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International audience; Emergency department overcrowding is a global issue that poses a great threat to patient health and safety. The timeliness of medical services provided to patients is crucial to emergency departments as it directly impacts the mortality and morbidity of urgent patients. However, critical resources (e.g., doctors and nurses) are typically constrained due to the limited financial budget. Thus, hospital administrators may need to investigate solutions to improve the efficiency of the emergency department. In this work, we study the dynamic problem of scheduling patients to doctors, aiming at minimizing the total weighted tardiness. We propose a simple reoptimization heuristic based on multiple queues of patients in accordance with their urgency levels, and then combine it with an effective variable neighborhood search. We also propose a scenario-based planning approach that uses sampled scenarios to anticipate future events and the variable neighborhood search to schedule patients. The methods are adapted to handle a problem variant where information on arrival time and urgency level of some patients can be received in advance by the emergency department. With a comprehensive computational study on two sets of realistic instances from Hong Kong SAR of China and Italy, we validate the performance of the proposed methods, evaluating the benefits of having more doctors and receiving early information.

International audience; The increased focus on supersonic and hypersonic flows necessitates methods to study such flows in laboratory-based facilities, thus motivating researchers to find effective, efficient, and affordable methods to produce them in laboratories. It is desirable for the rocket nozzles to operate efficiently at different altitudes, which made the Altitude Compensating Nozzles emerge as a solution. In this work, we propose a new design for such nozzles, namely, the ringed nozzle. The proposed nozzle consists of a stack of parallel rings that serve as a nozzle with bleeding slots. This design can be utilised to obtain different exit Mach numbers and attain the desired performance according to the pressure ratio, serving as an Altitude Compensating Nozzle. The stack of rings might be altered to tailor nozzle shape and area ratio corresponding to the nozzle requirement. The nozzle is analysed from an engineering perspective by comparing the thrust coefficient and specific impulse, and the numerical simulations show promising results.

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.

International audience; In this article, we introduce a method to exploit ultra-high dielectrophoresis (UHF-DEP) with a microfluidic radio frequency device able to sort biological cells by deflecting the trajectory of the targeted population in a continuous flow. This study highlights the capability of a high frequency lab-on-chip implemented UHF-DEP cytometer to isolate cancer stem cells (CSCs). Actually, CSCs sorting by an efficient, fast and low-cost method remains an issue. Above 20 MHz, the intracellular dielectric properties of cells determine the dielectrophoretic behavior of cells and is then very sensitive to the cell cytoplasm content. The proposed cell sorting principle exploits the combination of the fluidic drag and the repulsive dielectrophoretic forces in order to isolate CSCs hidden within differentiated cancer cells. We previously demonstrated the UHF-DEP behavior of cells, as a new type of electromagnetic biomarkers to discriminate cancer stem cells among a tumor population from colorectal cancer cell line.

International audience; Solid oxide electrolysis cells (SOEC) are a promising energy conversion technology for the production of green hydrogen via steam electrolysis. However, performance loss remains a bottleneck for large-scale commercialization. Here, we investigate the different types of degradation occurring in a state-of-the-art cell composed of La0.6Sr0.4Co0.2Fe0.8O3-Ce0.8Gd0.2O2 (LSCF-GDC) composite for the oxygen electrode, GDC for the barrier layer, Y0.16Zr0.84O1.92 (8YSZ) for the electrolyte and Ni-YSZ for the fuel electrode. Electrochemical impedance spectra measured before and after operation at 750 °C for 2000 hours at -1 A cm-2 in SOEC mode revealed no significant evolution for the oxygen electrode contribution. To investigate potential degradation of this electrode, we performed multi-modal chemical imaging based on synchrotron X-ray diffraction (µ-XRD) with a resolution at the micrometer-scale. In addition, we monitored the evolution of the chemical composition and chemical environment before and after ageing using laboratory X-ray photoelectron spectroscopy (XPS). All these analyses revealed a slight evolution of the crystal lattice parameter in the oxygen electrode and the inter-diffusion layer. It was also found that Sr segregation accelerates with ageing. However, more severe ageing conditions and/or longer ageing durations are required in order to observe an effect on the performance.

Due to their periodic nature, metasurfaces used to perform anomalous reflection raise parasitic harmonic reflections. We show a classical synthesis example of such a structure and highlight its limitations. Floquet analysis and its associated simulation environment are exploited to understand the origin of these parasitic reflections and to mitigate them. The proposed method is based on the optimization of the metasurface periodic pattern: the supercell. A predictive method is built to calculate radar cross-section patterns from supercell Floquet simulation, avoiding dealing with heavy simulations. The proposed model, the optimization outputs, and the general results are exposed in details. Different cases are also discussed to prove the repeatability of the proposed method. An earlier version of this paper was presented at the European Microwave Conference and was published in its proceedings.

International audience; The structural and radio frequency (RF) design and optimization of a large deployable faceted reflectarray (RA) generating double polarization contour beam are presented in this work. The issue addressed is the thermoelastic stability of large RAs and the impact of the thermoelastic deformation (TED) under transverse thermal gradient on the RA performances. Finite element TED analysis is conducted on a deployable RA with self-standing structures, demonstrating the detrimental effects of the in-orbit TED impact on the RA performances, estimated to be above 3 dB losses. To this extent, a novel structural solution is proposed, based on the use of reliable mechanical support capable to mitigate the TED. The mechanical design reorientation is contingent on the RF design reformulation. The proposed novel mechanical and RF co-design concept and methodology allows the conception of a low-profile, thermo-structurally stable RA with compliant radiation patterns and high cross-polarization discrimination in the worst case thermal load. This methodology is based on a direct optimization of nine-panel faceted RA composed of advanced high-order Phoenix cells directly optimized to fulfill the contoured beam requirements and by respecting the local periodicity requirements of the layout.

We propose a dynamic augmentation scheme for the asymptotic solution of the nonlinear algebraic loops arising in well-known input saturated feedbacks typically designed by solving linear matrix inequalities (LMIs). We prove that the existing approach based on dynamic augmentation, which replaces the static loop by a dynamic one through the introduction of a sufficiently small time constant, works under some restrictive sufficient well-posedness conditions, requiring the existence of a diagonal Lyapunov matrix. However it can fail in general, even when the algebraic loop is well-posed. Then, we propose a novel approach whose effectiveness is guaranteed whenever wellposedness holds. We also show how this augmentation allows preserving the guaranteed region of attraction with Lyapunovbased designs, as long as a gain parameter is sufficiently large. We finally propose an adaptive version of the scheme where this parameter is adjusted online. Simulation results show the effectiveness of the proposed solutions.

International audience; Abstract This article is focused on the application of plasma technology for the development of microwave lens antennas with electronically controllable radiation gain. With this aim, the analytical background and design procedure for designing a biconcave lens based on plasma dielectric material are presented. The procedure is used to design a plasma lens antenna with a pyramidal horn feed. The effect of switching the designed lens ON and OFF on the radiation gain of the lens antenna is investigated. It is also shown that the plasma frequency of the lens can be used to dynamically adjust the radiation gain. A one-dimensional version of the proposed plasma lens operating at 10 GHz has been developed to validate the concept. Experimentally measured characteristics of a fabricated prototype of the lens antenna based on commercially available fluorescent lamps confirm the presented design procedure and numerical results. The results also show that changing the plasma frequency of the lens can be used to adjust the radiation gain of the proposed lens antenna.

preprint: https://doi.org/10.21203/rs.3.rs-1622610/v2; International audience; Sample-return missions allow the study of materials collected directly from celestial bodies, unbiased by atmospheric entry effects and/or terrestrial alteration and contamination phenomena, using state-of-the-art techniques which are available only in a laboratory environment—but only if the collected material stays pristine. The scarcity of outer-space unaltered material recovered until now makes this material extremely precious for the potential scientific insight it can bring. To maximize the scientific output of current and future sample-return missions, the scientific community needs to plan for ways of storing, handling, and measuring this precious material while preserving their pristine state for as long as the ‘invasiveness’ of measurements allows. In July 2021, as part of the Hayabusa2 (JAXA) “Stone” preliminary examination team, we received several microscopic particles from the asteroid Ryugu, with the goal of performing IR hyper-spectral imaging and IR micro-tomography studies. Here, we describe the sample transfer, handling methods and analytical pipeline we implemented to study this very precious material while minimizing and surveilling their alteration history on Earth.

The recent discovery of superconductivity in paramagnetic UTe2 turns spotlight on a serious candidate for spin-triplet state. To draw a complete picture of the superconducting state in UTe2 precise knowledge of the electronic properties of the 5 f states of Uranium is missing. We report on x-ray absorption and magnetic circular dichroism experiments performed at the U M4,5 edges at 2.7 K. At ambient pressure the 5 f electron count is found to be in-between 2.6 and 2.8. Partial delocalization of the 5 f electrons is further confirmed by the reduced value of the U orbital to spin magnetic moment ratio. The 5 f count is reduced by as large as 7 percent at the transition to a magnetically ordered state at Pc ≈ 1.5 GPa. At pressures above 4 GPa, the 5 f count increases back towards U3+ in the tetragonal phase. The observed “valence instabilities” and their interplay with magnetism seem to be important ingredients to understand the electronic structure in UTe2 in different phases.

International audience; We developed a triggerable ultimate security device capable of physically destroying a memory chip that contains classified data, within a few milliseconds, upon the detection of intrusion.

chapter 15; International audience; In the last decade, GaN has emerged as an excellent material for application in power electronics. The wide energy gap of gallium nitride (3.4 eV) enables high-temperature operation, while the large breakdown field (3.3 MV/cm, 11 times higher than silicon) allows to reach kV-range operation while maintaining a low on-resistance. Thanks to the high mobility of the two-dimensional electron gas at the AlGaN/GaN interface, lateral GaN transistors have a very low on-resistance; commercial products are already on the market, and new technologies are being developed, targeting the 650 V/900 V ranges. Recently, the attention toward vertical GaN transistors has constantly increased: a vertical layout allows to substantially increase current density while taking advantage of the wide bandgap and high breakdown field of GaN. Vertical transistors based on GaN are expected to find application in converters with medium high power levels (>5 to 10 kW), once the technology reaches maturity.This chapter reviews the main properties of GaN-based materials and devices. The first part focuses on the main challenges related to the growth of high-quality GaN epitaxial stacks. The second and the third parts focus on GaN lateral and vertical devices, respectively. Finally, the fourth section describes the trapping and degradation processes that limit the performance and the reliability of GaN transistors, and the related physical mechanisms. This chapter represents an ideal guide for a reader willing to enter the world of GaN devices.

International audience

International audience; In this paper, the static and fatigue behaviors under compression of Multi-Directional (MD) Carbon Fiber Reinforced Polymer (CFRP) laminates with impact damage were investigated. After low-velocity impact performed on three 24-ply Quasi-Isotropic Quasi-Homogeneous (QIQH) laminates having different stacking sequences, the influence of the distribution of interfaces between two plies on the compression after impact and post-impact compression fatigue properties was evaluated. The damages on the surfaces and internal delamination were accessed via visual and optical observation and ultrasonic C-scan inspection. The thermographic approach, which has been developed and validated on numerous non-impacted composite materials, was applied for the rapid determination of the fatigue limit together with the S-N curves of post-impact fatigue specimens.Experimental results showed that with 5 J impact energy, the three stacking sequences gave similar impact results. The residual strengths measured by compression after impact tests were also similar to each other, so did the global damage modes. The determined fatigue limits of impacted specimens of different stacking sequences were nearly identical and the predicted S-N curves were also close to each other despite the exact crack propagation and orientation were not the same, under both compressive static and cyclic loads.

A direct numerical simulation of a moderate adverse pressure gradient turbulent boundary layer flow on a flat plate was performed on a fairly long domain with a Reynolds number from $Re_\theta=2000$ to $Re_\theta=8000$. The mean streamwise velocity profile does not exhibit a clear log region even at the highest Reynolds number. The Reynolds stresses exhibit a well defined peak in the outer region which moves away from the wall before to stabilise at a wall distance of 0.45 boundary layer thickness after evolving over 20 local boundary layer thicknesses. These outer peaks are the consequences of an excess of production over dissipation and they all scale with the shear stress velocity for wall distance $0.2 \delta < y < 0.85 \delta$ . The different terms of the Reynolds stresses equations are analysed in the outer region and the analysis confirms that the leading terms are the same as for a zero pressure gradient turbulent boundary layer except that the production and dissipation are not negligible in the outer region. The most significant contribution of scales smaller than two Taylor scales is on the pressure strain term of the shear stress equation. The probability of the occurrence of small scale vortices conditioned by the presence of an ejection or a sweep shows that the shear stress contained in ejections is associated with the production and transport of near wall vortices away from the wall. The local mean shear generated by the sweeps increases the production of near wall vortices. Lastly, the large scale structures analysed by means of two point correlations of the streamwise fluctuating velocity are shown to be strongly modified by the adverse pressure gradient. The correlation reveals a decoupling between the near wall streaks and the large scale streamwise structures enhanced by the adverse pressure gradient.

Two-dimensional electronic states at surfaces are often observed in simple wide-band metals such as Cu or Ag (refs. 1–4). Confinement by closed geometries at the nanometre scale, such as surface terraces, leads to quantized energy levels formed from the surface band, in stark contrast to the continuous energy dependence of bulk electron bands2,5–10. Their energy-level separation is typically hundreds of meV (refs. 3,6,11). In a distinct class of materials, strong electronic correlations lead to so-called heavy fermions with a strongly reduced bandwidth and exotic bulk ground states12,13. Quantum-well states in two-dimensional heavy fermions (2DHFs) remain, however, notoriously difficult to observe because of their tiny energy separation. Here we use millikelvin scanning tunnelling microscopy (STM) to study atomically flat terraces on U-terminated surfaces of the heavy-fermion superconductor URu2Si2, which exhibits a mysterious hidden-order (HO) state below 17.5 K (ref. 14). We observe 2DHFs made of 5f electrons with an effective mass 17 times the free electron mass. The 2DHFs form quantized states separated by a fraction of a meV and their level width is set by the interaction with correlated bulk states. Edge states on steps between terraces appear along one of the two in-plane directions, suggesting electronic symmetry breaking at the surface. Our results propose a new route to realize quantum-well states in strongly correlated quantum materials and to explore how these connect to the electronic environment.

International audience

International audience; Alloy material selection for sustainable, efficient, and cost-effective use in components is a key requirement for both power generation and aerospace sectors. Superalloys are manufactured using a combination of different elements, selected carefully to balance mechanical performance and environmental resistance to be used in a variety of different service conditions. Therefore, a fundamental understanding of each element is critical to alloy design. In this paper, the interaction of alloy chemistry, particularly chromium as a corrosion-resistant element along with titanium and molybdenum, and their effect on alloys performance for the relevant gas turbine industries were discussed. Based on the findings, the single-crystal alloy is found to be a better corrosion resistant alloy exhibited higher corrosion resistance in comparison to polycrystal alloys and proved that microstructure has a significant impact on alloy performance. This study also established that molybdenum level in chromia former alloys can significantly enhance the corrosion damage.

The present paper deals with both the modeling and the dynamic control of a solar hybrid thermochemical reactor designed to produce syngas through the high-temperature steam gasification of biomass. First, a model of the reactor based on the thermodynamic equilibrium is presented. The Cantera toolbox is used. Then, a model-based predictive controller (MPC) is proposed with the aim of maintaining the reactor’s temperature at its nominal value, thus preserving the reactor’s stability. This is completed by adjusting the mirrors’ defocusing factor or burning a part of the biomass to compensate for variations of direct normal irradiance (DNI) round the clock. This controller is compared to a reference controller, which is defined as a combination of a rule-based controller and an adaptive proportional–integral–derivative (PID) controller with optimized gains. The robustness of the MPC controller to forecast errors is also studied by testing different DNI forecasts: perfect forecasts, smart persistence forecasts and image-based forecasts. Because of a high optimization time, the Cantera function is replaced with a 2D interpolation function. The results show that (1) the developed MPC controller outperforms the reference controller, (2) the integration of image-based DNI forecasts produces lower root mean squared error (RMSE) values, and (3) the optimization time is significantly reduced thanks to the proposed interpolation function.

Greenery strategies and shaded pedestrian passages have become requirements for designing smart cities in developed countries. One of the most difficult challenges for designers is designing cities in hot and arid climates while maintaining a proper level of outdoor thermal comfort. The designers focus on creating a comfortable climate for people throughout the afternoon under the hot sun, particularly in countries where summer temperatures rise excessively for more than seven months per year, as in Iraq. This study compares two Baghdad cities: Haifa Street, which was built in 1984 on a Western design pattern, and the second city, which the researchers designed according to the requirements of construction in an arid climate, such as street and building orientation, aspect ratio, sky view factor, the influence of courtyards, and the role of albedo. The second city is planned to cover the same total area as the first. The results of the two cities were compared and analyzed using ENVI-met software. To conduct a comparison between the two cities on a typical summer day, two indices, PMV and Tmrt, were used. The results showed that the proposed new city design reduced Tmrt and PMV, contributing to improved thermal comfort. The proposed design reduced the Tmrt value in the model by 10.5°C in proportions of 90% of the total urban area. Furthermore, the suggested design offers superior thermal values on a typical summer day than Haifa Street.

This work was supported in part by the Spanish Government under Project PID2020-112545RB-C54 and, Project RTI2018-102002-A-I00, in part by “Junta de Andalucía” under Project B-TIC-402-UGR18, Project A-TIC- 608-UGR20, Project PYC20-RE-012-UGR and Project P18.RT.4830, and in part by the Predoctoral Grant FPU18/01965. (Corresponding author: Ángel Palomares-Caballero.), This paper presents a metal-only reflectarray that enables the control of incident orthogonal polarizations in a large bandwidth. The proposed reflectarray is based on a unit cell whose tuning elements allow the independent control of the reflection phase value for the vertical and horizontal impinging polarizations. Due to the symmetry of the unit cell, the same performance is produced by each polarization when its reflection phase response is modified. The proposed unit cell provides a fairly linear phase response along the frequency with a phase variation in the orthogonal polarization of ±1o. The performance under oblique incidence and the frequency limitation of the unit cell are also investigated. From this unit cell, a metal-only reflectarray that produces circular polarization from a linear polarization is designed. The reflectarray presents a simulated directivity greater than 27 dBi with an axial ratio below 1.5 dB from 32 GHz to 50 GHz (43.9% of bandwidth). A prototype is fabricated and the measured results agree well with the simulated ones. The obtained aperture efficiency is between 56% and 41% in the considered frequency band. The measured realized gain ranges from 27 dBi to 30.3 dBi where the achieved radiation efficiency is greater than 97%., Spanish Government PDC2022-133900-I00, PID2020-112545RB-C54, TED2021-129938B-I00, TED2021-131699B-I00, Junta de Andalucia B-TIC-402-UGR18, A-TIC-608-UGR20, PYC20-RE-012-UGR, P18.RT.4830, FPU18/01965

International audience

International audience; In coherent direction of arrival (DOA) estimation,subspace-based methods suffer from performance deteriorationbecause of the rank loss of the signal covariance matrix. Avariety of spatial smoothing preprocessing techniques have beenproposed for decorrelation, among which the enhanced spatialsmoothing preprocessing (ESS) technique shows outstandingperformance by exploiting the signal subspace. However, ESSis applied by squaring the matrix whose columns span thesignal subspace (called signal matrix), which involves unnecessarycomputational loads. Besides, the smoothed covariance matrixafter ESS is a linear combination of the sub-matrices of signalmatrix, where the coefficients of the combination may underminethe decorrelation performance. In this context, a simplifiedspatial smoothing (SSS) technique is proposed for decorrelationby averaging the sub-matrices of the signal matrix directly,and avoids redundant operations in squared signal matrix. Theproposed method is tested numerically in terms of the signal-to-noise ratio (SNR), the number of snapshots, angle separation,and the execution time. Simulation results show the improvementof the decorrelation performance, efficiency, and robustness withthe proposed method in coherent scenarios, compared with theother spatial smoothing preprocessing based methods.

We discuss the need for a confluence of localization, sensing and communications if RISs are to be deployed in a self-adaptive manner in the dynamically evolving rich-scattering settings that are typical for 6G deployment scenarios such as factories. We establish that in such problems the rich-scattering wireless channels are subject to a highly nonlinear deterministic double-parametrization through both the RIS and uncontrolled moving objects. Therefore, acquiring full context-awareness through localization and sensing is a prerequisite for RIS-empowered communications. Yet, the byproducts of this daunting communications overhead can feed many appliances that require context awareness, such that overhead concerns may vanish. We illustrate the essential steps for operating a self-adaptive RIS under rich scattering based on a prototypical case study. We discover that self-adaptive RISs outperform context-ignorant RISs only below a certain noise threshold that depends, among other factors, on how strongly uncontrolled perturbers impact the wireless channel. We also discuss ensuing future research directions that will determine the conditions under which RISs may serve as technological enabler of 6G networks., 7 pages, 5 figures, submitted to an IEEE Journal

International audience; Voluntary phantom movements are systematically associated with muscle contractions in the residual limb. These latter are specific to the type of movement and can be classified by pattern recognition algorithms. However, phantom mobility generates fatigue that could impact classification metrics. This study explored whether daily phantom movement training at home with no other feedback than inherent somatosensory information can impact the classification success rate. Kinematics and muscle activity were compared between before and after a two-month home training in six major upper limb amputees. Surface EMG patterns were classified to quantify a potential change in the features space with training. Our results showed that this type of training induces faster, smoother, and richer phantom mobility. However, classification metrics did not change with training. When including the new types of movements achievable after training, accuracy did not decrease, indicating that muscle activation patterns associated with these movements were sufficiently different not to interfere with the already existing movement classes. Thus, although phantom training with only somatosensory feedback increases the overall phantom movement capacity, it does not increase the classification success rate. Yet, it is possible that paired with other forms of feedback, phantom training could improve this success rate.

International audience; This paper introduces a procedure for multi-objective optimisation, for compact wideband superdirective antenna array design, using network characteristic modes. The two main objectives considered are the maximisation of the directivity in the end-fire direction, simultaneously with the minimisation of the input reflection coefficient in a large bandwidth. The proposed method is used thereafter for designing a three-element superdirective small Yagi antenna, with an overall dimensions of 0.4 lambda x 0.37 lambda x 0.18 lambda. The length of this mini yagi antenna is 60% shorter than a classical one, with the same performances of gain and bandwidth. The measured results show that the antenna bandwidth, maximum gain, and efficiency are of 11.2%, 8 dBi, and 95% respectively.

International audience; This work focuses on the impact of sulfonated Poly(Ether Ether Ketone) (sPEEK) membrane pretreatments on fuel cell performance, starting from two different batches of Fumapem E730 from Fumatech, acquired in 2019 and in 2020. sPEEK membranes are possible lower cost alternatives to PerFluoroSulfonic Acid (PFSA) membranes for Proton Exchange Membrane Fuel Cells (PEMFC) applications. Before use, they must be pretreated to ensure a complete protonic substitution and removal of residual reagents/solvent: the simplest protocol consists in soaking the membrane in an acid solution followed by a rinsing step in water. In addition to this acidification step, hydrothermal (HT) treatments in water at high temperature for a few hours to a few days were also considered herein, as well as a hydro-alcoholic (HA) step, because of their expected effects on membrane nanostructure. Overall, four different protocols were used. The membrane water uptake, water self-diffusion, proton conductivity, and fuel cell performance-under H2/O2-were measured. It was found that in the best case-membranes from the 2020 batch subjected to HA followed by 72 hours HT pretreatments-the fuel cell performances exceeded those obtained with a PFSA membrane (Nafion XL). This is explained by a higher protonic conductivity, probably resulting from a better sPEEK nano-structuration.

International audience; Reaching the corneal endothelium through the topical administration of therapeutic drugs remains a challenge in ophthalmology. Besides, endothelial cells are not able to regenerate, and diseases at this site can lead to corneal blindness. Targeting the corneal endothelium implies efficient penetration through the three corneal layers, which still remains difficult for small molecules. Carbon quantum dots (CQDs) have demonstrated great potential for ocular nanomedicine. This study focuses on the corneal penetration abilities of differently charged CQDs and their use as permeation enhancers for drugs. Excised whole bovine eyes were used as an ex vivo model to investigate corneal penetration of CQDs derived from glucosamine using β-alanine, ethylenediamine, or spermidine as a passivation agent. It was found that negatively charged CQDs have limited corneal penetration ability, while positively charged CQDs derived from glucosamine hydrochloride and spermidine (CQD-S) penetrate the entire corneal epithelium all the way down to the endothelium. CQD-S were shown to enhance the penetration of FITC-dextran 150 kDa, suggesting that they could be used as efficient penetration enhancers for therapeutic delivery to the corneal endothelium.

International audience

By collecting simultaneously optical and chemical/morphological data from nanoscale volumes, the Photonic Atom Probe (PAP) can be applied not only to the study of the relationship between optical and structural properties of quantum emitter but also to evaluate the influence of other factors, such as the presence of point defects, on the photoluminescence. Through the analysis of multiple layers of InGaN/GaN quantum dots (QDs), grown so that the density of structural defects is higher with increasing distance from the substrate, we establish that the light emission is higher in the regions exhibiting a higher presence of structural defects. While the presence of intrinsic point defects with non-radiative recombination properties remains elusive, our result is consistent with the fact that QD layers closer to the substrate behave as traps for non-radiative point defects. This result demonstrates the potential of the PAP as a technique for the study of the optical properties of defects in semiconductors.

International audience; The laser power bed fusion (L-PBF) additive manufacturing process is commonly used for fabrication of complex metal parts. To ensure the parts’ quality, monitoring of the manufacturing process by an instrument operating continuously during the manufacturing process should be carried out. The existing industrial solutions are limited in the sense that they are restricted to the detection of anomalies within machine state parameters or in the surface layers of the part under construction. Eddy current testing is a promising non-destructive testing method that could be applied for the layer-by-layer inspection of fused material during part fabrication. This inspection enables to follow the defects evaluation not only on the surface of the last fused layer but at the scale of the several fused layers. An eddy current sensor has been developed and adapted to perform measurements in a L-PBF machine during the manufacturing phase (in situ). The performance and potential of the technique in terms of robust integration in the machine and defects evaluation have been studied. The obtained results allowed to evaluate the detection limits according to the width and the height of the defects during the manufacturing of the part. The influence of the powder presence around the fused area has also been studied.

International audience; In this paper, a compact reconfigurable bandstop filter suitable for multistandard and multiband mobile terminals is reported. The proposed dual bandstop filter consists of a microstrip line coupled to two switchable Capacitively Loaded Loops (CLLs). We achieve the tuning of individual notched frequency bands by using open circuits as switches and incorporated in each CLL element. The performance characteristics in terms of S-parameters and surface currents distribution show that the proposed filter is able to adjust two stopbands independently in a wide tuning range. A corresponding prototype of tunable dual-stopband filter is manufactured, and practical measurements agree well with the simulation results.

International audience; In order to facilitate the development of wrist-worn vibrotactile devices, detailed knowledge about how vibrations are perceived by the users is needed. In particular, perceptual thresholds in amplitude are really important. Thresholds have been measured in the literature for other areas of the body, but given the variability reported between areas (shape of the threshold curve, position of maximum sensitivity), thresholds on the wrist can not be inferred from previous measurements and must be measured. The amplitude thresholds for vibrations normal to the skin surface were evaluated on 28 participants, with a three interval forced choice method. They were measured for 7 frequencies that are classical in the literature about vibrotactile perception (25, 40, 80, 160, 250, 320, and 640 Hz). The classical U-shape of the amplitude-threshold curve is observed, with a maximum sensitivity at around 160 Hz, which differs from other body areas, but confirms recent results obtained for vibrations parallel to the skin surface of the same body area. The sensitivity thresholds of vibrotactile signals appear to be in the micrometer range.

International audience; In this paper, a novel method to improve the readability of chipless tags is presented. When the EM wave falls upon the tag's surface at normal incidence or with a known incidence, the proposed approach permits to obtain a higher signal-to-noise ratio (SNR) of resonators whose orientation with respect to the normal to the plane in which the tag is positioned is unknown and thus, to increase the reading distance of the tag. It introduces a technique based on the detection of this tag orientation in relation to the antennas; a projection of the signals will allow to correct this misalignment in order to always be able to decode the tag identifier on a signal that corresponds to an ideal alignment between the tag and the antennas. With this principle, it is also possible to separate the resonance mode of the resonator that is connected to the identifier from other parasitic resonance modes that may appear due to a possible misalignment between the tag and the antenna. This principle is applied to loop resonators commonly used in chipless RFID which can present strong parasitic modes of resonance. Also, this method makes the reading orientation invariant, allowing to read the resonator whatever its orientation with respect to the normal to the plane in which the tag is positioned. Likewise, the proposed method can be also used to sense this resonator orientation. This method requires a dual-polarization antenna and a 2-ports vector network analyzer (VNA). Results are validated in simulation and with real-environment measurements for a single resonator as well as for multiple resonators, as it is classically used in the chipless RFID technology. Measurements in a harsh environment, as well as comparisons with classical techniques such as time gating, are presented. A study on the improvment of the read range is achieved to highligth the potential of the proposed technique. A reading distance of more than 80cm was thus obtained, which represents 20cm more than with the classic use of a post-processor based on time gatting. Finally, the principle of the measurement is generalized by applying it to a tag with a ground plane and considering that the antenna is not necessarily placed in normal incidence with respect to the plane of the tag.

International audience

International audience; In this paper, a new drivers’ warning application through personalized Direct-Sequence Spread Spectrum Code-Division Multiple Access (DSSS-CDMA) transmissions, performed using the FM radio broadcasting infrastructure is presented. The proposed application is designed to simultaneously transmit a maximum of 15 low-resolution image notifications together with standard FM radio broadcasting in different geographical areas. The application is intended to warn drivers of significant driving events in major traffic areas of a country. The proposed solution is low-cost and rapid to put into practice because the modifications, both on the transmission infrastructure and on the receiver’s side, are relatively easy to implement. The transmission of image notifications is performed in subsidiary bands of commercial FM radio systems. The receiver is implemented using the Software-Defined Radio (SDR) paradigm and is able to extract the audio signal (corresponding to the usual FM transmission) and the data component, depending on the geographical area in which the vehicle is located. The receiver is based on a novel implementation of a modified Costas loop using two new nonlinear limiters. Appropriate image notification is selected using a specific decoding key, generated according to the geographical position of the vehicle. The performance of the data transmission system is analyzed by plotting the Bit Error Rate (BER) versus the signal-to-noise ratio of the data signal for different numbers of image notifications simultaneously transmitted. The proposed radio communication system was validated through an experimental setup based on Universal Software Radio Peripheral (USRP) devices driven by MATLAB/Simulink software.

International audience; Background: The objective of this study was to demonstrate that synchrotron K-edge subtraction tomography (SKES-CT) can simultaneously track therapeutic cells and their encapsulating carrier, in vivo, in a rat model of focal brain injury using a dual-contrast agent approach. The second objective was to determine if SKES-CT could be used as a reference method for spectral photon counting tomography (SPCCT). Methods: Phantoms containing different concentrations of gold and iodine nanoparticles (AuNPS/INPs) were imaged with SKES-CT and SPCCT to assess their performances. A pre-clinical study was performed in rats with focal cerebral injury which intracerebrally received AuNPs-labelled therapeutic cells encapsulated in a INPs-labelled scaffold. Animals were imaged in vivo with SKES-CT and back-to-back with SPCCT. Results: SKES-CT revealed to be reliable for quantification of gold and iodine, whether alone or mixed. In the preclinical model, SKES-CT showed that AuNPs remained at the site of cell injection, while INPs expanded within and/or along the lesion border, suggesting dissociation of both components in the first days post-administration. Compared to SKES-CT, SPCCT was able to correctly locate gold, but not completely located iodine. When SKES-CT was used as reference, SPCCT gold quantification appeared very accurate both in vitro and in vivo. Iodine quantification by SPCCT was also quite accurate, albeit less so than for gold. Conclusion: We here provide the proof-of-concept that SKES-CT is a novel method of choice for performing dual-contrast agent imaging in the context of brain regenerative therapy. SKES-CT may also serve as ground truth for emerging technologies such as multicolour clinical SPCCT.

International audience; In this study, we quantify microscale heating at the level of cutaneous nerves and capillaries due to continuous and pulsed plane-wave exposure at 60 GHz. The thermal properties of the nerves and capillaries were derived using mixture equations based on their water content. The electromagnetic problem was solved in conjunction with Pennes bioheat equation and Arrhenius equation using finite element method to evaluate the spatial and temporal evolution of temperature along with thermal damage within cutaneous nerves and capillaries. Although, the maximum power density within the nerve (41.6 kW/m 3 ) and capillary (20 kW/m 3 ) was 37.3% and 30.2% higher than surrounding skin for a continuous exposure at 10 W/m 2 , the peak temperature elevation ( ΔT ) within the nerve (93.3 n°C) and capillary (90.7 n°C) occurred after 5 μ s and 10 μ s of exposure and was 19.2% and 17.7% higher than surrounding skin, respectively. The nerve and capillary attained thermal equilibrium with skin after roughly 10 ms. The maximal ΔT within the nerve (0.5 °C) and capillary (0.25 °C) due to nano- and micro-second 60 GHz pulses with highest fluence (0.48 kJ/m 2 ) permitted under ICNIRP guidelines was 34% and 24% higher than in the surrounding skin. Ten 3 μs 60 GHz pulses (power density = 13.4 GW/m 2 ) separated by 10 s of cooling period were used to demonstrate the possibility of selective thermal ablation of cutaneous nerves [damage index ( Ω )=1.1)] without damaging skin ( Ω = 0.15). The results provide valuable insights into local millimeter-wave induced heating within various skin substructures.

International audience; We provide a data-driven stabilization approach for input-saturated systems with formal Lyapunov guarantees. Through a generalized sector condition, we propose a convex design algorithm based on linear matrix inequalities for obtaining a regionally stabilizing datadriven static state-feedback gain. Regional, rather than global, properties allow us to address non-exponentially stable plants, thereby making our design broad in terms of applicability. Moreover, we discuss consistency issues and introduce practical tools to deal with measurement noise. Numerical simulations show the effectiveness of our approach and its sensitivity to the features of the dataset.

International audience; In this work we present the design and fabrication in metallic 3D-printing of a compact conformal slotted waveguide antenna array operating in the Ku-band. The application objective, although not limited only to this, is the optimisation of an antenna element which by stacking will be able to form a quasi-cylindrical sector. A beamforming network will be used for beam-steering in the elevation plane as coverage in the azimuthal plane is guaranteed by the conformal geometry. The compact design of the antenna element is therefore of great significance. For this reason, a direct feeding scheme by a coaxial connector is adopted. The antenna has been optimized following multiple parametric analyses of its geometrical parameters for the enhancement of the bandwidth, return losses and realized gain. The antenna was fabricated with Selective Laser Melting in aluminium and the experimental results agree well with the numerically calculated ones. The proposed CSWAA exhibits a reflection coefficient below -10 dB, realized gain above 14 dBi, as well as good cross-polarization and side-lobe level over a relative bandwidth of 8%.

Musculoskeletal simulations are useful in biomechanics to investigate the causes of movement disorder, to estimate non-measurable physiological quantities or to study the optimality of human movement. We introduce Bioptim, an easy-to-use Python framework for biomechanical optimal control, handling musculoskeletal models. Relying on algorithmic differentiation and the multiple shooting formulation, Bioptim interfaces nonlinear solvers to quickly provide dynamically consistent optimal solutions. The software is both computationally efficient (C++ core) and easily customizable, thanks to its Python interface. It allows to quickly define a variety of biomechanical problems such as motion tracking/prediction, muscle-driven simulations, parameters optimization, multiphase problems, etc. It is also intended for real-time applications such as moving horizon estimation and model predictive control. Six contrasting examples are presented, comprising various models, dynamics, objective functions and constraints. They include data-driven simulations (i.e., a multiphase muscle driven gait cycle and an upper-limb real-time moving horizon estimation of muscle forces) and predictive simulations (i.e., a muscle-driven pointing task, a twisting somersault with a quaternion-based model, a position controller using external forces, and a multiphase torque-driven maximum-height jump motion).

International audience; The hygrothermal behavior of a bio-based multilayered wall has been studied by numerical simulations. The key point of these research investigations was to properly describe the hygrothermal transfers occurring inside the studied wall solution. In previous work, the case of the wall subjected to a given real climate (Wroughton HIVE demonstrator, UK, Feb 2018) has been investigated. The present work, focused on the moisture regulation capacity of the wall, considers an improved kinetics model of sorption, different layer configurations, one additional climate (Bordeaux, FR, Apr 2008) and the effect of indoor cyclic loads. Compared to the classical approach, the local kinetics approach results in prediction of stronger and steeper hygric dynamics with larger relative humidity variations at small time scales. The study of the different wall configurations allows to determine the best one in terms of moisture damping: the vapor control membrane is advantageously removed provided the OSB3 12 mm layer is replaced by an OSB4 18 mm layer. Moreover, the simulations show that the Moisture Buffer Value characteristic of each material layer is not a sufficient criterion to evaluate hygric performance of the wall; strong hygric interactions occur with the layer's permeability independently of its sorption capacity. Finally, water content hysteresis phenomena are studied and it appears that under usual operating conditions, they can be ignored by adjusting the layers' permeabilities for adequate fits on the Moisture Buffer Value tests.

A compact asymmetric coplanar strip (ACS)-fed monopole antenna is presented, which operates within the Bluetooth and UWB frequency bands with the capability to simultaneously reject the lower WLAN interfering band. The antenna consists of an inverted right triangle patch monopole loaded by open-ended L-shaped slits not only to produce the additional 2.4 GHz passband to the UWB design but also to achieve stopband characteristics around 5.2 GHz. The conceptual equivalent circuit model as well as characteristic mode analyses are carried out in the design evolution process. The proposed antenna has an overall size of only 20 mm x 10 mm, having the smallest area among the so far developed designs, which can be easily integrated within any wireless gadgets. A prototype is fabricated and measured to validate the design, demonstrating the predicted behavior fairly achieved by full-wave analysis. The antenna -10 dB operating bandwidth ranges from 2.38 to 2.42 GHz and from 3.35 to 11 GHz while rejecting from 4.69 to 5.2 GHz. Unlike the unwanted stopband, where the radiation characteristics are adequately deteriorated, the proposed antenna fairly provides stable omni-directional radiation patterns in the H-plane, and has an average efficiency (gain) of 87.3% (2.6 dBi) in the desired passband. As far as the antenna transient behavior is concerned, an adequate measured (simulated) system fidelity factor of 0.7 (0.68) is achieved for the transmission of impulse-type UWB signals in the face-to-face configuration.

International audience; The electrification of vehicles is seen nowadays as a promising way to decarbonize the personal transportation. The assessment of environmental impacts of electric batteries is usually case-specific due to the complex modelling of such systems which present a large variability in designs, in user behavior or in geographic use conditions. A typical example is the battery lifespan which is arbitrarily chosen in most cases, even though it has a decisive influence on lifecycle emissions. Computing the battery lifespan in addition to a Life Cycle Assessment (LCA) would enable to highlight new hotspots and new parameters to reduce the environmental impacts of batteries. This paper introduces a new approach, based on a LCA conducted with the open-source software Brightway and built on primary data collected from a complete disassembly of a commercial electric vehicle. An original functional unit has been proposed that better represents the service offered by the battery over its lifetime and a semi-empirical ageing model has been integrated to predict more precisely the battery lifespan depending on design parameters and the use conditions. This innovative methodology is easily parameterized and aims to compare several eco-design strategies.