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Le LiDAR 3D est une technique d’imagerie active qui délivre une information tridimensionnelle des objets en haute résolution. Elle bénéficie de nombreux avantages comme la faible sensibilité à l’éclairement naturel ou à l’environnement opérationnel pour des applications de navigation autonome ou de cartographie précise.

Fast NVH analysis from the start of the motor design is important to speed up product development by avoiding major NVH issues later. In this paper, different methods for electric motor noise and vibration predictions are proposed for different stages in the design process. The results are compared to previous experimental validation [1]. The first method combines electromagnetic finite element analysis to calculate the forces, with analytical models for the stator vibration and acoustic response [2]. This requires minimal structural design data, and can be carried out rapidly, allowing the exploration of many design possibilities in the early design stage, and is implemented in Ansys Motor-CAD. This is compared with the full structural finite element analysis (FEA) [1]. It is shown that the fast analytical NVH process provides a good prediction for the motor noise level early in the design process. The structural FEA approach provides additional information about the structural response at a later stage to refine the design. The use of frequency response functions (FRF) derived from the structural FEA are demonstrated, allowing the rapid calculation of noise results from the electromagnetic forces.

International audience; Aims: Mechanical complications (MC) (i.e., free wall rupture (FWR), papillary muscle rupture (PMR) and ventricular septal rupture (VSR)) are rare complications of ST- elevation acute myocardial infarction (STEMI). Incidence of MC according to pre-hospital delay remains unknown. We aimed to determine the rates of MC according to pre-hospital delay.Methods: Analysis was conducted on the MODIF registry data. Patients were allocated to four groups according to pre-hospital delay: 0 to 12 h, 12 to 24 h, 24 to 36 h and 36 to 48 h.Results: 6185 patients with complete data were analyzed. Mean age was 64.1 years old and 75.7% of patients were males. Eighty-three patients (1.34%) presented with MC: 44 (0.71%) experienced a FWR, 17 (0.27%) a PMR, and 22 (0.36%) a VSR. Global rates of MC were 0.82%, 1.43%, 1.24% and 5.07% in the four groups of pre-hospital delays - 0 to 12 h, 12 to 24 h, 24 to 36 h and 36 to 48 h - respectively (p < 0.001). In-hospital mortality rates were high: 44.2%, 47.1% and 54.6% for FWR, PMR and VSR, respectively. In multivariate analysis, factors independently related to the occurrence of MC were older age, female sex, simultaneous COVID-19 infection, absence of dyslipidemia, initial TIMI flow 0 or 1 in the culprit artery, 36 to 48 h-pre-hospital delay and absence of revascularization by percutaneous coronary intervention (PCI) with stent implantation.Conclusion: The probability of MC in STEMI increases with pre-hospital delay. Mechanical complications of STEMI remain associated with a very poor prognosis.

The numerical prediction of pressure drop within wall-bounded flow domains at high Reynolds numbers ( Re ) using a large-eddy simulation (LES) approach is a challenging task for industrial applications because the fluid domain is usually underresolved. A lattice Boltzmann method (LBM) with Bhatnagar, Gross and Krook (BGK) collision operator coupled with the Smagorinsky–Lilly turbulence model is used to model these wall-bounded turbulent flows. The near wall region is modelled using wall functions to decrease the required mesh resolution for high Re . The influence of different velocity boundary approaches and wall functions is investigated for the benchmark bi-periodic fully developed turbulent channel flow for friction Reynolds numbers ( Re τ ) of 1000, 2000 and 5200. This benchmark case is validated against direct numerical simulation (DNS) results for turbulent statistics of 1st and 2nd order. Based on this validation, the pressure drop of an industrial Coriolis mass flowmeter is compared to experimental data for Re up to 127 800. The error of the pressure drop calculation in underresolved grids is reduced by two orders of magnitude in comparison to a no-slip approach for curved boundaries.

International audience; An emerging rectangular obstacle placed in a laminar boundary layer developing under a free-surface generates three vortical structures: a horseshoe vortex (HSV) in front of the obstacle, a wake downstream and two lateral recirculation zones at its sides. The present work investigates, through PIV measurements, the effect of the obstacle elongation (length over width ratio L/W) on the HSV, which is partly indirect through the modification of the two other vortical structures. Horizontal velocity fields in the near-bottom region show that an increase of the obstacle elongation leads to a higher adverse pressure gradient in front of the obstacle, and in consequence, to the longitudinal extension of the HSV. This modification of geometry, in turn, impacts the vortex dynamics of the HSV. On top of that, maps of spectra and oscillation direction obtained from velocity fields indicate that each of the three structures (HSV, wake and lateral recirculation zones) exhibits a proper oscillation frequency. As the oscillation associated to the wake is energetically dominant and is strong enough to travel upstream, it impacts the HSV dynamics for sufficiently short obstacles.

Systems of care have been challenged to control progression of the COVID-19 pandemic. Whether this has been associated with delayed reperfusion and worse outcomes in French patients with ST-segment elevation myocardial infarction (STEMI) is unknown.Aim: To compare the rate of STEMI admissions, treatment delays, and outcomes between the first peak of the COVID-19 pandemic in France and the equivalent period in 2019.Methods: In this nationwide French survey, data from consecutive STEMI patients from 65 centres referred for urgent revascularization between 1 March and 31 May 2020, and between 1 March and 31 May 2019, were analysed. The primary outcome was a composite of in-hospital death or non-fatal mechanical complications of acute myocardial infarction.Results: A total of 6306 patients were included. During the pandemic peak, a 13.9±6.6% (P=0.003) decrease in STEMI admissions per week was observed. Delays between symptom onset and percutaneous coronary intervention were longer in 2020 versus 2019 (270 [interquartile range 150-705] vs 245 [140-646]min; P=0.013), driven by the increase in time from symptom onset to first medical contact (121 [60-360] vs 150 [62-420]min; P=0.002). During 2020, a greater number of mechanical complications was observed (0.9% vs 1.7%; P=0.029) leading to a significant difference in the primary outcome (112 patients [5.6%] in 2019 vs 129 [7.6%] in 2020; P=0.018). No significant difference was observed in rates of orotracheal intubation, in-hospital cardiac arrest, ventricular arrhythmias and cardiogenic shock.Conclusions: During the first peak of the COVID-19 pandemic in France, there was a decrease in STEMI admissions, associated with longer ischaemic time, exclusively driven by an increase in patient-related delays and an increase in mechanical complications. These findings suggest the need to encourage the population to seek medical help in case of symptoms., Contexte. Les systèmes de santé à travers le monde ont été fortement mis à l’épreuve afin de contrôler la progression de l’épidémie de la COVID-19. L’éventualité que la réorganisation des soins ait pu influencer les délais de reperfusion ou le devenir des patients présentant des syndromes coronaires aigus avec sus-décalage du segment ST (SCA ST +) n’a pas été explorée en France.Objectif. Comparer le taux d’admissions pour SCA ST+, les délais de traitement et enfin le devenir de ces patients entre la première vague épidémique de la COVID-19 et pendant la période similaire en 2019.Méthodes. Dans ce registre national multicentrique, les patients avec SCA ST+ provenant de 65 centres français admis en urgence pour revascularisation entre le 1e mars et le 31 mai 2020 et entre le 1e mars et le 31 mai 2019 ont été analysés. Le critère de jugement principal était un critère composite regroupant la mortalité intrahospitalière toute cause confondue et les complications mécaniques en lien avec l’infarctus.Résultats. Un total de 6 306 patients ont été inclus. Pendant le pic de la pandémie une réduction de 13,9 ± 6,6 % (P = 0,003) des admissions pour SCA ST+ a été observée par semaine. Les délais entre l’apparition des symptômes et l’angioplastie percutanée était significativement augmentés 270 (150−705) versus 245 (140−646) minutes (P = 0,013). Cette augmentation était exclusivement liée à une augmentation du temps entre l’apparition des symptômes et le premier contact médical 121 (60−360) en 2019 versus 150 (62−420) minutes en 2020 (P = 0,002). Durant cette période a été constaté un plus grand nombre de complications mécaniques (0,9 % vs 1,7 % (P = 0,029) conduisant à une augmentation significative de notre critère de jugement principal 112 patients (5,6) en 2019 vs 129 (7,6 %) en 2020 (P = 0,018).Conclusions. Pendant le premier pic de la pandémie il a été constaté : une diminution du taux de SCA ST + associé à un temps d’ischémie prolongé, poussé par l’augmentation du temps entre l’apparition des symptômes et le premier contact médical et enfin un plus grand nombre de complications mécaniques. Ces observations suggèrent la nécessité d’encourager la population à consulter au moindre symptôme inquiétant.

Le LiDAR 3D est une technique d’imagerie active delivrant une information spatiale tridimensionnelle d’un objet. Une telle technique apporte des reponses nouvelles tant pour la navigation que pour la cartographie. Cet article a pour objectif de comprendre la physique de la mesure associee a cette technique et ses principaux modes de fonctionnement : mesure de temps de vol, modulation d’amplitude ou de frequence. Suit une presentation des technologies utilisees. Enfin, deux utilisations sont detaillees afin d’illustrer le potentiel du LiDAR 3D pour des applications de navigation a courte / moyenne distance ou de cartographie a plus longue portee (au-dela du kilometre).

This experimental laboratory study presents a detailed analysis of the surface oscillations inside a square cavity connected laterally to an open channel. For an approaching steady and one-dimensional main stream with a high (subcritical) Froude number, interaction with the dead water volume in the cavity area triggers high-amplitude free-surface oscillations, denoted seiches. In the present study, the length of the square cavity equals half of the combined width of the cavity and the main channel. This particular geometry enables two-dimensional or bidirectional seiching with standing waves being excited in both directions simultaneously. In this work, the (relative) magnitude of the different seiching modes (transverse and longitudinal) is measured and analyzed for a range of flow conditions with varying Froude number. The current experimental results confirm earlier findings indicating that the magnitude and dominance of the longitudinal seiching mode (with respect to the transverse mode) grows with increasing Froude number of the main stream. Additionally, a wavelet analysis in the time and frequency domains reveals that the amplitude of the two modes fluctuates significantly in the course of a single experiment, such that seiching cannot be considered a steady phenomenon. Therefore, two alternative strategies are presented to quantify the amplitude of both modes using a more time-localized approach that is less affected by the intermittent behavior of seiching. Although more research is necessary to fully understand what determines the dominant mode at a given moment, an in-depth analysis of the surface recordings at multiple locations in the cavity suggests that the transition from transverse to longitudinal seiching (and vice versa) is related to the phase difference between the bidirectional seiching waves at the (inner) corners of the cavity.

International audience; Predicting mixing processes, especially transverse mixing, downstream of river confluences, is necessary for assessing and modeling the fate of pollutants transported in river networks, but it is still challenging. Typically, there is a lack of transverse mixing solutions implemented in 1-D hydrodynamical models widely used in river engineering applications. To investigate the mixing processes developing downstream of a medium-sized river confluence, three high-resolution in situ surveys are conducted at the Rhône-Saône confluence in France, based on geolocated specific conductivity and hydroacoustic measurements. Contrasting mixing situations are observed depending on hydrological conditions. In some cases, the two flows mix slowly due to turbulent shear at their vertical interface. This can be modeled by an analytical solution of the advection-diffusion equation. In other cases, the waters from one of the two tributaries move under the waters of the other tributary. The induced local circulation enhances transverse mixing but not vertical mixing and the flow remains stratified vertically, which may be missed when surface or satellite images are analyzed qualitatively. Stratification may be predicted by comparing the time scales for shear and density-driven adjustment. Shear-dominated transverse mixing of depth-averaged concentrations can be predicted analytically and implemented in 1-D hydrodynamical models. However, the initiation of apparently rapid transverse mixing due to density-driven circulation remains to be better understood and quantified. Plain Language Summary Predicting how waters mix downstream of river confluences is necessary for assessing and modeling the fate of pollutants transported in river networks, but it is still challenging. Typically, there is a lack of transverse mixing solutions implemented in models widely used in river engineering applications. To investigate the mixing processes developing downstream of a medium-sized river confluence, three high-resolution in situ surveys are conducted at the Rhône-Saône confluence in France. Contrasting slow or rapid mixing situations are observed depending on hydrological conditions. The transverse mixing of depth-averaged concentrations can be predicted analytically and implemented in 1-D hydrodynamical models. However, the initiation of rapid transverse mixing due to difference in fluid density remains to be better understood and quantified.

This paper proposes a new design strategy for Synchronous Reluctance machines, with cooperative design in the two environments SyR-e and Motor-CAD. The paper proposes to use the open-source SyR-e for initial, equation based design of the machine. Then, the design is validated and refined in Motor-CAD, in multiple physical domains. This synergy complements both design environments and turns into a comprehensive design package, not yet available in the literature, assembling accessible design equations, magnetic and mechanical FEA and drive operating profiles evaluation to the trademark thermal analysis of Motor-CAD. The cooperative design strategy is described in the paper with reference to the case of a Pure Synchronous Reluctance motor prototype for vehicular traction.

International audience

International audience; no abstract

This paper deals with an innovative optimization procedure for multi-physics analysis of electrical machines using Motor-CAD and optiSLang software. The approach is based on cutting edge sensitivity analysis, meta-modeling and optimization techniques that enable motor designers to leverage the design space and to find an optimum solution with respect to a given specification. A detailed optimization workflow is developed and applied to the design of an interior PM motor for a PHEV application. In particular, the electric motor is optimized to give maximum efficiency, minimum size and minimum cost, while achieving specific peak and continuous torque-speed characteristics.

The dynamics of high Reynolds number floating objects in one- and two-dimensional free surface flows are studied theoretically and experimentally. The results can greatly simplify the analyses and computations of the motion of floating objects at high particulate Reynolds number, first by identifying a characteristic distance, scaling the length of the acceleration phase, and then by showing that once the flow velocity is reached the object is transported as a passive tracer.

High-return-period floods involve complex flows over large floodplains covered with different types of resistive elements, from bed roughness to large emerging obstacles. In order to charac...

This paper provides, through laboratory experiments, the flow discharge passing from a flooded street to a building area through different types of damaged openings (a door, a window and a gate) along with a sensitivity analysis of this discharge to the presence of obstacles or facade details. Four flow regimes in the street are tested, representing a high or low street slope with a high and low water depth. These flows resemble that over rectangular side weirs, with the major difference that obstacles are usually located near the opening in the street or on the facade. 26 configurations of obstacles are then included, one after the other, and their impact on the flow intrusion is measured. For the flow cases without obstacle, the agreement of the semi-analytical equations available in the literature strongly varies from one equation to another. On the other hand, the 220 tested flow cases reveal that the location of the obstacle with regards to the opening strongly modifies the impact of the obstacles, that increasing the Froude number tends to increase the impact of the obstacles and that obstacles have a higher impact on the intrusion discharge through a window than to a door or a gate. Finally we conclude that the largest obstacles (typically parked cars) located in the vicinity of openings should be somehow included in operational numerical models that calculate urban floods for a fair prediction of the intrusion discharge.

Lateral cavities adjacent to open-channel flows are dead zones located on one side of a main stream. With an approaching flow with a high (subcritical) Froude number, the free-surface of the dead-zone oscillates with high amplitudes and generates a so-called seiche. This configuration is reproduced in a rectangular cavity (with an interface length equal to the main stream channel width) in which the impact of the three dimensionless parameters (Froude number, dimensionless water depth, and geometrical aspect ratio) affecting the seiche is studied experimentally. For all configurations, a natural mode of the cavity is observed, this mode being either longitudinal or transverse, except in the case of a square cavity where bi-directional seiching occurs. Moreover, we show that while the approaching Froude number (0.55 < Fr < 0.7) and dimensionless water depth do not affect the oscillation mode, the selected natural mode is strongly dependent on the geometrical aspect ratio of the cavity. For narrow cavities (small [W + b]/b with W and b the cavity and channel widths, respectively), a longitudinal mode occurs while for wider cavities transverse modes occur, with an increasing number of nodes as the width of the cavity increases. Finally, measuring the time-resolved 2-dimensional field of free-surface deformation in the cavity and the adjacent main stream permits us to identify the vortices shed along the mixing layer at the cavity/main stream interface and thus to analyze the synchronization between the surface oscillation and vortex shedding (at the upstream edge) and impinging (at the downstream edge) processes.

This article aims at predicting the oscillation frequency of open-channel lateral cavities, which are common sheltered zones of riverine environments, and have important ecological impact. Using a theoretical analysis based on an existing model for acoustic cavities and a free-surface lateral cavity experiment, we show that the vortex shedding in the mixing layer between the cavity and the open channel is always constrained by gravity waves even for low Froude numbers ( ). This expands previous results from the literature showing the impact of gravity waves on the vortex shedding frequency for high Froude number ( ). Measurements of the free-surface oscillation and transverse velocity oscillation frequencies reveal a unique frequency along the mixing layer, equal to the free-surface oscillation frequency anywhere in the cavity. Hence, it is shown that the vortex shedding frequency in an open-channel lateral cavity always equals a match between a natural frequency of the cavity and a solution of the feedback model developed herein for low to moderate Froude numbers.

International audience; In the past ten years, governments from the European Union have been encouraged to collect volume and quality data for all the effluent overflows from separated stormwater and combined sewer systems that result in a significant environmental impact on receiving water bodies. Methods to monitor and control these flows require improvements, particularly for complex Combined Sewer Overflow (CSO) structures. The DSM-flux (Device for Stormwater and combined sewer flows Monitoring and the control of pollutant fluxes) is a new pre-designed and pre-calibrated channel that provides appropriate hydraulic conditions suitable for measurement of overflow rates and volumes by means of one water level gauge. In this paper, a stage-discharge relation for the DSM-flux is obtained experimentally and validated for multiple inflow hydraulic configurations. Uncertainties in CSO discharges and volumes are estimated within the Guide to the expression of Uncertainty in Measurement (GUM) framework. Whatever the upstream hydraulic conditions are, relative uncertainties are lower than 15% and 2% for the investigated discharges and volumes, respectively.

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).

A novel concept of a surge wave energy converter for nearshore applications is investigated experimentally. The centimetre-sized prototype developed in this work represents a proof of concept of a submerged system, which entails a hybrid transduction solution for the electrical conversion of wave energy, that uses piezoelectric elements (PZEs) and dielectric elastomer generators (DEG). The idea is to exploit the horizontal pressure gradient and horizontal water velocity underneath the waves to compress the PZE and inflate each half wave period a soft variable capacitance, which composes the DEG. The electrical charges created by the PZE are used to polarize the DEG, which is able to multiply the input energy. This hybridization is conceived to allow the system to generate electrical energy from waves without conventional high voltage supplies, thus reducing production costs and allowing standalone clean electrical generation. The article provides the preliminary fluid-mechanical measurements performed in a wave flume with a first version of the prototype and supported by a model comprising the fluid/structure interaction, the materials response, and the electrical operations. An estimation of the output energy of a small-sized prototype in constant charge mode is computed, and perspectives for optimizing the system are presented.

Turbulent mixing layers associated with streamwise uniform and non-uniform flows in compound channels (main channel with adjacent floodplains) are experimentally investigated. The experiments start with uniform flow conditions. The streamwise non-uniformity is then generated by imposing an imbalance in the upstream discharge distribution between main channel (MC) and floodplains (FPs), keeping the total discharge constant, which results in a transverse depth-averaged mean flow. This study firstly aims at assessing the effect of a transverse flow on the mixing layer and coherent structures that form at the MC/FP interfaces. A wide range of initial velocity ratio or dimensionless shear between MC and FP is tested. The study secondly aims at assessing the effect of this velocity ratio on the mixing layer, for a fixed vertical confinement of flow. The total discharge was then varied to quantify the confinement effect. The results show that, far from the inlet section, Reynolds-stresses increase with local velocity ratio for a fixed confinement, and decrease with confinement for a fixed velocity ratio. It is also shown that, irrespective of confinement, the existence of quasi-two-dimensional coherent structures is driven by velocity ratio and the direction and magnitude of transverse flow. These structures cannot develop if velocity ratio is lower than 0.3 and if a strong transverse flow towards the MC occurs. In the latter case, the transverse flow is the predominant contribution to momentum exchange (compared with turbulent mixing and secondary currents), convex mean velocity profiles are observed, preventing the formation of quasi-two-dimensional structures.

The authors measured and computed the hydrodynamics and passive scalar dispersion in 90-degree open channel confluences over flat and degraded beds with a dominant upstream or tributary inflow. The present discussion essentially deals with the direction of rotation of the secondary currents, reported for the flat bed configuration with dominant tributary inflow. This rotation direction is indeed surprisingly opposite to the ones reported in the literature, both from calculations and measurements, even if present geometry slightly differs from literature geometries.

In this paper, a new elastic lidar inversion equation is presented. It is based on the backscattering signal from a surface reference target (SRT) rather than that from a volumetric layer of reference (Rayleigh molecular scatterer) as usually done. The method presented can be used when the optical properties of such a layer are not available, e.g. in the case of airborne elastic lidar measurements or when the lidar-target line is horizontal. Also, a new algorithm is described to retrieve the lidar ratio and the backscattering coefficient of an aerosol plume without any a priori assumptions about the plume. In addition, our algorithm allows a determination of the instrumental constant. This algorithm is theoretically tested, viz. by means of simulated lidar profiles, and then using real measurements. Good agreement with available data in the literature has been found.

Executive Summary corresponding to the ReFreeDrive project deliverable D3.4: "CR-IM Full Design Report (Including CAD) for Inner and Outer Rotor Designs"

Executive Summary corresponding to the ReFreeDriveMidterm Project Report

Commercial Unmanned aerial vehicle (UAV) industry, which is publicly known as drone, has seen a tremendous increase in last few years, making these devices highly accessible to public. This phenomenon has immediately raised security concerns due to fact that these devices can intentionally or unintentionally cause serious hazards. In order to protect critical locations, the academia and industry have proposed several solutions in recent years. Computer vision is extensively used to detect drones autonomously compared to other proposed solutions such as RADAR, acoustics and RF signal analysis thanks to its robustness. Among these computer vision-based approaches, we see the preference of deep learning algorithms thanks to their effectiveness. In this paper, we are presenting an autonomous drone detection and tracking system which uses a static wide-angle camera and a lower-angle camera mounted on a rotating turret. In order to use memory and time efficiently, we propose a combined multi-frame deep learning detection technique, where the frame coming from the zoomed camera on the turret is overlaid on the wide-angle static camera’s frame. With this approach, we are able to build an efficient pipeline where the initial detection of small sized aerial intruders on the main image plane and their detection on the zoomed image plane is performed simultaneously, minimizing the cost of resource exhaustive detection algorithm. In addition to this, we present the integral system including tracking algorithms, deep learning classification architectures and the protocols.

The present report covers the electro-magnetic design analysis for Copper-Rotor Induction Motors (CR-IM) for inner and outer rotor for traction systems in Electric Drive Technologies (EDT). This is one of the technical solutions investigated by ReFreeDrive project. In Work Package 3, Inner Rotor (IR) and Outer Rotor (OR) induction motors configurations with cage built using die-casted or fabricated rotor technologies are proposed. When IR topology is used in combination with high rotational speed, i.e. ≥ 20000rpm, the torque density and the specific power are increased. Similarly, an OR topology can be used at lower rotational speed, i.e. ≤ 18000rpm, the increase in torque density and specific power is guaranteed due to the inherent higher diameter in the motor airgap. From a mechanical point of view, the mechanical analysis confirmed that the proposed IR and OR designs are within the maximum acceptable limits for the mechanical stress and natural frequencies that may occur. The outcome of this report provides clear guidelines on the CR-IM solutions for EDTs and identifies the optimum candidates design solutions for IR and OR topologies.&nbsp

International audience; Detached hydraulic jumps are major features of supercritical open-channel flows interacting with emerging obstacles. Such a flow pattern exhibits strong similarities with shock waves detached in front of bluff bodies in supersonic aerodynamic flows. This paper aims at evaluating the capacities of an analytical model, adapted from supersonic aerodynamics, to predict the hydraulic jump detachment length. The analytical predictions are compared to the measured hydraulic jumps from two experiments: (i) a uniform supercritical open-channel flow that skirts a mounted and emerging obstacle (with a horseshoe vortex) and (ii) a mounted and emerging obstacle moving at constant velocity in water at rest (without a horseshoe vortex). Moreover, numerical calculations of supercritical flow skirting emerging obstacles are undertaken, with a free-slip condition at the bed to remove the horseshoe vortex, while keeping the detached hydraulic jump. The comparison of the detachment lengths of these experimental, analytical, and computed hydraulic jumps reveals that two types of detachment lengths can be defined. The detachment length visible on experiments corresponds to the toe of the hydraulic jump, while the detachment length predicted by the analytical model rather corresponds to the location of flow regime transition from the supercritical to subcritical regime. The present work thus validates the analytical model for predicting the location of flow regime transition (for configurations without a horseshoe vortex) but not for predicting the toe of the hydraulic jump. We finally confirm the strong connections between two distinct phenomena: a hydraulic jump in water flow and a shock wave in gas flow.

International audience; The drag reduction method using polymer additives is a common strategy to minimize friction losses when carrying fluids (water, oil, or slurries) in pipes over long distances. Previous studies showed that the interactions between the polymer and turbulent structures of the flow tend to modify the streamwise velocity profile close to the walls by adding a so-called elastic sublayer between the classical viscous and log layers. The gain in linear head losses can reach up to 80% depending on the roughness of the walls and the concentration of polymers. The application of this technique to sewers and the subsequent gain in discharge capacity motivated this work to quantitatively measure the drag reduction in classical open-channel flows. Three measurement campaigns were performed in a dedicated long flume for several water discharges and several polymer concentrations: backwater curves over smooth and rough channel walls (including velocity and turbulent shear-stress profiles) and flows around emerging obstacles. The addition of polymers, even in limited concentrations, allowed a high friction decrease with the typical Darcy-Weisbach coefficient reduced by factors of 2 and 1.5, respectively, in smooth and rough walls configurations without obstacles, but without strong modifications of the nondimensional velocity profiles. In contrast, when adding emerging obstacles, the flow was unaffected by the inclusion of polymers, in agreement with the prediction of the literature. The drag reduction method by addition of small concentrations of polymers thus appears to be a promising technique to increase flow conveyance in open-channel flows.

International audience; The flow pattern within a storage zone governs the efficiency of passive scalar accumulation , spreading and homogenization. The present paper aims at characterizing experimentally the evolution of this flow pattern in a simplified open-channel lateral cavity with twenty increasing horizontal aspect ratio, focusing on the transition between the different flow patterns. Four main flow types are observed and detailed herein with, as the aspect ratio gradually increases: two cells aligned along the main stream axis, one unique cell, two cells aligned transversally and finally a more complex 3D pattern in the second cell. Quantitative characteristics of these cells are extracted from the velocity fields measured in the cavity. A 2D angular momentum balance is then applied that explains the transitions between these flow types and proves to be able to predict the flow patterns reported in the literature.

International audience

International audience; This paper addresses pilot error due to distractions, lack of situational awareness and misjudgment of separation during taxi manoeuvers. A display is being developed to minimize these errors and assist pilots to determine safe passage while navigating during taxi. Part of the development consisted of the implementation of a tracking algorithm-based on the particle filter-which is being presented in this paper. The tracking algorithm tracks obstacles that have been detected and reconstructed using stereo vision techniques. Afterwards, the tracked obstacles are highlighted on a display. Experiments show that the algorithm successfully detects and tracks aircraft in an airfield.

This paper deals with the design of a Synchronous Reluctance motor for full-electric vehicle applications. In particular, the design is focused on premium vehicles and aims at the development of rare-earth free electric motor technologies featuring low cost manufacturing. Different solutions are proposed and compared with focus on the rotor design; the investigated topologies employ asymmetric rotor structures with "fluid shaped" barriers without radial ribs to maximize the average torque and minimize the torque ripple. As this choice is very critical for the mechanical strength of the rotor core at high speed, it has been decided to fill the flux barriers with epoxy adhesive resin. The use of the resin has required an accurate mechanical analysis in order to assess the rotor robustness at high speed.The paper presents the performances of the optimized design and the efficiency and torque ripple maps: moreover, useful information on the use of the epoxy resin in the synchronous reluctance motor are provided.