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Estimation of Variable Optical Feedback Coupling Factor for Self Mixing Interferometry by Signal to Image Translation
No full textInternational audienceAccurate estimation of the optical feedback coupling factor C is essential for the reliable operation of laser-based self-mixing interferometry (SMI) sensors, particularly in variable feedback conditions. In this work, we present a novel deep learning-based method to estimate the time-varying C factor from SMI signals under strong, moderate, and weak feedback conditions. The proposed approach leverages a transformation of one-dimensional (1D) SMI signals into two-dimensional (2D) image representations, allowing convolutional neural networks to extract context-rich features that enhance estimation performance. Unlike traditional image processing tasks, this method formulates the problem as a signal-to-image translation, tailored for sensor parameter inference. Experimental results demonstrate that this 2D-based approach outperforms state-of-the-art recurrent neural network models, including LSTM and transformer architectures, particularly in terms of robustness to changes in sampling frequency, displacement amplitude, and feedback regime. The methodology is generic and applicable to a wide range of sensor signal analysis tasks. To support reproducibility and practical adoption, we provide a publicly available implementation of our approach
B-Variational Autoencoder based Anomaly Detection in Log Data - Application to radiotherapy systems
No full textDirectional light scattering in Mie-resonant Si particles with ultra-thin plasmonic shells
No full textInternational audienceWe present the synthesis and characterization of Au-decorated Si core-shells as candidate meta-atoms. We found a damped magnetic dipole (MD) for smaller Si cores (100 – 130 nm) and an enhanced MD for larger cores (150 – 200 nm). Continuous plasmonic shells of ~12 nm are needed to significantly improve forward scattering.Subwavelength-sized Si particles interact strongly with visible (vis) and near-infrared (NIR) light to produce strong electric and magnetic resonances. These can combine to produce interesting optical effects, such as pure forward scattering. A requirement for this to occur efficiently is that the electric dipole (ED) and magnetic dipole (MD) modes must be of similar amplitude and phase. At wavelengths where this occurs, the particles act analogously to the forward-propagating point sources of light used in Huygens’ constructions. This directional scattered light has a range of potential applications in the creation of metamaterials.We have investigated dielectric@metal core-shell architectures comprised of both resonant cores and resonant shells as candidate particles in which the spectral overlap of the electric and magnetic dipoles might be controlled to create strong directional scattering. There are currently two reports of the synthesis and characterization of Au shells around Si cores, both thicker than desirable. [1,2] Chaâbani et al. presented Si@Au particles, with non-uniform shells composed of Au particle diameters between 10 and 25 nm, which presented enhanced electric field and Fano-resonances due to the coupling of the Mie modes of the Si core and the localized surface plasmon resonance (LSPR) of the Au shell. [1] Sugimoto et al. similarly presented Si@Au particles with a rough ~25 nm Au shell. [2] In both of these reports of Si@Au core-shell particles, the experimental data could not be accurately fit by simulations due to non-spherical cores and inhomogeneous shells. Ultrathin and homogeneous coatings have not yet been achieved around spherical Si particles.In this study, we present a two-step aqueous approach to prepare Si@Au core-shell particles with controllable shell thickness below 10 nm. The Au nanoparticle (AuNP) density around the Si particles can be increased by performing a second functionalization/deposition step. We studied the electromagnetic response of the particles using single-particle scatter spectroscopy and electron energy loss spectroscopy (EELS). Our results were compared with reference Si spheres and SiO2@Au core-shell particles, to allow us to establish the contribution from the Au decoration to the optical response of the hybrid particles. To further elucidate the nature of the electromagnetic response of the particles, these observations were supported by T-matrix simulations which replicated our experimental findings, and showed the importance of controlling the shell/core dimensions and the need for a continuous shell to maximize forward scattering. We found that continuous plasmonic shells of ~12 nm thickness are needed to significantly improve forward scattering intensity.References1.Chaâbani, W, J Proust, S Ouellet, A Movsesyan, J Béal, R Bachelot, T Xu, A L Baudrion, PA Adam, D Boudreau, A Chehaidar, and J Plain, “Si@Au core–shell nanostructures: Toward a new platform for controlling optical properties at the nanoscale.” J Phys Chem C, Vol. 125, 20606. 2021. DOI: 10.1021/acs.jpcc.1c061822.Sugimoto, H., T Hinamoto, Y Kazuoka, A Assadillayev, S Raza, and M Fujii. “Mode hybridization in silicon core–gold shell nanosphere.” Small Vol. 18, 2204890, 2022. DOI: 10.1002/smll.20220489
Improving Near-Field Probe Calibration Technique for Immunity Tests at PCB Level
No full textInternational audienceNear-field scan immunity (NFSI) enables localised and controlled field injection, making it a powerful technique for assessing the vulnerability of electronic components to radio frequency directed energy weapons (RF DEW). However, the lack of rigorous probe calibration methods currently limits its use to qualitative analysis. This paper introduces a complete calibration workflow for electric and magnetic near-field (NF) injection probes, based on the equivalent dipole assumption. The method quantifies both the main and parasitic field components and establishes the spatial and frequency range over which the dipole model remains valid. This characterisation enables the quantitative prediction of field-to-line coupling, through simulation or analytical models, when the properties of the trace and the component impedance are known. The proposed approach provides a necessary foundation for making NFSI a quantitative tool for immunity analysis. Experimental validations on various probes and PCB traces support the methodology and demonstrate its practical relevance
Towards IoT-based Smart Mobility Frameworkfor Proactive Road Stress Detection inIndividuals with ASD
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Vers une approche collaborative pour l'orchestration de services dans les réseaux multi-domaines interalliés
No full textNational audienceNetwork softwarisation has reshaped the design and operation of modern communication systems and how communication services are managed, from fulfilment, control and quality assurance to decommissioning. Service orchestration is now a reality in the context of a network under one single administrative authority. However, it faces many challenges when it comes to multi-administrative multi-domain networks, as domains restrict the information and collaboration capabilities they disclose to other domains. This is especially the case of military coalition networks, where ally nations connect and share some of their network infrastructure to support the communications services required by military missions. This work investigates the opportunities brought by network softwarisation to enable end-to-end service orchestration and devise novel end-to-end services for future federated military networks. The following contributions are proposed in this thesis. A flexible domain-level computing and network resource abstraction framework is defined. Compared to existing abstractions, it enables an enriched collaboration between domains while respecting their respective confidentiality constraints. Two novel end-to-end multi-domain service models are also proposed and prototyped on a physical network platform. Their corresponding resource embedding methods, which compute the optimal placement of their components with respect to network resource utilisation, are defined and then extensively evaluated.La softwarisation des réseaux a transformé la conception et l'exploitation des systèmes de communication modernes, ainsi que la gestion des services de communication, allant de leur mise en œuvre, leur contrôle, et assurant leur qualité jusqu'à leur décommissionnement. Dans le cadre d'un réseau placé sous une seule autorité administrative, l'orchestration des services est désormais une réalité. Cependant, elle fait face à de nombreux défis lorsqu'il s'agit de réseaux multi-domaines et multi-administratifs, où chaque domaine restreint les informations et les capacités de collaboration qu'il divulgue aux autres domaines. Cela est particulièrement vrai pour les réseaux de coalition militaire, dans lesquels des nations alliées connectent et partagent une partie de leur infrastructure afin de soutenir les services de communication nécessaires au bon déroulement de missions. Ce travail explore les opportunités offertes par la softwarisation des réseaux pour permettre l'orchestration de services de bout en bout et en concevoir de nouveaux. Les contributions suivantes sont proposées dans cette thèse : un cadre d'abstraction flexible pour les ressources réseau et informatiques au niveau du domaine est défini. Comparé aux abstractions existantes, ce cadre permet une collaboration enrichie entre les domaines tout en respectant leurs contraintes de confidentialité respectives. Deux nouveaux modèles de service multi-domaines de bout en bout sont également proposés et prototypés sur une plateforme réseau physique. Les méthodes d'intégration des ressources correspondantes, qui calculent le placement optimal de leurs composants en fonction de l'utilisation des ressources réseau, sont définies et évaluées de manière approfondie
Efficient Computation of Laser Self-Mixing Sensor Signal under Variable Optical Feedback
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Cascaded Voltage-Current Control for Grid-Forming Inverters: Design of Multi-Resonant State-Feedback Controller Using LMI Approach
No full textInternational audienceGrid-forming (GFM) inverters play a critical role in regulating voltage and frequency to ensure stable operation of isolated microgrids. Among the various control strategies, resonant controllers are recognized as one of the highestperformance solutions for AC current and voltage control. Traditionally, state feedback control implementations based on single loop control have been widely used for GFM inverters. However, these structures exhibit limitations in addressing key issues such as current reference tracking, and overcurrent conditions. To overcome these challenges, this paper proposes a discrete state feedback proportional multi-resonant control strategy implemented within a cascaded voltage-current loop for GFM inverters. This approach enables the controller to handle both current and voltage reference tracking simultaneously. A set of linear matrix inequality (LMI) constraints is employed to synthesize controller gains ensuring robust stability. Simulation results demonstrate the effectiveness of the proposed control strategy in achieving harmonic mitigation and precise reference tracking
Direct Numerical Simulation of an aluminum particle combustion in oxidizing flow, with gas and condensed-phase reactions
No full textInternational audienceAluminum (Al) particles are promising fuels for propulsion and energy conversion, sparking decades of research into their combustion. When micron-sized aluminum burns in an oxidizing environment, the process unfolds in two stages: an initial steady, symmetric vapor-phase combustion, followed by unsteady, asymmetric combustion as alumina decomposes, releasing gaseous sub-oxides. These sub-oxides condense and dissolve in the liquid droplet, forming liquid aluminum oxide. However, the multiphase mechanisms and reactions driving this transition remain poorly understood, which undermines the accuracy of the combustion model. To address this, a 3-dimensional Direct Numerical Simulation (DNS) approach based on Navier-Stokes equations is used to model single-particle Al combustion in air. Finally, this model underscores three critical aspects: (1) the development of an accurate and robust numerical framework to elucidate the complex physiochemical processes governing aluminum combustion, (2) detailed quantification of the role of sub-oxides condensation on the burning droplet and its subsequent influence on heterogeneous surface reactions and aluminum vaporization dynamics, and (3) an evaluation of existing vaporization laws (burn rates), contributing valuable insights for macroscopic combustion model refinement
Formal approach for Evolutionary Microgrids Modeling and Simulation
No full textInternational audienceThe evolution of microgrids over time may lead to changes in its models that involve several disciplines like electrical engineering, control systems, and optimization. These models need to be updated regularly whenever there is a change in the composition of the system, as changes in the system's composition directly affect the governing equations of power flow and network dynamics. However, some traditional approaches lack a formal framework to update automatically the models that reflect these composition changes, mainly when considering complex systems integrating several modeling paradigms. To tackle with this, we propose a formal approach based on graph and DEVS formalism that will enable rigorous representation of microgrid behavior and its dynamic structural evolution. Our approach ensures that system equations are automatically updated as the microgrid composition evolves, allowing for more accurate, scalable, and flexible simulations. We validate the efficiency and applicability of our approach through its implementation in Power Flow Analysis (PFA), demonstrating its capability to handle dynamic structure systems across multiple domains