Paralic confinement: models and simulations

International audienceThis paper deals with the concept of confinement of paralic ecosystems. It is based on a recent paper that presents a modelling procedure in order to compute the confinement field of a lagoon. Here, we improve the existing model in order to account for tide oscillations in any kind of geometry such as a non-rectangular lagoons with a non-flat bottom. The new model, that relies on PDEs rather than ODEs, is then implemented thanks to the finite element method. Numerical results confirm the feasibility of confinement studies thanks to the introduced model.Cet article traite de la modélisation du confinement dans des écosystèmes paraliques. Il se base sur un travail récent dans lequel on trouve un modélisation qui permette de simuler le confinement dans des géométries simples. Ici, on améliore le modèle existant afin de permettre la prise en compte de la marée dans un lagon dont la géométrie est quelconque, avec un fond non nécessairement plat. Notre nouveau modèle, qui repose sur des équations aux dérivées partielles, est alors implémenté numériquement grâce à la méthode des éléments finis. Les résultats numériques confirment la faisabilité d'une étude du confinement grâce au modèle proposé

Modeling the wind circulation around mills with a Lagrangian stochastic approach

This work aims at introducing model methodology and numerical studies related to a Lagrangian stochastic approach applied to the computation of the wind circulation around mills. We adapt the Lagrangian stochastic downscaling method that we have introduced in [3] and [4] to the atmospheric boundary layer and we introduce here a Lagrangian version of the actuator disc methods to take account of the mills. We present our numerical method and numerical experiments in the case of non rotating and rotating actuator disc models. We also present some features of our numerical method, in particular the computation of the probability distribution of the wind in the wake zone, as a byproduct of the fluid particle model and the associated PDF method

European Loess Records

Considering their distribution, thickness, and complexity around the margins of the Quaternary ice-sheets in the Northern Hemisphere, loess sequences can be considered as one of the best records of global environmental changes on the continents. European loess sequences have been intensively studied for many decades, but increasingly higher stratigraphic resolution and the availability of a growing range of climate proxy indicators has resulted in some notable advances in recent years. Climatic variability has been analyzed at high resolution, based on different proxies

Modéliser les océans du globe

National audienceIl existe, sous la surface de nos océans, un immense réseau de courants marins, véritables tapis roulants des mers, qui transportent des masses d'eau absolument gigantesques. Ces courants à grande échelle, parmi lesquels figure le célèbre Gulf Stream, jouent un rôle primordial dans la dynamique des océans, et bien entendu dans l'équilibre thermo-dynamique de notre planète. Il est donc essentiel de pouvoir les comprendre afin d'anticiper d'éventuels déséquilibres qui pourraient advenir, par exemple, dans le cadre du réchauffement climatique

Determining the Intrinsic Structure of Public Software Development History

Background. Collaborative software development has produced a wealth of version control system (VCS) data that can now be analyzed in full. Little is known about the intrinsic structure of the entire corpus of publicly available VCS as an interconnected graph. Understanding its structure is needed to determine the best approach to analyze it in full and to avoid methodological pitfalls when doing so. Objective. We intend to determine the most salient network topol-ogy properties of public software development history as captured by VCS. We will explore: degree distributions, determining whether they are scale-free or not; distribution of connect component sizes; distribution of shortest path lengths.Method. We will use Software Heritage-which is the largest corpus of public VCS data-compress it using webgraph compression techniques, and analyze it in-memory using classic graph algorithms. Analyses will be performed both on the full graph and on relevant subgraphs. Limitations. The study is exploratory in nature; as such no hypotheses on the findings is stated at this time. Chosen graph algorithms are expected to scale to the corpus size, but it will need to be confirmed experimentally. External validity will depend on how representative Software Heritage is of the software commons.Comment: MSR 2020 - 17th International Conference on Mining Software Repositories, Oct 2020, Seoul, South Kore