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Lascoup B.,Laboratoire Structure et Materiaux | Perez L.,CNRS Nantes Thermocinetique Lab | Autrique L.,Laboratoire DIngenierie des Systemes Automatises | Criniere A.,IFSTTAR
Composites Part B: Engineering | Year: 2013

Implementation of periodic thermal excitation to identify thermal properties (conductivity, heat capacity, diffusivity) of complex composite materials at different investigation scales (from micrometer to millimetre) presents many advantages. These methods are usually based on the thermal waves phase lag observation compared to a reference signal. In fact, phase lag evolution versus distance to the heating source or versus excitation frequency is quite informative about numerous material characteristics. For example, considering that a structural defect can modify heat propagation inside a material, diagnosis can be performed from phase lag observations and comparisons between samples with and without defects. Numerous studies have been performed considering global heating (a quite large surface of the investigated composite material is heated and defect depth or size can be detected). The proposed approach is original since periodic heating is local and aims to detect defects in the periphery of the excitation. Based on a mathematical model for thermal waves propagations and introducing complex temperature for numerical resolution (finite element method), a feasibility study has allowed a sensitivity analysis. This preliminary study also provides information on the operating protocol, for heating (frequency, power, size of the source), and observation (transmission or reflection). Then, experimental device and early experimental results are briefly exposed. © 2012 Elsevier Ltd. All rights reserved.

Perez L.,CNRS Nantes Thermocinetique Lab | Museux N.,Laboratoire DIngenierie des Systemes Automatises | Autrique L.,Laboratoire DIngenierie des Systemes Automatises | Lormel C.,Laboratoire DIngenierie des Systemes Automatises
Journal Europeen des Systemes Automatises | Year: 2011

In order to determine the risks of invalidating burns and to optimize the protection of individuals subjected to a laser attack, the development of a mathematical model is required. This predictive tool aims to estimate the evolution of temperature in the three cutaneous layers of skin. In such a context, the determination of key parameters governing the heat transfers is essential. A major difficulty lies in the fact that the thermal diffusivities of each layer of the human skin are not accurately known. The required in vivo identification of such parameters provides numerous constraints to avoid tissue trauma. The periodic methods are therefore particularly adapted. Such methods allow to obtain a set of relevant information by providing measurements which only slightly heat the cutaneous layers. © 2011 Lavoisier, Paris.

Kefi M.,Laboratoire DIngenierie des Systemes Automatises | Barichard V.,Laboratoire Detude Et Of Recherche En Informatique Dangers | Richard P.,Laboratoire DIngenierie des Systemes Automatises
JFPC 2013 - Neuviemes Journees Francophones de Programmation par Contraintes | Year: 2013

We propose to use constraint programming (CP) to assist the user in 3D layout of restricted virtual environments (VEs). With this aim in mind, we integrated a constraint solver, into a professional authoring tool allowing the development of 3D real-time applications. The solver is used to formalize and develop different types of layout constraints and to find a solution to a userspecified layout problem. A communication module was developed to transmit the solution to the VE which automatically re-arranges itself. Modeling the problem and finding solutions are completely transparent for the user since he/she interacts with the VE regardless of the resolution mechanisms. In addition to the automatic objects placement, the proposed system can be used to assist the user during a manual layout by providing visual informations about the areas in which a given object cannot be placed. An experimental study has been carried out to investigate the effect of the provided look ahead-based assistance on user performance in 3D layout tasks.

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