Thermally activated resonant grating using a vanadium dioxide waveguide

International audienceIn this work, we report on the design of a one-dimensional subwavelength resonant grating comprised of a fused silica substrate and a bi-layer waveguide, consisting of a solgel synthetized anatase TiO 2 layer followed by a thin VO 2 layer that is applied using pulsed laser deposition and rapid thermal annealing. A TE waveguide mode is excited under normal incidence in the VO 2 /TiO 2 bi-layer via a positive photoresist based grating printed on top, leading to high resonant reflection at room temperature. Increasing the temperature to about 68°C causes the VO 2 to undergo a dielectric to metallic transition accompanied by optical modifications in the IR region, canceling the resonance effect. This thermally triggered absorber/emitter tunable configuration enabling the on and off switching of optical resonant excitation in a reversible manner is proposed for passive Q-switching self-protecting devices for high power lasers in the IR wavelength range. Modeling of the optimized temperature dependent resonant waveguide and preliminary experimental results are presented

NF EN ISO 10776. Géotextiles et produits apprentés : Détermination des caractéristiques de perméabilité de l'eau, perpendiculairement au plan et sous contrainte

Norm

NF EN ISO 10772. Géotextiles - Méthode d'essai pour la détermination du comportement en filtration des géotextiles en régime d'écoulement turbulent

NormeLa présente Norme internationale décrit une méthode d'essai permettant de déterminer le sol passant à travers un filtre géotextile, lorsqu'il est exposé à un régime d'écoulement turbulent externe. L'essai fournit une valeur pour un type de sol comme essai de performance pour la conception de couches de protection contre l'érosion avec filtres géotextiles, dans les applications en ingénierie hydraulique

The 50 most important questions relating to the maintenance and restoration of an ecological continuum in the European Alps

The European Alps harbour a unique and species-rich biodiversity, which is increasingly impacted by habitat fragmentation through land-use changes, urbanization and expanding transport infrastructure. In this study, we identified the 50 most important questions relating to the maintenance and restoration of an ecological continuum - the connectedness of ecological processes across many scales including trophic relationship and disturbance processes and hydro-ecological flows in the European Alps. We initiated and implemented a trans-national priority setting exercise, inviting 48 institutions including researchers, conservation practitioners, NGOs, policymakers and administrators from the Alpine region. The exercise was composed of an initial call for pertinent questions, a first online evaluation of the received questions and a final discussion and selection process during a joint workshop. The participating institutions generated 484 initial questions, which were condensed to the 50 most important questions by 16 workshop participants. We suggest new approaches in tackling the issue of an ecological continuum in the Alps by analysing and classifying the characteristics of the resulting questions in a non-prioritized form as well as in a visual conceptualisation of the inter-dependencies among these questions. This priority setting exercise will support research and funding institutions in channelling their capacities and resources towards questions that need to be urgently addressed in order to facilitate significant progress in biodiversity conservation in the European Alps