http://hdl.handle.net/2117/3558 Sat, 18 May 2013 15:27:46 GMT 2013-05-18T15:27:46Z webmaster.bupc@upc.edu Universitat Politècnica de Catalunya. Servei de Biblioteques i Documentació no 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 GMT http://hdl.handle.net/2117/18913 2013-04-22T10:46:22Z Grau Sánchez, Miguel; Díaz Barrero, José Luis no 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. 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 GMT http://hdl.handle.net/2117/17510 2013-01-24T13:19:32Z Salvador-Solé, Eduard; Serra, Sinué; Manrique, Alberto; González Casado, Guillermo no 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. 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 GMT http://hdl.handle.net/2117/14731 2012-01-23T10:59:32Z Grau Sánchez, Miguel; González Casado, Guillermo no 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. 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 GMT http://hdl.handle.net/2117/14392 2012-01-02T12:38:30Z Salvador-Solé, Eduard; Serra, Sinué; Manrique, Alberto; González Casado, Guillermo no 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. 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 GMT http://hdl.handle.net/2117/12477 2011-05-05T11:44:52Z Grau Sánchez, Miguel; Díaz Barrero, José Luis no 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. 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 GMT http://hdl.handle.net/2117/12475 2011-05-05T11:25:05Z Grau Sánchez, Miguel; Grau Gotés, Mª Ángela; Díaz Barrero, José Luis no 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. 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, Jose Wed, 06 Apr 2011 09:42:21 GMT http://hdl.handle.net/2117/12274 2011-04-06T09:42:21Z Batlló Ortiz, Josep; Teves-Costa, Paula; Stich, Daniel; Macià Jové, Ramon; Morales Soto, Jose no 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 GMT http://hdl.handle.net/2117/12028 2011-03-23T10:34:46Z Llibre Saló, Jaume; Ramírez Inostroza, Rafael Orlando; Sadovskaia Nurimanova, Natalia Guennadievna no 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. 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 GMT http://hdl.handle.net/2117/12013 2011-03-22T10:51:28Z Grau Gotés, Mª Ángela; Grau Sánchez, Miguel; Montseny Masip, Eduard; Sobrevilla Frisón, Pilar no 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. 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 GMT http://hdl.handle.net/2117/10129 2010-11-04T19:09:10Z Sitges, Carolina; Bornas, Xavier; Llabrés, Jordi; Noguera Batlle, Miquel; Montoya, Pedro no 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. 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 Maria Thu, 30 Sep 2010 17:38:24 GMT http://hdl.handle.net/2117/9222 2010-09-30T17:38:24Z Vila Codina, Josep; Macià Jové, Ramon; Sleeman, Reinold; Correig Blanchar, Antoni Maria no 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, Jose Thu, 30 Sep 2010 17:17:55 GMT http://hdl.handle.net/2117/9220 2010-09-30T17:17:55Z Batlló Ortiz, Josep; Stich, Daniel; Macià Jové, Ramon; Morales Soto, Jose no 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 GMT http://hdl.handle.net/2117/8970 2010-09-20T12:22:34Z Ramírez Inostroza, Rafael Orlando; Sadovskaia Nurimanova, Natalia Guennadievna no 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. http://hdl.handle.net/2117/8969 Title: Cartesian approach for constrained mechanical system with three degree of freedom Authors: Ramírez Inostroza, Rafael Orlando; Sadovskaia Nurimanova, Natalia Guennadievna Abstract: In the history of mechanics, there have been two points of view for studying mechanical systems: The Newtonian and the Cartesian. According the Descartes point of view, the motion of mechanical systems is described by the first-order differential equations in the N dimensional configuration space Q. In this paper we develop the Cartesian approach for mechanical systems with three degrees of freedom and with constraint which are linear with respect to velocity. The obtained results we apply to discuss the integrability of the geodesic flows on the surface in the three dimensional Euclidian space and to analyze the integrability of a heavy rigid body in the Suslov and the Veselov cases. Mon, 20 Sep 2010 11:54:36 GMT http://hdl.handle.net/2117/8969 2010-09-20T11:54:36Z Ramírez Inostroza, Rafael Orlando; Sadovskaia Nurimanova, Natalia Guennadievna no In the history of mechanics, there have been two points of view for studying mechanical systems: The Newtonian and the Cartesian. According the Descartes point of view, the motion of mechanical systems is described by the first-order differential equations in the N dimensional configuration space Q. In this paper we develop the Cartesian approach for mechanical systems with three degrees of freedom and with constraint which are linear with respect to velocity. The obtained results we apply to discuss the integrability of the geodesic flows on the surface in the three dimensional Euclidian space and to analyze the integrability of a heavy rigid body in the Suslov and the Veselov cases. http://hdl.handle.net/2117/8746 Title: On the 16th Hilbert problem for algebraic limit cycles Authors: Llibre Saló, Jaume; Ramírez Inostroza, Rafael Orlando; Sadovskaia Nurimanova, Natalia Guennadievna Abstract: For a polynomial planar vector field of degree n ≥ 2 with generic invariant algebraic curves we show that the maximum number of algebraic limit cycles is 1 + (n − 1)(n − 2)/2 when n is even, and (n − 1)(n − 2)/2 when n is odd. Furthermore, these upper bounds are reached. Fri, 03 Sep 2010 12:50:09 GMT http://hdl.handle.net/2117/8746 2010-09-03T12:50:09Z Llibre Saló, Jaume; Ramírez Inostroza, Rafael Orlando; Sadovskaia Nurimanova, Natalia Guennadievna no For a polynomial planar vector field of degree n ≥ 2 with generic invariant algebraic curves we show that the maximum number of algebraic limit cycles is 1 + (n − 1)(n − 2)/2 when n is even, and (n − 1)(n − 2)/2 when n is odd. Furthermore, these upper bounds are reached.