Rapport d’expertise de la procédure de qualification des équipements ILS. Limites et Probabilités de confiance.

L'objet de cette étude est de clarifier certains passages du rapport "DERA/WSS/WX1/CR 980799/2.3 ILS Certification Requirements". Nous étudions en particulier le paragraphe 3.3 "Confidence Limits for Sequential Tests" p.28-34 et le paragraphe 2 de l'appendice D, p.69-72

Study of the ILS certification process. Confidence limits and probabilities.

The purpose of this study is to explain some parts of the DERA report DERA/WSS/WX1/CR 980799/2.3. "ILS Certification Requirements" (Ref. 2). We mainly study section 3.3 "Confidence Limits for Sequential Tests" p.28-34 and section 2 of the appendix D, p.69-72

Les réseaux entrepreneuriaux en zone de faible densité

International audienc

Les réseaux entrepreneuriaux en zone de faible densité

International audienc

Rapport concernant la possibilité d’utiliser le MTBO théorique dans la procédure de qualification des équipements ILS

La société STNA participe à la certification des équipements utilisés pour la navigation aérienne. Dans ce cadre la division 3R s’intéresse aux équipements ILS. Ces équipements, situés au sol, sont utilisés lors de l’atterrissage. Leur objectif de fiabilité est fonction de la catégorie de l’équipement. Cet objectif est caractérisé par une valeur de MTBO, appelée MTBO objectif. Cette valeur est déduite de l’étude par arbre de défaillance du système complet. La démonstration de l’atteinte de cet objectif est réalisée à l’aide de tests séquentiels dont la durée doit au moins être supérieure à 1 an (pour prendre en compte les différents environnements d’exploitation). Ces tests sont décrits dans la norme MIL-HDBK-781. La mise en œuvre de cette démarche demande un temps de test jugé excessif (plus de 2 ans), aussi des études ont été menées pour tenter de réduire cette durée de test. La piste explorée jusqu’à présent consiste à augmenter le niveau du risque du consommateur. Le STNA souhaite dans un premier temps étudier cette piste en faisant apparaître toutes les hypothèses sous-jacentes, puis dans un second temps regarder si d’autres pistes sont possibles

How to efficiently handle 300 projects on Model Representations and Analysis?

International audienceThe current international trend of grouping together several engineering institutions leads to large-scale student classes. This raises numerous challenges for spreading the engineering science at a broad range but also offers the opportunity to build the premises for up-to-date educational innovations. The aim of this paper is to propose a modular and easily extendable database, with a user-friendly interface, allowing to handle a multitude of student projects in the field of engineering. In order to demonstrate the efficiency of the proposed framework, a case study on the implementation of the database for handling 300 projects in the context of the course Model Representations and Analysis given at CentraleSupélec to 900 students during the school year 2021-2022 is reported

How to efficiently handle 300 projects on Model Representations and Analysis?

International audienceThe current international trend of grouping together several engineering institutions leads to large-scale student classes. This raises numerous challenges for spreading the engineering science at a broad range but also offers the opportunity to build the premises for up-to-date educational innovations. The aim of this paper is to propose a modular and easily extendable database, with a user-friendly interface, allowing to handle a multitude of student projects in the field of engineering. In order to demonstrate the efficiency of the proposed framework, a case study on the implementation of the database for handling 300 projects in the context of the course Model Representations and Analysis given at CentraleSupélec to 900 students during the school year 2021-2022 is reported

Lagrangian flow properties along filament-like structures and its impact on the distribution and composition of phytoplankton

Trabajo presentado en la Ocean Sciences Meeting, celebrada en San Diego del 16 al 21 de febrero de 2020.Physical factors induced by the turbulent flow play a crucial role in regulating marine ecosystems. Here we show that the combination of complementary Lagrangian diagnostics provides an improved description of the geometrical and kinetic properties of the flow, which facilitates the interpretation of physical mechanisms affecting phytoplankton composition, dynamics and patchiness. The influence of small-scale dynamics (O(3.5-25) km, i.e. spanning upper submesoscale and mesoscale processes) on phytoplankton in surface waters derived from satellite chlorophyll-a (chl a) is studied using Lagrangian metrics computed from High-Frequency Radar currents over the Ibiza Channel. Attracting small-scale flow structures are associated to filaments of accumulated negative divergence where particles and chl a standing stocks cluster. Regions of accumulated positive divergence, representing large accumulated upward vertical velocities and suggesting accrued injection of subsurface nutrients, match areas with large chl a concentrations. Furthermore the composition of phytoplankton community was studied regarding the sustained kinematic properties of the flow during the formation of an intense filament. In this regard new metrics accounting for the Lagrangian evolution of the turbulent and topological properties along fluid parcel trajectories have been developed. Here we provide observational evidences, during the SHEBEX cruise (May 2015) in the western Mediterranean and altimetry-derived Lagrangian computations, that fluid parcels associated with high Lagrangian turbulent kinetic energy and Lagrangian positive vorticity host higher relative abundance of larger pennate diatoms (i.e. Pseudo-nitzschia spp). Our findings indicate that the combination of these diagnostics provides an improved description of the turbulent dynamics showing that the Lagrangian properties of the flow have important biological consequences.Peer reviewe

Aerosol composition at EMEP remote sites in France : mass balance and de-weathered trends of PM2.5 and its main components

International audienceAtmospheric particulate matter with an aerodynamic diameter < 2.5 µm (PM2.5) is associated with adverse effects on the climate system, the human health, vegetation and the ecosystems. The World Health Organization (WHO) lowered the guideline limit for PM2.5 in autumn 2021 and this is exceeded in many regions including rural and remote areas in mainland Europe. Measurements of the chemical composition of PM2.5 is essential to assess the sources which contribute to PM2.5 mass concentrations and to further design meaningful policies to tackle sources at their origin.Here we report 6 years (2014- 2020) of PM2.5 mass and chemical speciation at five remote sites across France belonging to the EMEP network (European Monitoring and Evaluation Programme). The seasonal and spatial variability of aerosol composition and source contributions based on the proximity of sources and long-range transport are discussed. Trends in PM2.5 and the main components at the five locations were evaluated by means of random-forest modelling coupled with a de-weathering algorithm. This approach is advantageous as resulting trends are driven by changes in emission or atmospheric processes and not by changes in weather conditions and/or long-range transport patterns. Random-forest regression modelling was built using meteorological data, backtrajectory information and temporal variables at each site and quantified the most important factors that explain PM2.5 concentrations at remote rural areas in France.All sites observed statistically significant downward trends in PM2.5 at a rate of -4 to -9% year-1 for the period 2014 - 2020. The decrease in PM2.5 concentrations was mostly explained by changes in the secondary inorganic species (sulphate, nitrate and ammonium) and not by changes in primary PM2.5 emissions. The variability in trends in PM2.5 and components observed across the sites is discussed with their implications for policy makers