DSpace Community:
http://hdl.handle.net/2117/3558
Mon, 26 Jan 2015 23:15:53 GMT2015-01-26T23:15:53Zwebmaster.bupc@upc.eduUniversitat Politècnica de Catalunya. Servei de Biblioteques i DocumentaciónoA new approach to the vakonomic mechanics
http://hdl.handle.net/2117/24993
Title: A new approach to the vakonomic mechanics
Authors: Llibre Saló, Jaume; Ramírez Ros, Rafael; Sadovskaia Nurimanova, Natalia Guennadievna
Abstract: The aim of this paper was to show that the Lagrange-d'Alembert and its equivalent the Gauss and Appel principle are not the only way to deduce the equations of motion of the nonholonomic systems. Instead of them we consider the generalization of the Hamiltonian principle for nonholonomic systems with non-zero transpositional relations. We apply this variational principle, which takes into the account transpositional relations different from the classical ones, and we deduce the equations of motion for the nonholonomic systems with constraints that in general are nonlinear in the velocity. These equations of motion coincide, except perhaps in a zero Lebesgue measure set, with the classical differential equations deduced with the d'Alembert-Lagrange principle. We provide a new point of view on the transpositional relations for the constrained mechanical systems: the virtual variations can produce zero or non-zero transpositional relations. In particular, the independent virtual variations can produce non-zero transpositional relations. For the unconstrained mechanical systems, the virtual variations always produce zero transpositional relations. We conjecture that the existence of the nonlinear constraints in the velocity must be sought outside of the Newtonian mechanics. We illustrate our results with examples.Thu, 11 Dec 2014 08:01:15 GMThttp://hdl.handle.net/2117/249932014-12-11T08:01:15ZLlibre Saló, Jaume; Ramírez Ros, Rafael; Sadovskaia Nurimanova, Natalia GuennadievnanoVariational principle, Generalized Hamiltonian principle, d'Alembert-Lagrange principle, Constrained Lagrangian system, Transpositional relations, Vakonomic mechanic, Equation of motion, Vorones system, Chapligyn system, Newtonian model, NONHOLONOMIC SYSTEMS, CONSTRAINED SYSTEMS, DYNAMICS, REALIZATION, PRINCIPLE, GEOMETRYThe aim of this paper was to show that the Lagrange-d'Alembert and its equivalent the Gauss and Appel principle are not the only way to deduce the equations of motion of the nonholonomic systems. Instead of them we consider the generalization of the Hamiltonian principle for nonholonomic systems with non-zero transpositional relations. We apply this variational principle, which takes into the account transpositional relations different from the classical ones, and we deduce the equations of motion for the nonholonomic systems with constraints that in general are nonlinear in the velocity. These equations of motion coincide, except perhaps in a zero Lebesgue measure set, with the classical differential equations deduced with the d'Alembert-Lagrange principle. We provide a new point of view on the transpositional relations for the constrained mechanical systems: the virtual variations can produce zero or non-zero transpositional relations. In particular, the independent virtual variations can produce non-zero transpositional relations. For the unconstrained mechanical systems, the virtual variations always produce zero transpositional relations. We conjecture that the existence of the nonlinear constraints in the velocity must be sought outside of the Newtonian mechanics. We illustrate our results with examples.Emotional inertia: a key to understanding psychotherapy process and outcome
http://hdl.handle.net/2117/24368
Title: Emotional inertia: a key to understanding psychotherapy process and outcome
Authors: Bornas Agustí, F. Xavier; Noguera Batlle, Miquel; Pincus, David; Buela Casal, Gualberto
Abstract: The processes underlying psychotherapeutic change have increasingly been emphasized in both research and clinical practice. Nonlinear dynamical systems theory (NDS) offers a transdisciplinary scientific approach to the study of these processes. This paper introduces the NDS concept ofTue, 14 Oct 2014 17:39:56 GMThttp://hdl.handle.net/2117/243682014-10-14T17:39:56ZBornas Agustí, F. Xavier; Noguera Batlle, Miquel; Pincus, David; Buela Casal, GualbertonoPsychotherapy outcome, Psychotherapy process, Emotional inertia, Dynamical systems, Theoretical study, Behavioral-therapy, Innovative moments, Disorder, ModelsThe processes underlying psychotherapeutic change have increasingly been emphasized in both research and clinical practice. Nonlinear dynamical systems theory (NDS) offers a transdisciplinary scientific approach to the study of these processes. This paper introduces the NDS concept ofAn improvement of Ostrowski root-finding method
http://hdl.handle.net/2117/18913
Title: An improvement of Ostrowski root-finding method
Authors: Grau Sánchez, Miguel; Díaz Barrero, José Luis
Abstract: An improvement to the iterative method based on the Ostrowski one to compute nonlinear equation solutions, which increases the local order of convergence is suggested. The adaptation of a strategy presented here gives a new iteration function with an additional evaluation of the function. It also shows a smaller cost if we use adaptive multi-precision arithmetic. The numerical results computed using this system with a floating point system representing 200 decimal digits support this theory.
Description: "Applied Mathematics and Computation Top Cited Article 2005-2010"Mon, 22 Apr 2013 10:46:22 GMThttp://hdl.handle.net/2117/189132013-04-22T10:46:22ZGrau Sánchez, Miguel; Díaz Barrero, José LuisnoAn improvement to the iterative method based on the Ostrowski one to compute nonlinear equation solutions, which increases the local order of convergence is suggested. The adaptation of a strategy presented here gives a new iteration function with an additional evaluation of the function. It also shows a smaller cost if we use adaptive multi-precision arithmetic. The numerical results computed using this system with a floating point system representing 200 decimal digits support this theory.Theoretical dark matter halo kinematics and triaxial shape
http://hdl.handle.net/2117/17510
Title: Theoretical dark matter halo kinematics and triaxial shape
Authors: Salvador-Solé, Eduard; Serra, Sinué; Manrique, Alberto; González Casado, Guillermo
Abstract: In a recent paper, Salvador-Solé et al. have derived the typical inner structure of dark matter haloes from that of peaks in the initial random Gaussian density field, determined by the power spectrum of density perturbations characterizing the hierarchical cosmology under consideration. In this paper, we extend this formalism to the typical kinematics and triaxial shape of haloes. Specifically, we establish the link between such halo properties and the power spectrum of density perturbations through the typical shape of peaks. The trends of the
predicted typical halo shape, pseudo-phase-space density and anisotropy profiles are in good agreement with the results of numerical simulations. Our model sheds light on the origin of the power-law-like pseudo-phase-space density profile for virialized haloes.Thu, 24 Jan 2013 13:19:32 GMThttp://hdl.handle.net/2117/175102013-01-24T13:19:32ZSalvador-Solé, Eduard; Serra, Sinué; Manrique, Alberto; González Casado, GuillermonoIn a recent paper, Salvador-Solé et al. have derived the typical inner structure of dark matter haloes from that of peaks in the initial random Gaussian density field, determined by the power spectrum of density perturbations characterizing the hierarchical cosmology under consideration. In this paper, we extend this formalism to the typical kinematics and triaxial shape of haloes. Specifically, we establish the link between such halo properties and the power spectrum of density perturbations through the typical shape of peaks. The trends of the
predicted typical halo shape, pseudo-phase-space density and anisotropy profiles are in good agreement with the results of numerical simulations. Our model sheds light on the origin of the power-law-like pseudo-phase-space density profile for virialized haloes.Dynamical behavior of asteroids near resonance: the 4:1 gap and the 7:2 group
http://hdl.handle.net/2117/14731
Title: Dynamical behavior of asteroids near resonance: the 4:1 gap and the 7:2 group
Authors: Grau Sánchez, Miguel; González Casado, Guillermo
Abstract: A comparative study of the evolution of the Sun–Jupiter–Asteroid system near the 4:1
and 7:2 resonances is performed by means of two techniques that proceed differently from the
Hamiltonian corresponding to the planar restricted elliptic three-body problem. One technique is
based on the classical Schubart averaging while the other is based on a mapping method in which
the perturbing part of the Hamiltonian is expanded and the resulting terms are ordered according to
a weight function that depends on the powers of eccentricities and the coefficients of the terms. For
the mapping method the effect of Saturn on the asteroidal evolution is introduced and the degree of
chaos is estimated by means of the Lyapunov time. Both methods are shown to lead to similar results
and can be considered a suitable tool for describing the evolution of asteroids in the Kirkwood gap
and the group corresponding to the 4:1 and 7:2 Jovian resonances, respectively.Mon, 23 Jan 2012 10:59:32 GMThttp://hdl.handle.net/2117/147312012-01-23T10:59:32ZGrau Sánchez, Miguel; González Casado, GuillermonoA comparative study of the evolution of the Sun–Jupiter–Asteroid system near the 4:1
and 7:2 resonances is performed by means of two techniques that proceed differently from the
Hamiltonian corresponding to the planar restricted elliptic three-body problem. One technique is
based on the classical Schubart averaging while the other is based on a mapping method in which
the perturbing part of the Hamiltonian is expanded and the resulting terms are ordered according to
a weight function that depends on the powers of eccentricities and the coefficients of the terms. For
the mapping method the effect of Saturn on the asteroidal evolution is introduced and the degree of
chaos is estimated by means of the Lyapunov time. Both methods are shown to lead to similar results
and can be considered a suitable tool for describing the evolution of asteroids in the Kirkwood gap
and the group corresponding to the 4:1 and 7:2 Jovian resonances, respectively.Origin and modelling of cold dark matter halo properties: IV. Triaxial ellipticity
http://hdl.handle.net/2117/14392
Title: Origin and modelling of cold dark matter halo properties: IV. Triaxial ellipticity
Authors: Salvador-Solé, Eduard; Serra, Sinué; Manrique, Alberto; González Casado, Guillermo
Abstract: In the three preceding papers in the series, we presented a model dealing with the
global and small-scale structure and kinematics of hierarchically assembled, virialised,
collisionless systems, which correctly accounted for the typical properties of simulated
cold darkmatter (CDM) haloes. This model relied, however, on the spherical symmetry
assumption. Here we show that the foundations of the model hold equally well for
triaxial systems and extend it in a fully accurate way to objects that satisfy the latter
more general symmetry. The master equations in the new version take the same form
as in the version for spherically symmetric objects, but the profiles of all the physical
quantities are replaced by their respective spherical averages. All the consequences
of the model drawn under the spherical symmetry assumption continue to hold. In
addition, the new version allows one to infer the axial ratios of virialised ellipsoids from
those of the corresponding protoobjects. The present results generalise and validate
those obtained in Papers I, II and III for CDM haloes. In particular, they confirm that
all halo properties are the natural consequence of haloes evolving through accretion
and major mergers from triaxial peaks (secondary maxima) in the primordial density
field.Mon, 02 Jan 2012 12:38:30 GMThttp://hdl.handle.net/2117/143922012-01-02T12:38:30ZSalvador-Solé, Eduard; Serra, Sinué; Manrique, Alberto; González Casado, GuillermonoIn the three preceding papers in the series, we presented a model dealing with the
global and small-scale structure and kinematics of hierarchically assembled, virialised,
collisionless systems, which correctly accounted for the typical properties of simulated
cold darkmatter (CDM) haloes. This model relied, however, on the spherical symmetry
assumption. Here we show that the foundations of the model hold equally well for
triaxial systems and extend it in a fully accurate way to objects that satisfy the latter
more general symmetry. The master equations in the new version take the same form
as in the version for spherically symmetric objects, but the profiles of all the physical
quantities are replaced by their respective spherical averages. All the consequences
of the model drawn under the spherical symmetry assumption continue to hold. In
addition, the new version allows one to infer the axial ratios of virialised ellipsoids from
those of the corresponding protoobjects. The present results generalise and validate
those obtained in Papers I, II and III for CDM haloes. In particular, they confirm that
all halo properties are the natural consequence of haloes evolving through accretion
and major mergers from triaxial peaks (secondary maxima) in the primordial density
field.A technique to composite a modified Newton's method for solving nonlinear equations
http://hdl.handle.net/2117/12477
Title: A technique to composite a modified Newton's method for solving nonlinear equations
Authors: Grau Sánchez, Miguel; Díaz Barrero, José Luis
Abstract: A zero-finding technique for solving nonlinear equations more efficiently than they usually are with traditional iterative methods in which the order of convergence is
improved is presented. The key idea in deriving this procedure is to compose a
given iterative method with a modified Newton’s method that introduces just one
evaluation of the function. To carry out this procedure some classical methods with
different orders of convergence are used to obtain root-finders with higher efficiency
index.
Description: Nova tècnica que permet construir mètodes iteratius d'ordre alt.Thu, 05 May 2011 11:44:52 GMThttp://hdl.handle.net/2117/124772011-05-05T11:44:52ZGrau Sánchez, Miguel; Díaz Barrero, José LuisnoA zero-finding technique for solving nonlinear equations more efficiently than they usually are with traditional iterative methods in which the order of convergence is
improved is presented. The key idea in deriving this procedure is to compose a
given iterative method with a modified Newton’s method that introduces just one
evaluation of the function. To carry out this procedure some classical methods with
different orders of convergence are used to obtain root-finders with higher efficiency
index.On computational order of convergence of some multi-precision solvers of nonlinear systems of equations
http://hdl.handle.net/2117/12475
Title: On computational order of convergence of some multi-precision solvers of nonlinear systems of equations
Authors: Grau Sánchez, Miguel; Grau Gotés, Mª Ángela; Díaz Barrero, José Luis
Abstract: In this paper the local order of convergence used in iterative methods to solve nonlinear systems of equations is revisited, where shorter alternative analytic proofs of the order based on developments of multilineal functions are shown. Most important, an adaptive multi-precision arithmetics is used hereof, where in each step the length of the mantissa is defined independently of the knowledge of the root.
Furthermore, generalizations of the one dimensional case to m-dimensions of three approximations of computational order of convergence are defined. Examples illustrating the previous results are given.
Description: Report d'un treball de recerca on es presenten noves tècniques de càlcul de l'ordre de convergència amb una aritmètica adaptativa.Thu, 05 May 2011 11:25:05 GMThttp://hdl.handle.net/2117/124752011-05-05T11:25:05ZGrau Sánchez, Miguel; Grau Gotés, Mª Ángela; Díaz Barrero, José LuisnoIn this paper the local order of convergence used in iterative methods to solve nonlinear systems of equations is revisited, where shorter alternative analytic proofs of the order based on developments of multilineal functions are shown. Most important, an adaptive multi-precision arithmetics is used hereof, where in each step the length of the mantissa is defined independently of the knowledge of the root.
Furthermore, generalizations of the one dimensional case to m-dimensions of three approximations of computational order of convergence are defined. Examples illustrating the previous results are given.Uso de sismogramas antiguos para el estudio de paràmetros focales de terremotos ibèricos.
http://hdl.handle.net/2117/12274
Title: Uso de sismogramas antiguos para el estudio de paràmetros focales de terremotos ibèricos.
Authors: Batlló Ortiz, Josep; Teves-Costa, Paula; Stich, Daniel; Macià Jové, Ramon; Morales Soto, JoseWed, 06 Apr 2011 09:42:21 GMThttp://hdl.handle.net/2117/122742011-04-06T09:42:21ZBatlló Ortiz, Josep; Teves-Costa, Paula; Stich, Daniel; Macià Jové, Ramon; Morales Soto, JosenoOn the 16th Hilbert problem for limit cycles on nonsingular algebraic curves
http://hdl.handle.net/2117/12028
Title: On the 16th Hilbert problem for limit cycles on nonsingular algebraic curves
Authors: Llibre Saló, Jaume; Ramírez Inostroza, Rafael Orlando; Sadovskaia Nurimanova, Natalia Guennadievna
Abstract: 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. Additionally we provide sufficient conditions in order that all the algebraic limit cycles are hyperbolic. We also provide lower bounds for N.Wed, 23 Mar 2011 10:34:46 GMThttp://hdl.handle.net/2117/120282011-03-23T10:34:46ZLlibre Saló, Jaume; Ramírez Inostroza, Rafael Orlando; Sadovskaia Nurimanova, Natalia GuennadievnanoWe 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. Additionally we provide sufficient conditions in order that all the algebraic limit cycles are hyperbolic. We also provide lower bounds for N.Estudi de la transformació de l'espai de color RGB a l'espai de color HSV
http://hdl.handle.net/2117/12013
Title: Estudi de la transformació de l'espai de color RGB a l'espai de color HSV
Authors: Grau Gotés, Mª Ángela; Grau Sánchez, Miguel; Montseny Masip, Eduard; Sobrevilla Frisón, Pilar
Abstract: S’apliquen les tècniques clàssiques de propagació de l’error a la transformació de l’espai de color RGB en l’espai de color HSV a un conjunt de 1098 imatges test. El conjunt d’imatges test són 183 paletes de color i sis nivells d’il·luminació diferents. Els resultats que es presenten indiquen com varien la mitjana i la variància per la transformació.Tue, 22 Mar 2011 10:51:28 GMThttp://hdl.handle.net/2117/120132011-03-22T10:51:28ZGrau Gotés, Mª Ángela; Grau Sánchez, Miguel; Montseny Masip, Eduard; Sobrevilla Frisón, PilarnoS’apliquen les tècniques clàssiques de propagació de l’error a la transformació de l’espai de color RGB en l’espai de color HSV a un conjunt de 1098 imatges test. El conjunt d’imatges test són 183 paletes de color i sis nivells d’il·luminació diferents. Els resultats que es presenten indiquen com varien la mitjana i la variància per la transformació.Linear and nonlinear analyses of EEG dynamics during non-painful somatosensory processing in chronic pain patients
http://hdl.handle.net/2117/10129
Title: Linear and nonlinear analyses of EEG dynamics during non-painful somatosensory processing in chronic pain patients
Authors: Sitges, Carolina; Bornas, Xavier; Llabrés, Jordi; Noguera Batlle, Miquel; Montoya, Pedro
Abstract: The aim of our study was to characterize brain dynamics of affective modulation of somatosensory processing in chronic pain. We hypothesized that chronic pain patients will show abnormal EEG activity under negative mood conditions compared to healthly controls. Nineteen patients with chronic pain and 21 healthy subjects participated in the experiment. Multiscale entropy, fractal dimension, event-related potentials, and fast Fourier trasnform were used to analyze EEG data. A significant enhancement of entropy was found in pain patients were viewing unpleasant pictures. By contrast, no signifiant differences due to hemisphere or affective condition were found on nonlinear measures for healthy controls. Analyses of somatosensory ERPs showed that P50 amplitudes elicited by pleasant pictures were more reduced in chronic pain patients than in healthy controls. Finally, we observed that EEG band power was lower in pain patients than in healthy controls, in particular for theta and beata bands over sensorimotor cortices and temporal regions when viewing pleasant images. These findings suggest that sustained pain seems to be accompanied by an abnormal activation and dynamic of brain netwoork related to emotional processing os somatosensory information in chronic pain. Furthermore, our findings suggest that both linear and nonlinear measures of EEG time series may contribute to the understandings of brain dysfunction in chronic pain.Thu, 04 Nov 2010 19:09:10 GMThttp://hdl.handle.net/2117/101292010-11-04T19:09:10ZSitges, Carolina; Bornas, Xavier; Llabrés, Jordi; Noguera Batlle, Miquel; Montoya, PedronoThe aim of our study was to characterize brain dynamics of affective modulation of somatosensory processing in chronic pain. We hypothesized that chronic pain patients will show abnormal EEG activity under negative mood conditions compared to healthly controls. Nineteen patients with chronic pain and 21 healthy subjects participated in the experiment. Multiscale entropy, fractal dimension, event-related potentials, and fast Fourier trasnform were used to analyze EEG data. A significant enhancement of entropy was found in pain patients were viewing unpleasant pictures. By contrast, no signifiant differences due to hemisphere or affective condition were found on nonlinear measures for healthy controls. Analyses of somatosensory ERPs showed that P50 amplitudes elicited by pleasant pictures were more reduced in chronic pain patients than in healthy controls. Finally, we observed that EEG band power was lower in pain patients than in healthy controls, in particular for theta and beata bands over sensorimotor cortices and temporal regions when viewing pleasant images. These findings suggest that sustained pain seems to be accompanied by an abnormal activation and dynamic of brain netwoork related to emotional processing os somatosensory information in chronic pain. Furthermore, our findings suggest that both linear and nonlinear measures of EEG time series may contribute to the understandings of brain dysfunction in chronic pain.On the stability of the Earth's fluctuations spectral peaks at their lowest amplitude level
http://hdl.handle.net/2117/9222
Title: On the stability of the Earth's fluctuations spectral peaks at their lowest amplitude level
Authors: Vila Codina, Josep; Macià Jové, Ramon; Sleeman, Reinold; Correig Blanchar, Antoni MariaThu, 30 Sep 2010 17:38:24 GMThttp://hdl.handle.net/2117/92222010-09-30T17:38:24ZVila Codina, Josep; Macià Jové, Ramon; Sleeman, Reinold; Correig Blanchar, Antoni MarianoMoment tensor inversion for the 5 july 1930 Montilla earthquake (southern Spain)
http://hdl.handle.net/2117/9220
Title: Moment tensor inversion for the 5 july 1930 Montilla earthquake (southern Spain)
Authors: Batlló Ortiz, Josep; Stich, Daniel; Macià Jové, Ramon; Morales Soto, JoseThu, 30 Sep 2010 17:17:55 GMThttp://hdl.handle.net/2117/92202010-09-30T17:17:55ZBatlló Ortiz, Josep; Stich, Daniel; Macià Jové, Ramon; Morales Soto, JosenoOn the dinamics of nonholonomic systems
http://hdl.handle.net/2117/8970
Title: On the dinamics of nonholonomic systems
Authors: Ramírez Inostroza, Rafael Orlando; Sadovskaia Nurimanova, Natalia Guennadievna
Abstract: In the development of nonholonomic mechanics one can observe recurring confusion over
the very equations of motion as well as the deeper questions associated with the geometry
and analysis of these equations. First of all, as far as the equations of motion themselves are concerned, the confusion mainly centered on whether or not the equations could be derived from a variational principle in the usual sense.
Attempting to dissipate this confusion, in the present paper we deduce a new form of
equations of motion which are suitable for both nonholonomic systems with either linear or nonlinear constraints and holonomic systems (A-model). These equations are deduced from the principle of stationary action (or Hamiltonian principle) with nonzero transpositional relations.
We show that the well-known equations of motion for nonholonomic and holonomic systems
can be deduced from the A-model. For the systems which we call the generalized Vorones-Chaplygin systems we deduce the
equations of motion which coincide with the Vorones and Chaplygin equations for the case in which the constraints are linear with respect to the velocity.
An additional result is that the transpositional relations are different from zero only for those generalized coordinates whose variations (in accordance with the equations of nonholonomic constraints) are dependent. For the remaining coordinates, the transpositional relations may be zero.Mon, 20 Sep 2010 12:22:34 GMThttp://hdl.handle.net/2117/89702010-09-20T12:22:34ZRamírez Inostroza, Rafael Orlando; Sadovskaia Nurimanova, Natalia GuennadievnanoIn the development of nonholonomic mechanics one can observe recurring confusion over
the very equations of motion as well as the deeper questions associated with the geometry
and analysis of these equations. First of all, as far as the equations of motion themselves are concerned, the confusion mainly centered on whether or not the equations could be derived from a variational principle in the usual sense.
Attempting to dissipate this confusion, in the present paper we deduce a new form of
equations of motion which are suitable for both nonholonomic systems with either linear or nonlinear constraints and holonomic systems (A-model). These equations are deduced from the principle of stationary action (or Hamiltonian principle) with nonzero transpositional relations.
We show that the well-known equations of motion for nonholonomic and holonomic systems
can be deduced from the A-model. For the systems which we call the generalized Vorones-Chaplygin systems we deduce the
equations of motion which coincide with the Vorones and Chaplygin equations for the case in which the constraints are linear with respect to the velocity.
An additional result is that the transpositional relations are different from zero only for those generalized coordinates whose variations (in accordance with the equations of nonholonomic constraints) are dependent. For the remaining coordinates, the transpositional relations may be zero.