A cylindrical self-consistent modelling of vegetal wools thermal conductivity

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Gestion du risque ou gestion de l'environnement? Le cas des massifs du Diois et des Baronnies, Préalpes du Sud, France

[Departement_IRSTEA]Eaux [TR1_IRSTEA]RIVAGENational audienceCet article propose de montrer comment la gestion institutionnalisée « sécuritaire » des zones d'érosion en montagne, telle qu'elle a été conduite depuis plus d'un siècle sous le cadre législatif de la Restauration des Terrains en Montagne (RTM), évolue aujourd'hui à la suite de la mise en ½uvre de nouveaux principes de gestion «environnementale », fondée sur la notion de restauration d'une recharge sédimentaire durable des hydrosystèmes fluviaux. Notre objectif est de présenter, à travers l'exemple de 3 bassins versants des Préalpes du Sud (Drôme, Eygues et Roubion), comment l'émergence de risques nouveaux dans la plaine (raréfaction de la ressource en eaux, risque d'inondation accru, risque de destruction d'ouvrages) influence les stratégies de gestion des versants et la perception qu'en ont les acteurs. Cette étude de cas montre également combien la perception du bassin versant, territoire de nature hydro-géomorphologique, est prépondérante depuis plus d'un siècle dans la gestion du risque en montagne

A self-consistent approach for the acoustical modeling of vegetal wools

Vegetal wools have the capacity to store atmospheric carbon dioxyde, one of the main gases responsible for climate change. So, these insulating materials are used as key elements for green buildings. Moreover, vegetal wools present high sound absorption level performances contributing to the acoustic comfort of indoor living spaces. These properties are directly related to the morphology and the size of their vegetal fibres. Thus, to take their microstructural specificities into account for the modeling of their sound absorption properties, a micro-macro homogenization approach based on a cylindrical geometry is developed. This modeling method, based on a mix between Homogenization of Periodic Media (HPM) and Self-Consistent Method (SCM), is called SCMcyl. The macroscopic behaviour laws of materials are rigorously obtained by using HPM. Then, the SCM leads to the establishment of two possible analytical solutions (a velocity approach v and a pressure approach p) under the fundamental assumption of the energy equivalence between a generic cylindrical inclusion, representative of the vegetal wools physical and geometrical properties at microscopic scale, and the homogeneous equivalent medium at the macroscopic scale. The two modeling approaches developed in this paper, SCMcyl-v and SCMcyl-p, can be used to determine the sound absorption of fibrous materials using only two parameters, an equivalent fibre radius value and the material porosity. Finally, these solutions are validated for the vegetal wools case by comparison with experimental measurements

Acoustical and thermal self-consistent modelling for the optimisation of vegetal wools used in green buildings

3rd International Conference on Bio-Based Building Materials ICBBM 2019, BELFAST, ROYAUME-UNI, 26-/06/2019 - 28/06/2019Vegetal wools are biobased insulators that contribute to green buildings development. In order to optimize both their acoustical and thermal performances, a joint modelling method relating microstructural parameters to materials macroscopic properties is developed