Browsing Articles publicats (Matemàtica) by Title

Now showing items 235-244 of 244

    • Universal centers and composition conditions 

      Giné, Jaume; Grau Montaña, Maite; Llibre, Jaume (London Mathematical Society, 2013)
      In this paper, we characterize the universal centres of the ordinary differential equations , where ai(θ) are trigonometric polynomials, in terms of the composition conditions. These centres are closely related with the ...

    • Universal centers in the cubic trigonometric Abel equation 

      Giné, Jaume; Grau Montaña, Maite; Santallusia Esvert, Xavier (Bolyai Institute. University of SzegedHungarian Academy of Sciences, 2014)
      We study the center problem for the trigonometric Abel equation dρ/dθ=a1(θ)ρ2+a2(θ)ρ3,dρ/dθ=a1(θ)ρ2+a2(θ)ρ3, where a1(θ)a1(θ) and a2(θ)a2(θ) are cubic trigonometric polynomials in θθ. This problem is closely connected with ...

    • Vertex‐transitive graphs that remain connected after failure of a vertex and its neighbors 

      Hamidoune, Yahya Ould; Lladó, A.; López Masip, Susana-Clara (Wiley, 2011)
      A d-regular graph is said to be superconnected if any disconnecting subset with cardinality at most d is formed by the neighbors of some vertex. A superconnected graph that remains connected after the failure of a vertex ...

    • Volcanoes of l-isogenies of elliptic curves over finite fields: the case l=3 

      Miret, Josep M. (Josep Maria); Sadornil Renedo, Daniel; Tena Ayuso, Juan; Tomàs Cuñat, Rosa Ana; Valls Marsal, Magda (Universitat Autònoma de Barcelona. Departament de Matemàtiques, 2007)
      This paper is devoted to the study of the volcanoes of l-isogenies of elliptic curves over a finite field, focusing on their height as well as on the location of curves across its different levels. The core of the paper ...

    • Voltammetric currents for any ligand-to-metal concentration ratio in fully labile metal-macromolecular complexation. Easy computations, analytical properties of the currents and graphical method to estimate the stability constant 

      Galceran i Nogués, Josep; Cecilia Averós, Joan; Salvador, José; Monné Esquerda, Josep; Torrent, Marià; Companys Ferran, Encarnació; Puy Llorens, Jaume; Garcés, Josep Lluís; Mas i Pujadas, Francesc (Elsevier, 1999)
      In order to enable a wider use of voltammetric methods in speciation analysis, it is convenient not to be restricted by ligand excess conditions. This work assumes labile ideal complexation of a metal ion by a ligand, ...

    • Voltammetric lability of metal complexes at spherical micorelectrodes with various radii 

      Galceran i Nogués, Josep; Puy Llorens, Jaume; Salvador, José; Cecilia Averós, Joan; Leeuwen, Herman P. van (Elsevier, 2001)
      The size of a microelectrode can have a dramatic impact on the relative importance of the diffusional and kinetic contributions to the voltammetric current of an electroactive metal ion in a complexing medium. Decreasing ...

    • Voltammetric lability of multiligand complexes: the case of ML2 

      Puy Llorens, Jaume; Cecilia Averós, Joan; Galceran i Nogués, Josep; Town, Raewyn M.; Leeuwen, Herman P. van (Elsevier, 2004)
      The voltammetric lability of a complex system, where a metal ion M and a ligand L form the species ML and ML2, is examined. Together with the rigorous numerical simulation of the problem, two limiting cases are analysed ...

    • Weierstrass integrability in Liénard differential systems 

      Giné, Jaume; Llibre, Jaume (Elsevier, 2011)
      In this work we study the Liénard differential systems that admit a Weierstrass first integral or a Weierstrass inverse integrating factor

    • Weierstrass integrability of differential equations 

      Giné, Jaume; Grau Montaña, Maite (Elsevier, 2010)
      The integrability problem consists in finding the class of functions a first integral of a given planar polynomial differential system must belong to. We recall the characterization of systems which admit an elementary or ...

    • Zero-Hopf polynomial centers of third-order differential equations 

      García, I. A. (Isaac A.); Valls, Claudia (Springer Science+Business Media New York, 2016-11-15)
      We study the 3-dimensional center problem at the zero-Hopf singularity in some families of polynomial vector fields arising from third-order polynomial differential equations. After proving some general properties we check ...