446 research outputs found

    Colección de Estudios, Mediterráneo Económico

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    Increasing the Resolution and Spectral Range of Measured Direct Irradiance Spectra for PV Applications

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    The spectral distribution of the solar irradiance incident on photovoltaic (PV) modules is a key variable controlling their power production. It is required to properly simulate the production and performance of PV plants based on technologies with different spectral characteristics. Spectroradiometers can only sense the solar spectrum within a wavelength range that is usually too short compared to the actual spectral response of some PV technologies. In this work, a new methodology based on the Simple Model of the Atmospheric Radiative Transfer of Sunshine (SMARTS) spectral code is proposed to extend the spectral range of measured direct irradiance spectra and to increase the spectral resolution of such experimental measurements. Satisfactory results were obtained for both clear and hazy sky conditions at a radiometric station in southern Spain. This approach constitutes the starting point of a general methodology to obtain the instantaneous spectral irradiance incident on the plane of array of PV modules and its temporal variations, while evaluating the magnitude and variability of the abundance of atmospheric constituents with the most impact on surface irradiance, most particularly aerosols and water vaporThe Spanish Ministry of Economy, Industry, and Competitiveness [project PVCastSOIL Nº ENE2017-83790-C3-1-2-3-R],The European Regional Development FundThe project MAPVSpain, with reference PID2020-118239RJ-I00, financed by the Ministerio de Ciencia e InnovaciónThe European Regional Development FundRamón y Cajal contract (RYC2021-031958-I), funded by the Spanish Ministerio de Ciencia e Innovación MCIN/AEI/10.13039/501100011033The European Union “NextGenerationEU/PRTRANID/FONDAP/15110019 “Solar Energy Research Center”, SERC-Chil

    Extremely fast and high Pb²⁺ removal capacity using a nanostructured hybrid material

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    Ultra-fast toxic metal removal using a hybrid and nanostructured vaterite-poly(ethyleneimine) (NV-PEI) is reported. Especially for Pb²⁺ , an extremely high and fast adsorption capacity without precedents is observed. Within a 3 min contact time (CT), 97-100% of Pb²⁺ contaminant in water samples at pH 6, with a large concentration range (from 2 to 1000 ppm) and using a dosage of 0.5 g NV-PEI per L, has been removed. The maximum adsorption capacity (q ) calculated for a 1500 ppm Pb initial concentration was 2762 mg of Pb²⁺ per g NV-PEI. In addition to the excellent Pb removal, this material is cheap, easy to synthesize, biocompatible, and biodegradable, which makes it superior to others reported to date and an attractive alternative for the treatment of industrial wastewaters

    Production of lactic acid from pasta wastes using a biorefinery approach

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    A total of 398 kt of pasta waste (PW), generated during the production process of pasta, were produced in 2021. Due to its chemical composition and practically zero cost, PW has already been studied as a raw material for the production of lactic acid (LA) through fermentations. The main objective of this article was to improve the economic viability of the process by replacing commercial enzymes, necessary for starch hydrolysis in PW, with raw enzymes also produced from wastes. Enzyme synthesis was achieved through solid-state fermentation (SsF) of wheat bran by Aspergillus awamori or Aspergillus oryzae at various moisture contents. The maximum amylase activity (52 U/g dry solid) was achieved after 2 days of fermentation with A. awamori at 60% of moisture content. After that, the enzymes were used to hydrolyse PW, reaching 76 g/L of total sugars, 65 g/L of glucose and a yield of 0.72 gglu/gds with the enzymes produced by A. awamori. Subsequently, the hydrolysate was fermented into LA using Bacillus coagulans A559, yielding 52 g/L and 49 g/L with and without yeast extract, respectively. Remarkably, compared to the process with commercial enzymes, a higher LA yield was reached when enzymes produced by SsF were added (0.80 gLA/gglu). Furthermore, the productivities between the two processes were similar (around 3.9 g/L/h) which highlights that yeast extract is not necessary when using enzymes produced by SsF

    The impact of climate change on air conditioning needs in Andalusia at detailed scales

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    Ce travail analyse les variations spatiotemporelles subies par les besoins de climatisation (chauffage et réfrigération) en Andalousie dans le contexte du changement climatique à partir de la comparaison des degrés-jour réfrigération et des degrés-jour chauffage actuels et ceux prévus pour la fin du XXIe siècle.Spatio-temporal variations of air conditioning needs in Andalusia induced by climate change are examined by means of the comparison between present and future heating/cooling degree days

    The siliciclastic Permian-Triassic deposits in Central and Northeastern Iberian Peninsula (Iberian, Ebro and Catalan Basins) : a proposal for correlation

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    The siliciclastic deposits of the Iberian, Ebro and Catalan Basins have been described for more than a century, but facies similarities and a lack of biostratigaphic data have difficulted the correlation of the local stratigraphic units in a general framework up to now. Combining pollen and spores data, the identification of the regional unconformities and hiatuses and the quantitative analysis of the subsidence by backstripping methods, a new correlation scheme for these facies is proposed

    AMISEC: Leveraging Redundancy and Adaptability to Secure AmI Applications

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    Security in Ambient Intelligence (AmI) poses too many challenges due to the inherently insecure nature of wireless sensor nodes. However, there are two characteristics of these environments that can be used effectively to prevent, detect, and confine attacks: redundancy and continuous adaptation. In this article we propose a global strategy and a system architecture to cope with security issues in AmI applications at different levels. Unlike in previous approaches, we assume an individual wireless node is vulnerable. We present an agent-based architecture with supporting services that is proven to be adequate to detect and confine common attacks. Decisions at different levels are supported by a trust-based framework with good and bad reputation feedback while maintaining resistance to bad-mouthing attacks. We also propose a set of services that can be used to handle identification, authentication, and authorization in intelligent ambients. The resulting approach takes into account practical issues, such as resource limitation, bandwidth optimization, and scalability
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