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Saint-Sauveur-en-Rue, France

Yates M.L.,University Paris Est Creteil | Yates M.L.,Center for Studies and Expertise on Risks | Benoit M.,University Paris Est Creteil | Benoit M.,Electricite de France
International Journal for Numerical Methods in Fluids

Summary: The accuracy and efficiency of two methods of resolving the exact potential flow problem for nonlinear waves are compared using three different one horizontal dimension (1DH) test cases. The two model approaches use high-order finite difference schemes in the horizontal dimension and differ in the resolution of the vertical dimension. The first model uses high-order finite difference schemes also in the vertical, while the second model applies a spectral approach. The convergence, accuracy, and efficiency of the two models are demonstrated as a function of the temporal, horizontal, and vertical resolutions for the following: (1) the propagation of regular nonlinear waves in a periodic domain; (2) the motion of nonlinear standing waves in a domain with fully reflective boundaries; and (3) the propagation and shoaling of a train of waves on a slope. The spectral model approach converges more rapidly as a function of the vertical resolution. In addition, with equivalent vertical resolution, the spectral model approach shows enhanced accuracy and efficiency in the parameter range used for practical model applications. © 2015 John Wiley & Sons, Ltd. Source

Lopes M.,University of Sao Paulo | Gabet T.,University | Bernucci L.,University of Sao Paulo | Mouillet V.,Center for Studies and Expertise on Risks
Materials and Structures/Materiaux et Constructions

Within the framework of a sustainable development, manufacturing bituminous mixtures while reducing energy and using less new aggregates and new bitumen may be considered as an important topic, according to the quantities of asphalts mixtures produced for creating and maintaining road networks. This work aims to study the interest and the potential problems when coupling the warm mix asphalt technology (WMA) and the use of high ratio of reclaimed asphalt pavement (RAP) in the mixture. Initially, a study on managing RAP is performed, aiming to show that separating RAP aggregates in several fractions leads to a higher control of RAP in terms of homogeneity. Homogeneity of RAP is a key point for increasing recycling rates. The present study coupling WMA and RAP is based on the French design method for manufacturing asphalt concretes, which includes gyratory compaction tests, French wheel tracking tests, complex modulus tests and fatigue tests. However, the French design method does not take into account the physical and chemical aging of bituminous mixtures with time. As we consider that coupling WMA and RAP may lead to aging problems, it was decided to use an aging process before performing the standard tests. The results show that a WMA containing a high ratio of RAP has good performances according to the standard relative to this material, whatever the test. However, this material tends to be more sensitive to fatigue than hot and warm mixes without RAP. © 2014 RILEM Source

Othmen I.,Institut Universitaire de France | Othmen I.,French Environment and Energy Management Agency | Poullain P.,Institut Universitaire de France | Caucheteux A.,Center for Studies and Expertise on Risks | Leklou N.,Institut Universitaire de France
WIT Transactions on Engineering Sciences

The concerns regarding sustainable development bring to light the importance of the consumption of natural energy resources by the building sector. The thermal renovation of old buildings should be a priority for reducing greenhouse gas emission. In fact, tuffeau, the main stone of Loire Valley, France, is a very porous limestone (43%) and seems to be very sensitive to atmospheric conditions. So, an inappropriate insulation technique can lead to moisture disorders harmful to the sustainability of the wall. Its compatibility with an insulation material can be numerically studied using a combined heat and moisture transfer model. One of the most important aspects on modeling is the knowledge of the material properties. The numerical tool WUFI based on Künzel model leads to identify the parameters whose measurement effort must be intensified as a result of a local sensitivity analysis. Those parameters are adsorption isotherm and convective coefficients in the case of static conditions. © 2014 WIT Press. Source

Cerezo V.,French Institute of Science and Technology for Transport | Gerthoffert J.,Civil Aviation Technical Center | Bouteldja M.,Center for Studies and Expertise on Risks | Do M.T.,French Institute of Science and Technology for Transport
Journal of Aircraft

Aircraft performances at landing or takeoff depend strongly on runway surface conditions. There is a need to provide aircraft pilots with reliable information in view of determining landing performance. Currently, this information is based on a description of the type and depth of contaminants on the runway surface. This paper presents a new method to improve the correlation between friction coefficients and braking coefficients measured respectively by ground vehicles and aircraft. A three-step approach is proposed, using a friction model developed by the Engineering Sciences Data Unit (ESDU), to weight the measured coefficients by factors taking into account the characteristics of the devices and the contaminants. The friction ESDU model is used on contaminated surfaces. The methodology is applied to data collected from extensive friction tests conducted between 1996 and 2003 (in the Joint Winter Runaway Friction Measurement Program). Characteristics ofground friction measuring devices and aircraft are provided as inputs for the ESDU model. It was found that the correlation between weighted ground friction and braking coefficients is improved significantly compared with the correlation between unweighted coefficients. Advantages of the newly proposed method are discussed in terms of using ground friction coefficients as a promising alternative to determine the runway condition code for aircraft pilots. Copyright © 2015 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved. Source

Asfour S.,Center for Studies and Expertise on Risks | Bernardin F.,Center for Studies and Expertise on Risks | Toussaint E.,University of Auvergne | Piau J.-M.,French Institute of Science and Technology for Transport
Applied Thermal Engineering

Melting snow or de-icing with a hydronic system may be employed for some critical roads sections particulary sensitive to winter conditions (turns zone, highways upslope or downslope, bridges, etc.) in order to avoid dangerous driving conditions caused by snow or ice. This article presents a hydronic heating system that circulates a heated fluid through a bonding porous asphalt layer, to prevent ice formation at the road surface. In this article, we study the heat exchange between fluid and road. Firstly a 2D thermo-hydraulic model is developed in order to determinate the temperature field in the pavement structure when the fluid circulates in the porous bonding layer. Secondly, the sensibility of the temperature distribution at the road surface is studied to identify the most relevant model parameters. Finally, the evolution of the minimum temperature of the injected fluid with different flow rate is determined in order to keep positive the road surface temperature at any point for given meteorological data. © 2016 Elsevier Ltd Source

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