Ara es mostren els items 18-33 de 33

    • Limit cycles bifurcating from a degenerate center 

      Llibre Saló, Jaume; Pantazi, Chara (2016-02-01)
      Article
      Accés obert
      We study the maximum number of limit cycles that can bifurcate from a degenerate center of a cubic homogeneous polynomial differential system. Using the averaging method of second order and perturbing inside the class of ...
    • Morphisms and inverse problems 

      Christopher, Colin; Llibre Saló, Jaume; Pantazi, Chara; Walcher, Sebastian (2011-11-03)
      Report de recerca
      Accés obert
      In order to investigate polynomial vector ¯elds admitting a prescribed Darboux integrating factor, we show that it is helpful to employ morphisms of the a±ne plane. In particular, such morphisms may be used to remove ...
    • Morphisms and inverse problems for Darboux integrating factors 

      Llibre Saló, Jaume; Pantazi, Chara; Walcher, Sebastian (2013-12)
      Article
      Accés obert
      Polynomial vector fields which admit a prescribed Darboux integrat- ing factor are quite well-understood when the geometry of the underlying curve is nondegenerate. In the general setting morphisms of the affine plane ...
    • On planar polynomial vector fields with elementary first integrals 

      Christopher, Colin; Pantazi, Chara; Llibre Saló, Jaume; Walcher, Sebastian (2019-10-05)
      Article
      Accés obert
      We show that under rather general conditions a polynomial differential system having an elementary first integral already must admit a Darboux first integral, and we explicitly characterize the vector fields in this class. ...
    • On the 16th Hilbert problem for algebraic limit cycles 

      Llibre Saló, Jaume; Ramírez Inostroza, Rafael Orlando; Sadovskaia Nurimanova, Natalia Guennadievna (2010-03-15)
      Article
      Accés restringit per política de l'editorial
      For a polynomial planar vector field of degree n ≥ 2 with generic invariant algebraic curves we show that the maximum number of algebraic limit cycles is 1 + (n − 1)(n − 2)/2 when n is even, and (n − 1)(n − 2)/2 when n is ...
    • On the 16th Hilbert problem for limit cycles on nonsingular algebraic curves 

      Llibre Saló, Jaume; Ramírez Inostroza, Rafael Orlando; Sadovskaia Nurimanova, Natalia Guennadievna (2011-01-15)
      Article
      Accés restringit per política de l'editorial
      We give an upper bound for the maximum number N of algebraic limit cycles that a planar polynomial vector field of degree n can exhibit if the vector field has exactly k nonsingular irreducible invariant algebraic curves. ...
    • On the central configurations of the planar 1 + 3 body problem 

      Corbera, M.; Cors Iglesias, Josep Maria; Llibre Saló, Jaume (2011)
      Article
      Accés obert
      We consider the Newtonian 4 body problem in the plane with a dominat mass M. We study the planar central configurations of this problem when the remaining masses are infinitesimal. We obtain two diferent classes of central ...
    • Periodic orbits of horseshoe type in the planar restricted three-body problem 

      Llibre Saló, Jaume; Ollé Torner, Mercè (2002)
      Article
      Accés obert
    • Polynomial differential systems having a given Darbouxian first integral 

      Llibre Saló, Jaume; Pantazi, Chara (Elsevier, 2004)
      Article
      Accés obert
      The Darbouxian theory of integrability allows to determine when a polynomial differential system in C2 has a first integral of the kind f λ1 1 ···f λp p exp(g/h) where fi , g and h are polynomials in C[x, y], and λi ∈ C ...
    • Quadratic planar differential systems with algebraic limit cycles via quadratic plane Cremona maps 

      Alberich Carramiñana, Maria; Ferragut Amengual, Antoni Manel; Llibre Saló, Jaume (Elsevier, 2021)
      Article
      Accés obert
      In this paper we study the action of planar birational transformations, also known as plane Cremona maps, on quadratic planar differential systems. We provide geometrical characterizations of when a quadratic system is ...
    • Qualitative study of a model with Rastall gravity 

      Pantazi, Chara; Llibre Saló, Jaume (2020-12-17)
      Article
      Accés obert
      We consider the Rastall theory for the flat Friedmann-Robertson-Walker Universe filled with a perfect fluid that satisfies a linear equation of state. The corresponding dynamical system is a two dimensional system of ...
    • Qualitative study of the Selkov model 

      Llibre Saló, Jaume; Pantazi, Chara (Elsevier, 2024-06-05)
      Article
      Accés obert
      The Selkov oscillator was formulated in 1968 and now it is a classical model for studying the glycolysis. It is a differential system of two equations depending on two parameters in dimensionless variables. When the two ...
    • Some inverse problems 

      Christopher, Colin; Llibre Saló, Jaume; Pantazi, Chara; Walcher, Sebastian (2011-07-06)
      Report de recerca
      Accés restringit per política de l'editorial
      The Darboux theory of integrability for planar polynomial di®erential equations is a classical ¯eld, with connections to Lie symmetries, di®erential algebra and other areas of mathematics. In the present paper we introduce ...
    • The motion of Saturn coorbital satellites in the restricted three-body problem 

      Llibre Saló, Jaume; Ollé Torner, Mercè (2001)
      Article
      Accés obert
      This paper provides a description of the motion of Saturn coorbital satellites Janus and Epimetheus by means of horseshoe periodic orbits in the framework of the planar restricted three-body problem for the mass parameter ...
    • Three-dimensional Lotka–Volterra systems with 3:-1:2-resonance 

      Aziz, Waleed; Christopher, Colin; Llibre Saló, Jaume; Pantazi, Chara (2021-08)
      Article
      Accés obert
      We study the local integrability at the origin of a nine-parameter family of three-dimensional Lotka–Volterra differential systems with (3:- 1:2)-resonance. We give necessary and sufficient conditions on the parameters of ...
    • Trapezoid central configurations 

      Corbera, Montserrat; Cors Iglesias, Josep Maria; Llibre Saló, Jaume; Perez Chavela, Ernesto (2019-04-01)
      Article
      Accés obert
      We classify all planar four–body central configurations where two pairs of the bodies are on parallel lines. Using cartesian coordinates, we show that the set of four–body trapezoid central configurations with positive ...