Numerical issues in threshold autoregressive modelling of time series

This paper analyses the contribution of various numerical approaches to making the estimation of threshold autoregressive time series more efficient. It relies on the computational advantages of QR factorizations and proposes Givens transformations to update these factors for sequential LS problems. By showing that the residual sum of squares is a continuous rational function over threshold intervals it develops a new fitting method based on rational interpolation and the standard necessary optimality condition. Taking as benchmark a simple grid search, the paper illustrates via Monte Carlo simulations the efficiency gains of the proposed tools

Inhomogeneous torsional creep problems in anisotropic Orlicz Sobolev spaces

In this paper, we study the asymptotic behavior of the sequence of solutions for a family of torsional creep-type problems, involving inhomogeneous and anisotropic differential operators, on a bounded domain, subject to the homogenous Dirichlet boundary condition. We find out that the sequence of solutions converges uniformly on the domain to a certain distance function defined in accordance with the anisotropy of the problem. In addition, we identify the limit problem via viscosity solution theory.Fil: Mihailescu, Mihai. University Of Craiova; RumaniaFil: Pérez Pérez, Maria Teresa. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Investigaciones Matemáticas "Luis A. Santaló". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Matemáticas "Luis A. Santaló"; Argentin

Regional and urban evaluation of an air quality modelling system in the European and Spanish domains

El impacto de la contaminación del aire es un tema crítico para el medioambiente y el clima. Una mala calidad del aire es un tema de importancia para la salud pública, especialmente en ambientes urbanos. El material particulado (PM), el ozono (O3) y el dióxido de nitrógeno (NO2) son los contaminantes más problemáticos en Europa y España. La Comisión Europea ha mostrado una gran preocupación por desarrollar técnicas que permitan incrementar el conocimiento sobre la dinámica de los contaminantes atmosféricos para asegurar el cumplimiento de la legislación y para informar a la población acerca de sus niveles. Además, la directiva europea 2008/50/CE establece la posibilidad de usar técnicas de modelización para informar sobre calidad del aire. Esta tesis doctoral está desarrollada en el marco de dos proyectos: El proyecto CALIOPE y el proyecto CICYT CGL2006-08903, ambos basados en la necesidad de desarrollar un sistema de calidad del aire que permita informar y entender los niveles de contaminación en Europa y España, con el objetivo de obtener un preciso pronóstico de la calidad del aire. Con ese propósito, el sistema de modelización CALIOPE se ha desarrollado con alta resolución espacial y temporal sobre Europa (12 km x 12 km y 15 capas, 1 hora), dominio madre, y España (4 km x 4 km y 15 capas, 1 hora), dominio anidado. CALIOPE consiste en un conjunto de modelos que tienen en cuenta la contaminación tanto antropogénica como natural. La disponibilidad del supercomputador MareNostrum, alojado en el Barcelona Supercomputer Center- Centro Nacional de Supercomputación, ha permitido trabajar a tan alta resolución. El objetivo principal de esta tesis es aumentar la confianza científica en el sistema CALIOPE, identificando sus puntos fuertes y débiles con un nivel de detalle que contribuya a establecer necesidades de mejora en el proceso de modelización. Por tanto, el presente trabajo ha evaluado espacial y temporalmente las simulaciones de calidad del aire sobre Europa y España en términos de O3, NO2, SO2, PM2.5 y PM10 en superficie sobre el año completo 2004. Para identificar el origen de las incertidumbres en la modelización del PM, su composición química ha sido también evaluada en ambos dominios. Las evaluaciones han sido realizadas sobre más de 150 estaciones de calidad del aire (más de 2 millones de datos experimentales). Además, esta tesis ha usado el sistema CALIOPE para analizar los patrones de calidad del aire sobre 2004, identificando claramente las áreas de contaminación. Las ideas más importantes que se desprenden de esta tesis son tres. Primero, las condiciones de contorno químicas basadas en un modelo global, como el LMDz-INCA2, son esenciales para modelizar el O3 troposférico sobre los dominios de estudio. Segundo, para simular la concentración de PM en el sur de Europa, tanto a escala rural como urbana, la contribución de polvo procedente del desierto del Sahara deber ser considerada debido a la proximidad al continente africano. La contribución del polvo del desierto a través del modelo BSC-DREAM8b ayuda satisfactoriamente a modelizar los picos de PM10 observados. Tercero, para ser capaz de modelizar la calidad del aire a escala urbana sobre España es esencial (1) una alta resolución espacial y temporal que permita describir fenómenos mesoescalares en áreas de topografía compleja , (2) un modelo de emisiones altamente desagregado como HERMES; (3) unos modelos que representen el estado actual del conocimiento en meteorología y química atmosféricaThe impact of air pollution is a critical topic in environment and climate. Poor air quality is an important public health issue, especially in urban environments. Particulate matter (PM), tropospheric ozone (O3) and nitrogen dioxide (NO2) are the main problematic pollutants in Europe and Spain. The European Commission has shown a great concern for developing actions that allow increasing the knowledge on dynamics of atmospheric pollutants to assure the accomplishment of legislation and to inform the population about their levels. The European directive 2008/50/EC establishes the possibility of using modelling techniques to assess air quality. This Ph.D. thesis is developed in the framework of two projects: the CALIOPE project and the CGL2006-08903 CICYT project, both based on the necessity to develop an air quality modelling system that allows assessing and understanding the air pollution levels in Europe and Spain, with the aim of obtaining a precise air quality forecast. For that purpose, the CALIOPE air quality modelling system has been developed with high spatial and temporal resolution over Europe (12 km x 12 km, 1 h), as a mother domain; and Spain (4 km x 4 km, 1 h), as the nested domain. The CALIOPE system consists in a set of models that take into account both anthropogenic and natural pollution. The availability of the MareNostrum supercomputer, held in Barcelona Supercomputing Center- Centro Nacional de Supercomputación, has allowed such configuration of the CALIOPE system. The main objective of the present Ph.D. thesis is to increase the scientific confidence on the CALIOPE system, identifying skills and weakness with a degree of detail that contributes to establish necessities of improvements in the modelling process. Therefore, the present work has spatially and temporally evaluated CALIOPE air quality simulations over Europe and Spain in terms of O3, NO2, SO2, PM2.5, PM10 concentrations over the full year 2004. In order to identify the origin of uncertainties in PM modelling, PM chemical composition has been also evaluated in both target domains. Evaluations have been performed across more than 150 air quality-monitoring stations and over more than 2 million of experimental data. Furthermore, this Ph.D. thesis has used the CALIOPE system to assess air quality pattern over the year 2004, identifying clearly the areas of air pollution. There are three major thrusts of the present Ph.D. thesis. First, chemical boundary condition based on a global model, such as LMDz-INCA2, becomes essential to model O3 background concentrations in the target domains. Second, to simulate PM concentration in southern Europe, both regional and urban scales, the contribution of dust from the Saharan desert should be taken into account, since that region is frequently affected by dust outbreaks due to its proximity to the African continent. The contribution of desert dust through the BSC-DREAM8b helps to satisfactory model the observed episodic PM10 concentration peaks. Even more, the contribution of sea-salt aerosol is especially important over coastal areas. Third, to be able to model the air quality in urban scale over Spain it is essential (1) a high spatial (4 km x 4 km and 15 layers) and temporal (1h) resolution that allows describing mesoscale phenomena in very complex terrains; (2) a high disaggregated emission model to describe the sources, such as HERMES; and (3) an state-of-the-science meteorological and chemical models. This Ph.D. thesis has demonstrated that CALIOPE system applied over Europe and Spain is a useful tool which may contribute to (1) forecast air pollution in urban/suburban areas with a pervasive influence of anthropogenic emissions on a local scale and over very complex terrains and meteorology patterns; (2) assess about air pollution, discriminating between anthropogenic and natural episodes; and (3) manage air pollution, by means of modification of urban strategies or requirements of the legislation

Obtaining quasi-static models using a frequency domain extraction methodology

© 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.”This contribution illustrates how a realistic nonlinear quasi-static model for FET-type devices can be extracted using an original frequency domain extraction technique. An ideal ‘made-up’ device is built from the measured bias dependence of a GaN medium power device. This ideal device is excited by two ideal voltage sources and its response (drain current) is used to illustrate how the extraction procedure can separate conduction and displacement current components provided the total current spectrum (or, alternatively, waveform) and control voltages are known.This work has been supported by the Junta de Andalucía under Grant (TIC2012-1237). Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

The Effect of Haptic Feedback on Basic Social. Interaction within Shared Virtual Environments

This paper describes an experiment that studies the effect of basic haptic feedback in creating a sense of social interaction within a shared virtual environment (SVE). Although there have been a number of studies investigating the effect of haptic feedback on collaborative task performance, they do not address the effect it has in inducing social presence. The purpose of this experiment is to show that haptic feedback enhances the sense of social presence within a mediated environment. An experiment was carried out using a shared desktop based virtual environment where 20 remotely located couples who did not know one another had to solve a puzzle together. In 10 groups they had shared haptic communication through their hands, and in another group they did not. Hence the haptic feedback was not used for completing the task itself, but rather as a means of social interacting – communicating with the other participant. The results suggest that basic haptic feedback increases the sense of social presence within the shared VE

Sales model: a preliminary approach and methodology

This work project aims at supporting managers in explaining and predicting sales of specificproducts based on a devised methodology. Product sales time series were analysed andprocessed in order to select the best model type: explanatory models (through ordinary leastsquares method), univariate models (Box Jenkins methodology) or dynamic models mixing upthe two previous approaches. An automatic procedure to put the methodology in practice wasimplemented using Python, due to the huge amount of product sales to be modelled. Theprocess was tested using data from more than 1500 products from Beiersdorf Lisbon. For thesake of confidentiality, the names of the products were modified. The most accurate models aredescribed and analyzed

Monastic Buildings: A Review About New Uses on Former Monasteries. The Portuguese Cistercian Case

This paper aims to present a review contribution to the history of the reform and renewal in the Portuguese Cistercian monasteries, throughout nine centuries of cultural and architectural history, but focusing on the new uses on former monasteries. The monastic Orders had a vital importance, both temporal and spatial, in the development of the urban fabric of cities. It must be considered that the transformation and development of the territory have been responsible for isolated buildings and settlements which have gradually been absorbed by the expansion of the urban fabric. The Cistercian Order played a remarkable role in the affirmation of Portugal (1143) and had an unquestionable position, since the medieval period, in the construction of a significant part of the Portuguese culture. The first Cistercian monasteries appeared in Portugal, in the 12th century, far from the urban context. Portuguese Cistercian monasteries became worthy examples of the European Cistercian architecture, although, over the time, they have been adapted, enlarged and transformed according to the styles of each epoch. The disappearance of the religious Orders, in 1834, and the successive owners adapted the monastic buildings to new uses. The monasteries have provided the contemporary city, especially from the 19th and 20th centuries, with expectant spaces or new fields of experimentation as diverse as rehabilitation, reuse, renovation and conversion. These are new spaces which adapt to new situations and new uses, thus updating themselves, so that the values of the present can be included and integrated into its history. Therefore, this paper aims to discuss, in which way the ideals and the realities of these monastic buildings and related urban spaces are divergent, but also a factor of city growth and cultural development.info:eu-repo/semantics/publishedVersio

The bacterial community composition of the surface microlayer in a high mountain lake

The existence of bacterioneuston in aquatic ecosystems is well established, but little is known about its composition and dynamics, particularly in lakes. The bacterioneuston underlies extreme conditions at the air-water boundary, which may influence its dynamics in a different way compared with the bacterioplankton. In this study, we assessed quantitative changes in major bacterial groups of the surface microlayer (SML) (upper 900 μm) and the underlying water (ULW) (0.2-0.5 m depth) of an alpine lake during two consecutive ice-free seasons. Analysis of the bacterial community composition was done using catalyzed reporter deposition FISH with oligonucleotide probes. In addition, several physicochemical parameters were measured to characterize these two water layers. Dissolved organic carbon was consistently enriched in the SML and the dissolved organic matter pool presented clear signals of photodegradation and photobleaching. The water temperature was generally colder in the SML than in the subsurface. The bacterial community of the SML and the ULW was dominated by Betaproteobacteria and Actinobacteria. The bacterial community composition was associated with different combinations of physicochemical factors in these two layers, but temporal changes showed similar trends in both layers over the two seasons. Our results identify the SML of alpine lakes as a microhabitat where specific bacterial members such as of Betaproteobacteria seem to be efficient colonizer

MIGRACIÓN MASCULINA Y CAMBIO EN LOS ROLES Y RELACIONES DE GÉNERO EN MADRE-ESPOSAS DE FAMILIAS DE SANTA ROSA RINCÓN DE JAIMES, TEJUPILCO, ESTADO DE MÉXICO

SE CENTRA EN CONOCER, ENTENDER E INTENTAR INTERPRETAR PARA COMPRENDER LAS RECONFIGURACIONES EN LAS RELACIONES Y ROLES DE GÉNERO EXPERIMENTADOS POR LAS MUJERES, A PARTIR DE LA MIGRACIÓN MASCULINA, EN LA LOCALIDAD SANTA ROSA RINCÓN DE JAIMES, UBICADA AL SUROESTE DEL ESTADO DE MÉXICO

Influence of the Flowing Conditions on the Galvanic Corrosion of the Copper/AISI 304 Pair in Lithium Bromide Using a Zero-Resistance Ammeter

[EN] In this work, the influence of Reynolds number (Re) on the galvanic corrosion of the copper/AISI 304 stainless steel pair in an 850 g/L lithium bromide solution was evaluated in a hydraulic circuit using a zero-resistance ammeter; this technique has the advantages that it can be used without disturbing the system under investigation and in continuous-time. Results show that copper is the anodic member of the pair for all the Re analyzed. The galvanic current density values are always greater under flowing than under stagnant conditions. A general tendency of galvanic current density to decrease with time is observed due to the formation of a film of corrosion products on copper surface. Under flowing conditions, initially, galvanic current density increases with Re; however, with time, this tendency is reversed. As Re increases, greater quantities of corrosion products are initially produced and, as a result, a thicker film is formed.This work was supported by the MICINN (reference number: CTQ2009-07518) and FEDER (Fondo Europeo de Desarrollo Regional). The authors also wish to express their gratitude to Asunción Jaime for her translation assistance.Montañés, M.; Sánchez Tovar, R.; Garcia-Anton, J.; Pérez-Herranz, V. (2010). Influence of the Flowing Conditions on the Galvanic Corrosion of the Copper/AISI 304 Pair in Lithium Bromide Using a Zero-Resistance Ammeter. INTERNATIONAL JOURNAL OF ELECTROCHEMICAL SCIENCE. 5(12):1934-1947. http://hdl.handle.net/10251/98931S1934194751