Portail des publications scientifiques IMT Mines Alès
Not a member yet
5198 research outputs found
Sort by
Enhancing Flame Retardancy of Flax Fabrics through Phytic Acid Grafting
No full textInternational audienceFlame-retardant flax fabrics were developed using the grafting of phytic acid (PA) through a two-step process. First, flax fabrics were functionalized with glycidyl groups employing the polymerization of glycidyl methacrylate (GMA) via a simultaneous e-beam irradiation procedure. Subsequently, the modified flax fabrics were treated with PA using two different techniques: the first method involved a direct grafting approach, where the phosphonic functions of PA reacted with the glycidyl groups. The second technique employed a coating process, which was based on a combination of PA and ethylene glycol diglycidyl (EGDG) as a curing agent, producing a phosphonated layer on the flax fibers. The treatment processes were applied to pristine and alkali pretreated flax fabrics, allowing an investigation into the impact of delignification and PA grafting on burning behavior. SEM-EDS, 13C and 31P solid NMR, and FTIR were used to characterize the treatment process steps. Thermogravimetric analysis (TGA), pyrolysis combustion flow calorimetry (PCFC), and cone calorimetry tests were performed to evaluate the pyrolysis and combustion behaviors of prepared samples. The treated flax fabrics exhibited a good flame-retardant property only at 1.3 wt % of P content, while for a lower content, it was not effective enough. Moreover, the delignification of the flax fabric contributed significantly to enhance its fire behavior
QAI-Sport project : characterization of Indoor Air Quality in sports facilities
No full textInternational audienceIndoor air quality in sports facilities is still poorly studied compared to that of housing and other public buildings. One objective of the QAI-Sport project consisted in providing an overview of the organic chemicals and microbiological composition in air of 10 sports halls having different activities: dojos, motricity rooms and weight rooms. Targeted and non-targeted analytical approaches were applied to provide the broadest possible screening of VOCs, SVOCs and microbiological contaminants in indoor air and settled dusts (for SVOCs) with a focus on emerging pollutants. Two sampling campaigns were performed in unoccupied and occupied rooms to assess the impact of sporting activity on IAQ.For VOCs, active sampling using various supports was applied: Carbograph 4 cartridge, 2,4-dinitrophenylhydrazine cartridge for carbonyls and bubbling solution for carboxylic acids. Analyses were carried out by ATD-GC-MS, HPLC-UV and ion chromatography, respectively. Indoor air SVOCs were sampled on cartridge containing polyurethane foam and quartz filter to determine the total concentration (gas + suspended particles) of about forty compounds. Samples were analyzed by GC/MS/MS after pressurized solvent extraction (PLE). Settled dust were collected by vacuum cleaner in occupied rooms and sieved to 100 μm before PLE and GC/MS/MS analysis. For microbiological contaminants, air was sampled by cyclonic collector in liquid medium and analyzed by culture (bacteria and molds identification) and molecular biology (PCR) for viruses, including Sars-Cov-2.About 50 VOCs were identified and quantified. Composition and concentrations are globally close to those of other indoor environments, with a predominance of carbonyls, especially hexanal. However, some specific and emerging compounds (like benzothiazole, decamethylcyclopentasiloxane and 1-(2-methoxy-1-methyl ethoxy)-2-propanol)) were highlighted. Acetone and 6-methyl-5-hepten-one, emitted by human body, were identified as occupancy tracers. SVOCs are mainly phthalates (DiBP, DBP in air, DEHP, DiNP in dust), organophosphate flame retardants (TCPP in air, EHDPP, TPP in dust) and PAHs (Fluorene, phenanthrene in air, pyrene in dust) which concentrations are particularly high in one weight room’s dust, probably issued from a recycled rubber flooring. Microbiological contamination is similar to residential ones and Sars-CoV-2 was not detected. The project will further consist in identifying pollutants’ sources, understanding their partitioning indoors and assessing exposure
Digital Integration of AI and Simulation in the Airbus Helicopters Production System
No full textInternational audienc
Etude expérimentale de la propagation du front de flamme lors d’une explosion de poussières combustibles
No full textDust explosions represent a significant hazard in industries, with both organic and metallic dusts posing unique challenges due to their combustible nature. Among these, aluminum dust is particularly concerning due to its reactivity and combustion characteristics. Understanding the dynamics of dust explosions is critical for improving safety protocols and preventing catastrophic events. knowledge regarding dust explosions, particularly those involving metallic powders, remains limited, largely due to the complexities involved in experimental studies.This work focused on the experimental investigation of flame propagation mechanisms in aluminum dust suspensions. The research aimed to deepen the understanding of dust explosion dynamics by providing significant experimental data that could refine and validate predictive models for these phenomena. The study was structured in two main parts.In the first part, an experimental setup was developed, while incorporating advanced optical techniques, such as Time-Resolved Particle Image Velocimetry (TR-PIV) and direct flame visualization. These techniques facilitated accurate measurements of flame front characteristics and flow dynamics, enabling the determination of both flame propagation velocity and local burning velocity.The study's second part analyzed the effects of particle size and concentration on flame propagation. It found that smaller aluminum particles (6 μm) resulted in higher flame propagation velocities and burning velocities compared to larger particles (20 μm), highlighting the influence of particle size on combustion behavior. While turbulence levels did not exceed 10%, a clear relationship was highlighted between turbulence intensity and burning velocity, with the increase in burning velocity being more pronounced for the smaller particles.Les explosions de poussières représentent un danger majeur dans divers secteurs industriels, avec des défis spécifiques posés tant par les poussières organiques que métalliques en raison de leur nature combustible. Parmi celles-ci, la poussière d’aluminium est particulièrement préoccupante en raison de sa réactivité et de ses caractéristiques de combustion. La compréhension des dynamiques des explosions de poussières est essentielle pour améliorer les protocoles de sécurité et prévenir les catastrophes. Les connaissances sur les explosions de poussières, en particulier celles impliquant des poudres métalliques, restent limitées, principalement en raison des complexités liées aux études expérimentales.Ce travail s’est concentré sur l’investigation expérimentale des mécanismes de propagation des flammes dans les suspensions de poussière d’aluminium. L’objectif de la recherche était d’approfondir la compréhension des dynamiques d’explosion de poussières en fournissant des données expérimentales significatives permettant d’affiner et de valider les modèles prédictifs de ces phénomènes. L’étude s’articule autour de deux parties principales.Dans la première partie, un dispositif expérimental a été développé, en intégrant des techniques optiques avancées, telles que la vélocimétrie par image de particules à résolution temporelle (TR-PIV) et la visualisation directe des flammes. Ces techniques ont permis de mesurer avec précision les caractéristiques du front de flamme et les dynamiques d’écoulement, facilitant ainsi la détermination à la fois de la vitesse de propagation de la flamme et de la vitesse de combustion locale.La deuxième partie de l’étude a analysé les effets de la taille et de la concentration des particules sur la propagation des flammes. Il a été constaté que les particules d’aluminium plus petites (6 μm) entraînaient des vitesses de propagation des flammes et de combustion plus élevée que les particules plus grosses (20 μm), soulignant l’influence de la taille des particules sur le comportement de la combustion. De plus, les particules plus petites ont généré une intensité de turbulence presque quatre fois supérieure, bien que l’impact de la concentration de poudre sur la turbulence reste incertain. Bien que les niveaux de turbulence n’aient pas dépassé 10%, une relation claire a été observée entre l’intensité de la turbulence et la vitesse de combustion, l’augmentation de cette dernière étant plus marquée pour les petites particules
Contribution à la valorisation des ressources naturelles dans une perspective d’économie circulaire : exploration du concept de bioraffinage - mise en oeuvre de biocomposites émergents - comportement thermique, mécanique, interfaces, durabilité et feu
No full textThermo-Mechanical Analysis of a Stone Masonry Wall Subjected to Fire Using FEM and DEM Approaches
No full textInternational audienceThe DEMMEFI (Discrete Element Method, Finite Element Method, FIre) research project focuses on developing a numerical tool for post-fire diagnosis of stone masonry structures, with a particular interest in assessing the restoration feasibility for historic buildings like the Notre-Dame de Paris cathedral. This paper presents the validation process of micro-scale thermomechanical behaviour laws integrated into Finite Element Method (FEM) and hybrid FEM/Discrete Element Method (DEM) models, using experimental data from masonry walls subjected to thermal and mechanical loading. Through a methodology involving experimental data analysis, numerical simulations, and model refinement, the study evaluates the effectiveness of the ENDO3D (for 3D anisotropic damage) model in accurately predicting cracking schemes and deflection in masonry structures under fire conditions. Additionally, insights into the influence of key parameters on temperature propagation and out-of-plane deflection are discussed. The findings underscore the importance of these factors in numerical modelling, enabling further work to refine models and ultimately macro-scale simulations of stone masonry structures. This research contributes to advancing engineering practices for the preservation and restoration of cultural heritage sites constructed from stone masonry
Short-term investigation of interactions of plain concrete, marine microorganisms, and sea water for the application of Floating Offshore Wind Turbines (FOWTs)
No full textInternational audienceFOWTs operate in deep waters. A durable concrete cover in the submerged zone is critical in immersed components because it prevents the transport of aggressive ions, and thus protects the reinforcement from corrosion. The aim of this interdisciplinary study is to identify the surface interactions between cementitious materials, biofouling at their surface, and seawater with emphasis on, (i) the influence of the material on the composition and structure of biofilm, and (ii) the influence of biofilm and seawater on mineralogical and chemical changes within cementitious matrix. Mortars and concrete are prepared using two low-CO2 binders incorporating supplementary cementitious materials, CEM III and CEM V, as well as a conventional binder, CEM I. The specimens were submerged at a depth of 27m at SOLA station, Banyuls-sur-mer, France. Biofouling was characterized using Environmental Scanning Electron Microscope (ESEM) and environmental DNA analysis, whilst, microstructure, mineralogical, and chemical changes in cementitious materials were determined using SEM coupled to Energy Dispersive Spectroscopy (SEM-EDS), X-Ray Diffraction (XRD), and Electron Probe Micro Analysis (EPMA) respectively. Our results suggest that irrespective of the binder-type and age, earlyage exposure (after 30- and 90 days) leads to the precipitation of calcium carbonate, mainly in the form of aragonite at seawater/biofilm-concrete interface. EPMA findings on CEM I concrete indicate calcium leaching and Mg-precipitate on the outer layers. After three months, sulfur-rich and chloride-rich zones followed the Mg-rich zone. The microbial diversity in marine biofilms was determined as a function of binder-type, the differences in composition fading over time on concrete surface
Evaluation des impacts environnementaux du recyclage de lames de terrasse en composite bois/plastique par analyse de cycle de vie.
No full textInternational audience536674ACV ; recyclage ; composite bois/plastiqueEvaluation des impacts environnementaux du recyclage de lames de terrasse en composite bois/plastique par analyse de cycle de vie.4191
Towards the Automated Analysis of Expressive Gesture Qualities in Full-Body Movement: The Perceived Origin of Movement
No full textInternational audienceThe automatic detection of the perceived origin of full-body human movement (OoM), i.e., of the part of the body that an external observer perceives as the joint where the movement originates, is a relevant topic for human movement analysis, as it can allow one to interpret affective content and social signals and can have applications in cognitive/motor rehabilitation, among others. Within this framework, the objective of this work is to present a computational method aimed at the automatic detection of the perceived OoM, starting from movement features acquired via motion capture techniques. After defining the concept of perceived OoM, the following contributions are presented: a set of techniques for the automated analysis of full-body expressive non-verbal communication, based on several low-level local movement features of the joints (speed, tangential acceleration, angular momentum); a computational method for the automatic detection of the perceived OoM at different spatial scales; and a repository of full-body movements annotated in terms of the perceived OoM, adopted for validation and evaluation of the method. The results of the analysis demonstrate its effectiveness. Finally, possible extensions of the method are outlined
Effect of Accelerated Aging Weathering on Fire and Mechanical Properties of Plywood
No full textInternational audienceThis study is focused on the impact of aging on the fire and mechanical behavior of a fire-retarded industrial plywood claimed for outdoor use as cladding. Two sets of okoume-based (Aucoumea klaineana) plywood, with and without flame retardant, were examined: one aged 4 weeks by immersion in hot water (40 ℃), and the second aged with artificial UV light coupled to spraying for 12 weeks. Scanning electron microscopy coupled with EDX analysis were used to investigate changes in the material after aging, and distribution of flame retardant in the material. This study reveals the impact of different aging procedures on the physico-chemical modifications of the composite material. In addition, the mechanical properties of aged plywood were measured by static bending tests and vibration analysis as non-destructive method to assess weekly the aging effect. Thus, the fire behavior of the sets of plywood as a function of aging exposure time was evaluated by cone calorimetry. The results show that, whatever the aging, it occurs a microstructural degradation of wood and a fast leaching of the flame retardant in whole wood plies, especially for immersion aging. The mechanical properties are then reduced and the fire retardancy is quickly ineffective after aging