Iterated nonexpansive mappings

We present a further study on fixed point theory for the so called iterated nonexpansive mappings, that is, mappings which are nonexpansive along the orbits. They are a direct generalization of the contraction type maps studied by Rheinboldt in the late sixties of the last century. This is a wide class of nonlinear mappings including several families of generalized nonexpansive mappings appearing in the recent litherature.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Calefacción de viviendas por guardapolvos radiantes

Tesis (Ingeniero Constructor)El guardapolvo radiante es un sistema de calefacción basado en la circulación de agua caliente através de las tuberías que forman su estructura, la que cede la energía calórica al recirÁo mediante los fenómenos físicos de radiación y convección. Es un sistema de fácil dimensionamiento, de reducido costo y con las mismas cualidades de los sistemas actuales. En el desarrollo del presente trabajo se expone de forma clara los conceptos básicos de calefacción, la normativa vigente y la forma de distribución de los sistemas actuales, por otra parte, se detalla su estructura, los elementos complementarios, el calculo térmico de la vivienda a calefaccionar y la energía calórica cedida por la tubería al ambiente, para concluir con un estudio técnico económico entre el guardapolvo radiante versus una opción equivalente, los radiadores, donde los costos presentan variaciones importantes. El guardapolvo radiante depende de dos variables, el perímetro del recinto y el requerimiento energético del mismo. El primero determina la longitud del guardapolvo y el segundo la energía calórica que necesita la vivienda, ambas variables determinan la cantidad de tuberías que integran el sistema. Por otra parte, la temperatura de equilibrio sólo se logra cuando el recinto de mayor requerimiento energético alcanza su temperatura óptima. Como principales ventajas del sistema se destacan su gran adaptabilidad, el ahorro inducido en el tiempo y una proximidad ideal a la curva de calefacción. Por ultimo, el guardapolvo radiante como todo sistema de calefacción presenta debilidades, tales como, una puesta en servicio lenta, no es recomendable para grandes espacios o para recintos que requieran más de dos servicios distribución, debido a su elevado costo de implementación.The dust cover is a radiant heating system based on the movement of hot water through pipes that form its structure, which gave the heat energy to the site through the physical phenomena of radiation and convection. It is a system for easy sizing of reduced cost and with the same qualities of current systems. In undertaking this work sets out in c1ear the basic concepts of heating, the current rules and form of distribution of current systems, moreover, detailing its structure, elements complementary, the Thermal calculation of housing heating and heat energy transferred by pipeline to the environment, concluding with a technical study from economic duster cover radiant versus an option equivalent, the radiators, where costs have significant variations The duster cover radiant depends on two variables, the perimeter of the compound and the order of the same energy. The first determines the length of the canopy and the second heat energy it needs housing, both variables determine the amount of pipes that make up the system. On the other hand, the temperature balance is achieved only when the compound of higher energy demand reaches its optimum temperature As a majar system advantages are its high adaptability, the savings in time and induced an ideal proximity to the heating curve Finally, the duster cover radiant heating system as a whole presents weaknesses, such as an in-service slow, it is not recommended for larger spaces or enclosures that require more than two distribution services, due to its high cost of implementatio

Thermoelectric transport of mesoscopic conductors coupled to voltage and thermal probes

We investigate basic properties of the thermopower (Seebeck coefficient) of phase-coherent conductors under the influence of dephasing and inelastic processes. Transport across the system is caused by a voltage bias or a thermal gradient applied between two terminals. Inelastic scattering is modeled with the aid of an additional probe acting as an ideal potentiometer and thermometer. We find that inelastic scattering reduces the conductor's thermopower and, more unexpectedly, generates a magnetic-field asymmetry in the Seebeck coefficient. The latter effect is shown to be a higher-order effect in the Sommerfeld expansion. We discuss our result using two illustrative examples. First, we consider a generic mesoscopic system described within random matrix theory and demonstrate that thermopower fluctuations disappear quickly as the number of probe modes increases. Second, the asymmetry is explicitly calculated in the quantum limit of a ballistic microjunction. We find that asymmetric scattering strongly enhances the effect and discuss its dependence on temperature and Fermi energy.Comment: 4+ pages, 2 figures and supplementary material. Published versio

Lie symmetries of birational maps preserving genus 0 fibrations

Preprint.We prove that any planar birational integrable map, which preserves a fibration given by genus $0$ curves has a Lie symmetry and some associated invariant measures. The obtained results allow to study in a systematic way the global dynamics of these maps. Using this approach, the dynamics of several maps is described. In particular we are able to give, for particular examples, the explicit expression of the rotation number function, and the set of periods of the considered maps.Preprin

g-Factor anisotropy of hole quantum wires induced by the Rashba interaction

We present calculations of the g factors for the lower conductance steps of 3D hole quantum wires. Our results prove that the anisotropy with magnetic field orientation, relative to the wire, originates in the Rashba spin-orbit coupling. We also analyze the relevance of the deformation, as the wire evolves from 3D towards a flat 2D geometry. For high enough wire deformations, the perpendicular g factors are greatly quenched by the Rashba interaction. On the contrary, parallel g factors are rather insensistive to the Rashba interaction, resulting in a high g factor anisotropy. For low deformations we find a more irregular behavior which hints at a sample dependent scenario.Comment: 7 pages, 6 figures (expanded from previous version