Time filter

Source Type

Dunkerque, France

Hequette A.,University of Lille Nord de France | Hequette A.,Laboratoire Doceanologie Et Of Geosciences Log | Hequette A.,CNRS Laboratory of Oceanology and Geosciences | Aernouts D.,ULCO
Continental Shelf Research | Year: 2010

Analyses of shoreline and bathymetry change near Calais, northern coast of France, showed that shoreline evolution during the 20th century was strongly related with shoreface and nearshore bathymetry variations. Coastal erosion generally corresponds to areas of nearshore seabed lowering while shoreline progradation is essentially associated with areas of seafloor aggradation, notably east of Calais where an extensive sand flat experienced seaward shoreline displacement up to more than 300m between 1949 and 2000. Mapping of bathymetry changes since 1911 revealed that significant variation in nearshore morphology was caused by the onshore and alongshore migration of a prominent tidal sand bank that eventually welded to the shore. Comparison of bathymetry data showed that the volume of the bank increased by about 10×107m3 during the 20th century, indicating that the bank was acting as a sediment sink for some of the sand transiting alongshore in the coastal zone. Several lines of evidence show that the bank also represented a major sediment source for the prograding tidal flat, supplying significant amounts of sand to the accreting upper beach. Simulation of wave propagation using the SWAN wave model (Booij et al., 1999) suggests that the onshore movement of the sand bank resulted in a decrease of wave energy in the nearshore zone, leading to more dissipative conditions. Such conditions would have increased nearshore sediment supply, favoring aeolian dune development on the upper beach and shoreline progradation. Our results suggest that the onshore migration of nearshore sand banks may represent one of the most important, and possibly the primary mechanism responsible for supplying marine sand to beaches and coastal dunes in this macrotidal coastal environment. © 2010 Elsevier Ltd.

Drira R.,RIADI Laboratory | Laroussi M.,RIADI Laboratory | Le Pallec X.,LIFL Laboratory | Warin B.,ULCO
IEEE Transactions on Learning Technologies | Year: 2012

In this paper, we first demonstrate that an instructional design process of Technology Enhanced Learning (TEL) systems based on a Model Driven Approach (MDA) addresses the limits of Learning Technology Standards (LTS), such as SCORM and IMS-LD. Although these standards ensure the interoperability of TEL systems across different Learning Management Systems (LMS), they are generic and lack expressiveness. In addition, the use of LTS limits designers to using a compliant LMS. MDA addresses these limits by allowing pedagogic modeling based on specific modeling languages and by ensuring interoperability across Learning Management Systems based on model transformations. In the context of an MDA-based design process, we propose a novel approach, named ACoMoD, to help designers to bridge the gap between pedagogic modeling and LMS specifications, based on graphic and interactive model transformations. Our approach, implemented with a tool called Gen-COM, enables designers to choose more effective LMS tools, based on a contextual recommendation of best practice for LMS tool use. Gen-COM and its evaluation with designers are described in this paper. The main results show, first, the usefulness of tailoring pedagogy with LMS tools based on the proposed solution. Second, the results show different levels of usefulness of the proposed assistance according to different situations that will be detailed. Some improvements are suggested and are in progress concerning the extension of Gen-COM to offer assistance to designers based on their profiles. © 2008-2011 IEEE.

Quesnel G.,French National Institute for Agricultural Research | Trepos R.,French National Institute for Agricultural Research | Ramat E.,ULCO
SIMULTECH 2012 - Proceedings of the 2nd International Conference on Simulation and Modeling Methodologies, Technologies and Applications | Year: 2012

The observation of a simulation is an important task of the modeling and simulation activity. However, this task is rarely explained in the underlying formalism or simulator. Observation consists to capture the state of the model during the simulation. Observation helps understand the behavior of the studied model and allows improving, analyzing or debugging it. In this paper, we focus on appending an observation mechanism in the Parallel Discrete Event System Specification (PDEVS) formalism with guarantee of the reproducible simulation with or without observation mechanism. This extension to PDEVS allows us to observe models at the end of the simulation or according to a time step. Thus, we define a formal specification of this extension and its abstract simulators algorithms. Finally, we present an implementation in the DEVS framework VLE.

Cherel Y.,CNRS Chize Center for Biological Studies | Koubbi P.,University Pierre and Marie Curie | Giraldo C.,University Pierre and Marie Curie | Penot F.,University Pierre and Marie Curie | And 6 more authors.
Polar Science | Year: 2011

We used the stable isotope method to investigate the ecological niches of Antarctic fishes, with δ13C and δ15N as proxies of fish habitats and dietary habits, respectively. Muscle isotopic signature was measured for each of 237 delipidated tissue samples from 27 fish species collected offshore Adélie Land, East Antarctica. Overall, δ13C values ranged from -25.3‰ to -18.2‰, thus allowing characterizing of the fish habitats, with inshore/benthic species having more positive δ13C signatures than offshore/pelagic ones. No clear difference in the δ13C values of pelagic fishes was found between species living in neritic and oceanic waters. Overall, the δ15N signatures of neritic pelagic and epibenthic fishes encompassed ∼1.0 trophic level (3.1‰), a higher difference than that (1.4‰) found within the oceanic assemblage. Fishes with the lowest and highest δ15N values are primarily invertebrate- and fish-eaters, respectively. The isotopic niches of fishes illustrate the different mechanisms allowing coexistence, with most fishes segregating at least by one of the two niche axes (δ13C and δ15N). Muscle isotopic values also document interindividual foraging specialization over the long-term in coastal benthic fishes, but not in more offshore pelagic species. Finally, the δ15N signatures of fishes overlap with those of penguins and seals, indicating that seabirds and marine mammals share the upper levels of the Antarctic pelagic ecosystem with some large fish species. In conclusion, the concept of isotopic niche is a powerful tool to investigate various aspects of the ecological niche of Antarctic fishes, thus complementing the use of other conventional and non-conventional approaches. © 2011 Elsevier B.V. and NIPR.

Koubbi P.,CNRS Oceanography Laboratory of Villefranche | Moteki M.,Tokyo University of Marine Science and Technology | Duhamel G.,MNHN | Goarant A.,CNRS Oceanography Laboratory of Villefranche | And 6 more authors.
Deep-Sea Research Part II: Topical Studies in Oceanography | Year: 2011

The Southern Ocean is delimited by major frontal zones which influence pelagic life at the spatial macroscale. There is a sharp ecological segregation of pelagic fish that inhabit this ocean with some families living in the neritic zone and others in the oceanic zone. The neritic zone is dominated by fish of the Notothenioid suborder. In the oceanic zone, mesopelagic species are dominated by myctophids. Their spatial distribution is highly influenced by meso- or sub-mesoscale oceanographic features. Myctophid presence/absence records from historical surveys and from the Census of Antarctic Marine Life were used to model species assemblages in the Indian sector of the Southern Ocean by using generalized dissimilarity modeling. This statistical technique is data-driven and is used in conjunction with Geographic Information Systems for creating models between communities and environmental factors. Application of these models in large unsurveyed areas is possible and helps in delineating regions of potential similar assemblages. This will allow us to move from the bioregionalization of the Southern Ocean based on only abiotic factors and chlorophyll, to its ecoregionalization by adding species assemblages. © 2010.

Discover hidden collaborations