Hardy-Littlewood-Sobolev Inequalities via Fast Diffusion Flows

We give a simple proof of the $\lambda = d-2$ cases of the sharp Hardy-Littlewood-Sobolev inequality for $d\geq 3$, and the sharp Logarithmic Hardy-Littlewood-Sobolev inequality for $d=2$ via a monotone flow governed by the fast diffusion equation

Global solutions for the one dimensional Water-Bag model

International audienceIn this paper we study a special type of solution for the one dimensional Vlasov-Maxwell equations. We assume that initially the particle density is constant on its support in the phase space and we are looking for solutions with particle density having the same property at any time t > 0. More precisely, for each x the support of the density is assumed to be an interval [p,P] with end-points varying in space and time. We analyze here the case of weak and strong solutions for the effective equations verified by the end-points and the electric field (water-bag model) in the relativistic setting

Monte Carlo gPC methods for diffusive kinetic flocking models with uncertainties

In this paper we introduce and discuss numerical schemes for the approximation of kinetic equations for flocking behavior with phase transitions that incorporate uncertain quantities. This class of schemes here considered make use of a Monte Carlo approach in the phase space coupled with a stochastic Galerkin expansion in the random space. The proposed methods naturally preserve the positivity of the statistical moments of the solution and are capable to achieve high accuracy in the random space. Several tests on a kinetic alignment model with self propulsion validate the proposed methods both in the homogeneous and inhomogeneous setting, shading light on the influence of uncertainties in phase transition phenomena driven by noise such as their smoothing and confidence band

Simulation of a solar assisted counterflow tunnel dehydrator

A widely used class of vegetable dehydration systems are the “tunnel-and-truck” dehydrators, where the prepared material lies over horizontal trays stored in trucks which move discontinuously in opposite direction of the air flow. This way the driest product is facing the inlet hot and dry air blowed to the system. When product of one truck is ready, is removed from the tunnel leaving space for advance the remaining truck one place forward. This way, a new truck full of wet product can be inserted at the end of the tunnel. The hermal energy required for the process can be supplied by several sources including gas, biomass, solar energy or a combination of them. Solar energy is for free but reaches the Earth with quite a low flux and a strongly fluctuating rate. This imposes the need of special designs and control strategies. This paper presents a study based on simulation models of the dehydrator and the solar thermal system. The dehydrator simulation model is tuned to match experimental data from a particular prototype based on fossil fuel. A solar system simulation model is then applied to the analysis of different design options.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Essays on political accountability and selection

The aim of this thesis is to contribute to the political agency literature by analysing theoretically how media can enhance political accountability and selection. In this thesis, I identify and analyse two channels in which media can affect political accountability and selection. First, media spillovers can improve voters' imperfect information and promote politicians' discipline. Second, journalism can affect the distribution of candidates' quality across levels of government. The thesis is composed of three chapters. In Chapter 1, I present a theoretical model that analyses how voters use information from media spillovers to discipline politicians, but the spillovers depend on the geographic localization of a jurisdiction. The yardstick competition model demonstrates that within isolated jurisdictions (without media spillovers) politicians are more likely to subtract private rents. Whereas in a jurisdiction connected with two neighbouring jurisdictions, politicians have a lower probability of engaging in rent extraction. Moreover, I also show that even incumbents in isolated jurisdictions have a lower probability of engaging in obtaining private rents due to positive spillovers from neighbouring jurisdictions via voters' incumbency advantage. Chapter 2 theoretically analyses the effects of a journalist on the distribution of bad and good candidates across levels of government. Specifically, how bad (good) candidates self-select to local or national office anticipating the journalist's decision to investigate at local or national level. In the model, candidates' decisions are driven by the relative difference in the rewards for being the representative at a local or national office; and in the case of bad candidates also by the potential scandal cost of being exposed by the journalist. The theoretical model demonstrates that increasing the scandal cost of being exposed in a journalist report, does not deter bad candidates from running nationally (when the reward ratio is large enough). Indeed, it only makes that both, bad and good candidates to be distributed evenly across levels of government. Also, I found that when the reward ratio is on a specific range, increasing the scandal cost of being exposed in a journalist report creates only two opposite types of equilibria: one in which a bad candidate runs locally, whereas, in the other one, a good candidate runs locally. Moreover, I found a non-monotonic relationship between the probability of a bad candidate being elected at a local level and the reward ratio. Chapter 3 provides a brief description and an overview of the political system in Mexico. In particular, it describes the economic and political consequences that a one-party hegemony has had on the political corruption and accountability in Mexico. As the evidence suggests, the characteristics of the Mexican political system along with the hegemony, high centralized public finances, and a lack of electoral punishment have increased Mexico's political corruption, and ultimately reduced political accountability

Structural and numerical identifiability of thermal resistances in plate fin-and-tube heat exchangers using manufacturer catalog data

Plate fin-and-tube heat exchangers, commonly known as heating/cooling coils, are widely used in HVAC systems to transfer heat to or from air. A problem of practical interest in coil simulation is to identify the thermal resistances on the air and liquid sides using manufacturer catalog data. Manufacturers rarely provide detailed information (geometry and circuitry) of the coils they sell or install in factory-made equipment such as air handling units or fan-coils; they just report the performance of the coil at a few typical operating conditions. This paper examines whether it is mathematically possible to back-calculate the thermal resistances on the air and liquid sides using a set of performance data that is disturbed by noise (e.g. measurement errors) and consists of operating cases in which none of the two thermal resistances can be neglected. The first part of the paper discusses the structural identifiability problem, that is, the mathematical possibility of fitting Nusselt-type correlations for air and liquid, as well as a constant resistance for the wall. The second part of the paper discusses the possibility of calculating the numerical value of the parameters of the Nusselt correlations (constant or constant and exponent) using noisy data. The analysis is applied to a typical coil, which is simulated by means of a mathematical modelUniversidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Essays on political accountability and selection

The aim of this thesis is to contribute to the political agency literature by analysing theoretically how media can enhance political accountability and selection. In this thesis, I identify and analyse two channels in which media can affect political accountability and selection. First, media spillovers can improve voters' imperfect information and promote politicians' discipline. Second, journalism can affect the distribution of candidates' quality across levels of government. The thesis is composed of three chapters. In Chapter 1, I present a theoretical model that analyses how voters use information from media spillovers to discipline politicians, but the spillovers depend on the geographic localization of a jurisdiction. The yardstick competition model demonstrates that within isolated jurisdictions (without media spillovers) politicians are more likely to subtract private rents. Whereas in a jurisdiction connected with two neighbouring jurisdictions, politicians have a lower probability of engaging in rent extraction. Moreover, I also show that even incumbents in isolated jurisdictions have a lower probability of engaging in obtaining private rents due to positive spillovers from neighbouring jurisdictions via voters' incumbency advantage. Chapter 2 theoretically analyses the effects of a journalist on the distribution of bad and good candidates across levels of government. Specifically, how bad (good) candidates self-select to local or national office anticipating the journalist's decision to investigate at local or national level. In the model, candidates' decisions are driven by the relative difference in the rewards for being the representative at a local or national office; and in the case of bad candidates also by the potential scandal cost of being exposed by the journalist. The theoretical model demonstrates that increasing the scandal cost of being exposed in a journalist report, does not deter bad candidates from running nationally (when the reward ratio is large enough). Indeed, it only makes that both, bad and good candidates to be distributed evenly across levels of government. Also, I found that when the reward ratio is on a specific range, increasing the scandal cost of being exposed in a journalist report creates only two opposite types of equilibria: one in which a bad candidate runs locally, whereas, in the other one, a good candidate runs locally. Moreover, I found a non-monotonic relationship between the probability of a bad candidate being elected at a local level and the reward ratio. Chapter 3 provides a brief description and an overview of the political system in Mexico. In particular, it describes the economic and political consequences that a one-party hegemony has had on the political corruption and accountability in Mexico. As the evidence suggests, the characteristics of the Mexican political system along with the hegemony, high centralized public finances, and a lack of electoral punishment have increased Mexico's political corruption, and ultimately reduced political accountability

MODELO DE FACHADA VENTILADA CON DESECANTE PARA ACONDICIONAMIENTO DEL AIRE EXTERIOR DE VENTILACIÓN

Los sistemas de climatización y ventilación de edificios deben garantizar la calidad del aire interior y unas condiciones de temperatura y humedad que proporcione a los ocupantes un ambiente confortable y saludable, tal y como se recoge en el Código Técnico de la Edificación [1]. Con este fin, los materiales desecantes son utilizados en las unidades de tratamiento de aire. Combaten, en climas húmedos, la elevada carga latente de la zona, y son regenerados con aire caliente a partir de 50-60ºC, lo suficientemente bajo para que el calor lo proporcione un colector solar plano. En este trabajo se sustituye la rueda desecante convencional y se propone un nuevo diseño de una fachada ventilada, a la que se adhiere el material desecante. El aire de ventilación circula a través de la cámara de aire de la fachada, poniéndose en contacto con el material desecante, con el que transfiere masa y energía y, posteriormente, se somete a un tratamiento en una climatizadora convencional (batería de frío, enfriamiento evaporativo…) para ser impulsado a la zona. Cuando el desecante se satura y no puede adsorber más humedad, el sistema de fachada dispone de un captador solar que calienta el aire exterior hasta la temperatura necesaria para su regeneración. El diseño de dos columnas de fachada desecante permite alternar los modos de adsorción y desorción sin que se interrumpa el caudal de aire de ventilación. Planteadas las hipótesis, se desarrolla un modelo de la transferencia de calor y masa en la fachada. Se presenta el estudio de la simulación del caso base. Un estudio posterior permitirá la optimización de los parámetros más importantes: tipo de panel exterior, tipo y características del desecante y geometría del sistema, además del comportamiento para diferentes condiciones exteriores (aire y radiación solar).El trabajo se encuadra en el proyecto FAVEDES, financiado por la Secretaría de Estado de I+D+I del Ministerio de Economía y Competitividad dentro de la convocatoria INNPACTO 2011 y cuenta con la participación de Instituto Andaluz de Tecnología, Tecnalia, Grupo de Energética de la Universidad de Málaga, Astrawall Ibérica, b720 Arquitectos y Negarra