509 research outputs found

    Analysis of the power balance In the cells of a multilevel cascaded H-Bridge converter

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    Multilevel cascaded H-Bridge converters (CHB) have been presented as a good solution for high power applications. In this way, several control and modulation techniques have been proposed for this power converter topology. In this paper the steady state power balance in the cells of the single phase two cell CHB is studied. The capability to be supplied with active power from the grid or to deliver active power to the grid in each cell is analyzed according to the dc-link voltages and the desired ac output voltage value. Limits of the maximum and minimum input active power for stable operation of the CHB are addressed. Simulation results are shown to validate the presented analysis

    Design of the Front End Electronics for the Infrared Camera of JEM-EUSO, and manufacturing and verification of the prototype model

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    The Japanese Experiment Module (JEM) Extreme Universe Space Observatory (EUSO) will be launched and attached to the Japanese module of the International Space Station (ISS). Its aim is to observe UV photon tracks produced by ultra-high energy cosmic rays developing in the atmosphere and producing extensive air showers. The key element of the instrument is a very wide-field, very fast, large-lense telescope that can detect extreme energy particles with energy above 101910^{19} eV. The Atmospheric Monitoring System (AMS), comprising, among others, the Infrared Camera (IRCAM), which is the Spanish contribution, plays a fundamental role in the understanding of the atmospheric conditions in the Field of View (FoV) of the telescope. It is used to detect the temperature of clouds and to obtain the cloud coverage and cloud top altitude during the observation period of the JEM-EUSO main instrument. SENER is responsible for the preliminary design of the Front End Electronics (FEE) of the Infrared Camera, based on an uncooled microbolometer, and the manufacturing and verification of the prototype model. This paper describes the flight design drivers and key factors to achieve the target features, namely, detector biasing with electrical noise better than 100μ100 \muV from 11 Hz to 1010 MHz, temperature control of the microbolometer, from 1010^{\circ}C to 4040^{\circ}C with stability better than 1010 mK over 4.84.8 hours, low noise high bandwidth amplifier adaptation of the microbolometer output to differential input before analog to digital conversion, housekeeping generation, microbolometer control, and image accumulation for noise reduction

    Implicaciones del filtrado de calidad del índice de vegetación EVI para el seguimiento funcional de ecosistemas

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    Revista oficial de la Asociación Española de Teledetección[EN] The use of MODIS (Moderate Resolution Imaging Spectroradiometer) images for ecosystem monitoring is currently widespread both in research and management. Vegetation indexes (VIs), such as NDVI (Normalized Difference Vegetation Index) and EVI (Enhanced Vegetation Index), are broadly extended for monitoring ecosystem functioning. These indexes are linear estimators of the fraction of photosynthetically active radiation intercepted by vegetation (fAPAR), the main control of net primary production. However, VIs are subject to errors. To handle such errors, the MOD13Q1 VI product includes a Quality Assessment (QA) layer with information about pixel quality. This QA layer represents a great advantage for final users, allowing filtering of pixels with VI values influenced by aerosols, clouds, snow, or shadows. However, the use of homogeneous filtering criteria throughout a heterogeneous region may cause the systematic loss of information in particular areas or times of the year. In this paper, we assessed the effect of different filtering criteria on spatiotemporal data of EVI for the period 2001-2010 in the Iberian Southeast. Our results showed no effect of filtering on EVI availability and magnitude values in low altitudes, but strong and significant differences in the mountains depending on the filter applied: aerosol, shadows or snow filters. Such effects of filtering on the EVI revealed that monitoring programs in these regions should include a filtering step before exploring for abrupt changes or longterm trends in the EVI time series.[ES] El seguimiento de los ecosistemas con imágenes procedentes del sensor MODIS (Moderate Resolution Imaging Spectroradiometer, espectroradiómetro de imágenes de resolución media) está actualmente muy extendido tanto en tareas de investigación como de gestión. Los índices de vegetación NDVI (Normalized Difference Vegetation Index, índice de vegetación de la diferencia normalizada) y EVI (Enhanced Vegetation Index, índice de vegetación mejorado) son ampliamente usados para la caracterización del funcionamiento ecosistémico. Ambos índices se emplean como estimadores lineales de la fracción de radiación fotosintéticamente activa interceptada por la vegetación (fAPAR), el principal control de la producción primaria. A pesar de sus ventajas, las imágenes de índices de vegetación no están libres de errores. El producto índices de vegetación MOD13Q1 proporciona una capa QA (Quality assessment, evaluación de la calidad) que informa sobre la calidad asociada a cada píxel. Esta información representa una gran ventaja para el usuario, al permitir filtrar aquellos datos que puedan inducir a errores al verse alterados por la presencia de aerosoles, nubes, nieve o sombras. Sin embargo, la realización de un filtrado homogéneo a lo largo de una gran región puede ocasionar la pérdida sistemática de información en determinadas zonas o épocas del año, introduciendo así un sesgo espacial o en la serie temporal. Esta situación puede ser especialmente crítica en regiones con alta heterogeneidad ambiental, como el Sureste Ibérico. En este trabajo evaluamos el efecto que el filtrado de calidad tiene sobre la información espacial y temporal de la base de datos del EVI en el periodo 2001-2010. Los resultados, expresados en porcentaje de información perdida (filtrada) y como efecto de estas pérdidas sobre los valores del EVI, indican que mientras que las áreas de menor altitud no se ven afectadas por el filtrado, las regiones de alta montaña muestran variaciones significativas en sus valores del EVI cuando son filtrados por aerosoles, sombras o la presencia de hielo o nieve. Esto pone de manifiesto la importancia del establecimiento de un protocolo para el procesamiento de la información que considere las características espaciales y temporales de los datos a filtrar.Este trabajo ha sido financiado por el Ministerio de Innovación y Ciencia (Proyecto CGL2010- 22314), la Junta de Andalucía (Proyecto SEGALERT, P09-RNM-5048) y el Centro Andaluz para la Evaluación y Seguimiento del Cambio Global (CAESCG) (Proyecto GLOCHARID).Reyes-Díez, A.; Alcaraz-Segura, D.; Cabello-Piñar, J. (2015). Implications of quality filtering of Enhanced Vegetation Index (EVI) for ecosystem functioning monitoring. Revista de Teledetección. (43):11-30. https://doi.org/10.4995/raet.2015.3316SWORD11304

    Theorizing the principles of sustainable production in the context of circular economy and industry 4.0

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    The concept of Sustainable Production is evolving with changes triggered by the emergence of new economic and industrial models such as Circular Economy and Industry 4.0. However, most studies that currently link these concepts are based on the principles of Sustainable Production defined 20 years ago. Therefore, the primary aim of this study is to redefine the principles that should govern Sustainable Production operations in the tran- sition towards a Circular Economy and smart industry models. To this end, an initial proposal of 11 principles was shared with 11 world-class experts (academics and practitioners) and a consensus proposal was sought through a Delphi Panel. Ten principles emerged from this study, which were evaluated by experts according to criteria of significance, parsimony, semantic consistency and empirical adequacy. Additionally, to study the rela- tionships between the ten principles, the Interpretative Structural Model (ISM) technique was applied. The ISM technique identified which principles are independent of or dependent on each other and established relation- ships between the principles. The findings suggest that Principle 5 (“Prioritize employees' well-being”), Principle 6 (“Enhance management commitment to sustainability”), Principle 9 (“Measure and optimize sustainable pro- cesses”) and Principle 10 (“Boost the use of sustainable technologies”) help to establish an ideal context to enhance the development of the rest of the principles that characterize Sustainable Production. The presentation of the ten principles opens new possibilities for researchers while helping managers to better understand sustainability in terms of production and, therefore contribute to achieving SDG 12

    Theorizing the principles of sustainable production in the context of Circular Economy and Industry 4.0

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    The concept of Sustainable Production is evolving with changes triggered by the emergence of new economic and industrial models such as Circular Economy and Industry 4.0. However, most studies that currently link these concepts are based on the principles of Sustainable Production defined 20 years ago. Therefore, the primary aim of this study is to redefine the principles that should govern Sustainable Production operations in the tran-sition towards a Circular Economy and smart industry models. To this end, an initial proposal of 11 principles was shared with 11 world-class experts (academics and practitioners) and a consensus proposal was sought through a Delphi Panel. Ten principles emerged from this study, which were evaluated by experts according to criteria of significance, parsimony, semantic consistency and empirical adequacy. Additionally, to study the rela-tionships between the ten principles, the Interpretative Structural Model (ISM) technique was applied. The ISM technique identified which principles are independent of or dependent on each other and established relation-ships between the principles. The findings suggest that Principle 5 ("Prioritize employees' well-being"), Principle 6 ("Enhance management commitment to sustainability"), Principle 9 ("Measure and optimize sustainable pro-cesses") and Principle 10 ("Boost the use of sustainable technologies") help to establish an ideal context to enhance the development of the rest of the principles that characterize Sustainable Production. The presentation of the ten principles opens new possibilities for researchers while helping managers to better understand sustainability in terms of production and, therefore contribute to achieving SDG 12

    Downscaling ECMWF seasonal precipitation forecasts in Europe using the RCA model

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    The operational performance and usefulness of regional climate models at seasonal time scales are assessed by downscaling an ensemble of global seasonal forecasts. The Rossby Centre RCA regional model was applied to downscale a five-member ensemble from the ECMWF System3 global model in the European Atlantic domain for the period 1981–2001. One month lead time global and regional precipitation predictions were compared over Europe—and particularly over Spain—focusing the study in SON (autumn) dry events. A robust tercile-based probabilistic validation approach was applied to compare the forecasts from global and regional models, obtaining significant skill in both cases, but over a wider area for the later. Finally, we also analyse the performance of a mixed ensemble combining both forecasts

    Assessing the skill of precipitation and temperature seasonal forecasts in Spain: windows of opportunity related to ENSO events

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    1. The skill of state-of-the-art operational seasonal forecast models in extratropical latitudes is assessed using a multimodel ensemble from the Development of a European Multimodel Ensemble System for Seasonalto- Interannual Prediction (DEMETER) project. In particular, probabilistic forecasts of surface precipitation and maximum temperature in Spain are analyzed using a high-resolution observation gridded dataset (Spain02). To this aim, a simple statistical test based on the observed and predicted tercile anomalies is used. First, the whole period 1960–2000 is considered and it is shown that the only significant skill is found for dry events in autumn. Then, the influence of ENSO events as a potential source of conditional predictability is studied and the validation to strong La Niña or El Niño periods is restricted. Skillful seasonal predictions are found in partial agreement with the observed teleconnections derived from the historical records. On the one hand, predictability is found in spring related to El Niño events for dry events over the south and the Mediterranean coast and for hot events in the southeast areas. In contrast, La Niña drives predictability in winter for dry events over the western part and for hot events in summer over the south and the Mediterranean coast. This study considers both the direct model outputs and the postprocessed predictions obtained using a statistical downscaling method based on analogs. In general, the use of the downscaling method outperforms the direct output for precipitation, whereas in the case of the temperature no improvement is obtained

    Embedded pitch adapters: a high-yield interconnection solution for strip sensors

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    A proposal to fabricate large area strip sensors with integrated, or embedded, pitch adapters is presented for the End-cap part of the Inner Tracker in the ATLAS experiment. To implement the embedded pitch adapters, a second metal layer is used in the sensor fabrication, for signal routing to the ASICs. Sensors with different embedded pitch adapters have been fabricated in order to optimize the design and technology. Inter-strip capacitance, noise, pick-up, cross-talk, signal efficiency, and fabrication yield have been taken into account in their design and fabrication. Inter-strip capacitance tests taking into account all channel neighbors reveal the important differences between the various designs considered. These tests have been correlated with noise figures obtained in full assembled modules, showing that the tests performed on the bare sensors are a valid tool to estimate the final noise in the full module. The full modules have been subjected to test beam experiments in order to evaluate the incidence of cross-talk, pick-up, and signal loss. The detailed analysis shows no indication of cross-talk or pick-up as no additional hits can be observed in any channel not being hit by the beam above 170 mV threshold, and the signal in those channels is always below 1% of the signal recorded in the channel being hit, above 100 mV threshold. First results on irradiated mini-sensors with embedded pitch adapters do not show any change in the interstrip capacitance measurements with only the first neighbors connected

    The Spanish Infrared Camera onboard the EUSO-BALLOON (CNES) flight on August 24, 2014

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    The EUSO-Balloon (CNES) campaign was held during Summer 2014 with a launch on August 24. In the gondola, next to the Photo Detector Module (PDM), a completely isolated Infrared camera was allocated. Also, a helicopter which shooted flashers flew below the balloon. We have retrieved the Cloud Top Height (CTH) with the IR camera, and also the optical depth of the nonclear atmosphere have been inferred with two approaches: The first one is with the comparison of the brightness temperature of the cloud and the real temperature obtained after the pertinent corrections. The second one is by measuring the detected signal from the helicopter flashers by the IR Camera, considering the energy of the flashers and the location of the helicopter
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