ENPC

Champs-sur-Marne, France
Champs-sur-Marne, France
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Brunelle T.,Cirad | Coat M.,Agro ParisTech | Viguie V.,ENPC
OCL - Oilseeds and fats, Crops and Lipids | Year: 2017

This paper reviews the potential and barriers of demand-side mitigation options in the agricultural sector based on the recent academic literature and on a survey conducted on a sample of 788 respondents living in France. The mitigation potential of such measures as reducing losses in the food supply chain and shifting diets toward less animal products is estimated to be particularly high, higher, in particular, than supply-side mitigation options. However, to ensure that these measures do not entail a reduction in protein intake, these estimations should consider both caloric and protein units, and take into account the digestibility differentials between protein sources. Our survey shows that people are relatively reluctant to eat more sustainably, preferring to reduce their emissions in other areas such as housing or equipment. This relative reluctance is mainly due to individual perceptions linked to health concerns, taste or habits. Some obstacles could easily be overcome through well-designed policies aiming to, for example, advertise a lower consumption of red meat for health benefits. National governments are, however, rather inactive on this topic, leaving the initiative to the civil society. © 2017 T. Brunelle et al.


Cui K.,Southwest Jiaotong University | Defossez P.,French National Institute for Agricultural Research | Cui Y.-J.,ENPC | Richard G.,French National Institute for Agricultural Research
Geomechanics and Geotechnics: From Micro to Macro - Proceedings of the International Symposium on Geomechanics and Geotechnics: From Micro to Macro, IS-Shanghai 2010 | Year: 2011

Compressibility is closely related to the stability of geotechnical engineering structures made of compacted soils. Most analysis neglects the variation of suction during the compaction. A standard oedometer cell equipped with a tensiometer was used to measure soil suction continuously during the application of different vertical stresses. Measurements were carried out on remolded soil samples obtained by compacting a loamy soil sieved 2 mm and 0.4 mm at an initial dry density of 1.1 g cm -3 and at different initial water suctions. The results showed that the suction remained almost constant until a vertical stress threshold value beyond which the suction decreased as the stress increased. Furthermore, the results obtained highlighted the effect of soil structure on the stress threshold. Variations in soil suction were interpreted in term of processes at pore scale by comparing the evolution of pore-size distribution, measured by mercury intrusion, and the expected distribution of water in the pores. © 2011 Taylor & Francis Group.


Dormieux L.,E.N.P.C. | Jeannin L.,French Institute of Petroleum | Jeannin L.,GDF SUEZ | Bemer E.,French Institute of Petroleum | And 3 more authors.
International Journal for Numerical and Analytical Methods in Geomechanics | Year: 2010

In this paper, the strength of a sandstone is determined from a micromechanical approach. The microstructure of the rock is described as a porous polycrystal. A von Mises criterion is used for the strength of the solid grains. The grains are surrounded by Mohr-Coulomb interfaces describing the cement phase. The macroscopic strength of the polycrystal is determined by means of nonlinear homogenization techniques. The failure mechanism of the grains is assumed to be ductile. It is combined with a failure mechanism of the interfaces, which is successively assumed to be ductile and brittle. The theoretical predictions are then compared with the experimental data. Copyright © 2009 John Wiley & Sons, Ltd.


Schlosser F.,ENPC | Servant C.,Eiffage Travaux Publics | Guilloux A.,Terrasol | Bergere A.,Terrasol
Journal of Rock Mechanics and Geotechnical Engineering | Year: 2013

The Millau viaduct over the Tarn River is an exceptional bridge considering the height under the deck and the 2.5. km total length. Each of the seven high piers is founded on a thick raft setting on four large piles of 5. m in diameter and 10-15. m deep. The ground schematically consists of limestone in the north and of marls in the south. As the bridge is very sensitive to foundation settlements, the concessionary company decided to use the observational method for controlling the displacements and if necessary stabilize the foundations. The measurements show that the movements have remained small and admissible, particularly in terms of the rotations. The settlements have not occurred continuously under the load, but by steps. © 2013 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences.


Osselin F.,Laboratoire Navier | Fen-Chong T.,Laboratoire Navier | Fabbri A.,ENTPE | Dangla P.,Laboratoire Navier | And 2 more authors.
International Workshop on Geomechanics and Energy: The Ground as Energy Source and Storage | Year: 2013

The aim of this study is to evaluate the mechanical effects of the in-pore crystallization of salts during injection of supercritical carbon dioxide in the context of CCS. Isotropic linear poroelasticity modeling has been used to predict the macroscopic equivalent tensile stress in two cases: a REV linked to an infinite resrevoir of constant concentration, and an isolated REV subjected to an injection of dry supercritical carbon dioxide. Results show that crystallization pressure cannot be neglected while calculating the mechanical behavior of an aquifer during CCS.


Chevalier G.,ENPC | Le Ny J.,Ecole Polytechnique de Montréal | Malhame R.,Ecole Polytechnique de Montréal
Proceedings of the American Control Conference | Year: 2015

Studies of traffic dynamics rely either on macro-scopic models considering the traffic as a fluid, or on micro-scopic models of drivers' behavior. The connection between the microscopic and macroscopic scales is often done via empirical relationships such as the fundamental diagram for macroscopic models, relating traffic flow or average velocity and traffic density. In this paper, we consider a microscopic model consisting of a large number of rational, utility-maximizing drivers interacting on a single road. We then use the theory of Mean Field Games (MFG) to deduce a macroscopic model of traffic density emerging from these interactions. We show how to determine a microscopic utility function for the drivers compatible with standard empirical macroscopic fundamental diagrams. In addition to connecting the microscopic and macroscopic models analytically rather than empirically, our approach can offer additional flexibility to model drivers at the macroscopic level, using a Hamilton-Jacobi-Bellman equation coupled with the standard conservation law for the vehicles. © 2015 American Automatic Control Council.


Leger R.,ONERA | Peyret C.,ONERA | Piperno S.,ENPC
16th AIAA/CEAS Aeroacoustics Conference (31st AIAA Aeroacoustics Conference) | Year: 2010

We focus on the study of a coupling algorithm applied to direct acoustic waves simulation. The idea is to introduce a partition of the computational domain, and to be able to use meshing techniques and numerical methods of different natures in order to meet the local requirements of the computation. Here, we solve the Linearized Euler Equations and couple a Discontinuous Galerkin method (DGM) running on an unstructured mesh and a Finite Difference method (FDM), running on a Cartesian grid. The aim is to take into account complex geometries by running a DGM and run a FDM away from the obstacles to reduce computational cost. In this paper, we present a DG/FD coupling algorithm and discuss some preliminary validation elements. © 2010 by Raphaël Léger.


Roche S.,Ecole Polytechnique Federale de Lausanne | Mattoni G.,ENPC | Weinand Y.,Ecole Polytechnique Federale de Lausanne
IABSE Conference, Nara 2015: Elegance in Structures - Report | Year: 2015

Folded plate structures propose an efficient design employing thin Laminated Veneer Lumber panels. Inspired by the Japanese furniture joining technique, the Multiple Tab-and-Slot Joint was developed for multi-assembly of timber panels with non-parallel edges, as a solution requiring no adhesive or metal joints. As the global analysis of our origami structures reveals that the rotational stiffness at ridges affects the global behaviour, we propose an experimental and numerical study of this linear interlocking connection. Its geometry is governed by three angles that orient the contact faces. Nine combinations of these angles were tested with two different bending set-ups: closing or opening the fold formed by two panels and measuring the rotational slip. The non-linear behaviour has been conjointly reproduced numerically using the finite element method and the continuum damage mechanic.

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