53 research outputs found

    An脿lisi de les qualificacions obtingudes amb una estrategia docent ludificada. Cas pr脿ctic en assignatures de l鈥櫭爉bit de l鈥檈nginyeria mec脿nica

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    Es presenta l鈥榓n脿lisi de la correlaci贸 entre les qualificacions de proves avaluadores tradicionals i les obtingudes amb q眉estionaris ludificats. S鈥檋a desenvolupat un m猫tode per obtenir de forma automatitzada unes qualificacions amb diferents criteris de ponderaci贸 (penalitzaci贸 de les respostes incorrectes, segons el temps de resposta i la normalitzaci贸 de les qualificacions). Els resultats mostren correlacions significatives que suggereixen l鈥櫭簊 de les activitats ludificades en l鈥檃valuaci贸 sumativa.Peer ReviewedObjectius de Desenvolupament Sostenible::4 - Educaci贸 de QualitatPostprint (published version

    An谩lisis de las calificaciones en actividades ludificadas

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    Desde hace unos a帽os se ha extendido el uso de estrategias docentes donde se utiliza la ludificaci贸n mediante sistemas personales de respuesta en directo en el aula. Diferentes autores han contrastado las ventajas del uso de estas herramientas en el proceso de ense帽anza aprendizaje, pero hay discrepancias en el uso de las calificaciones obtenidas en las actividades ludificadas. Algunos autores sostienen que las calificaciones obtenidas en estas actividades ludificadas s贸lo deben formar parte de la evaluaci贸n formativa y no formar parte de la evaluaci贸n sumativa. No obstante, los autores de este trabajo, en las fases iniciales de su investigaci贸n observaron una correlaci贸n significativa entre las calificaciones obtenidas en los cuestionarios ludificados via Kahoot! y las calificaciones obtenidas en el resto de las pruebas realizadas como ex谩menes y las calificaciones obtenidas en la asignatura. Las calificaciones que se pueden obtener de Kahoot! no sirven para extraer directamente una calificaci贸n num茅rica para cada usuario en una escala acotada (rango de 0 a 10 puntos). Para comparar los resultados de la ludificaci贸n con el resto de elementos de evaluaci贸n, se ha desarrollado un sistema automatizado de obtenci贸n de las calificaciones en un rango de 0 a 10 puntos. Estas calificaciones difieren entre ellas dependiendo de los criterios de ponderaci贸n: penalizaci贸n de las respuestas incorrectas, tiempo de respuesta y normalizaci贸n de las notas entre el grupo clase. Los resultados que se obtienen son los coeficientes de correlaci贸n entre los cuestionarios Kahoot! y el resto de elementos evaluadores, los p-valores correspondientes y una representaci贸n visual de estas correlaciones. El principal resultado del an谩lisis estad铆stico es que en funci贸n de la metodolog铆a de la asignatura y el enfoque de los cuestionarios ludificados hay una correlaci贸n significativa entre las calificaciones obtenidas en los cuestionarios ludificados y los sistemas de evaluaci贸n tradicional. Adem谩s, se ha creado un sistema de puntuaci贸n en funci贸n del porcentaje de aciertos del grupo clase, que permite evaluar la calidad de las preguntas de los cuestionarios, clasificar la dificultad del cuestionario y as铆 poder diferenciarlos seg煤n este criterio para el an谩lisis con el resto de elementos evaluadores.Peer ReviewedPostprint (published version

    Controlled composite processing based on off-stoichiometric thiol-epoxy dual-curing systems with sequential heat release (SHR)

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    Control of curing rate and exothermicity during processing of thermosetting composite materials is essential in order to minimize the formation of internal stresses leading to mechanical and dimensional defects in the samples, especially in thick composite samples. It was recently proposed that sequential heat release, an approach based on the kinetic control of the curing sequence of dual-curing thermosets, would enable a step-wise release of the reaction heat and therefore a better control of conversion and temperature profiles during the crosslinking stage. In this article, it is shown experimental proof of this concept obtained by means of an instrumented mold that can be used for the processing of small samples with and without carbon fiber reinforcement. Safe processing scenarios have been defined by numerical simulation using a simplified two-dimensional heat transfer model and validated experimentally.Peer ReviewedPostprint (author's final draft

    New epoxy thermosets derived from clove oil prepared by epoxy-amine curing

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    New thermosets from a triglycidyl eugenol derivative (3EPOEU) as a renewable epoxy monomer were obtained by an epoxy-amine curing process. A commercially-available Jeffamine庐 and isophorone diamine, both obtained from renewable resources, were used as crosslinking agents, and the materials obtained were compared with those obtained from a standard diglycidylether of bisphenol A (DGEBA). The evolution of the curing process was studied by differential scanning calorimetry and the materials obtained were characterized by means of calorimetry, thermogravimetry, thermodynamomechanical analysis, stress鈥搒train tests and microindentation. 3EPOEU formulations were slightly less reactive, and the thermosets obtained showed higher Tgs than those prepared from DGEBA, since they had higher crosslinking density than formulations with DGEBA because of the more compact structure and higher functionality of the eugenol derivative. 3EPOEU thermosets showed good thermal stability and mechanical properties. The results obtained in this study allow us to conclude that the triglycidyl derivative of eugenol, 3EPOEU, is a safe and environmentally friendly alternative to DGEBA.Postprint (published version

    Hard epoxy thermosets obtained via two sequential epoxy-amine condensations

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    A new family of dual-curable poly(脽-hydroxyamine ether) thermosets based on amine-epoxy formulations has been prepared and characterized. Both curing stages consist in an epoxy-amine polycondensation, each having different reactivity. Whereas the first one is carried out at relatively low temperature using an aliphatic flexible amine, the second is carried out at high temperature with a rigid aromatic amine. The sequentiality of the curing and the stability of the intermediate materials can be established in the basis of the different nucleophilicity of the amines used. The aromatic amine, with a weakly nucleophilic character, is not able to react with epoxides during the first stage at low temperature. The intermediate and final materials exhibit a wide range of properties, thanks to the different glass transition of both epoxy-amine networks, and can be tuned by changing the relative proportion of both diamines in the formulation. The participation of the epoxy resin in both curing stages ensures the homogeneity of the prepared materials, rendering them excellent candidates for applications such as adhesives or smart materials.Postprint (author's final draft

    Thermal conductive composites prepared by addition of several ceramic fillers to thermally cationic curing cycloaliphatic epoxy resins

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    Novel composite coatings prepared from3,4-epoxy cyclohexylmethyl 3,4-epoxycyclohexane carboxylate (ECC) and different ceramic fillers have been prepared to improve the thermal dissipation of electronic devices. As latent cationic initiator, a benzylanilinium salt with triethanolamine has been used, which leads to a polyether matrix. Different proportions of Al2O3, AlN and SiC as fillers were added to the reactive formulation. The effect of the fillers selected and their proportions on the evolution of the curing was studied by calorimetry and rheometry. The thermal conductivity, thermal stability, thermal expansion coefficient and thermomechanical and mechanical properties of the composites were evaluated. An improvement of 820% in thermal conductivity in reference to the neat material was reached with a 75 wt % of AlN, whereas glass transition temperatures higher than 200 C were determined in all the composites

    Click-based dual-curing thermosets and their applications

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    Dual curing is the methodology for obtaining thermosets by combining two different and compatible polymerization reactions, taking place sequentially or simultaneously. Sequential dual-curing processing enables the preparation of handleable materials after a first stage of curing that, upon application of a second stimulus, further cross-link to achieve the ultimate properties. Controlled curing sequences can be achieved by means of using latent catalysts that are activated upon irradiation or temperature, or else by thermal control of the reaction kinetics. Many possible combinations of reactions are possible, especially those including click-type polymerization reactions, which are especially suited because of their efficiency, selectivity, and orthogonality. Careful choice of the polymerization reactions, monomer composition, and structure makes it possible to obtain intermediate materials with well-defined rheological, thermal, and mechanical properties, ranging from those of viscoelastic liquids to lightly cross-linked rubbers or glassy cross-linked networks. After the second curing stage, the materials complete the cross-linking process and reach the ultimate properties required for the end use of the material. This unique combination of features represents significant advantages in terms of processing flexibility, facilitating manufacturing, and assembly in comparison with curing systems based on a single polymerization reaction and opens new application perspectives in diverse areas such as photopatterning, holography, shape-memory devices, or microfluidics

    An谩lisis de la retroalimentaci贸n gamificada en tiempo real. Caso pr谩ctico en asignaturas de ingenier铆a mec谩nica

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    Las herramientas de gamificaci贸n son una metodolog铆a pedag贸gica que, aplicada a la ense帽anza, pretende que el alumnado profundice en los contenidos o competencias deseados a trav茅s de un juego o competici贸n. Entre estas herramientas de gamificaci贸n existen diversas actividades elearning que permiten mejorar el proceso de ense帽anza/aprendizaje aumentando simult谩neamente el inter茅s del alumnado. La actuaci贸n que se plantea introduce una retroalimentaci贸n en tiempo real mediante t茅cnicas de gamificaci贸n utilizando la respuesta en directo con tel茅fonos m贸viles a preguntas realizadas en el aula. Con esta finalidad, se ha implementado una estrategia blended learning donde se han combinado las metodolog铆as tradicionales con la gamificaci贸n. En concreto, utilizando los cuestionarios de la aplicaci贸n Kahoot!, se quiere ver la idoneidad de estas t茅cnicas tanto en grupos grandes (en clases magistrales) como en grupos peque帽os (laboratorios). La acci贸n se ha llevado a cabo en dos asignaturas: en las clases magistrales de la asignatura de Tecnolog铆a Mec谩nica de tercer curso del Grado en Ingenier铆a Mec谩nica impartido en la Universitat Rovira i Virgili, y en las pr谩cticas de laboratorio en la asignatura Teor铆a de M谩quinas y Mecanismos de segundo curso del Grado en Tecnolog铆as Industriales impartido en la Escuela T茅cnica Superior de Ingenier铆a Industrial de Barcelona de la Univerisitat Polit猫cnica de Catalunya. Para analizar la mejora introducida se han evaluado diferentes elementos: los resultados acad茅micos, una encuesta de satisfacci贸n al alumnado y un estudio de la correlaci贸n entre las calificaciones obtenidas en los cuestionarios Kahoot! y las calificaciones obtenidas en los ex谩menes. En ambas asignaturas se ha comprobado que la gamificaci贸n estimula el inter茅s del alumnado y ayuda a adquirir los conocimientos de la materia por medio de las herramientas t铆picas de un juego. Los resultados muestran una mejora de los indicadores de las asignaturas (la tasa de rendimiento) as铆 como la mejora de la satisfacci贸n del alumnado con la asignatura. Tambi茅n se ha demostrado mediante el estudio estad铆stico una correlaci贸n significativa entre las calificaciones obtenidas en los cuestionarios gamificados y las calificaciones obtenidas en los ex谩menes. De esta forma, la retroalimentaci贸n ha permitido al alumnado tener indicadores v谩lidos para gestionar su proceso de aprendizaje. Adem谩s, la retroalimentaci贸n tambi茅n ha permitido verificar la efectividad del mensaje expuesto en cada clase y detectar si existen carencias en algunas sesiones.Peer ReviewedPostprint (author's final draft

    Thermoconductive thermosetting composites based on boron nitride fillers and thiol-epoxy matrices

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    In this work, the effect of the addition of boron nitride (BN) fillers in a thiol-cycloaliphatic epoxy formulation has been investigated. Calorimetric studies put into evidence that the kinetics of the curing has been scarcely affected and that the addition of particles does not affect the final structure of the network. Rheologic studies have shown the increase in the viscoelastic properties on adding the filler and allow the percolation threshold to be calculated, which was found to be 35.5%. The use of BN agglomerates of bigger size increases notably the viscosity of the formulation. Glass transition temperatures are not affected by the filler added, but Young鈥檚 modulus and hardness have been notably enhanced. Thermal conductivity of the composites prepared shows a linear increase with the proportion of BN particle sheets added, reaching a maximum of 0.97 W/K路m. The addition of 80 碌m agglomerates, allowed to increase this value until 1.75 W/K路m

    Laboratory 3.0: manufacturing technologies laboratory virtualization with a student-centred methodology

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    This paper presents a blended-learning strategy for improving the teaching method applied in the laboratory subject Manufacturing Technologies. The teaching method has been changed from a predominantly teacher-centred to an active learning system with a student-centred focus and e-learning activities. In face-to-face classes, a game-based learning platform has been used. This methodology ensured engaging classes at the same time that provided a useful live feedback for students and teachers. The virtualization of the laboratory was achieved by two different e-learning activities, self-assessment tasks and video clips. These e-learning tools have been used not only to improve the students鈥 learning but also to enhance their motivation. The results from academic outputs show a significant improvement after the new blended learning method is applied. Moreover, a student satisfaction survey shows the positive impact of the methodology on the students鈥 engagement and motivationPeer Reviewe
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