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Roadmap: Emerging Platforms and Applications of Optical Frequency Combs and Dissipative Solitons
No full textThe discovery of optical frequency combs (OFCs) has revolutionised science and technology by bridging electronics and photonics, driving major advances in precision measurements, atomic clocks, spectroscopy, telecommunications, and astronomy. However, current OFC systems still require further development to enable broader adoption in fields such as communication, aerospace, defence, and healthcare. There is a growing need for compact, portable OFCs that deliver high output power, robust self-referencing, and application-specific spectral coverage. On the conceptual side, progress toward such systems is hindered by an incomplete understanding of the fundamental principles governing OFC generation in emerging devices and materials, as well as evolving insights into the interplay between soliton and mode-locking effects. This roadmap presents the vision of a diverse group of academic and industry researchers and educators from Europe, along with their collaborators, on the current status and future directions of OFC science. It highlights a multidisciplinary approach that integrates novel physics, engineering innovation, and advanced researcher training. Topics include advances in soliton science as it relates to OFCs, the extension of OFC spectra into the visible and mid-infrared ranges, metrology applications and noise performance of integrated OFC sources, new fibre-based OFC modules, OFC lasers and OFC applications in astronomy
Dynamic modeling of a liquid piston compressor system including conjugate heat transfer
No full textInternational audienceEfficient and cost-effective hydrogen storage necessitatesquick compression across significant pressure ranges (usu-ally up to 700 bar), while keeping heat generation toa minimum during the process. This can be achievedby improved understanding of gas-to-wall heat transferenhancement in hydrogen compression systems, carefuldesign and operational optimisation.In this context,the present paper introduces a 0D/1D lumped numericalmodel of a liquid piston compressor for hydrogen applica-tions. Heat transfer is considered as (i) convective at theliquid-gas interface, (ii) conductive within the gas volumebased on a 1D approach accounting for thermal stratifica-tion, and (iii) as conjugate at the gas-to-wall interface. Toachieve a pressure ratio of 30 (from 15 to 450) bar, at apower density of approximately 65kW/m3, the compres-sion energy cost reaches 1.85kW h/kg. Further, variousstandard pressure vessels materials with different thermaland mechanical properties are considered, highlighting thepotential compromise between lightweight and thermal ef-ficiency
Movement sonification during haptic exploration shifts emotional outcome without altering texture perception
No full textInternational audienceBackground: Adding movement sonification to haptic exploration can change the perceptual outcome of a textured surface through multisensory processing. We hypothesized that auditory-evoked emotions influence the appraisal of textured surfaces, with corresponding changes reflected in cortical excitability.Methods: Twelve participants actively rubbed two different textured surfaces (slippery and rough) either without movement sonification, or with pleasant or disagreeable movement sonification.Results and discussion: We found that sounds, whether agreeable or disagreeable, did not change the texture appraisal. However, the less pleasant surface was associated with a stronger negative hedonic valence, particularly when paired with disagreeable movement sonification. Time frequency analyses of electroencephalography (EEG) activities revealed a significant reduction in beta-band power [15-25 Hz] within the source-estimated sensorimotor and superior posterior parietal cortices when contrasting both pleasant and unpleasant sounds with the silent touch. This suggests that the primary somatosensory cortices together with the superior parietal regions participated in the audio-tactile binding, with both pleasant and unpleasant sounds. In addition, we observed a significant increase in beta-band power in medial visual areas, specifically when disagreeable movement sonification was paired with tactile exploration. This may reflect a disengagement of visual cortical processing, potentially amplifying auditory-driven emotional responses and intensifying the perceived unpleasantness of the explored surfaces.Conclusion: Our results offer new insights into the neural mechanisms by which hedonic valence of auditory signals modulates emotional processing, without disrupting the perceptual analysis of texture properties
Microscopic Modeling of Interfaces in Cu-Mo Nanocomposites: The Case Study of Nanometric Metallic Multilayers
No full textInternational audienceNanocomposites composed of Cu and Mo were investigated by means of molecular dynamics (MD) simulations to study the incoherent interface between Cu and Mo. In order to select an appropriate potential capable of accurately describing the Cu-Mo system, five many-body potentials were compared: three Embedded Atom Method (EAM) potentials, a Tight Binding Second Moment Approximation (TB-SMA) potential, and a Modified Embedded Atom Method (MEAM) potential. Among these, the EAM potential proposed by Zhou in 2001 was determined to provide the best compromise for the current study. The simulated system was constructed with two layers of Cu and Mo forming an incoherent fcc-Cu(111)/bcc-Mo(110) interface, based on the Nishiyama–Wassermann (NW) and Kurdjumov–Sachs (KS) orientation relationships (OR). The interfacial energies were calculated for each orientation relationship. The NW configuration emerged as the most stable, with an interfacial energy of 1.83 J/m², compared to 1.97 J/m² for the KS orientation. Subsequent simulations were dedicated to modeling Cu atomic deposition onto a Mo(110) substrate at 300 K. These simulations resulted in the formation of a dense layer with only a few defects in the two Cu planes closest to the interface. The interfacial structures were characterized by computing selected area electron diffraction (SAED) patterns. A direct comparison of theoretical and numerical SAED patterns confirmed the presence of the NW orientation relationship in the nanocomposites formed during deposition, corroborating the results obtained with the model fcc-Cu(111)/bcc-Mo(110) interfaces
Temporal Reversibility of Reactive Systems Out of Equilibrium: Molecular Dynamics Simulation
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Changes, interactions and drivers of soil chemical, physical and biological properties after repeated application of organic waste products in two contrasted long-term field experiments in France
No full textInternational audienceRecycling organic waste products (OWP) is known to influence soil physical, chemical, and biological properties, yet few studies have compared the long-term effects of different OWP type across multiple sites. This study examined the impacts of repeated OWP application on soil properties in two French long-term field experiments: QualiAgro and PROspective (20 and 18 years, respectively). The OWP included dehydrated urban sewage sludge (SLU), green waste and SLU compost (GWS), biowaste compost from source-separated municipal organic waste co-composted with green waste (BIO), municipal solid waste compost (MSW), farmyard manure from a dairy cow farm (FYM), and composted FYM from open-air composting on a concrete platform (FYMC). The application of OWP led to increased soil nutrient levels and trace element availability, and stimulated microbial biomass and enzyme activities, while the response of nematode varied depending on site and OWP type. Biological properties were less affected than physico-chemical properties, though the OWP application enhanced soil microbial biomass and specific enzyme activities. The impact on soil nematode communities varied depending on OWP type and site. Strong correlations were observed among soil property changes, with exogenous carbon and nutrient inputs from OWP identified as key drivers. Larger changes were noted in QualiAgro, where OWP application rates were higher and initial soil quality lower. These findings highlight that OWP applications, depending on their type, rate, and initial soil conditions, can significantly alter soil properties
Mesolithic settlements (9th to 6th millennia cal.BCE) at Roquemissou (Aveyron, France)
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Contrôle optimal de certaines classes de processus de rafle et applications
No full textThis thesis investigates the optimal control of dynamical systems governed by sweeping processes, with a particular focus on both implicit and explicit formulations involving convex and polyhedral geometries. These systems, characterized by highly nonsmooth differential inclusions with state-dependent constraints, arise naturally in models of elasto-plasticity, hysteresis, and contact mechanics. The primary challenge in controlling such systems arises from the discontinuous nature of the normal cone operator, which obstructs the direct application of classical optimal control tools.We begin by establishing a Pontryagin-type maximum principle for a class of optimal control problems governed by implicit sweeping processes with general endpoint constraints. The sweeping set is assumed to be polyhedral and control-dependent, and the dynamics include state and control variables in both the inclusion and perturbation terms. The analysis relies on precise coderivative estimates for the metric projection mapping onto polyhedral convex sets. Applications include variational inequalities and projected dynamical systems, such as generalized Lotka–Volterra models.To support this framework, we conduct a detailed study of the coderivative geometry of projection operators. We present new estimates for the Dini and Mordukhovich coderivatives of the metric projection mapping, focusing on two important classes of convex sets: those with strictly Hadamard differentiable boundaries and polyhedral sets. These results are instrumental in handling the nonsmooth structure of sweeping processes and form a critical component in deriving necessary optimality conditions.We further propose a novel approximation scheme for solving optimal control problems governed by explicit sweeping processes, which are inherently more challenging due to their nonsmoothness. By introducing a family of implicit sweeping dynamics, we regularize the system in a way that enables the application of classical maximum principle techniques. We establish convergence results and validate the method through an application to the optimal control of a single degree-of-freedom elasto-plastic oscillator, a benchmark model in structural mechanics and seismic engineering.Overall, the dissertation provides a unified theoretical and methodological framework for the optimal control of sweeping processes, contributing new insights to nonsmooth analysis, variational inequalities, and control theory.Cette thèse porte sur le contrôle optimal de systèmes dynamiques gouvernés par des processus de rafle de Moreau (sweeping processes), en mettant particulièrement l’accent sur les formulations implicites et explicites en considérant des ensembles polyédriques et convexes. Ces systèmes, caractérisés par des inclusions différentielles fortement non régulières avec des contraintes dépendantes de l’état ou du contrôle, apparaissent naturellement dans des modèles d’élasto-plasticité, d’hystérésis et de mécanique du contact. La difficulté principale dans le contrôle de tels systèmes réside dans le caractère discontinu de l’opérateur de cône normal, ce qui empêche l’application directe des outils classiques du contrôle optimal.Nous commençons par établir un principe du maximum de type Pontryagin pour une classe de problèmes de contrôle optimal gouvernés par des processus de rafle implicites avec des contraintes terminales générales. L’ensemble balayé est supposé polyédrique et dépendant du contrôle, et la dynamique fait intervenir à la fois l’état et le contrôle dans l’inclusion différentielle ainsi que dans le terme de la perturbation. L’analyse repose sur des estimations précises de la codérivée de l’application projection sur des ensembles convexes et/ou polyédriques. Des applications sont données, notamment aux inégalités variationnelles et aux systèmes dynamiques projetés, tels que les modèles de Lotka–Volterra généralisés.Dans ce cadre, nous menons une étude détaillée sur le calcul de la codérivée de l’opérateur de projection. Nous présentons de nouvelles estimations pour les codérivées de Dini et de Mordukhovich de cette application de projection, en nous concentrant sur deux classes importantes d’ensembles convexes : ceux à frontière strictement différentiable au sens de Hadamard, et les ensembles polyédriques. Ces résultats sont essentiels pour traiter la structure non régulière des processus de rafle de Moreau et constituent un élément central dans la dérivation des conditions nécessaires d’optimalité.Nous proposons ensuite un schéma d’approximation original pour la résolution de problèmes de contrôle optimal gouvernés par des processus de Moreau explicites, qui sont plus complexes en raison de leur non régularité intrinsèque. En introduisant une famille de rafle de Moreau implicites, nous régularisons le système de manière à permettre l’application des techniques classiques du principe du maximum. Nous établissons des résultats de convergence et validons notre approche à travers une application au contrôle optimal d’un oscillateur élasto-plastique à un degré de liberté, un modèle de référence en mécanique des structures et en ingénierie sismique.Dans l’ensemble, cette dissertation propose un cadre théorique et méthodologique unifié pour le contrôle optimal des processus de rafle de Moreau, apportant des contributions nouvelles à l’analyse non lisse, aux inégalités variationnelles et à la théorie du contrôle
A Preprocessing Framework for MeshCNN-based Surface Segmentation of Fragmented 3D Heritage Objects
No full textInternational audienceSurface segmentation of 3D meshes is critical for digital reconstruction and cultural heritage preservation. Deep learning approaches such as MeshCNN can learn directly from mesh geometry, but cannot process archaeological fragments due to incompatible input requirements. Fractured heritage meshes vary widely in resolution (2,380–111,788 faces) and contain non-manifold edges and topological defects, while MeshCNN requires fixed edge countsand manifold connectivity. We propose a preprocessing framework that addresses this problem throughresolution normalization to 3,000 faces, topology validation, and label reprojection via surface distance mapping. Experiments on 36 archaeological fragments show that MS-DBSCAN achieves 67.93% region-based accuracy on preprocessed meshes, confirming that the framework preserves segmentation quality. MeshCNN achieves 44.40% accuracy, demonstrating that edge-based deep learning can now operate on heritage data. The performance gap reflects limited training data (27 fragments) rather than preprocessing failures. This work establishes preprocessing as necessary for applying deep learning to archaeological meshes and identifies few-shot learning as an important direction for future work
