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Temperature-dependent electrostatic, linearity, and analog/RF performance of GaN HEMT
No full textInternational audienceTemperature has a major impact on the performance and reliability of high-frequency AlGaN/GaN HEMTs for high-power applications. Despite substantial research, these devices’ multi-bias behavior throughout a wide temperature range is still poorly understood. This study investigates DC, electrostatic, nonlinear, and analog/RF parameters from − 40 to 150 ℃ to fill this gap. The performance of GaN HEMT was evaluated by examining ON/OFF-state currents, subthreshold features, transconductance (gm), and its derivative, along with related parameters such as IMD3, 1-dB CP, and THD, which were evaluated together with RF performance indicators, including gain (Av) and gate-to-drain capacitance (Cgd). The transconductance generating factor (TGF), together with the product such as gain frequency (GFP), gain bandwidth (GBW), transconductance frequency (TFP), and gain transconductance frequency (GTFP), was also investigated. Among the electrostatic performance parameters, the currents in the ON state decreased, and the OFF state displayed an increasing trend as the temperature increased. The S-slope and S-swing, on the other hand, show a reverse trend with temperature. Both the current and the gm, along with its derivatives (gm2 and gm3), exhibit a declining trend as the temperature increases. The nonlinear performance of VIP2, VIP3, IIP3, 1-dB CP, IMD3, and THD, which rely on gm,is decreased with temperature. In terms of RF parameters, the Av, Cgd, ft, and fmax, as well as the TGF and GFP, are found to decrease with temperature. Meanwhile, the GBW, TFP, and GTFP all demonstrate an increasing trend with temperature. These findings provide valuable insights into the thermal impact on device parameters, which can be utilized to promote state-of-the-art technologies for the present and forthcoming deployments
ScenaSuite : plateforme numérique multisensorielle pour créer des activités interactives sans programmation
No full text36eme conférence International Francophone sur l'Interaction Humai-Machine, 3-7 novembre 2025, La cité-Toulouse (https://ihm2025.afihm.org/)International audienceScenaSuite is a digital platform that enables non-programmers to independently create interactive multisensory activities, referred to as "scenagrams." It was developed in response to needs identified in several research projects, particularly the limited accessibility of digital tools requiring programming or algorithmic skills. ScenaSuite features an intuitive, code-free interface and is built on a modular architecture comprising several components: ScenaConnect (for communication between connected objects), ScenaProd (the authoring software), and devices that can be integrated into scenagrams, including ScenaBox (a multisensory unit), ScenaMouv (a gesture sensor), and ScenaClick (a five-button arcade device). The platform is also compatible with third-party devices such as EZ-Robot’s JD robots and Ovaom tools. ScenaSuite supports the design of scenagrams for education, rehabilitation, or well-being by engaging multiple user senses. It aims to foster engagement, autonomy, and adaptability in therapeutic or educational contexts, while maintaining a human-centered approach.ScenaSuite est une plateforme numérique qui permet à des personnes non informaticiennes de créer de manière autonome des activités interactives multisensorielles, appelées scénagrammes. Elle a été conçue pour répondre aux besoins identifiés dans plusieurs projets de recherche, notamment la difficulté d’accès aux outils numériques nécessitant des compétences en algorithmique. ScenaSuite offre une interface intuitive sans programmation informatique et s’appuie sur une architecture modulaire intégrant plusieurs éléments : ScenaConnect (communication entre objets connectés, ScenaProd (logiciel de création) et des dispositifs pouvant être utilisés dans des scénagrammes : ScenaBox (boîtier multisensoriel), ScenaMouv (capteur gestuel) et, ScenaClick (5 boutons d’arcade). La plateforme est également compatible avec des objets tiers comme les robots JD d’EZ-Robotou les dispositifs Ovaom. Elle permet de concevoir des scénagrammes pour l’enseignement, la rééducation ou le bien-être, en sollicitant plusieurs sens de l’utilisateur. ScenaSuite vise à favoriser l’engagement, l’autonomie et l’adaptabilité en contexte thérapeutique ou éducatif, tout en restant centrée sur l’humain
Measurement of surface acoustic wave attenuation in aluminum using transverse acoustic field
No full textInternational audienceThis paper deals with the estimation of the attenuation of surface acoustic waves (SAWs). The proposed solution consists in measuring the displacement field transversely to the axis of propagation of the acoustic beam at several distances from the transducer, considering the entire field. Unlike measurements taken along the beam axis (the usual configuration), these transverse measurements avoid any positional error with respect to this axis. Furthermore, measurements in perpendicular planes integrate the beam's total energy, allowing divergence to be taken into account. Finally, as the measurement is carried out in the very near field (corresponding to the first tenth of the Fresnel zone), the SAW beam still has sufficient amplitude, enabling measurements to be made in a wider frequency range up to several tens of megahertz. The results of attenuation measurements on an aluminum sample at frequencies ranging from 10 to 50 MHz using the two approaches mentioned are reported, demonstrating the benefits of the proposed method in terms of measurement error
Impedance Control of Rehabilitation Exoskeletons based on Takagi-Sugeno Unknown Input Observer with Model Uncertainties
No full textInternational audienceThe paper presents the application of an unknown input observer for the specific needs of rehabilitation robotics. A nonlinear assist-as-needed control algorithm is presented, with the aim of meeting patient's needs in the best way. A Takagi-Sugeno fuzzy model is employed for the design of the unknown input observer whose objective is to estimate the model uncertainties expressed as an external disturbance. The simulation results demonstrate the efficacy of the proposed method and lay the foundation for future experimental developments
Synthesis of COF (TAPA-DHTA)-sodium alginate-Ca2+-polyacrylate composite microspheres as adsorbent for dispersive solid phase extraction of fluoroquinolone antibiotics in food and water prior to the quantification by HPLC-MS/MS
No full textInternational audienceThis work developed hydroxyl‑functionalized covalent organic framework (COF) via ambient-temperature synthesis and integrated it with sodium alginate-Ca²⁺-polyacrylate hydrogel to form composite microspheres (CACMPs) for dispersive solid-phase extraction (dSPE) of five fluoroquinolone antibiotics in milk , eggs and river water. Combining COF with hydrogel can effectively improve the hydrophilicity of adsorbent. The CACMPs do not require centrifugation and can be completely separated within one minute. After five cycles, they still maintain high extraction efficiency (>90 %). Coupled with HPLC-MS/MS, the method achieved a wide linear range (0.01–100 ng/mL), low detection limits (0.05–0.42 μg/kg), and high precision (RSD ≤20.5 %). Validation via spiked samples yielded recoveries of 80.3–117.3 %, confirming reliability for monitoring FQ residues in dairy. Design of CACMPs combines COF adsorption capacity with hydrogel practicality, offering a sustainable, efficient solution for antibiotic analysis in complex matrices
Electroluminescence and energy transfer mediated by hyperbolic polaritons
No full textData are publicly available on Zenodo at 10.5281/zenodo.10625437https://zenodo.org/records/14382617International audienceUnder high electrical current, some materials can emit electromagnetic radiation beyond incandescence. This phenomenon, referred to as electroluminescence, leads to the efficient emission of visible photons and is the basis of domestic lighting devices (for example, light-emitting diodes)1,2. In principle, electroluminescence can lead to mid-infrared emission of confined light–matter excitations called phonon polaritons3,4, resulting from the coupling of photons with crystal lattice vibrations (optical phonons). In particular, phonon polaritons arising in the van der Waals crystal hexagonal boron nitride (hBN) present hyperbolic dispersion, which enhances light–matter coupling5,6. For this reason, electroluminescence of hyperbolic phonon polaritons (HPhPs) has been proposed as an explanation for the peculiar radiative energy transfer within hBN-encapsulated graphene transistors7,8. However, as HPhPs are locally confined, they are inaccessible in the far field, and as such, any hint of electroluminescence has been based on indirect electronic signatures and has yet to be confirmed by direct observation. Here we demonstrate far-field mid-infrared (wavelength approximately 6.5 μm) electroluminescence of HPhPs excited by strongly biased high-mobility graphene within a van der Waals heterostructure, and we quantify the associated radiative energy transfer through the material. The presence of HPhPs is revealed by far-field mid-infrared spectroscopy owing to their elastic scattering at discontinuities in the heterostructure. The resulting radiative flux is quantified by mid-infrared pyrometry of the substrate receiving the energy. This radiative energy transfer is also shown to be reduced in hBN with nanoscale inhomogeneities, demonstrating the central role of the electromagnetic environment in this process
Trust-Based Shared Steering Control With Game Theory Using Event-Triggered ADP for Human-Vehicle Cooperative Driving
No full textInternational audienceThe trust level of drivers in automated driving systems (ADS) significantly impacts human-vehicle cooperation in terms of driving authority allocation and dynamic interactions during collaborative driving. However, trust dynamics for human-vehicle shared steering control (SSC) has rarely been researched. This paper presents a quantitative trust model and then proposes a trust-based cooperative driving strategy. Three contributions have been made in this paper: 1) An enhanced quantitative trust dynamics model is introduced, integrating real-time driving risk estimation and the deviation of driving operation expectations between human and vehicle; 2) A dynamic authority allocation strategy is proposed using fuzzy inference, providing real-time control authority based on trust and its changing rate; 3) A non-zero-sum (NZS) differential game framework is constructed, and an event-triggered adaptive dynamic programming (ET-ADP) method is adopted for Nash equilibrium control strategy derivation. The effectiveness and rationality are validated through high-fidelity Carsim-Simulink co-simulations and driver-in-the-loop (DIL) experiments, demonstrating the proposed model can achieve optimal control while reducing the driver operational workload and improving trust levels
Electronic and Thermoelectric Properties of Molecular Junctions Incorporating Organometallic Complexes: Implications for Thermoelectric Energy Conversion
No full textInternational audienceThe electronic and thermoelectric properties of molecular junctions formed from iron and ruthenium metal-acetylide were studied using complementary experimental techniques and quantum chemical simulations. We performed physical characterizations of single-molecule and self-assembled monolayer junctions of the same molecules that allowed meaningful comparisons between the Ru and Fe adducts. In the case of the Fe-containing junctions, two distinct oxidation states are present. These junctions exhibit one of the highest Seebeck coefficients (S ∼130 μV/K) reported to date for similar systems paired with broad electric conductance distribution and limited thermal conductance. As a result, the experimental thermoelectric figure of merit ZT for Fe-containing junctions reaches up to 0.4 for junctions with relatively high conductance. This is one of the highest ZT values reported for molecular systems at room temperature
Less-Conservative Robust Path Tracking Control With Intrinsic Bump-Free Feature for Autonomous Vehicles: A Sub-Polytope Integrated Approach
No full textInternational audienceThis paper proposes a novel sub-polytope integrated approach (sPIA) that features an intrinsic bump-free transition, aiming to reduce conservatism in the design of path tracking control for autonomous vehicles with large range time-varying longitudinal velocity. The approach encapsulates the interdependent time-varying parameters associated with longitudinal velocity as a set of finite-vertex sub-polytopes interconnected via junction points, thereby reducing the conservatism induced by modeling overbounding. The integration of junction points and the formulation of sub-region activation rules provide a theoretical foundation for avoiding abrupt changes in feedback gains, ensuring a bump-free transition between sub-regions. A gain-scheduling state feedback controller is designed, employing parameter-dependent Lyapunov functions to further attenuate design conservatism. The effectiveness of the proposed method in reducing design conservatism is demonstrated by a comparative analysis of the optimal H∞ performance indices across various sub-polytope integration schemes. Furthermore, the superiority of the method is exemplified via simulations within real-world driving scenarios, utilizing the high-fidelity CarSim-Simulink platform. The results indicate that the proposed sPIA outperforms traditional polytopic methods in path tracking performance. This improvement, together with the effective avoidance of bumps during sub-regional transitions, confirms the efficacy of the proposed approach. Moreover, the real-time performance of the method is verified by hardware-in-the-loop experiments
Telerehabilitation in the remote care of patients’ postorthopaedic surgery: benefits and limitations for patients
No full textInternational audienceObjective: The aim of this study was to identifythe factors that might influence patients' adoption of telerehabilitation post orthopaedic surgery knee and hip. Method: Semi-structured interviews were conducted with 20 THA (n=6), TKA (n=14) patients. These interviews were guided by an interview framework inspired by the Unified theory of acceptance and use of technology 2 (UTAUT2). The System Usability Scale (SUS) was used to assess patients’ perception of usability. Results: The interviews highlighted facilitators perceived by the subjects, such as reinforcement and motivation to practice physical activity, personalized follow-up from clinicians (via gamification), complementarity to conventional therapy and cost (urban travel). The results also revealed perceived barriers, including the risk of injury and lack of relationship with the professional. These factors need to be considered in user-centered design. SUS results were not influenced by the subject gender, or age. The results obtained for the SUS indicate an average score of 54.6 ± 19.6, meaning that potential usability is slightly acceptable. Conclusion: User-centred design is essential for adherence. Individualised and gamified programmes could improve patient care by encouraging participation and autonomy. Setting achievable goals and clinician support help maintain engagement, ensuring the long-term benefits of exercise. These key points could increase mass participation and thus improve tele-rehabilitation care