HAL-INSA Toulouse
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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
Étalonnage des sondes magnétiques pour l'étude de la susceptibilité électromagnétique en champ proche
No full textNational audienceLe scan d'immunité en champ proche (NFSI, Near-field scan immunity) permet une injection très localisée pour évaluer la susceptibilité électromagnétique (EM) des composants électroniques, mais sa précision repose sur un étalonnage minutieux des sondes. Cet article propose une amélioration du modèle de dipôle équivalent pour les sondes magnétiques. La méthode proposée évalue et quantifie les limites spatiales et fréquentielles de l'approximation par dipôle tout en examinant les composantes dominantes et parasites du champ produit
Quasiparticle band picture bridging topology and strong correlations across energy scales
No full textUnderstanding the interplay between electronic correlations and band topology remains a central challenge in condensed matter physics, primarily hindered by a language mismatch problem. While band topology is naturally formulated within a single-particle band theory, strong correlations typically elude such an effective one-body description. In this work, we bridge this gap leveraging the ghost Gutzwiller (gGut) variational embedding framework, which introduces auxiliary quasiparticle degrees of freedom to recover an effective band structure description of strongly correlated systems. This approach enables an interpretable and computationally efficient treatment of correlated topological phases, resulting in energy- and momentum-resolved topological features that are directly comparable with experimental spectra. We exemplify the advantages of this framework through a detailed study of the interacting Bernevig-Hughes-Zhang model. Not only does the gGut description reproduce established results, but it also reveals previously inaccessible aspects: most notably, the emergence of topologically nontrivial Hubbard bands hosting their own edge states, as well as possible ways to manipulate these through a finite magnetization. These results position the gGut framework as a promising tool for the predictive modeling of correlated topological materials
Reversible Photocyclization of imidazoleisoindole-based stilbene derivatives apparently over non-triene form
No full textInternational audienceDiarylethene is one of the most extensively studied photochromic compounds due to its remarkable properties. Recently, nitrogen‐based diarylethenes (DAEs) have been reported to exhibit unusual photochromic behavior. In this study, we synthesized an imidazoleisoindole‐based stilbene analogue, which involves a neutral C═C─C═C─C─N framework, along with a C═C─C═C─C═N form as a minor mesomeric form. Crystal structural analysis supported the major contribution of the former form. Surprisingly, the molecule exhibited not only E–Z photoisomerization but also the photocyclization reaction with a quantum yield of 0.3. The orbital symmetry of the HOMO and LUMO around the reactive center closely resembled to that of typical DAEs and satisfied the Woodward–Hoffmann rules. Imidazolium analogue is also studied for comparison. The imidazoleisoindole‐based stilbene analogue represents a novel and unusual example of photocyclization in DAEs, uncovering the importance of the symmetric feature of LUMO and HOMO around the reactive center for the photocyclization
This work was supported by Prociencia-Concytec, Perú, under project "Manufactura de Estaciones de Recarga DC Bidireccionales de Vehículos Eléctricos, de alta durabilidad y eficiencia para aplicaciones "Vehicle to Grid" and "Vehicle to Home" en condiciones de funcionamiento de carga equilibradas y/o desequilibradas" under Grant PE501082509-2023. An earlier version of this paper was presented in part at 2023 IEEE Energy Conversion Congress and Exposition (ECCE) [
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Mass transport driving forces under electric current in the liquid Sn-Zn system
No full textInternational audienceSignificant effects of electric currents on mass transport in liquid metals have been observed for long, but the origin of the corresponding driving forces remains unclear in the literature. Without current, two driving forces induce mass transport in liquid metals. (i) A chemical force, coming from concentration gradients. In that case, mass transport occurs by diffusion. (ii) A physical force, resulting from density gradients thermally and/or chemically induced. Here, mass transport occurs by thermal and/or solutal convection. Under electric currents, these driving forces are modified, either by electrostatic or magnetic forces, the corresponding mechanisms being referred to as electroconvection and magnetoconvection, respectively. However, these mechanisms cannot easily be distinguished from each other, leading to confusion in literature. Here, it has been shown that, in the liquid Sn-Zn system, the driving force induced by 500-1000 A/cm 2 electric current densities is magnetic rather than electrostatic, the mechanism being therefore magnetoconvection.</div
Analysis and stabilization of a model of population dynamics with age structure and diffusion
No full textInternational audienceWe analyze a system modeling the evolution of an age and spatially structured population (of Lotka-McKendrick type). We study it by first writing it in an abstract form using several operators. We show that the semigroup associated with the corresponding system is differentiable. Using this property, we show how to prove the exponential stabilization with a finite-dimensional feedback control. We consider two types of controls: one that acts directly on the main equation of evolution and one that acts on the birth equation. One of the main difficulties in the analysis of this system is that the operators involved in the system can depend on the age variable. We use in particular a parabolic evolution operator associated with the main operator of the system. Our stabilization result shows how to extend the framework associated with parabolic system to the case of differentiable semigroups
RNA stability is regulated by both RNA polyadenylation and ATP levels, linking RNA and energy metabolisms in Escherichia coli
No full textInternational audienceThe post-transcriptional process of RNA polyadenylation sits at the crossroads of energy metabolism and RNA metabolism. RNA polyadenylation is catalyzed by poly(A) polymerases which use ATP as a substrate to add adenine to the 3’-end of RNAs, which can alter their stability. In E. coli, RNA polyadenylation mediated by the major poly(A) polymerase was previously shown to facilitate degradation of individual RNAs. In this study, we performed the first genome-wide study of RNA stability in the absence of PAP I. Inactivation of the pcnB gene coding for PAP I led to the stabilization of more than a thousand of E. coli RNAs in the form of full-length functional molecules or non-functional fragments. The absence of PAP I altered the energy metabolism, with an almost 20% reduction in ATP levels. To better understand how RNA and energy metabolisms are interconnected, we investigated the role of ATP levels in regulating RNA stability. When we lowered intracellular ATP levels below 0.5mM, many RNAs were stabilized demonstrating the causal link between ATP levels and RNA stability for the first time in E. coli. Above this concentration, changes in ATP levels had no impact on RNA stability. We also demonstrated that some RNAs were stabilized when PAP I was inactivated by low ATP availability. These results clearly demonstrate that PAP I mediates an energy-dependent RNA stabilization which may contribute to cell energy homeostasis under energy-limited conditions
Bose-Einstein condensate source on a optical grating-based atom chip for quantumsensor applications
No full textInternational audienceWe report the preparation of Bose-Einstein condensates (BECs) by integrating laser cooling with a grating magneto-optical trap (GMOT) and forced evaporation in a magnetic trap on a single chip. This new approach allowed us to produce a atom Bose-Einstein condensate of rubidium-87 atoms with a single laser cooling beam. Our results represent a significant advance in the robustness and reliability of cold atom-based inertial sensors, especially for applications in demanding field environments
Renormalised energy between boundary vortices in thin-film micromagnetics with Dzyaloshinskii-Moriya interaction
No full textInternational audienceWe consider a three-dimensional micromagnetic model with Dzyaloshinskii-Moriya interaction in a thin-film regime for boundary vortices. In this regime, we prove a dimension reduction result: the nonlocal three-dimensional model reduces to a local two-dimensional Ginzburg-Landau type model in terms of the averaged magnetization in the thickness of the film. This reduced model captures the interaction between boundary vortices (so-called renormalised energy), that we determine by a Γ-convergence result at the second order and then we analyse its minimisers. They nucleate two boundary vortices whose position depends on the Dzyaloshinskii-Moriya interaction