1,204 research outputs found

    Simulations of Melting of Encapsulated CaCl2·6H2O for Thermal Energy Storage Technologies

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    We present in this work simulations using the finite difference approximation in 2D for the melting of an encapsulated phase-change material suitable for heat storage applications; in particular, we study CaCl2·6H2O in a cylindrical encapsulation of internal radius 8 mm. We choose this particular salt hydrate due to its availability and economic feasibility in high thermal mass building walls or storage. Considering only heat conduction, a thermostat is placed far from the capsule, providing heat for the melting of the phase-change material (PCM), which is initially frozen in a water bath. The difference in density between the solid and liquid phases is taken into account by considering a void in the solid PCM. A simple theoretical model is also presented, based on solving the heat equation in the steady state. The kinetics of melting is monitored by the total solid fraction and temperatures in the inner and outer surfaces of the capsule. The effect of different parameters is presented (thermostat temperature, capsule thickness, capsule conductivity and natural convection in the bath), showing the potential application of the method to select materials or geometries of the capsule

    Researching the crisis

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    La crisis es un problema que afecta y preocupa a todas las personas, también al alumnado. Este problema puede ser trabajado y aprendido de forma significativa con una metodología de investigación escolar, que tiene en cuenta la aportación de los contenidos disciplinares, la significación para el alumnado y la relevancia del problema social. Desde estas bases, se muestra el diseño y la puesta en práctica de una unidad didáctica sobre la crisis, siguiendo un modelo de investigación escolar. Los contenidos trabajados en esta unidad permiten la integración de las distintas áreas curriculares y favorecen el logro de las competencias básicas.The crisis is a problem that affects and concerns all people, including the students. This problem can be worked with and learned significantly with school research methodology, which takes into account the contribution of the disciplinary content, the significance for students and the relevance of the social problem. From these bases, we show the design and implementation of a didactic unit on the crisis, following a model of school research. The contents worked in this unit allow the integration of curricular areas and promote the achievement of basic skill

    Lactic Acid Bacteria and Yeast Inocula Modulate the Volatile Profile of Spanish-Style Green Table Olive Fermentations

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    In this work, Manzanilla Spanish-style green table olive fermentations were inoculated with Lactobacillus pentosus LPG1, Lactobacillus pentosus Lp13, Lactobacillus plantarum Lpl15, the yeast Wickerhanomyces anomalus Y12 and a mixed culture of all them. After fermentation (65 days), their volatile profiles in brines were determined by gas chromatography-mass spectrometry analysis. A total of 131 volatile compounds were found, but only 71 showed statistical differences between at least, two fermentation processes. The major chemical groups were alcohols (32), ketones (14), aldehydes (nine), and volatile phenols (nine). Results showed that inoculation with Lactobacillus strains, especially L. pentosus Lp13, reduced the formation of volatile compounds. On the contrary, inoculation with W. anomalus Y12 increased their concentrations with respect to the spontaneous process, mainly of 1-butanol, 2-phenylethyl acetate, ethanol, and 2-methyl-1-butanol. Furthermore, biplot and biclustering analyses segregated fermentations inoculated with Lp13 and Y12 from the rest of the processes. The use of sequential lactic acid bacteria and yeasts inocula, or their mixture, in Spanish-style green table olive fermentation could be advisable practice for producing differentiated and high-quality products with improved aromatic profile.Gobierno de España-OliFilm-AGL-2013-48300-

    Estudio sobre las motivaciones para la práctica de la escalada en roca

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    El presente artículo estudia las razones que llevan a los escaladores en roca al aire libre a practicar este deporte, analizando las relaciones existentes entre estas motivaciones y el género. Para ello se empleó un cuestionario autoadministrado a una muestra de 146 escaladores (89 hombres y 57 mujeres) de 18 a 54 años de edad (media = 31,24 ± 6,96 años). Los resultados pusieron de manifiesto que las principales razones elegidas por los escaladores eran intrínsecas, destacando entre ellas el contacto con la naturaleza, la búsqueda de aventura, el reto personal y la diversión. Entre los motivos menos señalados encontramos la mejora de la imagen, la competición y el reconocimiento social. Por género, las escaladoras eligieron en mayor medida la diversión y la mejora de la imagen como motivos para escalar

    Influenza a from the rational choice theory: proposals for decision making in prevention policies

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    El artículo que presentamos es una reflexión sobre la incertidumbre social que gira en torno a la Gripe A y las consecuencias que puede generar en las decisiones sobre las polí- ticas de promoción de salud. Utilizamos conceptos y metáforas de la Teoría de la Elección Racional, entre ellas el “efecto ingratitud” y “el efecto desconfianza” y analizamos cómo estas pueden constituir obstáculos para la eficacia de las polí- ticas preventivas. Posteriormente, nos centramos en la asimetría informacional de la relación agente-principal y proponemos medidas para disminuir el “riesgo moral” que ocasionan. Por último, avanzamos algunas propuestas para el diseño de líneas y estrategias de actuación en políticas de promoción de salud.This article is a reflection on the social uncertainty caused by Influenza A and on the consequences that it can have on decision making in health promotion policies. We use concepts and metaphors of the Rational Choice Theory, among them, the “ingratitude effect” or the “distrust effect”, as we analyse how these can become obstacles for the efficiency of prevention policies. Then, we focus on the information asymmetry of the principal-agent relationship, and we propose measures to diminish the “moral risk” that they cause. We finish by advancing some proposals for designing lines and strategies of action in health promotion policies

    Estudi sobre les motivacions per a la pràctica de l’escalada en roca

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    Aquest article estudia les raons que porten els escaladors en roca a l’aire lliure a practicar aquest esport, analitzant les relacions existents entre aquestes motivacions i el gènere. Per a això es va emprar un qüestionari autoadministrat en una mostra de 146 escaladors (89 homes i 57 dones) de 18 a 54 anys (mitjana = 31,24 ± 6,96 anys). Els resultats van posar de manifest que les principals raons elegides pels escaladors eren intrínseques, destacant entre aquestes el contacte amb la natura, la recerca d’aventura, el repte personal i la diversió. Entre els motius menys assenyalats hi trobem la millora de la imatge, la competició i el reconeixement social. Per gènere, les escaladores van elegir en major grau la diversió i la millora de la imatge com a motius per escalar

    In silico logistic model for table olive related microorganisms as a function of sodium metabisulphite, cinnamaldehyde, pH, and Type of acidifying agent

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    A probabilistic/logistic model, based on binary data (growth/no growth), was used to assess the effects of sodium metabisulphite (SM) and cinnamaldehyde (CIN; 0-1000 mg/L) against the main microbial groups found in table olive environment [lactic acid bacteria (LAB), yeasts, and Enterobacteriaceae], according to pH (range 3.5-5.0), and type of acidifying agent (HCl or pyruvic acid). The inhibitory effect of SM depended on the pH while that of CIN was scarcely influenced by it (except for LAB). LAB were more sensitive to SM, while yeasts were to CIN. The use of pyruvic acid for correction of pH always produced a reduction (compared to HCl) of the inhibitory power of both preservatives. The in silico models for HCl showed that, at pH 4.0, and growth probability 0.01, the LAB population might be inhibited by the presence in the medium of 150 mg/L SM or 1000 mg/L CIN, while in the case of yeasts, 450 mg/L SM, or 150 mg/L CIN are required. No growth of Enterobacteriaceae was observed at this (or lower) pH level. The results obtained may contribute to the stabilization of non-thermally treated table olive packaging.This research has received funding from INTERACEITUNA (Organización Interprofesional de la Aceituna de Mesa, Spain) and the Junta de Andalucía. FNAL thanks to the Spanish Government and CSIC for his Ramón y Cajal postdoctoral research contract, while VR thanks the AgriFood Campus of International Excellence (ceiA3), Bank of Santander, Spanish Government and “Aloreña de Málaga” Olive Manufacturing Association for her pre-doctoral fellowship (training and formation program of Ph.D. in companies).Peer Reviewe

    Sensors Data Analysis in Supervisory Control and Data Acquisition (SCADA) Systems to Foresee Failures with an Undetermined Origin

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    This paper presents the design and implementation of a supervisory control and data acquisition (SCADA) system for automatic fault detection. The proposed system offers advantages in three areas: the prognostic capacity for preventive and predictive maintenance, improvement in the quality of the machined product and a reduction in breakdown times. The complementary technologies, the Industrial Internet of Things (IIoT) and various machine learning (ML) techniques, are employed with SCADA systems to obtain the objectives. The analysis of different data sources and the replacement of specific digital sensors with analog sensors improve the prognostic capacity for the detection of faults with an undetermined origin. Also presented is an anomaly detection algorithm to foresee failures and to recognize their occurrence even when they do not register as alarms or events. The improvement in machine availability after the implementation of the novel system guarantees the accomplishment of the proposed objectives.This work was supported partially by the Basque Government through project IT1207-19, and by the MCIU/MINECO through RTI2018-094902-B-C21/RTI2018-094902-B-C22 (MCIU/AEI/FEDER, UE). The authors would like to thank Intenance Company for its collaboration and help

    Wastewater Treatment by Advanced Oxidation Process and Their Worldwide Research Trends

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    Background: Water is a scarce resource and is considered a fundamental pillar of sustainable development. The modern development of society requires more and more drinking water. For this cleaner wastewater, treatments are key factors. Among those that exist, advanced oxidation processes are being researched as one of the sustainable solutions. The main objective of this manuscript is to show the scientific advances in this field. Methods: In this paper, a systematic analysis of all the existing scientific works was carried out to verify the evolution of this line of research. Results: It was observed that the three main countries researching this field are China, Spain, and the USA. Regarding the scientific collaboration between countries, three clusters were detected—one of Spain, one of China and the USA, and one of Italy and France. The publications are grouped around three types of water: industrial, urban, and drinking. Regarding the research, 15 clusters identified from the keywords analyzed the advanced oxidation process (alone or combined with biological oxidation) with the type of wastewater and the target pollutant, removal of which is intended. Finally, the most important scientific communities or clusters detected in terms of the number of published articles were those related to the elimination of pollutants of biological origin, such as bacteria, and of industrial nature, such as pesticides or pharmaceutical products
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