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Dynamic cloaking in elastic thin plates using architected metamaterials
No full textInternational audienceWe investigate the case of cloaking metamaterials for Kirchhoff-Love plates. We propose a design methodology still based on the geometrical transformation method initially introduced by Pendry [1], no longer with the aim of transforming the governing equation of Kirchhoff-Love plates but with the aim of generating curved waveguides forcing bending waves to propagate in the direction advocated by the preliminary idea of cloaking. Numerical results show that the resulting metamaterial is capable of making a hole in a plate invisible over a wide frequency band.</div
Neural Network Optimization on Classification Task from Event Data
No full textThe growing field of event-based vision offers unique opportunities for developing efficient and responsive computer vision systems. Unlike conventional frame-based imaging, event cameras asynchronously capture changes in pixel intensity, enabling high temporal resolution and re- duced data redundancy. These advantages make event-based vision particularly well-suited for real-time applications in dynamic environments. This study investigates the challenges and trade-offs involved in leveraging event vision data for neural network-based classification tasks
Sphingolipids in fungi: Biosynthesis and key roles in biological processes
No full textInternational audienceSphingolipids are complex lipids involved in the global cell physiology. They are significant components of the plasma membrane, contributing to the organization of lipids and anchoring of proteins. In all organisms, the biosynthesis pathway of sphingolipids begins in the endoplasmic reticulum and ends in the Golgi apparatus, where the biosynthesis of more complex sphingolipids occurs. In recent years, the key roles of sphingolipids in fungal biological processes and in the capacity of fungi to adapt to various environments have become of increasing interest. Sphingolipids are also promising as alternative targets to the emergence of multi-drug resistant pathogenic fungal strains. This review presents an outline of the fungal sphingolipid biosynthesis pathway, and an overview of recent advances in their biological roles
Cyanide removal from aqueous solution by oxidation with hydrogen peroxide in the presence of activated alumina-supported copper catalyst
No full textInternational audienceCyanide compounds are widely used in some electroplating, chemical and metallurgical industries. They are often found in their liquid discharges. This work highlights the performance of an activated alumina-supported copper catalyst in the removal of cyanide by oxidation with hydrogen peroxide in aqueous solution. The influence of catalyst dose, initial molar ratio of hydrogen peroxide/cyanides, temperature, and catalyst reuse was studied. The activated alumina-supported copper significantly enhanced the reaction rate showing a good catalytic activity. The efficiency of cyanide elimination was increased after 30 minutes of oxidation from 48% to 98% by increasing the catalyst dose from 1 to 10 g/L. Rising the temperature from 30°C to 40°C promoted cyanide removal. The catalyst can be recycled four times and show good stability. The kinetics of cyanide oxidation was revealed to be pseudo-first order with regarding cyanides. The rate constants as well as the activation energy were determined.</p
An Integrated Force Myography and SVM-Based Machine Learning System for Enhanced Muscle Exertion Assessment in Industrial Settings
No full textInternational audienceThis study proposes a novel approach for objective muscle exertion assessment in industrial settings, combining force myography (FMG) and support vector machines (SVM), bridging the gap between subjective and objective assessments while addressing limitations of existing technologies. To improve FMG data quality, an in-house-built conditioning interface for force-sensing resistor (FSR) sensor was developed, enhancing sensitivity and reducing drift. A novel hybrid feature selection method, combining multicollinearity analysis with forward selection, was implemented to analyze 31 time and frequency domain features extracted from the data. Various kernel functions (linear, polynomial, Gaussian) for the SVM model were evaluated using k-fold cross-validation to identify the optimal configuration. The results revealed 6 key features for optimal classification of Ratings of Perceived Exertion (RPE) using SVM. The Fine Gaussian kernel SVM model achieved the highest performance, demonstrating 97.09% accuracy, 96.83% precision, 96.79% recall, and a 96.81% F1-score. However, the potential of the Medium Gaussian kernel with larger datasets merits further investigation. Despite limitations such as a small sample size and focus on a single muscle group, our findings establish a foundation for a systematic approach to objective muscle exertion assessment. Future research should address these limitations to improve generalizability and develop robust ergonomic assessments for real-world industrial applications
Measuring acoustic velocity map in turbulent flow using sub-Nyquist-rate PIV system
No full textInternational audienceThe present study provides an experimental method for measuring acoustic velocity components (amplitude and spatial phase shift) in the presence of turbulent flows using either low-frequency particle image velocimetry (PIV) or laser Doppler velocimetry (LDV). The approach leverages compressed sensing (CS) principles to overcome the limitations of classical PIV techniques, such as the need for a reference signal for synchronization, large data size and long measurement duration. Theoretical aspects of CS for extracting acoustic components from PIV and LDV measurements are discussed. The proposed method is applied to both PIV and LDV systems, and the results are compared with microphone measurements. The results show the ability of the proposed experimental method to accurately measure acoustic velocity components at different frequencies and sound pressure levels in the presence of turbulent flow. The presented experimental method offers several advantages, including reduced data size, no need for phase-locking measurements and reduced measurement duration. The actual limitation is the need for a low noise-to-signal ratio (NSR). The effects of high NSR can be mitigated by increasing acquisition time in some cases. The non-intrusive nature of the method makes it valuable for aeroacoustic research. Ongoing research focuses on applying the method to higher-order duct modes and investigating its potential for modal decomposition using optical techniques
A Probabilistic Optimisation Approach to the Equitable Controller Location Problem
No full textInternational audienceThe ability of the Software-Defined Network (SDN) to transport traffic flows depends, in particular, on the SDN switches being able to communicate with SDN controllers, which are responsible for the setup of network connections and the configuration of switches. Since in principle the number of SDN controllers is limited they must be installed in a set of carefully selected node locations. Whereas the problem of controller placement is well defined and has been thoroughly studied and effectively solved for the nominal network state, it becomes difficult when the network is subject to attacks, especially as they can occur anywhere and anytime. In this paper we tackle the problem of controller placement resilient to network attacks considering probabilistic characterisation of attacks and equitable access of switches to controllers. We treat the problem as a specific facility location problem with the objective of providing resilience to network attacks, and analyze a couple of major solution fairness criteria. We derive a number of Mixed-Integer Linear Programming (MILP) problem models that exploit robust optimization and fair optimization concepts and techniques, and examine their effectiveness by means of a numerical study that uses five transport networks
L'UTC ou la saga des technologues
No full textInternational audiencePourquoi des étudiants choisissent-ils l’UTC en 1973, sans locaux, sans diplôme ? Non pas le rêve, mais peut-être la promesse d’être les artisans du changement, de le faire advenir, d’être dans la course d’un monde où l’évolution technologique modifie les praxies sociales, les repères spatiotemporels… L’UTC affirme la technologie au plus haut niveau de l’enseignement supérieur et de la recherche. Ni école, ni université de science, entre-deux institutionnel, l’UTC opère une convergence entre ingénierie et recherche, université et entreprise sur le registre de l’action. Écho à l’urgence de transformer les institutions en décalage avec la dynamique du corps social, elle bouscule la tradition du système français. L’UTC est une unité active de convergence (UAC) c’est-à-dire transformatrice de son environnement par des collaborations improbables. Elle émerge avec une mission d’expérimentation pédagogique, directement en prise avec l’évolution des politiques publiques. Cette histoire est d’abord celle d’une aventure collective qui inscrit progressivement la recherche technologique et la formation de « technologues » comme une évidence des écosystèmes d’innovation. Des entrepreneurs académiques et institutionnels s’emploient à réussir le pari, soutenus au départ par des parrains industriels, politiques, chercheurs et hauts-fonctionnaires. À l’inverse, opposition ouverte ou dissimulée, désaccords plus diffus, l’inertie des systèmes de la configuration académique bride le développement de l’organisation, tout en s’en inspirant. Entre innovation organisationnelle, intégration territoriale et légitimité institutionnelle (phénomène d’isomorphisme...), elle semble suivre un cycle pour devenir une institution intermédiaire. C’est cette saga que nous livrent les témoignages, archives, presse… L’étude s’est concentrée sur l’émergence de l’institution jusqu’aux alentours de 2005, pour ne suivre ensuite que quelques pistes et tenter de clôturer ce premier cycle de développement
Que restera-t-il de l’auteur numérique ?: Préservation et archives de la littérature numérique
No full textInternational audienceProposant une typologie de la littérature numérique basée sur sa relation avec la naissance du Web, cet article examine la transformation de la fonction d’auteur·e et de la notion d’œuvre littéraire à l’aune de l’évolution des formes littéraires numériques. Cette fonction étant liée à la fois à la genèse des œuvres et à leur contexte de diffusion et de réception, il s’agit d’étudier les effets poétiques et esthétiques produits par des dispositifs littéraires numériques, mais aussi des questions de propriété et d’archivage des œuvres
Editorial on fundamentals of high-temperature corrosion and protection of materials
No full textInternational audienceThe study of high-temperature oxidation and corrosion is increasingly diversified due to its numerous applications. The following papers focus on the fundamental aspects associated with the durability of nickel-based superalloys, CrSi alloys, and titanium alloys for aeronautics, the durability of metals and oxides in current and future nuclear reactors, and the use of oxidation as a fabrication means to develop an oxide as a functional element in interconnects used in solid oxide fuel cell devices. These material/environment systems are often complex. Nonetheless, these studiesare founded on a common scientific base at the intersection of physical metallurgy, thermodynamics, and chemical kinetics, with the mechanical properties of materials sometimes playing a significant role. It is essential to test this base, apply it to new cases, and develop it further when gaps in the theory are identified. The thermodynamic modeling of complex systems, such as predicting the thermodynamic behavior of fission products encountered between the (U,Pu)O2 fuel pellet and the cladding in nuclear reactors, is progressing thanks to the development of databasesand tools based on the CALPHAD (Computer Coupling of Phase Diagrams and Thermochemistry) approach. This approach also allows for considering the chemical potential gradients of species transporting within complex systems. However, we are still far from predicting the microstructure and composition of any reaction product. Also, many couplingmechanisms remain to be identified, for example, between oxidizing species (such as N and O in titanium alloys in one of the following papers) or between various types of interactions in model or complex systems. Finally, there exists an almost infinite number of new systems and material assemblies to study, as well as many little-known systems, such as the oxidation of PuGa alloys or thermal barriers based on high-entropy complex oxide solutions. The following papers stem from presentations at the 11th International Conference on High-Temperature Corrosion and Protection of Materials (HTCPM 2024), held at Les Embiez Island, France, on June 9–14, 2024