DSpace Collection:
http://hdl.handle.net/2117/3919
Thu, 05 Mar 2015 14:46:38 GMT20150305T14:46:38Zwebmaster.bupc@upc.eduUniversitat Politècnica de Catalunya. Servei de Biblioteques i DocumentaciónoApplications of numerical differentiation to computational plasticity
http://hdl.handle.net/2117/26511
Title: Applications of numerical differentiation to computational plasticity
Authors: Pérez Foguet, Agustí; Rodríguez Ferran, Antonio; Huerta, Antonio
Description: Report del Departament de Matemàtica Aplicada III  MA010Wed, 25 Feb 2015 13:30:29 GMThttp://hdl.handle.net/2117/2651120150225T13:30:29ZPérez Foguet, Agustí; Rodríguez Ferran, Antonio; Huerta, Antonionofinite element method, consistent tangent operators, difference scheme, flow vector, flow potential, quadratic convergenceModeling microwave drying of soils
http://hdl.handle.net/2117/26510
Title: Modeling microwave drying of soils
Authors: Pérez Foguet, Agustí; Huerta, Antonio
Description: Report del Departament de Matemàtica Aplicada III  MA009Wed, 25 Feb 2015 13:23:57 GMThttp://hdl.handle.net/2117/2651020150225T13:23:57ZPérez Foguet, Agustí; Huerta, Antonionosoil drying, microwave, suction, mathematical model, numerical simulationSingular solutions for a class of traveling wave equations arising in hydrodynamics
http://hdl.handle.net/2117/26450
Title: Singular solutions for a class of traveling wave equations arising in hydrodynamics
Authors: Geyer, Anna; Mañosa Fernández, Víctor
Abstract: We give an exhaustive characterization of singular weak solutions for ordinary
differential equations of the form $\ddot{u}\,u +
\frac{1}{2}\dot{u}^2 + F'(u) =0$, where $F$ is an analytic function.
Our motivation stems from the fact that in the context of hydrodynamics several
prominent equations are reducible to an equation of this form
upon passing to a moving frame. We construct peaked and cusped waves,
fronts with finitetime decay and compact solitary waves. We prove
that one cannot obtain peaked and compactly supported traveling waves for the
same equation. In particular, a peaked traveling wave cannot have compact
support and vice versa. To exemplify the approach we apply our
results to the CamassaHolm equation and the equation for surface waves
of moderate amplitude, and show how the different types of singular solutions
can be obtained varying the energy level of the corresponding planar Hamiltonian systems.
Description: PreprintFri, 20 Feb 2015 13:24:49 GMThttp://hdl.handle.net/2117/2645020150220T13:24:49ZGeyer, Anna; Mañosa Fernández, VíctornoCamassaHolm equation, integrable vector fields, singular ordinary differential equations, traveling waves.We give an exhaustive characterization of singular weak solutions for ordinary
differential equations of the form $\ddot{u}\,u +
\frac{1}{2}\dot{u}^2 + F'(u) =0$, where $F$ is an analytic function.
Our motivation stems from the fact that in the context of hydrodynamics several
prominent equations are reducible to an equation of this form
upon passing to a moving frame. We construct peaked and cusped waves,
fronts with finitetime decay and compact solitary waves. We prove
that one cannot obtain peaked and compactly supported traveling waves for the
same equation. In particular, a peaked traveling wave cannot have compact
support and vice versa. To exemplify the approach we apply our
results to the CamassaHolm equation and the equation for surface waves
of moderate amplitude, and show how the different types of singular solutions
can be obtained varying the energy level of the corresponding planar Hamiltonian systems.Lie symmetries of birational maps preserving genus 0 fibrations
http://hdl.handle.net/2117/26449
Title: Lie symmetries of birational maps preserving genus 0 fibrations
Authors: Llorens, Mireia; Mañosa Fernández, Víctor
Abstract: We prove that any planar birational integrable map, which preserves
a fibration given by genus $0$ curves has a Lie symmetry and some
associated invariant measures. The obtained results allow to study
in a systematic way the global dynamics of these maps. Using this
approach, the dynamics of several maps is described. In particular
we are able to give, for particular examples, the explicit
expression of the rotation number function, and the set of periods
of the considered maps.
Description: Preprint.Fri, 20 Feb 2015 12:54:58 GMThttp://hdl.handle.net/2117/2644920150220T12:54:58ZLlorens, Mireia; Mañosa Fernández, VíctornoIntegrable maps, Lie symmetries, Periodic
orbits, Rational parameterizations.We prove that any planar birational integrable map, which preserves
a fibration given by genus $0$ curves has a Lie symmetry and some
associated invariant measures. The obtained results allow to study
in a systematic way the global dynamics of these maps. Using this
approach, the dynamics of several maps is described. In particular
we are able to give, for particular examples, the explicit
expression of the rotation number function, and the set of periods
of the considered maps.Actionangle variables and a KAM theorem for bPoisson manifolds
http://hdl.handle.net/2117/26390
Title: Actionangle variables and a KAM theorem for bPoisson manifolds
Authors: Kiesenhofer, Anna; Miranda Galcerán, Eva; Scott, Geoffrey
Abstract: In this article we prove an actionangle theorem for bintegrable systems on bPoisson manifolds improving the actionangle theorem contained in [LMV11] for general Poisson manifolds in this setting. As an application, we prove a KAMtype theorem for bPoisson manifolds.Tue, 17 Feb 2015 12:12:30 GMThttp://hdl.handle.net/2117/2639020150217T12:12:30ZKiesenhofer, Anna; Miranda Galcerán, Eva; Scott, GeoffreynoIn this article we prove an actionangle theorem for bintegrable systems on bPoisson manifolds improving the actionangle theorem contained in [LMV11] for general Poisson manifolds in this setting. As an application, we prove a KAMtype theorem for bPoisson manifolds.Analysis of the vane test considering size and time effects
http://hdl.handle.net/2117/25608
Title: Analysis of the vane test considering size and time effects
Authors: Pérez Foguet, Agustí; Ledesma Villalba, Alberto; Huerta, Antonio
Description: CIMNE  PI 122Thu, 15 Jan 2015 12:17:58 GMThttp://hdl.handle.net/2117/2560820150115T12:17:58ZPérez Foguet, Agustí; Ledesma Villalba, Alberto; Huerta, AntonionoConsistent tangent matrices for substepping schemes
http://hdl.handle.net/2117/25607
Title: Consistent tangent matrices for substepping schemes
Authors: Pérez Foguet, Agustí; Rodríguez Ferran, Antonio; Huerta, Antonio
Abstract: A very simple and general expression of the consistent tangent matrix for substep
ping timeintegration schemes is presented. If needed, the derivatives required for
the computation of the consistent tangent moduli can be obtained via numerical dif
ferentiation. These two strategies (substepping and numerical differentiation) lead
to quadratic convergence in complex nonlinear inelasticity problems.
Description: CIMNE  PI 174Thu, 15 Jan 2015 12:14:15 GMThttp://hdl.handle.net/2117/2560720150115T12:14:15ZPérez Foguet, Agustí; Rodríguez Ferran, Antonio; Huerta, AntonionoFinite element method, computational plasticity, quadratic
convergence, substepping, numerical differentiation, nonlinear problemsA very simple and general expression of the consistent tangent matrix for substep
ping timeintegration schemes is presented. If needed, the derivatives required for
the computation of the consistent tangent moduli can be obtained via numerical dif
ferentiation. These two strategies (substepping and numerical differentiation) lead
to quadratic convergence in complex nonlinear inelasticity problems.Numerical differentiation for local and global tangent operators in computational plasticity
http://hdl.handle.net/2117/25606
Title: Numerical differentiation for local and global tangent operators in computational plasticity
Authors: Pérez Foguet, Agustí; Rodríguez Ferran, Antonio; Huerta, Antonio
Abstract: In this paper, numerical differentiation is applied to integrate plastic constitutive
laws and to compute the corresponding consistent tangent operators. The deriva
tivesoftheconstitutive equationsareapproximatedbymeansofdifferenceschemes.
These derivatives are needed to achieve quadratic convergence in the integration at
Gausspoint level and in the solution of the boundary value problem. Numerical
differentiation is shown to be a simple, robust and competitive alternative to an
alytical derivatives. Quadratic convergence is maintained, provided that adequate
schemes and stepsizes are chosen. This point is illustrated by means of some nu
merical examples.
Description: CIMNE  PI 144Thu, 15 Jan 2015 12:09:11 GMThttp://hdl.handle.net/2117/2560620150115T12:09:11ZPérez Foguet, Agustí; Rodríguez Ferran, Antonio; Huerta, Antonionofinite element method, consistent tangent operators, numerical
differentiation, difference schemes, quadratic convergenceIn this paper, numerical differentiation is applied to integrate plastic constitutive
laws and to compute the corresponding consistent tangent operators. The deriva
tivesoftheconstitutive equationsareapproximatedbymeansofdifferenceschemes.
These derivatives are needed to achieve quadratic convergence in the integration at
Gausspoint level and in the solution of the boundary value problem. Numerical
differentiation is shown to be a simple, robust and competitive alternative to an
alytical derivatives. Quadratic convergence is maintained, provided that adequate
schemes and stepsizes are chosen. This point is illustrated by means of some nu
merical examples.Xiao's conjuecture for general fibred surfaces
http://hdl.handle.net/2117/24999
Title: Xiao's conjuecture for general fibred surfaces
Authors: Barja Yáñez, Miguel Ángel; González Alonso, Víctor; Naranjo del Val, Joan Carles
Abstract: We prove that the genus g, the relative irregularity q_f and the Clifford index c_f of a nonisotrivial fibration
f satisfy the inequality q_f=gc_f. This gives in particular a proof of Xiao’s conjecture for
fibrations whose general fibres have maximal Clifford index.
Description: PrerpintThu, 11 Dec 2014 12:05:29 GMThttp://hdl.handle.net/2117/2499920141211T12:05:29ZBarja Yáñez, Miguel Ángel; González Alonso, Víctor; Naranjo del Val, Joan CarlesnoFibration
Slope
Xiao's conjecture
Clifford IndexWe prove that the genus g, the relative irregularity q_f and the Clifford index c_f of a nonisotrivial fibration
f satisfy the inequality q_f=gc_f. This gives in particular a proof of Xiao’s conjecture for
fibrations whose general fibres have maximal Clifford index.Stability and singularities of relative hypersurfaces
http://hdl.handle.net/2117/24998
Title: Stability and singularities of relative hypersurfaces
Authors: Barja Yáñez, Miguel Ángel; Stoppino, Lidia
Abstract: We study relative hypersurfaces, and prove an instability condition for the fibres. This
is the starting point for an investigation of the geometry of effective divisors on relative
projective bundles.Thu, 11 Dec 2014 12:01:17 GMThttp://hdl.handle.net/2117/2499820141211T12:01:17ZBarja Yáñez, Miguel Ángel; Stoppino, LidianoSlope
Hypersurfaces
StabilityWe study relative hypersurfaces, and prove an instability condition for the fibres. This
is the starting point for an investigation of the geometry of effective divisors on relative
projective bundles.Algebraic description of Jacobians isogeneous to certain Prym varieties with polarization (1,2)
http://hdl.handle.net/2117/24994
Title: Algebraic description of Jacobians isogeneous to certain Prym varieties with polarization (1,2)
Authors: Fedorov, Yuri; Enolski, Viktor Z.
Abstract: For a class of nonhyperelliptic genus 3 curves C which are 2fold coverings of elliptic curves E, we give an explicit algebraic description of all birationally nonequivalent genus 2 curves whose Jacobians are degree 2 isogeneous to the Prym varieties associated to such coverings. Our description is based on previous studies of Prym varieties with polarization (1,2) in connection with separation of variables in a series of classical and new algebraic integrable systems linearized on such varieties.
We also consider some special cases of the covering C > E, in particular, when the corresponding Prym varieties contain pairs of elliptic curves and the Jacobian of C is isogeneous (but not isomorphic) to the product of 3 different elliptic curves.
Our description is accompanied with explicit numerical examplesThu, 11 Dec 2014 08:09:29 GMThttp://hdl.handle.net/2117/2499420141211T08:09:29ZFedorov, Yuri; Enolski, Viktor Z.noFor a class of nonhyperelliptic genus 3 curves C which are 2fold coverings of elliptic curves E, we give an explicit algebraic description of all birationally nonequivalent genus 2 curves whose Jacobians are degree 2 isogeneous to the Prym varieties associated to such coverings. Our description is based on previous studies of Prym varieties with polarization (1,2) in connection with separation of variables in a series of classical and new algebraic integrable systems linearized on such varieties.
We also consider some special cases of the covering C > E, in particular, when the corresponding Prym varieties contain pairs of elliptic curves and the Jacobian of C is isogeneous (but not isomorphic) to the product of 3 different elliptic curves.
Our description is accompanied with explicit numerical examplesRigidity of Poisson Lie group actions
http://hdl.handle.net/2117/24632
Title: Rigidity of Poisson Lie group actions
Authors: Miranda Galcerán, Eva
Abstract: n this paper we prove that close infinitesimal momentum maps associated to Poisson Lie actions are equivalent under some mild assumptions. We also obtain rigidity theorems for actual momentum maps (when the acting Lie group G is endowed with an arbitrary Poisson structure) combining a rigidity result for canonical Hamiltonian actions (\cite{MMZ}) and a linearization theorem(\cite{GW}). These results have applications to quantization of symmetries since these infinitesimal momentum maps appear as the classical limit of quantum momentum maps (\cite{BEN}).Mon, 10 Nov 2014 12:51:24 GMThttp://hdl.handle.net/2117/2463220141110T12:51:24ZMiranda Galcerán, Evanon this paper we prove that close infinitesimal momentum maps associated to Poisson Lie actions are equivalent under some mild assumptions. We also obtain rigidity theorems for actual momentum maps (when the acting Lie group G is endowed with an arbitrary Poisson structure) combining a rigidity result for canonical Hamiltonian actions (\cite{MMZ}) and a linearization theorem(\cite{GW}). These results have applications to quantization of symmetries since these infinitesimal momentum maps appear as the classical limit of quantum momentum maps (\cite{BEN}).Extended version. Occurrence of solar flares viewed with GPS: statistics and fractal nature
http://hdl.handle.net/2117/24607
Title: Extended version. Occurrence of solar flares viewed with GPS: statistics and fractal nature
Authors: Monte Moreno, Enrique; Hernández Pajares, Manuel
Abstract: In this paper we describe the statistical properties of the EUV solar flux sudden variation. The solar flux variation is modeled as a time series characterized by the subsolar VTEC (Vertical Total Electron Content) doubledifference in time, computed with dual frequency GNSS (Global Navigation Satellite System) measurements in the daylight hemisphere. By assuming a sudden overionization pattern of solar origin, during the last solar cycle, we propose a model that explains it's characteristics, and the forecasting limitations. The two defining characteristics of this time series, is an extreme variability (i.e.\ in a solar cycle one can find events at $400 \sigma$ from the mean value) and a temporal correlation that is independent of the time scale. We give a characterization of a model that explains the empirical results, and properties such as, a) the persistence and presence of bursts of solar flares, b) their long tail peak values of the solar flux variation. We show that the solar flux variation time series can be characterized by a fractional Brownian model for the long term dependence, and a powerlaw distribution for the extreme values that appear in the time series.
Description: Extended version of the paperFri, 07 Nov 2014 14:46:29 GMThttp://hdl.handle.net/2117/2460720141107T14:46:29ZMonte Moreno, Enrique; Hernández Pajares, ManuelnoSolar Flares, Fractal, Global Possioning System, GPS, statistics, MandelbrotIn this paper we describe the statistical properties of the EUV solar flux sudden variation. The solar flux variation is modeled as a time series characterized by the subsolar VTEC (Vertical Total Electron Content) doubledifference in time, computed with dual frequency GNSS (Global Navigation Satellite System) measurements in the daylight hemisphere. By assuming a sudden overionization pattern of solar origin, during the last solar cycle, we propose a model that explains it's characteristics, and the forecasting limitations. The two defining characteristics of this time series, is an extreme variability (i.e.\ in a solar cycle one can find events at $400 \sigma$ from the mean value) and a temporal correlation that is independent of the time scale. We give a characterization of a model that explains the empirical results, and properties such as, a) the persistence and presence of bursts of solar flares, b) their long tail peak values of the solar flux variation. We show that the solar flux variation time series can be characterized by a fractional Brownian model for the long term dependence, and a powerlaw distribution for the extreme values that appear in the time series.Lyubeznik numbers of local rings and linear strands of graded ideals
http://hdl.handle.net/2117/24185
Title: Lyubeznik numbers of local rings and linear strands of graded ideals
Authors: Álvarez Montaner, Josep; Yanagawa, Kohji
Abstract: n this work we intro duce a new set of invariants asso ciated to the linear
strands of a minimal free resolution of a
Z
graded ideal
I
R
=

[
x
1
;:::;x
n
]
. We
also prove that these invariants satisfy some prop erties analogous to those of Lyub eznik
numb ers of lo cal rings. In particular, they satisfy a consecutiveness prop erty that we
prove rst for Lyub eznik numb ers. For the case of squarefree monomial ideals we get
more insight on the relation b etween Lyub eznik numb ers and the linear strands of their
asso ciated Alexander dual ideals. Finally, we prove that Lyub eznik numb ers of Stanley
Reisner rings are not only an algebraic invariant but also a top ological invariant, meaning
that they dep end on the homeomorphic class of the geometric realization of the asso ciated
simplicial complex and the characteristic of the base fieldTue, 30 Sep 2014 09:46:24 GMThttp://hdl.handle.net/2117/2418520140930T09:46:24ZÁlvarez Montaner, Josep; Yanagawa, Kohjinon this work we intro duce a new set of invariants asso ciated to the linear
strands of a minimal free resolution of a
Z
graded ideal
I
R
=

[
x
1
;:::;x
n
]
. We
also prove that these invariants satisfy some prop erties analogous to those of Lyub eznik
numb ers of lo cal rings. In particular, they satisfy a consecutiveness prop erty that we
prove rst for Lyub eznik numb ers. For the case of squarefree monomial ideals we get
more insight on the relation b etween Lyub eznik numb ers and the linear strands of their
asso ciated Alexander dual ideals. Finally, we prove that Lyub eznik numb ers of Stanley
Reisner rings are not only an algebraic invariant but also a top ological invariant, meaning
that they dep end on the homeomorphic class of the geometric realization of the asso ciated
simplicial complex and the characteristic of the base fieldA methodology for obtaining asymptotic estimates for the exponentially small splitting of separatrices to whiskered tori with quadratic frequencies
http://hdl.handle.net/2117/24155
Title: A methodology for obtaining asymptotic estimates for the exponentially small splitting of separatrices to whiskered tori with quadratic frequencies
Authors: Delshams Valdés, Amadeu; Gonchenko, Marina; Gutiérrez Serrés, PereThu, 25 Sep 2014 08:12:02 GMThttp://hdl.handle.net/2117/2415520140925T08:12:02ZDelshams Valdés, Amadeu; Gonchenko, Marina; Gutiérrez Serrés, Pereno