Estrategias para la docencia en línea

Recurs d'aprenentatge de la Universitat Oberta de Catalunya.Recurso de aprendizaje de la "Universitat Oberta de Catalunya".Learning material of the "Universitat Oberta de Catalunya"

Dynamic response of a double-deck circular tunnel embedded in a full-space

© 2016. This version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/A three-dimensional dynamic model for calculating the ground-borne vibrations generated by harmonic loads applied on the interior floor of a double-deck circular tunnel is developed. The response of the system is obtained coupling the interior floor subsystem and the tunnel-soil subsystem in the wavenumber-frequency domain. The interior floor is modeled as a thin plate of infinite length in the train circulation direction and the tunnel-soil system is described using the Pipe in Pipe model. Some numerical instabilities of the resulting expressions are overcome by using analytic approximations. The results show that the dynamic behavior of the interior floor clearly influences the magnitude of the coupling loads acting on the tunnel structure. The soil response to a harmonic load acting on the double-deck tunnel is compared to the one obtained for the case of a simple tunnel finding significant differences between them for the whole range of frequencies studied. The proposed model extends the prediction of train-induced vibrations using computationally efficient models to this type of tunnel structure.Peer ReviewedPostprint (author's final draft

Using genetic algorithms to optimize the location of transducers for an active noise barrier

The effectiveness of an active noise barrier is heavily dependent on the positioning of secondary sources and error sensors. Typically, these components are located at the edge of the barrier; however, research suggests that alternative distributions may improve the performance of the active barrier. This paper utilizes a genetic optimizer to determine optimal transducer locations based on specific criteria. Two approaches are employed: the Two-step approach which, first identifies optimal control source positions and then seeks the best error microphone locations, and the Multi-parameter approach, which optimizes all active noise control parameters simultaneously. The acoustic fields of primary and secondary sources are analyzed for various numbers of control sources progressively increasing from 2 to 10 units. Results indicate that the Multi-parameter approach achieves higher outcomes and requires less computational effort. This approach is more desirable than the Two-step approach. The best configuration for the active noise barrier is determined to be control sources and error microphones placed at a height below the barrier’s edge and are distributed with an interval between a half and a full wavelength. The number of error sensors should be close to the number of secondary sources and both transducers should be placed at the farthest distance from the barrier surface, but oppositely. Furthermore, the study shows that when the primary noise source is close to the barrier adjacent transducers should not be spaced uniformlyThe author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was supported by the Agència de Gestió d’Ajuts Universitaris i de Recerca (2020 FI_B2 00073)Postprint (published version

Proper location of the transducers for an active noise barrier

The main intention of this study is to propose general criteria for the locations of the control sources and error microphones that improve the performance of the active noise barrier. Based on the proposed criteria of this study, the greater reduction is attained when the diffracted field of the noise source is canceled with the diffracted field of the control sources, that is, it is suggested to locate the control sources on the incident side and below the path that connects the furthest point in the shadow zone to the edge of the barrier. Furthermore, it is suggested that the error microphones are most suitably placed on the shadow side of the barrier where they are under the diffracted field of both the primary and control sources. The results also show that with these general criteria, the active noise control achieves an extra reduction that varies from 14.9 to 3.9 dB (for the third-octave band from 63 Hz to 1 kHz) and 9.3 dB for the broadband noisesPostprint (author's final draft

Evaluation of the effectiveness of control sources’ interval on active noise control performance

Amongst many important factors that affect the performance of active noise barrier, namely, the location of error microphones, and secondary sources, the intervals of adjacent error microphones and secondary sources, etc. this study focused on investigate the effect of secondary sources’ interval when they minimized the squared pressure at a set of 15 receivers located in the shadow zone of an infinite barrier. Three different positions around the top edge of barrier considered for secondary sources and best position which achieve the most reduction is selected. Also, the effect of ground reflections on the optimal secondary sources’ interval is investigated.Peer ReviewedPostprint (published version

Low-cost device for fault diagnosis in bearings based on the Hilbert-Huang transform

In order to monitor the condition of machinery complex industrial environments, high-cost equipment is required for signal acquisition and processing. However, low-cost sensor nodes with high processing capability are a potential solution to improve diagnostic systems. This paper presents a low-cost device for fault diagnosis based on the vibration response in rotating machines with the implementation of the Hilbert-Huang transform (HHT) analysis to extract the main characteristics of the signal. HHT, used to analyze non-linear and non-stationary signals, incorporates an Empirical Mode Decomposition (EMD) process. Processing is carried out in an embedded system to acquire vibration response data and extract signal characteristics that allow condition monitoring. As a result of local processing in the vibratory measurement device in an embedded system, the signal decomposition is performed, enabling the detection of the characteristic failure in the bearing ring and transmitting the alarm to a hub. This eliminates the need for a central diagnostic system and reduces the total cost of the system.This work has been carried out within the framework of the Looming Factory project, reference 001-P-001643, of the RIS3CAT program of the Generalitat de Catalunya. This research has been made possible thanks to the support of the MCIA Electronic Drives and Industrial Applications Research Group of the Universitat Politècnica de Catalunya and its collaborators.Peer ReviewedPostprint (published version

Los entornos 1x1 en Cataluña : entre las expectativas de las políticas educativas y las voces del profesorado

Este artículo presenta algunos de los resultados obtenidos en Cataluña en el proyecto de investigación Las políticas de un «ordenador por niño» en España: Visiones y prácticas del profesorado ante el programa Escuela 2.0. Un análisis comparado entre comunidades autónomas (EDU2010-17037). Financiado en el marco del Plan Nacional I+D+i del Ministerio de Ciencia e Innovación. Convocatoria 2010Este artículo tiene como finalidad aportar evidencias sobre cómo valora el profesorado de Cataluña los entornos 1x1, una implantación masiva de las tecnologías de la información y la comunicación en las aulas que suscita posicionamientos visiblemente polarizados entre los docentes. Comenzamos el trabajo abordando, brevemente, algunas de las constantes que arroja el análisis de casi 25 años de políticas TIC en Cataluña. Seguidamente, presentamos los proyectos autonómicos eduCAT1x1 y eduCAT 2.0, la concreción en Cataluña del programa Escuela 2.0. En la segunda parte del trabajo, analizamos cómo se posiciona el profesorado de Cataluña en el marco del proyecto TICSE 2.0 frente a los entornos 1x1, resituando las respuestas al cuestionario en línea en cuatro categorías: cambio metodológico, integración tecnológica, ordenadores en las aulas y contenidos digitales. Un análisis y una interpretación que ponen de manifiesto que las políticas (y las prácticas) relacionadas con los entornos 1x1 generan respuestas contundentes y posicionamientos categóricos entre el colectivo docente.Aquest article té com a finalitat aportar evidències sobre com valora el professorat de Catalunya els entorns 1x1, una implantació massiva de les tecnologies de la informació i la comunicació a les aules que suscita posicionaments visiblement polaritzats entre els docents. Comencem el treball abordant, breument, algunes de les constants que mostra l'anàlisi de gairebé 25 anys de polítiques TIC a Catalunya. Seguidament, presentem els projectes autonòmics eduCAT1x1 i eduCAT 2.0, la concreció a Catalunya del programa Escuela 2.0. A la segona part del treball, hi analitzem com es posiciona el professorat de Catalunya en el marc del projecte TICSE 2.0 enfront dels entorns 1x1, resituant les respostes al qüestionari en línia en quatre categories: canvi metodològic, integració tecnològica, ordinadors a les aules i continguts digitals. Una anàlisi i una interpretació que posen de manifest que les polítiques (i les pràctiques) relacionades amb els entorns 1x1 generen respostes contundents i posicionaments categòrics entre el col·lectiu docent.The aim of this article is to provide evidence on Catalonian teacher's perception about One Laptop Per Child. In fact, ICT massive integration in classrooms causes polarized opinions among teachers. This work is started with a brief revision of the most important/ common issues of almost 25 years of ICT policies in Catalonia. In the first part of the article, the regional concretions of the Spanish School 2.0 program (eduCAT1x1, eduCAT 2.0) are presented. In the framework of the Spanish research project TICSE 2.0, Catalonian teachers completed an online survey with closed and open-ended questions. In order to get evidence on Catalonian teachers' stance towards One Laptop Per Child, the openended responses of the survey were organized in four categories: methodological changes, ICT integration, computers in classrooms and digital contents. The analysis and interpretation of data gathered highlights teachers' forceful responses and strong positions on One Laptop Per Child

Avaluació dels aprenentatges en contextos educatius en línia

La cinquena publicació de la col·lecció tracta sobre l'avaluació dels aprenentatges en contextos educatius en líni

Mirroring learning ecologies of outstanding teachers to integrate ICTs in the classroom

This paper presents an exploratory study to examine the practices of outstanding primary school teachers in their professional development for ICT integration in teaching and learning, as a means of understanding how their learning ecologies develop and function. Outstanding teachers in the context of this study are teachers who innovate pedagogically and who are influential in the community, having successfully developed their learning ecology. Using a qualitative approach, we explore the concept of learning ecologies as a driver for innovation in the professional development of teachers, using a carefully selected sample of nine outstanding teachers. Drawing from in-depth interviews, specific coding and NVIVO analysis, our results show that these teachers develop organized systems for activities, relationships and resource usage and production, which can be characterized as the components of their professional learning ecology, to continuously keep up to date. We also identified some characteristics of teachers that perform outstandingly and factors that potentially facilitate or hinder their learning ecology development. Further research in the field will enable an improved understanding of the professional learning ecologies of school teachers and support future interventions and recommendations for professional development through the cultivation of emerging professional learning ecologies