DSpace Collection:
http://hdl.handle.net/2117/3918
Thu, 23 Oct 2014 14:01:09 GMT2014-10-23T14:01:09Zwebmaster.bupc@upc.eduUniversitat Politècnica de Catalunya. Servei de Biblioteques i DocumentaciónoNonlinear equations for fractional Laplacians, I: Regularity, maximum principles, and Hamiltonian estimates
http://hdl.handle.net/2117/22391
Title: Nonlinear equations for fractional Laplacians, I: Regularity, maximum principles, and Hamiltonian estimates
Authors: Cabré Vilagut, Xavier; Sire, Yannick
Abstract: This is the first of two articles dealing with the equation (-)sv = f (v) in Rn, with s ¿ (0,1), where (-)s stands for the fractional Laplacian — the in¿nitesimal generator of a Lévy process. This equation can be realized as a local linear degenerate elliptic equation in Rn+1+ together with a nonlinear Neumann boundary condition on ¿Rn+1 + =Rn.
In this ¿rst article, we establish necessary conditions on the nonlinearity f to admit certain type of solutions, with special interest in bounded increasing solutions in all of R. These necessary conditions (which will be proven in a follow-up paper to be also suficient for the existence of a bounded increasing solution) are derived from an equality and an estimate involving a Hamiltonian — in the spirit of a result of Modica for the Laplacian. Our proofs are uniform ass ¿1, establishing in the limit the corresponding known results for the Laplacian.
In addition, we study regularity issues, as well as maximum and Harnack principles associated to the equation.http://hdl.handle.net/2117/22391Cabré Vilagut, Xavier; Sire, YannicknoThis is the first of two articles dealing with the equation (-)sv = f (v) in Rn, with s ¿ (0,1), where (-)s stands for the fractional Laplacian — the in¿nitesimal generator of a Lévy process. This equation can be realized as a local linear degenerate elliptic equation in Rn+1+ together with a nonlinear Neumann boundary condition on ¿Rn+1 + =Rn.
In this ¿rst article, we establish necessary conditions on the nonlinearity f to admit certain type of solutions, with special interest in bounded increasing solutions in all of R. These necessary conditions (which will be proven in a follow-up paper to be also suficient for the existence of a bounded increasing solution) are derived from an equality and an estimate involving a Hamiltonian — in the spirit of a result of Modica for the Laplacian. Our proofs are uniform ass ¿1, establishing in the limit the corresponding known results for the Laplacian.
In addition, we study regularity issues, as well as maximum and Harnack principles associated to the equation.J2 effect and elliptic inclined periodic orbits in the collision three-body problem
http://hdl.handle.net/2117/21117
Title: J2 effect and elliptic inclined periodic orbits in the collision three-body problem
Authors: Barrabes, Esther; Cors Iglesias, Josep Maria; Pinyol, Conxita; Soler Villanueva, Jaume
Abstract: The existence of a new class of inclined periodic orbits of the collision restricted
three{body problem is shown. The symmetric periodic solutions found are perturbations of elliptic
kepler orbits and they exist only for special values of the inclination and are related to the motion
of a satellite around an oblate planet.http://hdl.handle.net/2117/21117Barrabes, Esther; Cors Iglesias, Josep Maria; Pinyol, Conxita; Soler Villanueva, Jaumenocollision restricted three-body problem, periodic orbits, symmetric orbits, critical inclination, continuation methodThe existence of a new class of inclined periodic orbits of the collision restricted
three{body problem is shown. The symmetric periodic solutions found are perturbations of elliptic
kepler orbits and they exist only for special values of the inclination and are related to the motion
of a satellite around an oblate planet.A PDE approach of inflammatory phase dynamics in diabetic wounds.
http://hdl.handle.net/2117/24422
Title: A PDE approach of inflammatory phase dynamics in diabetic wounds.
Authors: Consul Porras, M. Nieves; Oliva, Sergio M.; Pellicer, Marta
Abstract: The objective of the present paper is the modeling and analysis of the
dynamics of macrophages and certain growth factors in the in
ammatory phase, the rst one of the wound healing process. It is the phase where there exists a majordi erence between diabetic and non-diabetic wound healing, an e ect that we will
consider in this paper.Mon, 20 Oct 2014 10:27:38 GMThttp://hdl.handle.net/2117/244222014-10-20T10:27:38ZConsul Porras, M. Nieves; Oliva, Sergio M.; Pellicer, MartanoWound healing modelling, diabetes infuence, analytical well-posedness, bifurcation diagrams, numerical analysis of equilibria.The objective of the present paper is the modeling and analysis of the
dynamics of macrophages and certain growth factors in the in
ammatory phase, the rst one of the wound healing process. It is the phase where there exists a majordi erence between diabetic and non-diabetic wound healing, an e ect that we will
consider in this paper.Dynamical sectors for a spinning particle in AdS(3)
http://hdl.handle.net/2117/24386
Title: Dynamical sectors for a spinning particle in AdS(3)
Authors: Batlle Arnau, Carles; Gomis, Jaoquim; Kamimura, kiyoshi; Zanelli, Jorge
Abstract: We consider the dynamics of a particle of mass M and spin J in AdS(3). The study reveals the presence of different dynamical sectors depending on the relative values of M, J and the AdS(3) radius R. For the subcritical (MR2)-R-2 - J(2) > 0 and supercritical (MR2)-R-2 - J(2) < 0 cases, it is seen that the equations of motion give the geodesics of AdS(3). For the critical case (MR2)-R-2 = J(2) there exist extra gauge transformations which further reduce the physical degrees of freedom, and the motion corresponds to the geodesics of AdS(2). This result should be useful in the holographic interpretation of the entanglement entropy for two-dimensional conformal field theories with gravitational anomalies.Thu, 16 Oct 2014 18:06:47 GMThttp://hdl.handle.net/2117/243862014-10-16T18:06:47ZBatlle Arnau, Carles; Gomis, Jaoquim; Kamimura, kiyoshi; Zanelli, JorgenoNEWTON-HOOKE SYMMETRY, NONCOMMUTATIVE PLANE, MECHANICS, GRAVITYWe consider the dynamics of a particle of mass M and spin J in AdS(3). The study reveals the presence of different dynamical sectors depending on the relative values of M, J and the AdS(3) radius R. For the subcritical (MR2)-R-2 - J(2) > 0 and supercritical (MR2)-R-2 - J(2) < 0 cases, it is seen that the equations of motion give the geodesics of AdS(3). For the critical case (MR2)-R-2 = J(2) there exist extra gauge transformations which further reduce the physical degrees of freedom, and the motion corresponds to the geodesics of AdS(2). This result should be useful in the holographic interpretation of the entanglement entropy for two-dimensional conformal field theories with gravitational anomalies.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 ofOn a theory of thermoelastic materials with double porosity structure
http://hdl.handle.net/2117/24346
Title: On a theory of thermoelastic materials with double porosity structure
Authors: Iesan, Dorin; Quintanilla de Latorre, Ramón
Abstract: In this article, we use the Nunziato–Cowin theory of materials with voids to derive a theory of thermoelastic solids, which have a double porosity structure. The new theory is not based on Darcy's law. In the case of equilibrium, in contrast with the classical theory of elastic materials with double porosity, the porosity structure of the body is influenced by the displacement field. We prove the uniqueness of solutions by means of the logarithmic convexity arguments as well as the instability of solutions whenever the internal energy is not positive definite. Later, we use semigroup arguments to prove the existence of solutions in the case that the internal energy is positive. The deformation of an elastic space with a spherical cavity is investigated.
Description: Electronic version of an article published as "Journal of thermal stresses", vol. 37, no 9, 2014, p. 1017-1036. DOI: 10.1080/01495739.2014.914776 <http://www.tandfonline.com/doi/abs/10.1080/01495739.2014.914776#.VDf2nRbQo5h>Fri, 10 Oct 2014 16:05:00 GMThttp://hdl.handle.net/2117/243462014-10-10T16:05:00ZIesan, Dorin; Quintanilla de Latorre, RamónnoExistence and uniqueness results, Instability, Porous thermoelastic solids, Unbounded medium with a cavityIn this article, we use the Nunziato–Cowin theory of materials with voids to derive a theory of thermoelastic solids, which have a double porosity structure. The new theory is not based on Darcy's law. In the case of equilibrium, in contrast with the classical theory of elastic materials with double porosity, the porosity structure of the body is influenced by the displacement field. We prove the uniqueness of solutions by means of the logarithmic convexity arguments as well as the instability of solutions whenever the internal energy is not positive definite. Later, we use semigroup arguments to prove the existence of solutions in the case that the internal energy is positive. The deformation of an elastic space with a spherical cavity is investigated.Distributed parameter model simulation tool for PEM fuel cells
http://hdl.handle.net/2117/24343
Title: Distributed parameter model simulation tool for PEM fuel cells
Authors: Sarmiento Carnevali, María Laura; Serra, Maria; Batlle Arnau, Carles
Abstract: In this work, a simulation tool for proton exchange membrane fuel cells (PEMFC) has been developed, based on a distributed parameter model. The tool is designed to perform studies of time and space variations in the direction of the gas channels. Results for steady-state and dynamic simulations for a single cell of one channel are presented and analyzed. Considered variables are concentrations of reactants, pressures, temperatures, humidification, membrane water content, current density, among others that have significant effects on the performance and durability of PEMFC. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.Fri, 10 Oct 2014 15:43:32 GMThttp://hdl.handle.net/2117/243432014-10-10T15:43:32ZSarmiento Carnevali, María Laura; Serra, Maria; Batlle Arnau, Carlesnopower system control
PARAULES AUTOR: PEMFC, distributed parameter modeling, dynamic simulationIn this work, a simulation tool for proton exchange membrane fuel cells (PEMFC) has been developed, based on a distributed parameter model. The tool is designed to perform studies of time and space variations in the direction of the gas channels. Results for steady-state and dynamic simulations for a single cell of one channel are presented and analyzed. Considered variables are concentrations of reactants, pressures, temperatures, humidification, membrane water content, current density, among others that have significant effects on the performance and durability of PEMFC. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.Static output-feedback controller design for vehicle suspensions: an effective two-step computational approach
http://hdl.handle.net/2117/24326
Title: Static output-feedback controller design for vehicle suspensions: an effective two-step computational approach
Authors: Rubió Massegú, Josep; Palacios Quiñonero, Francisco; Rossell Garriga, Josep Maria; Karimi, Hamid Reza
Abstract: In this study, a novel two-step methodology is applied in designing static output-feedback controllers for a class of vehicle suspension systems. Following this approach, an effective synthesis of static output-feedback controllers can be carried out by solving two consecutive linear matrix inequality optimisation problems. To illustrate the main features of the proposed design strategy, two different static output-feedback H 8 controllers are designed for a quarter-car suspension system. The first of those controllers uses the suspension deflection and the sprung mass velocity as feedback information, whereas the second one only requires the sprung mass velocity to compute the control actions. Numerical simulations indicate that, despite the restricted feedback information, the proposed static output-feedback H 8 controllers exhibit a good behaviour in terms of both frequency and time responses, when compared with the corresponding state-feedback H 8 controller.Thu, 09 Oct 2014 15:14:32 GMThttp://hdl.handle.net/2117/243262014-10-09T15:14:32ZRubió Massegú, Josep; Palacios Quiñonero, Francisco; Rossell Garriga, Josep Maria; Karimi, Hamid RezanoVehicle suspensions, Static output-feedback control, Linear matrix inequalitiesIn this study, a novel two-step methodology is applied in designing static output-feedback controllers for a class of vehicle suspension systems. Following this approach, an effective synthesis of static output-feedback controllers can be carried out by solving two consecutive linear matrix inequality optimisation problems. To illustrate the main features of the proposed design strategy, two different static output-feedback H 8 controllers are designed for a quarter-car suspension system. The first of those controllers uses the suspension deflection and the sprung mass velocity as feedback information, whereas the second one only requires the sprung mass velocity to compute the control actions. Numerical simulations indicate that, despite the restricted feedback information, the proposed static output-feedback H 8 controllers exhibit a good behaviour in terms of both frequency and time responses, when compared with the corresponding state-feedback H 8 controller.A modified Chua chaotic oscillator and its application to secure communications
http://hdl.handle.net/2117/24318
Title: A modified Chua chaotic oscillator and its application to secure communications
Authors: Zapateiro, Mauricio; Acho Zuppa, Leonardo; Vidal Seguí, Yolanda
Abstract: In this paper, a new modified Chua oscillator is introduced. The original Chua oscillator is well known for its simple implementation and mathemati- cal modeling. A modification of the oscillator is proposed in order to facilitate the synchronization and the encryption and decryption scheme. The modifi- cation consists in changing the nonlinear term of the original oscillator to a smooth and bounded nonlinear function. A bifurcation diagram, a Poincar ´e map and the Lyapunov exponents are presented as proofs of chaoticity of the newly modified oscillator. An application to secure communications is pro- posed in which two channels are used. Numerical simulations are performed in order to analyze the communication system.Thu, 09 Oct 2014 12:51:28 GMThttp://hdl.handle.net/2117/243182014-10-09T12:51:28ZZapateiro, Mauricio; Acho Zuppa, Leonardo; Vidal Seguí, YolandanoChua oscillator, chaos, secure communication, synchronization, Lyapunov methodsIn this paper, a new modified Chua oscillator is introduced. The original Chua oscillator is well known for its simple implementation and mathemati- cal modeling. A modification of the oscillator is proposed in order to facilitate the synchronization and the encryption and decryption scheme. The modifi- cation consists in changing the nonlinear term of the original oscillator to a smooth and bounded nonlinear function. A bifurcation diagram, a Poincar ´e map and the Lyapunov exponents are presented as proofs of chaoticity of the newly modified oscillator. An application to secure communications is pro- posed in which two channels are used. Numerical simulations are performed in order to analyze the communication system.Damage detection in composite materials structures under variable loads conditions by using fiber Bragg gratings and principal component analysis, involving new unfolding and scaling methods
http://hdl.handle.net/2117/24286
Title: Damage detection in composite materials structures under variable loads conditions by using fiber Bragg gratings and principal component analysis, involving new unfolding and scaling methods
Authors: Sierra Pérez, Julian; Guemes, Alfredo; Mujica Delgado, Luis Eduardo; Ruiz Ordóñez, Magda
Abstract: An innovative methodology based on the use of fiber Bragg gratings as strain sensors and strain field pattern recognition is proposed for damage detection in composite materials structures. The strain field pattern recognition technique is based on principal component analysis. Damage indices (T 2 and Q) and detection thresholds are presented. New techniques for unfolding and scaling tridimensional matrices arrays obtained from structures working under variable load conditions are presented.Mon, 06 Oct 2014 12:34:00 GMThttp://hdl.handle.net/2117/242862014-10-06T12:34:00ZSierra Pérez, Julian; Guemes, Alfredo; Mujica Delgado, Luis Eduardo; Ruiz Ordóñez, MagdanoAn innovative methodology based on the use of fiber Bragg gratings as strain sensors and strain field pattern recognition is proposed for damage detection in composite materials structures. The strain field pattern recognition technique is based on principal component analysis. Damage indices (T 2 and Q) and detection thresholds are presented. New techniques for unfolding and scaling tridimensional matrices arrays obtained from structures working under variable load conditions are presented.Power indices of influence games and new centrality measures for agent societies and social networks
http://hdl.handle.net/2117/24245
Title: Power indices of influence games and new centrality measures for agent societies and social networks
Authors: Molinero Albareda, Xavier; Riquelme Csori, Fabián; Serna Iglesias, María José
Abstract: We propose as centrality measures for social networks two classical power indices, Banzhaf and Shapley-Shubik, and two new measures, effort and satisfaction, related to the spread of influence process that emerge from the subjacent influence game. We perform a comparison of these measures with three well known centrality measures, degree, closeness and betweenness, applied to three simple social networks.Fri, 03 Oct 2014 13:58:17 GMThttp://hdl.handle.net/2117/242452014-10-03T13:58:17ZMolinero Albareda, Xavier; Riquelme Csori, Fabián; Serna Iglesias, María JosénoSocial network, Centrality, Power index, Influence game, Simple gameWe propose as centrality measures for social networks two classical power indices, Banzhaf and Shapley-Shubik, and two new measures, effort and satisfaction, related to the spread of influence process that emerge from the subjacent influence game. We perform a comparison of these measures with three well known centrality measures, degree, closeness and betweenness, applied to three simple social networks.Whitehead problems for words in $\ZZ^m \times F_n$
http://hdl.handle.net/2117/24243
Title: Whitehead problems for words in $\ZZ^m \times F_n$
Authors: Delgado Rodríguez, Jordi
Abstract: We solve the Whitehead problem for automorphisms, monomorphisms and endomorphisms in Zm Fn after giving an explicit description of each of these families of transformations.Fri, 03 Oct 2014 13:38:32 GMThttp://hdl.handle.net/2117/242432014-10-03T13:38:32ZDelgado Rodríguez, JordinoWe solve the Whitehead problem for automorphisms, monomorphisms and endomorphisms in Zm Fn after giving an explicit description of each of these families of transformations.Quantum Google in a complex network
http://hdl.handle.net/2117/24220
Title: Quantum Google in a complex network
Authors: Paparo, Giuseppe Davide; Muller, Markus; Comellas Padró, Francesc de Paula; Martin Delgado, Miguel Angel
Abstract: We investigate the behaviour of the recently proposed Quantum PageRank algorithm, in large complex networks. We find that the algorithm is able to univocally reveal the underlying topology of the network and to identify and order the most relevant nodes. Furthermore, it is capable to clearly highlight the structure of secondary hubs and to resolve the degeneracy in importance of the low lying part of the list of rankings. The quantum algorithm displays an increased stability with respect to a variation of the damping parameter, present in the Google algorithm, and a more clearly pronounced power-law behaviour in the distribution of importance, as compared to the classical algorithm. We test the performance and confirm the listed features by applying it to real world examples from the WWW. Finally, we raise and partially address whether the increased sensitivity of the quantum algorithm persists under coordinated attacks in scale-free and random networks.Thu, 02 Oct 2014 17:35:16 GMThttp://hdl.handle.net/2117/242202014-10-02T17:35:16ZPaparo, Giuseppe Davide; Muller, Markus; Comellas Padró, Francesc de Paula; Martin Delgado, Miguel AngelnoComputer science, Information technology, Information theory and computation, Quantum information, Complex networksWe investigate the behaviour of the recently proposed Quantum PageRank algorithm, in large complex networks. We find that the algorithm is able to univocally reveal the underlying topology of the network and to identify and order the most relevant nodes. Furthermore, it is capable to clearly highlight the structure of secondary hubs and to resolve the degeneracy in importance of the low lying part of the list of rankings. The quantum algorithm displays an increased stability with respect to a variation of the damping parameter, present in the Google algorithm, and a more clearly pronounced power-law behaviour in the distribution of importance, as compared to the classical algorithm. We test the performance and confirm the listed features by applying it to real world examples from the WWW. Finally, we raise and partially address whether the increased sensitivity of the quantum algorithm persists under coordinated attacks in scale-free and random networks.A connection between discrete individual-based and continuous population-based models: A forest modelling case study
http://hdl.handle.net/2117/24214
Title: A connection between discrete individual-based and continuous population-based models: A forest modelling case study
Authors: Gómez Mourelo, Pablo; Ginovart Gisbert, Marta
Abstract: Modelling is perceived as a way of dealing with real life activities. The aim of this work is to compare two approaches to
study forest dynamics, namely discrete individual-based and continuous population-based models, in order to contribute to
an improvement in their use among researchers. An analysis of the strengths, weaknesses, opportunities and threats of the
two different approaches, jointly with a mention of the state-of-the-art, allows us to illustrate this discussion. We will also
provide a bridge or connection between these two modelling methodologies. This link will be developed in detail in a
particular study case. Firstly, an individual-tree based model to deal with dynamics of forests is presented. Secondly, this
model is scaled up to a system of partial differential equations, which represents the limiting behaviour of the individualbased
model.Thu, 02 Oct 2014 17:02:29 GMThttp://hdl.handle.net/2117/242142014-10-02T17:02:29ZGómez Mourelo, Pablo; Ginovart Gisbert, MartanoIndividual-based model, Population-based model, Discrete versus continuous model, Forest dynamics, Tree populationModelling is perceived as a way of dealing with real life activities. The aim of this work is to compare two approaches to
study forest dynamics, namely discrete individual-based and continuous population-based models, in order to contribute to
an improvement in their use among researchers. An analysis of the strengths, weaknesses, opportunities and threats of the
two different approaches, jointly with a mention of the state-of-the-art, allows us to illustrate this discussion. We will also
provide a bridge or connection between these two modelling methodologies. This link will be developed in detail in a
particular study case. Firstly, an individual-tree based model to deal with dynamics of forests is presented. Secondly, this
model is scaled up to a system of partial differential equations, which represents the limiting behaviour of the individualbased
model.On a-roughly weighted games
http://hdl.handle.net/2117/24210
Title: On a-roughly weighted games
Authors: Freixas Bosch, Josep; Kurz, Sascha
Abstract: Gvozdeva, Hemaspaandra, and Slinko (2011) have introduced three hierarchies for simple games in order to measure the distance of a given simple game to the class of (roughly) weighted voting games. Their third class C-alpha consists of all simple games permitting a weighted representation such that each winning coalition has a weight of at least and each losing coalition a weight of at most alpha. For a given game the minimal possible value of alpha is called its critical threshold value. We continue the work on the critical threshold value, initiated by Gvozdeva et al., and contribute some new results on the possible values for a given number of voters as well as some general bounds for restricted subclasses of games. A strong relation between this concept and the cost of stability, i.e. the minimum amount of external payment to ensure stability in a coalitional game, is uncovered.Thu, 02 Oct 2014 16:20:55 GMThttp://hdl.handle.net/2117/242102014-10-02T16:20:55ZFreixas Bosch, Josep; Kurz, SaschanoSimple game, Weighted game, Complete simple game, Roughly weighted game, Voting theory, HierarchyGvozdeva, Hemaspaandra, and Slinko (2011) have introduced three hierarchies for simple games in order to measure the distance of a given simple game to the class of (roughly) weighted voting games. Their third class C-alpha consists of all simple games permitting a weighted representation such that each winning coalition has a weight of at least and each losing coalition a weight of at most alpha. For a given game the minimal possible value of alpha is called its critical threshold value. We continue the work on the critical threshold value, initiated by Gvozdeva et al., and contribute some new results on the possible values for a given number of voters as well as some general bounds for restricted subclasses of games. A strong relation between this concept and the cost of stability, i.e. the minimum amount of external payment to ensure stability in a coalitional game, is uncovered.