DSpace Collection:
http://hdl.handle.net/2117/3918
Sun, 24 May 2015 07:51:00 GMT2015-05-24T07:51:00Zwebmaster.bupc@upc.eduUniversitat Politècnica de Catalunya. Servei de Biblioteques i DocumentaciónoJ2 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.Nonlinear 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.Static output-feedback control for vehicle suspensions: a single-step linear matrix inequality approach
http://hdl.handle.net/2117/28020
Title: Static output-feedback control for vehicle suspensions: a single-step linear matrix inequality approach
Authors: Rubió Massegú, Josep; Palacios Quiñonero, Francisco; Rossell Garriga, Josep Maria; Karimi, Hamid Reza
Abstract: In this paper, a new strategy to design static output-feedback controllers for a class of vehicle suspension systems is presented. A theoretical background on recent advances in output-feedback control is first provided, which makes possible an effective synthesis of static output-feedback controllers by solving a single linear matrix inequality optimization problem. Next, a simplified model of a quarter-car suspension system is proposed, taking the ride comfort, suspension stroke, road holding ability, and control effort as the main performance criteria in the vehicle suspension design. The new approach is then used to design a static output-feedback controller that only uses the suspension deflection and the sprung mass velocity as feedback information. Numerical simulations indicate that, despite the restricted feedback information, this static output-feedback controller exhibits an excellent behavior in terms of both frequency and time responses, when compared with the corresponding state-feedback controller.Fri, 22 May 2015 15:49:52 GMThttp://hdl.handle.net/2117/280202015-05-22T15:49:52ZRubió Massegú, Josep; Palacios Quiñonero, Francisco; Rossell Garriga, Josep Maria; Karimi, Hamid RezanoIn this paper, a new strategy to design static output-feedback controllers for a class of vehicle suspension systems is presented. A theoretical background on recent advances in output-feedback control is first provided, which makes possible an effective synthesis of static output-feedback controllers by solving a single linear matrix inequality optimization problem. Next, a simplified model of a quarter-car suspension system is proposed, taking the ride comfort, suspension stroke, road holding ability, and control effort as the main performance criteria in the vehicle suspension design. The new approach is then used to design a static output-feedback controller that only uses the suspension deflection and the sprung mass velocity as feedback information. Numerical simulations indicate that, despite the restricted feedback information, this static output-feedback controller exhibits an excellent behavior in terms of both frequency and time responses, when compared with the corresponding state-feedback controller.Bifurcation of relative equilibria of the (1+3)-body problem
http://hdl.handle.net/2117/28007
Title: Bifurcation of relative equilibria of the (1+3)-body problem
Authors: Corbera, M.; Cors Iglesias, Josep Maria; Llibre Saló, Jaume; Moeckel, Richard
Abstract: We study the relative equilibria of the limit case of the planar Newtonian 4-body problem when three masses tend to zero, the so-called (1+3)-body problem. Depending on the values of the infinitesimal masses the number of relative equilibria varies from ten to fourteen. Always six of these relative equilibria are convex and the others are concave. Each convex relative equilibrium of the (1+3)-body problem can be continued to a unique family of relative equilibria of the general 4-body problem when three of the masses are sufficiently small and every convex relative equilibrium for these masses belongs to one of these six families.Thu, 21 May 2015 15:13:18 GMThttp://hdl.handle.net/2117/280072015-05-21T15:13:18ZCorbera, M.; Cors Iglesias, Josep Maria; Llibre Saló, Jaume; Moeckel, RichardnoCelestial mechanics, Relative equilibria, (1+n)-body problemWe study the relative equilibria of the limit case of the planar Newtonian 4-body problem when three masses tend to zero, the so-called (1+3)-body problem. Depending on the values of the infinitesimal masses the number of relative equilibria varies from ten to fourteen. Always six of these relative equilibria are convex and the others are concave. Each convex relative equilibrium of the (1+3)-body problem can be continued to a unique family of relative equilibria of the general 4-body problem when three of the masses are sufficiently small and every convex relative equilibrium for these masses belongs to one of these six families.Phase-field modeling and simulation of fracture in brittle materials with strongly anisotropic surface energy
http://hdl.handle.net/2117/28004
Title: Phase-field modeling and simulation of fracture in brittle materials with strongly anisotropic surface energy
Authors: Li, Bin; Peco, Christian; Millán, Daniel; Arias Vicente, Irene; Arroyo Balaguer, Marino
Abstract: Crack propagation in brittle materials with anisotropic surface energy is important in applications involving single crystals, extruded polymers, or geological and organic materials. Furthermore, when this anisotropy is strong, the phenomenology of crack propagation becomes very rich, with forbidden crack propagation directions or complex sawtooth crack patterns. This problem interrogates fundamental issues in fracture mechanics, including the principles behind the selection of crack direction. Here, we propose a variational phase-field model for strongly anisotropic fracture, which resorts to the extended Cahn-Hilliard framework proposed in the context of crystal growth. Previous phase-field models for anisotropic fracture were formulated in a framework only allowing for weak anisotropy. We implement numerically our higher-order phase-field model with smooth local maximum entropy approximants in a direct Galerkin method. The numerical results exhibit all the features of strongly anisotropic fracture and reproduce strikingly well recent experimental observations.Thu, 21 May 2015 12:33:42 GMThttp://hdl.handle.net/2117/280042015-05-21T12:33:42ZLi, Bin; Peco, Christian; Millán, Daniel; Arias Vicente, Irene; Arroyo Balaguer, Marinonofracture, meshfree methods, phase-field models, strongly anisotropic surface energy, local maximum entropy approximantsCrack propagation in brittle materials with anisotropic surface energy is important in applications involving single crystals, extruded polymers, or geological and organic materials. Furthermore, when this anisotropy is strong, the phenomenology of crack propagation becomes very rich, with forbidden crack propagation directions or complex sawtooth crack patterns. This problem interrogates fundamental issues in fracture mechanics, including the principles behind the selection of crack direction. Here, we propose a variational phase-field model for strongly anisotropic fracture, which resorts to the extended Cahn-Hilliard framework proposed in the context of crystal growth. Previous phase-field models for anisotropic fracture were formulated in a framework only allowing for weak anisotropy. We implement numerically our higher-order phase-field model with smooth local maximum entropy approximants in a direct Galerkin method. The numerical results exhibit all the features of strongly anisotropic fracture and reproduce strikingly well recent experimental observations.Phase-field modeling of fracture in ferroelectric materials
http://hdl.handle.net/2117/28003
Title: Phase-field modeling of fracture in ferroelectric materials
Authors: Abdollahi Hosnijeh, Amir; Arias Vicente, Irene
Abstract: This paper presents a family of phase-field models for the coupled simulation of the microstructure formation and evolution, and the nucleation and propagation of cracks in single and polycrystalline ferroelectric materials. The first objective is to introduce a phase-field model for ferroelectric single crystals. The model naturally couples two existing energetic phase-field approaches for brittle fracture and ferroelectric domain formation and evolution. Simulations show the interactions between the microstructure and the crack under mechanical and electromechanical loadings. Another objective of this paper is to encode different crack face boundary conditions into the phase-field framework since these conditions strongly affect the fracture behavior of ferroelectrics. The smeared imposition of these conditions are discussed and the results are compared with that of sharp crack models to validate the proposed approaches. Simulations show the effects of different conditions and electromechanical loadings on the crack propagation. In a third step, the model is modified by introducing a crack non-interpenetration condition in the variational approach to fracture accounting for the asymmetric behavior in tension and compression. The modified model makes it possible to explain anisotropic crack growth in ferroelectrics under the Vickers indentation loading. This model is also employed for the fracture analysis of multilayer ferroelectric actuators, which shows the potential of the model for future applications. The coupled phase-field model is also extended to polycrystals by introducing realistic polycrystalline microstructures in the model. Inter- and trans-granular crack propagation modes are observed in the simulations. Finally, and for completeness, the phase-field theory is extended to the simulation of the propagation of conducting cracks under purely electrical loading and to the three-dimensional simulation of crack propagation in ferroelectric single crystals. Salient features of the crack propagation phenomenon predicted by the simulations of this paper are directly compared with experimental observations.Thu, 21 May 2015 12:12:44 GMThttp://hdl.handle.net/2117/280032015-05-21T12:12:44ZAbdollahi Hosnijeh, Amir; Arias Vicente, IrenenoFerroelectricity, Piezoelectricity, Fracture, Phase-field models, Polycrystals, Finite element analysis, Domain switchingThis paper presents a family of phase-field models for the coupled simulation of the microstructure formation and evolution, and the nucleation and propagation of cracks in single and polycrystalline ferroelectric materials. The first objective is to introduce a phase-field model for ferroelectric single crystals. The model naturally couples two existing energetic phase-field approaches for brittle fracture and ferroelectric domain formation and evolution. Simulations show the interactions between the microstructure and the crack under mechanical and electromechanical loadings. Another objective of this paper is to encode different crack face boundary conditions into the phase-field framework since these conditions strongly affect the fracture behavior of ferroelectrics. The smeared imposition of these conditions are discussed and the results are compared with that of sharp crack models to validate the proposed approaches. Simulations show the effects of different conditions and electromechanical loadings on the crack propagation. In a third step, the model is modified by introducing a crack non-interpenetration condition in the variational approach to fracture accounting for the asymmetric behavior in tension and compression. The modified model makes it possible to explain anisotropic crack growth in ferroelectrics under the Vickers indentation loading. This model is also employed for the fracture analysis of multilayer ferroelectric actuators, which shows the potential of the model for future applications. The coupled phase-field model is also extended to polycrystals by introducing realistic polycrystalline microstructures in the model. Inter- and trans-granular crack propagation modes are observed in the simulations. Finally, and for completeness, the phase-field theory is extended to the simulation of the propagation of conducting cracks under purely electrical loading and to the three-dimensional simulation of crack propagation in ferroelectric single crystals. Salient features of the crack propagation phenomenon predicted by the simulations of this paper are directly compared with experimental observations.Comparison of the microbial dynamics and biochemistry of laboratory sourdoughs prepared with grape, apple and yogurt
http://hdl.handle.net/2117/27975
Title: Comparison of the microbial dynamics and biochemistry of laboratory sourdoughs prepared with grape, apple and yogurt
Authors: Gordún Quiles, Elena; Valle Mendoza, Luis Javier del; Ginovart Gisbert, Marta; Carbó Moliner, Rosa
Abstract: The microbiological culture-dependent characterization and physicochemical characteristics of laboratory sourdough prepared with grape (GS) were evaluated and compared with apple (AS) and yogurt (YS), which are the usual Spanish sourdough ingredients. Ripe GS took longer than AS and YS to reach the appropriate acidity and achieved lower values of lactic acidWed, 20 May 2015 10:22:58 GMThttp://hdl.handle.net/2117/279752015-05-20T10:22:58ZGordún Quiles, Elena; Valle Mendoza, Luis Javier del; Ginovart Gisbert, Marta; Carbó Moliner, RosanoSourdough, grape, ingredients, lactic acid bacteria, yeastThe microbiological culture-dependent characterization and physicochemical characteristics of laboratory sourdough prepared with grape (GS) were evaluated and compared with apple (AS) and yogurt (YS), which are the usual Spanish sourdough ingredients. Ripe GS took longer than AS and YS to reach the appropriate acidity and achieved lower values of lactic acidThe proportional partitional Shapley value
http://hdl.handle.net/2117/27972
Title: The proportional partitional Shapley value
Authors: Alonso Meijide, José María; Carreras Escobar, Francisco; Costa Bouzas, Julián; García Jurado, Ignacio
Abstract: A new coalitional value is proposed under the hypothesis of isolated unions. The main
difference between this value and the Aumann–Drèze value is that the allocations within
each union are not given by the Shapley value of the restricted game but proportionally
to the Shapley value of the original game. Axiomatic characterizations of the new value,
examples illustrating its application and a comparative discussion are provided.Tue, 19 May 2015 17:50:13 GMThttp://hdl.handle.net/2117/279722015-05-19T17:50:13ZAlonso Meijide, José María; Carreras Escobar, Francisco; Costa Bouzas, Julián; García Jurado, IgnacionoGame theory, (TU) cooperative game, Shapley value, Coalition structure, Aumann–Drèze valueA new coalitional value is proposed under the hypothesis of isolated unions. The main
difference between this value and the Aumann–Drèze value is that the allocations within
each union are not given by the Shapley value of the restricted game but proportionally
to the Shapley value of the original game. Axiomatic characterizations of the new value,
examples illustrating its application and a comparative discussion are provided.Empty non-convex and convex four-gons in random point sets
http://hdl.handle.net/2117/27964
Title: Empty non-convex and convex four-gons in random point sets
Authors: Fabila Monroy, Ruy; Huemer, Clemens; Mitsche, Dieter
Abstract: Let S be a set of n points distributed uniformly and independently in a convex, bounded set in the plane. A four-gon is called empty if it contains no points of S in its interior. We show that the expected number of empty non-convex four-gons with vertices from S is 12 n(2) log n + o(n(2) log n) and the expected number of empty convex four-gons with vertices from S is Theta(n(2)).Tue, 19 May 2015 11:34:59 GMThttp://hdl.handle.net/2117/279642015-05-19T11:34:59ZFabila Monroy, Ruy; Huemer, Clemens; Mitsche, Dieternorandom point set, empty four-gon, polygon, geometric probability, N-RANDOM POINTS, PROBABILITY, TRIANGLES, POSITION, POLYGONS, NUMBER, HOLESLet S be a set of n points distributed uniformly and independently in a convex, bounded set in the plane. A four-gon is called empty if it contains no points of S in its interior. We show that the expected number of empty non-convex four-gons with vertices from S is 12 n(2) log n + o(n(2) log n) and the expected number of empty convex four-gons with vertices from S is Theta(n(2)).Geometric classification of monogenic subspaces and uniparametric linear control systems
http://hdl.handle.net/2117/27960
Title: Geometric classification of monogenic subspaces and uniparametric linear control systems
Authors: Compta Creus, Albert; Ferrer Llop, Josep
Abstract: We present a geometric approach to the classification of monogenic invariant subspaces, alternative to the classical algebraic one, which allows us to obtain several matricial canonical forms for each class. Some applications are derived: canonical coordinates of a vector with regard to an endomorphism, and a canonical form for uniparametric linear control systems, not necessarily controllable, with regard to linear changes of state variables. Moreover, the pointwise construction
can be extended to differentiable families of changes of basis when differentiable families of equivalent monogenic subspaces are considered.Tue, 19 May 2015 08:05:40 GMThttp://hdl.handle.net/2117/279602015-05-19T08:05:40ZCompta Creus, Albert; Ferrer Llop, Josepnoendomorphism, invariant subspaces, monogenic subspaces, marked
matrices, uniparametric control system, bimodal dynamical systemWe present a geometric approach to the classification of monogenic invariant subspaces, alternative to the classical algebraic one, which allows us to obtain several matricial canonical forms for each class. Some applications are derived: canonical coordinates of a vector with regard to an endomorphism, and a canonical form for uniparametric linear control systems, not necessarily controllable, with regard to linear changes of state variables. Moreover, the pointwise construction
can be extended to differentiable families of changes of basis when differentiable families of equivalent monogenic subspaces are considered.Oxidative stress is a central target for physical exercise neuroprotection against pathological brain aging
http://hdl.handle.net/2117/27948
Title: Oxidative stress is a central target for physical exercise neuroprotection against pathological brain aging
Authors: Garcia-Mesa, Yoelvis; Colie, Sandra; Corpas, Ruben; Cristofol, Rosa; Comellas Padró, Francesc de Paula; Nebreda, Angel; Giménez-Llort, Lydia; Sanfeliu, Coral
Abstract: Physical exercise is suggested for preventing or delaying senescence and Alzheimer’s disease (AD). We have examined its therapeutic value in the advanced stage of AD-like pathology in 3xTg-AD female mice through voluntary wheel running from 12 to 15 months of age. Mice submitted to exercise showed improved body fitness, immunorejuvenation, improvement of behavior and cognition, and reduced amyloid and tau pathology. Brain tissue analysis of aged 3xTg-AD mice showed high levels of oxidative damage. However, this damage was decreased by physical exercise through regulation of redox homeostasis. Network analyses showed that oxidative stress was a central event, which correlated with AD-like pathology and the AD-related behaviors of anxiety, apathy, and cognitive loss. This study corroborates the importance of redox mechanisms in the neuroprotective effect of physical exercise, and supports the theory of the crucial role of oxidative stress in the switch from normal brain aging to pathological aging and AD.Mon, 18 May 2015 12:01:12 GMThttp://hdl.handle.net/2117/279482015-05-18T12:01:12ZGarcia-Mesa, Yoelvis; Colie, Sandra; Corpas, Ruben; Cristofol, Rosa; Comellas Padró, Francesc de Paula; Nebreda, Angel; Giménez-Llort, Lydia; Sanfeliu, CoralnoAlzheimer’s disease, 3xTg-AD mice, Physical exercise, Oxidative stress, Behavior tests, Cognition, Amyloid ßPhospho-tauPhysical exercise is suggested for preventing or delaying senescence and Alzheimer’s disease (AD). We have examined its therapeutic value in the advanced stage of AD-like pathology in 3xTg-AD female mice through voluntary wheel running from 12 to 15 months of age. Mice submitted to exercise showed improved body fitness, immunorejuvenation, improvement of behavior and cognition, and reduced amyloid and tau pathology. Brain tissue analysis of aged 3xTg-AD mice showed high levels of oxidative damage. However, this damage was decreased by physical exercise through regulation of redox homeostasis. Network analyses showed that oxidative stress was a central event, which correlated with AD-like pathology and the AD-related behaviors of anxiety, apathy, and cognitive loss. This study corroborates the importance of redox mechanisms in the neuroprotective effect of physical exercise, and supports the theory of the crucial role of oxidative stress in the switch from normal brain aging to pathological aging and AD.A medial-axis-based model for propagating cracks in a regularised bulk
http://hdl.handle.net/2117/27935
Title: A medial-axis-based model for propagating cracks in a regularised bulk
Authors: Tamayo Mas, Elena; Rodríguez Ferran, Antonio
Abstract: A new continuous-discontinuous strategy for the simulation of failure is presented. The continuous bulk is regularised by means of a gradient-enhanced damage model, where non-locality is introduced at the level of displacements. As soon as the damage parameter is close or equal to 1, a traction-free crack is introduced. To determine the direction of crack growth, a new criterion is proposed. In contrast to traditional techniques, where mechanical criteria are used to define the crack path, here, a geometrical approach is used. More specifically, given a regularised damage field D(x), we propose to propagate the discontinuity following the direction dictated by the medial axis of the isoline (or isosurface in 3D) D(x) = D*. The proposed approach is tested on different two-dimensional and three-dimensional examples that illustrate that this combined methodology is able to deal with damage growth and material separation. Copyright (c) 2014 John Wiley & Sons, Ltd.Fri, 15 May 2015 11:31:56 GMThttp://hdl.handle.net/2117/279352015-05-15T11:31:56ZTamayo Mas, Elena; Rodríguez Ferran, Antonionocontinuous-discontinuous strategy, regularisation, smoothed displacements, propagating cracks, medial axis, NONLOCAL DAMAGE MODEL, FINITE-ELEMENT-METHOD, GRADIENT ELASTICITY, BOUNDARY-CONDITIONS, CONTINUUM DAMAGE, FAILURE, FRACTURE, GROWTH, DISPLACEMENTS, FORMULATIONA new continuous-discontinuous strategy for the simulation of failure is presented. The continuous bulk is regularised by means of a gradient-enhanced damage model, where non-locality is introduced at the level of displacements. As soon as the damage parameter is close or equal to 1, a traction-free crack is introduced. To determine the direction of crack growth, a new criterion is proposed. In contrast to traditional techniques, where mechanical criteria are used to define the crack path, here, a geometrical approach is used. More specifically, given a regularised damage field D(x), we propose to propagate the discontinuity following the direction dictated by the medial axis of the isoline (or isosurface in 3D) D(x) = D*. The proposed approach is tested on different two-dimensional and three-dimensional examples that illustrate that this combined methodology is able to deal with damage growth and material separation. Copyright (c) 2014 John Wiley & Sons, Ltd.A new application of the $\otimes_h$-product to $\alpha$-labelings
http://hdl.handle.net/2117/27897
Title: A new application of the $\otimes_h$-product to $\alpha$-labelings
Authors: López Masip, Susana Clara; Muntaner Batle, Francesc Antoni
Abstract: The weak tensor product was introduced by Snevily as a way to construct new graphs that admit a-labelings from a pair of known a-graphs. In this article, we show that this product and the application to a-labelings can be generalized by considering as a second factor of the product, a family G of bipartite (p, q)-graphs, p and q fixed. The only additional restriction that we should consider is that for every F ¿ G , there exists an a-labeling fF with fF (V(F )) = L¿H, where L, H ¿ [0, q] are the stable sets induced by the characteristic of fF and they do not depend on F .Wealso obtain analogous applications to near a-labelings and bigraceful labelings.Tue, 12 May 2015 11:53:58 GMThttp://hdl.handle.net/2117/278972015-05-12T11:53:58ZLópez Masip, Susana Clara; Muntaner Batle, Francesc AntoninoWeak tensor product, ¿h-product, a-labeling, Near a-labeling, Bigraceful labeling, DecompositionThe weak tensor product was introduced by Snevily as a way to construct new graphs that admit a-labelings from a pair of known a-graphs. In this article, we show that this product and the application to a-labelings can be generalized by considering as a second factor of the product, a family G of bipartite (p, q)-graphs, p and q fixed. The only additional restriction that we should consider is that for every F ¿ G , there exists an a-labeling fF with fF (V(F )) = L¿H, where L, H ¿ [0, q] are the stable sets induced by the characteristic of fF and they do not depend on F .Wealso obtain analogous applications to near a-labelings and bigraceful labelings.A Worldwide ionospheric model for fast precise point positioning
http://hdl.handle.net/2117/27895
Title: A Worldwide ionospheric model for fast precise point positioning
Authors: Rovira Garcia, Adrià; Juan Zornoza, José Miguel; Sanz Subirana, Jaume; González Casado, Guillermo
Abstract: Fast precise point positioning (Fast-PPP) is a satellite-based navigation technique using an accurate real-time ionospheric modeling to achieve high accuracy quickly. In this paper, an end-to-end performance assessment of Fast-PPP is presented in near-maximum Solar Cycle conditions; from the accuracy of the Central Processing Facility corrections, to the user positioning. A planetary distribution of permanent receivers including challenging conditions at equatorial latitudes, is navigated in pure kinematic mode, located from 100 to 1300 km away from the nearest reference station used to derive the ionospheric model.
It is shown that satellite orbits and clocks accurate to few centimeters
and few tenths of nanoseconds, used in conjunction with an ionosphere with an accuracy better than 1 Total Electron Content Unit (16 cm in L1) reduce the convergence time of dual-frequency Precise Point Positioning, to decimeter-level (3-D) solutions. Horizontal convergence times are shortened 40% to 90%, whereas the vertical components are reduced by 20% to 60%. A metric to evaluate the quality of any ionospheric model for Global Navigation Satellite System is also proposed. The ionospheric modeling accuracy is directly translated to mass-market single-frequency
users. The 95th percentile of horizontal and vertical accuracies is shown to be 40 and 60 cm for single-frequency users and 9 and 16 cm for dual-frequency users. The tradeoff between the formal and actual positioning errors has been carefully studied to set realistic confidence levels to the corrections.Tue, 12 May 2015 11:44:15 GMThttp://hdl.handle.net/2117/278952015-05-12T11:44:15ZRovira Garcia, Adrià; Juan Zornoza, José Miguel; Sanz Subirana, Jaume; González Casado, GuillermonoGlobal Navigation Satellite System (GNSS), precise point positioning (PPP), real-time ionospheric corrections, undifferenced ambiguity fixing.Fast precise point positioning (Fast-PPP) is a satellite-based navigation technique using an accurate real-time ionospheric modeling to achieve high accuracy quickly. In this paper, an end-to-end performance assessment of Fast-PPP is presented in near-maximum Solar Cycle conditions; from the accuracy of the Central Processing Facility corrections, to the user positioning. A planetary distribution of permanent receivers including challenging conditions at equatorial latitudes, is navigated in pure kinematic mode, located from 100 to 1300 km away from the nearest reference station used to derive the ionospheric model.
It is shown that satellite orbits and clocks accurate to few centimeters
and few tenths of nanoseconds, used in conjunction with an ionosphere with an accuracy better than 1 Total Electron Content Unit (16 cm in L1) reduce the convergence time of dual-frequency Precise Point Positioning, to decimeter-level (3-D) solutions. Horizontal convergence times are shortened 40% to 90%, whereas the vertical components are reduced by 20% to 60%. A metric to evaluate the quality of any ionospheric model for Global Navigation Satellite System is also proposed. The ionospheric modeling accuracy is directly translated to mass-market single-frequency
users. The 95th percentile of horizontal and vertical accuracies is shown to be 40 and 60 cm for single-frequency users and 9 and 16 cm for dual-frequency users. The tradeoff between the formal and actual positioning errors has been carefully studied to set realistic confidence levels to the corrections.Some results on the structure of multipoles in the study of snarks
http://hdl.handle.net/2117/27888
Title: Some results on the structure of multipoles in the study of snarks
Authors: Fiol Mora, Miquel Àngel; Vilaltella Castanyer, Joan
Abstract: Multipoles are the pieces we obtain by cutting some edges of a cubic graph in one or more points. As a result of the cut, a multipole M has vertices attached to a dangling edge with one free end, and isolated edges with two free ends. We refer to such free ends as semiedges, and to isolated edges as free edges. Every 3-edge-coloring of a multipole induces a coloring or state of its semiedges, which satisfies the Parity Lemma. Multipoles have been extensively used in the study of snarks, that is, cubic graphs which are not 3-edge-colorable. Some results on the states and structure of the so-called color complete and color closed multipoles are presented. In particular, we give lower and upper linear bounds on the minimum order of a color complete multipole, and compute its exact number of states. Given two multipoles M1 and M2 with the same number of semiedges, we say that M1 is reducible to M2 if the state set of M2 is a non-empty subset of the state set of M1 and M2 has less vertices than M1. The function v(m) is defined as the maximum number of vertices of an irreducible multipole with rn semiedges. The exact values of v(m) are only known for m <= 5. We prove that tree and cycle multipoles are irreducible and, as a byproduct, that v(m) has a linear lower bound.Tue, 12 May 2015 10:08:14 GMThttp://hdl.handle.net/2117/278882015-05-12T10:08:14ZFiol Mora, Miquel Àngel; Vilaltella Castanyer, Joannocubic graph, edge-coloring, snark, multipole, Parity Lemma, states, color complete, color closed, separable, irreducible, tree, cycle, linear recurrence, GRAPHSMultipoles are the pieces we obtain by cutting some edges of a cubic graph in one or more points. As a result of the cut, a multipole M has vertices attached to a dangling edge with one free end, and isolated edges with two free ends. We refer to such free ends as semiedges, and to isolated edges as free edges. Every 3-edge-coloring of a multipole induces a coloring or state of its semiedges, which satisfies the Parity Lemma. Multipoles have been extensively used in the study of snarks, that is, cubic graphs which are not 3-edge-colorable. Some results on the states and structure of the so-called color complete and color closed multipoles are presented. In particular, we give lower and upper linear bounds on the minimum order of a color complete multipole, and compute its exact number of states. Given two multipoles M1 and M2 with the same number of semiedges, we say that M1 is reducible to M2 if the state set of M2 is a non-empty subset of the state set of M1 and M2 has less vertices than M1. The function v(m) is defined as the maximum number of vertices of an irreducible multipole with rn semiedges. The exact values of v(m) are only known for m <= 5. We prove that tree and cycle multipoles are irreducible and, as a byproduct, that v(m) has a linear lower bound.