Portail des publications scientifiques IMT Mines Alès
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Ignition of biobased concretes
No full textInternational audienceNowadays, the construction field is responsible for a quarter of French emissions of greenhouse gases. In order to minimize this impact, one solution is to promote the use of local and biobased materials with a low carbon impact. Biobased resources can be mixed with a binder to produce light (150 – 500 kg.m⁻³), medium (500 – 1200 kg.m⁻³), or high density (1200 – 1800 kg.m⁻³) biobased concretes. The fire behaviour of these materials is still poorly documented. In this work, combustion microcalorimetry tests were conducted to measure the amount of energy released during the combustion of various bioresources while bomb calorimeter tests allowed quantifying their gross heat of combustion. Cone calorimeter experiments were performed to study the ignition of biobased concretes. Results provide general knowledge and data regarding the fire behaviour of bioconcretes. It was observed that only the lightest ones ignite. It appears that ignition relies on two parameters: the combustion energy density of bioconcrete and the energy required to heat the material to the ignition temperature. One criterion is proposed to predict ignition. It accounts for different endothermic processes, such as the bioresource pyrolysis, the possible decomposition of the binder and the heating phenomenon itself up to the pyrolysis temperature
Fonctionnalisation par traitement au plasma froid de fibres de carbone recyclées pour une réincorporation dans des composites PA6/RCF
No full textInternational audienc
Amélioration de l’Élicitation d'Exigences grâce à la Fouille de Magasin d'Applications
No full textTraditional requirements elicitation methods typically involve interviews, observations, questionnaires, prototyping, etc. Despite their usefulness, these methods heavily depend on the knowledge of stakeholders and requirements engineers. In the fast-paced and highly competitive mobile app market, staying ahead of evolving trends is particularly challenging. App stores like Google Play and the Apple Store offer a vast repository of apps, providing an opportunity to identify similar products and gain valuable insights. However, the sheer volume of available apps makes manual analysis a daunting and time-consuming task. To bridge this gap, our research focuses on leveraging app store data to streamline and enhance the requirements elicitation process.In this thesis, we focus on three challenges of requirements elicitation: refinement of initial idea, rapid and accessible prototyping, and continuous requirements elicitation after the app's release. To tackle these challenges, we developed three innovative approaches that leverage app descriptions, introduction images, and app reviews from app stores. First, we proposed a method to identify relevant app descriptions and extract key features for sub-feature recommendation, which helps refine high-level ideas/features into detailed features. Second, by mining app introduction images from Google Play, we developed a GUI search engine that allows users to quickly find relevant screenshots based on textual queries, thereby accelerating the prototyping process. Third, we introduced an automated pipeline to extract requirements-related information from large volumes of app reviews. Empirical evaluations demonstrate the effectiveness of these three approaches. Additionally, we conducted a case study on the requirements elicitation process for a health monitoring app designed for seniors, which further validated their effectiveness in a real-world scenario.Les méthodes traditionnelles de collecte des exigences impliquent généralement des interviews, des observations, des questionnaires, la création de prototypes, etc. Malgré leur utilité, ces méthodes dépendent fortement des connaissances des parties prenantes et des ingénieurs en charge de l'élaboration des exigences. Dans le marché des applications mobiles, en constante évolution et hautement concurrentiel, rester à la pointe des tendances est particulièrement difficile. Les magasins d'applications comme Google Play et Apple Store offrent un vaste répertoire d'applications, ce qui constitue une opportunité d'identifier des produits similaires et d'obtenir des informations précieuses. Cependant, le volume considérable d'applications disponibles rend l'analyse manuelle ardue et chronophage. Pour combler cette lacune, nos recherches se concentrent sur l'exploitation des données des magasins d'applications pour rationaliser et améliorer le processus de collecte des exigences.Dans cette thèse, nous nous concentrons sur trois défis liés à la collecte des exigences : le raffinement de l'objectif initial de l'application, la création rapide et accessible de prototypes d'interfaces graphiques, et la collecte continue des exigences après la mise sur le magasin d'applications. Pour relever ces défis, nous avons développé trois approches innovantes qui tirent parti de trois sources d'information provenant des magasins d'applications: les descriptions d'applications, les images d'introduction et les avis d'utilisateurs. Nous proposons d'une part une méthode pour identifier les descriptions d'applications pertinentes et extraire les fonctionnalités clés en vue de recommandations de sous-fonctionnalités, ce qui aide à affiner les fonctionnalités générales. D'autre part, en exploitant les images d'introduction des applications sur Google Play, nous avons développé un moteur de recherche d'interfaces graphiques qui permet de trouver rapidement des captures d'écran pertinentes en fonction de requêtes textuelles, accélérant ainsi le processus de prototypage. Enfin, nous introduisons une chaîne automatisée pour extraire les informations liées aux exigences à partir d'un grand volume d'avis d'utilisateurs. Des évaluations empiriques démontrent l'efficacité de ces trois approches. Nous mettons en pratique nos travaux sur un cas d'étude relatif à la collecte des exigences pour une application de suivi de l'activité physique de personnes âgées
Constant low-to-moderate mechanical asymmetries during 800-m track running
No full textInternational audienceIntroduction Modifications in asymmetry in response to self-paced efforts have not been thoroughly documented, particularly regarding horizontally-derived ground reaction force variables. We determined the magnitude and range of gait asymmetries during 800 m track running. Methods Eighteen physical education students completed an 800 m self-paced run on a 200 m indoor track. During the run, vertical and horizontal ground reaction forces were measured at a sampling frequency of 500 Hz using a 5 m-long force platform system, with data collected once per lap. The following mechanical variables were determined for two consecutive steps: contact time and duration of braking/push-off phases along with vertical/braking/push-off peak forces and impulses. The group mean asymmetry scores were evaluated using the “symmetry angle” (SA) formula, where scores of 0% and 100% correspond to perfect symmetry and perfect asymmetry, respectively. Results There was no influence of distance interval on SA scores for any of the nine biomechanical variables ( P ≥ 0.095). The SA scores were ∼1%–2% for contact time (1.3 ± 0.5%), peak vertical forces (1.8 ± 0.9%), and vertical impulse (1.7 ± 1.0%). The SA scores were ∼3%–8% for duration of braking (3.6 ± 1.1%) and push-off (3.2 ± 1.4%) phases, peak braking (5.0 ± 2.1%) and push-off (6.9 ± 3.1%) forces as well as braking (7.6 ± 2.3%) and push-off (7.7 ± 3.3%) impulses. The running velocity progressively decreased at 300 m and 500 m compared to that at 100 m but levelled off at 700 m ( P < 0.001). Discussion There were no modifications in gait asymmetries, as measured at 200-m distance intervals during 800-m track running in physical education students. The 800 m self-paced run did not impose greater mechanical constraints on one side of the body. Experimental procedures for characterizing the gait pattern during 800 m track running could be simplified by collecting leg mechanical data from only one side
Jumeaux Numériques d’Hydrosystèmes pour la Gestion des Crues : Ombre numérique ou véritable jumeau numérique ?
No full textNational audienc
Multilabel Classification in IoT NIDS: A Proposed Cross Machine Learning Pipeline
No full textInternational audienceNetwork Intrusion Detection Systems (NIDS) are among the most dynamic cybersecurity assets in most organizations' cyber infrastructure because they provide a reliable means of protection against cyberattacks. In recent years, the expansion of Industry 5.0 technologies has resulted in more IoT devices being connected to the Internet, increasing attack surfaces and placing additional burden on NIDS. In the research world, ML-based solutions for IoT NIDS are evolving very quickly. However, the availability of high-quality publicly available datasets in this area diminishes the potential of this niche. This work compares three IoT-based datasets (ToN-IoT, X-IIoTID and UNSWNB15) through in-depth analysis of their features and architecture. The goal is to assess their readiness for a proposed cross-machine learning pipeline for the purpose of generalizability of the multi-label classification ML model. Using key ML performance metrics such as F1 score, precision, and recall, our results show that our model performed reasonably well in identifying different attack scenarios on each dataset
Purpose in Life and Risk of Falls: A Meta-Analysis of Cross-Sectional and Prospective Associations
No full textInternational audienceBackground and Aim: Purpose in life is an aspect of well-being that is associated with better health outcomes in older adulthood. We examine the association between purpose in life and likelihood of a recent fall and risk of an incident fall over time. Methods: Purpose in life and falls were reported concurrently and falls were reported again up to 16 years later in four established longitudinal studies of older adults (total N = 25,418). Results: A random-effects meta-analysis of the four samples indicated that purpose was associated with a 14% lower likelihood of having fallen recently at baseline (meta-analytic OR = 0.88, 95% CI [0.84–0.92]). Among participants who reported no falls at baseline ( N = 15,632), purpose was associated with a nearly 10% lower risk of an incident fall over the up to 16-year follow-up (meta-analytic HR = 0.92, 95% CI [0.90–0.94]). These associations were independent of age, sex, race, ethnicity, and education, were not moderated by these factors, and persisted controlling for physical activity and disease burden. Conclusion and Recommendations: Purpose in life is a meaningful aspect of well-being that may be useful to identify individuals at risk for falling, particularly among individuals without traditional risk factors, and be a target of intervention to reduce fall risk
Quelle plus-value de l’hypoxie lors de l’entrainement en répétition de sprints chez le sportif : entre effet placebo et réponse physiologique ?
No full textRepeated sprint in hypoxia (RSH) is a training method introduced in 2013, which is said to quickly improve physical performance, such as the ability to repeat sprints, even in elite athletes. However, some aspects still need to be explored to optimize its effectiveness, such as the ideal altitude, the recovery time before competition, and the influence of the placebo effect. To investigate these points, we conducted three studies.First, we aimed to determine whether the level of blood desaturation during RSH training was associated with physical performance during post-intervention tests. The results did not show any difference in performance enhancement based on the participants' desaturation levels. We hypothesized (i) that various methodological biases (placebo effect, Pygmalion effect) present in some studies might overestimate the added value of RSH and/or (ii) that the recovery period before the post-tests was too short to observe overreaching effects.As a result, we conducted a second study in which three groups performed a sprint repetition protocol: one in control conditions, another believing they were in hypoxia, and the third actually in hypoxia. After this protocol, participants completed two post-test sessions. The results did not allow us to conclude any added value from either hypoxia or the placebo effect. We then hypothesized that our exercise modality (effort/recovery time ratio) was not optimal to achieve the expected benefits of RSH.Thus, we conducted a final study in which participants performed sprint repetition sessions with different ratios. The results concerning the activity of the autonomic nervous system did not indicate any differences between the ratios studied.In conclusion, although promising, RSH training still requires further research to define optimal parameters and clarify the underlying mechanisms. This thesis highlights the importance of methodological rigor in the design of RSH studies to ensure a more reliable interpretation of the results. Such an approach will lead to a better understanding of the true benefits of RSH and help optimize its effectiveness for athletes.La répétition de sprints en hypoxie (RSH) est une méthode d’entrainement introduite en 2013, qui permettrait d’améliorer rapidement les performances physiques telles que la capacité à répéter les sprints, et ce, même chez des sportifs élites. Cependant, certains aspects restent à explorer pour en optimiser l'efficacité, comme l'altitude idéale, le délai de récupération avant la compétition ou l'influence de l'effet placebo. Afin d’explorer ces différents points, nous avons mis en place trois études.Dans un premier temps, nous avons cherché à déterminer si le niveau de désoxygénation sanguine pendant un entrainement RSH était associé aux performances physiques lors des tests après intervention. Les résultats n'ont pas montré de différence de progression en fonction de la désoxygénation des participants. Nous avons ainsi supposé (i) que les différents biais méthodologiques (effet placebo, effet Pygmalion) présents dans certaines études pouvaient surestimer la plus-value du RSH et/ou (ii) que la période de récupération avant les post-tests était trop courte pour observer des effets de surcompensation.Par conséquent, nous avons mis en place une deuxième étude dans laquelle trois groupes ont effectué un protocole de répétition de sprints : l’un en condition normoxie, l’autre pensant être en hypoxie (normoxie), et le dernier étant réellement en hypoxie. Après ce protocole, les participants ont effectué deux sessions de post-tests. Les résultats ne permettent pas de conclure à l’existence d’une plus-value ni de l’hypoxie ni de l’effet placebo pour l’amélioration des performances physiques. Nous avons donc émis l’hypothèse que notre modalité d’exercice (ratio temps d’effort : récupération) n’était pas optimale pour obtenir les gains escomptés du RSH.Ainsi, nous avons réalisé une dernière étude dans laquelle les participants ont effectué des séances de répétition de sprints avec différents ratios. Les résultats obtenus ne montrent pas de différences entre les impacts sur l’activité du système nerveux autonome, peu importe le ratio temps d’effort : récupération utilisée.En conclusion, bien que prometteur, l'entrainement en RSH nécessite encore des recherches approfondies pour en définir les paramètres optimaux et en clarifier les mécanismes sous-jacents. Cette thèse met en lumière l'importance d'une rigueur méthodologique dans la conception des études sur le RSH afin de garantir une interprétation plus fiable des résultats. Une telle démarche permettra de mieux comprendre les véritables bénéfices du RSH et d'en optimiser l'efficacité pour les athlètes
An intra-yarn capillary pressure and permeability assessment with a new suitable device
No full textDOI Proceedings : 10.60691/yj56-np80International audienceThe present work sets a methodology to extend the applicability of permeability and capillary pressure characterisation at the yarn scale more than the usual fabric scale. It is required for simulation of manufacturing by Liquid Composite Moulding (LCM) processes of 3D reinforcements such as interlocks. A proof of concept demonstrating the extendibility of the theories developed for fabrics is shown and an application in numerical simulation will be shown in further works
Aerosolomics based approach to discover source molecular markers: A case study for discriminating residential wood heating vs garden green waste burning emission sources
No full textInternational audienceBiomass burning is a significant source of particulate matter (PM) in ambient air and its accurate source apportionment is a major concern for air quality. The discrimination between residential wood heating (RWH) and garden green waste burning (GWB) particulate matter (PM) is rarely achieved. The objective of this work was to evaluate the potential of non-targeted screening (NTS) analyses using HRMS (high resolution mass spectrometry) data to reveal discriminating potential molecular markers of both sources. Two residential wood combustion appliances (wood log stove and fireplace) were tested under different output conditions and wood moisture content. GWB experiments were carried out using two burning materials (fallen leaves and hedge trimming). PM samples were characterized using NTS approaches with both LC- and GC-HRMS (liquid and gas chromatography-HRMS). The analytical procedures were optimized to detect as many species as possible. Chemical fingerprints obtained were compared combining several multivariate statistical analyses (PCA, HCAand PLS-DA). Results showed a strong impact of the fuel nature and the combustion quality on the chemical fingerprints. 31 and 4 possible markers were discovered as characteristic of GWB and RWH, respectively. Complementary work was attempted to identify potential molecular formulas of the different potential marker candidates. The combination of HRMS NTS chemical characterization with multivariate statistical analyses shows promise for uncovering organic aerosol fingerprinting and discovering potential PM source markers