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Quand l'IA explore les prémices d'une vie artificielle
No full texthttps://www.pourlascience.fr/sd/informatique/quand-l-ia-et-les-automates-cellulaires-explorent-les-premices-de-l-evolution-26650.phpInternational audienceImaginons une simulation informatique dans laquelle un grand nombre d’entités se modifient en fonction de l’activité de leurs voisinage, un peu à la manière de composants chimiques simulés qui interagissent entre eux au cours du temps. Au début, dans cet univers informatique, il y a juste de la matière dispersée au hasard, et quelques règles abstraites de physique artificielle. En particulier il n'y a rien que l’on puisse qualifier de vivant : ni corps, ni cerveau, ni action, ni perception, bref pas d'individus et pas d'évolution. Et puis spontanément apparaissent des sortes de petites créatures artificielles : des formes localisées qui se déplacent, contournent des obstacles, peuvent se reconstruire quand leur corps est endommagé, voire parfois même se reproduire entre elles. Serait-ce une forme d'apparition d’une vie artificielle dans un programme informatique ? Récemment, nous avons réalisé des simulations informatiques de ce type, mettant en œuvre des automates cellulaires continus d’un nouveau type, et dans certaines conditions, nous avons observé la formation spontanée de telles structures. Nous allons découvrir comment ces simulations, qui appartiennent à un domaine scientifique appelé Vie Artificielle, permettent de poser des questions essentielles sur l’origine de processus évolutifs dans le vivant.https://www.pourlascience.fr/sd/informatique/quand-l-ia-et-les-automates-cellulaires-explorent-les-premices-de-l-evolution-26650.ph
SoSAF: A Pharo-Based Framework for Enhancing System of Systems Dependencies Analysis
No full textSystem of Systems (SoS) architecture has long been used in system engineering to address increasing and complex requirements. By focusing on the temporal and spatial dynamics of their components, one of their properties is the dependencies between their components. From this perspective, a failure in a component can trigger cascading effects throughout the whole infrastructure. It is crucial to assess how dependencies affect the system's capabilities during the design phase to prevent critical configurations. The first step involves modeling these systems along with their dependencies. Approaches in the literature on SoS dependencies modeling focus on either design, analysis, or execution. Actually, to the best of our knowledge, there are no proposals for a single model that can take all three phases into account. This situation leads to the creation of a gap between these phases, making dependency analysis complex and time-consuming. Furthermore, it is remarkable that there is no model verification process for the approaches studied in the literature. It's worth noticing that, the approaches studied in the literature do not take real-time interactive simulation into account. Given the dynamic nature of SoS, it's crucial to be able to run the models in an interactive simulation to interact with them and update their parameters. The identified locks regarding this subject are: (i) developing a unified and consistent model for design, execution, and dependencies analysis, (ii) handling interaction within the model during simulation.We introduce in this article the first results of the development of an experimental framework called System of Systems Architecture Framework (SoSAF) for the design, simulation, and analysis of the impact of dependencies in SoS operability. To address the issue (i), the SoSAF framework introduces a meta-model SoSAF Meta-Model (SM2) developed with the Meta-Object Facility (MOF) specifications, coupled with a model control layer defined with Object Constraint Language (OCL). For interactive simulation (ii) in SoSAF, we present a synchronous and interactive simulation engine on the Pharo environment. By developing this framework on Pharo, we address the issue of interactive simulation. Indeed, thanks to the tools integrated within the Pharo image, such as the inspector, we can interact with a model during the execution of the simulation. To validate our framework's ability to represent and analyze the impact of dependencies, we conducted a case study on a swarm of Unmanned Vehicles (UVs). The case study demonstrates the framework's ability to represent the specifications of SoS and to analyze the impact of dependencies on the operability of all components.</p
IDS-DEEP: a strategy for selecting the best IDS for Drones with heterogeneous EmbEdded Platforms
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Electrocatalytic dehydrogenative and defluorinative coupling between aldehyde-derived N , N -dialkylhydrazones and fluoromalonates: synthesis of 2-pyrazolines
No full textInternational audienceAn electrocatalytic synthesis of 2-pyrazolines via dehydrogenative and defluorinative cross-coupling reactions between (hetero)arylaldehyde-derived N,N-dialkylhydrazones and fluoromalonates is disclosed. Salient features of this work include (i) readily available starting materials, (ii) practical reaction conditions, and (ii) a formal oxidative (4 + 1)-cycloaddition via triple C–H bond functionalization. Cyclic voltammetry analyses support the electrocatalytic formation of an α-fluoromalonyl radical
Turbulence-induced vibration in annular flow of a rigid cylinder mounted on a cantilever beam
No full textInternational audienceThis study investigates the fluid-structure interaction of two coaxial cylinders separated by a Newtonian fluid under turbulent axial flow. The theoretical framework treats the inner cylinder as a rigid body mounted on a flexible blade modeled as a Rayleigh beam. The goals of this study are to determine the free vibration modes and frequencies, identify the fluid-elastic instability threshold, and establish an analytical expression for the mean-square displacement of the structure. The approach integrates various fluid forces and torques, such as Archimedean thrust, fluid-elastic forces for a quiescent fluid, fluid-elastic forces due to flow, and the effects of fluid turbulence. The new approach reveals that vibration modes, frequencies, instability thresholds, and meansquare displacement each depend on a different set of dimensionless parameters: 8, 11, and 12, respectively. These parameters include the cylinder aspect ratio and fluid gap radius ratio. By incorporating models from the literature for viscous friction coefficients, turbulent pressure power spectral density, and coherence function, the study demonstrates stability conditions and the scaling of mean-square displacement with Reynolds number squared. The study, presented in a fully dimensionless formulation, aims to assist engineers in constructing small-scale experiments representative of pressure vessel vibrations. To facilitate this, a Python code for system stability determination and mean-square displacement calculation is provided.</div
Infrared imaging surface roughness criticality assessment of Wire Arc Additive Manufactured specimens
No full textInternational audienc
Structural characterization of N-acyl-homoserine lactones from bacterial quorum sensing using LC–MS/MS analyses after Paternò-Büchi derivatization in solution
No full textInternational audienceBacterial quorum sensing is a chemical language allowing bacteria to interact through the excretion of molecules called autoinducers, like N-acyl-homoserine lactones (AHLs) produced by Gram-negative Burkholderia and Paraburkholderia bacteria known as opportunistic pathogens. The AHLs differ in their acyl-chain length and may be modified by a 3-oxo or 3-hydroxy substituent, or C = C double bonds at different positions. As the bacterial signal specificity depends on all of these chemical features, their structural characterization is essential to have a better understanding of the population regulation and virulence phenomenon. This study aimed at enabling the localization of the C = C double bond on such specialized metabolites while using significantly lower amounts of biological material. The approach is based on LC–MS/MS analyses of bacterial extracts after in-solution derivatization by a photochemical Paternò-Büchi reaction, leading to the formation of an oxetane ring and subsequently to specific fragmentations when performing MS/MS experiments. The in-solution derivatization of AHLs was optimized on several standards, and then the matrix effect of bacterial extracts on the derivatization was assessed. As a proof of concept, the optimized conditions were applied to a bacterial extract enabling the localization of C = C bonds on unsaturated AHLs
Substructuring based FEM-BEM coupling for Helmholtz problems
No full textInternational audienceThis talk concerns the solution of the Helmholtz equation in a medium composed of a bounded heterogeneous domain and an unbounded homogeneous one. Such problems can be expressed using classical FEM-BEM coupling techniques. We solve these coupled formulations using iterative solvers based on substructuring Domain Decomposition Methods (DDM), and aim to develop a convergence theory, with fast and guaranteed convergence. A recent article of Xavier Claeys proposed a substructuring Optimized Schwarz Method, with a nonlocal exchange operator, for Helmholtz problems on a bounded domain with classical conditions on its boundary (Dirichlet, Neumann, Robin). The variational formulation of the problem can be written as a bilinear application associated with the volume and another with the surface, for which, under certain sufficient assumptions, convergence of the DDM strategy is guaranteed.In this presentation we show how some specific FEM-BEM coupling methods fit, or not, the previous framework, in which we consider Boundary Integral Equations (BIEs) instead of classical boundary conditions. In particular, we prove that the symmetric Costabel coupling satisfies the framework assumptions, implying that the convergence is guaranteed
The Silent Teacher: Aesthetic Education According to Ursula K. Le Guin
No full textInternational audienceWhat is the pedagogical place of silence in the Anthropocene classroom? Should we as teachers—particularly as teachers involved in the education of aesthetic sensibilities—understand our classrooms as sites in which awareness of our Anthropocene predicament is spread, sites in which a general sense of the urgency of our times is disseminated? And is this awareness not best spread via explicit facts and data, the key story of climate change and biodiversity loss, with these themes serving as the background against which we interpret the symbolic abstractions of aesthetic objects? This article follows Ursula Le Guin's example to a conclusion that perhaps differs from the consensus. Our overall argument is that cultivating a certain sort of silence relative to the Anthropocene can be profoundly educational for our students, if—of course—that silent teaching is done artfully
An Open Source Hydroacoustic Benchmarking Framework for Geophonic Signal Detection
No full textInternational audiencePassive hydroacoustic studies have underscored the efficiency and relevance of deploying autonomous hydrophones for the surveillance of underwater geophony. In particular, monitoring networks have been deployed for detecting SOFAR-propagating hydroacoustic waves generated by seismic events and locating their sources. The technique has been extended to study other hydroacoustic signals, such as P-waves from teleseismic events or impulsive waves generated by seawater-lava interactions. A significant challenge in this endeavor lies in the time required for the manual detection and annotation of these signals in longterm records. To address this issue, we tested the feasibility of implementing automated algorithms based on machine learning to detect and identify these various signals, and obtained satisfying classification and time picking accuracies. We incorporated those models in a benchmarking framework, proposing a training dataset, two evaluation datasets, two tasks to solve and the evaluations of the mentioned models on them. The goal of this framework is to foster the development of new models in the community, as it gives a clear way to evaluate them