Ara es mostren els items 1-20 de 30

    • A K-contact Lagrangian formulation for nonconservative field theories 

      Gaset Rifà, Jordi; Gràcia Sabaté, Francesc Xavier; Muñoz Lecanda, Miguel Carlos; Rivas Guijarro, Xavier; Román Roy, Narciso (2021-06-01)
      Article
      Accés obert
      Dynamical systems with dissipative behaviour can be described in terms of contact manifolds and a modified version of Hamilton's equations. Dissipation terms can also be added to field equations, as showed in a recent paper ...
    • A summary on symmetries and conserved quantities of autonomous Hamiltonian systems 

      Román Roy, Narciso (AMER INST MATHEMATICAL SCIENCES-AIMS, 2020)
      Article
      Accés obert
      A complete geometric classification of symmetries of autonomous Hamiltonian systems is established; explaining how to obtain their associated conserved quantities in all cases. In particular, first we review well-known ...
    • Axiomàtica dels nombres reals 

      Aranda May, Montserrat (Universitat Politècnica de Catalunya, 2013-06)
      Treball Final de Grau
      Accés obert
      L'objectiu d'aquest treball és estudiar les propietats del conjunt de nombres reals, començant per una construcció d'aquest conjunt a través de classes d'equivalència de successions de Cauchy. Posteriorment, es prendrà ...
    • Constraint algorithm for k-presymplectic hamiltonian systems: application to singular field theories 

      Gràcia Sabaté, Francesc Xavier; Martín Grillo, Rubén; Román Roy, Narciso (World Scientific and Engineering Academy and Society (WSEAS), 2009-08-01)
      Article
      Accés obert
      The k-symplectic formulation of field theories is specially simple, since only tangent and cotangent bundles are needed in its description. Its defining elements show a close relationship with those in the symplectic formulation ...
    • Constraint algorithm for singular field theories in the k-cosymplectic framework 

      Gràcia Sabaté, Francesc Xavier; Rivas Guijarro, Xavier; Román Roy, Narciso (American Institute of Mathematical Sciences, 2020-03-15)
      Article
      Accés obert
      The aim of this paper is to develop a constraint algorithm for singular classical field theories in the framework of k-cosymplectic geometry. Since these field theories are singular, we need to introduce the notion of ...
    • Ferroelectrics as smart mechanical materials 

      Cordero Edwards, Kumara; Domingo Marimon, Neus; Abdollahi Hosnijeh, Amir; Sort Viñas, Jordi; Catalan, Gustau (2017-07-21)
      Article
      Accés obert
      The mechanical properties of materials are insensitive to space inversion, even when they are crystallographically asymmetric. In practice, this means that turning a piezoelectric crystal upside down or switching the ...
    • Galois: entre els radicals 

      Lario Loyo, Joan Carles (2012-10-03)
      Audiovisual
      Accés obert
    • Generic Galois extensions for SL_2(F_5) over Q 

      Plans Berenguer, Bernat (Mathematical Publishing, 2007)
      Article
      Accés obert
      Let $G_n$ be a double cover of either the alternating group $A_n$ or the symmetric group $S_n$, and let $G_{n-1}$ be the corresponding double cover of $A_{n-1}$ or $S_{n-1}$. For every odd $n\geq 3$ and every field $k$ of ...
    • Griffiths variational multisymplectic formulation for Lovelock gravity 

      Capriotti, Santiago; Gaset Rifà, Jordi; Román Roy, Narciso; Salomone, Leandro (2020-08-24)
      Article
      Accés obert
      This work is mainly devoted to constructing a multisymplectic description of Lovelock’s gravity, which is an extension of General Relativity. We establish the Griffiths variational problem for the Lovelock Lagrangian, ...
    • Grupos de Galois lineales provenientes de la geometría 

      Dieulefait, Luís V. (2013-03-06)
      Audiovisual
      Accés obert
    • Hamilton-Jacobi theory in multisymplectic classical field theories 

      De León, Manuel; Prieto Martínez, Pedro Daniel; Román Roy, Narciso; Vilariño Fernández, Silvia (2017-09-01)
      Article
      Accés obert
      The geometric framework for the Hamilton-Jacobi theory developed in the studies of Carinena et al. [Int. J. Geom. Methods Mod. Phys. 3(7), 1417-1458 (2006)], Carinena et al. [Int. J. Geom. Methods Mod. Phys. 13(2), 1650017 ...
    • Higher-order Cartan symmetries in k-symplectic field theory 

      Román Roy, Narciso; Salgado, Modesto; Vilariño, Silvia (2008-04-30)
      Article
      Accés obert
      For k-symplectic Hamiltonian field theories, we study infinitesimal transformations generated by certain kinds of vector fields which are not Noether symmetries, but which allow us to obtain conservation laws by means ...
    • Hopf Galois structures on symmetric and alternating extensions 

      Río Doval, Ana; Vela del Olmo, Maria Montserrat; Crespo Vicente, Teresa (2018)
      Article
      Accés obert
      By using a recent theorem by Koch, Kohl, Truman and Underwood on normality, we determine that some types of Hopf Galois structures do not occur on Galois extensions with Galois group isomorphic to alternating or symmetric ...
    • Induced Hopf Galois structures 

      Crespo Vicente, Teresa; Río Doval, Ana; Vela del Olmo, Maria Montserrat (2016-07-01)
      Article
      Accés obert
      For a ¿nite Galois extension K/k and an intermediate ¿eld F such that Gal(K/F)has a normal complement in Gal(K/k), we construct and characterize Hopf Galois structures on K/k which are induced by a pair of Hopf Galois ...
    • Induced Hopf Galois structures and their local Hopf Galois modules 

      Gil Muñoz, Daniel; Río Doval, Ana (2020-09)
      Article
      Accés obert
      The regular subgroup determining an induced Hopf Galois structure for a Galois extension L/K is obtained as direct product of the corresponding regular groups of the inducing subextensions. We describe here the attached ...
    • Inducing braces and Hopf Galois structures 

      Crespo, Teresa; Gil Muñoz, Daniel; Río Doval, Ana; Vela del Olmo, Maria Montserrat (2023-09-01)
      Article
      Accés obert
      Let p be a prime number and let n be an integer not divisible by p and such that every group of order np has a normal subgroup of order p. (This holds in particular for .) Under these hypotheses, we obtain a one-to-one ...
    • Lectura de la memòria sobre la resolubilitat de les equacions per radicals 

      Pla i Carrera, Josep (2013-03-06)
      Audiovisual
      Accés obert
    • More insights into symmetries in multisymplectic field theories 

      Guerra IV, Arnoldo; Román Roy, Narciso (2023-02-01)
      Article
      Accés obert
      This work provides a general overview for the treatment of symmetries in classical field theories and (pre)multisymplectic geometry. The geometric characteristics of the relation between how symmetries are interpreted in ...
    • Multicontact formulation for non-conservative field theories 

      de León Rodríguez, Manuel; Gaset Rifà, Jordi; Muñoz Lecanda, Miguel Carlos; Rivas Guijarro, Xavier; Román Roy, Narciso (Institute of Physics (IOP), 2023-01-13)
      Article
      Accés obert
      A new geometric structure inspired by multisymplectic and contact geometries, which we call multicontact structure, is developed to describe non-conservative classical field theories. Using the differential forms that ...
    • Multisymplectic Lagrangian and Hamiltonian formalisms of classical field theories 

      Román Roy, Narciso (2009)
      Article
      Accés obert
      This review paper is devoted to presenting the standard multisymplectic formulation for describing geometrically classical field theories, both the regular and singular cases. First, the main features of the Lagrangian ...