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Bestaoui Y.,French National Center for Scientific Research | Kuhlmann H.,CNRS Systems and Applications of Information Technologies and Energy Laboratory
48th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition | Year: 2010

The objective of this paper is to present the preliminary results of a model of a quadrotor airship, taking into account wind effect as well as the varying mass effects, using Newton formulation. Euler angles are used for kinematics. For dynamics, a mathematical description of a dirigible flight must contain the necessary information about aerodynamic, structural and other internal dynamic effects (engine, actuation) that influence the response of the airship to the controls. Copyright © 2010 by Bestaoui.


Moulin J.,University Paris - Sud | Mazaleyrat F.,CNRS Systems and Applications of Information Technologies and Energy Laboratory | Mendez A.,University Paris - Sud | Dufour-Gergam E.,University Paris - Sud
Journal of Magnetism and Magnetic Materials | Year: 2010

Thin films of Finemet-type alloy with thickness varying from 50 to 1000 nm have been deposited by RF sputtering and annealed at temperature ranging from 150 to 450 °C. Their magnetic and structural properties have been characterized using alternating gradient field magnetometry and X-ray diffraction. In addition, the stress in the films has been measured as a function of temperature from the curvature of the wafers using a laser scanning technique. The coercive field of the films first decreases with annealing temperature due to stress relaxation, and then increases again when crystallisation begins. The optimal annealing conditions comprises between the glass transition and the crystallisation temperature. Its is observed that the coercivity of the as-deposited material is continuously decreasing as the thickness increases, following an inverse square root dependence, in relation with the stress-induced magneto-elastic contribution to the total anisotropy. By opposition, it has been found that the coercive field of devitrified and totally relaxed films is inversely proportional to film thickness. In order to explain this evolution, a model is proposed, based on random anisotropy considerations applied to thin films in which the anisotropy was considered localised in the dimension of thickness. © 2009 Elsevier B.V. All rights reserved.


Guo S.-S.,Wuhan University | Francais O.,CNRS Systems and Applications of Information Technologies and Energy Laboratory
Analytical Chemistry | Year: 2011

Electrochemical techniques based on ultramicroelectrodes (UMEs) play a significant role in real-time monitoring of chemical messengers' release from single cells. Conversely, precise monitoring of cells in vitro strongly depends on the adequate construction of cellular physiological microenvironment. In this paper, we developed a multilayer microdevice which integrated high aspect ratio poly(dimethylsiloxane) (PDMS) microfluidic device for long-term automated perfusion culture of cells without shear stress and an independently addressable microelectrodes array (IAMEA) for electrochemical monitoring of the cultured cells in real time. Novel design using high aspect ratio between circular "moat" and ring-shaped micropillar array surrounding cell culture chamber combined with automated "circular-centre" and "bottom-up" perfusion model successfully provided continuous fresh medium and a stable and uniform microenvironment for cells. Two weeks automated culture of human umbilical endothelial cell line (ECV304) and neuronal differentiation of rat pheochromocytoma (PC12) cells have been realized using this device. Furthermore, the quantal release of dopamine from individual PC12 cells during their culture or propagation process was amperometrically monitored in real time. The multifunctional microdevice developed in this paper integrated cellular microenvironment construction and real-time monitoring of cells during their physiological process, and would possibly provide a versatile platform for cell-based biomedical analysis. © 2011 American Chemical Society.


El Korso M.N.,CNRS Systems and Applications of Information Technologies and Energy Laboratory | Renaux A.,University Paris - Sud | Boyer R.,University Paris - Sud | Marcos S.,University Paris - Sud
IEEE Transactions on Signal Processing | Year: 2013

This correspondence investigates lower bounds on estimator's mean square error applied to the passive near field source localization. More precisely, we focus on the so-called threshold prediction for which these bounds are known to be useful. We give closed form expressions of the McAulay-Seidman, the Hammersley-Chapman-Robbins, the McAulay-Hofstetter bounds and also, a recently proposed bound, the so-called Todros-Tabrikian bound, for the deterministic observation model (i.e., parameterized mean) and the stochastic observation model (i.e., parameterized covariance matrix). Finally, numerical simulations are given to assess the efficiency of these lower bounds to approximate the estimator's mean square error and to predict the threshold effect. © 2012 IEEE.


Idoughi L.,University Paris - Sud | Mininger X.,University Paris - Sud | Bouillault F.,University Paris - Sud | Bernard L.,University Paris - Sud | Hoang E.,CNRS Systems and Applications of Information Technologies and Energy Laboratory
IEEE Transactions on Magnetics | Year: 2011

The aim of the method detailed in this paper is to get an equivalent thermal model of a stator slot, in order to simplify the calculation of desired temperatures in an electrical machine winding. This study is divided in two steps: First, the equivalent thermal conductivity is deduced from a homogenization of the winding, and next, a discretization is achieved using the finite integration technique considering transient analysis. In order to evaluate the method, results from the equivalent model are compared with finite element simulations considering two slot geometries. © 2011 IEEE.

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