Éditeur(s) : HAL CCSD Institute for Scientific Computing and Information
Résumé : International audience
In this paper, we solve a problem describing the mechanical deformations of a porous medium in the presence of a monophasic linear flow or a two phase nonlinear flow with the purpose of modelizing subsidence of hydrocarbon reservoirs. An essential characteristics of this problem is that the mechanical deformation and the flow have different time scales. In petroleum industry, one uses different very efficient simulators for the flow problem and the mechanical deformations, which enables to handle complex models. Therefore it is necessary to be able to combine as efficiently as possible the exploitation of these simulators. We propose two alternative splitting approaches. The first one is the staggered algorithm used by engineers, which amounts to a Gauss-Seidel method in the one phase linear case. The second approach is based upon the preconditioned conjugate gradient method. We use a numerical multi-scale method in both of these algorithms. We compare these two approaches and we show that the preconditioned conjugate gradient algorithm is faster and more robust than the staggered algorithm. Applying the preconditioned conjugate gradient algorithm therefore seems to compensate for the fact that the inf-sup condition for the mixed discretization method is not satisfied when combining the simulators for the mechanical deformations and for the flow computations.
ISSN: 1705-5105

Droits : http://creativecommons.org/licenses/by/
hal-01449039
https://hal.archives-ouvertes.fr/hal-01449039
https://hal.archives-ouvertes.fr/hal-01449039/document
https://hal.archives-ouvertes.fr/hal-01449039/file/DHLE.pdf

Éditeur(s) : HAL CCSD
Résumé : Session "Articles"
National audience
Nous présentons ici une méthode permettant de créer et de représenter sous forme vectorielle des classes de transition à partir d'une classification supervisée basée sur des arbres de décision flous. Cette méthode est particulièrement utile pour la classification stricte de données dont les frontières sont naturellement diffuses ainsi que pour leur représentation au sein d'un System d'Information Géographique. C'est le cas par exemple des formations forestières entre lesquels les transitions sont généralement étalées sur plusieurs centaines de mètres avec des gradients dépendant de condition environnementales locales ne permettant pas de définir une transition identique dans toutes les directions. La méthode présentée permet d'ajouter des classes lorsque les zones de transition sont trop étendues plutôt que de fixer une frontière arbitrairement
Actes de la conférence RFIA 2012
Lyon, France

Droits : info:eu-repo/semantics/OpenAccess
hal-00656502
https://hal.archives-ouvertes.fr/hal-00656502
https://hal.archives-ouvertes.fr/hal-00656502/document
https://hal.archives-ouvertes.fr/hal-00656502/file/rfia2012_submission_57.pdf

Éditeur(s) : HAL CCSD
Résumé : International audience
Geographic Information Systems (GIS) help addressing geographical and environmental issues by providing information about a region or a city as a set of maps (layers), each one displaying information about a given theme like roads, vegetation, tourist spots or museums for instance. By combining different layers on a region, one can associate a given area to characteristics from their related themes. Indeed, the information from two or more layers might be merged and then transformed into a new layer as defined in map "algebra". When a theme vocabulary is organized as a taxonomy with concepts linked by is-a relationships, there are different ways to annotate an area with a concept depending on the level selected into the layer taxonomy. In this paper, we present an heuristic- based approach for an optimal merging of such layers in a GIS. Our goal is to generate new layers which sum up information from several themes in a most useful way. Two optimization criteria are considered, the average size of resulting areas and the average informative value of their resulting annotation. We demonstrate the validity of the proposed solution, firstly, on a formal example, and then, on a real world application.
Proceedings of the 4th International Conference on Advanced Geographic Information Systems, Applications, and Services
Valencia, Spain

hal-00679555
https://hal.archives-ouvertes.fr/hal-00679555

Éditeur(s) : HAL CCSD
Résumé : National audience
EIAH Proceedings

hal-00634758
https://hal.archives-ouvertes.fr/hal-00634758

Éditeur(s) : HAL CCSD
Résumé : International audience
This paper deals with hybrid optimization take different methods to solve a complex problem. As if the choice of concerning methods is important, the way to combine them is determinant for an ef cient search. The article deals with cooperation strategy between the different layers of an hybrid optimization algorithm. We describ the way it is articulated for an Satellite Constellation Optimization problem. This cooperation allows a dynamical adaptation of the optimization algorithm parameters according to the mutual advance of each search
Journal Européen des Systèmes Avancés

hal-00602267
https://hal.archives-ouvertes.fr/hal-00602267

Éditeur(s) : HAL CCSD
Séminaire du Laboratoire de Mathématiques Informatique et Applications (LAMIA)
Pointe-à-Pitre, Guadeloupe

hal-00835738
https://hal.archives-ouvertes.fr/hal-00835738

Éditeur(s) : HAL CCSD American Geophysical Union (AGU)
Résumé : International audience
The nucleation, propagation, and associated folding of ramp-flat-ramp normal faults were analyzed from field examples developed in a brittle/ductile multilayer sequence of the Huércal-Overa Basin (SE Spain). Gently dipping sandy silt layers, which display a low cohesive strength (C0 = 7 kPa, μ = 34°), favor the development of extensional detachments. A tectonic origin instead of a possible gravitational origin is supported by the perpendicularity between the paleoslope direction of the fluvial-deltaic environment inferred from imbricated pebbles, and the senses of movement deduced from fault slicken-lines. The link between high-angle normal faults (HANFs) --formed at different levels in the layered sequence-- with horizontal fault segments comes to develop ramp-flat-ramp normal faults with associated roll-over in the hanging wall. Observed extensional duplexes are formed by parallel detachments connected through synthetic Riedel faults. These Riedel faults would produce the back-rotation of the individual blocks (horses), i.e., extensional folding of the originally subhorizontal layers. There is no correlation between the analyzed ramp-flat-ramp normal faults, accommodating south-southeastward extension during Serravallian-lower Tortonian, and either the regional Alpujarride/Nevado-Filabride west-directed extensional shear zone or the top-to-the-north detachments within Alpujarride units, which are clearly sealed by Serravallian-lower Tortonian sediments. Therefore, the studied normal faults are restricted to the brittle/ductile multilayer fluvio/deltaic sequence and accommodate moderate late extension instead of belonging to a large crustal extensional system connected with a regional detachment at depth. Therefore, the basin formed in a moderate crustal thickness context where small and medium-scale extensional systems were subordinate structures. These natural examples support the development of low-angle normal faults at very shallow crustal levels in multilayer sequences with suitable rheological conditions.
ISSN: 0278-7407

hal-00750352
https://hal.archives-ouvertes.fr/hal-00750352
DOI : 10.1029/2012TC003130

Éditeur(s) : HAL CCSD
Résumé : We present high-resolution bulk sedimentary δ 15N data from the southern edge of the present-day oxygen minimum zone of the eastern South Pacific. The record is interpreted as representing changes in water column nitrogen removal during the last 70,000 years. We found significant fluctuations in the isotopic signal that suggest major reorganizations of the oxygen minimum zone at millennial timescales. These fluctuations were not related to other millennial-scale changes like the Northern Hemisphere's Dansgaard-Oeschger climate swings or local changes in primary productivity, so appear to be dictated by the Southern Hemisphere's climate rhythm. This is preliminarily corroborated by an overall agreement between our δ 15N data and the sedimentary proxy of ice sheet dynamics in Patagonia, which is in turn correlated with surface water properties at the midlatitude subduction region of the eastern South Pacific intermediate waters. Finally, potential implications on late Quaternary changes in atmospheric CO2 concentrations are discussed.
Paleoceanography / PALEOECEANOGRAPHY

hal-00407260
https://hal.archives-ouvertes.fr/hal-00407260
DOI : 10.1029/2006PA001308

Éditeur(s) : HAL CCSD
Résumé : International audience
Modelling techniques for river hydrologic forecasting systems have taken advantage of machine learning methods especially for flood prediction. But current solutions, mostly based on artificial neural networks do not always meet end users requirements on the readability and the understandability of predictive models. In this paper, we present a new version of our original solution based on the concept of aggregate variables in order to predict flash flood events from observed water level and/or rain measurements, particularly in the context of caribbean watersheds in which flash flood are much uncertain. We combine aggregate variables in juries. Juries of aggregate variables are trained and tested using a typical 10-fold cross validation scheme. Best juries are searched through an evolutionary approach that is optimized. Different parameters are set up like aggregation periods and jury sizes to prove the efficiency of the proposed approach compared to classical solutions.
Congress on Evolutionary Computation (CEC) 2013
Cancun, Mexico

hal-00847582
https://hal.archives-ouvertes.fr/hal-00847582
DOI : 10.1109/CEC.2013.6557656

Éditeur(s) : HAL CCSD
Résumé : National audience
Designing systems able to interact with students in a natural manner is a complex and far from solved problem. A key aspect of natural interaction is the ability to understand and appropriately respond to human emotions. This paper details our response to the continuous Audio/Visual Emotion Challenge (AVEC'12) whose goal is to predict four affective signals describing human emotions. The proposed method uses Fourier spectra to extract multi-scale dynamic descriptions of signals characterizing face appearance, head movements and voice. We perform a kernel regression with very few representative samples selected via a supervised weighted-distance-based clustering, that leads to a high generalization power. We also propose a particularly fast regressor-level fusion framework to merge systems based on different modalities. Experiments have proven the efficiency of each key point of the proposed method and our results on challenge data were the highest among 10 international research teams.
IHM'14, 26e conférence francophone sur l'Interaction Homme-Machine
Lille, France

hal-01089628
https://hal.archives-ouvertes.fr/hal-01089628
https://hal.archives-ouvertes.fr/hal-01089628/document
https://hal.archives-ouvertes.fr/hal-01089628/file/p44-nicole.pdf

Éditeur(s) : HAL CCSD
Résumé : Session "Atelier IHMA"
National audience
Nous présentons une méthode pour la simulation des capacités d'évaluation de la dissemblance de stratégies de construction de dessins. Cette méthode exploite un descripteur structurel des procédures, l'OPSRL, ainsi qu'une mesure de dissemblance que nous présentons. La polyvalence des types de traitements qui peuvent être mis en oeuvre grâce à cette méthode est illustrée sur des jeux de tracés de formes géométriques qui ont été acquis en ligne au moyen de tablettes à digitaliser.
Actes de la conférence RFIA 2012
Lyon, France

Droits : info:eu-repo/semantics/OpenAccess
hal-00660983
https://hal.archives-ouvertes.fr/hal-00660983
https://hal.archives-ouvertes.fr/hal-00660983/document
https://hal.archives-ouvertes.fr/hal-00660983/file/IHMA_06_-_Ney_-_Remi.pdf

Éditeur(s) : HAL CCSD EDP Sciences
https://hal.archives-ouvertes.fr/hal-00521898

hal-00521898
https://hal.archives-ouvertes.fr/hal-00521898

Éditeur(s) : HAL CCSD Wiley
Résumé : Revue de rang A
International audience
This paper studies how to detect anomalies in a distributed manner by using wireless sensor networks (WSNs). We focus on a medical context, where the existing works generally provide large environments to monitor patients using sensors as simple transducers. Those devices forward sensed health parameters to a main base station. This station collects received data and may perform some computations. In this paper, we perform some distributed tasks on the sensors. We propose a distributed algorithm, which allows to raise alarms under some initial rules to alert efficiently medical staff in case of critical situations without needless warnings. Each mote monitors a parameter. When this parameter reaches an abnormal value, the mote communicates with other motes in order to check if it is a ‘local' anomaly or if the patient is in an abnormal situation. In such cases an alarm is raised. We implemented our algorithm over a network of micaZ sensors running under TinyOS. The obtained results show promising perspectives.
ISSN: 1532-0626

hal-00519594
https://hal.archives-ouvertes.fr/hal-00519594
DOI : 10.1002/cpe.1583

Éditeur(s) : HAL CCSD
Résumé : National audience
Séminaire du Laboratoire de Mathématiques Informatique et Applications (LAMIA)
Pointe-à-Pitre, Guadeloupe

hal-00694143
https://hal.archives-ouvertes.fr/hal-00694143

Éditeur(s) : HAL CCSD Dunod
Résumé : International audience
DUT-Technique de commercialisation-2ème année

hal-01312582
https://hal.archives-ouvertes.fr/hal-01312582

Éditeur(s) : HAL CCSD Yokohama
Résumé : International audience
We make use of the viscosity technique to develop a convergent method for approximating a common element of the set of fixed points of a demicontractive operator and the set of solutions of a monotone equilibrium problem. The proposed algorithm is obtained by coupling a modified hybrid steepest descent method with the extragradient algorithm. Under mild conditions, the strong convergence of the sequences generated by the algorithm is obtained. Using this result we obtain two corollaries which improve or develop several corresponding results in this field.
Journal of Nonlinear and Convex Analysis

hal-00779988
https://hal.univ-antilles.fr/hal-00779988

Éditeur(s) : HAL CCSD
Résumé : International audience
ICECS Proceedings
Dubai, United Arab Emirates

hal-00509490
https://hal.archives-ouvertes.fr/hal-00509490

Éditeur(s) : HAL CCSD
Résumé : International audience
We present a study on the optimasation of the number of messages for medical diagnosis over wireless sensors networks (WSNs). We suggest distributed algorithms to diagnosis some diseases while monitoring a patient. Then, we compare the number of messages needed to make a decision between the algorithms. In our approach, each sensor will make some computations in order to participate to the decision. Indeed, some computation and collaboration tasks are performed over the sensors and the final diagnosis is performed in a distributed way. During the experimentation of our algorithms, we used a real data flow extracted from hospital monitoring.
Proceedings of the 14th IEEE Symposium on Computers and Communications (ISCC 2009), July 5-8, Sousse, Tunisia
Sousse, Tunisia

hal-00519593
https://hal.archives-ouvertes.fr/hal-00519593

Éditeur(s) : HAL CCSD
Résumé : International audience
In this paper, via the algebra of generalized functions, we investigate the generalized Riemann's problem associated to conservation laws with analytical coefficients. This allows us to transform the problem into a system of ordinary differential equations. In some particular cases, such that Burgers' and conservative Richard's equation, approximated solutions are obtained by the truncation of the so called Hugoniot-Maslov's chain and numerical simulations are also presented in the case of equations with polynomial coefficients.
Novi Sad Journal of Mathematics

hal-00771405
https://hal.archives-ouvertes.fr/hal-00771405

Éditeur(s) : HAL CCSD
Résumé : International audience
J. Convex Anal.

hal-00695362
https://hal.archives-ouvertes.fr/hal-00695362