Portail HAL de l'Université du Littoral Côte d'Opale
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MuSeM: Jeu de données multi-capteur avec caméra multispectrale instantanée pour la robotique mobile
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Imbalance Term in the TKE Budget over Waves
No full textInternational audienceIn an attempt to reconciliate air-sea momentum flux estimates derived from open sea observations, from large eddy simulation output fields, and from wind-wave tank measurements, a series of dedicated experiments were conducted in the wind-wave tank of the Large Air-Sea Facility of Marseille, France. The turbulent friction velocity, upon which the momentum flux depends, was estimated from wind measurements by applying four classical methods including the eddy-covariance method and the inertial-dissipation method. The collected data were used to investigate some characteristics of the waveinfluenced boundary layer that were predicted by previous simulations, and to quantify a wave-dependent term of the turbulent kinetic energy equation, the so-called imbalance term ϕ imb . Our results show that the turbulent stress decreases toward lower heights where the effect of waves is large, as in the simulations, and that ϕ imb is in the range 0.3 to 0.7, which is comparable to the value found with open sea data (0.4). These preliminary results have to be confirmed with wave-following probes, because the estimated eddy-covariance flux slightly varied with height, thus it could not be strictly considered to be equal to a constant total flux
« Agir autrement » Guide pour co-construire des trajectoires d’adaptation des territoires littoraux, Rapport Projet Trajectoires Fondations de France
No full textCe guide a été réalisé dans le cadre du projet de recherche action TRAJECTOIRES (Temps long et progressivité de l'action publique. Acceptabilité et opérationnalisation des trajectoires d'adaptation des territoires littoraux) financé par la Fondation de France. Ce projet était à la fois pluridisciplinaire (Economie, Géographie, Psychologie environnementale, Science politique, Droit) et de type « recherche action » mené en partenariat étroit avec des partenaires diversifiés (AURCACe document résulte d’une co-construction rassemblant des chercheurs de diverses disciplines, ainsi que des acteurs divers de collectivités territoriales, services déconcentrés de l’Etat, associations. Il s’agit d’offrir un éclairage opérationnel qui rende compte à la fois des connaissances scientifiques et des résultats observés sur divers terrains. La collaboration étroite avec le CNFPT vise à faciliter l’acquisition de nouvelles compétences et plus généralement l’évolution de l’ingénierie territoriale face aux nouveaux enjeux de la gestion des risques côtiers et de la transition des territoires littoraux.</div
Impact of the EECO on mammalian faunas: New Ypresian localities from Montpellier (France), a multidisciplinary approach
No full textInternational audienceAn integrative chronological study on a new terrestrial sedimentary sequence north of Montpellier (southern France) yields an age ranging from 52.1 to 49.7 Ma. This sequence contains three new mammalian fossil localities, for the first time described in this study, and is associated with the nearby specifically rich site of Mas de Gimel (MP10 -European Mammalian Paleogene Reference Scale [MP]). This study constrains the age of the Grauvian ELMA [European Land Mammal Age] with respect to the geological time scale, suggesting that it is more contemporary with the EECO (Early Eocene Climatic Optimum) than previously considered, and in particular with the period of High Amplitude Climate Fluctuations. These new faunas and data allow us to discuss the relevance of the European Mammalian Paleogene Reference Scale [MP] and to propose new continental biozones for the late Ypresian. It also demonstrates that the late Neustrian fauna (MP8 + 9) is contemporary with the onset of the EECO and that there may be several late-and post-EECO faunas in southern France. Our study moreover suggests phases of diversification during the warm periods, and extinction during the cooling, as observed in North America. Future refined dating of the European fossil localities of this key period will help to discuss the impact of global warming on mammalian communities in the frame of further intercontinental comparisons.Une étude chronologique intégrative d'une nouvelle séquence sédimentaire terrestre au nord de Montpellier (sud de la France) fournit un âge compris entre 52,1 et 49,7 Ma. Cette séquence contient trois nouveaux gisements fossilifères de mammifères, décrits pour la première fois dans cette étude, et est associée au site particulièrement riche du Mas de Gimel (MP10 — Échelle de référence du Paléogène des mammifères européens [MP]). Cette étude contraint l'âge de l'ELMA [Âge des mammifères terrestres européens] du Grauvien par rapport à l'échelle des temps géologiques, suggérant qu'il est plus contemporain de l'EECO (Optimum climatique de l'Éocène inférieur) que ce qui était envisagé précédemment, et en particulier de la période des fluctuations climatiques de haute amplitude. Ces nouvelles faunes et données nous permettent de discuter de la pertinence de l'Échelle de référence du Paléogène des mammifères européens [MP] et de proposer de nouvelles biozones continentales pour l'Yprésien supérieur. Elle démontre également que la faune neustrienne tardive (MP8 + 9) est contemporaine du début de l'EECO et qu'il pourrait exister plusieurs faunes tardives et post-EECO dans le sud de la France. Notre étude suggère par ailleurs des phases de diversification pendant les périodes chaudes et d'extinction pendant le refroidissement, comme observé en Amérique du Nord. Une datation plus précise des sites fossilifères européens de cette période clé permettra d'analyser l'impact du réchauffement climatique sur les communautés de mammifères dans le cadre de comparaisons intercontinentales ultérieures
Limit theorems for squared increment sums of the maximum of two isotropic fractional Brownian fields over a fixed-domain
No full textThe pointwise maximum of two independent and identically distributed isotropic fractional Brownian fields (with Hurst parameter H < 1/2) is observed in a family of points in the unit square C = (-1/2, 1/2] 2 . We assume that these points come from the realization of a homogeneous Poisson point process with intensity N . We consider normalized increments (resp. pairs of increments) along the edges of the Delaunay triangulation generated by the Poisson point process (resp. pairs of edges within triangles). We investigate the asymptotic behaviors of the squared increment sums as N → ∞. We show that the normalizations differ from the case of a unique isotropic fractional Brownian field as obtained in [3] and that the sums converge to the local time of the difference of the two isotropic fractional Brownian fields up to constant factors.</div
Combined supramolecular solvent preparation and solid extraction
No full textInternational audienceClassical extraction involves several time-consuming and costly steps using toxic solvents. Here, we combined the preparation of a cyclodextrin-based supramolecular deep eutectic solvent and the extraction of spent coffee grounds by microwave irradiation in a single step. We tested two new solvents, randomly methylated-β-cyclodextrin:propylene glycol and hydroxypropyl-β-cyclodextrin:ethylene glycol, and compared the results with two classical solvents, chloride:urea (1:2) and ethanol/water 80/20 vol%. We also used classical Soxhlet extraction. We calculated the sustainability of the process using ComplexGAPI. Results show that the optimal one-step extraction conditions were 15 min of irradiation at 80 °C with the addition of 10 wt% water. Under these conditions, the two new solvents showed higher extraction yields of antioxidants and polyphenols than choline chloride:urea (1:2) or ethanol/water 80/20 vol%. Similarly, the half maximal effective concentration and gallic acid equivalent of the Soxhlet extracts were 5 and 3 times lower, respectively, than those obtained with hydroxypropyl-β-cyclodextrin:ethylene glycol (1:40) 10 wt% water. The composition of the extracts from the one-step process was similar to that of the Soxhlet extract. Sustainability analysis revealed low energy consumption, reduced unitary operations and less waste production
A new parallel cooperative landscape smoothing algorithm and its applications on TSP and UBQP
No full textInternational audienceCombinatorial optimization problem (COP) is difficult to solve because of the massive number of local optimal solutions in his solution space. Various methods have been put forward to smooth the solution space of COPs, including homotopic convex (HC) transformation for the traveling salesman problem (TSP). This paper extends the HC transformation approach to unconstrained binary quadratic programming (UBQP) by proposing a method to construct a unimodal toy UBQP of any size. We theoretically prove the unimodality of the constructed toy UBQP. After that, we apply this unimodal toy UBQP to smooth the original UBQP by using the HC transformation framework and empirically verify the smoothing effects. Subsequently, we introduce an iterative algorithmic framework incorporating HC transformation, referred as landscape smoothing iterated local search (LSILS). Our experimental analyses, conducted on various UBQP instances show the effectiveness of LSILS. Furthermore, this paper proposes a parallel cooperative variant of LSILS, denoted as PC-LSILS and apply it to both the UBQP and the TSP. Our experimental findings highlight that PC-LSILS improves the smoothing performance of the HC transformation, and further improves the overall performance of the algorithm