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

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

Moscas de las frutas (Díptera: Tephritidae) y parasitoides asociados con Psidium guajava L. y Coffea arabica L. en tres municipios de la Provincia de Vélez (Santander, Colombia). Parte 1: Índices de infestación y daño por moscas de la frutas

This research took place in the Province of Velez in Santander, Colombia (5° 33’ – 5°88’ N and 73° 42’ – 73° 48’ W)   in the municipalities of Guavatá, Puente Nacional and Jesús María (1.650 – 1.890 masl, 17,8° C; 1800- 2500 ml of  rain/year; 93% of HR) in crops of Psidium guajava L. and Coffea arabica L. The objective was to identify and measure the crop damage caused by fruit flies on both species. Sampling was carried out for two years. Samples of mature fruits from each host plant were monthly taken from the trees, in three plots per location. Fruits were separately evaluated for the presence of larvae. The number of third instar larvae (L3), pupae and adults per sample was registered by species and sex. A total of 216 samples were analyzed per host plant which corresponded to 217, 42 kg of guava and 213,75 kg of coffee. Results indicated the presence of Anastrepha striata Schiner and A. fraterculus (Wied) emerging from guava and coffee. The attack proportion in guava was 91,72% caused by A. striataand only 8,26% caused by A. fraterculus. In coffee A. striata caused 0,85% of the attack while A. fraterculus caused 99,15% of the attack. Male: female ratio was 1:1 for both species. Average percent of total damage per year was 99,86% in 2000 and of 96,20% in 2001 for guava; no statistical differences within years were found. The infestation index [L3/kg of fruit] was 153.3 in the first year and 214,9 in the second year, significant differences among years and localities were found. Percentage of fruit damage was lower in coffee when compared to guava (18,93% in the first year and 22,23% in the second). The infestation [L3/kg] in the first year was 110,6 and 120,83 in the second (P>0.05). La investigación se realizó en la Provincia de Vélez (5° 33’ – 5° 88’ Norte y 73° 42’ – 73° 48’ Oeste) en el Departamento de Santander (Colombia) en los municipios de Guavatá, Puente Nacional y Jesús María (1.650 – 1.890 msnm, 17,8° C; 1.800-2.500 ml de precipitación por año; 93% de humedad relativa) en Psidium guajava L. y Coffea arabica L., con el objeto de identificar y cuantificar el daño causado por moscas de las frutas. Se tomaron frutas maduras del árbol en tres fincas de cada localidad, una vez por mes durante los años 2000 y 2001. Las muestras se procesaron y analizaron y se contó el número de larvas del tercer instar, pupas y adultos de moscas emergidas. Éstas se agruparon por especie y sexo y se analizaron los datos promedios anuales por localidad y especie. Se analizaron 216 muestras de cada planta hospedante, equivalentes a 217,42 kg de guayaba y 213,75 kg de café. Emergieron las especies Anastrepha striata Schiner y A. fraterculus (Wied). En guayaba la relación fue del 91,72% de A. striata y 8,26% de A. fraterculus. En café 0,85% de A. striata y 99,18% de A. fraterculus. La relación de sexos de cada especie se mantuvo en 1:1. El porcentaje de frutas dañadas, promedio total anual, fue de 99,86% en el año 2000 y de 96,20% en el año 2001. No hubo diferencias significativas entre años ni localidades. Los índices de infestación (L3/kg de fruta) fueron de 153,3 en el año 2000 y de 214,9 en el año 2001 y hubo diferencias significativas entre años y localidades. En café, el porcentaje de daño y el índice de infestación fueron significativamente inferiores respecto a los de guayaba, y el promedio total anual fue de 18,93% en el año 2000 y de 22,23% en el año 2001. La infestación L3/kg) en el primer año fue de 110,6 y de 120,83 en el segundo año. Se observaron diferencias significativas entre localidades.

Moscas de las frutas (Díptera: Tephritidae) y parasitoides asociados con Psidium guajava L. y Coffea arabica L. en tres municipios de la Provincia de Vélez (Santander, Colombia) Parte 2: Identificación y evaluación de parasitoides del Orden Hymenoptera.

This research took place in the Province of Velez in Santander, Colombia (5°33’ – 5°88’ N and 73°42’ – 73°48’ W)  in the municipalities of Guavatá, Puente Nacional and Jesús María (1.650 – 1.890 masl, 17,8°C; 1800-2500 ml of rain/year; 93% of HR) in crops of Psidium guajava L. and Coffea Arabica L. Fruits were monthly sampled, for a period of two years. A total of 216 samples from each crop were evaluated until parasitoid emergency; nonopened pupae were dissected and the no emerged parasitoid were classified and counted. The presence of the following species could be detected: Doryctobracon crawfordi (Viereck), Utetes (Bracanastrepha) anastrephae (Viereck), Microcrasis sp(Braconidae), Aganaspis pelleranoi (Brèthes), Odontosema anastrephae (Borgmeier) (Figitidae) andAceratoneuromyia indica (Silvestri) (Eulophidae). The total percentage of parasotoidism of Anastrepha striata and A. fraterculus in guava was 0,86 and 0,58% (first and second year, respectively); and 5,41 and 4,52% in A. fraterculus in coffee. The parasitism percentage in each species per year are presented and analysed. La investigación se realizó en la Provincia de Vélez (5° 33’ – 5° 88’ Norte y 73° 42’ – 73° 48’ Oeste) en el Departamento de Santander (Colombia) en los municipios de Guavatá, Puente Nacional y Jesús María (1.650 – 1.890 msnm 17,8° C; 1.800-2.500 ml de precipitación por año; 93% de humedad relativa). Se tomaron muestras de frutas del árbol Psidium guajava L. y Coffea arabica L. una vez por mes durante los años 2000 y 2001. Se analizaron y procesaron 216 muestras de cada cultivo, hasta la emergencia de parasitoides; las pupas sin signos de emergencia se disectaron a los 45 días después de tomada la muestra y se clasificaron y contaron los parasitoides en desarrollo. Se identificaron las especies del orden Hymenóptera Doryctobracon crawfordi (Viereck), Utetes (Bracanastrepha) anastrephae (Viereck), Microcrasis sp. (Braconidae), Aganaspis pelleranoi (Brèthes), Odontosema anastrephae (Borgmeier) (Figitidae) y Aceratoneuromyia indica (Silvestri) (Eulophidae). Los porcentajes de parasitoidismo total por año en Anastrepha striata – fraterculus en guayaba fueron de 0,86 y 0,58% para cada año; y en A. fraterculus en café fueron de 5,41 y 4,52%. Se calcularon y analizaron los porcentajes anuales de parasitismo por cada especie de parasitoide. 

Actividad antibacteriana y alguicida de compuestos de origen natural

Las pinturas usadas en fachadas suelen sufrir biodeterioro por microorganismos. Las plantas sintetizan metabolitos secundarios que podrían constituir una alternativa sustentable a los biocidas tradicionalmente empleados para combatirlos. El objetivo del trabajo fue evaluar la actividad antibacteriana y alguicida de guayacol, eugenol, timol y anisol para su posterior incorporación en pinturas de exterior.Centro de Investigación y Desarrollo en Tecnología de Pintura

Actividad antibacteriana y alguicida de compuestos de origen natural

Las pinturas usadas en fachadas suelen sufrir biodeterioro por microorganismos. Las plantas sintetizan metabolitos secundarios que podrían constituir una alternativa sustentable a los biocidas tradicionalmente empleados para combatirlos. El objetivo del trabajo fue evaluar la actividad antibacteriana y alguicida de guayacol, eugenol, timol y anisol para su posterior incorporación en pinturas de exterior.Centro de Investigación y Desarrollo en Tecnología de Pintura

Actividad antibacteriana y alguicida de compuestos de origen natural

Las pinturas usadas en fachadas suelen sufrir biodeterioro por microorganismos. Las plantas sintetizan metabolitos secundarios que podrían constituir una alternativa sustentable a los biocidas tradicionalmente empleados para combatirlos. El objetivo del trabajo fue evaluar la actividad antibacteriana y alguicida de guayacol, eugenol, timol y anisol para su posterior incorporación en pinturas de exterior.Centro de Investigación y Desarrollo en Tecnología de Pintura

Optimal estimation of the roughness coefficient and friction factor of a pipeline

This work addresses the estimation of two interrelated parameters of the fluid flow in pipes. First, a numerical and experimental evaluation of some proposed methods to compute the friction factor in turbulent regime is presented. Special attention is given to an explicit solution obtained through the Lambert W-function. Subsequently, a method to estimate the roughness coefficient using nonlinear optimization techniques is proposed, which then allows determining the friction factor from it. Numerical tests were performed for a wide range of operating points of a pipeline. In order to validate the proposed approach, experimental analysis was carried out on a pipeline pilot-plant. The results show the applicability and effectiveness of the proposed method.Postprint (author's final draft

Clinical Characteristics and Prognosis of COPD Patients Hospitalized with SARS-CoV-2

Objective To describe the characteristics and prognosis of patients with COPD admitted to the hospital due to SARS-CoV-2 infection. Methods The SEMI-COVID registry is an ongoing retrospective cohort comprising consecutive COVID-19 patients hospitalized in Spain since the beginning of the pandemic in March 2020. Data on demographics, clinical characteristics, comorbidities, laboratory tests, radiology, treatment, and progress are collected. Patients with COPD were selected and compared to patients without COPD. Factors associated with a poor prognosis were analyzed. Results Of the 10,420 patients included in the SEMI-COVID registry as of May 21, 2020, 746 (7.16%) had a diagnosis of COPD. Patients with COPD are older than those without COPD (77 years vs 68 years) and more frequently male. They have more comorbidities (hypertension, hyperlipidemia, diabetes mellitus, atrial fibrillation, heart failure, ischemic heart disease, peripheral vascular disease, kidney failure) and a higher Charlson Comorbidity Index (2 vs 1, p<0.001). The mortality rate in COPD patients was 38.3% compared to 19.2% in patients without COPD (p<0.001). Male sex, a history of hypertension, heart failure, moderate–severe chronic kidney disease, presence of cerebrovascular disease with sequelae, degenerative neurological disease, dementia, functional dependence, and a higher Charlson Comorbidity Index have been associated with increased mortality due to COVID-19 in COPD patients. Survival was higher among patients with COPD who were treated with hydroxychloroquine (87.1% vs 74.9%, p<0.001) and with macrolides (57.9% vs 50%, p<0.037). Neither prone positioning nor non-invasive mechanical ventilation, high-flow nasal cannula, or invasive mechanical ventilation were associated with a better prognosis. Conclusion COPD patients admitted to the hospital with SARS-CoV-2 infection have more severe disease and a worse prognosis than non-COPD patients