A fitting procedure for probability density functions of service restoration times. Application to underground cables in medium-voltage networks

Distribution companies have the responsibility to provide a quality service to their customers, according to the existing regulation. Reliability issues, such as power outages, are registered in databases for a quantitative evaluation of this quality. This paper uses one of these historical records to make a statistical analysis of service restoration times, applied to the particular case of underground cables in medium voltage networks. An algo-rithm is proposed to fit the raw data to the probability density functions typically used in reliability analysis. The best-fitted distribution is determined in each case according to the information provided by a set of goodness-of -fit tests. Different groups are considered for the elements of the systems, concerning their functionality and voltage level. The presented procedure is applied to an electrical network with more than 350 feeders. Results have been obtained globally, showing that the observed service restoration time is lower than the estimated maximum limit in 98.00% of cases. The probability functions provided by the proposed algorithm can be used to improve the accuracy of the reliability models for the electric power system.8 página

PITCAIRNIA ABUNDANS L.B.SM. (BROMELIACEAE): SUPPLEMENTARY DESCRIPTION, RANGE EXTENSION AND CONSERVATION STATUS OF AN ENDEMIC MEXICAN PLANT

A supplementary description of Pitcairniaabundans is presented based on newspecimens collected at or near the typelocality in Nayarit and from a new locationin Jalisco, which extends its known rangeabout 115 km. We present previouslyunknown information from fresh flowers,fruits and seeds, as well as phenology offlowering and fruiting. The applicationof the method for the assessment of extinction risk in Mexican wild species (MER)resulted in endangered status for thisspecies.Se presenta una descripción suplementariade Pitcairnia abundans con base en nuevos especímenes recolectados en Nayarit,en o cerca de la localidad tipo y de una nueva localidad en Jalisco, la cual extiende sudistribución conocida en aproximadamente115 km. Presentamos información nuevade flores en antesis, de frutos y semillas, asícomo de fenología de floración y fructificación. La aplicación del método para laevaluación del riesgo de extinción en especies silvestres mexicanas (MER) resultó enun estatus de ‘‘en peligro de extinción’’ paraesta especie

Modelado y análisis de la evolución de una epidemia vírica mediante filtros de Kalman: el caso del COVID-19 en España

Documento de trabajo. Difundido en idUS a solicitud de los autoresEste trabajo presenta una metodología original para el tratamiento de los datos reportados de positivos y fallecidos por una epidemia vírica. El objetivo principal es caracterizar la evolución de la progresión del número de infectados reales, y en consecuencia poder predecir en qué momento se alcanzará el pico de la epidemia en un caso de estudio concreto, en este caso la del Covid-19 en España. Los resultados obtenidos muestran claramente el efecto beneficioso de las medidas de confinamiento adoptadas, y prevén que el pico se producirá aproximadamente a finales de marzo o principios de abri

Identification of the phase connectivity in distribution systems through constrained least squares and confidence-based sequential assignment

This paper addresses the customer-phase identification problem in three-phase distribution grids including three-phase customers characterized by aggregated energy measurements. The proposed technique first solves a relaxed problem, in which the binary nature of the variables is ignored, which leads to a constrained, least-squares estimation, using as inputs the active and reactive energy readings provided by the smart meters, along with the energy delivered by each phase at the head of the feeder. With the estimated values of the decision variables, and their corresponding variances, a confidence-based selection technique is then applied for the sequential assignment of the customer with the highest joint probability of being connected to one of the three phases but not to the other two. The performance of the proposed procedure is assessed with five different scenarios in terms of accuracy for increasing number of loads and measurement errors. The robustness of the algorithm is additionally tested in the presence of model errors, and its performance is compared to that of existing methods.Project Solar to Vehicle (S2V) INV-3-2021-I-038Research project HySGrid+ CER-2019101

Nuevas técnicas metodologías para el fomento de habilidades transversales y transferencia del conocimiento en universitarios

Knowledge transference and its business potential are very much related to founders’ skills, and especially to the development of their transversal skills. Unfortunately, the time needid to achieve these skills spontaneously penalizes their possibilities. The implementation of pilot experiences in application of agile innovation methodologies such as "Lean Startup" and "Scrum" to real business projects during their incubation and acceleration process at the University of Seville has thrown interesting data about the best work dynamics during the process, with measurements of productivity, the "momentum" of the project, its "focus abilities" or qualitative assessments of those involved in the study. The results reveal a series of advantages and disadvantages derived from the application of these methodologies, which exert influence both on the individual performance and on the group of founders, that in general have turned out to be positive, since they allow to accelerate the maturation process to achieve the skills needed to increase survival ratios, or to conclude that it is not a viable project by making use of significantly less time and resources.La transferencia del conocimiento y su potencial empresarial están muy relacionadas con la capacidad del equipo promotor, y especialmente con el desarrollo de habilidades transversales. Por desgracia, el tiempo necesario para lograr estas habilidades de forma espontánea penaliza sus posibilidades. La puesta en marcha de experiencias piloto de aplicación de metodologías ágiles de innovación como “Lean Startup” y “Scrum” a proyectos empresariales reales durante su proceso de incubación y aceleración en la Universidad de Sevilla ha permitido obtener datos interesantes acerca de la dinámica de trabajo individual y grupal registrada durante el proceso, con mediciones de la productividad, el “nivel de inercia” del proyecto, su “capacidad de foco” o valoraciones cualitativas de los implicados en el estudio. Los resultados descubren una serie de ventajas e inconvenientes derivados de la aplicación de estas metodologías, que ejercen influencia tanto en el desempeño individual como del conjunto de fundadores del proyecto, y en líneas generales han resultado ser positivos, ya que permiten acelerar el proceso de maduración personal hacia la consecución de las habilidades necesarias para incrementar la supervivencia del proyecto, o bien para concluir que no es viable haciendo uso de una cantidad significativamente inferior de tiempo y recursos

E-Learning through an Adaptive cMOOC: Is it Worthyof Further Research?

This paper describes the types of MOOC considered by researchers, and highlights the latter's focus on Connectivist MOOC. In addition, it analyses MOOC methodologies, and learners' interest in MOOC based on the concepts of adaptability, connectivism, and socio-constructivism. This is to address the high dropout rate issue on MOOC platforms. The main objective of this work is to review the empirical results reported in these studies. To reach this goal, a Systematic Literature Review of 798 papers was carried out from 2013 until April 2021, where 446 papers were selected as primary studies. The results obtained from the classification and the analysis of the collected data confirmed the importance of continuing research in the field. Based on the concepts of socio-constructivism and adaptability, the objective is to provide an adaptive cMOOC for the profile and the needs of each learner; blending learning styles and pedagogical models with machine learning technologies

Nanostructured Ti thin films by magnetron sputtering at oblique angles

The growth of Ti thin films by the magnetron sputtering technique at oblique angles and at room temperature is analysed from both experimental and theoretical points of view. Unlike other materials deposited in similar conditions, the nanostructure development of the Ti layers exhibits an anomalous behaviour when varying both the angle of incidence of the deposition flux and the deposition pressure. At low pressures, a sharp transition from compact to isolated, vertically aligned, nanocolumns is obtained when the angle of incidence surpasses a critical threshold. Remarkably, this transition also occurs when solely increasing the deposition pressure under certain conditions. By the characterization of the Ti layers, the realization of fundamental experiments and the use of a simple growth model, we demonstrate that surface mobilization processes associated to a highly directed momentum distribution and the relatively high kinetic energy of sputtered atoms are responsible for this behaviourJunta de Andalucía P12-FQM- 2265Ministerio de Ciencia e Innovación CSD2008- 00023, MAT2013-42900-P, MAT2013-40852-R, MAT2014-59772-C2-1, MAT2011- 2908

Influence of the wind variability on the calculation of dynamic line rating

This paper presents a novel technique to calculate the ampacity of an overhead transmission line in real time, considering the dynamic evolution of the conductor temperature. In case this method cannot be applied due to lack of adequate information, a correction is proposed for the maximum current, based on Monte Carlo simulations assuming unfavorable external conditions, and validated with real data from a weather station. This technique might be used to avoid the temporary violation of the minimum electrical clearance in transmission lines.Research project HySGrid+ CER-2019101