Approche bayesienne pour gérer les incertitudes dans l'identification à partir de mesures de champ

La méthode d'identification bayesienne présente l'avantage de pouvoir tenir compte de différentes sources d'incertitude présentes dans le problème et de quantifier l'incertitude avec laquelle les propriétés sont identifiées aussi bien en termes de variances que de corrélations. Son application à un problème d'identification de propriétés élastiques orthotropes à partir de mesures de champs de déplacements par Moiré interférométrique est présentée dans ce papier

Groundwater, geothermal modelling and monitoring at city-scale : reviewing European practice and knowledge exchange : TU1206 COST sub-urban WG2 report

The need for cities to make more effective use of the subsurface on which they stand, is increasingly being recognised in Europe and further afield to be essential for future cities to be sustainable and more resilient [1,2]. However, city planning worldwide remains largely 2D, with very few cities having any substantial subsurface planning or Masterplans – the cities of Helsinki, Montreal, Singapore being rare exceptions [3,4]. The consequences of inadequate consideration and planning of the subsurface are far-reaching, in economic, environmental and social terms. Across Europe, poor understanding of ground conditions is recognised as the largest single cause of construction project delay and overspends [5]. Management of urban groundwater and shallow geothermal energy resources is becoming increasingly important as cities are increasingly looking to use these resources to meet current and future energy and heating and water needs. Whilst these are, alongside potential underground building space, the two most important resources for future cities, the monitoring and regulation of these resource is widely variable across Europe. For subsurface opportunities such as groundwater and geothermal energy to be realised and utilised to greatest effect to support growing city populations and infrastructure, city planners must be both aware of, and have some understanding of the resources, available data and research, and both the opportunities and risks which the resources provide to city development [6,7]. To supply this understanding to city municipalities and others, geological surveys must have robust datasets of groundwater and geothermal resources at city-scale, and the relevant knowledge and understanding from these data must be made accessible to inform subsurface planning in appropriate datasets relevant to different scale of interest in different planning stages. What density and frequency of data are required for a robust understanding of a city’s groundwater and geothermal resources will be different in different cities, according to the complexity of the resources, and the intensity of subsurface use and demands on the resources. Indeed, no one design of city-scale monitoring or modelling of ground-water and -heat resources is appropriate for all cities, or for all monitoring objectives. However, the guiding principles of good practice for developing robust city-scale monitoring, and datasets are widely applicable, as are the key principles for ensuring these data inform city planning processes. This report provides an initial review of existing examples of current practices in Europe with respect to groundwater and geothermal monitoring and modelling, as a resource for other cities to learn from and build upon. The report also provides an overview of some of the different practices used for communicating groundwater and geothermal energy data and knowledge to inform urban planning and managemen

Pylon and engine mounts performance driven structural topology optimization

International audienceEngine deformations during operation are an increasing concern for engine performances. The tip-clearance, defined as the radial gap between the blade tip and the engine casing, can show small variations induced by aircraft maneuvers. These variations can produce increased tip leakage flow, secondary flows and vortex losses that can sensibly increase the engine trust specific fuel consumption (TSFC). In this paper the impact of pylon and nacelle design parameters on in-operation engine performance and overall mass is investigated for a turbofan engine. The structural behavior of the integrated engine will be simulated thanks to a linear finite element model that models the mechanical behavior of the engine under different load cases. Both rotor and stator are modelled to evaluate tip clearance deformations at different engine stages. In a first order approach these engine deformations are evaluated as the difference of radial displacements of superposed points of rotor and stator relative to blade tip. Then an in house performance engine model evaluates thrust specific consumption as a function of the tip clearances. In this paper, two structural optimization studies are conducted on a simple generic engine model in order investigate two different approaches to optimize the engine-pylon attachment. In the first study a classic statically determined engine mount system is considered and thrust link position and attachment points are made varying. In the second one, a topology optimization framework is developed and implemented to optimize from scratch the topology of the pylon-engine attachment design zone

Original pylon architecture design using 3D HPC topology optimization

International audienceIn the context of fuel consumption reduction, integrated power-plant system optimization plays a central role in the definition of on-wing engine performance. The fuel consumption is affected, among other, by specific engine deformations, called tip clearances. This study con- cerns the optimization of the engine-pylon attachment structure with respect to the tip clear- ances (and thus the fuel consumption). A hyper-static concept for engine to aircraft attach- ment structure is considered for the design zone and optimized within a topology optimization framework. A simple engine model is integrated to a 3D design zone model through static con- densation. Stress based constraints as well as the fuel consumption based objective function are implemented within the proposed topology optimization framework. In order to achieve realistic designs, high density for the mesh of the design zone is needed. Accordingly a parallel implementation within an HPC framework was considered. First results in this direction are presented

Aquifer Vulnerability and Contamination Risk

Water supply systems must be designed in such a way to ensure groundwater extraction sustainability. In addition, the quality of pumped water must also be guaranteed, and this entails protecting the groundwater source from contamination. To do so, it is necessary to identify the physical and hydraulic characteristics of the soil, the unsaturated medium and the aquifer itself that influence the migration of contaminants spilled at the surface towards the aquifer, and hence potentially towards sensitive targets (i.e., drinking water pumping wells). The susceptibility of an aquifer to become polluted following a contaminant spill is called vulnerability, and its assessment is the focus of this chapter. Of the four categories of vulnerability assessment methods, i.e., overlay, index and statistical methods, and process-based simulation models, this chapter presents examples of the former two, which are of easier implementation and are widely used. Overlay methods define aquifer vulnerability on the basis of groundwater circulation and rely on the superposition of maps of the hydrogeologic, structural and morphologic setting. Index methods, instead, are based on the assignment of scores (sometimes weighed) to sets of parameters that are likely to affect the degree of vulnerability. Specific methods of these two categories described in detail in this chapter are the one developed by the Bureau de Recherches Géologiques et Minières in France, the Italian CNR-GNDCI and SINTACS methods, the US-EPA DRASTIC method and the British GOD method. The suitability of different methods is discussed, and how vulnerability assessment can be used to determine the risk of contamination is presented. On this basis, an example of contamination risk reduction strategies is illustrated