3,659 research outputs found

    Phase equilibria and P-T-X (Fe-Mg) relations involving GT-St-Cd-Als-Bi-Mu-Qz-Kfs-H20 in medium-high grade metapelites (KFASH,KMASH and KFMASH systems)

    Get PDF
    En rocas metapelíticas de diversas áreas en el Hercínico de la Península Ibérica se observan a menudo las siguientes reacciones: Estaurolita + moscovita + cuarzo = biotita + Al2SiO5+ H2O Granate + moscovita = Al2SiO5 + biotita ± cuarzo Biotita + Al2SiO5 + cuarzo = cordierita + feldespato potásico + H2O. Se han estudiado en el sistema con K2O -FeO- Al2O3-SiO2-H2O (KFASH) tres asociacioness con Bi-Mu-St-Als-Qz- H2O además de Cd-Gt-Fk, eliminando en cada una de ellas una de las tres últimas fases. La expansión de las reacciones que se obtienen con estas asociaciones, en superficies divariantes a través del espacio P-T-X(Fe-Mg), se realizó estudiando la asociación GtSt- Cd-Bi-Mu-Fk-Als-Qz- H2 en el sistema KFMASH con una relación Fe/Fe+Mg según Gt St Bi Cd, tal como se observa en la mayoría de roca pelíticas. A partir de las anteriores redes se ba obtenido otra para condiciones de PH20=Pt baja fugacidad de oxígeno (tampón QFM), y exceso de moscovita y cuarzo. Las pendientes de las reacciones en esta última red se calcularon para diferentes condiciones poTo Se han obtenido las relaciones teóricas P-T-X(Fe-Mg) para tres reacciones univariantes y trece divariantes. La red confirma la imposibilidad de la coexistencia entre estaurolita y feldespato potásico y entre granate, cordierita y moscovita. Se constata, además, la extensión de los campos de estabilidad de Gt-St, Cd-St y Gt-Cd en metapelitas pobres en moscovita.In different areas of the Hercynian in the Iberian Peninsula sorne reactions are repeatedly observed in pelites, these reactions are: Staurolite + muscovite + quartz = Biotite+ Al2SiOs+ H20 Garnet + muscovite = AI2SiOs+ biotite+ quartz Biotite + Al2SiOs + quartz = Cordierite + K feldspar+Hp In order to examinate the P-T stability fields of tbese, and otber similar reactions, aH the univariant equilibria in multisystems with Gt-Cd-St-Bi-Mu-Als-Qz-HP, Gt-St-Bi-Mu-Fk-AIs-QzHp and Cd-St-Bi-Mu-Fk-AIs-Qz-H20 in Kp-FeO-AI20 r Si02-H20 (KFASH) system have been calculated, and their corresponding P-T grids have been constructed. The expansion of these reactions into divariant surfaces through the P-T-X (Fe-Mg) space was made by studying the assemblage Gt-Cd-St-Bi-Mu-Fk-AIs-Qz-HP in Kp-FeO-MgO-AIP3-Si02-Hp (KFMASH) with a Fe/Fe+Mg relationship Gt>St>Bi>Cd such as observed in most of natural pelites. A resultant grid was obtained by combining those obtained in the aboye systerns. This grid has been P-T located for PH2o =P" near QFM buffer, and excess muscovite and quartz conditions Reaction slopes in this grid were calculated within different P-T surroundings from thermodynamic data as weH as by considering the existing experimental data. In addition to the stability fields of reactions tbe P-T-XFe_Mg theoric relations for three univariant and thirteen divariant reactions have been obtained. The grid confirms the imposibility of staurolite-K feldspar and Garnet-Cordierite-Muscovite coexistence, as weH as the extension of the stability fields for Garnet-Staurolite, Cordierite-Staurolite and Garnet-Cordierite assemblages in muscovite-poor metapelites

    Análisis de los sistemas actuales en oftalmología para el estudio de enfermedades relacionadas con la modificación geométrica de la arquitectura corneal

    Get PDF
    [ES] El análisis de la morfología corneal es un procedimiento muy útil en el diagnóstico clínico de determinadas patologías oculares, especialmente las relacionadas con alteraciones ectásicas corneales. Desde la aparición de los sistemas basados en Discos de Plácido a los sistemas que incorporan la fotografía Scheimpflug, existe una variedad de instrumentos que ofrecen la posibilidad de analizar con gran precisión parámetros de la morfología corneal. En esta comunicación se revisan los diversos instrumentos que han sido utilizados para caracterizar la morfología corneal, estando todos influenciados, en mayor o menor medida, por factores como la rapidez de adquisición de datos y la estabilidad de la película lagrimal. [ENG] The analysis of the corneal shape is a very useful process that permits the clinical diagnosis of determined ocular pathologies, especially those related with corneal ectatic disorders. From the appearance of the systems based on the Placido-disc technology to the new systems that combine the accurate Scheimpflug photography, there are a variety of ophthalmic instruments that permit to analyze with high accuracy some parameters of the corneal shape. This communication reviews the different systems that have been used to characterize the corneal morphology, being all of them influenced, to a greater or lesser extent, by factors such as the speed for data acquisition and the stability of the tear film.Centro Universitario de la Defensa. Escuela de Turismo de Cartagena. Escuela Técnica Superior de Ingeniería Industrial UPCT. Escuela Técnica Superior de Ingeniería de Telecomunicación (ETSIT). Escuela de Ingeniería de Caminos y Minas (EICM). Escuela de Arquitectura e Ingeniería de Edificación (ARQ&IDE). Parque Tecnológico de Fuente Álamo. Navantia. Campus Mare Nostrum. Estación Experimental Agroalimentaria Tomás Ferr

    A Robot-Sensor Network Security Architecture for Monitoring Applications

    Get PDF
    This paper presents SNSR (Sensor Network Security using Robots), a novel, open, and flexible architecture that improves security in static sensor networks by benefiting from robot-sensor network cooperation. In SNSR, the robot performs sensor node authentication and radio-based localization (enabling centralized topology computation and route establishment) and directly interacts with nodes to send them configurations or receive status and anomaly reports without intermediaries. SNSR operation is divided into stages set in a feedback iterative structure, which enables repeating the execution of stages to adapt to changes, respond to attacks, or detect and correct errors. By exploiting the robot capabilities, SNSR provides high security levels and adaptability without requiring complex mechanisms. This paper presents SNSR, analyzes its security against common attacks, and experimentally validates its performance

    La educación emprendedora en Andalucía. Un enfoque integrado

    Get PDF
    When evaluating the relevance of actions within the area of entrepreneurship education, the quite remarkable national and regional differences regarding entrepreneurial culture, entrepreneurial potential and, of course, the business structure, have to be taken into account. Based on these differences, there is a need to specifically design entrepreneurial education policies which take into account the strengths and weaknesses of the business structure of each region. This paper aims to identify the structural characteristics of the Andalusian entrepreneurial model in comparison with that of other Spanish regions. To do this, a database of over 1000 companies have been used coming from the Research Project (Ref. P09- SEJ -4857) carried out by the "SMEs and economic development" research group (SEJ -128) of the University of Seville. This information will also be complemented with regional reports from the GEM project. From these two data sources, an eminently qualitative profile of the structural weaknesses of existing businesses and their entrepreneurs in Andalusia will be established. From this analysis of regional needs, we will raise our differential proposition for an embedded education towards entrepreneurship. It will identify and include the content and pedagogical techniques necessary to overcome these weaknesses of the regional business community.Al evaluar la pertinencia de las acciones en el ámbito de la educación empresarial, las notables diferencias nacionales y regionales con respecto a la cultura emprendedora, el potencial empresarial y, por supuesto, la estructura empresarial, han de ser tenidos en cuenta. Sobre la base de estas diferencias, hay una necesidad de diseñar políticas específicas de educación emprendedora que tengan en cuenta las fortalezas y debilidades de la estructura empresarial de cada región. Este trabajo tiene como objetivo identificar las características estructurales del modelo empresarial andaluz en comparación con el de otras regiones españolas. Para ello, se ha usado una base de datos de más de 1.000 empresas procedente del Proyecto de Investigación (Ref. P09- SEJ -4857) llevado a cabo por el grupo de investigación "PYME y desarrollo económico” (SEJ -128) de la Universidad de Sevilla. Esta información también se complementará con los informes regionales del proyecto GEM. A partir de estas dos fuentes de datos, se establecerá un perfil eminentemente cualitativo de las debilidades estructurales de las empresas existentes en Andalucía y de sus empresarios. A partir de este análisis de las necesidades regionales, vamos a plantear nuestra propuesta diferencial para una educación emprendedora integrada. Se identificará e incluirá el contenido y las técnicas pedagógicas necesarias para superar estas debilidades de la comunidad empresarial regional

    Mathematical analysis and numerical resolution of a heat transfer problem arising in water recirculation

    Get PDF
    This work is devoted to the analysis and resolution of a well-posed mathematical model for several processes involved in the artificial circulation of water in a large waterbody. This novel formulation couples the convective heat transfer equation with the modified Navier–Stokes system following a Smagorinsky turbulence model, completed with a suitable set of mixed, nonhomogeneous boundary conditions of diffusive, convective and radiative type. We prove several theoretical results related to existence of solution, and propose a full algorithm for its computation, illustrated with some realistic numerical examples.Ministerio de Economía y Competitividad | Ref. MTM2015-65570-PXunta de Galicia | Ref. ED431D 2017/1

    Controlling eutrophication by means of water recirculation: An optimal control perspective

    Get PDF
    In this work, the artificial recirculation of water is presented and analyzed, from the perspective of the optimal control of partial differential equations, as a tool to prevent eutrophication effects in large waterbodies. A novel formulation of the environmental problem, based on the coupling of nonlinear models for hydrodynamics, water temperature and concentrations of the different species involved in the eutrophication processes, is introduced. After a complete and rigorous analysis of the existence of optimal solutions, a full numerical algorithm for their computation is proposed. Finally, some numerical results for a realistic scenario are shown, in order to prove the efficiency of our approachThe authors would like to thank the anonymous referees for their interesting comments, suggestions and corrections, as they have greatly contributed to improve the quality of the manuscript. The authors were partially supported by Xunta de Galicia, Spain, project ED431C 2019/02, and by the Agencia Estatal de Investigación (AEI) of Spain under grant MTM2016-75140-P, co-financed by the European Community fund FEDERS

    On existence and uniqueness of solution for a hydrodynamic problem related to water artificial circulation in a lake

    Get PDF
    In this work we introduce a well-posed mathematical model for the processes involved in the artificial circulation of water, in order to avoid eutrophication phenomena, for instance, in a lake. This novel and general formulation is based on the modified Navier–Stokes equations following the Smagorinsky model of turbulence, and presenting a suitable nonhomogeneous Dirichlet boundary condition. For the analytical study of the problem, we prove several theoretical results related to existence, uniqueness and smoothness for the solution of this recirculation model.Xunta de Galicia | Ref. ED431C 2018/50Ministerio de Economía y Competitividad | Ref. MTM2015-65570-

    Effects of different maturity status on change of direction performance of youth tennis players

    Get PDF
    [EN] The aim of this study was to examine the maturational status (i.e., peak height velocity [PHV]) differences in neuromuscular performance (i.e., vertical jump, linear sprint, change of direction (COD) using different tests, and change of direction deficit [CODD]) of young tennis players. One hundred and two tennis players (70 boys and 52 girls; age 13.9 ± 2.0 years, body mass 53.3 ± 12.7 kg, height 163.1 ± 11.9 cm) participated in the study and were divided into Pre-PHV (n = 26), Circa-PHV (n = 33) and Post-PHV (n = 43) groups. Testing included speed (5, 10, and 20 m), COD tests (i.e., modified 5-0-5, pro-agility and hexagon), and bilateral/unilateral countermovement jump (CMJ). Pre- and Circa-PHV players presented lower levels of performance in jumping ability (i.e., both bilateral and unilateral CMJs; P < 0.001; ES: 0.85 to 0.98), linear sprints (5 to 20 m; P < 0.05 to < 0.001; ES: 0.67 to 1.19) and COD ability tests (modified 5-0-5 test, proagility and hexagon) compared to the Post-PHV players. Moreover, Pre-PHV players presented lower CODD% (p < 0.05; ES: 0.68–0.72) than Post-PHV for both forehand and backhand sides, and Circa-PHV showed lower values in the CODD of the rolling situation to the forehand side (p < 0.05; ES: 0.58). Among the COD tests, the pro-agility test seems to be a simple, easy-to-implement and reliable test, which can provide interesting information about the COD with higher entry speeds. Moreover, specific training strategies related to the PHV and focused not only on the neuromuscular training and COD workouts, but also on maximizing motor skill proficiency, should be recommended.S

    Multilogistic Regression using Initial and Radial Basis Function covariates

    Get PDF
    This paper proposes a hybrid multilogistic model, named MultiLogistic Regression using Initial and Radial Basis Function covariates (MLRIRBF). The process for obtaining the coefficients is carried out in several steps. First, an Evolutionary Programming (EP) algorithm is applied, aimed to produce a RBF Neural Network (RBFNN) with a reduced number of RBF transformations and the simplest structure possible. Then, the input space is transformed by adding the nonlinear transformations of the input variables given by the RBFs of the best individual in the last generation. Finally, a maximum likelihood optimization method determines the coefficients associated with a multilogistic regression model built on this transformed input space. In this final step, two different multilogistic regression algorithms are applied, one that considers all initial and RBF covariates (MLRIRBF) and another one that incrementally constructs the model and applies cross-validation, resulting in an automatic covariate selection (MLRIRBF*). The methodology proposed is tested using six benchmark classification problems from well-known machine learning problems. The results are compared with the corresponding multilogistic regression methodologies applied over the initial input space, to the RBFNNs obtained by the EP algorithm (RBFEP) and to other competitive machine learning techniques. The MLRIRBF* models are found to be better than the corresponding multilogistic regression methodologies and the RBFEP method for almost all datasets, and obtain the highest mean accuracy rank when compared to the rest of methods in all datasets

    Populismo / José Luis Villacañas. Madrid: La Huerta Grande Editorial, 2015, 139 pp.

    Get PDF
    corecore