Vignon M.,UPPA |
Vignon M.,French National Institute for Agricultural Research
Marine Ecology Progress Series | Year: 2015
Otolith shape analysis provides a practical basis for stock separation, useful in fisheries management. A wide range of factors affect otolith morphology and a fundamental challenge in morphometric stock identification is to develop a consensus on the biological interpretation of otolith shape variation. To date, there are few comprehensive reports that have examined various factors simultaneously at multiple scales in natural conditions. In this study, I identified sources of otolith shape variation across spatial and taxonomic scales using a new hierarchical partitioning method embedded in a geometric morphometric framework. Various environmental, taxonomic and endogenic factors which affect otolith shape were quantitatively investigated in 2077 coral reef fishes. Using the new partitioning method, allometry accounted for a considerable degree of otolith shape variation at all scales and contributed more variation to regional differences than did habitats or islands. While large-scale variations are expected to be associated with significant shape variation, the study provides quantitative evidence that both local environmental variables and large-scale patterns contribute equally to total otolith shape variation. Models that aim at discriminating stocks and forecasting stock boundaries implicitly assume that the within-stock morphological variation is negligible in regard to the variation that exists among stocks. The importance of local environmental variables may therefore act as an important confounding effect into those predictive models. More generally, the degree of contribution of some variables differed substantially among the taxonomic scales, as did their relationship among spatial scales. A scaledependent understanding of factors affecting otolith morphology is critical in understanding the integrity of fish populations and is an effective tool in management of fisheries resources. © Inter-Research 2015.
Soulier L.,Institute des Milieux Aquatiques |
Hemery G.,French Natural History Museum |
Mouches C.,UPPA |
Lalanne Y.,UPPA |
And 4 more authors.
Journal of Marine Systems | Year: 2013
To date, the scarcity of year-round and long-term programmes integrating multi-dimensional data has hindered the development of a good understanding of cetacean mortality worldwide. This study uses data from: 1) standardised shipboard surveys (1980-2002), 2) standardised stranding surveys (1980-2002) and 3) landings of fishing fleets (2000-2002) in the Bay of Biscay. It investigates the correlations between stranding, at-sea encounter rate and the fishing index for three common cetaceans: common dolphin (Delphinus delphis), bottlenose dolphin (Tursiops truncatus) and long-finned pilot whale (Globicephala melas).At the monthly scale, a seasonal stranding pattern significantly congruent with the at-sea encounter rate and the fishing index for D. delphis is revealed. At the inter-annual scale, stranding and at-sea encounter rates are shown to be correlated (p=. 0.013-0.044 according to species) and significantly increasing in abundance. Temporal variation in the ratio between individuals seen alive at sea and those stranded shows no significant trend suggesting that stranding is better explained by at-sea abundance than by the fishing index.Managers can use these findings to re-evaluate the relative contribution of by-catch fisheries in the context of observed changes of at-sea cetacean abundance and the link to oceano-climatic changes and other anthropogenic causes. © 2012 Elsevier B.V.
Lalanne Y.,UPPA |
Estuarine, Coastal and Shelf Science | Year: 2015
On the French Basque Coast (southwest of France), the Yellow-legged gull Larus michahellis has undergone a widespread demographic and geographical increase in the last decade, originally by population breeding in northern Iberia. The demographic increase seems to be due to a combination of several factors: the establishment of a landfill close to the coast and the availability of nesting sites.Birds foraging on landfill sites affect day-to-day site operation. In recent years, thousands of gulls were present daily on the landfill site and have used waste as another feeding opportunity. Management methods were used to limit access of birds to the landfill site and to control the population to a natural dynamic. Distress calls and pyrotechnic means were used on the landfill site for 11 months. Abundance, behavior, efficacy of the deterring systems and distribution along the whole coast were studied.Initial results showed a significant decrease in the abundance of gulls on the landfill site. A change in their behavior was also noted with a reduction in resting and feeding birds. This, combined with the uninterrupted, random, deterring system at the landfill site showed an efficient measure to control gulls population. Monitoring along the coast did not show any significant impact on common resting sites.Despite these promising results, we cannot exclude a new opportunistic response from the gulls. In addition, the proximity of Spanish colonies requires cross-border management for effective control of the population. Long-term monitoring is needed both at the landfill site to measure possible habituation and at the nesting sites to assess breeding success after one year of deterring actions. © 2015 Elsevier Ltd.
Al-akhdar S.,French Institute of Petroleum |
Ding D.Y.,French Institute of Petroleum |
Dambrine M.,UPPA |
Society of Petroleum Engineers - North Africa Technical Conference and Exhibition 2012, NATC 2012: Managing Hydrocarbon Resources in a Changing Environment | Year: 2012
Assisted history-matching is now widely used to constrain reservoir models. The objective of history match process is to improve the model in order to reproduce the production history while honoring the structural properties of the geological model. For that purpose, an objective function is defined in order to measure the mismatch between the simulation results and the production history. This objective function is usually minimized using a gradient-based optimization algorithm. However, history-matching of a large number of parameters in hydrocarbon reservoirs is a challenge because of several reasons: scarcity of available measurements relative to the number of unknowns, computational effort required for large reservoir and the need of insure that solutions are geologically realistic. All of these problems can be helped by using algorithms that rely on efficient and parsimonious descriptions (or parameterizations) of reservoir properties. In this work, a history matching methodology is presented. First, a sensitivity study is performed for identifying the most relevant inversion parameters affecting the history-matching. The gradual deformation method is applied for the parameterization. Then, a new optimization technique, based on data partition for the gradient calculations, is studied for regional and well level history matching. The objective function is first split into local components, and the principal parameters are reduced for each component. In this context, we can propose perturbation designs with a smaller number of perturbations for the gradient computation. The proposed new technique is successfully applied on a real case in Libya in an integrated workflow, which makes history-matching with a large number of parameters tractable. Copyright 2012, Society of Petroleum Engineers.
Proceedings of 2012 International Conference on Complex Systems, ICCS 2012 | Year: 2012
The holistic approach of the description of a living system is based on the concept that the system participates not only to its evolution but also to that of all the sub-systems it contains and all the systems of which it is a sub-system (Fig. 1). No system can be defined as an independent, organizationally closed space but rather as an independent, autonomous closed 'time and timer'. Its time modularity is revealed by rhythms at different scales. The clocks of the system result from recalls of both external and internal time information. The watches, clocks and calendars, which are the actors of endogenous rhythms, are built as a result of the memorization of past responses of interaction (phase shift delays, entrainments, breakages) between its endophysiotope and ecoexotope. The system needs to be both a clock-maker, a watch-maker and a wake-maker. So modeling has to take into account 'simultaneously' the concepts of  - temporal window: 'Before the time, that is not the time. After the time, this no longer is the time.', - time latency and time shifting: 'It is necessary to give some time to the time.', - compartmentation of the time: 'There is a time for each event. And each event is located into its time place.', - nonlinearity and non-summation: 'The temporal Whole is both more and less than the sum of its Parts.' and - interactions between time and space: 'The arrow of the time structures the clocks of living systems. But, the living systems structure back the arrow of their time.' . Calendars are tools for forecasting gates (allowed time zones of a cycle through which an event may emerge) and fixing a time horizon (a fixed point in the future at which a processes will be evaluated or be assumed to end or start). The time knowledge needs the design by the living system of a range of skills and tools used to manage time when accomplishing specific tasks to survive. It appears that timelines are designed as ellipses, projected on a plan or a Moebius strip, labeled with dates alongside and events labeled on the points where they would have happened. The emergence of a new blueprint runs through the juxtaposition and embedment of previous systems. The new time Whole is both more and less than the sum of its Parts (Table 1), it merges through the simultaneous metamorphoses of the Parts into the Whole. But each subsystem maintains its space-time identity into the Whole of which it is a partner. The partial autonomy of each partner is allowed through the maintenance of individual or collective, spatial and temporal boundaries. These interfaces structure the spatial and temporal integration of the parts into the endophysiotope (ENDO) of their whole, and of the whole into the ecoexotope (EXO) of its survival. The transition from one level of organization to an adjacent and superior one is the result of the building of a new, spatial and temporal, network. In this new orderly spaced-timed system all braces are allowed and each partner owns a special place, both through the time and into the space. The integration of the parts, and simultaneously of the whole, merges through the building of Associations for the Reciprocal and Mutual Sharing of Advantages and DisAdvantages (http://armsada.eu). This allows, in a no-change ecoexotope (Fig. 6), the maintenance of both the requisite variety of the partners and the unity of the whole . If changes of the endophysiotope or ecoexotope, this is the only way to make a new networking mode of organization and integration. These associations merge through the interactive fitness between the capacity 'to welcome' of the ecoexotope and the capacity 'to be welcomed' of the endophysiotope of each parcener. Failures of medical treatments and pathological processes can be explained in terms of 'irregularities' or breakages of the time architecture. Inside a system, the time can stop, move with different speeds, jump from one step to another, but it will never turn back. When a step is in the past you need to turn forward a complete cycle to reach it again (anthocyanin adaptive synthesis, asthma crises, rhythms of peroxidase capacities, glycaemia regulation, awakenings times, forest equilibrium). (10 figures, 2 tables) © 2012 IEEE.
Gicquel L.,CEA Cadarache Center |
Latge C.,CEA Cadarache Center |
Simon N.,CEA Cadarache Center |
Hobbes Ph.,Rouen Court of Appeal |
And 3 more authors.
International Congress on Advances in Nuclear Power Plants 2010, ICAPP 2010 | Year: 2010
The Supercritical CO2 Brayton Cycle could be a promising option to enhance the competitiveness of future Sodium Fast Reactor due to its high thermodynamic efficiency and turbine compactness. Furthermore, it may suppress the difficulties related to the sodium/water reaction. Nevertheless, it is highly necessary to get thermodynamic and kinetics information on the potential sodium/CO2 chemical interaction and its potential consequences, to compare both of the systems. Kinetics chemical interactions were investigated via calorimetric techniques as Accelerating Rate Calorimetry which gave preliminary information on the reaction orders and via the theoretical and experimental study of a biphasic reactive jet of CO2 into sodium. A theoretical model was built to describe jets of CO2 into sodium to simulate a leak in a tube heat exchanger between the sodium coolant and the energy conversion fluid. Kinetics parameters are introduced in the model and have to be identified comparing theoretical and experimental data as temperature distribution within a jet of CO2 into sodium. An experimental bench was designed and built in CEA to enable the realization of reactive gas jets in liquid sodium and to allow by identification, the determination of kinetics parameters for Na-CO2 reaction.
Jaafar O.,Geosciences Montpellier |
Pezard P.A.,French National Center for Scientific Research |
Perroud H.,UPPA |
Denchik N.,Geosciences Montpellier |
And 3 more authors.
Near Surface Geoscience 2014 - 20th European Meeting of Environmental and Engineering Geophysics | Year: 2014
The Maguelone experimental site has been the subject of surface and downhole geophysical monitoring of gas injection experiments in a shallow subsurface clastic reservoir. In particular, time-lapse sonic logs were recorded through PVC liners in two holes located within meters of the gas injection hole, before, during and after a series of gas injections. The sonic data, once compared to other logs and core petrophysical measurements have been processed to eliminate the liner and joints contributions, then analysed in terms of Vp velocities and amplitudes before, during and after injection. While Vp velocity changes appear limited in the porous unconsolidated coastal and clastic sediments, a stronger signal is obtained in terms of amplitude reduction with an increase in gas saturation in front of the sandy and gravel-rich layers. In all, time-lapse sonic logging through PVC provides a means to detect and monitor gas injection and storage in geological reservoirs, leading to a view on subsurface dynamics over time.
Grisel Y.,UPPA |
Fourbil J.,ONERA |
Inverse Problems in Science and Engineering | Year: 2015
We are interested in the localization of defects in non-homogeneous non-absorbing media, with far-field measurements, generated by plane waves. We present here a way to handle the inhomogeneous background problem by the means of a constrained optimization approach; in the lines of the inf criterion from the factorization method for constant backgrounds. We show that both cost function and constraints present a simple form that is easy to compute. They can thus be treated by many well-known optimization methods, and we numerically illustrate four of them. © 2015 Taylor & Francis
Estecahandy M.,Total S.A. |
Bordes L.,UPPA |
Collas S.,Total S.A. |
Proceedings - Annual Reliability and Maintainability Symposium | Year: 2015
In the oil and gas industry, obtaining accurate reliability estimators on safety barriers is an important issue that can lead to very long computing times. To address this issue, we propose an extension of a truncation method and we introduce a new computational technique called Dissociation method. Through different numerical examples, we observe a significant improvement of the results obtained on simple Petri net models when applying these Monte Carlo acceleration methods. © 2015 IEEE.