Elastic, dielectric and electromechanical properties of (Bi0.5Na0.5)TiO3-BaTiO3 piezoceramics at the morphotropic phase boundary region

A systematic study of the functional properties of the (1-x)(Bi0.5Na0.5)TiO3–xBaTiO3 (BNT-xBT) piezoceramic system for 0.05 = x = 0.07 is performed. The samples are obtained through the conventional solid-state route. The expected microstructure for these compounds, with no significant dependence on the composition, is verified by field-emission scanning electron microscopy. The morphotropic phase boundary (MPB) is detected for x = 0.06–0.07 by means of the Rietveld analysis of X-ray diffraction data. The dielectric spectra show a frequency-independent, completely diffuse phase transition with a composition-dependent diffusivity coefficient. The depolarization temperature is effectively evaluated from pyroelectric measurements, the value being strongly dependent on the composition. A significant contribution of the extrinsic effect to elastic, dielectric and electromechanical properties is revealed for MPB BNT-xBT. The Bi3+ substitution by Ba2+ leads to the formation of A-site vacancies, which give rise to the enhancement of domain wall motion, as occurs in other perovskite-type piezoelectrics. Good functional properties are achieved for x = 0.07 (d33 = 180 pC/N), which are similar or even better than those obtained by complex synthesis routes. This system exhibits a remarkable stability in the permittivity that has hitherto not been reported. This fact may open the way for BNT-BT compositions to be used in specific applications in which lead-free piezoceramics have previously been employed with little success, e.g. in high power devices.Postprint (author's final draft

RANS simulations of wind flow at the Bolund experiment

As part of their development, the predictions of numerical wind flow models must be compared with measurements in order to estimate the uncertainty related to their use. Of course, the most rigorous such comparison is under blind conditions. The following paper includes a detailed description of three different wind flow models, all based on a Reynolds-averaged Navier-Stokes approach and two-equation k-ε closure, that were tested as part of the Bolund blind comparison (itself based on the Bolund experiment which measured the wind around a small coastal island). The models are evaluated in terms of predicted normalized wind speed and turbulent kinetic energy at 2 m and 5 m above ground level for a westerly wind direction. Results show that all models predict the mean velocity reasonably well; however accurate prediction of the turbulent kinetic energy remains achallenge

Desarrollo de un programa de mentorías de matemáticas para los alumnos de grado de la Facultad de Ciencias Económicas y Empresariales

Programa de mentorías por parte de alumnos de cursos superiores a alumnos de primer curso del Grado en Economía en asignaturas de matemáticas que les permita mejorar su motivación y los resultados logrados

Mudflow Modeling in the Copiapó Basin, Chile

[EN] Extreme precipitation events that occurred between March 24 and March 26 of 2015 in the region of the Atacama Desert (26-29°S) left around 30 000 victims, being one of the biggest events over the past 50 years, with total a cost of reconstruction of about 1.5 billion dollars. The mudflows which increased during the flashflood inundated much of the city of Copiapó and Tierra Amarilla. This manuscript aims to model the mudflow of March 2015 in the Río Copiapó, specifically in the towns of Copiapó and Tierra Amarilla. The modeling process is performed using the Rapid Mass Movement Simulation Model (RAMMS) that allows modeling the dynamics of the mudflow in two dimensions, only using the topographic features of the modeling domain. Calibration of the model was carried out successfully using data from inundation heights captured around the city after the 2015 event. A detailed analysis of the hydrometeorological event is carried out using satellite images obtained from Multi-satellite Precipitation Analysis (TMPA), and pluviometric and hydrographic data available in the Copiapó River basin. The simulation of the flood is reproduced with maps of inundation heights associated with two modeling scenarios. The maximum flood heights are ultimately used for developing risk maps at both sites. According to our results, the RAMMS model is an appropriate tool for modeling mudflow and mapping flood risk to improve hydrological risk management in arid and semiarid basins of Chile[ES] Los eventos extremos de precipitación intensa que se produjeron entre el 24 y 26 de marzo de 2015 en la región del Desierto de Atacama (26-29°S), en el Norte de Chile, dejaron alrededor de 30 000 damnificados, siendo uno de los eventos de mayores magnitudes de los últimos 50 años, y que tuvo un costo de reconstrucción de alrededor de $1.5 billones de dólares. Los flujos de detritos que se incrementaron durante la crecida inundaron gran parte de las ciudades de Copiapó y Tierra Amarilla. Este manuscrito tiene por objetivo modelar la crecida aluvional de marzo de 2015 en la cuenca del Río Copiapó, específicamente en las localidades de Copiapó y Tierra Amarilla. La modelación se lleva a cabo utilizando el modelo Rapid Mass Movement Simulation (RAMMS) que permite modelar la dinámica de la crecida aluvional en dos dimensiones, utilizando las características topográficas de los dominios de modelación. La calibración del modelo fue llevada a cabo satisfactoriamente utilizando datos de alturas capturados en terreno después de la crecida del año 2015. Un análisis detallado del evento hidrometeorológico es llevado a cabo utilizando imágenes satelitales obtenidas desde Multi-satellite Precipitation Analysis (TMPA), así como datos pluviométricos e hidrográficos disponibles en la cuenca del Río Copiapó. La simulación de la crecida es reproducida con mapas de alturas de inundación asociados a dos escenarios de modelación. Las alturas máximas de inundación son finalmente utilizadas para el desarrollo de mapas de riesgos en ambas localidades. De acuerdo a nuestros resultados, el modelo RAMMS es una herramienta apropiada para modelar crecidas aluvionales y elaborar mapas de riesgos de inundación para mejorar la gestión de riesgos hidrológicos en cuencas áridas y semiáridas de Chile.Los autores de este manuscrito agradecen el financiamiento proporcionado por La Fundación Centro Nacional del Medio Ambiente de Chile (CENMA) para llevar a cabo este estudio. Adicionalmente, se agradece la contribución de datos de alturas de inundación proporcionados por Tatiana Izquierdo (académica de la Universidad de Atacama) los cuales permitieron la calibración del modelo RAMMS.Valdés-Pineda, R.; Valdés, JB.; García-Chevesich, P. (2017). Modelación de Crecidas Aluvionales en la Cuenca del Río Copiapó, Chile. Ingeniería del Agua. 21(2):135-152. doi:10.4995/ia.2017.7366.SWORD135152212Abrams, M. 2000. The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER): data products for the high spatial resolution imager on NASA's Terra platform. International Journal of Remote sensing, 21(5), 847-859. https://doi.org/10.1080/014311600210326Barrett, B. S., Campos, D. A., Veloso, J. V., Rondanelli, R. 2016. Extreme temperature and precipitation events in March 2015 in central and northern Chile. Journal of Geophysical Research: Atmospheres, 121(9): 4563-4580. https://doi.org/10.1002/2016jd024835Bontemps, S., Defourny, P., Bogaert, E. V., Arino, O., Kalogirou, V., Perez, J. R. 2011. GLOBCOVER 2009-Products description and validation report.Bozkurt, D., Rondanelli, R., Garreaud, R., Arriagada, A. 2016. Impact of warmer eastern tropical Pacific SST on the March 2015 Atacama floods. Monthly Weather Review, 144(11), 4441-4460. https://doi.org/10.1175/MWR-D-16-0041.1Christen, M., Bartelt, P., Kowalski, J., Stoffel, L. 2008. Calculation of dense snow avalanches in three-dimensional terrain with the numerical simulation program RAMMS. In Proceedings Whistler 2008 International Snow Science Workshop, September 21-27, 2008 (p. 709).Christen, M., Kowalski, J., Bartelt, P. 2010. RAMMS: numerical simulation of dense snow avalanches in three-dimensional terrain. Cold Regions Science and Technology, 63(1), 1-14. https://doi.org/10.1016/j.coldregions.2010.04.005Ferrando, R., Fuentes, F., Coloma, F., Merino. 2015. Efectos Geológicos del Evento Meteorológico del 24 y 25 de marzo De 2015: Fotointerpretación y Reconocimiento en Terreno del Efecto de Aluviones e Inundaciones en las zonas de Tierra Amarilla y Nantoco: Zona de Inundación y zonas propuestas para Evacuación, Campamento y Acopio. SERNAGIOMIN.Izquierdo, T., Abad, M. Bernárdez, E. 2016. Catastrophic flooding caused by a mudflow in the urban area of Copiapó (Atacama Desert, northern Chile). International Conference on Urban Risks.MOP-DGA, C. I. 2004. Diagnóstico y clasificación de los cursos y cuerpos de agua según objetivo de calidad. Cuenca Quebrada de Tarapacá. Santiago, Chile.Naranjo, J. A., Olea-Encina, P. 2015. Descargas aluviales durante la tormenta del desierto de Atacama en marzo de 2015, Chile. SERNAGIOMIN.Pizarro-Tapia, R., Valdés-Pineda, R., Olivares, C., González, P. A. 2014. Development of Upstream Data-Input Models to Estimate Downstream Peak Flow in Two Mediterranean River Basins of Chile. Open Journal of Modern Hydrology, 4(4), 132-143. https://doi.org/10.4236/ojmh.2014.44013Quan, L. 2012. Dynamic numerical run-out modeling for quantitative landslide risk assessment. Thesis of University of Twente, ITC, 206:1-237.Raïmat, C., Riera, E., Graf, C., Luis-Fonseca, R., Fañanás, C., Hurlimann Ziegler, M. 2013. Experiencia de la aplicación de RAMMS para la modelización de flujo tras la aplicación de las soluciones flexibles VX en el barranc de Portainé. In VIII Simposio Nacional sobre Taludes y Laderas Inestables, 1131-1144. Centre Internacional de Mètodes Numèrics en Enginyeria (CIMNE).Tachikawa, T., Hato, M., Kaku, M., Iwasaki, A. 2011. Characteristics of ASTER GDEM version 2. In Geoscience and Remote Sensing Symposium (IGARSS), 2011 IEEE International, 3657-3660. https://doi.org/10.1109/IGARSS.2011.6050017Valdés-Pineda, R., Valdés, J. B., Diaz, H. F., Pizarro-Tapia, R. 2016. Analysis of spatio-temporal changes in annual and seasonal precipitation variability in South America-Chile and related ocean-atmosphere circulation patterns. International Journal of Climatology, 36(8), 2979-3001. https://doi.org/10.1002/joc.4532Valdés-Pineda, R., Cañón, J., Valdés, J. B. 2017. Multi-decadal 40-to 60-year cycles of precipitation variability in Chile (South America) and their relationship to the AMO and PDO signals. Journal of Hydrology. (In Press). http://doi.org/10.1016/j.jhydrol.2017.01.03

WEBSEIDF: A web-based system for the estimation of IDF curves in Central Chile

The lack of reliable continuous rainfall records can exacerbate the negative impact of extreme storm events. The inability to describe the continuous characteristics of rainfall from storm events increases the likelihood that the design of hydraulic structures will be inadequate. To mitigate extreme storm impacts and improve water governance at the catchment scale, it is vital to improve the availability of data and the array of tools used to model and forecast hydrological processes. In this paper, we describe and discuss the implementation of a web-based system for the estimation of intensity–duration–frequency (IDF) curves (WEBSEIDF) in Chile. The web platform was constructed using records from 47 pluviographic gauges available in central Chile (30–40° S), with at least 15 years of reliable records. IDF curves can be generated for durations ranging from 15 min to 24 h. In addition, the extrapolation of rainfall intensity from pluviograph to pluviometric gauges (i.e., 24-h rainfall accumulation) can be carried out using the storm index (SI) method. IDF curves can also be generated for any spatial location within central Chile using the ordinary Kriging method. These procedures allow the generation of numerical and graphical displays of IDF curves, for any selected spatial location, and for any combination of probability distribution function (PDF), parameter estimation method, and type of IDF model. One of the major advantages of WEBSEIDF is the flexibility of its database, which can be easily modified and saved to generate IDF curves under user-defined scenarios, that is, changing climate conditions. The implementation and validation of WEBSEIDF serves as a decision support system, providing an important tool for improving the ability of the Chilean government to mitigate the impact of extreme hydrologic events in central Chile. The system is freely available for students, researchers, and other relevant professionals, to improve technical decisions of public and private institutions

Displays and Photonics Application Group activities

Displays and Photonics Application Group (GDAF) is devoted to design and development of passive and active devices and sensors for their applications in WDM networks, CWDM, POP, and RF over fiber networks using different technologies such as optical fibers, liquid crystals, and integrated optics. The group is also very active in modeling, electrooptical characterization, and addressing electronics of LCDs. In this article we are going to describe the main activities carried out in the group.Publicad

Caracterización físico-mecánica de la madera de Abies alba Miller procedente del pirineo español mediante probetas libres de defectos

This study provides up-to-date, representative values of the physical and mechanical properties of silver fir wood from the Spanish Pyrenees for comparison with other provenances and timber species. Tests were conducted with clear specimens obtained throughout the tree stem and properties were determined following the UNE standards of the corresponding tests. The wood was found to be light (ρ = 0.48 g/cm3), soft (H = 1.71 mm-1) and moderately stable (v = 39.43%). Its bending strength (MOR = 78.70 N/ mm2) is low and its compressive strength (MCS = 44.88 N/mm2) is average. Impact behaviour is average (K = 41.46 N/mm) and cleavage behaviour (C = 19.92 N/ mm) is low, as are tangential and radial tension perpendicular to the grain (1.71 and 1.68 N/mm2). The differences obtained in comparison with other provenances of this species may be the result of the location of the silver firs at the edge of their geographical distribution and thus the specific conditions of the site have a greater effect on the wood properties.El objetivo de esta investigación es proporcionar valores actualizados y representativos de las propiedades físicas y mecánicas de la madera de abeto del Pirineo español para permitir su comparación con otras procedencias y especies maderables. Los ensayos se realizaron a partir de probetas libres de defectos obtenidas a lo largo del fuste y se determinaron las propiedades de acuerdo a las normas UNE de los ensayos correspondientes. Se concluye que la madera es ligera (ρ = 0,48 g/cm3), blanda (H = 1,71 mm-1) y moderadamente nerviosa (v = 39,43%). La resistencia a flexión (MOR = 78,70 N/mm2) es baja y a compresión (MCS = 44,88 N/ mm2) media. Presenta un comportamiento al impacto medio (K = 41,46 N/mm) y bajo a hienda (C = 19,92 N/mm), tracción perpendicular tangencial y radial (1,71 y 1,68 N/mm2). Las diferencias obtenidas con respecto a otras procedencias de esta especie pueden deberse a que el abeto se encuentra en su límite de distribución geográfica y en consecuencia las condiciones específicas de sitio tienen mayor influencia en las propiedades de la madera

Distributional and reproductive aspects of the bigeye thresher shark (Alopias superciliosus) in the Atlantic ocean

Captura asociada a la pesquería de palangre de superficie dirigida a pez espadaThe bigeye thresher shark, Alopias supercilious is sometimes caught as bycatch in pelagic longline fisheries targeting tunas and swordfish in the Atlantic Ocean. As part of an ongoing cooperative program for fisheries and biological data collection, fishery observer data from various fishing nations and projects were compiled and analyzed. Those data sets include information on geographic location of the observations, as well as size, sex and in some cases maturity stage. A total of 4371 bigeye threshers were recorded throughout the Atlantic Ocean between 1992 and 2013, with the sizes ranging from 70 to 305 cm FL (fork length). Considerable variability was observed in the catchat- size, with particular emphasis on the tropical region where the mean sizes tended to be smaller than in the other regions. The expected distribution of juvenile and adult specimens also showed considerable variability, and the sex-ratios varied between regions and size classes. Maturity ogives were fitted to data from 642 specimens, with the median sizes at maturity estimated at 208.6 cm FL (corresponding to 349.1 cm TL) for females and 159.2 cm FL (corresponding to 269.8 cm TL) for males. In addition, a segmented regression model (SRM) was used for males, and two breakpoints (Bk1: 122.5cm FL, Bk2: 173.3cm FL) estimated, identifying transitions between the three different maturity stages for male sharks (immature, maturing and mature). Only a few pregnant females were recorded, always with the presence of two embryos (one per uterus), and were distributed predominantly in the tropical northeast Atlantic closer the African continent, and in the southwest region, with those regions possibly serving as nursery areas for this species. These reproductive parameters, and especially the estimated median sizes at maturity and low fecundity, highlight the vulnerability of this species, reinforcing that the bigeye thresher tends to mature at a larger size than the other species of the Alopiidae family. The biological and distributional patterns presented can help managers adopt more informed and efficient conservation measures for this species.En prensa0,000

Paediatricians provide higher quality care to children and adolescents in primary care: A systematic review

Aim: The number of primary care paediatricians is decreasing in Europe without a justifiable reason. We aimed to compare the clinical practice of paediatricians and family doctors attending children and adolescents in primary care. Methods: MEDLINE, Embase, CENTRAL, TRIP and Google Scholar were searched from December 2008 to February 2018. No language or study design restrictions were applied. Three reviewers assessed eligibility of the studies. Seven pairs of reviewers performed the data extraction and assessed the methodological quality independently. Discrepancies were resolved by consensus. Results: Fifty-four, out of 1150 studies preselected, were included. We found that paediatricians show more appropriate pharmacology prescription patterns for the illness being treated; they achieve higher vaccination rates and have better knowledge of vaccines and fewer doubts about vaccine safety; their knowledge and implementation of different screening tests are better; they prescribe psychoactive drugs more cautiously and more in line with current practice guidelines; their evaluation and treatment of obesity and lipid disorders follow criteria more consistently with current clinical practice guidelines; and they perform fewer diagnostic test, show a more suitable use of the test and request fewer referrals to specialists. Conclusion: According to published data, in developed countries, paediatricians provide higher quality care to children than family doctors

Recovery of Meteorological Data for the Observatory of A Guarda, Spain

We herein describe the recovery of a series of data on temperature, humidity, precipitation, evaporation, wind, and local weather conditions from documentary sources obtained from the Jesuit observatory of A Guarda (Galicia, Spain) for the period 1881–1896. The data were digitized and made available in accessible electronic formats. Comparisons were made with present-day meteorological data obtained from two nearby stations. We further believe that the discovery of some new complementary documentary sources made during the present research could be a basis for future data recovery efforts. Among these new results, early ozone data from the period are of outstanding importance to meteorologists