A stability based transition prediction criterion for up to Mach 8 hypersonic flows

International audienceLaminar-turbulent boundary layer transition has an important impact on wall heat exchange and friction, especially in case of high speed vehicles. Much work has been done to implement efficient transition prediction tools directly into RANS solvers, mostly in the transonic domain. Current work aims at reaching Mach 8 in case of 2D ideal gas flow with a constant Prandtl number, and to develop a criterion based on stability computations taking into account both first and second modes of instability. Model development followed by a first implementation into a boundary layer code will be presented, followed by simple validations. Although the objective is to take into account pressure gradient effects as well as imposed wall temperatures, the first step presented here will be limited to adiabatic conditions

RANS Simulation of Laminar-Turbulent Transition in Separation Bubbles on Airfoils

International audiencePredicting the location of laminar-turbulent transition, and modelling the transition region inside a separation bubble are two related questions presently limiting the performance of flow simulations. Considering these questions requires both an understanding of the underlying physics and a number of improvements of the available numerical tools. Several airfoils presenting short and long laminar bubbles are considered, trying to define a common approach with an internal prediction of laminar-turbulent transition. Comparisons to existing measurements and current predictions will be presented. Two methods for transition prediction are used with the same elsA numerical platform, transition criteria and the Menter-Langtry approach

Model Configuration And Data Management In The Short-Term Water Information Forecasting Tools

The Short-term Water Information and Forecasting Tools (SWIFT) is a suite of tools for flood and short-term streamflow forecasting, consisting of a collection of hydrologic model components and utilities. Catchments are modeled using conceptual subareas and a node-link structure for channel routing. The tools comprise modules for calibration, model state updating, output error correction, ensemble runs and data assimilation. Given the combinatorial nature of the modelling experiments and the sub-daily time steps typically used for simulations, the volume of model configurations and time series data is substantial and its management is not trivial. SWIFT is currently used mostly for research purposes but has also been used operationally, with intersecting but significantly different requirements. Early versions of SWIFT used mostly ad-hoc text files handled via Fortran code, with limited use of netCDF for time series data. The configuration and data handling modules have since been redesigned. The model configuration now follows a design where the data model is decoupled from the on-disk persistence mechanism. For research purposes the preferred on-disk format is JSON, to leverage numerous software libraries in a variety of languages, while retaining the legacy option of custom tab-separated text formats when it is a preferred access arrangement for the researcher. By decoupling data model and data persistence, it is much easier to interchangeably use for instance relational databases to provide stricter provenance and audit trail capabilities in an operational flood forecasting context. For the time series data, given the volume and required throughput, text based formats are usually inadequate. A schema derived from CF conventions has been designed to efficiently handle time series for SWIFT

L'environnement : une priorité pour l'agriculture : traiter et recycler les déchets

L'Institut de Recherche pour le Développement (IRD) a pour objectif la conduite de recherches avec des partenaires scientifiques des pays du Sud sur des thèmes importants pour le développement de ces pays. Depuis une quinzaine d'années, la dépollution et la valorisation des déchets agricoles et agro-industriels constituent l'un des trois principaux thèmes de recherche des microbiologistes regroupant leurs activités au sein d'un Programme de l'IRD intitulé "Utilisation de la biodiversité microbienne pour la valorisation des ressources tropicales". Ces recherches sont orientées d'une part vers les activités microbiennes anaérobies et la méthanisation, et d'autre part vers les processus microbiens dits de "fermentation en milieu solide" (FMS) impliquant principalement des champignons et des groupes bactériens tels que les bactéries lactiques. Ces deux orientations conditionnent le classement en trois grands groupes des résidus agricoles et agro-industriels pouvant constituer une source de pollution importante dans les pays du Sud et du Nord. Différents exemples de projets de recherche achevés ou en cours sont résumés en indiquant pour chacun d'eux (1) la nature du problème, (2) l'approche microbiologique du problème et (3) l'état de la valorisation pratique de ces résultats. Les recherches à l'IRD sur la méthanisation de sous-produits agricoles et agro-industriels tropicaux ont initialement été orientées vers la biodépollution. Les premiers travaux ont utilisé des consortiums microbiens non définis provenant de différents écosystèmes et adaptés aux produits à dépolluer. Ce n'est que récemment qu'un inoculum caractérisé a été utilisé avec succès. Ces travaux ont débouché soit sur la valorisation en milieu industriel, soit sur des essais en cours à l'échelle pilote... (D'après le résumé d'auteur

Systèmes de production et transformations de l'agriculture : essai de bilan des travaux du Département d'économie et de sociologie rurales

*Station d'Economie et de Sociologie rurales 65 rue de Saint-Brieuc 35042 RENNES Cedex (FRA) Diffusion du document : Station d'Economie et de Sociologie rurales 65 rue de Saint-Brieuc 35042 RENNES Cedex (FRA)Le projet agréé par le Conseil Scientifique comportait en fait deux objectifs étroitement liés : faire le point sur les recherches du Département ESR en matière de systèmes, de production agricoles ; à travers ce bilan, rendre compte du débat,'en cours depuis plusieurs années, sur les formes prises par la modernisation de l'agriculture,débat qui s'exprime par exemple au travers des couples : productivisme-antiproductivisme, modèles dominants-modèles alternatifs, systèmes intensifs-systèmes extensifs, etc

Screening for cardiovascular risk in the general population: The SPICES implementation survey

BackgroundIn 2019, cardiovascular diseases (CVD) caused 32% of deaths worldwide. The SPICES survey involved five countries in an international primary CVD prevention implementation study in the general population. The French SPICES survey was implemented in the Centre Ouest Bretagne area (COB), which is a rural, economically deprived, medically underserved territory with high cardiovascular mortality. A CVD screening in the general population was needed to select the implementation population without overburdening family practitioner (FP) workforces. The efficacy and the replicability of such a screening were unknown. The aims of this study were to identify the characteristics of the individuals undergoing CVD risk assessment with the Non-Laboratory Interheart risk score (NL-IHRS), and to identify barriers and explore facilitators when screening the general population.MethodsAn implementation study combining a cross-sectional descriptive study with qualitative interviews was undertaken. The NL-IHRS was completed by trained screeners selected from health students, pharmacists, nurses, and physiotherapists in the area with a dedicated e-tool in sport and cultural events and public places. After the screening, all screener groups were interviewed until theoretical saturation for each group. Thematic analysis was performed using double-blind coding.ResultsIn 5 months, 3,384 assessments were undertaken in 60 different places, mostly by health students. A total of 1,587, 1,309, and 488 individuals were at low, moderate, and high CVD risk. Stressed or depressed individuals were remarkably numerous (40.1 and 24.5% of the population, respectively). Forty-seven interviews were conducted. The main facilitators were willingness of the population, trust between screeners and the research team, and media publicity. The main barriers were lack of motivation of some screeners, some individuals at risk, some stakeholders and difficulties in handling the e-tool.ConclusionThe efficacy of CVD risk screening while using mostly health students was excellent and preserved the FP workforce. Replicability was highly feasible if research teams took great care to establish and maintain trust between screeners and researchers. The e-tools should be more user-friendly

Single-scan multiplane phase retrieval with a radiation of terahertz quantum cascade laser

Terahertz phase retrieval from a set of axially separated diffractive intensity distributions is a promising single-beam computational imaging technique that ensures the obtention of high spatial resolutions and phase wavefronts, but remains restricted by time-consuming data acquisition processes. In this work, we have adopted an approach, relying on the radiation of a quantum cascade laser and the implementation of an express single-scan measurement of intensity distributions through the continuous on-the-go displacement of a high-sensitivity antenna-coupled microbolometer sensor array. In addition to the simplicity of this practical implementation and the minimization of measurement times, such an approach overcomes the problem of preliminary optimal selections of transverse intensity distributions used in the iterative phase retrieval algorithm and guarantees the required data diversity for high-quality wavefront reconstruction

Challenges In The Simultaneous Development And Deployment Of A Large Integrated Modelling System

Many of our natural resource management issues cannot be adequately informed by a single discipline or sub-discipline, and require an integration of information from multiple natural and human systems. As we are unable to observe and monitor more than a few important indicators there is a strong reliance on supplementing observed information with modelled information. Following a period of record drought in the 1990’s, the Australian government recognised the need for better quality, more integrated, and nationally consistent water information. The Australian Water Resources Assessment system (AWRA) is an integrated hydrological modelling system developed by CSIRO and Australian Bureau of Meteorology (the Bureau) as part of the Water Information Research and Development Alliance (WIRADA) to support the development of two new water information products produced by the Bureau. This paper outlines the informatics, systems implementation and integration challenges in the development and deployment of the proto-operational AWRA system. A key challenge of model integration is how you access and repurpose data, how you reconcile semantic differences between both models and disparate input data sources, how you translate terms when passing between often conceptually different modelling components and how you ensure consistent identity between real world objects. The rapid development of AWRA and simultaneous transfer to an operational environment also raised many additional challenges, such as supporting multiple technologies and differing development rates of each model component, while still maintaining a working system. Additionally the continentally sized model extent, combined with techniques relatively new to the hydrologic domain, such as data assimilation and continental calibration, have introduced significant computational overheads. While an in-house fit for purpose operational build of AWRA is currently under development within the Bureau, the research challenges undertaken early in AWRA’s development still hold many valuable lessons. We have found that the use of file standards such as NetCDF, services-based modelling, and scientific workflow technologies such as ‘The WorkBench’ combined with strong model governance has mostly reduced the burden of system development and deployment and exposes some important lessons for future integrated modelling and systems integration efforts