Portail des publications scientifiques IMT Mines Alès
Not a member yet
5198 research outputs found
Sort by
Inorganic and Nanoadditives for Biodiesel
No full textInternational audienceThe main factors driving research into the creation and application of renewable energy sources are concerns about climate change, rising oil prices, and the depletion of fossil fuel resources. Because the transportation industry is the largest emitter of pollutants into the atmosphere, biofuel is one of the renewable energy sources used by most nations. Because it is an environmentally friendly renewable resource with the potential to lower greenhouse gas emissions, biodiesel, defined as “a substitute for or an additive to diesel fuel that is generated from the oils and fats of plants and animals”, is seen as an attractive replacement for petroleum-based diesel fuel. Because it produces biodiesel more quickly than acid catalysis, heterogeneous base catalysis is favored. High surface area improves the physicochemical characteristics of fuel and reduces the emission of dangerous pollutants. The performance of an engine is enhanced with the addition of nanoadditives. Numerous nanoadditives and the methods used to prepare them are described in this chapter. Examples of nanoadditives include metal-based (metals, metal oxides, and metal alloys), antioxidants, oxygenated additives, and cetane number enhancers. Analyses are also presented of the performance and emission characteristics. Comprehensive studies on the characteristics of emissions and the combustion behaviour of diesel engines powered by biodiesel and blends, including nanoadditives, are also included. Additionally, consideration is given to the characteristics, efficiency, and emissions of diesel engines running on biodiesel and blends, including nanoadditives
Vers le Digital Thread grâce à l’ingénierie des Jumeaux Numériques basée Modèles
No full textNational audienceUn Jumeau Numérique en tant qu'image virtuelle, fidèle d'un système physique pour un usage spécifié par ses utilisateurs est un système complexe. Cependant, sa conception demeure un processus long, couteux, encore peu formalisé malgré l'émergence de documents normatifs. Par ailleurs, l'Ingénierie Système fourni un ensemble de processus et méthodes reconnus et standardisés pour l'ingénierie de systèmes complexes fortement contraints. L'Ingénierie Basée Modèle en est une extension mettant en avant le rôle crucial de la modélisation et donc des modèles pour la conception des systèmes. Les modèles sont également des éléments essentiels qui font émerger le concept de Digital Thread. Celui-ci se veut être le rassemblement de toutes des données, informations et connaissances issues de l'ensemble des activités qui émaillent la vie du système physique, depuis sa conception jusqu'à sa fin de vie ou sa réutilisation, en assurant leur traçabilité, en promouvant leur gestion et en permettant leur utilisation de manière plus naturelle. Cet article introduit les principes méthodologiques pour l'ingénierie des Jumeau Numérique dans un objectif d'exploration et de valorisation du Digital Thread
Interpretation of cumulative frequency distribution curves of groundwater levels can bring information about the hydrodynamic properties of a karstified aquifer
No full textInternational audienc
Interface Formation Mechanisms in Fibre Reinforces Thermoplastic Tapes
No full textInternational audienceComposite materials future relies on achieving lighter parts through integrating sustainable materials, with bio-based and/or circular materials in reinforced thermoplastics. To meet the requirements of various industrial applications, Poly Ether Ether Ketone (PEEK) and biodegradable PolyLactic Acid (PLA) matrices can be reinforced by reclaimed carbon fibers and biodegradable flax fibers. However, the mechanical behavior of composites is heavily influenced by the quality of the interface and the presence of defects and voids, this would imply a required control at the stage of composite manufacturing. Despite their significance, mechanisms governing interface and void formation at the microscales and mesoscales remain insufficiently explored and understood.The adhesion phenomena at the fiber / matrix interface depends on different properties of the constituents. The most influent ones still must be identified. Moreover, the effect of temperature should be considered since the polymer can be exposed to high temperatures during the interface formation. Furthermore, the crystallinity and the induced mechanical properties of the produced fiber / matrix interface will be studied.The DUINTACOS project aims to address this gap by allowing a deep understanding of interface formation in fiber-reinforced thermoplastic tapes, seeking to minimize micro voids, that is a requirement to obtain a high-quality composite structure
Direct determination of turbulent burning velocity during aluminum flame propagation: comparison to the classical open-tube method
No full textInternational audienceBurning velocity is a key parameter of main flame propagation models. However, its experimental determination while studying propagating dust flame is still challenging. In this work, aluminum flame propagation in a vertical tube is studied. Two aluminum powders with different particle size distributions with a median diameter of 6.2 and 20.7 μm are analyzed for different equivalence ratios with air. The main objective of this work is to compare the methods commonly used in the literature to determine the burning velocity in the case of propagating flames. One of these methods is based on the estimation of the thermal expansion coefficient. This article focuses first on the estimation of this coefficient and presents the limits of considering the adiabatic flame temperature for its estimation; this coefficient is here deduced from preliminary experiments presented in this article. As detailed in the paper, these methods have some limitations and are therefore compared with an innovative method based on a local direct determination of the burning velocity. This local method is based on the measurement of the unburned flow velocity just ahead of the propagating flame front by Time-Resolved Particle Image Velocimetry (TR-PIV). The methods commonly used in the literature mainly underestimate the burning velocity when compared with the local method. The local method is then used to study the influence of the particle size distribution and the equivalence ratio on the turbulent burning velocity. Firstly, we observe that the turbulent burning velocity increases while the flame is propagating in the vertical tube. Furthermore, the turbulent burning velocity with the 6-μm powder is higher than with the 20-μm powder
The impact of exercise on Alzheimer’s disease progression
No full textInternational audienceIntroduction: The preventive effects of chronic physical exercise (CPE) on Alzheimer's disease (AD) are now admitted by the scientific community. Curative effects of CPE are more disputed, but they deserve to be investigated, since CPE is a natural non-pharmacological alternative for the treatment of AD.Areas covered: In this perspective, the authors discuss the impact of CPE on AD based on an exhaustive literature search using the electronic databases PubMed, ScienceDirect and Google Scholar.Expert opinion: Aerobic exercise alone is probably not the unique solution and needs to be complemented by other exercises (physical activities) to optimize the slowing down of AD. Anaerobic, muscle strength and power, balance/coordination and meditative exercises may also help to slow down the AD progression. However, the scientific evidence does not allow a precise description of the best training program for patients with AD. Influential environmental conditions (e.g. social relations, outdoor or indoor exercise) should also be studied to optimize training programs aimed at slowing down the AD progression.Keywords: Alzheimer’s disease; Alzheimer’s disease progression; activity of daily living; cognitive function; exercise; physical activity; slowing-down effects
Casein‐based conjugates and graft copolymers. Synthesis, properties, and applications
No full textInternational audienceBiobased natural polymers, including polymers of natural origin such as casein, are growing rapidly in the light of the environmental pollution caused by many mass‐produced commercial synthetic polymers. Although casein has interesting intrinsic properties, especially for the food industry, numerous chemical reactions have been carried out to broaden the range of its properties, most of them preserving casein's nontoxicity and biodegradability. New conjugates and graft copolymers have been developed especially by Maillard reaction of the amine functions of the casein backbone with the aldehyde functions of sugars, polysaccharides, or other molecules. Carried out with dialdehydes, these reactions lead to the cross‐linking of casein giving three‐dimensional polymers. Acylation and polymerization of various monomers initiated by amine functions are also described. Other reactions, far less numerous, involve alcohol and carboxylic acid functions in casein. This review provides an overview of casein‐based conjugates and graft copolymers, their properties, and potential applications
A One-Step Approach for a Durable and Highly Hydrophobic Coating for Flax Fabrics for Self-Cleaning Application
No full textInternational audienceHighly hydrophobic flax fabrics with durable properties were prepared using the “dip-coating” method for self-cleaning application. Flax fabrics were coated with a polysiloxane coating via a hydrosilylation reaction with a Karstedt catalyst at room temperature. The coated fabrics displayed highly and durable hydrophobic properties (contact angle and sliding angle of about 145° and 23°, respectively) with good self-cleaning ability for certain pollutants and excellent durability. Moreover, the influence of the coating process on the mechanical properties of fabrics was investigated. A decrease in E modulus and an increase in tensile stress at maximum force and elongation at maximum force has been observed. Furthermore, this influence of the coating process can be easily controlled by adjusting the proportion of curing agent in the treatment solution
Origin of an intermediate peak in DMTA analysis of multilayer ABS/PC samples
No full textInternational audienceThree layers film shaped by thermocompression of acrylonitrile butadiene styrene copolymer and polycarbonate have been analyzed in dynamic mechanical thermal analysis in tensile mode. They present two peaks as the film is loaded perpendicularly to the layers and three peaks as the film is loaded in parallel to the layers. Numerical computations confirm that the origin of this peak is not related to a mechanical issue such as the transmission of the imposed deformation from one layer to the other. Using this method, it is demonstrated that this third peak can only be obtained assuming a material transition with its own behavior between layers. Tan δ measurements provide a simple and useful experimental tool to understand more about the interfacial zone in polymer blends
Recycled carbon fiber potential for reuse in carbon fiber/PA6 composite parts
No full textInternational audiencePyrolysis reclaiming is the most promising process to treat high volumes of composite waste with an advantageous carbon footprint. This paper aims to compare pyrolysis reclaimed carbon fibers (RCF) to virgin sized fibers (VF) and de-sized fibers (VFT) in their capability to bond to a polyamide 6 matrix. Micromechanical tensile testing of single fiber samples of the three fiber types was conducted. A minor reduction in tensile strength and an unchanged elastic modulus of the RCF compared to VF was observed. Scanning electron microscopy and atomic force microscopy scans were used to evaluate the morphology of the fibers. To evaluate the surface energy of the fibers, tensiometric testing was conducted. RCF showed a better adhesion capability compared to VFT through higher total surface energy. Moreover, X-ray spectrophotometry scans highlighted a higher proportion of functional groups at the RCF surface compared to VFT. Finally, pull-out tests underlined a decrease of the interfacial shear strength of RCF and VFT by 35 % compared to VF. Overall, this study’s results further the understanding of the impact of the pyrolysis reclaiming process on RCF mechanical and adhesion properties