Articles de revista
http://hdl.handle.net/2117/3918
2017-02-25T07:23:13ZThe group inverse of subdivision networks
http://hdl.handle.net/2117/101529
The group inverse of subdivision networks
Carmona Mejías, Ángeles; Mitjana Riera, Margarida; Monsó Burgués, Enrique P.J.
In this paper, given a network and a subdivision of it, we show how the Group Inverse of the subdivision network can be related to the Group Inverse of initial given network. Our approach establishes a relationship between solutions of related Poisson problems on both networks and takes advantatge on the definition of the Group Inverse matrix.
2017-02-24T11:50:56ZCarmona Mejías, ÁngelesMitjana Riera, MargaridaMonsó Burgués, Enrique P.J.In this paper, given a network and a subdivision of it, we show how the Group Inverse of the subdivision network can be related to the Group Inverse of initial given network. Our approach establishes a relationship between solutions of related Poisson problems on both networks and takes advantatge on the definition of the Group Inverse matrix.Functions and differentials on the non-split Cartan modular curve of level 11
http://hdl.handle.net/2117/101523
Functions and differentials on the non-split Cartan modular curve of level 11
Fernández González, Julio; González Rovira, Josep
The genus 4 modular curve Xns(11) attached to a non-split Cartan group of level 11
admits a model defined over Q. We compute generators for its function field in terms of
Siegel modular functions. We also show that its Jacobian is isomorphic over Q to the new
part of the Jacobian of the classical modular curve X0(121)
2017-02-24T10:48:02ZFernández González, JulioGonzález Rovira, JosepThe genus 4 modular curve Xns(11) attached to a non-split Cartan group of level 11
admits a model defined over Q. We compute generators for its function field in terms of
Siegel modular functions. We also show that its Jacobian is isomorphic over Q to the new
part of the Jacobian of the classical modular curve X0(121)Rigidity of infinitesimal momentum maps
http://hdl.handle.net/2117/101515
Rigidity of infinitesimal momentum maps
Miranda Galcerán, Eva; Esposito, Chiara
In this paper we prove rigidity theorems for Poisson Lie group actions on Poisson manifolds. In particular, we prove that close infinitesimal momentum maps associated to Poisson Lie group actions are equivalent using a normal form theorem for SCI spaces. When the Poisson structure of the acted manifold is integrable, this yields rigidity also for lifted actions to the symplectic groupoid.
2017-02-24T10:05:57ZMiranda Galcerán, EvaEsposito, ChiaraIn this paper we prove rigidity theorems for Poisson Lie group actions on Poisson manifolds. In particular, we prove that close infinitesimal momentum maps associated to Poisson Lie group actions are equivalent using a normal form theorem for SCI spaces. When the Poisson structure of the acted manifold is integrable, this yields rigidity also for lifted actions to the symplectic groupoid.Multiplier ideals in two-dimensional local rings with rational singularities
http://hdl.handle.net/2117/101436
Multiplier ideals in two-dimensional local rings with rational singularities
Alberich Carramiñana, Maria; Álvarez Montaner, Josep; Dachs Cadefau, Ferran
The aim of this paper is to study jumping numbers and multiplier ideals of any ideal in a two-dimensional local ring with a rational singularity. In particular we reveal which information encoded in a multiplier ideal determines the next jumping number. This leads to an algorithm to compute sequentially the jumping numbers and the whole chain of multiplier ideals in any desired range. As a consequence of our method we develop the notion of jumping divisor that allows to describe the jump between two consecutive multiplier ideals. In particular we find a unique minimal jumping divisor that is studied extensively.
2017-02-23T09:19:50ZAlberich Carramiñana, MariaÁlvarez Montaner, JosepDachs Cadefau, FerranThe aim of this paper is to study jumping numbers and multiplier ideals of any ideal in a two-dimensional local ring with a rational singularity. In particular we reveal which information encoded in a multiplier ideal determines the next jumping number. This leads to an algorithm to compute sequentially the jumping numbers and the whole chain of multiplier ideals in any desired range. As a consequence of our method we develop the notion of jumping divisor that allows to describe the jump between two consecutive multiplier ideals. In particular we find a unique minimal jumping divisor that is studied extensively.Arnold's mechanism of diffusion in the spatial circular restricted three-body problem: A semi-analytical argument
http://hdl.handle.net/2117/101125
Arnold's mechanism of diffusion in the spatial circular restricted three-body problem: A semi-analytical argument
Delshams Valdés, Amadeu; Gidea, Marian; Roldán, Pablo
We consider the spatial circular restricted three-body problem, on the motion of an infinitesimal body under the gravity of Sun and Earth. This can be described by a 3-degree of freedom Hamiltonian system. We fix an energy level close to that of the collinear libration point L1, located between Sun and Earth. Near L1 there exists a normally hyperbolic invariant manifold, diffeomorphic to a 3-sphere. For an orbit confined to this 3-sphere, the amplitude of the motion relative to the ecliptic (the plane of the orbits of Sun and Earth) can vary only slightly.
We show that we can obtain new orbits whose amplitude of motion relative to the ecliptic changes significantly, by following orbits of the flow restricted to the 3-sphere alternatively with homoclinic orbits that turn around the Earth. We provide an abstract theorem for the existence of such ‘diffusing’ orbits, and numerical evidence that the premises of the theorem are satisfied in the three-body problem considered here. We provide an explicit construction of diffusing orbits.
The geometric mechanism underlying this construction is reminiscent of the Arnold diffusion problem for Hamiltonian systems. Our argument, however, does not involve transition chains of tori as in the classical example of Arnold. We exploit mostly the ‘outer dynamics’ along homoclinic orbits, and use very little information on the ‘inner dynamics’ restricted to the 3-sphere.
As a possible application to astrodynamics, diffusing orbits as above can be used to design low cost maneuvers to change the inclination of an orbit of a satellite near L1 from a nearly-planar orbit to a tilted orbit with respect to the ecliptic. We explore different energy levels, and estimate the largest orbital inclination that can be achieved through our construction.
2017-02-16T09:57:15ZDelshams Valdés, AmadeuGidea, MarianRoldán, PabloWe consider the spatial circular restricted three-body problem, on the motion of an infinitesimal body under the gravity of Sun and Earth. This can be described by a 3-degree of freedom Hamiltonian system. We fix an energy level close to that of the collinear libration point L1, located between Sun and Earth. Near L1 there exists a normally hyperbolic invariant manifold, diffeomorphic to a 3-sphere. For an orbit confined to this 3-sphere, the amplitude of the motion relative to the ecliptic (the plane of the orbits of Sun and Earth) can vary only slightly.
We show that we can obtain new orbits whose amplitude of motion relative to the ecliptic changes significantly, by following orbits of the flow restricted to the 3-sphere alternatively with homoclinic orbits that turn around the Earth. We provide an abstract theorem for the existence of such ‘diffusing’ orbits, and numerical evidence that the premises of the theorem are satisfied in the three-body problem considered here. We provide an explicit construction of diffusing orbits.
The geometric mechanism underlying this construction is reminiscent of the Arnold diffusion problem for Hamiltonian systems. Our argument, however, does not involve transition chains of tori as in the classical example of Arnold. We exploit mostly the ‘outer dynamics’ along homoclinic orbits, and use very little information on the ‘inner dynamics’ restricted to the 3-sphere.
As a possible application to astrodynamics, diffusing orbits as above can be used to design low cost maneuvers to change the inclination of an orbit of a satellite near L1 from a nearly-planar orbit to a tilted orbit with respect to the ecliptic. We explore different energy levels, and estimate the largest orbital inclination that can be achieved through our construction.Diseño y construcción de un prototipo de plataforma Stewart
http://hdl.handle.net/2117/101116
Diseño y construcción de un prototipo de plataforma Stewart
Rossell Garriga, Josep Maria; Blanes Priego, Manel; Vicente Rodrigo, Jesús; Rubió Massegú, Josep; Palacios Quiñonero, Francisco
2017-02-15T16:31:47ZRossell Garriga, Josep MariaBlanes Priego, ManelVicente Rodrigo, JesúsRubió Massegú, JosepPalacios Quiñonero, Francisco30 anys del Seminari de Teoria de Nombres de Barcelona, STNB 2016
http://hdl.handle.net/2117/101086
30 anys del Seminari de Teoria de Nombres de Barcelona, STNB 2016
Alsina Aubach, Montserrat
2017-02-15T14:07:17ZAlsina Aubach, MontserratEn record de Jacqueline (Jackie) Anne Stedall (1950-2014)
http://hdl.handle.net/2117/101066
En record de Jacqueline (Jackie) Anne Stedall (1950-2014)
Massa Esteve, Maria Rosa
2017-02-15T10:55:05ZMassa Esteve, Maria RosaPredictive control of irrigation canals - robust design and real-time implementation
http://hdl.handle.net/2117/101064
Predictive control of irrigation canals - robust design and real-time implementation
Aguilar, Jose V.; Langarita, Pedro; Rodellar Benedé, José; Linares, Lorenzo; Horvath, Klaudia
Predictive control is one of the most commonly used control methods in a variety of application areas, including hydraulic processes such as water distribution canals for irrigation. This article presents the design and application of predictive control for the water discharge entering into an irrigation canal located in Spain. First, a discrete time linear model of the process is described and its parameters are experimentally identified. The model is well validated within the usual canal operating range and is used to formulate a predictive control law with an incremental formulation. Finally, experimental and simulation results are presented in which predictive control has shown better performance than a well-tuned proportional, integral and derivative controller to automatically manage demanded water discharges.
2017-02-15T10:32:46ZAguilar, Jose V.Langarita, PedroRodellar Benedé, JoséLinares, LorenzoHorvath, KlaudiaPredictive control is one of the most commonly used control methods in a variety of application areas, including hydraulic processes such as water distribution canals for irrigation. This article presents the design and application of predictive control for the water discharge entering into an irrigation canal located in Spain. First, a discrete time linear model of the process is described and its parameters are experimentally identified. The model is well validated within the usual canal operating range and is used to formulate a predictive control law with an incremental formulation. Finally, experimental and simulation results are presented in which predictive control has shown better performance than a well-tuned proportional, integral and derivative controller to automatically manage demanded water discharges.Warp evidence in precessing galactic bar models
http://hdl.handle.net/2117/101062
Warp evidence in precessing galactic bar models
Sanchez Martin, P; Romero Gómez, Mercè; Masdemont Soler, Josep
Most galaxies have a warped shape when they are seen edge-on. The reason for this curious form is not completely known so far, so in this work we apply dynamical system tools to contribute to its explanation. Starting from a simple, but realistic model formed by a bar and a disc, we study the effect of a small misalignment between the angular momentum of the system and its angular velocity. To this end, a precession model was developed and considered, assuming that the bar behaves like a rigid body. After checking that the periodic orbits inside the bar continue to be the skeleton of the inner system even after inflicting a precession to the potential, we computed the invariant manifolds of the unstable periodic orbits departing from the equilibrium points at the ends of the bar to find evidence of their warped shapes. As is well known, the invariant manifolds associated with these periodic orbits drive the arms and rings of barred galaxies and constitute the skeleton of these building blocks. Looking at them from a side-on viewpoint, we find that these manifolds present warped shapes like those recognised in observations. Lastly, test particle simulations have been performed to determine how the stars are affected by the applied precession, this way confirming the theoretical results.
2017-02-15T10:12:26ZSanchez Martin, PRomero Gómez, MercèMasdemont Soler, JosepMost galaxies have a warped shape when they are seen edge-on. The reason for this curious form is not completely known so far, so in this work we apply dynamical system tools to contribute to its explanation. Starting from a simple, but realistic model formed by a bar and a disc, we study the effect of a small misalignment between the angular momentum of the system and its angular velocity. To this end, a precession model was developed and considered, assuming that the bar behaves like a rigid body. After checking that the periodic orbits inside the bar continue to be the skeleton of the inner system even after inflicting a precession to the potential, we computed the invariant manifolds of the unstable periodic orbits departing from the equilibrium points at the ends of the bar to find evidence of their warped shapes. As is well known, the invariant manifolds associated with these periodic orbits drive the arms and rings of barred galaxies and constitute the skeleton of these building blocks. Looking at them from a side-on viewpoint, we find that these manifolds present warped shapes like those recognised in observations. Lastly, test particle simulations have been performed to determine how the stars are affected by the applied precession, this way confirming the theoretical results.