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Tackling optimization and system driven engineering in coupling physical constraints with MBSE: the case of a Mobile autonomous line of products
No full textInternational audienceThe main goal of product line engineering is to build complex system architecture at the best quality, cost, resource ratio. The return on investment in terms of assessment is however not trivial, as systems to build rise in complexity. Moreover, the perspective of system of systems engineering that set up both historic and new systems in capabilities, and the introduction of more and more autonomous systems in architectures makes the anticipation of return on investment impossible to achieve without computer assistance. The necessary tools to assess as precisely as possible also involve a wide exploration of possibilities in an ever-changing context. The absence of mechanical or multi physical aspects in SysML-based tools, either in its version 1.3 or 2.0, makes it inefficient in representing or simulating robotic systems or system of system engineering. This article explains the benefits of tackling a classic Multi-Objective Knapsack Problem (MOKP) to the UGV product line items selection using a seamless system architecting toolchain. The association of MBSE (Model-based System Engineering), OR (Operation Research) and MBD (Model Based design) that generated various designs is presented. Our results in system engineering in UGV presents a Pareto Front of trade-offs that can count as numerous possibilities that sole MBSE or separate MBD simulation could not have represented as the best in the sense of . The simultaneous variations in both hardware and mechanical design show was entirely automated using standard tools with no redesign. This shows that seamless automations should pave the future of system engineering tools. With Operation research and Systems engineering tackling methods, our model upscale to real systems will shape System-Driven Engineering that will require new skills in system validation and verification and simulation analytics
Operations Research Approaches for the Satellite Constellation Design Problem
No full textInternational audienc
Market Structures, Competition and Innovation: Grounds for an Alternative Defence Industrial Policy
No full textInternational audienceSince the 1980s, most reforms in major arms-producing countries focus on keeping costs under control by either promoting competition between suppliers or by reducing information asymmetry through audits and controls. Indeed, cost escalation represents a challenge but, in fact, these reforms try to adjust the functioning of defence market rather than questioning the institutional features of this latter. The success of defence acquisition structures also explains their limits. The current organisation of defence market was perfectly adapted to the geostrategic context of Cold War and a technological momentum that favours symmetrical arms race between the United States and the Soviet Union. Even if these structures still help deliver advanced capabilities, they can be considered as not sufficient to cover all the operational needs of armed forces. The conception of capabilities needs to go beyond a long-term planning while industrial approaches open the way to more agile development and manufacturing. An alternative defence industrial policy is necessary to complement the existing one. More modular architectures for complex systems provide the opportunity to increase the reactiveness of capability deliveries and to foster both innovation and competition
JIT Compiler Security through Low-Cost RISC-V Extension
No full textInternational audienceLanguage Virtual Machines (VM) need to be extremely efficient and hence use complex engines such as a JIT compiler to speed up the usual bytecode interpretation loop. Their usage of low-level and security-critical tasks make them targets of choice. Enforcing low-cost fine-grained memory isolation has been an important research focus as a countermeasure to the most advanced JIT attacks. Memory isolation splits the components of an application with controlled communication and verified access to other resources. We present how custom instructions linked to hardware-enforced domain-checking could protect JIT code and data. We present incremental solutions and their corresponding custom instructions. The generated machine code and extended RISC-V Rocket come at a low-cost both in performance and intrusiveness
Time-vs. frequency-domain inverse elastic scattering: Theory and experiment
No full textInternational audienceThis study formally adapts the time-domain linear sampling method (TLSM) for ultrasonic imaging of stationary and evolving fractures in safety-critical components. The TLSM indicator is then applied to the laboratory test data of [22, 18] and the obtained reconstructions are compared to their frequency-domain counterparts. The results highlight the unique capability of the time-domain imaging functional for high-fidelity tracking of evolving damage, and its relative robustness to sparse and reduced-aperture data at moderate noise levels. A comparative analysis of the TLSM images against the multifrequency LSM maps of [22] further reveals that thanks to the full-waveform inversion in time and space, the TLSM generates images of remarkably higher quality with the same dataset
RUN: a robust cluster-based planning for fast self-reconfigurable modular robotic systems
No full textInternational audienceRecently, the industrial revolution has led to the emergence of a new generation of robotics called as modular robotic system (MRS). However, such new technology faces technical and practical challenges, in particular the self-reconfiguration. Subsequently, converting from one morphology to another is a complicated task for MRS that may take a long time because of the huge number of communications needed among the modules. In this paper, we propose an efficient and robust cluster-based planning, called RUN, for fast self-reconfigurable modular robots. RUN works on two stages and aims to group the modules into clusters in order to reduce the communication overhead between them and offers a fast reconfiguration process for the MRS. The first stage selects a set of modules, called cliques, and then, it divides the modules into clusters based on the shortest paths between modules and cliques. The second stage introduces two communication algorithms: the inter-module algorithm that allows an efficient communication between the cliques of the clusters, and the intra-module algorithm that reduces the communication number between the modules of the same clusters. We show the efficiency of RUN in terms of communication reduction and fast reconfiguration process, through simulations on Roombots compared to other exiting techniques
Authentification par empreinte radio pour l’IoT
No full textThe Internet of Things (IoT) defines the objects connected to the Internet, which integrate sensors and/or actuators. Their proliferation considerably increases the risk of cyber threats. Therefore, it is necessary to propose countermeasures in order to secure their communications, especially at the physical layer. One of the possibilities consists in ensuring the authenticity of the messages transmitted by using Radio Frequency Fingerprinting (RFF). Particularly, this type of method exploits the imperfections of the components of a radio transmitter, or even those of the propagation channel, which are considered as unique. The approach defended in this manuscript consists in studying the properties necessary for the use of the RFF in an IoT context, but also the methods which result from it, as well as their implementations. First, three properties were introduced: adaptability, scalability and complexity. Then, two RFF methods taking into account these properties have been proposed: the siamese networks for RFF and the RF eigenfingerprints method. These present a compromise between scalability and complexity, allowing possibility to address different use cases. Finally, the implementation of these methods was considered, either within a network or on IoT device.L’internet des objets ou Internet of Things (IoT) désigne les objets reliés à internet, qui intègrent des capteurs et/ou des actionneurs. Leur prolifération augmente considérablement le risque de cybermenaces, il est donc nécessaire de proposer des contre-mesures afin de sécuriser leurs communications, notamment au niveau de la couche physique. Une des possibilités consiste à s’assurer de l’authenticité des messages transmis en utilisant de l’authentification par empreinte radio ou Radio Frequency Fingerprinting (RFF). Plus particulièrement, ce type de méthodes exploitent les imperfections des composants d’un émetteur radio, voire celles du canal de propagation, qui sont considérées comme uniques. L’approche défendue dans ce manuscrit consiste à étudier les propriétés nécessaires à l’utilisation du RFF dans un contexte IoT, mais aussi les méthodes qui en découlent, ainsi que leurs implémentations. Tout d’abord, trois propriétés ont été introduites : l’adaptabilité, la scalabilité et la complexité. Ensuite, deux méthodes de RFF prenant en compte ces propriétés ont été proposées : les réseaux siamois pour le RFF et les RF eigenfingerprints. Celles-ci présentent notamment un compromis entre scalabilité et complexité, permettant d’adresser différents cas applicatifs. Pour finir, l’implémentation de ces méthodes a été considérée, que ce soit au sein d’un réseau ou au niveau d’un appareil IoT
Influence du cycle de cuisson sur le comportement en statique et en fatigue de composite carbone/époxy
No full textInternational audienc
Propagation de fissures dans des milieux élastiques avec énergie de surface anisotrope : expériences, simulations de champ de phase et mécanique de la rupture élastique linéaire
No full textAdditive manufacturing is receiving increasing attention due to its advantages in terms of modelling flexibility and allowing to easily design complex micro-structures. Through the manipulation of the printing strategy, we observed that fused deposition of polycarbonate can result in printed samples showcasing a distinct anisotropic behavior in fracture toughness, all the while retaining isotropic properties in elasticity.This thesis is dedicated to investigating fracture behavior within isotropic elastic media with anisotropic fracture toughness. The approach involves a combination of fracture experiments and numerical simulations. In the experimental part, we examine crack propagation under various loading conditions using diverse sample geometries, encompassing both Mode I and Mode I+II loading condition. In the numerical part, we adopt the phase-field modeling of brittle fracture based on a variational approach, using experimental data for calibrating and identification of the numerical parameters. Through these comprehensive methodologies, our objective is to foster a deeper comprehension of the interplay between printing patterns and the selection of crack paths. This understanding holds significant implications for guiding and controlling crack propagation in additive manufacturing-produced components. Besides, we adopted the classical based criteria Generalized Maximum Energy Release Rate to enhance our understanding of crack path selection and the relevant critical force.In the last part of this thesis, we presents some preliminary investigations regarding the potential emergence of Zig-Zag crack patterns in 3D printed specimens. Additionally, we delve extensively into the fracture behavior of printed specimens under cyclic loading, offering a comprehensive comparison between experimental observations and numerical forecasts.La fabrication additive attire une attention croissante en raison de ses avantages en termes de flexibilité de modélisation et de facilité de conception de microstructures complexes. Nous avons constaté qu'en manipulant la stratégie d'impression, les échantillons imprimés par dépôt de fusion de polycarbonate peuvent présenter un comportement fortement anisotrope en termes de résistance à la rupture, tout en conservant des propriétés isotropes en termes d'élasticité.Le focus de cette thèse est d'explorer le comportement en matière de rupture dans des milieux élastiques isotropes présentant une ténacité de rupture anisotrope, en utilisant une combinaison d'investigations expérimentales et de simulations numériques. Dans la partie expérimentale, nous examinons la propagation des fissures dans diverses conditions de chargement en utilisant des géométries d'échantillons variées, englobant à la fois le Mode I et le Mode I+II. Dans la partie numérique, nous adoptons la modélisation de la fissuration fragile par champ de phase basée sur l'approche variationnelle, en utilisant des données expérimentales pour l'étalonnage et l'identification des paramètres numériques. À travers ces méthodologies complètes, notre objectif est de favoriser une compréhension plus profonde de l'interaction entre les motifs d'impression et la sélection des trajectoires de fissures. Cette compréhension a des implications significatives pour guider et gérer la propagation des fissures dans les composants fabriqués par fabrication additive. De plus, nous adoptons les critères classiques basés sur le taux de restitution d'énergie maximale généralisé pour améliorer notre compréhension de la sélection des trajectoires de fissures et de la force critique correspondante.Dans la dernière partie de cette thèse, nous présentons quelques investigations préliminaires concernant l'éventuelle émergence d'un motif de fissure en Zig-Zag dans des spécimens imprimés en 3D. De plus, nous plongeons en profondeur dans le comportement de rupture des spécimens imprimés sous chargement cyclique, offrant une comparaison exhaustive entre les observations expérimentales et les prévisions numériques
