HAL Portal UTC Université de Technologie de Compiègne
Not a member yet
11652 research outputs found
Sort by
Adoprivacy - La faible prise de conscience des enjeux des stratégies des plate-formes numériques
No full textInternational audienceLa connaissance des droits et des enjeux des données personnelles sur les plateformes est très inégalement appropriée par les adolescents.Le contexte social, l’âge, le genre, la formation sont des facteurs discriminants. Pour les enseignants et les éducateurs, les questions sont également particulièrement complexes. Les enseignants ont peu de créneaux horaires réservés à la transmission de ces connaissances, et peu de formations pour les acquérir.L’utilisation croissante de la géolocalisation sociale par les adolescents et leurs parents participe au brouillage des enjeux de surveillance.La table ronde permettra d’exposer les résultats de l’équipe Adoprivacy, d’ouvrir sur les enjeux des littératies numériques, c’est à dire la transmission d’un ensemble de compétences numériques, dans leur diversité (litteratie de la privacy, litteratie de la surveillance, litteratie de la data) et de tisser des comparaisons européennes
Modeling the acoustic radiation of plates using circular pistons
No full textInternational audienceEquivalent piston model Average radiation efficiencyMean radiated power Complex-shaped plates Tetris plates Hear the shape of a drum A B S T R A C TWe propose an equivalent piston model (EPM) for estimating the modal radiation efficiency of complex-shaped plates. In this model, the structure is not discretized into small elementary radiators. Instead, it involves determining the minimum number, size, volume velocity, and position of vibrating pistons that radiate in accordance with the mode shape they emulate, i.e. one piston per lobe within the mode shape, regardless the plate's shape. For shapes relatively close to rectangles, a specific version of the method is proposed by representing the shape only by two characteristic lengths (EPM-RD), and paving the virtual surface with pistons vibrating at alternate phases along a rectangular grid. The validity of this assumption is evaluated in terms of shape dissymmetry, which can cause residual radiators to appear, and where the dissymmetry can affect the spatial distribution of lobes. With a known spatial distribution mimicking the mode shapes, it is possible to estimate also average values of radiation parameters, such as the average radiation efficiency and time-average mean power. The average radiation efficiency and power follow the Equipartition Theorem and allow the calculation to be performed without cross-terms and using only the modal efficiencies and resonance frequencies. Due to their simplicity and ease of implementation, piston-based equivalent models have great potential for solving radiation problems from flat structures. Any mode shape can be modeled with vibrating pistons and analytical formulations can be easily derived, even for complex geometries. Moreover, with EPM-RD, average values can also be calculated, which provides an estimation of average radiated properties within seconds without requiring any integration or large matrices to be solved.</div
1-ethyl-3-methyl imidazolium acetate, hemicellulolytic enzymes and laccase-mediator system: Toward an integrated co-valorization of polysaccharides and lignin from Miscanthus
No full textInternational audienceThe pretreatment of Miscanthus x giganteus with the ionic liquid 1-ethyl-3-methylimidazolium acetate ([Emim] [OAc]), followed by enzymatic hydrolysis and oxidative depolymerization, resulted in the efficient production of monomeric sugars and selective production of phenolic intermediates. The liquid fractions containing monomeric sugars were obtained with high yields (>80%), while a solid fraction enriched with lignin (>50% w.w − 1) was isolated. The phenolic monomers released during [Emim][OAc]-pretreatment were identified and quantified by HPLC. A decrease in the content of vanillin, vanillic acid, and p-hydroxybenzaldehyde was observed during pretreatment, suggesting a selective solubilization of guaicyl and p-hydroxyphenyl units from the lignin polymer in [Emim][OAc]. The decrease in p-coumaric and ferulic acids content suggested a cleavage of lignincarbohydrate complexes during pretreatment. Both pretreatment and enzymatic hydrolysis affected the content of ferulic acid ether and ester bonds. The NMR structural study (2D HSQC) of the isolated lignin showed the preservation of β-O-4 ′ interunit bonds, while 31 P NMR analysis revealed a high content of aliphatic hydroxyl groups. The oxidative depolymerization of the isolated lignin, catalyzed by the laccase mediator system in the presence of 5% v.v − 1 recycled [Emim][OAc] in buffer, mainly led to the production of free p-hydroxybenzaldehyde as a promising platform molecule. The mass balance of glucan, xylan and lignin from Miscanthus was validated throughout this strategy
Free and Bound Phenolic Profiles and Antioxidant Activities in Melon (Cucumis melo L.) Pulp: Comparative Study on Six Widely Consumed Varieties Planted in Hainan Province
No full textInternational audienceBound phenolic compounds in the melon pulp have seldom been investigated. This study revealed considerable differences in the total phenolic content (TPC) and antioxidant activity of the free and bound phenolic extracts in the pulps of six melon varieties from Hainan Province, China. Naixiangmi and Yugu demonstrated the highest free TPC, while Meilong showed the highest bound and total TPC and antioxidant activity. UHPLC-QQQ-MS identified and quantified 30 phenolic compounds. The melon cultivars markedly differed in the amount and content of their free and bound phenolic compounds. Xizhoumi No. 25 and Meilong afforded the most phenolic compounds. Hongguan emerged with the highest free phenolic compound content and total content of phenolic compounds; however, Meilong possessed the highest bound phenolic compound content. Hierarchical cluster analysis divided the melon varieties into four different taxa. The present study provides a scientific basis for developing the health-promoting effects of melon pulp
Combining Differential Interferometry and Reverberation Mapping for AGN in the J band: (with some inputs from L, M, N, H…)
No full textInternational audienceSpectro Astrometry (SA) from phase differential interferometry has proven to provide a measure of the mass of the Super Massive Black Hole at the heart of an AGN from a super resolution of its BLR. SARM that combines the SA angular measures with the Reverberation Mapping (RM) linear information yields additional constraints on the SMBH mass and direct distance measurements with a possible contribution to the Hubble tension problem. However, the model fits of SA and RM, alone as well as combined in SARM are sensitive to parameter degeneracies due to the unknown geometry of the BLR, resulting in a loss of accuracy of the mass and distance measurements. We show that this accuracy can be improved by adding additional geometrical information, indirectly from the observation of the inner dust structure and directly from amplitude differential interferometry of the BLR that measures the variations of visibility or coherent flux trough the emission line. With the current optical interferometers, amplitude differential interferometry of the BLR would be accessible (only) at the VLTI in the J band. The J band has the additional major advantage that it allows a much larger sample of BLR combining high accuracy SA and Reverberation Mapping with reasonable time spans. We discuss the feasibility of such a J band instrument with its specific fringe tracker, the impact on the number of accessible targets and the gain in precision and accuracy that would be offered by the J band on the VLTI
Modélisation multi-échelle des propriétés mécaniques passives du muscle squelettique murin : application à l’étude de l’expression du gène Klf10
No full textThe skeletal muscle is a complex organ with a hierarchical structure. Its behavior at the macroscopic scale (complete muscle) derives from the behavior of its various components on microscopic (muscle fibers) and submicroscopic (myofilaments, sarcomeres, etc.) scales. All its morphological and mechanical properties derive from a set of gene expressions which, if inhibited, can lead to deficiency or even pathological muscle behavior. This is the case of Klf10, present in muscle metabolism, whose involvement in the mechanical and morphological properties of other soft tissues has been demonstrated. In order to study the implication of this gene on muscle biomechanics, and more specifically during its inhibition, the first stage of this thesis consists in the experimental characterization of the mechanical properties of skeletal muscle at different scales: microscopic scale is represented by muscle fiber and macroscopic scale is represented by complete muscle. The study was carried out on two types of muscles: slow oxidative soleus and fast glycolytic EDL, on healthy (WT) and Klf10 gene inhibited (Klf10 KO) genotypes. This first stage of characterization shows differences in mechanical properties between slow-oxidative soleus and fast-oxidative EDL muscles, both microscopically and macroscopically. In parallel, the comparison between WT and Klf10 KO genotypes shows a variation in mechanical properties at microscopic scale for both muscle types, which is not present at macroscopic scale. Besides muscle fibers, the extracellular matrix (ECM) is an important component of skeletal muscle. To date, its mechanical characterization remains complex due to the lack of data in the literature and experimental protocols for studying its mechanics. To overcome this problem, we are developing a multiscale model dissociating the muscle into a muscle fiber part and an ECM part, represented by a hyperelastic, anisotropic and incompressible behavior law. The mechanical parameters of this behavior law are identified for the fiber part on the basis of experimental results obtained on isolated fibers, before the mechanical parameters of the ECM part are identified on the basis of those obtained on complete muscles by fixing the fiber parameters. The multiscale behavior law and mechanical parameters for fibers and ECM are then implemented in a finite element model to model microscopic and macroscopic skeletal muscle behavior for soleus and EDL muscles, in WT and Klf10 KO genotypes. The results of the muscle fiber and whole muscle modeling show good correspondence with experimentally obtained behavior. These models are followed by a parametric study of physiological parameters such as volume fractions, preferential orientations of muscle fibers, preferential orientations of collagen fibers in the ECM, as well as incompressibility in order to study their implication in overall muscle behavior. This parametric study highlights the importance of the ECM in the overall behavior of muscle through significant changes in the mechanical response of the numerical model when the preferential orientation parameter of collagen fibers in the ECM is varied, as well as when volume fractions are varied.Le muscle squelettique est un organe complexe avec une structure hiérarchisée. Son comportement à l’échelle macroscopique (muscle complet) découle du comportement de ses différents composants aux échelles microscopique (fibres musculaires) et submicroscopique (myofilaments, sarcomère, etc.). Toutes ses propriétés morphologiques et mécaniques découlent d’un ensemble d’expressions géniques qui, inhibées, peuvent entrainer des comportements défaillants voir pathologiques du muscle. C’est le cas de Klf10, présent dans le métabolisme du muscle et dont l’implication sur les propriétés mécaniques et morphologiques d’autres tissus mous a été démontrée. Dans le but d’étudier l’implication de ce gène sur la biomécanique du muscle, et plus particulièrement lors de son inhibition, la première étape de cette thèse consiste en la caractérisation expérimentale des propriétés mécaniques du muscle squelettique à différentes échelles : microscopique représentée par la fibre musculaire et macroscopique représentée par le muscle complet. Cette étude est faite sur deux types de muscles : soléaire oxydatif lent et EDL glycolytique rapide, sur des génotypes sain (WT) et dépourvu du gène Klf10 (Klf10 KO). Cette première étape de caractérisation montre des différences de propriétés mécaniques entre les muscles soléaires lents et EDL rapides autant à l’échelle microscopique que macroscopique. En parallèle, la comparaison entre les génotypes WT et Klf10 KO montre une variation des propriétés mécaniques à l’échelle microscopique pour les deux types de muscles, qui n’est cependant pas présente à l’échelle macroscopique. En parallèle des fibres musculaires, la matrice extracellulaire (MEC) est une composante importante du muscle squelettique. Sa caractérisation mécanique reste à ce jour complexe du fait du manque de données dans la littérature et de protocoles expérimentaux permettant d’étudier sa mécanique. Afin de pallier ce problème, nous développons un modèle multi-échelle dissociant le muscle en une partie fibres musculaires et une partie MEC, représenté par une loi de comportement hyperélastique, anisotrope et incompressible. Les paramètres mécaniques de cette loi de comportement sont identifiés pour la partie fibres sur les résultats expérimentaux obtenus sur fibres isolées, avant que les paramètres mécaniques de la partie MEC ne le soient sur ceux obtenus sur muscles complets en fixant les paramètres de la fibre. La loi de comportement multi-échelle ainsi que les paramètres mécaniques pour les fibres et la MEC sont ensuite implémentés dans un modèle par éléments finis pour modéliser le comportement microscopique et macroscopique du muscle squelettique pour les muscles soléaires et EDL, en génotypes WT et Klf10 KO. Les résultats des modélisations des fibres musculaires et des muscles entiers montrent de bonnes correspondances avec les comportements obtenus expérimentalement. Ces modélisations sont suivies par une étude paramétrique des paramètres physiologiques tels que les fractions volumiques, les orientations préférentielles des fibres musculaires, les orientations préférentielles des fibres de collagène de la MEC, ainsi que d’incompressibilité afin d’étudier leur implication dans le comportement global du muscle. Cette étude paramétrique met en avant l’importance de la MEC dans le comportement global du muscle par des modifications importantes de la réponse mécanique du modèle numérique lors de la variation du paramètre d’orientation préférentielle des fibres de collagène de la MEC, ainsi que lors de la variation des fractions volumiques
Study of the mechanical properties of polymers reinforced with nanoparticles of adjustable size, shape and surface chemistry
No full textInternational audienc
Map-aided annotation for pole base detection
No full textInternational audienceFor autonomous navigation, high definition maps are a widely used source of information. Pole-like features encoded in HD maps such as traffic signs, traffic lights or street lights can be used as landmarks for localization. For this purpose, they first need to be detected by the vehicle using its embedded sensors. While geometric models can be used to process 3D point clouds retrieved by lidar sensors, modern image-based approaches rely on deep neural network and therefore heavily depend on annotated training data. In this paper, a 2D HD map is used to automatically annotate pole-like features in images. In the absence of height information, the map features are represented as pole bases at the ground level. We show how an additional lidar sensor can be used to filter out occluded features and refine the ground projection. We also demonstrate how an object detector can be trained to detect a pole base. To evaluate our methodology, it is first validated with data manually annotated from semantic segmentation and then compared to our own automatically generated annotated data recorded in the city of Compiègne, France. Erratum: In the original version [1], an error occurred in the accuracy evaluation of the different models studied and the evaluation method applied on the detection results was not clearly defined. In this revision, we offer a rectification to this segment, presenting updated results, especially in terms of Mean Absolute Errors (MAE)
The Impact of Missing Data on Heart Rate Variability Features: A Comparative Study of Interpolation Methods for Ambulatory Health Monitoring
No full textInternational audienceh i g h l i g h t s g r a p h i c a l a b s t r a c t • Real time HRV analysis of R-R time series with missing data. • Higher impact of interpolation on frequency domain features • Better RMSSD estimation without interpolation beyond 50% missing data. • Combination of different interpolation methods according to both missing values' percentage and targeted HRV features
The Importance of Individual Work in Collaborative Design Meeting: Impact on Design Tools and Methodologies
No full textInternational audienceThis paper demonstrates the importance of individual work in collaborative design meetings based on Granger' causality and discusses how this impacts design tools and methodologies. Based on Tucker's et al. CIAO model of globally collaborative work which allows distinguishing the main modes of interaction during a meeting, our research identifies the patterns or sequences of those interaction modes according to the Granger causality concept. Granger causality makes it possible to identify a temporal precedence of events without necessarily implying causality. The results show that individual work plays a key role in achieving collaborative work. However, other factors such as the nature of the meetings and the objectives pursued also influence the sequences of interaction of the different modes. These first results allow making recommendations on collaborative work methodologies and support mechanisms for collaboration. For instance, the ability of digital devices to facilitate the simultaneous individual work of participants in a collective space is a key factor and the ability to preserve sequences for individual work during a design meeting should be monitored to keep global efficiency. \textcopyright The Author(s), 2023. Published by Cambridge University Press