La «demande sociale», notion évidente ou à déchiffrer

Pose trois questions : le rapport à établir entre activités et pratiques sociales, les modes de régulation existant sur les «espaces naturels», et la prise en charge de la fréquentation et des organisations vers les propriétaires et les gestionnaires des lieux

Sur nos besoins de nature : l'exemple du massif des Calanques.

Histoire des relations humaines avec le massif des Calanques : cabanon, chasse, randonnée, jogging, etc... Analyse sociologique des rapports entre ces différentes activités et sur leur perception par leur public

Un nombre croissant de propriétaires sont prêts à ouvrir leur forêt au public

Une enquête réalisée dans le Var permet d'identifier les principaux freins des propriétaires concernant l'ouverture de leur forêt au public. Elle révèle également qu'un bon nombre de propriétaires sont demandeurs de propositions opérationnelles

Un nombre croissant de propriétaires sont prêts à ouvrir leur forêt au public

International audienceUne enquête réalisée dans le Var permet d'identifier les principaux freins des propriétaires concernant l'ouverture de leur forêt au public. Elle révèle également qu'un bon nombre de propriétaires sont demandeurs de propositions opérationnelles

An incremental model to assess the environmental impact of cap cover systems on MSW landfill emissions

International audienceLandfill cap covers are designed to contain fugitive methane emissions and to prevent uncontrolled leachate infiltration. The objective of this paper is to propose a method for assessing their impact on the mitigation of landfill greenhouse gas emissions using a new dedicated model (IMAGE-Landfill) that takes into account the different steps of landfill management history as well as the incremental methane production from the different cells. In particular, different collection and oxidation efficiencies are considered depending on the landfill operation, on its life step and on the chosen cap cover system. Two different theoretical single cell case studies and one real-scale landfill were used to calibrate the IMAGE-Landfill model. The results highlight that, depending on the selected cap cover lining system, the potential greenhouse gas emissions may be divided by a factor 2.5-7, even if no energy is recovered from the collected methane. This model is a useful tool for landfill operators to model methane production, but also to select the most appropriate cover type for each step of the landfill lifetime. Finally, this research appeals for a better consideration of environmental impacts when designing landfill barriers

Experimental analysis of linear vibration absorbers for an uncertain main structure.

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Vibro-Impact NES: A Correlation Between Experimental Investigation and Analytical Description

International audienceIn this work the dynamics of a Vibro-Impact Nonlinear Energy Sink (VI-NES) is experimentally investigated via a harmonically forced single-degree-of- freedom linear oscillator (LO) to which a VI-NES is attached. Depending on external force amplitude and frequency, either a Strongly Modulated Response (SMR) or a constant amplitude response (CAR) is observed. In both cases an irreversible transfer of energy occurs from the LO towards the VI-NES: process known as passive Targeted Energy Transfer(TET). Furthermore, the problem is analytically studied by using the multiple scales method. For the fast and the slow time scales the Slow Invariant Manifold (SIM) is obtained. The 0-order SIM shows the existence of a stable and an unstable branch of solution, and of an energy threshold (a saddle-node bifurcation) for the solutions to appear. Subsequently the 1-order SIM is calculated to find the fixed points of the problem. When a stable fixed point exists, the system is naturally drawn to it and a CAR is reached. Otherwise a SMR state is established and no stable point is attained. Finally a good agreement between experimental and analytical results is shown

Performance comparison between a nonlinear energy sink and a linear tuned vibration absorber for broadband control

The performance of a linear tuned vibration absorber (LTVA) and a nonlinear energy sink (NES) for the vibration mitigation of an uncertain linear primary system is investigated. An analytic tuning rule for the LTVA when the primary system contains uncertainty is derived. The behavior of the linear system coupled to the NES is analyzed theoretically. A tuning methodology for the NES in the deterministic as well as for the uncertain case is presented. © The Society for Experimental Mechanics, Inc. 2016

Recherche sur le comportement de l'interface "géomembrane - structure support ou structure de couverture"

The objective of this experiment is to know better the mechanical behavior of geomembranes used in waste storage centers inside geomembrane tightness devices in order to improve the sizing of these devices. The tests have contributed to the definition of two standards, provided numerous results and brought more information on the resistance of geomembranes to friction. This research has also led to equipment improvement. These works must be validated on real cases with anchorage strength measurements. / La recherche effectuée vise à mieux connaître le comportement mécanique des géomembranes utilisées dans les centres de stockage de déchets au sein des dispositifs d'étanchéité par géomembrane (DEG), l'objectif poursuivi étant d'améliorer le dimensionnement de ces dispositifs. Les essais réalisés ont contribué à l'élaboration de deux normes, fourni de nombreux résultats et apporté une meilleure connaissance de la résistance au frottement des géomembranes ; la recherche a également conduit à l'amélioration de plusieurs appareillages. La validation de ces travaux reste à confirmer sur des cas réels instrumentés comportant en particulier des mesures de forces d'ancrage