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PowerSecBench: reveal microarchitectural power leakages using generic RISC-V microbenchmarks
No full textInternational audiencePower side-channel attacks exploit variations in power consumption to recover sensitive information. To design secure systems, we must consider all the leakage sources to ensure that attackers cannot exploit any weakness. However, they can greatly vary between different processor microarchitectures and their internal mechanisms. Particularly, with the growing interest in the open-source RISC-V ISA and its numerous implementations, generic tools and strategies become essential to finely evaluate the security offered by each system.In this paper we present PowerSecBench, a software environment to evaluate power leakages on RISC-V processors. Starting from a range of various in-order implementations, from single-cycle to superscalar designs, we show how PowerSecBench allows characterizing leakages in each of them considering both value-and transition-based leakages. It uses a set of configurable microbenchmarks to test the different microarchitectural features. By simply executing them on both simulated and real FPGA targets, it becomes possible to identify most of the hardware sources, as well as consider physical parameters. Finally, we show that PowerSecBench can also be used to study the impact and limitations of protection strategies, such as pure software fences
Fonctionnalisation de joints collés pour contrôler le démantèlement à la demande de structures composites aéronautiques
No full textInternational audienceIn the context of enhancing the sustainability of aerospace vehicles, the structures must be designed to anticipate the possibility of disassembly. Mandatory certification in aeronautics and the robustness of satellites require structures to maintain their integrity to ensure safety during their life, which can come into conflict with the need for disassembling or demising. This is particularly the case for composite structures assembled though adhesive bonding. In this paper, a controlled disassembly device of the substrates of a component for keeping their integrity and surface states after debonding is proposed. The addition of thermally expandable particles (TEPs) and a metallic grid is investigated in various proportions, substrates, and adhesives. It is shown that the introduction of the disassembling system into a 100 µm adhesive bonding does not significantly affect the strength of the joint during life. Disassembly only happens when and if desired at a load level above the natural mode I and mode II ruptures of the assembly. The proposed solution helps to make functionalization of the bonded joint a good way to address sustainability regarding the preservation of resources, transforming the adhesive joint into a structural functional material
Analyse comparative par diffraction électronique de la relaxation de la déformation dans les matériaux AlxGa1-xN dans l'industrie microélectronique : Approche 4D-STEM vs. solution N-PED basée sur TEM
No full textInternational audienceOwing to its high spatial resolution and its high sensitivity to chemical element detection, transmission electron microscopy (TEM) technique enables to address high-level materials characterization of advanced technologies in the microelectronics field. TEM instruments fitted with various techniques are wellsuited for assessing the local structural and chemical order of specific details. Among these techniques, 4D-STEM is suitable to estimate the strain distribution of a large field of view. This study tends to discuss the viability of using two existing commercial solutions with a low-convergence angle 4D-STEM technique and TEM-based Nanobeam Precession Electron Diffraction (N-PED) methods for strain analysis in an industrial context. In such a framework, strain measurements intend to point out the extent of defects and thus reveal a trend of the stress field, rather than to precisely estimate the absolute values of the deformations. Strain distribution maps have been obtained for AlGaN/GaN HEMT devices using two transmission electron diffraction analysis methods. The performances of 4D-STEM and Nanobeam Precession Electron Diffraction (N-PED) solution for strain mapping have been compared for both a relatively thin (≈ 55 nm) and a thick (≈ 150 nm) TEM cross section specimen. The strain maps obtained with both methods have shown comparable results for a thin sample, with the ability to characterize the deformation induced by a 1 nm-thick layer of AlN spacer grown between the AlGaN barrier and GaN channel forming the 2DEG of the HEMT device. The results presented here also illustrate the limitation of both commercial solutions in the case of a thick sample.</div
Phase control of transmission and reflection in a sample of duplicated two-level systems driven by a stationary control field
No full textInternational audienceIn this article, we study the optical response of a duplicated two-level atomic medium subjected to a stationary control field and a weak co-propagating probe field, orthogonally polarized to each other. We show that both the reflected and transmitted components of the probe can be absorbed or amplified. Furthermore, for moderate optical depths, the reflection and transmission factors are controlled by the relative phase between the control and probe fields, making the configuration we present here promising for the development of optical devices. We also determine the exact conditions under which reflection and transmission factors can be controlled by the relative phase between the control and probe fields
Fabrication et caractérisation de diodes Schottky 1 kV avec protection par plaque de champ en Al2O3 /Si3N4
No full textInternational audienceDans un contexte d’électrification des systèmes, l’optimisation des composants électroniques est primordiale pour réduire la consommation énergétique. Parmi les matériaux à large bande interdite étudiés pour remplacer le silicium, le diamant se distingue comme un candidat prometteur pour des applications de haute puissance.Actuellement, la diode Schottky constitue le dispositif en diamant le plus étudié et démontre des résultats encourageants. Toutefois, des améliorations demeurent nécessaires pour accroître la tension de claquage. L’absence de terminaison de jonction efficace provoque notamment une concentration du champ électrique en périphérie du composant, entraînant un claquage électrique prématuré et limitant ainsi les performances théoriques du diamant.La solution de protection périphérique par plaque de champ (Field Plate, FP) est couramment utilisée pour protéger le contact Schottky et réduire le champ électrique au bord du composant. Cependant, de nombreux designs de FP présentent un claquage prématuré du diélectrique en raison de l’utilisation de matériaux à faible permittivité. Pour y remédier, nous proposons un design de FP basé sur un empilement Al₂O₃/Si₃N₄ (20/200 nm), présentant des permittivités élevées. La qualité de l’empilement a été préalablement étudiée par des mesures C-V sur silicium.Le processus de fabrication des diodes sera présenté. La tension de claquage sera évaluée par des mesures I-V réalisées dans un environnement sous vide entre 300 K et 850 K. De plus, la nature et la densité des pièges dans les diélectriques, susceptibles de dégrader les performances des diodes, seront analysées par des mesures C-V sur des capacités MIS (Métal-Isolant-Semi-conducteur), intégrées au même échantillon diamant
contributions à l’optimisation de la conception multidisciplinaire sousincertitude, avec des applications à la conception des avions
No full textThis thesis addresses multidisciplinary design optimization under uncertainty (U-MDO), a useful approach in modern engineering for optimizing complex systems like aircraft. Unlike traditional methods, U-MDO integrates multiple disciplines to optimize overall performance while accounting for uncertainties from simplified assumptions or stochastic factors.Methodological Contributions:- Scalable Problem for U-MDO Algorithm Testing: A theoretical framework was developed to benchmark U-MDO algorithms.- Generic Transformation for Multidisciplinary Problems: A method to transform standard optimization problems into multidisciplinary ones was proposed, modeling objective and constraint functions to reflect disciplinary interactions.- New Bi-Level U-MDO Formulation: Inspired by industrial needs, an approach using random sub-optimizations was developed, enabling the reuse of existing disciplinary optimization processes.- Enhancements to GEMSEO Library: Tools were integrated to solve U-MDO problems, facilitating robust optimization in industrial settings.Applicative Results:The methodology was tested on two practical cases:- A supersonic business jet.- A re-engineering study using a generic research aircraft configuration.These contributions enhance the ability to manage uncertainties in complex systems while reducing costs and improving reliability.Cette thèse se concentre sur l'optimisation multidisciplinaire sous incertitude (U-MDO), un domaine important dans la conception d’ingénierie moderne, en particulier pour des systèmes complexes comme les avions. Contrairement aux méthodes traditionnelles, l’U-MDO intègre simultanément plusieurs disciplines pour optimiser la performance globale tout en tenant compte des incertitudes dues à des hypothèses simplifiées ou des facteurs stochastiques.Contributions méthodologiques :- Problème dimensionnable pour évaluer les algorithmes U-MDO : Un problème "scalable" a été développé pour tester les algorithmes U-MDO.- Transformation générique pour les problèmes multidisciplinaires : Une méthode pour convertir des problèmes d’optimisation standard en problèmes multidisciplinaires a été proposée, en modélisant les fonctions d'objectif et de contrainte pour refléter les interactions disciplinaires.- Nouvelle formulation bi-niveau U-MDO : Inspirée des besoins industriels, une approche intégrant des sous-optimisations aléatoires a été développée, permettant de réutiliser les processus d’optimisation disciplinaire existants.- Améliorations de la bibliothèque Python GEMSEO : Intégration d'outils pour résoudre les problèmes U-MDO, facilitant ainsi l'optimisation robuste dans des contextes industriels.Résultats applicatifs :La méthodologie a été testée sur deux cas pratiques :- Un jet supersonique d’affaires.- Une étude de réingénierie à l'aide d'une configuration générique d'avion de recherche.Ces contributions renforcent la capacité à gérer les incertitudes dans les systèmes complexes tout en réduisant les coûts et en améliorant la fiabilité
Active charge and discharge of a capacitor: Scaling solution and energy optimization
No full textInternational audienceWe study—both theoretically and experimentally—charging and discharging capacitors that are actively controlled using a voltage source. We show how an appropriate choice of control voltage allows the charging or discharging to take place very slowly (quasistatically). Conversely, we study the price to be paid in terms of Joule heat when we speed up these processes. Finally, we develop optimal processes that minimize energy consumption for a finite charging time. Our study combines fundamental concepts in thermodynamics, classical mechanics, and electrical circuits. This topic lends itself well to an experimental project in the classroom, involving computer control of a voltage source, data acquisition, and processing
Observing Spatial Charge and Spin Correlations in a Strongly-Interacting Fermi Gas
No full text13 pages, 11 figuresTwo-dimensional correlated fermions constitute a cornerstone of quantum matter, covering a broad fundamental and technological scope, and have attracted increasing interest with the emergence of modern materials such as high- superconductors, graphene, topological insulators, and Moir\'e structures. Atom-based quantum simulators provide a new pathway to understand the microscopic mechanisms occurring at the heart of such systems. In this work, we explore two-dimensional attractive Fermi gases at the microscopic level by probing spatial charge and spin correlations in situ. Using atom-resolved continuum quantum gas microscopy, we directly observe fermion pairing and study the evolution of two- and three-point correlation functions as inter-spin attraction is increased. The precision of our measurement allows us to reveal a marked dip in the pair correlation function, fundamentally forbidden by the mean-field result based on Bardeen-Cooper-Schrieffer (BCS) theory but whose existence we confirm in exact auxiliary-field quantum Monte Carlo calculations. We demonstrate that the BCS prediction is critically deficient not only in the superfluid crossover regime but also deep in the weakly attractive side. Guided by our measurements, we find a remarkable relation between two- and three-point correlations that establishes the dominant role of pair-correlations. Finally, leveraging local single-pair losses, we independently characterize the short-range behavior of pair correlations, via the measurement of Tan's Contact, and find excellent agreement with numerical predictions. Our measurements provide an unprecedented microscopic view into two-dimensional Fermi gases and constitute a paradigm shift for future studies of strongly-correlated fermionic matter in the continuum
A physical noise model for quantum measurements
No full textInternational audienceIn this paper we introduce a novel noise model for quantum measurements motivated by an indirect measurement scheme with faulty preparation. Averaging over random dynamics governing the interaction between the quantum system and a probe, a natural, physical noise model emerges. We compare it to existing noise models (uniform and depolarizing) in the framework of incompatibility robustness. We observe that our model allows for larger compatibility regions for specific classes of measurements
Selective laser melting of partially amorphous regolith analog for ISRU lunar applications
No full textInternational audienceAs the idea of crewed outposts on the Moon gains momentum, In-Situ Resource Utilization (ISRU) technologies tend to become imperative to fulfill astronauts' needs. This article explores a way to use the lunar regolith as a source material for the additive manufacturing of complex objects, based on the selective laser melting (SLM) technique. A lunar regolith analog, Basalt of Pic d’Ysson (BPY), is used as a starting point for this study, to investigate the now demonstrated impact of amorphous analog content in the powder bed, substrate type, and post-SLM annealing treatments on the mechanical properties of 3D-printed objects. Improvements to the manufacturing and sample extraction stages are proposed to systematically reproduce the high compressive strength values obtained, thus contributing to the robustness and reliability of the process