2,799 research outputs found
Aquatic Perceived Competence Analysis in Children: Development and Preliminary Validation of a Pictorial Scale
The aim of this study was to develop and validate a scale for measuring perceived motor of children in the water (also known as aquatic perceived competence). One hundred boys and girls four and five years old took part in the study and were given a picture questionnaire featuring a series of images of children engaged in a variety of water tasks. Factor analyses were conducted to test whether the ten-item scale is made up of two major dimensions, the first of them referring to willingness (predisposition or attitudes of the children towards water) and the second to the perceived skill competence in water. This instrument was shown to have suitable psychometric properties both on the overall scale (α = .92) and on the two sub-scales: willingness (α = .93) and motor capability (α = .85), with the eldest participants registering the highest values. The Aquatic Perceived Competence Pictorial Scale (APCPS) for children is recommended as an instrument of use to researchers and swimming instructors to use for assessing the aquatic perceived competence of their students
Arc fault protections for aeronautic applications: a review identifying the effects, detection methods, current progress, limitations, future challenges, and research needs
©2022 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.Arc faults are serious discharges, damaging insulation systems and triggering electrical fires. This is a transversal topic, affecting from residential to aeronautic applications. Current commercial aircrafts are being progressively equipped with arc fault protections. With the development of more electric aircrafts (MEA), future airliners will require more electrical power to enhance fuel economy, save weight and reduce emissions. The ultimate goal of MEAs is electrical propulsion, where fault management devices will have a leading role, because aircraft safety is of utmost importance. Therefore, current fault management devices must evolve to fulfill the safety requirements of electrical propelled aircrafts. To deal with the increased electrical power generation, the distribution voltage must be raised, thus leading to new electrical fault types, in particular arc tracking and series arcing, which are further promoted by the harsh environments typical of aircraft systems, i.e., low pressure, extreme humidity and a wide range of temperatures. Therefore, the development of specific electrical protections which are able to protect against these fault types is a must. This paper reviews the state-of-the-art of electrical protections for aeronautic applications, identifying the current status and progress, their drawbacks and limitations, the future challenges and research needs to fulfill the future requirements of MEAs, with a special emphasis on series arc faults due to arc tracking, because of difficulty in detecting such low-energy faults in the early stage and the importance and harmful effects of tracking activity in cabling insulation systems. This technological and scientific review is based on a deep analysis of research and conference papers, official reports, white papers and international regulations.This research was partially funded by the Ministerio de Ciencia e Innovación de España, grant number PID2020-114240RB-I00 and by the Generalitat de Catalunya, grant number 2017 SGR 967.Peer ReviewedPostprint (author's final draft
Rhynchospora fusca (l.) W.T. Aiton de la turbera de Llano Roñanzas (llanes, Asturias)
Se confirma la subsistencia actual de Rhynchospora fusca en la turbera de Llano Roñanzas, Llanes, Principado de Asturias.The
current subsistence of Rhynchospora fusca in the Llano Roñanzas peat bog, Llanes, Principality of Asturias is confirmed
Predicción del soporte de autonomía, los mediadores psicológicos y la motivación académica sobre las competencias básicas en estudiantes adolescentes
El objetivo de este estudio fue comprobar el poder de predicción del soporte de autonomía, los mediadores psicológicos y la motivación académica autodeterminada sobre las competencias básicas. Se utilizó una muestra de 405 estudiantes adolescentes con edades comprendidas entre los 12 y 16 años a los que se les midió el soporte de autonomía, las necesidades psicológicas, la motivación autodeterminada y las competencias básicas. Los resultados apoyaron la estructura unifactorial y mostraron que la escala de competencias básicas era válida y fiable para medir su objetivo. El soporte de autonomía del docente, los iguales, el padre y la madre, los mediadores psicológicos y la motivación académica autodeterminada predijeron las competencias básicas.; The purpose of this study was to examine the prediction that the autonomy supportive, the psychological mediators and the academic autodeterminated motivation had in the basic competences. A sample of 405 students with ages understood between the 12 an d the 16 years was used. It measured the autonomy supportive, the basic psychological needs, the academic autodeterminated motivation and the basic competences. The results supported the factorial structure and showed that the scale had an appropriate validity and reliability to measure the basic competences. The autonomy supportive of the teacher, the classmates, the father and the mother, the basic psychological needs and the academic autodeterminated motivation predicted the basic competences
Detailed off-line parameter identification of synchronous generator based on frequency response tests
This work presents a general methodology, based
on standstill frequency response tests. Once the circuit topology is
chosen, it allows a systematic calculation of the circuit
parameters for a salient pole synchronous generator. The order
of the circuit considered can be whatever, even a customized
circuit topology, since the methodology does not rely on a specific
formulation. The transfer function coefficients are expressed as a
function of the circuit parameters by using the symbolic Matlab
toolbox. From tests, the coefficients of the transfer function are
fitted in both axes. Then the coefficients have to match with the
symbolic transfer function previously obtained in order to
calculate the circuit parameters. If the dynamic behavior
obtained with the fitted parameters is not accurate enough, the
circuit order is increased until attaining an accurate solution.
This methodology results in a useful educational tool for machine
characterization. Nowadays many methods are found in the
technical literature to calculate such parameters, although most
of them computationally demanding.Peer ReviewedPostprint (published version
Cross-sectional study of height and weight in the population of Andalusia from age 3 to adulthood
<p>Abstract</p> <p>Background and objectives</p> <p>In Andalusia there were no studies including a representative sample of children and adolescent population assessing growth and weight increase. Our objectives were to develop reference standards for weight, height and BMI for the Andalusian pediatric population, from 3 to 18 years of age for both genders, and to identify the final adult height in Andalusia.</p> <p>Subjects and methods</p> <p>Two samples were collected. The first included individuals from 3 to 18 years of age (3592 girls and 3605 boys). They were stratified according type of study center, size of population of origin, age (32 categories of 0.5 years) and gender, using cluster sampling. Subjects from >18 to 23 years of age (947 women and 921 men) were sampled in 6 non-university educational centers and several university centers in Granada. Exclusion criteria included sons of non-Spanish mother or father, and individuals with chronic conditions and/or therapies affecting growth. Two trained fellows collected the data through February to December 2004, for the first sample, and through January to May 2005, for the second.</p> <p>Reference curves were adjusted using Cole's LMS method, and the quality of the adjustment was assessed using the tests proposed by Royston. In addition, a sensitivity analysis was applied to the final models obtained.</p> <p>Results</p> <p>Data for 9065 cases (4539 women and 4526 men) were obtained; 79.39% (n = 7197) in the up to 18 years of age group. In the first sampling only 0.07% (3 girls and 2 boys) refused to participate in the study. In addition, 327 students (4.5%) were absent when sampling was done. We present mean and standard deviation fort height, weight and BMI at 0.5 years intervals, from 3 to 23 years of age, for both genders. After adjustment with the different models, percentiles for height, weight (percentiles 3, 5, 10, 25, 50, 75, 90, 95, and 97) and BMI (percentiles 3, 5, 50, 85, 95, and 97) are presented for both genders.</p> <p>Conclusion</p> <p>This is the first study in Andalusia with a representative sample from the child-juvenile population to investigate weight, height and BMI in subjects from 3 to 23 years of age. The great variability observed in the values from sample of 18 to 23 years of age individuals, ensures the inclusion of extreme values, although random sampling was not used. There still is a lack of standard reference values for the Andalusian population younger done 3 years of age.</p
General Purpose Transistor Characterized as Dosimetry Sensor of Proton Beams
This research has been partially funded by Junta de Andalucía (Spain), project numbers
PI-0505-2017 FEDER/Junta de Andalucía-Consejería de Economía y Conocimiento Project B-TIC-468-
UGR18; Ministerio de Ciencia e Innovación, Proyecto del Plan Nacional I + D: PID2019-104888 GB-I00
and Proyectos I + D + i Junta de Andalucía 2018: P18-RT-3237. This work has been also conducted in
the framework of European Union H2020 ELICSIR project (grant No. 857558).A commercial pMOS transistor (MOSFET), 3N163 from Vishay (USA), has been character-
ized as a low-energy proton beam dosimeter. The top of the samples’ housing has been removed to
guarantee that protons reached the sensitive area, that is, the silicon die. Irradiations took place at
the National Accelerator Centre (Seville, Spain). During irradiations, the transistors were biased to
improve the sensitivity, and the silicon temperature was monitored activating the parasitic diode of
the MOSFET. Bias voltages of 0, 1, 5, and 10 V were applied to four sets of three transistors, obtaining
an averaged sensitivity that was linearly dependent on this voltage. In addition, the short-fading
effect was studied, and the uncertainty of this effect was obtained. The bias voltage that provided
an acceptable sensitivity, (11.4 ± 0.9) mV/Gy, minimizing the uncertainty due to the fading effect
(−0.09 ± 0.11) Gy was 1 V for a total absorbed dose of 40 Gy. Therefore, this off-the-shelf electronic
device presents promising characteristics as a dosimeter sensor for proton beams.Junta de Andalucia
B-TIC-468-UGR18Ministry of Science and Innovation, Spain (MICINN)
2018: P18-RT-3237European Commission
PI-0505-2017 FEDERJunta de Andalucia-Consejeria de Economia y Conocimiento ProjectPID2019-104888 GB-I00European Union H2020 ELICSIR project 85755
Variables motivacionales relacionadas con la práctica deportiva extraescolar en estudiantes adolescentes de educación física
El objetivo del estudio fue conocer los diferentes perfiles motivacionales que subyacen en una muestra de 819 estudiantes adolescentes de educación física y su relación con la práctica y el tiempo de práctica físico-deportiva. Se han utilizado los cuestionarios de orientación al aprendizaje y el rendimiento en las clases de educación física (LAPOPECQ), la Escala de Motivación Deportiva (SMS) y la Escala de la Importancia y Utilidad concedida por el alumno a la educación física (IEF). El análisis cluster mostró tres perfiles motivacionales: el “perfil autodeterminado”, compuesto por participantes que percibían un clima que primaba la importancia al esfuerzo, la mejora personal y el desarrollo de las habilidades (clima tarea) y con una alta motivación intrínseca, el “perfil no autodeterminado” compuesto por sujetos que presentaban una alta desmotivación y que percibían un clima que daba prioridad a la demostración de la capacidad personal y al rendimiento (clima ego) y por último, el “perfil desmotivado” formado por personas que han obtenido valores bajos en casi todas las variables (motivación intrínseca y extrínseca, clima motivacional e importancia y utilidad concedida a la educación física), excepto en la desmotivación. Los practicantes y los que más tiempo dedican a la práctica se asocian con el perfil autodeterminado. Conocer estos perfiles nos permitirá establecer modos de actuación más adecuados, tratando así de reducir al máximo el abandono de la práctica deportiva ajustándonos al grado de motivación del sujeto
Parameter identification of DC-DC converters under steady-state and transient conditions based on white-box models
This paper proposes a white-box approach for identifying the parameters of DC-DC buck and boost switch mode power converters. It is based on discretizing the differential equations that describe the dynamic behavior of the converters. From the discretized equations and experimental data, the parameters of the converters are identified, thus obtaining both the values of the passive components and the transfer function coefficients of the controller. To this end, steady state and transient experimental signals are analyzed, including the input and output voltages and the inductor and output currents. To determine the accuracy of the proposed method, once the parameters are identified, a simulation with the identified parameters of the converter is run and compared with experimental signals. Such results show the accuracy and feasibility of the approach proposed in this
work, which can be extended to other converters and electrical and electronic devices.Peer ReviewedPostprint (published version
Demand and Storage Management in a Prosumer Nanogrid Based on Energy Forecasting
Energy efficiency and consumers' role in the energy system are among the strategic research topics in power systems these days. Smart grids (SG) and, specifically, microgrids, are key tools for these purposes. This paper presents a three-stage strategy for energy management in a prosumer nanogrid. Firstly, energy monitoring is performed and time-space compression is applied as a tool for forecasting energy resources and power quality (PQ) indices; secondly, demand is managed, taking advantage of smart appliances (SA) to reduce the electricity bill; finally, energy storage systems (ESS) are also managed to better match the forecasted generation of each prosumer. Results show how these strategies can be coordinated to contribute to energy management in the prosumer nanogrid. A simulation test is included, which proves how effectively the prosumers' power converters track the power setpoints obtained from the proposed strategy.Spanish Agencia Estatal de Investigacion ; Fondo Europeo de Desarrollo Regional
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