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Chrenko D.,CNRS Research Department of Automotive Engineering | Chrenko D.,University of Technology of Belfort - Montbeliard
IET Intelligent Transport Systems

This study covers three main aspects. First, it presents a way to create driving cycles using only driver behaviour (acceleration, deceleration and maximum speed) and route data as input parameters. Second, a power-based approach to describe different vehicle architectures from internal combustion engine vehicle, over stop and start to series and parallel hybrid solutions is presented and respective component modelling approaches are introduced. Finally, the fuel consumption on a given cycle in function of eco-driving parameters is evaluated. It can be seen that hybrid solutions show minimum fuel consumption of about 3 L/100 km, whereas eco-driving habits do change slightly when applied to hybrid architectures because of new technologies such as braking energy recovery. © The Institution of Engineering and Technology 2015. Source

Daboussy M.,CNRS Research Department of Automotive Engineering | Titica M.,University of Nantes | Boillereaux L.,University of Nantes
Canadian Journal of Chemical Engineering

In this article, a dynamic model describing the growth of the green microalgae Chlamydomonas reinhardtii, under light attenuation and sulphur-deprived conditions leading to hydrogen production in a photobioreactor is presented. The strong interactions between biological and physical phenomena require complex mathematical expressions with an important number of parameters. This article presents a global identification procedure in three steps using data from batch experiments. First, it includes the application of a sensitivity function analysis, which allows one to determine the parameters having the greatest influence on model outputs. Secondly, the most influential parameters were identified by using the classical least-squares cost function. This stage is applied to the experimental data collected from a lab-scale batch photobioreactor. Finally, the implementation of an Extended Kalman Filter estimating the biomass concentration, extracellular and intracellular sulphur concentrations is presented. Thereby, the observer uses on-line measurements provided by a mass spectrometer measuring the outlet gas composition (O2, CO2). Software sensor performances and limits are illustrated in simulation and with experimental data. © 2014 Canadian Society for Chemical Engineering. Source

Asserin O.,CEA Saclay Nuclear Research Center | Loredo A.,CNRS Research Department of Automotive Engineering | Petelet M.,CEA Saclay Nuclear Research Center | Petelet M.,CNRS Research Department of Automotive Engineering | Iooss B.,Electricite de France
Finite Elements in Analysis and Design

In this paper, the sensitivity analysis methodology is applied to numerical welding simulation in order to rank the importance of input variables on the outputs of the code like distorsions or residual stresses. The numerical welding simulation uses the finite element method, with a thermal computation followed by a mechanical one. Classically, a local sensitivity analysis is performed, hence the validity of the results is limited to the neighbourhood of a nominal point, and cross effects cannot be detected. This study implements a global sensitivity analysis which allows to screen the whole material space of the steel family mechanical properties. A set of inputs of the mechanical model - material properties that are temperature-dependent - is generated with the help of latin hypercube sampling. The same welding simulation is performed with each sampling element as input data. Then, output statistical processing allows us to classify the relative input influences by means of different sensitivity indices estimates. Two different welding configurations are studied. Considering their major differences, they give a different ranking of inputs, but both of them show that only a few parameters are responsible for the variability of the outputs. To illustrate the pertinence of the overall process, for the first of the two configurations, two series of computations are performed: one for a complete sample and one for its reduced version - where all the secondary parameters are set to mean values. They match perfectly, showing a substantial economy can be done by giving mean values to the rest of the inputs. Sensitivity analysis has then provided answers to what we consider one of the probable frequently asked questions regarding welding simulation: for a given welding configuration, which properties must be measured with a good accuracy and which ones can be simply extrapolated or taken from a similar material? That leads us to propose a comprehensive methodology for welding simulations including four sequential steps: a problem characterization, a sensitivity analysis, an experimental campaign, simulations. © 2011 Elsevier B.V. Source

Dupont T.,CNRS Research Department of Automotive Engineering | Leclaire P.,CNRS Research Department of Automotive Engineering | Panneton R.,Universite de Sherbrooke
Journal of the Acoustical Society of America

The acoustic properties of porous materials containing dead-end (DE) pores have been proposed by Dupont [J. Appl. Phys. 110, 094903 (2011)]. In the theoretical description, two physical parameters were defined (the dead-end porosity and the average length of the dead-end pores). With the knowledge of the open porosity (measured with non-acoustic methods), and the measurement of kinematic porosity (also called the Biot porosity in this article), it is possible to deduce the dead-end porosity. Two acoustic methods for measuring the Biot porosity for a wide range of porosities are proposed. These methods are based on acoustic transmission and on the low and high frequency behaviors of acoustic indicators. The low frequency method is valid for high porosities. It involves measurements in a transmission tube and the knowledge of the theoretical asymptotic behavior of the phase velocity at high frequencies. The high frequency method is based on ultrasonic measurements and on the high frequency asymptotic behavior of the transmission coefficient. It is well adapted for material with relatively low values of porosity. Good precision was found for both methods and materials containing dead end porosity were tested. © 2013 Acoustical Society of America. Source

Gong X.J.,CNRS Research Department of Automotive Engineering | Hurez A.,IUT | Verchery G.,CNRS Research Department of Automotive Engineering
Polymer Testing

This work covers the problems encountered in correctly determining mode I interlaminar fracture toughness of composite materials. Pure mode I tests were performed on double cantilever beam (DCB) specimens composed by quasi-homogeneous and uncoupled multidirectional (MD) laminates using 16 or 26-ply: [α/-α2/α/-α/α2/- α]sym or anti-sym and [0/α/-α/02/- α/0/α/02/α/-α/0]sym, with α = 0°,15°,30°,45°,90°. A finite element analysis shows that the non-uniformity ratio β=(GImax-GIav.)/G Iav% depends not only on the parameter Dc = D 12 2/(D11D22), but also on the specimen geometrical ratios a/b and a/h. The condition of Dc<0.25 is not sufficient to assure a uniform GI width-wise distribution. If we want to study the crack growth between any ply angles, it is difficult to find lay-ups having β<10%. In fact, the crack initiation in MD DCB specimens usually occurred at the middle of the specimens, where GI attained a maximum. Hence, the critical energy release rate GIC has to be measured by the maximum instead of the mean of GI. © 2010 Elsevier B.V. All rights reserved. Source

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