Portail des publications scientifiques IMT Mines Alès
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Purpose in life and lung function: an individual-participant meta-analysis of six cohort studies
No full textInternational audienc
Maîtrise des Interactions Rayonnement-Matière et transferts énergétiques lors de la fabrication par SLS de composites polymères particulaires
No full textThe goal of the thesis project is to widen the range of compositions of polymer materials that can be transformed by Selective Laser Sintering (SLS), specifically particulate and flame retarded composites based on polyamides 12, and to evaluate the influence of the addition of inorganic micronic particles on the laser-matter interaction and on the heat transfer to the polymer particles. The understanding of laser-powder energy interactions, via their characterization and modeling, is the major issue of this thesis, with a view to ensure the feasibility of producing complex multi-component compositions applicable to technical parts (aeronautics, nautical, medical), in order to:-optimize mechanical properties and reaction to fire,-Improve the environmental impact of the process through its energy efficiency and the limitation of the non-recyclable fraction.L'objectif général du projet de thèse est de permettre d'élargir l'éventail des compositions de matériaux polymères pouvant être transformées par Selective Laser Sintering (SLS) et notamment des composites particulaires et/ou ignifugés basés polyamides 12, ainsi qu'évaluer l'influence de l'ajout de particules microniques inorganiques sur l'interaction laser matière ainsi que sur le transfert de chaleur vers les particules de polymère. La compréhension des interactions énergétiques laser-poudres, via leur caractérisation et leur modélisation, est la problématique majeure de cette thèse, en vue d'assurer la faisabilité de réalisation de compositions complexes multi-composants applicables à des pièces techniques (aéronautique, nautisme, médical), afin de :- optimiser les propriétés mécaniques et les propriétés de réaction au feu,- améliorer l'impact environnemental du procédé à travers son efficacité énergétique et la limitation de la fraction non recyclable
Restoring the complexity of walking in the elderly and its impact on clinical measures around the risk of falls
No full textInternational audienceIntroduction: The hypothesis of the loss of complexity with aging and disease has received strong attention. Especially, the decrease of complexity of stride interval series in older people, during walking, was shown to correlate with falling propensity. However, recent experiments showed that a restoration of walking complexity in older people could occur through the prolonged experience of synchronized walking with a younger companion. This result was interpreted as the consequence of a complexity matching effect. Experiment: The aim of the present study was to analyze the link between the restoration of walking complexity in older people and clinical measures usually used in the context of rehabilitation or follow-up of older people. Results: We evidenced a link between restoring complexity, improving overall health and reducing fear of falling. In addition, we showed that 3 weeks of complexity matching training can have a positive effect on complexity up to 2 months post-protocol. Finally, we showed that the restoration of walking complexity obtained in the previous works is not guide-dependent
A Review of Human Synchronization Datasets
No full textInternational audienceHuman synchronization refers to the coordination in time of individuals’ actions, movements, or physiological processes, often considered within a rhythmical context. This phenomenon can occur in various forms such as matching rhythmic movements, aligning speech patterns, or synchronizing biological rhythms. It plays a crucial role in social interactions, effective communication, sports, and musical performance. This work aims to reference accessible online datasets related to human synchronization, to increase their visibility and availability. Notably, it compiles 75 directly accessible datasets and 26 with indirect access to study synchronization in various contexts. It reviews all types of synchronization tasks and contexts found in the datasets. Results are clustered into four categories: discontinuous movement, continuous movement, social interactions, and musical performance. Then, this review explores the signals and acquisition methods used across human synchronization datasets, ranging from simple touchpads, and kinematic sensors, to expansive motion capture and hyperscanning technologies. This paper surveys objective measures of synchronization used in the gathered papers and reveals some heterogeneity in the quantification of synchronization. Furthermore, it points out a lack of annotated datasets, which limits the development of machine learning methods. By compiling accessible datasets, this review centralizes valuable experimental data, providing a foundation for more collaborative, comprehensive, and standardizedapproaches to studying human synchronization
Fire Behavior of Biobased Concretes: Experimental and Numerical Approach
No full textNational audienc
Negative First Impression of a Schizophrenia Patient Based on Thin Slice of Social Behavior
No full textInternational audienceIndividuals diagnosed with schizophrenia encounter significant challenges in their daily social interactions. These deficits emphasize neurocognitive disabilities, impaired social cognition, and stigma. However, social presentation especially public perception of patients’ social behavior has been poorly studied to date in this mental disorder despite the fundamental importance of first impression in human interaction. This study aims to investigate whether a schizophrenia patient leads to a lower first impression than a depressive individual and a healthy control when there is no diagnostic label, and on which features these first impressions are created. We extracted nonverbal behavioral measures from thin slice of social behaviour of the stimulus participants and presented audio and/or video clips to naive observers. We found that the general population had significantly more negative impressions and behavioral intentions to interact with the schizophrenia patient than the depressive and the control participant, regardless of the modality presented. As patients displayed fewer nonverbal behaviors, it suggests that social behavior drives first impression in schizophrenia. Such findings may lead to new ways of developing intervention programs targeting motor nonverbal behavior, leading to reduce social rejection in these populations
Boosting photosynthesis opens new opportunities for agriculture sustainability and circular economy: The BEST ‐ CROP research and innovation action
No full textInternational audienceThere is a need for ground‐breaking technologies to boost crop yield, both grains and biomass, and their processing into economically competitive materials. Novel cereals with enhanced photosynthesis and assimilation of greenhouse gasses, such as carbon dioxide and ozone, and tailored straw suitable for industrial manufacturing, open a new perspective for the circular economy. Here we describe the vision, strategies, and objectives of BEST‐CROP, a Horizon‐Europe and United Kingdom Research and Innovation (UKRI) funded project that relies on an alliance of academic plant scientists teaming up with plant breeding companies and straw processing companies to use the major advances in photosynthetic knowledge to improve barley biomass and to exploit the variability of barley straw quality and composition. We adopt the most promising strategies to improve the photosynthetic properties and ozone assimilation capacity of barley: (i) tuning leaf chlorophyll content and modifying canopy architecture; (ii) increasing the kinetics of photosynthetic responses to changes in irradiance; (iii) introducing photorespiration bypasses; (iv) modulating stomatal opening, thus increasing the rate of carbon dioxide fixation and ozone assimilation. We expect that by improving our targeted traits we will achieve increases in aboveground total biomass production without modification of the harvest index, with added benefits in sustainability via better resource‐use efficiency of water and nitrogen. In parallel, the resulting barley straw is tailored to: (i) increase straw protein content to make it suitable for the development of alternative biolubricants and feed sources; (ii) control cellulose/lignin contents and lignin properties to develop straw‐based construction panels and polymer composites. Overall, by exploiting natural‐ and induced‐genetic variability as well as gene editing and transgenic engineering, BEST‐CROP will lead to multi‐purpose next generation barley cultivars supporting sustainable agriculture and capable of straw‐based applications
Analog modeling of landslide dynamics: Case study from the Andean Mesón Alto deposit, Central Chile (∼33°40′S)
No full textInternational audienceThe Mesón Alto deposit in the Central Chilean Andes (∼33°40′S) is a large-volume rock avalanche deposit (∼4.5 km3) formed in a glacial valley, presenting four distinct lithological bands whose origin is uncertain. This study employs analog modeling to investigate the influence of different kinematic variables on the deposit characteristics of landslides inspired in the Mesón Alto deposit. Field mapping has identified two primary lithological groups in the Mesón Alto deposit: andesitic fragments from the Oligo-Miocene formation and Miocene granodioritic rocks. The deposit displays a complex distribution of materials, including areas with well-sorted and poorly sorted deposits and varying grain sizes, from very large blocks to a locally significant presence of fine sediments. We developed analog models using a custom device that simulates the fluvial and glacial valley topography, varying factors such as valley geometry (U- or V-valley), opposite slope angles, and the number and proportion of landslide events. The measured parameters for comparisons included the deposit's width, length, and vertical and horizontal distances from the landslide crown to the toe. Our results highlight that variations in valley geometry and the number of events significantly influence the observed deposit structure. The study's findings provide insights into the dynamics of large-volume landslides and contribute to understanding the Mesón Alto deposit's formation. Results suggest that its complexity is primarily driven by a combination of geomorphological factors and the number of rock avalanche events: U-valley in confined conditions and two events, with the first larger than the second (70 %–30 %). Our results shed light on the processes shaping the Mesón Alto deposit and offer a framework for interpreting similar deposits in other glacial valleys worldwide, enhancing our understanding of variables that potentially influence the distribution and characteristics of landslide deposits in diverse settings
Etude expérimentale, numérique et CFD de l'onde de surpression en champ proche et la charge au sol résultant d'une explosion de type BLEVE ( Boiling Liquid Expanding Vapour Explosion)
No full textA BLEVE, or Boiling Liquid Expanding Vapor Explosion, is a complex thermomechanical phenomenon that occurs when a pressure liquefied gas – such as propane, ammonia, or hydrogen – undergoes rapid phase change due to containment failure. This two-phase physical explosion can arise during severe accidents involving the storage, transportation, or handling of such pressurized substances. BLEVEs are particularly dangerous due to their sudden and violent nature, often resulting in human casualties and extensive property damage. Understanding the underlying mechanisms and associated hazards is therefore crucial to tackle and bridge knowledge gaps and enhance safety procedures.This thesis provides a comprehensive investigation of BLEVE phenomena through experimental, numerical, and computational approaches. The work focuses on key aspects of the explosion process, including near-field aerial shock overpressure, boiling dynamics, vessel rupture and opening behavior, and ground loading effects. A wide range of small-scale experiments (70) were done using aluminum tubes, varying parameters such as failure pressure, liquid fill level, and weakened length. These variations allowed for an in-depth analysis of BLEVE causes and the severity of its related hazards.The research introduces new knowledge on compressed liquid BLEVEs (100 % liquid full), and numerical correlations based on semi-empirical models to estimate the near-field shock overpressure and ground load forces. The work investigates the critical role of vessel opening dynamics on the hazard’s intensity and improves the definition of BLEVE, along with a clearer identification of the specific conditions under which it is likely to occur. High-speed imaging validated theoretical models and offered visual insights into the internal and external dynamics involved in a BLEVE. The study has investigated both internal and external dynamics of BLEVE events, especially the role of liquid and vapor phases, contributing new knowledge to the field. Furthermore, computational simulations enabled the analysis of internal fluid behavior and external blast propagation, not easily observable through experiments alone.The relevance of this research lies in its ability to not only confirm current knowledge but also to extend the understanding of BLEVE, which has direct applications to risk assessment and hazard mitigation.BLEVE, ou Boiling Liquid Expanding Vapor Explosion , est un phénomène thermomécanique complexe qui se produit lorsqu'un liquide sous pression – tel que le propane, l'ammoniac ou l'hydrogène – subit un changement de phase rapide à la suite de la rupture de son confinement. Cette explosion physique diphasique se produit lors du stockage, du transport de ces substances sous pression. Les BLEVE sont particulièrement dangereux en raison de leur nature soudaine et violente, entraînant souvent de graves pertes humaines et d'importants dégâts matériels. La compréhension des mécanismes multidisciplinaires sous-jacents et des risques associés est donc essentielle pour combler les lacunes dans les connaissances et améliorer les procédures de sécurité.Cette thèse propose une étude approfondie du phénomène par des approches expérimentales, numériques et CFD. Les travaux se concentrent sur les aspects clés, notamment la surpression due aux chocs aériens en champ proche, la dynamique de l'ébullition, la dynamique de rupture du récipient, et les effets de la charge au sol. Un large nombre d'expériences (70) a été réalisé, faisant varier des paramètres tels que la pression de rupture, le niveau de remplissage du liquide et la longueur de l'élément affaibli. Ces variations ont permis une analyse des causes du BLEVE et de la gravité des risques associés.Cette recherche apporte de nouvelles connaissances sur les BLEVE à liquide comprimé, ainsi que des corrélations numériques basées sur des modèles semi-empiriques pour estimer l’onde de choc et la charge au sol. Elle étudie le rôle de la dynamique d'ouverture du récipient sur l'intensité des risques et améliore la définition du BLEVE, tout en identifiant les conditions nécessaires. Les cameras rapides ont permis de valider les modèles théoriques et ont fourni un aperçu visuel des dynamiques internes et externes impliquées dans un BLEVE, en particulier le rôle des phases liquide et vapeur, apportant ainsi une nouvelle expertise dans le domaine. De plus, les simulations CFD ont permis une analyse approfondie. L'intérêt de cette recherche réside dans sa capacité non seulement à confirmer les connaissances actuelles, mais aussi à approfondir la compréhension du BLEVE, ce qui a des applications directes à l'évaluation des risques et à la réduction des dangers
Teaching Machines to Understand Water: Adapting AI to Hydrosystem Complexity
No full textInternational audienceArtificial intelligence is most often used for problems where the data is digital from the outset (internet audience, Netflix, etc.) and where the stakes associated with errors are low. However, the opposite is true for hydrosystems: natural data is fraught with uncertainty and is imperfectly digitised. The systems to be described are complex (non-linear, non-stationary) and associated with high stakes (floods, low water levels). In this context, what precautions should be taken to use AI methods effectively