Modelo bidimensional de transmisión de calor en tableros de puente

RESUMEN La influencia de efectos térmicos en tableros de puentes ha sido objeto de interés por los proyectistas en las últimas dos décadas, abordáiidose el análisis de la transmisión de calor en los mismos y las condiciones térmicas a que está sometido. La evaluación numérica del problema se ha reducido hasta el presente, a modelos de transmisión unidimensionales, que pueden representar aceptablemente tableros tipo losa, especialmente en su parte central. No obstante, los efectos producidos por gradientes térmicos son más acusados en secciones de paredes delgadas y en los bordes del tablero. Esto lia motivado el desarrollo por los autores de un programa de cálculo bidimensiorial que permita el estudio del campo térmico en una sección completa de la forma inás realista posible. SUMMARY The thermal effects on bridge decks has been a siibject of iilt,erest during the last two decades, beginning the analysis of heat conduction in the deck and the thermal conditions which deal with it. The numerical handling of the problem had been reduced up to the present time, to one-dimensional models of lieat transmission, which can only represent reasonably slab decks, mainly in llie central area. Altliough, tlie most important effects produced by thermal gradients are located in selections with thin walls and in the borders of the deck. The authors have developed a two-dimensional model of lieat conduction that reproduce the temperature field in a complete section of tlie bridge in a realistic manner.Peer Reviewe

The term structure of country risk and valuation in emerging markets

Most practitioners add the country risk to the discount rate when valuing projects in Emerging Markets. In addition to the problems already pointed out in the literature, in this paper we claim that such practice leads to a pro-cyclical bias in the valuation of long-term projects. The mismatch between the duration of the project and the duration of the most widely used measure of country risk, J. P. Morgan's EMBI, leads to an overvaluation of long-term projects in good times (upward sloping default risk) and to an undervaluation of them when short-term default risk is high (the contrary is true with respect to short-term projects.) Using sovereign bond data from five Emerging Markets, we estimate a simple model that captures most of the variation of default probabilities at different horizons for a given country at one point in time. This model can be used to solve the misestimation problem.Departamento de Economí

The term structure of country risk and valuation in emerging markets

Most practitioners add the country risk to the discount rate when valuing projects in Emerging Markets. In addition to the problems already pointed out in the literature, in this paper we claim that such practice leads to a pro-cyclical bias in the valuation of long-term projects. The mismatch between the duration of the project and the duration of the most widely used measure of country risk, J. P. Morgan's EMBI, leads to an overvaluation of long-term projects in good times (upward sloping default risk) and to an undervaluation of them when short-term default risk is high (the contrary is true with respect to short-term projects.) Using sovereign bond data from five Emerging Markets, we estimate a simple model that captures most of the variation of default probabilities at different horizons for a given country at one point in time. This model can be used to solve the misestimation problem.Departamento de Economí

Extracorporeal membrane oxygenation improves survival in a novel 24-hour pig model of severe acute respiratory distress syndrome

Indexación: Web of Science; Pub Med CentralExtracorporeal membrane oxygenation (ECMO) is increasingly being used to treat severe acute respiratory distress syndrome (ARDS). However, there is limited clinical evidence about how to optimize the technique. Experimental research can provide an alternative to fill the actual knowledge gap. The purpose of the present study was to develop and validate an animal model of acute lung injury (ALI) which resembled severe ARDS, and which could be successfully supported with ECMO. Eighteen pigs were randomly allocated into three groups: sham, ALI, and ALI + ECMO. ALI was induced by a double-hit consisting in repeated saline lavage followed by a 2-hour period of injurious ventilation. All animals were followed up to 24 hours while being ventilated with conventional ventilation (tidal volume 10 ml/kg). The lung injury model resulted in severe hypoxemia, increased airway pressures, pulmonary hypertension, and altered alveolar membrane barrier function, as indicated by an increased protein concentration in bronchoalveolar fluid, and increased wet/dry lung weight ratio. Histologic examination revealed severe diffuse alveolar damage, characteristic of ARDS. Veno-venous ECMO was started at the end of lung injury induction with a flow > 60 ml/kg/min resulting in rapid reversal of hypoxemia and pulmonary hypertension. Mortality was 0, 66.6 and 16.6% in the SHAM, ALI and ALI + ECMO groups, respectively (p < 0.05). This is a novel clinically relevant animal model that can be used to optimize the approach to ECMO and foster translational research in extracorporeal lung support.http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4931177

The Term Structure of Country Risk and Valuation in Emerging Markets

Fil: Cruces, Juan José. Universidad de San Andrés. Departamento de Economía; Argentina.Fil: Buscaglia, Marcos. Universidad de San Andrés. Departamento de Economía; Argentina.Fil: Alonso, Joaquín. Universidad de San Andrés. Departamento de Economía; Argentina

Aplicaciones de la Teoría de Campos

Con esta publicación los autores pretenden cubrir el vacío existente en la literatura técnica habitual, dadas las diferentes ramas que se tratan en la misma, y que deberían ser obtenidas de al menos cuatro libros diferentes. El objetivo principal, es facilitar a los alumnos de la Ingeniería de Caminos, la preparación de la segunda parte de la asignatura 'Teoría de Campos'. Pretende servir de guía para unificar criterios y notaciones y mostrar la semejanza que existe en cuanto a principios y métodos de resolución de problemas de Campos, en áreas tan diversas como el electromagnetismo, el flujo de medios permeables, la hidrodinámica o la conducción de calor en sólidos, de aplicación en Ingeniería Civil. Muchas de las explicaciones desarrolladas van acompañadas de figuras y gráficos, para su mejor comprensión.CantabriaES

A Testbed for GNSS-Based Positioning and Navigation Technologies in Smart Cities : the HANSEL Project

Altres ajuts: European Space Agency (AO/1-9494/18/NL/CRS)In urban contexts, the increasing density of electronic devices equipped with Global Navigation Satellite System (GNSS) receivers and complementary positioning technologies is attracting research and development efforts devoted to an improvement of the quality of life towards the smart city paradigm. Vehicular and pedestrian positioning and navigation capabilities are among the major drivers for innovation in this process. Ultra-low-cost electronics such as smartphones and Internet of Things (IoT) sensors aim at providing accurate and reliable positioning solutions through a set of promising solutions. Among these, snapshot positioning allows to remotely perform the post-processing of GNSS signals in IoT sensor networks while Wi-Fi™ ranging and cooperative positioning provide auxiliary anchors of opportunity to enhance indoor/outdoor positioning capabilities. This paper presents an innovative platform to perform a centralised testing and assessment of such positioning and navigation technologies along with a set of results obtained in the context of the European project HANSEL, by relying on current network technologies and infrastructures (i.e., Wi-Fi™ and cellular connectivity)