Search results for "reliability"

Equivalent Circuit Modelling of Ferrite Inductors Losses

2018

The modelling of the magnetic losses in the core of ferrite inductors for power conversion circuits has been considered in this paper. On the basis of the Revised Generalized Steinmetz Model (RGSE) an equivalent circuital modelling has been obtained. The losses are modelled as an equivalent resistance connected in parallel to the inductor. The model has been tested under periodic triangular current waveforms.

The reliability of spanish and german electricity forward prices. Databases and price discovery process

2021

Given the existence of different databases from different sources that offer information on forward electricity prices, the need to compare them arises to guarantee that research results and trading decisions based on them are not sensitive to the database used. We worked with forward electricity prices traded over the counter, closest month to maturity, covering the period from 2010 to 2016 for the Spanish over the counter (OTC) market, and from 2008 to 2016 for the German OTC market. The goal of this paper was to test whether there were significant discrepancies between the price series provided by two of the main agencies of financial information (Thomson Reuters and Bloomberg), as well …

Real-Time Minimization Power Losses by Driven Primary Regulation in Islanded Microgrids

2020

Islanded microgrids are small networks that work independently from the main grid. The frequency and voltage in islanded microgrids are affected directly by the output power of distributed generators and power demand variations. In this work, a real-time driven primary regulation, which relies on optimized P-f droop coefficients, is proposed. In all operating conditions, it minimizes the power losses for islanded microgrids. The proposed configuration will allow the optimization modules to interact with each other and adjust parameters producing a suitable power sharing among generators. The methodology is tested based on a hardware-in-the-loop experimental set-up where distributed generato…

Earth resistance measurements in urban contexts: Problems and possible solutions

2017

Both EN 50522 and IEEE Std. 81 propose the Fall of Potential Method (FPM) to carry out the measurement of the resistance to earth of an Earthing System (ES). However, in urban areas, the recommended distances between the ES and auxiliary electrodes are not easy to respect, due to the presence of buildings and tarmac. Moreover, unknown buried metallic parts, as well as the interconnection among the ESs made by the Distributor System Operator, could modify the earth potential profile of the area, affecting the measurement results. In this paper, the issues that could affect the measurement result if FPM is used in an urban context are presented. A parametric analysis, carried out with Comsol …

Considering safety issues in minimum losses reconfiguration for MV distribution networks

2009

This paper offers a new perspective over the traditional problem of the multiobjective optimal reconfiguration of electrical distribution systems in regular working state. The issue is indeed here formulated including also safety issues. Indeed, dimensioning the earth electrodes of their own secondary substations, distribution companies take into account the probable future configurations of the network due to transformations of overhead lines into cable lines or realization of new lines. On the contrary, they do not consider that, during normal working conditions. the structure of the network can be modified for long periods as a consequence of reconfiguration manoeuvres, with differences …

Metodologies competencials en la formació literària de mestres: experiències didàctiques per fomentar el pensament reflexiu: Competence-based methodo…

2023

L’objectiu d’aquest article és descriure i analitzar alguns projectes d’educació literària realitzats durant els últims vuit anys en el marc de la formació de docents per tal de reflexionar sobre la importància de l’ús de metodologies actives i competencials per l’ensenyament de la literatura al context universitari. Aquests projectes conformen experiències didàctiques com ara tallers d’escriptura, rutes literàries i l’ús dels videojocs per al foment lector. Presentem un comentari qualitatiu dels resultats d’aprenentatge més significatius i de la valoració dels estudiants a partir de la tria de diverses mostres. Finalment, arribem a la conclusió que aquestes experiències promouen no només l…

Validity and Reliability of a New Optoelectronic System for Measuring Active Range of Motion of Upper Limb Joints in Asymptomatic and Symptomatic Sub…

2019

The aim of this study was to evaluate the validity of the Veloflex infrared dynamic angle-meter (Veloflex-IDA) and the intra- and inter-rater reliability when measuring the ranges of motion (ROMs) of the upper limb joints. Thirty-five healthy and 20 symptomatic participants were evaluated. Twelve upper limb movements were measured in two sessions with the Veloflex-IDA, which is a device composed of a camera that tracks the trajectory of retro-reflective markers. In addition, a goniometer was used in the first session to evaluate concurrent validity. Validity and agreement were evaluated by Pearson correlation coefficient (r) and Bland&ndash

The link between violence and suicidal behavior among female university students in Spain

2019

Objective: To explore the association between violence and suicidal behavior in female university students. Method: A convenience sample of 540 female students enrolled in the Nursing and Teacher Training Faculties at the University of Valencia was selected. Violence by partners, nonpartners, and both was compared with suicidal thoughts and suicide attempts. An adjusted logistic regression and the Wald Test were performed to explore whether the effect on student's suicidal behavior differed if a partner or others committed violence. Results: 18.1% reported suicidal thoughts in the last month and 2.4% had attempted suicide in the past five years. Suicidal behavior was significantly higher in…

Physical Education Teachers’ Perceived Sexual and Physical Violence and Work-related Stress

2020

This study investigated the relationships between sexual (verbal and non-verbal sexual harassment) and physical violence against physical education (PE) teachers and work-related stress. Participants were 175 (females 122, males 53) Finnish PE teachers aged between 27 and 62 years. The findings showed that 1) higher perceived physical violence was positively associated with higher perceived non-verbal sexual harassment and work-related stress; 2) teachers with a sport science degree perceived higher work-related stress mediated by physical violence than other teachers; 3) longer-serving PE teachers reported lower verbal sexual harassment than teachers with less teaching experience; and 4) f…

2021

The present study was conducted with the aim of constructing and validating a short form of the Profile of Mood States (POMS). The POMS is a widely-applied measure for the assessment of an individual's mood. Thus, it is of great relevance for many research questions in clinical and social psychology. To develop the short scale, we first examined psychometric properties and found the optimal 16-item solution among all valid combinations of the full POMS in an exploratory subsample (n = 1,029) of our complete representative sample of the German general population. We then validated this model in a confirmatory subsample (n = 977). Additionally, we examined its invariance across age groups and…