Search

International audience; This paper evaluates a set of complex cells with different transistor arrangements that implement the same logic function. These cells were evaluated under nominal conditions and with gate variability at layout level. The purpose is to verify what topology is more appropriate to increase the robustness of cells regarding the process variability issues. Results emphasize the importance of investigating the effects caused by process variability in FinFET technologies, as the electrical characteristics of circuits suffer significant changes. In general, the best choice is to use the network that the transistor in series is as far as possible to the output node. However, a trade-off needs to be done due to performance and power consumption penalties.

International audience; This paper presents a design strategy to reduce the impact of process variations and soft error susceptibility in FinFET circuits. The mitigation is provided by connecting a Schmitt Trigger at the logic gate output. The improvements in power and delay variability can reach up to 32.6% and 42.1%, respectively, with logic cells almost immune to soft error even at the near-threshold regime. When compared with other circuit-level methods such as sleep transistor, decoupling cells, and transistor reordering, on average, the Schmitt Trigger technique is at least 6%, 8%, and 10.5% more robust to process variability, respectively.

International audience; This paper investigates the construction of a metamodel for coastal flooding early warning at the peninsula of Gâvres, France. The code under study is an hydrodynamic model which receives time-varying maritime conditions as inputs. We concentrate on Gaussian pocess metamodels to emulate the behavior of the code. To model the inputs we make a projection of them onto a space of lower dimension. This setting gives rise to a model selection methodology which we use to calibrate four characteristics of our functional-input metamodel: (i) the family of basis functions to project the inputs; (ii) the projection dimension; (iii) the distance to measure similarity between functional input points; and (iv) the set of functional predictors to keep active. The proposed methodology seeks to optimize these parameters for metamodel predictability, at an affordable computational cost. A comparison to a dimensionality reduction approach based on the projection error of the input functions only showed that the latter may lead to unnecessarily large projection dimensions. We also assessed the adaptability of our methodology to changes in the number of training and validation points. The methodology proved its robustness by finding the optimal solution for most of the instances, while being computationally efficient.

International audience; In this study, we investigate the effect of single steps inside the fuel grains of typical hybrid rocket motors numerically. Steps can be a promising candidate to increase the regression rate of hybrid engines. We show that simulations on simplified geometries yield surprisingly close numerical regression rate profiles when compared to experimental data. Moreover, there is no necessity to calculate the progression of the fuel port at different time steps, as a single simulation on the average diameter can match the experiments sufficiently well. This observation allows for larger parametric studies on optimal positioning of the steps while limiting computational resources. The potential to increase the average regression rate through steps can be predicted numerically, and the simulations are following the same trend as the experiments. The augmented mixing and heat transfer inside the turbulent boundary layer can be predicted. It is concluded that backward facing steps increase the regression rate proportional to the step height up to 10 mm, and are preferably utilized upstream. For forward facing steps, the regression rate augmentation is saturated starting with 5 mm step height, and the position should be further downstream.

Let X -> Y be a fibration whose fibers are complete intersections of two quadrics. We develop new categorical and algebraic tools---a theory of relative homological projective duality and the Morita invariance of the even Clifford algebra under quadric reduction by hyperbolic splitting---to study semiorthogonal decompositions of the bounded derived category of X. Together with new results in the theory of quadratic forms, we apply these tools in the case where X -> Y has relative dimension 1, 2, or 3, in which case the fibers are curves of genus 1, Del Pezzo surfaces of degree 4, or Fano threefolds, respectively. In the latter two cases, if Y is the projective line over an algebraically closed field of characteristic zero, we relate rationality questions to categorical representability of X., 43 pages, changes made and some material added and corrected in sections 1, 4, and 5; this is the final version accepted for publication at Journal de Math\'ematiques Pures et Appliqu\'ees

International audience; Traditionally, complex gates are adopted to reduce area, delay and power consumption. However, they can introduce challenges related to a robustness that might be avoided with more regular and basic cell rules. This work shows the relation between gate mapping and process variability robustness in FinFET technology, exploring for the same circuit, a complex-gate design and a basic gates one. The transistor arrangement adopted can vary by up to 30% the delay robustness, around 18% the robustness to the power consumption and 25% the Power-Delay-Product deviation.

International audience; This work presents comparisons between numerical simulations and secondary electron emission yield measurements. The impact on the secondary electron emission yield of a growing graphite layer deposited on copper substrates is analyzed. The numerical simulations confirm experimental observations showing that a very thin coating deposit, with a thickness of few nm, can affect significantly the emission yield of an irradiated material. Beyond 5 nm thickness, the surface material alone drives the secondary emission.; Ce travail présente des comparaisons entre des simulations numériques et des mesures de rendement d'émission d'électrons secondaires. L'impact sur le rendement d'émission des électrons secondaires d'une couche croissante de graphite déposée sur des substrats de cuivre est analysé. Les simulations numériques confirment les observations expérimentales montrant qu'un dépôt de revêtement très fin, d'une épaisseur de quelques nm, peut affecter de manière significative le rendement d'émission d'un matériau irradié. Au-delà de 5 nm d'épaisseur, le matériau de surface seul dirige l'émission secondaire.

Objective: To evaluate the educational impact of a pilot MOOC (Massive Open Online Course), validated by the French College of Urology Teachers (FCUT), on the surgical technique of kidney transplantation.Materials and methods: We developed a MOOC on the surgical technique of kidney transplantation, based on a video of a surgical procedure, performed by an expert surgeon. The MOOC has been validated by the FCUT. We have created 2 student groups: 1) MOOC-pre-QCM group: visualization of the MOOC then answer to the MCQs and satisfaction questions; 2) MOOC-post-QCM group: answer to the MCQs then visualization of the MOOC then answers to the satisfaction questions. In total, 20 MCQs on the kidney transplantation technique were completed by the 2 groups. The answers were anonymous.Results: A total of 142 people answered the MCQs (MOOC-pre-QCM group (n=66) and MOOC-post-QCM group (n=76)). Twenty-nine percent (41/142) of the participants were fellows and 71 % (101/142) were residents. The proportion of fellows and residents was identical between the 2 groups. The rate of correct answers to the 20 MCQs was statistically higher in the MOOC-pre-QCM group, compared to the MOOC-post-QCM group (88.6 % versus 73.3 %, P, ObjectifÉvaluer l’impact pédagogique d’un MOOC (Massive Open Online Course) pilote, validé par le Collège français des enseignants en urologie (CFEU), sur la technique chirurgicale de transplantation rénale.Matériel et méthodesNous avons réalisé un MOOC sur la technique chirurgicale de transplantation rénale, à partir d’une vidéo d’une intervention chirurgicale, réalisée par un chirurgien expert. Le MOOC a été validé par le CFEU. Nous avons créé 2 groupes d’étudiants : 1) groupe MOOC-pré-QCM : visualisation du MOOC, puis réponse aux QCM et aux questions de satisfaction ; 2) groupe MOOC-post-QCM : réponse aux QCM, puis visualisation du MOOC, puis réponse aux questions de satisfaction. Au total, 20 QCM sur la technique transplantation rénale ont été remplis par les 2 groupes. Les réponses étaient anonymes.RésultatsAu total, 142 personnes ont répondu aux QCM (groupe MOOC-pré-QCM (n = 66) et groupe MOOC-post-QCM (n = 76)). 29 % (41/142) des participants étaient des CCA ou assistants et 71 % (101/142) étaient des internes. La proportion de CCA/assistants et d’internes était identique entre les 2 groupes. Le taux de réponses correctes aux 20 QCM était statistiquement supérieur dans le groupe MOOC-pré-QCM, en comparaison au groupe MOOC post-QCM (88,6 % contre 73,3 %, p < 0,0001). Au total, 91 % des étudiants ont trouvé le MOOC « Très Utile » ou « Utile ». La médiane de la note du MOOC, donnée par les étudiants, était de 8/10.ConclusionCette étude a montré un impact positif du MOOC sur les connaissances théoriques de la technique chirurgicale de transplantation rénale. Ce MOOC pourrait servir de projet pilote pour le développement d’autres MOOC sur la chirurgie urologique.Niveau3.

International audience; We describe an experimental platform for testing the DarkO tail-sitter drone in an open wind tunnel experiment. The DarkO convertible UAV is developed and 3D printed at the Ecole Nationale de l'Aviation Civile (ENAC), in Toulouse (France). The objective of the experimental platform is to allow testing control laws in a realistic and secure context. We propose a test bench with a single degree of freedom corresponding to the drone pitch axis. We design a linear proportional/integral feedback hovering stabilizer in the presence of constant wind, and we illustrate its effectiveness in stabilizing a hovering position through experimental results.

International audience; The melting process is studied for the case of snowflakes of aggregate type. Snowflakes are placed in the center of an acoustic levitator with a warm air flow. The evolution of the shape of the snowflake is recorded over time by a camera and the total melting time is measured. A model is proposed to describe the melting process. It is based on a simplified 3D geometric representation of the snowflake (spheroidal shape for the convex hull) and an accurate estimation of its bulk density throughout the melting process. This allows taking into account the very important change of the shape of the aggregate during the melting step and thus to be able to predict the total melting time with a much better accuracy than the existing models.

International audience; This article describes an experimental investigation into the heat fluxes generated by the combustion of AP/HTPB solid propellant samples inside 1-MPa pressurized combustion chambers. Fluxmeters developed at ONERA and recently improved were used to measure the local heat flux densities. Two kind of fluxmeters were used: total fluxmeters for which the convective and the radiative components are measured and radiative fluxmeters for which the convective component is suppressed by the use of a sapphire window mounted on top of the fluxmeter. Additionally, the flame was visualized by a narrow-band filtered IR camera which provided quantitative and spatially resolved radiance field. From the IR camera recordings, a radiative heat flux equivalent to that measured by the radiative fluxmeters was constructed by means of the integration over the fluxmeters' collection volumes of the spectrally equivalent radiance. A satisfactory agreement is thus found between the two radiative heat flux measurement methods.; Cet article décrit une étude expérimentale sur les flux de chaleur générés par la combustion d'échantillons de propergol solide AP/HTPB à l'intérieur de chambres de combustion pressurisées de 1-MPa. Des fluxmètres développés à l'ONERA et récemment améliorés ont été utilisés pour mesurer les densités locales de flux de chaleur. Deux types de fluxmètres ont été utilisés : les fluxmètres totaux pour lesquels les composantes convectives et radiatives sont mesurées et les fluxmètres radiatifs pour lesquels la composante convective est supprimée par l'utilisation d'une fenêtre en saphir montée sur le dessus du fluxmètre. En outre, la flamme a été visualisée par une caméra IR à bande étroite filtrée qui a fourni un champ de radiance quantitatif et spatialement résolu. À partir des enregistrements de la caméra IR, un flux de chaleur radiative équivalent à celui mesuré par les fluxmètres radiatifs a été construit par l'intégration de la radiance spectralement équivalente sur les volumes de collecte des fluxmètres. Un accord satisfaisant est donc trouvé entre les deux méthodes de mesure du flux de chaleur radiative.

The prediction of the on-ground risk caused by re-entering space debris requires accurate and computationally affordable models to compute wall heat flux and pressure coefficient C p at every stage of the reentry. Such models already exist for the wind area of the debris, i.e the area directly impinged upon by fictitious lines parallel to the incoming flow. But the heat flux and C p are often neglected in the shadow area, even though they can be relatively high for certain shapes of debris. The present work focuses on developing reduced order models for heat flux and C p distributions in the shadow area of space debris, for hypersonic continuous flow conditions. We identified four phenomena which appear in the shadow area and cause relatively high levels of these aerodynamic quantities (attached flow, detached flow with fluid reattachment, detached flow with solid reattachment and shock–shock interactions). Models were developed for the heat flux and C p distributions caused by attached flows on the lee side of cylindrical geometries using the Proper Orthogonal Decomposition (POD) and interpolation method. Using this method, it is possible to reduce the number of required data by efficiently exploring the parameters domain of variation. The sample points were chosen thanks to an adaptive design of experiments, and the input data for the models were obtained by 3D Navier–Stokes computations of the flow around cylinders at incidence. The analysis of the computational results highlighted the influence of the Reynolds number based on the cylinder diameter R e D , ∞ on the heat flux and pressure distributions. Reduced-order models were created for three input parameters (length L , diameter D and angle of attack α ) and fixed incoming flow conditions, using the POD and interpolation method, and then were extended to other upstream hypersonic continuous flow conditions by more classical approaches based on non-dimensional quantities. Finally, the reentry trajectories of two different cylindrical debris were computed with and without the new models developed, to demonstrate their influence on the integrated heat flux received by the debris during their reentry, and therefore on their survival rate.

International audience; In this paper, we propose a new piecewise polynomial model (PwPM) for the modelling of an Unmanned Aircraft System (UAS) aerodynamic coefficients over a wide flight envelope, where they are characterized by nonlinear and hysteresis phenomena. An associated identification method using Constrained Least Squares (CLS) is then presented and successfully applied to experimental data obtained from wind tunnel measurements. The resulting fitting is finally compared with the similar piecewise models PWPFIT and AERODAS, showing a greater precision in its modelling, while maintaining their relative simplicity and computation performance.

This work is concerned with the construction and the hp non-conforming a priori error analysis of a Discontinuous Galerkin DG numerical scheme applied to the hypersingular integral equation related to the Helmholtz problem in 3D. The main results of this article are an error bound in a norm suited to the problem and in the L 2 -norm. Those bounds are quasi-optimal for the h -convergence and the p -convergence. Various formulation choices and penalty functions are theoretically discussed. In particular we show that a penalty function of the shape h 2 p leads to a quasi-optimal convergence of the scheme. Some numerical experiments confirm the expected rates of convergence and the effect of the penalty function.

International audience; Software architectures for autonomous systems are generally structured with 3 layers: a decisional layer managing autonomous reasoning, a functional layer managing reactive tasks and processing, and an executive layer bridging the gap between both. The executive layer plays a central role, as it links high-level tasks with lowlevel processing, and is generally responsible for the robustness or the fault-tolerance of the overall system. In this paper, we propose a development process for such an executive layer that emphasizes on the dependability of this layer. To do so, we structure the executive layer using skills, that are formally defined using a specific language, and we then provide some tools to verify these models, generate some code, and a methodology to assess the fault-tolerance of the resulting architecture.; Les architectures logicielles pour les systèmes autonomes sont généralement structurées en 3 couches : une couche décisionnelle qui gère le raisonnement autonome, une couche fonctionnelle qui gère les tâches réactives et le fonctionnement, et une couche d'exécution qui fait le lien entre les deux. Cette dernière joue un rôle central, car elle relie les tâches de haut niveau aux traitements de bas niveau, et est généralement responsable de la robustesse ou de la tolérance aux pannes du système global.Dans cet article, nous proposons un processus de développement pour une couche d'exécution qui met l'accent sur la fiabilité de celle-ci. Pour ce faire, nous structurons la couche d'exécution en utilisant des "skills", qui sont formellement définis à l'aide d'un langage dédié, et nous fournissons ensuite des outils pour vérifier ces modèles, générer du code, et une méthodologie pour évaluer la tolérance aux pannes de l'architecture résultante.

International audience; Multipactor voltage threshold charts and scaling laws for 30 Ω circular coaxial geometries, relevant to the WEST Ion Cyclotron Resonance Heating antennas, are reproduced using a developed multipactor decision-making algorithm relying on Spark-3D electron time-evolution data. The developed methodology is validated by comparing the simulated multipactor powers to the measured multipactor power thresholds, for a 50 Ω coaxial geometry. The effects of the conditioning, for a WEST antenna-relevant surface sample, on the total electron emission yield and surface properties are studied. The consequences of the conditioning phase on the multipactor voltage thresholds for coaxial transmission lines of 30 Ω and 50 Ω characteristic impedance are also highlighted. It is shown that preliminary baking and conditioning suppress or reduce the range in which multipactor can be triggered.

International audience; Human leukocyte antigen (HLA) mismatching and minimization of immunosuppression are two major risk factors for the development of de novo donor-specific antibodies, which are associated with reduced kidney graft survival. Antibodies do not recognize whole HLA antigens but rather individual epitopes, which are short sequences of amino acids in accessible positions. However, compatibility is still assessed by the simple count of mismatched HLA antigens. We hypothesized that the number of mismatched epitopes, or ("epitope load") would identify patients at the highest risk of developing donor specific antibodies following minimization of immunosuppression. We determined epitope load in 89 clinical trial participants who converted from cyclosporine to everolimus 3 months after kidney transplantation. Twenty-nine participants (32.6%) developed de novo donor specific antibodies. Compared to the number of HLA mismatches, epitope load was more strongly associated with the development of donor specific antibodies. Participants with an epitope load greater than 27 had a 12-fold relative risk of developing donor-specific antibodies compared to those with an epitope load below that threshold. Using that threshold, epitope load would have missed only one participant who subsequently developed donor specific antibodies, compared to 8 missed cases based on a 6-antigen mismatch. DQ7 was the most frequent antigenic target of donor specific antibodies in our population, and some DQ7 epitopes appeared to be more frequently involved than others. Assessing epitope load before minimizing immunosuppression may be a more efficient tool to identify patients at the highest risk of allosensitization.

International audience; Background & aims: Before antiviral therapy, kidney transplant recipients infected with hepatitis B virus (HBV) or hepatitis C virus (HCV) had poor outcomes. Since the 90s, nucleos(t)ide analogues have been widely used in HBV-infected patients, while interferon-based therapy was rarely used in HCV-infected patients. The aim of this study was to assess the impact of HBV and HCV on patient and graft survival, according to viral replication status.Methods: Data from January 1993 to December 2010 were extracted from the French national database CRISTAL. A total of 31,433 kidney transplant recipients were included, of whom 575, 1,060 and 29,798 had chronic hepatitis B, C, or were not infected, respectively.Results: Ten-year survival was lower in HCV-infected (71.3%) than in HBV-infected (81.2%, p = 0.0004) or non-infected kidney transplant recipients (82.7%, p

This study proposes a new inverse method to estimate the bed topography elevation beneath glaciers flows from surface observations (altimetry elevations and InSAR velocities) and (very) sparse depth measurements (e.g. acquired during airborne campaigns). To do so an original form of depth-integrated flow equations (long-wave assumption) is derived. The latter are valid for highly to mildly-sheared regimes hence including moderately fast flows; varying internal thermal profiles are taken into account. The inverse problem is particularly challenging since the surface signatures integrate the bottom features (bed elevation and friction–slip amount) plus the internal deformation. The first key ingredient of the inverse method is the derivation of this non-isothermal Reduced Uncertainty (RU) version of the classical SIA equation (lubrication type model for generalised Newtonian fluids) by intrinsically integrating the surface measurements in the formulation. This resulting multi-physics RU-SIA equation contains a unique uncertain dimensionless parameter only (the parameter γ ). The next key ingredient is an advanced Variational Data Assimilation (VDA) formulation combined with a purely data-driven extension of γ based on the trend observed in the (sparse) depth measurements (e.g. along the flight tracks). The resulting inverse method provides the first physical-based depth estimations in mildly-sheared mildly-slippery shallow flows. In poorly monitored ice-sheet areas (e.g. in Antarctica), the resulting estimations are noticeably less uncertain than the current ones (in particular compared to those obtained by gravimetry inversions). The present numerical experiments and experimental sensitivity analyses demonstrate the reliability of this new RU-SIA equation and the robustness of the inverse method. In other respect, the RU-SIA equation may provide a-posteriori estimations of the thermal boundary layer at bottom.

International audience; Three Reynolds-Stress Models (RSMs) have been benchmarked on industrial configurations with aeronautical applications. The models are first compared on a zero-pressure-gradient boundary layer, which highlights the differences in the near-wall approaches of the models. Results are then analyzed for the Skåre & Krogstad adverse-pressure-gradient boundary layer and the Common Research Model (CRM) aircraft for two Reynolds numbers. Both cases display improvements in using RSMs over the eddy-viscosity Spalart-Allmaras model. Two of the considered second-moment closures better predict the boundary layer growth and its shape factor in the Skåre & Krogstad test case, and all noticeably improve the drag-due-to-lift in the CRM case.

International audience; This work addresses the challenge of providing precise runway-relative position, velocity and orientation reference to a landing aircraft based on monocular camera and low-cost inertial sensor data complemented by barometric sensor readings. GPS information is excluded from this sensor set because it is intended to use the developed estimator for GPS and Instrumental Landing System fault detection. The characteristic size of the runway is assumed to be unknown and it is estimated run-time after verifying global observability of the nonlinear system. The delay caused by image processing is dealt with a delayed-Error-State Kalman Filter (ESKF). This algorithm considers dynamic propagation of the image information between acquisition and application forward in time thus the delay does not appear in the system dynamics. The first evaluation of the estimator is done for ideal simulated data to verify applicability of the delayed-ESKF and its flawless implementation. Then more realistic simulated data with sensor biases and noise is considered to verify closer to realistic performance and bias estimation precision. Finally, the estimator is tested with real flight data collected in the VISION EU H2020 research project. Estimation results are compared to GPS SBAS-based data and Airbus precision tolerances showing satisfactory performance. The methodological contribution of the paper is the unique combination of existing methods and ideas leading to a new solution proven to work satisfactorily even with real flight data.

International audience; A generalized Scharfetter-Gummel method is proposed to construct the numerical flux for one-dimensional drift-diffusion equations. Instead of taking a constant approximation of the flux as Scharfetter and Gummel did in [1], we consider a p-degree polynomial with p ≥ 1. The high order moments of the approximating flux function serve as intermediaries to bring numerical correction to the Scharfetter-Gummel flux, that the other end turns out to be the solution derivatives. Therefore, local solution reconstructions are required. The resulting schemes are high order and discretize at the same time the convective and diffusive fluxes without having to employ separately different methods to do so. The new schemes with p = 1 and p = 2 are employed to simulate atmospheric pressure discharge where they are applied to the continuity equations for electrons and ions, and solved simultaneously with Poisson's equation. Numerical results indicate that our method are robust and highly accurate.

International audience; Most attitude control scenarios are highly affected by fuel slosh dynamics that must be carefully taken into account to preserve pointing accuracy. Since such dynamics are not easily predictable, standard strategies consist of bounding the performances of the control system to avoid interactions between the rigid dynamics of the spacecraft and the oscillating liquid motion inside the fuel tank. Thanks to a recently developed control-oriented CFD-based fuel slosh model, an alternative approach is evaluated in this paper. It is based on a reformulation of the slosh effects in the Linear-Parameter-Varying (LPV) framework from which a robust LPV observer is easily derived. The latter is then classically used in a disturbance compensation scheme. The proposed strategy is illustrated on a simple but realistic single axis attitude control scenario for a small satellite using reaction wheels.

International audience; During the development of a complex system, data models are the key to a successful engineering process, as they contain and organize all the information manipulated by the different functions involved in the design of the system. Moreover, these data models evolve throughout the design, as the development raises issues that have to be solved through a restructuration of data organization. But any such data model evolution has a deep impact on the functions that have already being defined.Recent research tries to deal with this issue by studying how complex industrial data models evolve from one version to another and how their data instances co-evolve. Complexity and scalability issues make this problem a major scientific challenge, leading to huge gains in development efficiency. This problem is of particular interest in the field of aeronautics and space systems. Indeed, the development of these systems produces many complex data models associated to the designed systems and/or to the systems under design, hence on the one hand data models are available. On the other hand, it is well known that these systems are developed in the context of collaborative projects that may last for decades. In such projects, specifications together with the associated data models are bound to evolve and engineering processes shall take into account this evolution.Our work addresses the problem of data model evolution in a model-driven engineering setting. We focus on minimizing the impact of model evolution on the system development processes in the specific context on the space engineering area, where data models may involve thousands of concepts and relationships, and we investigate the performance of the model-based development (MBD) approach we propose for data model evolution over two space missions, namely PHARAO and MICROSCOPE.

International audience; Surface soil moisture content (SMC) is known to impact soil reflectance at all wavelengths of the solar spectrum. As a consequence, many semi-empirical methods aim at inferring SMC from soil reflectance, but very few rely on physically-based models. This article presents a multilayer radiative transfer model of soil reflectance called MARMIT (multilayer radiative transfer model of soil reflectance) as a function of SMC given on a mass basis and a method called MARMITforSMC to estimate it from soil reflectance spectra. This model depicts a wet soil as a dry soil covered with a thin film of water. It is used to assess SMC over seven independent laboratory datasets gathered from the literature. A learning phase is required to link the thickness of the water film with the SMC. For that purpose, a sigmoid function, the parameters of which are related to soil physical and chemical properties such as porosity, grain size and mineralogy composition, is fitted. SMC can be inferred with good accuracy (RMSE ≈ 3%) if the learning step is applied soil by soil. The link between SMC and water thickness actually depends on soil texture and chemical composition. If the soils are divided into classes and if the learning phase is applied to a class, the RMSE slightly increases up to 5%. Finally, MARMITforSMC provides lower RMSE than any other existing semi-empirical or physically-based method.

International audience; This paper aims at presenting sensitivity estimators of a rare event probability in the context of uncertain distribution parameters (which are often not known precisely or poorly estimated due to limited data). Since the distribution parameters are also affected by uncertainties, a possible solution consists in considering a second probabilistic uncertainty level. Then, by propagating this bi-level uncertainty, the failure probability becomes a random variable and one can use the mean estimator of the distribution of the failure probabilities (i.e. the " predictive failure probability " , PFP) as a new measure of safety. In this paper, the use of an augmented framework (composed of both basic variables and their probability distribution parameters) coupled with an Adaptive Importance Sampling strategy is proposed to get an efficient estimation strategy of the PFP. Consequently, double-loop procedure is avoided and the computational cost is decreased. Thus, sensitivity estimators of the PFP are derived with respect to some deterministic hyper-parameters parametrizing a priori modeling choice. Two cases are treated: either the uncertain distribution parameters follow an unbounded probability law, or a bounded one. The method efficiency is assessed on two different academic test-cases and a real space system computer code (launch vehicle stage fallback zone estimation).

International audience; The problem of position tracking of a mini drone subject to wind perturbations is investigated. The solution is based on a detailed unmanned aerial vehicle (UAV) model, with aerodynamic coefficients and external disturbance components, which is introduced in order to better represent the impact of the wind field. Then, upper bounds of wind-induced disturbances are characterized, which allow a sliding mode control (SMC) technique to be applied with guaranteed convergence properties. The peculiarity of the considered case is that the disturbance upper bounds depend on the control amplitude itself (i.e. the system is nonlinear in control), which leads to a new procedure for the control tuning presented in the paper. The last part of the paper is dedicated to the analysis and reduction of chattering effects, as well as investigation of rotor dynamics issues. Conventional SMC with constant gains, proposed first order SMC, and proposed quasi-continuous SMC are compared. Nonlinear UAV simulator, validated through in-door experiments, is used to demonstrate the effectiveness of the proposed controls.

International audience; Since the beginning of civil aviation, icing is a severe weather hazard for aircraft operation. In this context, the phenomenon of ice crystal icing has been identified as a risk for flight safety in the recent past. Ice crystals can accrete on warm components such as heated stagnation pressure probes and engine compressor blades. Liquid melt water or additional liquid droplets in the icing cloud enable the ice particles to stick to the component surface and to form a cohesive ice accretion layer. In this paper, we present results of comprehensive icing wind tunnel tests on ice crystal ice accretion together with results of complementary simulations by means of the ONERA icing code IGLOO2D. The experiments show a strong influence of ambient temperature on the icing process. In agreement with literature findings, ice particle sticking ability can be correlated with the ice cloud composition. Correlations between accretion shape and growth rate have been identified. IGLOO2D separates accretion abrasion by particle impact from the efficiency with which those particles stick to the deposit. Comparisons of computational and experimental results indicate that this sticking efficiency has the greatest effect on ice shapes at low Mach numbers, at least for the particle sizes and conditions used in the experiments. The experimental and numerical findings of this study can be considered as complementary to existing knowledge on ice crystal icing. Therefore, the experimental results are provided to an international benchmark of test cases for icing code validation.

It seems no longer possible to produce knowledge, even biological knowledge regardless of social, cultural and economic environments in which they were observed. Therefore never the term “social medicine” or more generally “social biology” has appeared more appropriate. This way of linking the social and the biological exceeds the sole social medicine by involving also other medical disciplines. As such, forensics, whose an important activity is represented by clinical forensics in charge of types of violence (physical, psychological, sexual, abuse) and persons held in custody could see its practice heavily modified through the use of various data describing both the clinical situation of patients but also their context of life. A better understanding of mechanisms of violence development and potentially a better prevention of these situations allow forensics not to be restricted (or seen as limited to) a “descriptive medicine”, but to be seen also as a preventive and curative medicine. In this evolution, the potential contribution of Big Data appears significant insofar as information on a wide range of characteristics of the environment or context of life (social, economic, cultural) can be collected and be connected with health data, for example to develop models on social determinants of health. In the common thinking, the use of a larger amount of data and consequently a multiplicity of information via a multiplicity of databases would allow to access to a greater objectivity of a reality that we are approaching by fragmented viewpoints otherwise. In this light, the “bigger” and “more varied” would serve the “better” or at least the “more true”. But to be able to consider together or to link different databases it will be necessary to know how to handle this diversity regarding hypotheses made to build databases and regarding their purposes (by whom, for what bases have been made). It will be equally important to question the representativeness of situations that led to the creation of a database and to question the validity of information and data according to the secondary or tertiary uses anticipated from their original purpose. This step of data validity control for the anticipated use is a sine qua non condition, particularly in the field of public health, to guarantee a sufficient level of quality and exploit in the best way the benefits of Big Data approaches.

International audience; This work assesses the ability of equivalent-sphere models to reproduce the optical properties of soot aggregates relevant for lidar remote sensing, i.e. the backscattering and extinction cross sections. Lidar cross-sections are computed with a spectral discrete dipole approximation model over the visible-to-infrared (40 0-50 0 0 nm) spectrum and compared with equivalent-sphere approximations. It is shown that the equivalent-sphere approximation, applied to fractal aggregates, has a limited ability to calculate such cross-sections well. The approximation should thus be used with caution for the computation of broad-band lidar cross-sections, especially backscattering, at small and intermediate wavelengths (e.g. UV to visible).

International audience; Passive acoustic liners, used in aeronautic engine nacelles to reduce radiated fan noise, have a quarter-wavelength behavior, because of perforated sheets backed by honeycombs (with one or two degrees of freedom). However, their acoustic absorption ability is naturally limited to medium and high frequencies because of constraints in thickness. The low ratio “plate thickness/hole diameter” generates impedance levels dependent on the incident sound pressure level and the grazing mean flow (by a mechanism of nonlinear dissipation through vortex shedding), which penalises the optimal design of liners. The aim of this paper is to overcome this problem by a concept called LEONAR (“Long Elastic Open Neck Acoustic Resonator”), in which a perforated plate is coupled with tubes of variable lengths inserted in a limited volume of a back cavity. To do this, experimental and theoretical studies, using different types of liners (material nature, hole diameter, tube length, cavity thickness) are described in this paper. It is shown that the impedance can be precisely determined with an analytical approach based on parallel transfer matrices of tubes coupled to the cavity. Moreover, the introduction of tubes in a cavity of a conventional resonator generates a significant shift in the frequency range of absorption towards lower frequencies or allows a reduction of cavity thickness. The impedance is practically independent of sound pressure level because of a high ratio “tube length/tube hole diameter”. Finally, a test led in an aeroacoustic bench suggests that a grazing flow at a bulk Mach number of 0.3 has little impact on the impedance value. These first results allow considering these resonators with linear behavior as an alternative to classical resonators, in particular, as needed for future Ultra High Bypass Ratio engines with shorter and thinner nacelles.

International audience; This paper is dedicated to the characterisation of charging behaviour of space used polymers in space electron environment. Spacecrafts are indeed submitted in Medium Earth Orbit (MEO) to severe fluxes of electrons with energies ranging from a few keV to several MeV. For qualification of materials used on satellites and the pre-diction of their electrostatic behaviour in space environment, it is therefore important to tests these materials in representative environment. These experiments have been carried out at ONERA, The French Aerospace Lab (Toulouse, France) in the SIRENE facility. Different polymers (PEEK, ETFE, Kapton®, polyurethane and silicone varnish, polyurethane based paint) have been characterised to extract the main electric parameter that steer their charging behaviour in space environment: the radiation induced conductivity (RIC). These materials have then been tested in representative environment so as to study the evolution of their conductivity and charging behaviour as a function of the received radiation dose (for low and high dose levels). From these experiments, it was possible to extract the physical parameters that steer RIC and assess numerically their charging levels in specific MEO environment.

International audience; This paper aims at modelling opinion diffusion among agents with a logical approach by assuming that opinions are propositional formulas. In a first part, we present a model in which an agent changes its opinion by merging the opinions of some influential agents, its influencers. More precisely, it merges these opinions, which may be contradictory, by taking into account an order of importance among its influencers. In a second part, we generalize this model so that influencers are ordered according to several orders of influence which depend on the topics of opinions.; Dans cet article, on s'intéresse à la modélisation de la diffusion d'opinions dans un réseau solcial. L'approche préconisée est une approche logique qui consiste à modéliser les opinions comme des formules de la logique propositionnelle. On présente un modèle selon lequel les agents changent leur opinion en fusionnant les opinions de leurs influenceurs, selon l'importance de leur influence. Puis on généralise ce modèle en considérant que l'ordre d'importance des influenceurs dépend des thèmes abordés par les opinions.

International audience; The interaction phenomenon between High Power Microwave and cold plasma is governed by the Maxwell equations coupled with a fluid description of the plasma. We present in this paper a study of the operator A associated with the system of Maxwell/Plasma equations. As an application of this study, an existence and uniqueness result will be given under some assumptions on the matrices of permittivity, permeability, and on the parameters describing the plasma.

International audience; Reliability assessment in presence of epistemic uncertainty leads to consider the failure probability as a quantity depending on the state of knowledge about uncertain input parameters. The input joint distribution is often learnt from a small-sized dataset provided by operating experience. The computed failure probability depends on the estimated marginal distributions and the estimated copula distribution. This paper develops a reliability-oriented sensitivity analysis procedure in order to measure the influence exerted by the data-driven modeling of both the margins and the copula. The proposed methodology is validated for both deterministic and stochastic reliability methods through an extensive simulation study including several analytical performance functions as well as a real-life simulation code dealing with the buckling of a composite laminate plate.

International audience; The work presented in this paper focus on robot identification and presents a method based on the use of instrumental variables (IV). When dealing with en-bloc and offline identification of robots, the instrumental matrix constructed with the inverse dynamic model (IDM) and simulated data obtained from the simulation of the direct dynamic model (DDM). In this paper, a new recursive IV approach relevant for robot identification is presented. The instrumental matrix is constructed with the IDM and the references and their derivatives which are previously filtered by the transfer function of the position closed loop. This new way of building the instrumental matrix avoids the simulation of the DDM and offers some perspectives for online identification and real-time implementation. This recursive IV method termed IDIM-RIV (Inverse Dynamic Identification Model Recursive Instrumental Variables) is experimentally validated on the two degrees-of-freedom SCARA robot. Finally, some hints for real-time implementation are provided.

International audience; Flood management is particularly important for many urban territories. In order to assess the interest of different risk mitigation strategies, it is necessar y to consider the human behavior. Different models and approaches are available to model and simulate people behaviors during a flood event. Despite the considerable recent progress of these models, none of them succeeds in answering a l l the required challenges: (1) simulate the flood event, (2) integrate geographical information, (3) take into account complex behaviors for inhabitants considering emotion and partial knowledge, (4) enable different strategies for inhabitants, (5) take into account the degradation of infrastructures and its impact on their functioning, and (6) ensure the genericity and flexibility of the model in order to be able to apply it to any territory. In order to meet these challenges, we provide a new Agent based Model, called SiFlo. In this paper, we present this model and an application to La Ciotat.

International audience; Following the reentry of the Intermediate eXperimental Vehicle in 2015, a lot of efforts were carried out at the ONERA for the post-flight analysis and the reconstruction of the heat flux applied to the vehicle. This flight represents a unique means of validation of the computational tools employed for the design of such mission. The aim of this paper is to exploit for the first time these data in the rarefied portion of the vehicle’s reentry. In this context, DSMC simulations were performed between 115 and 90 km and a CFD computation was made for the 90 km flight point. In the standard numerical conditions, different degrees of agreement are obtained and a sensitivity analysis to various numerical and atmospheric parameters provides several ways to significantly improve the results. In addition, the DSMC and CFD comparison provides a good agreement for the surface quantities and suggestions to reach a better level of consistency between both methods and the flight data are finally discussed.

International audience; The aircraft scheduling problem consists in sequencing aircraft on airport runways and in scheduling their times of operations taking into consideration several operational constraints. It is known to be an NP-hard problem, an ongoing challenge for both researchers and air traffic controllers.The aim of this paper is to present a focused review on the most relevant techniques in the recent literature (since 2010) on the aircraft runway scheduling problem, including exact approaches such as mixed-integer programming and dynamic programming, metaheuristics, and novel approaches based on reinforcement learning. Since the benchmark instances used in the literature are easily solved by high-performance computers and current versions of solvers, we propose a new data set with challenging realistic problems constructed from real-world air traffic.

International audience; We prove that any implementation of pivotal sampling is more efficient than multinomial sampling. This yields the weak consistency of the Horvitz Thompson estimator and the existence of a conservative variance estimator. A small simulation study supports our findings.

International audience; The atmospheric cosmic-ray environment is composed of secondary particles produced when primary cosmic rays interact with the nucleus of atmospheric atoms. Modeling of atmospheric radiations is essential for investigating their impacts on human activities such as radiation risks in aviation or scientific fields such as cosmogenic dating. The nuclear transport codes are a common and accurate way to model the cosmic ray interaction in the atmosphere with minimal approximations. However, tracking all produced secondary particles in each event in the whole depth of the atmosphere and sampling many events to obtain the statistically meaningful results would be a computational challenge and disadvantageous from the point of view of time consumption. This paper presents a computational platform names ATMOS CORE based on pre-calculated databases coupled to physical models and computational methods. The fields of application concern the atmospheric cosmic-rays characterization as well as their effects on electronics systems, on the ambient dose for aircrews or the cosmogenic nuclide production for dating activities. Some comparisons between simulations and measurements are also presented and discussed.

International audience; Ceilometers are widely spread instruments mainly used for cloud base height determination. However, recent models are more sensitive to aerosols; hence, nowadays there is an increasing interest in these instruments to retrieve aerosol optical and microphysical properties.The high number of them distributed around the globe compared to the robust lidar systems and the fact that ceilometers work under unattended conditions are the main reasons behind this interest. In this paper a new methodology is proposed to retrieve aerosol vertical extinction and backscatter profiles from a Vaisala ceilometer CL51. This methodology is based in two parts: first, a signal pre-processing with a suppression of the dark current and background noises, and a correction of the water vapor absorption using near-real time temperature and absolute humidity (AH) profiles from a co-located Microwave radiometer (MWR). Then an iterative Klett-based algorithm that uses AERONET (AErosol RObotic NETwork) AOD (Aerosol Optical Depth) as an input to retrieve the extinction and backscatter profiles. The error analysis of the aerosol retrievals has been performed between MWR measurements and modelled radiosondes from HYSPLIT. The absolute errors found in temperature and AH are leading to errors in the pre-processed RCS signals up to 9%, and then in particle backscatter and particle extinction coefficients up to 2:2% and 25%, respectively.; Les ceilomètres sont des instruments très répandus, principalement utilisés pour déterminer la hauteur de la base des nuages. Cependant, des modèles récents sont plus sensibles aux aérosols ; c'est pourquoi, de nos jours, on s'intéresse de plus en plus à ces instruments pour mesurer des données optiques des aérosols et leurs propriétés microphysiques. Le nombre élevé de ces derniers, répartis dans le monde entier, par rapport aux systèmes lidar robustes et le fait que les plafonds fonctionnent dans des conditions non surveillées sont les principales raisons de cet intérêt. Dans ce document, une nouvelle méthodologie est proposée pour déterminer par inversion les profils d'extinction verticale et de rétrodiffusion des aérosols à partir d'un modèle CL51 de ceilomètre de Vaisala. Cette méthodologie est basée sur deux parties : premièrement, un prétraitement du signal avec une suppression du courant d'obscurité et du fond et une correction de l'absorption de la vapeur d'eau en utilisant des profils de température et d'humidité absolue (AH) en temps quasi réel d'un radiomètre à micro-ondes (MWR) colocalisé. Ensuite, un algorithme itératif basé sur Klett qui utilise AERONET (AErosol RObotic NETwork) AOD (Aerosol Optical Depth) comme entrée est appliquée pour récupérer les profils d'extinction et de rétrodiffusion. Les erreurs absolues trouvées dans la température et l'AH entraînent des erreurs dans les signaux RCS prétraités jusqu'à 9 %, puis dans les coefficients de rétrodiffusion et d'extinction des particules jusqu'à 2,2 % et 25 %, respectivement.

International audience; Taking into account radiation effects is a crucial part of the design and optimization of applications involving high temperatures. This paper outlines the development of a predictive coupling model for steady state conjugate heat transfer problems including radiative boundary conditions that models radiative exchanges between gray walls in a transparent medium. This canonical model is based on the Godunov–Ryabenkii normal mode analysis theory. The general expression of the amplification factor, the stability bounds and the optimal coefficients are provided. Moreover, a numerical Biot number including radiation effects that controls the stability of the model, is proposed. The destabilizing effect of radiation is highlighted and quantified. A specific test case is then presented to evaluate the consistency of this model. The numerical and physical parameters of this test case were specifically designed to target large fluid-structure interactions (ceramic material, high radiative coefficient). The numerical results fully comply with the theoretical results derived from the predictive model.

International audience; Many two-phase flows relevant to natural and industrial applications are characterized by high density ratios and high shears at the interface. These peculiarities make numerical simulations of such kind of flows still challenging. In particular, incompressible Level-Set/Volume-of-Fluid-based solvers are affected by the onset of diverging spurious velocities close to the interface. In this paper a new strategy, able to overcome these numerical instabilities, is described for staggered Cartesian grids. In order to achieve a consistent mass-momentum advection, a new auxiliary continuity equation is introduced and resolved along the momentum equations in the velocity control volumes. The mass fluxes are evaluated through the Volume-of-Fluid color function and directly used to calculate the momentum convective term. Several high-density test cases (the density ratio going from 10 3 to 10 6) are presented: the new algorithm shows significant improvements in stability and accuracy over the standard velocity based advection methods, together with a very low increase in computational time, estimated at 5% ÷ 10%. Therefore, it is suitable to simulate more complex and realistic high density ratio two-phase flows, such as the breakup of a liquid jet in cross-flow here described.

International audience; Electromechanical resonant de-icing systems provide a low-energy solution against ice accumulation on aircraft. Recent researches show a growing interest towards these systems in the context of more electrical aircraft. Electrome-chanical de-icing systems consists in electric actuators producing stress within the ice, through micro-vibrations of the surface to be protected, leading to bulk or adhesive failure and, ultimately, ice shedding. The understanding of the mechanisms at play is of prime importance in order to design efficient ice protection systems. Despite a large number of studies in the literature, there is still a lack when dealing with fracture propagation phenomena in this context. In this work the authors propose a model based on the well established phase-field variational approach to fracture. The approach is applied to the study of crack propagation and debonding of ice under the effect of an electromechanical resonant de-icing system. Numerical experiments are performed in order to assess possible ice shedding mechanisms.

The modeling of radiative properties of soot particles can be addressed by a number of methods. Among them, the canonical Rayleigh-Debye-Gans (RDG) theory and the Superposition T-Matrix Method (STMM) are particularly well adapted to the task. Here, both RDG and STMM are used to model the radiative properties of two types of fractal aggregates indicative of soot relevant to lidar sensing. One type, a canonical aggregate with a chain-like morphology, corresponds to low-sooting flames and is well characterized by a single fractal dimension. The other type, a superaggregate, exhibits multiple fractal dimensions and is seen in heavily sooting flames. Radiative properties such as the differential scattering cross-section, total scattering cross-sections, backscattering cross-sections, and linear depolarization-ratio (LDR) are calculated for a range of wavelengths from 300 − 1100 nm while including the wavelength dependence of the soot refractive index. Of particular interest is that depolarization by a superaggregate is found to be approximately ten times larger than the depolarization by a canonical chain-like aggregate and both exhibit a power-law with wavelength. Results for specific wavelengths of interest to lidar (355, 532, and 1064 nm) are tabulated for lidar applications. Additionally, RDG theory yields fairly accurate results for modeling the radiative properties, including lidar relevant parameters such as backscattering cross-sections, only for canonical soot fractal aggregates.

International audience; Soot formation has become an important issue in the design of gas turbine combustors due to its environmental impact and its contribution to radiative heat transfer in the combustion chamber. However, efficient and accurate prediction of soot particles formation, growth, oxidation and interaction in gas turbine combustors is still an open field in computational fluid dynamics. The present approach proposes to combine a reduced gas-phase chemistry, a sectional model for polycyclic aromatic hydrocarbons, and a Lagrangian description of soot particles dynamics. The Lagrangian description has been chosen for its ability to simulate the evolution of the particle size distribution. A numerical procedure is proposed to minimise its CPU cost. This approach was successfully applied to the simulation of steady laminar premixed ethylene-air flames at three fuel equivalence ratios, which constitutes a prerequisite towards its use in an aeronautical combustion chamber.; La formation de particules de suie constitue un enjeu du design des moteurs aéronautiques, du fait des contraintes environnementales croissantes dans l'industrie des transports et de la contribution importante des suies au rayonnement dans les chambres de combustion. Toutefois, en CFD, il n'existe actuellement aucune méthode à la fois précise et efficace pour la prédiction de la formation, de la croissance et de l'oxydation des particules de suie. Ainsi, l'approche présentée ici propose de décrire la chimie en phase gazeuse par un mécanisme réactionnel réduit combiné à un modèle sectionnel pour les hydrocarbures aromatiques polycycliques (PAH), et d'y coupler une description Lagrangienne de la dynamique des particules de suie. La description Lagrangienne est en effet très utile pour simuler l'évolution de la distribution en taille des particules. Une méthode numérique de réduction de population permet également ici de réduire le coût CPU du solveur Lagrangien. L'approche a été appliquée avec succès à la simulation de flammes laminaires stationnaires de prémélange à trois richesses différentes, ce qui constitue une première étape vers l'application à un foyer aéronautique.

International audience; A laboratory experiment is set up to study both surface and in-depth soil moisture content (SMC). For that purpose, an aquarium is filled successively with two soils, a clay loam and a sand. Reflectance spectra are acquired in the solar domain (400–2400 nm) on the soil surface using an ASD FieldSpec 3 HR spectroradiometer and in-depth through the aquarium glass wall using two hyperspectral cameras. Successive amounts of water ranging from low to heavy rainfall in a temperate region are uniformly poured into the aquarium. The MARMITforSMC method based on the MARMIT (MultilAyer Radiative Transfer Model for soIl reflecTance) model is applied to each reflectance spectrum to determine gravimetric SMC. In particular, vertical profiles of SMC are provided with unprecedented spatial accuracy (~0.287 mm). The results are compared with volumetric SMC measured by two time-domain reflectometry (TDR) sensors. The in-depth SMC image produced on the sand shows lower values within the first 2 cm (5%) than below (17%). In contrast, the SMC image produced on the clay loam shows evenly distributed values whatever the position in the aquarium, even 1 h after moistening. The difference in grain size between the soils explains this result.; Une expérience est montée en laboratoire pour étudier l’humidité (SMC) du sol à la fois en surface et en profondeur. Pour cela, un aquarium est successivement rempli avec deux sols, un limon argileux et un sable. Les spectres en réflectance sont acquis dans le domaine solaire (400-2400 nm) en utilisant un spectroradiomètre ASD FieldSpec 3 HR pour la surface et deux caméras hyperspectrales pour le profil derrière la paroi de l’aquarium. Des quantités successives d’eau, allant de la pluie faible à forte pour une région tempérée, sont versées uniformément dans l’aquarium. La méthode MARMITforSMC s’appuyant sur le modèle MARMIT (Modèle de Transfert Radiatif Multicouches pour la réflectance du sol) est appliquée à chaque spectre en réflectance pour déterminer l’humidité gravimétrique correspondante. Ceci permet en particulier d’obtenir des profils verticaux d’humidité avec une résolution spatiale sans précédent (0 ,287 mm). Les résultats sont comparés aux mesures d’humidité volumétrique obtenues à l’aide de sonde de réflectométrie dans le domaine temporel (TDR). Les cartes de profil d’humidité générées pour le sable montrent des valeurs plus faibles pour les 2 premiers centimètres (5 %) qu’au-delà (17 %). Par contre, les cartes de profil d’humidité générées pour le limon argileux montrent des valeurs homogènes quelle que soit la profondeur, même 1 heure après l’humidification. La différence de granulométrie des sols explique ces résultats.

The Chronic Kidney Disease (CKD) Prognosis Consortium is a collaborative author of the above-mentioned article. The CKD Prognosis Consortium investigators/collaborators are as follows: • African American Study of Kidney Disease and Hypertension (AASK): Brad Astor, Lawrence J. Appel; Canadian Study of Prediction of Death, Dialysis and Interim Cardiovascular Events (CanPREDDICT): Adeera Levin, Mila Tang, Ognjenka Djurdjev; Cleveland Clinic CKD Registry Study (CCF): Sankar D. Navaneethan, Stacey E. Jolly, Jesse D. Schold, Joseph V. Nally Jr.; Chronic Renal Impairment in Birmingham (CRIB): David C. Wheeler, Jonathan Emberson, John Townend, Martin Landray; Chronic Renal Insufficiency Cohort Study (CRIC): Harold I. Feldman, Chi-yuan Hsu, James P. Lash, Lawrence J. Appel; Chronic Renal Insufficiency Standards Implementation Study (CRISIS): Philip A. Kalra, James P. Ritchie, Raman Maharajan, Rachel J. Middleton, Donal J. O'Donoghue; German Chronic Kidney Disease Study (GCKD): Kai-Uwe Eckardt, Markus P. Schneider, Anna Kottgen, Florian Kronenberg, Barbara Barthlein; Geisinger Health System: Alex R. Chang, Jamie A. Green, H. Lester Kirchner, Kevin Ho; Grampian Laboratory Outcomes, Morbidity and Mortality Studies – 2 (GLOMMS2): Angharad Marks, Corri Black, Gordon J. Prescott, Nick Fluck; Gonryo Study: Masaaki Nakayama, Mariko Miyazaki, Tae Yamamoto, Gen Yamada; Hong Kong CKD Studies: Angela Yee-Moon Wang, Sharon Cheung, Sharon Wong, Jessie Chu, Henry Wu; Ontario Institute for Clinical Evaluative Sciences, Provincial Kidney, Dialysis and Transplantation program (ICES KDT): Amit X. Garg, Eric McArthur, Danielle M. Nash; Maccabi Health System: Varda Shalev, Gabriel Chodick; Multifactorial Approach and Superior Treatment Efficacy in Renal Patients with the Aid of a Nurse Practitioner (MASTERPLAN): Peter J. Blankestijn, Jack F.M. Wetzels, Arjan D. van Zuilen, Jan A. van den Brand; Modification of Diet in Renal Disease Study (MDRD): Andrew S. Levey, Lesley A. Inker, Mark J. Sarnak, Hocine Tighiouart; Nanjing CKD Network Cohort Study (Nanjing CKD): Haitao Zhang; NephroTest Study (NephroTest): Benedicte Stengel, Marie Metzger, Martin Flamant, Pascal Houillier, Jean-Philippe Haymann; National Renal Healthcare Program – Uruguay (NRHP-URU): Pablo G. Rios, Nelson Mazzuchi, Liliana Gadola, Veronica Lamadrid, Laura Sola; New Zealand Diabetes Cohort Study (NZDCS): John F. Collins, C. Raina Elley, Timothy Kenealy; Parcours de Soins des Personnes Agees (PSPA): Olivier Moranne, Cecile Couchoud, Cecile Vigneau; Primary-Secondary Care Partnership to Prevent Adverse Outcomes in Chronic Kidney Disease (PSP CKD): Nigel J. Brunskill, Rupert W. Major, David Shepherd, James F. Medcalf; Racial and Cardiovascular Risk Anomalies in CKD Cohort (RCAV): Csaba P. Kovesdy, Kamyar Kalantar-Zadeh, Miklos Z. Molnar, Keiichi Sumida, Praveen K. Potukuchi; Reduction of Endpoints in Non-insulin Dependent Diabetes Mellitus with the Angiotensin II Antagonist Losartan (RENAAL): Hiddo J.L. Heerspink, Dick de Zeeuw, Barry Brenner; Stockholm CREAtinine Measurements Cohort (SCREAM): Juan Jesus Carrero, Alessandro Gasparini, Abdul Rashid Qureshi, Carl-Gustaf Elinder; Second Manifestations of ARTerial Disease Study (SMART): Frank L.J. Visseren, Yolanda van der Graaf; Swedish Renal Registry CKD Cohort (SRR CKD): Marie Evans, Maria Stendahl, Staffan Schon, Marten Segelmark, Karl-Goran Prutz; Sunnybrook Cohort: David M. Naimark, Navdeep Tangri; West of Scotland CKD Study: Patrick B. Mark, Jamie P. Traynor, Colin C. Geddes, Peter C. Thomson.• CKD Prognosis Consortium Steering Committee: Alex R. Chang, Josef Coresh (Chair), Ron T. Gansevoort, Morgan E. Grams, Anna Kottgen, Andrew S. Levey, Kunihiro Matsushita, Mark Woodward, Luxia Zhang.• CKD Prognosis Consortium Data Coordinating Center: Shoshana H. Ballew (Assistant Project Director), Jingsha Chen (Programmer), Josef Coresh (Principal Investigator), Morgan E. Grams (Director of Nephrology Initiatives), Lucia Kwak (Programmer), Kunihiro Matsushita (Director), Yingying Sang (Lead Programmer), Aditya Surapaneni (Programmer), Mark Woodward (Senior Statistician).• Kidney Disease Improving Global Outcomes (KDIGO) Controversies Conference on Prognosis and Optimal Management of Patients with Advanced CKD: Kai-Uwe Eckardt (Conference Co-Chair), Brenda R. Hemmelgarn (Conference Co-Chair), David C. Wheeler (KDIGO Co-Chair), Wolfgang C. Winkelmayer (KDIGO Co-Chair), John Davis (CEO), Danielle Green (Managing Director), Michael Cheung (Chief Scientific Officer), Tanya Green (Communications Director), Melissa McMahan (Programs Director).

International audience; Because of the geomagnetic field shape, the polar regions are the most exposed to secondary particles and radiation produced by primary cosmic rays in the atmosphere. At present, only few experimental measurements of environmental dose are reported in literature at high southern latitudes. A three year campaign has been carried out in two different locations, Ushuaia (Argentina, 54.80∘ S, 68.30∘ W) and Marambio (Antarctica, 64.24∘ S, 56.63∘ W), using a Liulin type detector, allowing to measure the total environmental radiation flux and dose. The Liulin type instrument, measuring the energy deposition in a silicon detector, is especially suitable to evaluate the dose, separating the low and high LET (Linear Energy Transfer) components. The instrument was installed at the GAW Station in Ushuaia and inside the LAMBI Laboratory at the Marambio Antarctic base. In December 2017 preliminary measurements have been carried out at the French-Italian base Dome C, at 3233 m a.s.l., with a Liulin-AR, a new version of Liulin spectrometer, specifically built for this application by the Space Research and Technology Institute of Bulgarian Academy of Sciences. In this paper the environmental dose values obtained in the different southern high latitude locations are compared and discussed.