1,144 research outputs found

    A day-ahead irradiance forecasting strategy for the integration of photovoltaic systems in virtual power plants

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    Encouraged by the considerable cost reduction, small-scale solar power deployment has become a reality during the last decade. However, grid integration of small-scale photovoltaic (PV) solar systems still remains unresolved. High penetration of Renewable Energy Sources (RESs) results in technical challenges for grid operators. To address this, Virtual Power Plants (VPPs) have been defined and developed to manage distributed energy resources with the aim of facilitating the integration of RESs. This paper introduces a hybrid irradiance forecasting approach aimed at facilitating the integration of PV systems into a VPP, especially when a historical irradiance dataset is exiguous or non-existent. This approach is based on Artificial Neural Networks (ANNs) and a novel similar hour-based selection algorithm, has been tested for a real PV installation, and has been validated also considering irradiance measurements from an aggregation of ground-based meteorological stations, which emulate the nodes of a VPP. Under a reduced historical dataset, the results show that the proposed similar hour-based method produces the best forecasts with regard to those obtained by the ANN-based approach. This is particularly true for one-month and two-month datasets minimizing the mean error by 16.32% and 9.07% respectively. Finally, to demonstrate the potential of the proposed approach, a comparative analysis has been carried out between the hybrid method and the most used benchmarks in the literature, namely, the persistence method and the method based on similar days. It has been demonstrated conclusively that the proposed model yields promising results regardless the length of the historical dataset.Comunidad de MadridAgencia Estatal de Investigació

    Optimal designs for compartmental models with correlated observations

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    El objetivo del estudio es proveer óptimos tiempos para realizar bioensayos cuando ha habido una entrada accidental de radioactividad.The flow of internally deposited radioisotope particles inside the body of people exposed to inhalation, ingestion, injection or other ways is usually evaluated using compartmental models (see Sánchez and López-Fidalgo, (2003, and López-Fidalgo and Sánchez, 2005). The International Commission on Radiological Protection (ICRP, 1994) describes the model of the human respiratory tract, represented by two main regions. One of these, the thoracic region (lungs) is divided into different compartments. The retention in the lungs is given by a large combination of ratios of exponential sums depending on time. The aim of this work is to provide optimal times for making bioassays when there has been an accidental radioactivity intake and there is interest in estimating it. In this paper, a large two parameter model is studied and a simplified model is proposed in order to obtain optimal designs in a more suitable way. Local c-optimal designs for the main parameters are obtained using the results of López-Fidalgo and Rodríguez-Díaz, 2004). Efficiencies for all the computed designs are provided and compared

    Spider diversity (Arachnida: Araneae) in two different coffee management systems and surrounding tropical forest during two contrasting seasons in Oaxaca, Mexico

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    This study focuses on species richness, abundance, diversity, and seasonal variation of spiders in two coffee plantations with different crop management and a portion of tropical forest in two municipalities of La Costa region of Oaxaca, Mexico, using manual collection, foliage beating and pitfall traps. We collected 2,210 spiders belonging to 35 families, 100 genera and 146 species. The inventory includes 51 new species records for Oaxaca. Completeness values for two estimators indicate that the level of representation of inventories range from 68.25% to 78.44%, and the proportion of singletons range from 33.72% to 38.14%. Spider abundance in the rainy season was significantly lower than during the dry season. Spider abundance in the Tropical Forest was significantly lower than Monoculture site with the foliage beating method. Polyculture was the site with the lowest spider abundance with the pitfall traps. Rarefaction curves did not show significant differences in species richness between the sites and seasons. Hutcheson t-test showed that spider diversity was significantly lower in Monoculture than Tropical Forest during the rainy season. This study contributes to the knowledge of the arachnofauna of Mexico and particularly of the state of Oaxaca.Este estudio se enfoca en la riqueza de especies, abundancia, diversidad y variación estacional de las arañas en dos cultivos de café con diferente manejo y una porción de bosque tropical en dos municipios de la región Costa de Oaxaca, México, utilizando la colecta manual, agitación del follaje y trampas de caída. Se recolectaron 2,210 arañas pertenecientes a 35 familias, 100 géneros y 146 especies. El inventario incluye 51 nuevos registros de especies para Oaxaca. Los valores de completitud de dos estimadores indican que el nivel de representación de los inventarios oscila entre el 68.25 % y el 78.44 %, mientras que la proporción de singletons fue de 33.72 % y 38.14 %. La abundancia de arañas en la estación lluviosa fue significativamente menor que durante la estación secas. La abundancia de arañas en el Bosque Tropical fue significativamente menor que en el Monocultivo con el método de agitación de follaje. El Policultivo fue el sitio con menor abundancia de arañas con el método de trampas de caída. Las curvas de rarefacción no mostraron diferencias significativas en la riqueza de especies entre los sitios y estaciones. La prueba t de Hutcheson mostró que la diversidad de arañas fue significativamente menor en el Monocultivo que en el Bosque Tropical durante la estación lluviosa. Este estudio contribuye al conocimiento de la aracnofauna de México y particularmente del estado de Oaxaca

    Computer-Based Cognitive Training Improves Brain Functional Connectivity in the Attentional Networks: A Study With Primary School-Aged Children

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    We have shown that a computer-based program that trains schoolchildren in cognitive tasks that mainly tap working memory (WM), implemented by teachers and integrated into school routine, improved cognitive and academic skills compared with an active control group. Concretely, improvements were observed in inhibition skills, non-verbal IQ, mathematics and reading skills. Here, we focus on a subsample from the overarching study who volunteered to be scanned using a resting state fMRI protocol before and 6-month after training. This sample reproduced the aforementioned behavioral effects, and brain functional connectivity changes were observed within the attentional networks (ATN), linked to improvements in inhibitory control. Findings showed stronger relationships between inhibitory control scores and functional connectivity in a right middle frontal gyrus (MFG) cluster in trained children compared to children from the control group. Seed-based analyses revealed that connectivity between the r-MFG and homolateral parietal and superior temporal areas were more strongly related to inhibitory control in trained children compared to the control group. These findings highlight the relevance of computer-based cognitive training, integrated in real-life school environments, in boosting cognitive/academic performance and brain functional connectivity

    Propuesta de diseño y distribución de planta para la empresa alambres y mallas S.A

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    Este proyecto busca mejorar la Calidad y Clima Laboral de la empresa ALAMBRES Y MALLAS S.A, desde organizar varias referencias de Mallas y Varillas, hasta poder moldear la Distribución en Planta (Layout), para lograr optimizar tiempos y movimientos, cumplir la demanda de Malla Electrosoldada, tener cada referencia en un lugar definido, exactitud del inventario y organizar de forma adecuada las zonas de almacenamiento. Es un proyecto que busca maximizar el capital, mediante la reubicación de maquinaria y replanteamiento de su Distribución de Planta, para lograr optimizar el proceso, teniendo en cuenta que la empresa ha presentado un crecimiento acelerado en el mercado, y que con estas mismas herramientas y organización lo puede logar

    Lupinus angustifolius Protein Hydrolysates Reduce Abdominal Adiposity and Ameliorate Metabolic Associated Fatty Liver Disease (MAFLD) in Western Diet Fed-ApoE−/− Mice

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    Metabolic-associated fatty liver disease (MAFLD) is the most important cause of liver disease worldwide. It is characterized by the accumulation of fat in the liver and is closely associated with abdominal obesity. In addition, oxidative stress and inflammation are significant features involved in MAFLD. Recently, our group demonstrated that lupin protein hydrolysates (LPHs) had lipid lowering, antioxidant, and anti-inflammatory effects. Sixty male mice fed with a Western diet were intragastrically treated with LPHs (or vehicle) for 12 weeks. Liver and adipose tissue lipid accumulation and hepatic inflammatory and oxidant status were evaluated. A significant decrease in steatosis was observed in LPHs-treated mice, which presented a decreased gene expression of CD36 and LDL-R, crucial markers in MAFLD. In addition, LPHs increased the hepatic total antioxidant capacity and reduced the hepatic inflammatory status. Moreover, LPHs-treated mice showed a significant reduction in abdominal adiposity. This is the first study to show that the supplementation with LPHs markedly ameliorates the generation of the steatotic liver caused by the intake of a Western diet and reduces abdominal obesity in ApoE−/− mice. Future clinical trials should shed light on the effects of LPHs on MAFLD.Ministerio de Economía y Competitividad [AGL2012-40247-C02-01 and AGL2012-40247-C02-02]Andalusian Government Ministry of Health [PC-0111-2016-0111]PAIDI Program from the Andalusian Government [CTS160]Spanish Ministerio de Educación, Cultura y Deporte [FPU16/02339] and [FPU13/01210]The National Net RETICEF for Aging Studies (RD12/0043/0012 from the Instituto de Salud Carlos III, Spanish Ministerio de Ciencia e Innovación)European Social Fund and Spanish Ministerio de Empleo y Seguridad Social [EJ-086]Andalusian Government Ministry of Health [PI-0136-2019]VI Program of Inner Initiative for Research and Transfer of University of Seville (VI PPIT-US

    Analytical solution of temperature distribution in a homogeneous medium due to a rectangular wave-shaped electrical wire [Solución analítica de la distribución de temperaturas en un medio homogéneo debido a un cable eléctrico con forma de onda rectangular]

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    RESUMEN Debido a la limitada cantidad de reservas de petróleo, es fundamental garantizar el uso eficiente de la energía disponible, lo cual está íntimamente ligado al diseño óptimo de los equipos eléctricos. Estos equipos (por funcionar con energía eléctrica) no pueden evitar tener fuentes discretas de generación de calor y su diseño depende de la determinación precisa del campo de temperaturas en todo el cuerpo. En este trabajo se utiliza el método integral de las funciones de Green para determinar la distribución de temperaturas tridimensional de un medio homogéneo debido a una fuente de generación de calor con forma de onda rectangular. La geometría de la generación de calor ha sido seleccionada de tal manera que tenga la forma típica de los calentadores eléctricos flexibles que se encuentran comercialmente disponibles. La solución obtenida es exacta y matemáticamente simple. Para demostrar la versatilidad de los resultados, esta solución analítica ha sido comparada con la solución puramente numérica obtenida usando un paquete computacional de amplio uso en ingeniería (COMSOL Multiphysics). Los resultados analíticos y numéricos coinciden en todos los rangos evaluados. Usando la ecuación obtenida en este trabajo, se propone un procedimiento sencillo para determinar la conductividad térmica efectiva de un material a partir de los datos experimentales de temperatura y posición. Los resultados de esta investigación pueden ser aplicados en el diseño de dispositivos termo-ópticos, calentadores eléctricos flexibles o dispositivos microfluídicos termo-regulables y ofrecen un método conveniente para obtener la conductividad térmica efectiva de un material. PalabrasABSTRACT Due to the limited amount of oil reserves, it is essential to ensure the efficient use of available energy, which is closely linked to the optimal design of electrical devices. Because these devices work with electrical energy, they cannot avoid having discrete heat generating sources and their design depends on the precise determination of the temperature field in the body. In this work, the integral method of Green's functions is used to determine the three-dimensional temperature distribution of a homogeneous medium due to a rectangular waveshaped heat generation source. The geometry of the heat generation has been selected in such a way that it has the typical shape of the commercially available flexible electric heaters. The solution obtained is exact and mathematically simple. To demonstrate the versatility of the results, this analytical solution has been compared with the purely numerical solution obtained using a computer package widely used in engineering (COMSOL Multiphysics). The analytical and numerical results coincide well in all the evaluated ranges. Using the equation obtained in this work, a procedure is proposed to determine the effective thermal conductivity of a material from the experimental data of temperature and position. The results of this research offer a simple way to calculate the thermal conductivity of a material and can be applied in the design of thermo-optical devices, flexible electric heaters or thermo-adjustable microfluidic devices

    Safety and Efficacy of a Beverage Containing Lupine Protein Hydrolysates on the Immune, Oxidative and Lipid Status in Healthy Subjects: An Intervention Study (the Lupine-1 Trial)

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    Scope: We have previously demonstrated the anti-inflammatory and antioxidant properties of in vitro administered Lupinus angustifolius protein hydrolysates (LPHs) on human peripheral blood mononuclear cells (PBMCs). This study aims to evaluate the safety and efficacy of a beverage containing LPHs (LPHb) on the immune, oxidative and metabolic status of healthy subjects. Methods and Results: In this open-label intervention, 33 participants daily ingest a LPHb containing 1 g LPHs for 28 days. Biochemical parameters are assayed in fasting peripheral blood and urine samples before, during (14 days) and after LPHb ingestion. Participants’ health status and the immune and antioxidant responses of PBMCs are also evaluated throughout the trial. The LPHb ingestion is safe and effective in both increasing the anti-/pro-inflammatory response of PBMCs and improving the cellular anti-oxidant capacity. LPHb also reduces the low-density lipoprotein-cholesterol (LDL-C)/high-density lipoprotein-cholesterol (HDL-C) atherogenic index. LPHb effect is particularly beneficial on decreasing not only the LDL-C/HDL-C index but also serum total cholesterol levels in the male cohort that shows the highest baseline levels of well-known cardiovascular risk factors. Conclusion: This is the first study to show the pleiotropic actions of a lupine bioactive peptides-based functional food on key steps of atherosclerosis including inflammation, oxidative stress, and cholesterol metabolism.Ministerio de Economía y Competitividad AGL2012-40247-C02-01, AGL2012-40247- C02-02Junta de Andalucía PC-0111-2016- 0111, CTS160Ministerio de Ciencia e Innovación RD06/0013/0001, RD12/0043/001
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