...
  • Period function for perturbed isochronous centres 

    Freire, Emilio; Gasull Embid, Armengol; Guillamon Grabolosa, Antoni (2001)
    Article
    Accés obert