Portail des publications scientifiques IMT Mines Alès
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Ce que les comportements sur le terrain nous disent des chercheurs : une expérimentation réflexive menée en Cévennes
No full textInternational audienceLa crise écologique bouscule les savoirs scientifiques établis, elle requiert à ce titre une plusgrande réflexivité de la part des chercheurs pour ce qui est de leur rapport distancié au terrain.La question se pose de savoir comment favoriser une interconnexion qui leur permettrait de serendre attentif aux singularités des territoires. Souhaitant contribuer à ce mouvement, nousavons organisé une « sortie de terrain » avec des hydrologues pour analyser leur posture et leurspratiques. Nos résultats montrent que, s’il existe plusieurs rapports au terrain, ceux-ci ne sontjamais tout à fait dénués d’engagement sensible, corporel et esthétique, quand bien même cesengagements sont habituellement tus. Nous questionnons les postures épistémiques deschercheurs embarqués dans notre expérimentation et discutons des possibilités nouvelles quis’offrent pour le dialogue interdisciplinaire.The ecological crisis is shaking up established scientific knowledge, and as such requires greaterreflexivity on the part of researchers in terms of their distanced relationship with the field. Thequestion is how to encourage an interconnection that will enable us to be attentive to thesingularities of the territories. With a view to contributing to this movement, we organised a'field trip' with hydrologists to analyse their attitudes and practices. Our results show that, whilethere are many different relationships to the field, these are never entirely devoid of sensitive,physical and aesthetic engagement, even if these commitments are usually kept quiet. Wequestion the epistemic cultures of the researchers involved in our experiment and discuss thenew possibilities for interdisciplinary dialogu
Societal issues from the mining legacy in the Cévennes: Questioning the habitability of post-mining territories
No full textInternational audienc
Correlations to estimate the ground loading from small scale propane BLEVE experiments
No full textInternational audienceThis paper presents small-scale propane BLEVE (Boiling Liquid Expanding Vapor Explosion) experiments coupled with an investigation into ground loading dynamics. The experiments utilized cylindrical aluminum pressure vessels, with a diameter of 50 mm and a length of 300 mm. The controlled variables included burst pressure, liquid fill level, and weakened length. Both high and low-speed measurements of internal pressure and ground force were conducted during the experiments. The dependent variables analyzed were peak total ground load, force duration, and impulse. The findings from the study show trends in ground force and impulse with alterations in failure pressure, fill level and weakened length. Specifically, ground force and impulse exhibit an upward trend with increasing failure pressure, fill level and weakened length (cut length). For the first time, comprehensive correlations have been developed, incorporating the controlled variables, as well as theoretical boiling wave speed and vapor speed, to estimate the dependent variables, which represents a significant contribution in the field. However, the study does acknowledge the presence of scatter in the data, which are believed to be associated with the intricacies of the vessel opening process. It should be noted that this correlation has not been validated for larger scales. Once validated on a larger scale, these correlations can be directly applied in the design and practice of civil infrastructure to enhance the structural integrity. Additionally, the research has direct implications for industrial applications, allowing for the quantitative assessment of risks associated with bridge collapse during the transportation of PLGs
Utilizing Fine Marine Sediment as a Partial Substitute for Sand in Self-Compacting Concrete Specially Designed for Application in Marine Environments
No full textInternational audienceThe disposal of marine sediments poses a significant economic and environmental challenge on a global scale. To address this issue and promote resource optimization within a circular-economy paradigm, this research investigates the viability of incorporating untreated fine marine sediments as a partial replacement for sand in self-compacting concrete (SCC) designed especially for application in marine environments (an exposure class of XS2 and a resistance class of C30/37 according to standard NF EN 206). The concretes mis-design incorporating 30% by weight of sediment as a sand substitute was initially designed with the modified Dreux–Gorisse method. The findings indicate that it is feasible to design an SCC suitable for marine environments, incorporating 30% sediment replacement content and without significantly compromising concrete properties, durability, or the estimated lifespan of the formulated concretes. The integration of marine sediment as a sand substitute into the SCC mix design reduces the amount of binder and limestone filler without compromising the paste volume. This results in a significant saving of natural sand resources and a reduction in CO2 emissions for SCC made with marine sediment
Tannins as Biobased Molecules for Surface Treatments of Flax Wrapped Rovings for Epoxy/Flax Fabrics Biocomposites: Influence on Mechanical Properties through a Multi-Scale Approach
No full textInternational audienceThe present study examined the effect of biobased molecules grafted onto wrapped flax rovings on the mechanical properties of fabrics designed for epoxy-based biocomposites, aiming to optimize fiber/matrix adhesion. Biobased solutions, such as tannins from quebracho, were used to treat wrapped flax rovings in comparison to a non-biobased aminosilane solution used as a reference. The chemical treatment is performed using an innovative lab-scale impregnation line. The influence of the solution concentration has been investigated. SEM-EDX and FT-IR confirmed the grafting efficiency of molecules on wrapped rovings. Plain and 5-harness satin fabrics were then manufactured at lab scale with the resulting functionalized rovings. Tensile tests were carried out on rovings and on fabrics. A concentration of 1% silane is sufficient to improve the mechanical properties of rovings and fabrics. The addition of NaOH to tannins strengthens flax fiber rovings more than tannins alone, and the weave pattern influences mechanical performance
Experimental assessment and artificial neural network modeling of dynamic and steady-state methane biofiltration in the presence of volatile organic compounds
No full textInternational audienceThis study examined the artificial neural network (ANN) modeling of simultaneous biofiltration of methane (CH4) with two volatile organic compounds (VOCs): xylene and ethylbenzene, using an inorganic packed bed biofilter at an empty bed residence time (EBRT) of 4.5 min. Results showed that the removal efficiency (RE) of CH4 was in the range of 50 to 60% for concentrations of 1000 to 10,000 ppmv (0.6 to 6.5 g m−3), while the VOCs-REs were between 70 and 90% for X and EB concentrations in the range of 200 to 500 ppmv (0.9 to 2.2 g m−3). Artificial neural networks were used to predict and simulate the performances of the biofilter, based on a database containing previous biofiltration works. The ANN1 (architecture of 3 (input layer)-18 (hidden layer)-1 (output layer)) accurately predicted CH4 conversion at the pseudo-steadystate condition, while the ANN2 (4 (input layer)-18 (hidden layer)-2 (output layer)) predicted the simultaneous conversion of CH4 and VOCs with slightly lower accuracy than ANN1. The ANN3 (4 (input layer)-30 (hidden layer)-1 (output layer)) successfully predicted the acclimation period and final phase (CH4 concentration of 10,000 ppmv) of the biofilter but could not accurately predict the transient phases and showed differences (up to 20%) from experimental results once the CH4 concentration was changed. This study developed a decision support and prediction tool to anticipate the performance of biofilters in treating residual gases containing CH4 and VOCs, avoiding costs and delays associated with experimentation
Control of halloysite nanotubes localization into a LLDPE/EVA (70/30) blend through specific chemical modifications and sequence of mixing during extrusion
No full textInternational audienceThe control of the localization of halloysite nanotubes (HNT) in a linear low-density polyethylene/ethylene-vinyl acetate copolymer (LLDPE/EVA, 70/30) blend was studied through three approaches: i) Functionalization of the filler, ii) Addition of a compatibilizer and iii) Modification of the processing sequence. First, the HNT surface modification was carried out with three different organosilanes (3-aminopropyltriethoxysilane (APTES), dodecyltricholosilane (DTCS) and triacontyltrichlorosilane (C30)). Grafting amounts about 0.10 mmol/g were reached whatever the nature of the organosilane. Then, the unmodified and modified HNT were mixed with a LLDPE/EVA (70/30) polymer blend using a microextruder and the localization of the fillers were scrutinized by scanning electron microscopy (SEM) analysis. It was observed that both the neat HNT and modified HNT were mostly localized in the EVA phase. These observations were also discussed according to the wettability coefficient determined for neat HNT and modified HNT thanks to contact angle measurements. The addition of PE-g-MA as a compatibilizer to the blend containing the HNT-APTES allowed to localize the HNT in the LLDPE phase. Finally, the influence of the mixing sequence of the different components was evaluated by using a twin-screw extruder, and it was successfully used to localize the modified HNT into the LLDPE phase
Motion2Language, Unsupervised Learning of Synchronized Semantic Motion Segmentation
No full textLe preprint de cet article est consultable : 10.48550/arXiv.2310.10594.International audienceIn this paper, we investigate building a sequence to sequence architecture for motion-to-language translation and synchronization. The aim is to translate motion capture inputs into English natural-language descriptions, such that the descriptions are generated synchronously with the actions performed, enabling semantic segmentation as a byproduct, but without requiring synchronized training data. We propose a new recurrent formulation of local attention that is suited for synchronous/live text generation, as well as an improved motion encoder architecture better suited to smaller data and for synchronous generation. We evaluate both contributions in individual experiments, using the standard BLEU4 metric, as well as a simple semantic equivalence measure, on the KIT motion-language dataset. In a follow-up experiment, we assess the quality of the synchronization of generated text in our proposed approaches through multiple evaluation metrics. We find that both contributions to the attention mechanism and the encoder architecture additively improve the quality of generated text (BLEU and semantic equivalence), but also of synchronization
Model‐based architecting evaluation method for the delivery of complex nuclear projects
No full textInternational audienceFacing the organizational and technological complexity of nuclear infrastructures (NI), the public reluctance in nuclear technology and the increasing restrictive regulatory environment, improving the conceptualization and evaluation of NI architecture is crucial for the successful completion of NI projects. Indeed, many technical engineering difficulties or delays in delivery can be avoided by deepening the design and evaluation of NI architectures. In a context where model-based systems engineering (MBSE) is becoming more and more relevant, it is interesting to integrate evaluation into this process. Although the architecture evaluation (AE) process is rather well defined in the literature and linked to system analysis practices, it is quite difficult to deploy and pilot within complex NI projects. This article proposes a model-based method, EVAluation for Critical Infrastructure Model Based System Engineering (EVA-CIME), to facilitate the deployment of AE processes on a project. The components of this method are described and illustrated in a study of a NI design. The benefits and limitations of EVA-CIME in its state of development are discussed and lead to the conclusion that the method should be extended to foster an AE culture within the company itself
Beyond Arm Capacity in Chronic Stroke: Evaluating Paretic Arm Non-Use Through Arm Efficiency—A Cross-Sectional Study
No full textInternational audienceBackground. After a stroke, the use of the paretic arm is determined by its capacity (what it can or cannot do). When both arms have capacity to perform a task, the choice of which arm to use must be based on another criterion, probably by comparing the efficiency of each arm. Two numerical models account for this: the capacity model (the paretic arm is chosen in preference) and the efficiency model (the most efficient arm is chosen). Objective. To numerically determine whether capacity or efficiency best predict the use of the paretic arm in activities of daily living. Methods. We performed numerical simulations to predict paretic arm use with either the capacity model or the efficiency model. We used the Bayesian Information Criterion (BIC) to compare the adequacy of the 2 models in predicting clinical and accelerometric data collected from 30 patients with chronic stroke. Results. The efficiency model predicted arm use in activities of daily living better than the capacity model (BIC = -66.95 vs -5.89; root mean square error = 0.26 vs 0.72). Conclusions. The study highlights the importance of considering efficiency when assessing paretic arm non-use. Assessing individuals' arm efficiency should help personalize rehabilitation strategies after stroke.</div