Comment développer l'utilisation de grilles critériées (rubrics) dans les apprentissages ?

National audienceContrairement aux évaluations sommatives qui mesurent la performance de l'apprenant, les évaluations critériées sont centrées sur le processus d'apprentissage et son amélioration. La conception de telles grilles critériées reste néanmoins complexe. Nous proposons dans cet article un début de taxonomie de grilles critériées visant à aider les enseignants dans l'appropriation de ces outils

Enhancement of electrostrictive polymer efficiency for energy harvesting with cellular polypropylene electrets

The purpose of this paper is to propose new means for harvesting energy using electrostrictive polymers. The recent development of electrostrictive polymers has generated new opportunities for high-strain actuators. At the current time, the investigation of using electrostrictive polymer for energy harvesting, or mechanical-to-electrical energy conversion, is beginning to show its potential for this application. The objective of this work was to study the effect of cellular polypropylene electrets after high-voltage corona poling on an electrostrictive polyurethane composite filled with 1 vol.% carbon black at a low applied voltage in order to increase the efficiency of the electromechanical conversion with electrostrictive polymers. Theoretical analysis supported by experimental investigations showed that an energy harvesting with this structure rendered it possible to obtain harvested power up to 13.93 nW using a low electric field of 0.4 V/mu m and a transverse strain of 3% at a mechanical frequency of 15 Hz. This represents an efficiency of 78.14% at low frequency. This percentage is very significant compared to other structures. Finally, it was found that the use of polypropylene electrets with electrostrictive polymers was the best way to decrease the power of polarization in order to obtain a good efficiency of the electromechanical conversion for energy harvesting

Mechanical characterization of an electrostrictive polymer for actuation and energy harvesting

Electroactive polymers have been widely used as smart material for actuators in recent years. Electromechanical applications are currently focused on energy harvesting and actuation, including the development of wireless portable electronic equipment autonomous and specific actuators such as artificial muscles. The problem to be solved is to make its devices the most efficient, as possible in terms of harvested energy and action. These two criteria are controlled by the permittivity of the electrostrictive polymer used, the Young\u27s modulus, and their dependence on frequency and level of stress. In the present paper, we presented a model describing the mechanical behaviour of electrostrictive polymers with taking into account the mechanical losses. Young\u27s modulus follows a linear function of strain and stress. However, when the elongation becomes higher, the data obtained from this strain linear trend and significant hysteresis loops appear the reflections on the existence of mechanical losses. In this work, to provide the analysis of the experimental observations, we utilized a theoretical model in order to define a constitutive law implying a representative relationship between stress and strain. After detailing this theoretical model, the simulation results are compared with experimental ones. The results show that hysteresis loss increases with the increase of frequency and strain amplitude. The model used here is in good agreement with the experimental results

Alien Registration- Guyomar, Louise Marie J. (Saint Agatha, Aroostook County)

https://digitalmaine.com/alien_docs/33224/thumbnail.jp

Power processing circuits for electromagnetic, electrostatic and piezoelectric inertial energy scavengers

Accepted versio

"La sensación de la soledad" en las Rimas de Bécquer (Aproximación a la poesía metafísica)

In our article we try to approximate to the topic of Spanish romanticism and the cosmovision of Gustavo Adolfo Bécquer in particular. We evaluate the role of universal romantic symptom – the feeling of loneliness in Bécquer’s Rimas and observe how his poetic world is linked to the existensial vision of Miguel de Unamuno.En nuestro artículo intentamos acercarnos al tema del romanticismo español, y a la visión romántica de Gustavo Adolfo Bécquer en particular. Dentro de ello investigamos el papel del síntoma universal del romanticismo – la sensación de la soledad en las Rimas de Bécquer y observamos cómo está vinculado su mundo romántico con la visión existencialista de Miguel de Unamuno