Any device and system currently manufactured in the world needs to comply with EMC (electromagnetic compatibility) standards aimed at ensuring a correct performance in an inevitably electromagnetically polluted environments. One of the most important is the case of radiated tests, where external EM (electromagnetic) waves impinging on the SUT (system under test): in practice, it is of interest for a laptop exposed to a nearby mobile phone or an airplane landing in proximity of a radar station. The level of immunity of an SUT is typically assessed in facilities where one or more impinging waves are generated and the subsequent impact on the SUT is assessed. Any type of test currently used is based on a one-to-one interpretation, where each test configuration (e.g., direction of arrival of the wave) gives rise to a measurable effect. Although delivering a simple interpretation of the results, this approach has strong limitations: practical constraints (time, costs) impose a maximum number of test configurations that cannot in any way be regarded as exhaustive of all possible threats; single test configurations are separately defined and the corresponding results are analyzed just looking for the worst-case among the few configurations tested. A more effective and robust approach would rather consist in devising a finite number of tests in such a way as to explore the general behavior of the SUT, to any kind of external interferer. In other words, it is possible, as done in many other fields, to apply a learning approach, where the outcome is a better understanding of the SUT behavior. The availability of a behavioral model of the SUT will allow predicting its behavior to any external threat, without requiring further tests. Two direct results are therefore possible: 1) to reduce the number of tests, thus speeding up the time spent in a test facility (cost reduction); 2) the certainty of knowing beforehand what could be the worst-case configurations for an external interferer (risk management, accuracy). Current test approaches are incapable of delivering these advantages, since the tests are intended to probe single responses to single interferer scenarios rather than a global behavior. This project aims at defining the tools needed for this change of paradigm, by exploiting the remarkable properties of the TREC (time-reversal electromagnetic chamber), a new test facility recently developed in Supelec. The TREC has been demonstrated to allow a flexible generation of wavefronts, under real-time conditions, without recurring to expensive arrays of sources, but rather taking advantage of diffusive media. Any combination of the parameters of the interferer can be generated, even multipath scenarios, by means of signal-processing techniques. This project will allow extracting a macromodel of the SUT, relating a parametric description of any interferer scenario, to the inner state variables of the SUT: this can be represented as a generalized transfer function of the system, though it will also be able of reproducing the likely non-linear behavior of the SUT electronics. The main tools used for this feature will come from statistical inference, widely used in many diverse fields involving complex interactions, ranging from sociology to data-mining. In practice, the proposed approach will allow a direct identification of the position and nature of coupling paths (e.g., faults in the SUT shielding), a precious tool in R&D phases. Moreover, the non-linear macromodelling of the SUT behavior will provide direct information about the most critical interferer scenario that could put an SUT in fault: this is of interest for industrial as well as defense issues, e.g., in aeronautics and electronic warfare. The result of this project will be the definition of a new research field, EMC imaging, which will pave the way to the integration to EMC testing of advanced signal-processing techniques, already successfully applied in fields such as radar imaging.

This project falls within the framework of aviation security related to icing. Recent serious events related to icing with the presence of droplets with diameter between 50 microns and 1 millimetre lead to the modification of the regulation for aircraft certification. In order to deal with these new demands in terms of certification, we saw the emergence of European projects such as WEZARD or EXTICE in which new wind tunnel capabilities where developed in icing conditions. However, even if those capabilities are now fully operational, it is not certain that the reproduced icing conditions are fully controlled until specific parameters such as the supercooled droplets temperature or local hygrometry are checked and measured. Furthermore, it is necessary to check that the droplets are really over icing and to evaluate the presence of ice in the droplets. To date and to our knowledge, there is no reference experiment to deal with those three parameters. Thus, this project aims to develop, from existing techniques, new experimental diagnostics to measure supercooled droplets temperature, the fraction of ice within the droplet and the hydrometry with the presence of droplets, in icing aeronautical conditions. These conditions involve droplets having velocities up to about 250 m/s and diameter of several millimetres. Therefore, this ambitious project will be carry out via a partnership gathering together four labs (LEMTA from the Université de Lorraine, DGA Essais Propulseurs in Saclay, IRSTEA in Antony and CORIA in Rouen), each lab bringing its own expertise. Taking into account that icing aeronautical conditions are an extreme environment, this project is split in two work-packages. The first work-package is dedicated to the development of all the measurements techniques leading to characterize supercooled droplets having velocity and diameter of about 10 m/s and 300 µm respectively. The second work-package constitutes the main output of the project since the goal is to apply the previous improved measurements techniques under aeronautical conditions (velocity of about 150 m/s in maximum). In parallel, a transverse numerical activity will be undertaken in order to bring assistance for several expected steps in both work-packages. The first work-package is divided in three parts. The first one is devoted to the development of an experimental set-up (Experiment 1) to allow the generation of supercooled droplets at lower velocity (about10 m/s). For the second part, the experimental techniques for the measure of the droplet temperature, the fraction of ice within the droplet and the hygrometry will be set-up. The second work-package will be conducted also in two parts. In a first part, a small size dynamic wind tunnel will be developed (Experiment 2) to generate supercooled droplets at high speeds. Then, Experiment 2 will be used to undertake an experimental campaign in order to characterise the over melted droplets (temperature and ice fraction). On top of this, the project is also intending to provide a sufficient level of maturity for measurement techniques which could be used on one side for the normalisation work of the Society of Automotive Engineers (SAE) (Calibration methods for icing plants) and on the other side for a potential involvement in future European projects to complement EXTICE.

The new 2013/35 EU Directive, defining minimum health and safety requirements regarding the exposure of workers to electromagnetics fields, shall be transposed in member states regulations by July 2016. These exposure limits for workers are expressed in terms of internal electric field and Specific Absorption Rate (SAR). Similar exposure limits (head and trunk current densities and SAR) have already been applied in the French Ministry of Defence since 2003. Indeed, soldiers also evolve next to high power emitters which can radiate fields above accepted reference levels over large areas. A trade-off between jamming efficiency or communication distance (in HF, VHF or UHF) and conformity with respect to regulation on personnel exposure is therefore sought. As it is difficult to measure the EM quantities inside the human body, the demonstration of conformity versus regulation usually relies on numerical simulation (dosimetry) taking into account complex human models as well as surrounding emitters and structures. These numerical tools solving Maxwell’s equations must be adapted in order to meet the new challenges brought by civil and military regulations (exposure limits expressed in terms of SAR, current densities or internal electric fields). Tools able to handle such complex models rely on few numerical methods: the Finite Element Method (FEM), the Finite Difference Time Domain (FDTD) method, the resolution of integral equations with the Method of Moment (MoM), the Transmission-Line Matrix (TLM) method, and the recent Galerkin Discontinuous Time Domain (GDTD) method. Each of these can be the most suitable method to use depending on the case. For numerical dosimetry, volumic methods are preferred as human models are usually described in terms of volumic pixels (voxels) with similar size as the computation cell. If transients are to be included, then both FDTD and TLM prevail. The first one is the more popular because of its simple algorithm, and has been implemented into several commercial tools. Although published a decade later, TLM has not been as widely used. It is however proved to be less dispersive, more physical because of its analogy with circuit models, and inherently stable while using the maximum allowed time step for stability. Moreover, recent works showed that TLM provides faster convergence and is more accurate than FDTD (or FIT) for structures with highly contrasted constitutive parameters such as voxel human heterogeneous models. However, only one commercial tool (developed by a foreign company) is currently based on TLM, with little past and foreseen evolution, as FDTD prevails among electromagnetic simulation users. The objective of the present project is to elaborate the bricks of a versatile TLM simulator oriented towards military and civil dosimetry needs with extensions such as thermal coupling (strong hybridization) not available in commercial tools. It will rely on the recognized competence of 2 French laboratories working on TLM along with the competence of DGA Aeronautical Systems for Defence applications, and will be based on existing modules developed in these laboratories. Thermal effects of electromagnetic waves will also be studied through a novel TLM thermal model. Significant outcome is foreseen. First, the competence of the French TLM community will be sustained and reinforced. Second, the project will deliver a novel TLM simulator with open computation core and massively paralleled features, of significant use for Defence and for industrial applications. Finally, the structure of this demonstrator will enable constant evolution and diffusion towards telecommunications, biomedical applications, as well as RF drying (wood, vegetables, …) and RF cooking.

The project falls within the framework of hazardous related to icing, a natural phenomenon that affects many sectors of activity such as transportation (land, air and sea) but also energy (distribution and production). Icing is characterized by the accretion of ice on cold walls which alters the performance of the system and, as a result, can lead to major incidents (fall of high-voltage lines or wind turbine blades) or even dramatic incidents (aircraft crashes). The present project has identified the aviation sector as the main field of application. Indeed, there are of course Icing Protection Systems (IPS) but their deployment is limited to a few aircraft. There are many reasons for this, but they mainly concern energy consumption and/or excessive space requirements, as well as a lack of reliability. Consequently, the objective of the project is to develop a new thermal protection system against icing based on a Dielectric Barrier Discharge (DBD) as a plasma actuator. The actuator consists of establishing a plasma on the surface of a dielectric through two electrodes arranged on either side of the dielectric. The strategy of the project is based on the improvement of the electrothermal conversion of the actuator where part of the electrical energy heat the dielectric surface and also the surrounding gas. Two approaches are considered to improve the heat conversion: development of new materials composing the dielectric and development of new configurations of the actuator (method of realization and geometry of the electrodes). In addition, the use of more strength materials (ceramics) will also improve the sustainability of the new system in the face of an aggressive environment such as icing aeronautical conditions (air temperature at -40°C and velocity of impinging droplets of the order of 100 m/s). To carry out this project, a consortium of four partners has been established (the PPRIME institutes of the University of Poitiers and IJL of the University of Lorraine, the LEMTA laboratory of the University of Lorraine and the DGA Propulsion Test Center in Saclay). The project is divided into four tasks. The first three tasks constitute a first phase of the project, mainly fundamental, focused to the development of new configurations of plasma actuators but also to the improvement of the knowledge of the mechanisms governing the electrothermal conversion. The ability of these new configurations to de-ice a wall (i.e. to remove ice previously deposited) or to anti-ice (i.e. prevent ice deposition) will be evaluated without airflow but in a cold environment (-40°C) and with supercooled droplets (velocity of about 10 m/s and diameter of about 300 µm). The second phase, more applicative, consists in testing and validating one or several new systems designed in the first phase in an icing wind tunnel allowing reproducing aeronautical conditions (air temperature of -40°C, airflow velocity of about 100 m/s and droplet diameters around 20 and 300 µm). Finally, the project also aims to contribute to the European Eurodrone program by proposing a new thermal icing protection technology for the future European UAV.

Predicting the behavior of fire in confined enclosures with and without mitigation using water-based firefighting systems is a topic of great interest for both civil and military fields. Although notable advances have been made in this area from prescriptive or analytic approaches, these conventional approaches fail in reproducing fire behavior in polydisperse amorphous massively multi-compartmented structures (e.g. naval vessels, high-rise buildings, warehouses, or nuclear plants). The reasons are manifold: the lower relevance of the physical models used the difficulty in accounting for the role of some influential factors on fire behavior, and/or the requirement of prohibitive amounts of memory and computational resources. The present project aims at modeling and achieving super-real time simulations (faster than real time) of fire propagation and its limitation using water systems in such complex structures. The approach we propose to describe large-scale fire behavior is based on the purely stochastic small-world network model developed by Watts et Strogatz in the end of the nineties to account for both short-range and long-range connections, between adjacent and remote compartments. To finely describe the dynamics of fire, the original network model will be extended by incorporating a weighting procedure on sites, the weights being determined from the characteristic times of heat transfer from compartment to compartment: wall conduction, hot smoke flow through corridors, openings and ventilation pipes, cable trays. This determination will be made from specific lab-scale experiments -by exposing both homogeneous and composite wall panels to incident radiant heat flux representative of fire conditions- and from numerical simulations of fire behavior and its interaction with the water spray using a deterministic macroscopic two-phase model. Complementary experiments will be conducted in a dedicated fire box in order to validate the macroscopic model, but also to collect basic data on the level of thermal stress the structure may undergo. Concept validation consists of two steps. First, we will use results obtained from experiments conducted in the submarine part of the USS SHADWELL. These experiments involved fire propagation in a few compartments and the operation of a water spray system. Second, the partners will have to define an amorphous polydisperse network composed of a large number of compartments. A sensitivity analysis will be carried out in order to identify and classify the most influential parameters of the fire propagation model, and to study the response of the system to the variations of these parameters. The capability of the model to elaborate fire risk mapping and to evaluate network properties will be demonstrated by means of a statistical study. Network properties include percolation threshold, super-nodes (highly-connected nodes) and critical channels along which the fire will propagate preferentially. Evaluating network properties should help in developing better strategies to reduce fire consequences. The present project is a preliminary phase of a long-term project, intended to provide designers and managers with a decision making tool allowing them to reduce the vulnerability of buildings and infrastructure and to allocate fire-fighting resources to maximize public and firefighter safety, reduce environmental impacts, and lower fire-fighting costs.