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Artwork recommendations guided by foundation models: survey and novel approach
No full textInternational audienceMuseums and art galleries use modern technologies to engage visitors and attract not only specialists but also the general public, by providing recommendations for interactive studying and observing their collections. These recommendations can be created on the base of artwork similarity defined by using fine-tuned deep neural networks. In this paper, we explore the possibilities of fine-tuning foundation models using the Low-Rank-Adaptation (LoRA) fine-tuning technique for the classification task and perform a similarity search based on features extracted with fine-tuned models. Using LoRA technique allows to use and switch easily between several fine-tuned models with only one frozen backbone, this is useful in the case of using large models on mobile devices with limited storage space. During fine-tuning, we examined the influence of hyperparameters on two DINOv2 models' performance and found their reasonable combination according to a number of trainable parameters and performance, achieved on the relatively small artistic dataset. We achieved state-of-the-art accuracy for genre classification on the WikiArt dataset with the proposed approach
A convergent Plug-and-Play Majorization-Minimization algorithm for Poisson inverse problems
No full textIn this paper, we present a novel variational plug-and-play algorithm for Poisson inverse problems. Our approach minimises an explicit functional which is the sum of a Kullback-Leibler data fidelity term and a regularisation term based on a pre-trained neural network. By combining classical methods, in particular the Richardson-Lucy algorithm, with recent advances in gradient-based denoisers, we allow the use of pre-trained Gaussian denoisers without sacrificing convergence guarantees. The algorithm is formulated in the majorization-minimization framework, which guarantees convergence to a stationary point. Numerical experiments demonstrate its state-of-the-art performance in deconvolution and highlight the versatility of the method for other Poisson-based inverse problems, such as computed tomography reconstruction
Twins in Kähler and Sasaki geometry
No full text35 pages, 3 figuresWe introduce the notions of weighted extremal K{\"a}hler twins together with the related notion of extremal Sasaki twins. In the K\"ahler setting this leads to a generalization of the twinning phenomenon appearing among LeBrun's strongly Hermitian solutions to the Einstein-Maxwell equations on the first Hirzebruch surface \cite{Leb16} to weighted extremal metrics on Hirzebruch surfaces in general. We discover that many twins appear and that this can be viewed in the Sasaki setting as a case where we have more than one extremal ray in the Sasaki cone even when we do not allow changes within the isotopy class. We also study extremal Sasaki twins directly in the Sasaki setting with a main focus on the toric Sasaki case
Life Cycle Assessment of Concrete Recycling Solutions in Light of Their Technical Complexity
No full textInternational audienceWaste management is a key step for addressing both the environmental impact and the growing demand for resources in the construction industry. To answer these challenges, various technologies are available, carrying different environmental impacts and sociotechnical implications. For concrete waste, recycling is the most common solution. Two main recycling roads were identified, leading to products that have low or high value and implying different technical developments and environmental impacts. This study first proposed to characterize recycling technologies by their technical degree, reflecting the complexity needed to process waste. It secondly compared their environmental impacts using LCA methodology to assess which technical complexity led to minor environmental consequences and under what conditions. The results revealed that the technologies with a low technical degree tended to have a lower environmental impact than the ones with a higher technical degree when only the generated impacts were considered. The reverse was observed when considering the aggregated impacts due to the environmental benefits provided by the potentially avoided products
On dissociated infinite permutation groups
No full text34 pagesThe goal of this paper is threefold. First, we describe the notion of dissociation for closed subgroups of the group of permutations on a countably infinite set and explain its numerous consequences on unitary representations (classification of unitary representations, Property (T), Howe-Moore property, etc.) and on ergodic actions (non-existence of type III non-singular actions, Stabilizer rigidity, etc.). Some of the results presented here are new, others were proved in different contexts. Second, we introduce a new method to prove dissociation. It is based on a reinforcement of the classical notion of strong amalgamation, where we allow to amalgamate over countable sets. Third, we apply this technique of amalgamation to provide new examples of dissociated closed permutation groups, including isometry groups of some metrically homogeneous graphs, automorphism groups of diversities, and more
Le Comité de l’environnement polaire, vigile des Terres australes et antarctiques françaises
No full textInternational audienceLe Comité de l'environnement polaire a été institué par le décret n° 93-740 du 29 mars 1993 portant création d'un comité de l'environnement polaire 1 et placé auprès du ministre chargé de l'Environnement qui en assure le fonctionnement et le secrétariat (C. envir., art. D. 133-34) 2 , sans pour autant que cela remette en cause son indépendance. De fait, en pratique, si l'agent du ministère de la Transition écologique (en l'occurrence, de la Direction de l'eau et de la biodiversité) placé auprès de lui assure l'organisation matérielle des réunions du Comité en liaison avec son président, il s'efface lorsque le Comité se réunit à huis clos de sa propre initiative pour discuter de sujets « sensibles » ou construire un avis sur autosaisine appelant des discussions « fermées », garantissant un libre échange sur des questions pouvant mettre en cause la politique environnementale déployée dans les TAAF. Le secrétariat, quant à lui, est assuré par le service « Environnement » de l'administration des TAAF (préparation des dossiers des pétitionnaires examinés par le Comité, verbatim des séances, remboursement des dépenses exposées par les membres du Comité)
Development and mechanical characterization of short fibers ceramic composites through bending tests
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Investigating efficiency and environmental impact of type 4 hydrogen tank for heavy mobility
No full textInternational audienceThe presentation attempts to establish the state of progress of HYperStock project, as a brick of the huge PEPR decarbonized H2 french program. The project aims at consolidating the French scientific leadership in the field of storage and distribution of hydrogen under high pressure. This is an essential element of the hydrogen value chain on which the research and innovation effort must focus, particularly with a view to decarbonizing heavy mobility. To reduce the carbon impact of compressed hydrogen transport and storage solutions, the focus shall concentrate on the materials used, by integrating their synthesis, involved processes and recyclability aspects. The material challenge is then considerable and we propose to set a material reference under severe H2 environment, coupled with selection methodologies, allowing to study and identify the potential of new 'material' candidates. Based on the mechano-physical-chemical properties of these candidates, the project will offer a detailed approach to attest the potential of these materials with respect to the severe solicitations to which they are subjected, as well as the expected characteristics. Our approach in this project is to investigate deeply the potential of two large families of materials for storage and transportation of H2: for the development of technological solutions for hydrogen distribution and storage. It will also serve to build new synergies and collaborations within the scientific community involved in the hydrogen domain. The two main indicators of success and follow-up of the project are, on the one hand, the prospect of a 20% decarbonization of type 3 and 4 high-pressure storage solutions and, on the other hand, a significant reduction in safety indexes, through the extension of the lifespan, the reduction of the wall thickness required and the cost reduction of maintenance and periodic inspection
Chitin-binding protein behavior at chitosan interface studied by quartz crystal microbalance with dissipation monitoring (QCM-D): Binding quantification, orientation and affinity constants
No full textInternational audienceA full comprehension of chitosan interaction with proteins is yet to be achieved, in view of the complexity of the physico-chemical behaviors found in the chitosan family, and the diversity of possible protein interaction mechanisms. In this work, we studied the interactions between chitosans and wheat germ agglutinin (WGA), a lectin that can bind chitin thanks to an amino-acid pattern called the hevein-like chitin-binding domain (CBD). The specificity of CBD interactions with chitin/chitosan chains and the impact of the degree of acetylation (DA) of chitosan have been studied by quartz crystal microbalance with dissipation monitoring (QCM-D). The mass per unit area of WGA adsorbed on chitosan was six times higher than that of immunoglobulin G (IGG), which does not contain a CBD. The mass per unit area of deposited WGA was also almost twice as high at higher chitosan DAs (54%, 67%, 76%) than at lower DAs (0.5%, 15%, 35%), evidencing more specific interaction with “chitin-like” chitosans. WGA is a dimer at neutral pH and presents 4 CBDs on each monomer. The repartition of these CBDs seems to allow for reorganization of WGA on the chitosan surface in order to favor the interactions of this chitosan with a higher number of proteins. Furthermore, the binding kinetics have been assessed and modelled with a two-step association model, providing insights on the observed association constants. These results indicate that QCM-D constitutes a suitable method for the analysis of lectin CBD–chitosan dynamic interactions and could be applied to other types of proteins, in particular CBD proteins or further used in biosensor elaboration or biomaterial coating assessment with chitosan of different DAs
Photoluminescence Monitored Sustainable Digital Photocorrosion of GaAs/Al 0.35 Ga 0.65 As Quantum Well Microstructures
No full textInternational audienceDigital photocorrosion (DIP) of GaAs/AlGaAs nanoheterostructures is an attractive method for detecting surface‐immobilized electrically charged biomolecules such as bacteria. The process is normally carried out in ammonia‐ or phosphate‐buffered saline and monitored in situ to reveal photoluminescence (PL) intensity maximum (PL max ) when the photocorrosion front crosses the GaAs‐AlGaAs interface. The temporal position of PL max plotted as a function of the concentration of surface‐immobilized biomolecules allows calibration of the process and detection of unknown concentrations of bacteria. Successive employment of numerous GaAs‐AlGaAs interfaces in a stack of GaAs/AlGaAs quantum wells (QWs) for biosensing is drastically restricted due to the diminishing PL intensity related to accumulation of Al oxides and other byproducts on the surface of processed samples. Herein, the application of a cyclic injection of NaOH solution for chemical “sweeping” of the AlGaAs surface to maintain a sustainable DIP process manifested by nonvanishing amplitude of the PL signal is reported. The successful measurement of eleven PL max with comparable amplitudes from the same GaAs/AlGaAs QW microstructure paves the way to the development of an advanced biochip delivering a large number of data points