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Search Results: 1 - 10 of 208527 matches for " Gildas L'Hostis "
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Thermal Activation of Asymetrical Composites for Vibration Control  [PDF]
Axel Imbert, Gildas LHostis, David Rigel Rigel, Fabrice Laurent, Bernard Durand
Modern Mechanical Engineering (MME) , 2013, DOI: 10.4236/mme.2013.33A001
Abstract:

The CBCM (Controlled Behaviour Composite Material) is a thermal active composite, which has been developed for morphing applications. The thermal activation is made by a source of heating generated within the composite structure. The coupling between the induced thermal field and the thermomechanical properties of the various components of the composite structure leads to the change of the structure shape. The heat source is generated by Joule effect, Carbon yarns inserted in the composite, are connected to a power supply. The application field of CBCM technology is the domain of shape modification and active assembly. The objective of this work is to illustrate the capabilities of CBCM in the domain of vibration control. We will study several reference plates with different constitution. The influences of these different constitutions, of the CBCM effect and the loss of stiffness for the matrix will be highlighted, for two boundary conditions, free/free and embedded/embedded.

Thermaly Active Structures for Shape Morphing Applications
Gildas L'Hostis,Karine Buet-Gautier,Bernard Durand
Smart Materials Research , 2012, DOI: 10.1155/2012/530217
Abstract: For shape morphing application, thermal activation coupling to a bimetallic strip effect can be a substitute for classical actuators, piezoelectrical or shape memory alloys. The controlled behaviour of composite material (CBCM) is a thermaly activated composite material. The thermal activation is made thanks to carbon yarns which are connected to a power supply. If the anisotropy of the structure is well organized, the desired deformation is reached when the temperature within the composite is rising. To obtain a CBCM morphing composite structure, it is necessary to design a specific structure. The aim of this work is to show that it is possible to adapt the CBCM principle in order to transform any kind of classical composite structure to an active structure. The first part of this work consists in presenting the experimental results for two examples of composite beams. The second part is about the active structure FEM modeling and the development of adapted tools for this particular design. 1. Introduction Because of their capacity of actuation, morphing structures are used to simplify mechanisms by reducing the number of moving parts. Three main actuation technologies are commonly used: piezoelectricity, shape memory alloys, or thermal effect. In the case of a structure with bistable effect, these technologies are used to activate the shape changing by piezoactuation [1–3], SMA actuation [4–6], and thermal actuation [7–9]. The field of applications for bistable structures is limited because they have only two positions of stability witch are not adjustable and link to the structure geometry. In the case of standard not bistable composite structures, the main problem is the link between the composite and the actuator. Many works can be found with SMA [10, 11] actuators or piezoactuators like macro-fiber composite (MFC) [12, 13], but the interface strength between the actuator and the composite plays a crucial role in the time life of the structure that is a limit especially when the rigidity of the composite structure is high. To overcome problems of bonding between the actuator and the structure, the bimetallic strip effect coupled to an internal thermal actuation can be a solution. Indeed the whole structure can be considered as an actuator, and the problems of interface decohesion are not concentrated at the interface actuator/structure but distributed all along the interfaces of the laminate composite. Controlled behaviour composite material (CBCM) [14–18] is a thermal actuator developed ten years ago. There are two different ways to use the CBCM
Thermally Activated Composite with Two-Way and Multi-Shape Memory Effects
Abdul Basit,Gildas L'Hostis,Marie José Pac,Bernard Durand
Materials , 2013, DOI: 10.3390/ma6094031
Abstract: The use of shape memory polymer composites is growing rapidly in smart structure applications. In this work, an active asymmetric composite called “controlled behavior composite material (CBCM)” is used as shape memory polymer composite. The programming and the corresponding initial fixity of the composite structure is obtained during a bending test, by heating CBCM above thermal glass transition temperature of the used Epoxy polymer. The shape memory properties of these composites are investigated by a bending test. Three types of recoveries are conducted,?two classical recovery tests: unconstrained recovery and constrained recovery, and a new test of partial recovery under load. During recovery, high recovery displacement and force are produced that enables the composite to perform strong two-way actuations along with multi-shape memory effect. The recovery force confirms full recovery with two-way actuation even under a high load. This unique property of CBCM is characterized by the recovered mechanical work.
Transports et aménagement du territoire: cartographie par images de synthèse d'une métrique réseau
Alain L'HOSTIS
Mappemonde , 1996,
Abstract: à partir d'une comparaison des vitesses de parcours sur plusieurs modes de transport, on construit une représentation en relief de l'espace-temps. On peut visualiser, sur cette surface complexe en trois dimensions, les distorsions de l'espace provoquées par les réseaux de transport rapides.
Preface
LHostis Valérie,Philipose Ken,Gens Robert,Gallé Christophe
EPJ Web of Conferences , 2011, DOI: 10.1051/epjconf/20111200001
Abstract:
Change-Point Detection for General Nonparametric Regression Models  [PDF]
Murray D. Burke, Gildas Bewa
Open Journal of Statistics (OJS) , 2013, DOI: 10.4236/ojs.2013.34030
Abstract: A number of statistical tests are proposed for the purpose of change-point detection in a general nonparametric regression model under mild conditions. New proofs are given to prove the weak convergence of the underlying processes which assume remove the stringent condition of bounded total variation of the regression function and need only second moments. Since many quantities, such as the regression function, the distribution of the covariates and the distribution of the errors, are unspecified, the results are not distribution-free. A weighted bootstrap approach is proposed to approximate the limiting distributions. Results of a simulation study for this paper show good performance for moderate samples sizes.
Le CECR, un outil pour réformer l’enseignement/ apprentissage du fran ais en milieu universitaire chinois
Gildas Humeau
Synergies Chine , 2012,
Abstract: Le Cadre Européen Commun de Référence pour les Langues (CECR) et l’approche qu’il retient, la perspective actionnelle, peuvent être per us en Chine comme une nouvelle méthodologie à prétention universaliste que l’on souhaiterait imposer de l’extérieur. Cet article vise à montrer qu’au contraire, le Cadre se caractérise par une grande souplesse, ce qui permet de le contextualiser, afin de mettre l’accent dans le Cadre sur ce qui est le plus utile à une réforme de l’enseignement-apprentissage du fran ais en Chine dans une perspective actionnelle. L’article s’attarde sur les termes de tache et de texte, pour montrer par ses exemples comment la terminologie employée dans le Cadre peut contribuer à la réforme de l’enseignement-apprentissage du fran ais en Chine
La mer et l’insistance paradoxale dans quelques poèmes de G. M. Hopkins The Sea and Paradoxical Insistence in some Poems by G. M. Hopkins
Gildas Lemardelé
Revue LISA / LISA e-journal , 2009, DOI: 10.4000/lisa.87
Abstract: The impact of the sea in G. M. Hopkins’s poems cannot be overlooked, if only because of the pivotal role it plays in his most famous poem “The Wreck of the Deutschland”. Other poems however, display maritime or water-related elements that are fraught with significance. In Hopkins’s poetry, the sea is thus essentially and intricately linked to poetical, philosophical or theological tenets. When he resorts to the sea imagery, violence and benevolence are intertwined, but this binary stance is ultimately subsumed in what can be defined as an illustration of divine insistence as a fundamentally paradoxical principle, which in turn informs the poet’s personal spiritual experience.
Multi-level agent-based modeling - A literature survey
Gildas Morvan
Computer Science , 2012,
Abstract: During last decade, multi-level agent-based modeling has received significant and dramatically increasing interest. In this article we present a comprehensive and structured review of literature on the subject. We present the main theoretical contributions and application domains of this concept, with an emphasis on social, flow, biological and biomedical models.
Multivariate Stop loss Mixed Erlang Reinsurance risk: Aggregation, Capital allocation and Default risk
Gildas Ratovomirija
Quantitative Finance , 2015,
Abstract: In this paper, we address the aggregation of dependent stop loss reinsurance risks where the dependence among the ceding insurer(s) risks is governed by the Sarmanov distribution and each individual risk belongs to the class of Erlang mixtures. We investigate the e?ects of the ceding insurer(s) risk dependencies on the reinsurer risk profile by deriving a closed formula for the distribution function of the aggregated stop loss reinsurance risk. Furthermore, diversification e?ects from aggregating reinsurance risks are examined by deriving a closed expression for the risk capital needed for the whole portfolio of the reinsurer and also the allocated risk capital for each business unit under the TVaR capital allocation principle. Moreover, given the risk capital that the reinsurer holds, we express the default probability of the reinsurer analytically. In case the reinsurer is in default, we determine analytical expressions for the amount of the aggregate reinsured unpaid losses and the unpaid losses of each reinsured line of business of the ceding insurer(s). These results are illustrated by numerical examples.
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