3,275 research outputs found

    Adaptive Comfort Models Applied to Existing Dwellings in Mediterranean Climate Considering Global Warming

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    Comfort analysis of existing naturally ventilated buildings located in mild climates, such as the ones in the Mediterranean zones, offer room for a reduction in the present and future energy consumption. Regarding Spain, most of the present building stock was built before energy standards were mandatory, let alone considerations about global warming or adaptive comfort. In this context, this research aims at assessing adaptive thermal comfort of inhabitants of extant apartments building in the South of Spain per EN 15251:2007 and ASHRAE 55-2013. The case study is statistically representative housing built in 1973. On-site monitoring of comfort conditions and computer simulations for present conditions have been carried out, clarifying the degree of adaptive comfort at present time. After that, additional simulations for 2020, 2050, and 2080 are performed to check whether this dwelling will be able to provide comfort considering a change in climate conditions. As a result, the study concludes that levels of adaptive comfort can be considered satisfactory at present time in these dwellings, but not in the future, when discomfort associated with hot conditions will be recurrent. These results provide a hint to foresee how extant dwellings, and also dwellers, should adapt to a change in environmental conditions

    Interpretation of column experiments of transport of solutes undergoing an irreversible bimolecular reaction using a continuum approximation

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    We provide a quantitative interpretation of the column experiment reported by Gramling et al. (2002). The experiment involves advection‐dominated transport in porous media of three dissolved species, i.e., two reactants undergoing a fast irreversible reaction and the resulting product. The authors found that their observations could not be properly fitted with a model based on an advection‐dispersion‐reaction equation (ADRE) assuming the reaction was instantaneous, the actual measured total reaction product being lower than predictions for all times. The data have been recently well reproduced by Edery et al. (2009, 2010) by means of a particle tracking approach in a continuous time random walk framework. These and other authors have questioned the use of partial differential equation (PDE)–based approaches to quantify reactive transport because of the difficulty in capturing local‐scale mixing and reaction. We take precisely this approach and interpret the experiments mentioned by means of a continuum‐scale model based on the ADRE. Our approach differs from previous modeling attempts in that we imbue effects of incomplete mixing at the pore scale in a time‐dependent kinetic reaction term and show that this model allows quantitative interpretation of the experiments in terms of both reaction product profiles and time‐dependent global production rate. The time dependence of the kinetic term presented accounts for the progressive effects of incomplete mixing due to pore‐scale rate‐limited mass transfer, and follows a power law, which is consistent with the compilation of existing experiments reported by Haggerty et al. (2004). Our interpretation can form the basis for further research to assess the potential use of PDE approaches for the interpretation of reactive transport problems in moderately heterogeneous medi

    Reaction rates and effective parameters in stratified aquifers

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    Chemical species are advected by water and undergo mixing processes due to effects of local diffusion and/or dispersion. In turn, mixing causes reactions to take place so that the system can locally equilibrate. In general, a multicomponent reactive transport problem is described through a system of coupled non-linear partial differential equations. Under instantaneous chemical equilibrium, a complex geochemical problem can be highly simplified by fully defining the system in terms of conservative quantities, termed master species or components, and the space–time distribution of reaction rates. We investigate the parameters controlling reaction rates in a heterogeneous aquifer at short distances from the source. Hydraulic conductivity at this scale is modeled as a random process with highly anisotropic correlation structure. In the limit for very large horizontal integral scales, the medium can be considered as stratified. Upon modeling transport by means of an ADE (Advection Dispersion Equation), we derive closed-form analytical solutions for statistical moments of reaction rates for the particular case of negligible transverse dispersion. This allows obtaining an expression for an effective hydraulic conductivity, , as a representative parameter describing the mean behavior of the reactive system. The resulting is significantly smaller than the effective conductivity representative of the flow problem. Finally, we analyze numerically the effect of accounting for transverse local dispersion. We show that transverse dispersion causes no variation in the distribution of (ensemble) moments of local reaction rates at very short travel times, while it becomes the dominant effect for intermediate to large travel times

    Papiroflexia matemática

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    El aprendizaje del alumnado es significativo cuando son ellos quienes construyen su aprendizaje. La papiroflexia puede ser una herramienta muy útil a la hora de guiar al alumnado hacia este tipo de aprendizaje, sobre todo a edades tan tempranas como es el primer ciclo de la educación secundaria obligatoria. La introducción de la papiroflexia como parte de la metodología docente implica que el alumnado estudiará los conceptos geométricos a través de sus propias construcciones y no a partir de conceptos abstractos expuestos de manera magistral en una pizarra. Presentamos en este póster 5 actividades de papiroflexia matemática adaptadas al primer ciclo de E.S.O

    Diseño de un algoritmo de búsqueda tabú para la minimización del desperdicio de espacio en almacenes de empresas comercializadoras de tuberías

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    Durante el presente proyecto de fin de carrera se plantea el desarrollo de un algoritmo metaheurístico el cual brinde una buena solución para el problema planteado. Esto se debe a diversos factores como la ubicación del almacén donde se colocaran los productos (rumas o estanterías) y los criterios en base a los cuales se apilaran los productos (tamaño, forma y peso) que deben considerarse al momento de realizar el almacenamiento de productos terminados. Además, como se mencionó anteriormente, estos factores se vuelven más complejos cuando se trata de tuberías, debido a que estas poseen una forma circular. Finalmente, este algoritmo no tiene como objetivo resolver el problema de forma exacta dada la complejidad de tiempo y recursos que presenta; sin embargo, permite obtener una buena solución que pueda cubrir con las necesidades de almacenamiento y que pueda ser ejecutada en un tiempo comprensible a las necesidades del negocio.Tesi

    Estimación de densidad poblacional de aves playeras y congregatorias mediante algoritmos de visión artificial

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    RESUMEN : En este proyecto de investigación se propone una metodología de bajo costo computacional, para la estimación de densidad de aves playeras y congregatorias en imágenes y vídeo, a través de algoritmos de visión artificial con un bajo costo computacional. El sistema se compone de tres metodologías: análisis de imagen, estabilización de vídeo y análisis de vídeo. En la metodología de análisis de imagen, se estima el número de aves a través de un algoritmo de regiones de interés, un clasificador basado en redes neuronales convolucionales, y la selección de un umbral para la detección. En la metodología de estabilización de vídeo, se propone una compensación de movimiento a través de la estimación, modelamiento y estabilización de movimiento en la grabación, para su posterior corrección. Por último, en la metodología de análisis de vídeo, se estima el número de aves a través de un algoritmo de substracción de fondo utilizando la mediana temporal de los frames que componen la grabación. Adicionalmente, se desarrolló una herramienta de software de código abierto y libre distribución, para estimar la densidad poblacional de aves playeras y congregatorias en imágenes y vídeo, usando las metodologías descritas previamente

    Attitudes of dental implantologists in Spain to prescribing antibiotics, analgesics and anti-inflammatories in healthy patients

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    The implantologists frequently prescribe antibiotics, analgesics and anti-inflammatories in dental implant surgery. The aims of this study were to evaluate the attitudes of implantologists in Murcia (Spain) to prescribing antibiotics, analgesics and anti-inflammatories in healthy patients during different implant dentistry procedures, and to see how these are influenced by individual dentist?s academic level, professional experience, and ongoing training (attending courses or reading scientific literature on medication use) This cross-sectional study included a total of 200 implantologists from the Murcia area (Spain), who each completed a two-page questionnaire consisting of 26 questions. The implant procedure in which most dentists (n=97) prescribed antibiotics was multiple implant surgery with flap raising, in which 55.6% of these 97 respondents used a prophylactic antibiotic regime for 7 days after implant placement. All subjects (n=200) prescribed analgesics for eight out of the eleven procedures included in the survey and anti-inflammatories in six. Dentists with higher academic levels or longer professional experience prescribed more antibiotics, but those who underwent continuous training (attending courses or reading scientific literature) reduced antibiotic prescription. Dentists often prescribed antibiotics, analgesics and anti-inflammatories in almost all implant procedures in healthy patients, but ongoing training reduced the frequency of antibiotic prescription in some procedures

    Topological Progression in Proliferating Epithelia Is Driven by a Unique Variation in Polygon Distribution

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    Morphogenesis is consequence of lots of small coordinated variations that occur during development. In proliferating stages, tissue growth is coupled to changes in shape and organization. A number of studies have analyzed the topological properties of proliferating epithelia using the Drosophila wing disc as a model. These works are based in the existence of a fixed distribution of these epithelial cells according to their number of sides. Cell division, cell rearrangements or a combination of both mechanisms have been proposed to be responsible for this polygonal assembling. Here, we have used different system biology methods to compare images from two close proliferative stages that present high morphological similarity. This approach enables us to search for traces of epithelial organization. First, we show that geometrical and network characteristics of individual cells are mainly dependent on their number of sides. Second, we find a significant divergence between the distribution of polygons in epithelia from mid-third instar larva versus early prepupa. We show that this alteration propagates into changes in epithelial organization. Remarkably, only the variation in polygon distribution driven by morphogenesis leads to progression in epithelial organization. In addition, we identify the relevant features that characterize these rearrangements. Our results reveal signs of epithelial homogenization during the growing phase, before the planar cell polarity pathway leads to the hexagonal packing of the epithelium during pupal stages.LME is supported by the Miguel Servet (Instituto Carlos III) program that also funded the work. LME and DSG are funded by the Spanish Ministry of Science (BFU2011-25734). AS is funded by the Consejería de Innovación, Ciencia y Empresa of the Junta de Andalucía.Peer Reviewe

    Zigzag equilibrium structure in monatomic wires

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    We have applied first-principles density-functional calculations to the study of the energetics, and the elastic and electronic properties of monatomic wires of Au, Cu, K, and Ca in linear and a planar-zigzag geometries. For Cu and Au wires, the zigzag distortion is favorable even when the linear wire is stretched, but this is not observed for K and Ca wires. In all the cases, the equilibrium structure is an equilateral zigzag (bond angle of 60o^{\rm o}). Only in the case of Au, the zigzag geometry can also be stabilized for an intermediate bond angle of 131o^{\rm o}. The relationship between the bond and wire lengths is qualitatively different for the metallic (Au, Cu and, K) and semiconducting (Ca) wires.Comment: 4 pages with 3 postscript figures. To appear in Surf. Science (proceedings of the European Conference on Surface Science, ECOSS-19, Madrid Sept. 2000

    Reliability of IBM’s Public Quantum Computers

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    One of the challenges of the current ecosystem of quantum computers (QC) is the stabilization of the coherence associated with the entanglement of the states of their inner qubits. In this empirical study, we monitor the reliability of IBM’s public-access QCs network on a daily basis. Each of these state-of-the-art machines has a totally different qubit association, and this entails that for a given (same) input program, they may output a different set of probabilities for the assembly of results (including both the right and the wrong ones). Although we focus on the computing structure provided by the “Big Blue” company, our survey can be easily transferred to other currently available quantum mainframes. In more detail, we probe these quantum processors with an ad hoc designed computationally demanding quaternary search algorithm. As stated, this quantum program is executed every 24 hours (for nearly 100 days) and its goal is to put to the limit the operational capacity of this novel and genuine type of equipment. Next, we perform a comparative analysis of the obtained results according to the singularities of each computer and over the total number of executions. In addition, we subsequently apply (for 50 days) an improvement filtering to perform noise mitigation on the results obtained proposed by IBM. The Yorktown 5-qubit computer reaches noise filtering of up to 33% in one day, that is, a 90% confidence level is reached in the expected results. From our continuous and long-term tests, we derive that room still exists regarding the improvement of quantum calculators in order to guarantee enough confidence in the returned outcomes
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