Portail des publications scientifiques IMT Mines Alès
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Modélisation des Données de Maintenance des Bâtiments : Vers une Approche Sémantique
No full textInternational audienc
Landscape Drivers of Floods Genesis (Case Study: Mayo Mizao Peri-Urban Watershed in Far North Cameroon)
No full textInternational audienceLandscape has significant effects on hydrological processes in a watershed. In the Sudano-Sahelian area, watersheds are subjected to a quick change in landscape patterns due to the human footprint, and the exact role of the actual landscape features in the modification of the hydrological process remains elusive. This study tends to assess the effects of landscape on the genesis of the runoff in the Mayo Mizao watershed. To achieve this goal, 62 infiltration tests were performed at different points and depths (5 cm and 20 cm) using the double-ring method and the Porchet method. The results show that the combination of many factors (soil type, land use, and farming practices) can guide the hydraulic conductivity behavior of soils. For example, at 5 cm depths, clayey-evolved soils, such as vertisols and halomorphic soils, inhibit infiltration, as opposed to non-evolved mineral soils, such as lithosols and clayey-sandy soils. However, at 20 cm depths, gray soils with halomorphic tendencies followed by vertisols have a low sensitivity to infiltration, as opposed to soils derived from loose materials and halomorphic soils. For a given soil type, rainfed crops are the primary land use that runs against infiltration. However, the effect of tillage varies according to the soil type. Finally, given the extent of vertisols and halomorphic soils in the Far North region of Cameroon in general, and in the Mayo Mizao watershed in particular, and regarding the increase in cultivated areas, a probable reduction in the infiltration capacity of soils in this region is to be expected in the medium term. The results of this study can be used as a basis for land-use planning and sustainable watershed management in semi-arid tropical zones
Durable and highly hydrophobic flax fabrics designing via “grafting to” method using catalysed hydrosilylation
No full textInternational audienceHighly hydrophobic flax fabrics with durable properties were prepared via “grafting to” method for self-cleaning application. Flax fabrics were firstly functionalized with vinyl groups using 1,3-divinyltetramethyldisilazane (DVTS). Then, the vinyl functionalized flax fabrics were grafted by poly(hydromethylsiloxane-co-dimethylsiloxane) (PDMS-co-PHMS) via a hydrosilylation reaction using Karstedt catalyst, between Si-H groups present in PDMS-co-PHMS and vinyl groups present onto the vinyl functionalized flax fabrics. The prepared fabrics were characterized using Fourier-transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), X-rays fluorescence, confocal laser scanning microscopy (CLSM) and tensile test. The modified fabrics displayed highly hydrophobic properties with contact angle (θ) about 147° ± 5 and a sliding angle (SA) of about 15° ± 2, making them ideal for practical self-cleaning applications. Furthermore, good durability with excellent washing resistance was also obtained for these fabrics
Multiscale analysis of hierarchical flax-epoxy biocomposites with nanostructured interphase by xyloglucan and cellulose nanocrystals
No full textInternational audienceNatural biological systems feature hierarchical nanostructured architectures achieving high strength and toughness. In this work, the spontaneous adsorption of xyloglucan (XG) and cellulose nanocrystals (CNC) onto flax fabrics is considered to develop hierarchical interphases with improved interfacial adhesion in epoxy-based biocomposites. A multi-scale analysis is carried out, from the nano & micrometric scale with the characterization of fibre surface topography, work of adhesion and interfacial shear strength (IFSS) between flax fibres and epoxy resin, to the macroscopic scale with the transverse mechanical properties of biocomposites. At the fibre scale, XG and CNC increase the surface roughness of flax fibres, as well as their adhesion to epoxy resin with IFSS improved by 60 %, up to 22.3 MPa. At the composite scale, the treatments have a major influence on the cohesion of flax cell walls and microstructure of the biocomposites. Transverse tensile tests reveal both cohesive and adhesive interfacial failure
A new method based on TGA/FTIR coupling to quantify the different thermal degradation steps of EVA/HNT composites prepared by different processing
No full textPre-print accessible : https://papers.ssrn.com/sol3/papers.cfm?abstract_id=4557212International audienceThe aim of the present article is to expose a new method based on TGA-FTIR coupling to quantify the different steps of the thermal degradation of EVA in the presence of HNT. Moreover, this quantification of the thermal degradation was also correlated to the color change. EVA/HNT composites were processed with different processing conditions: solvent casting in THF or melt blending at different temperatures. The HNT fillers content (from 10 wt% up to 30 wt%) and the melt blending temperature (at 130 °C, 150 °C, 170 °C and 190 °C) were varied. The thermal degradation of EVA in the presence of HNT presents three noticeable steps as evidenced by TG analysis: i) P1, which was identified as the catalytic degradation of vinyl acetate (VA) part of EVA occurring during the heating ramp (around 250 °C), ii) P2, which is the main degradation of VA (around 350 °C) and iii) P3, which is the degradation of the polyethylene chain of EVA (around 500 °C). Nevertheless, in the case of melt blended EVA/HNT composites, macroscopic changes (strong smell and browning color) indicate a thermal degradation occurring during the melt blending process, namely P0. FTIR-TGA coupling allows to quantify the contribution of P0, P1 and P2 (thermal degradation of VA units of EVA) using Gram Schmidt curves of released acetic acid gas which are obtained from the Cdouble bondOac. band of acetic acid at 1795 cm−1. The contribution of each thermal degradation step of the VA part of EVA (named P0 to P2) was then quantified and reported as A0 to A2, respectively. The blending process (solvent or melt) such as the HNT fillers content and the melt blending temperatures have a significant influence on the EVA thermal degradation catalyzed by HNT. For example, it was shown that the thermal degradation of VA units occurring during the processing of EVA+ 30HNT composite (named A0 and catalyzed by the HNT) was of 40% for melt blending process (at 170 °C), whereas it was close to 0% for solvent casting process. Moreover, the macroscopic changes were evaluated by color measurements and an interesting correlation could be made between A0 and ΔE* which is the total color deviation. When a significant catalytic effect, during the melt process was observed (A0 values higher than 5%), the total color deviation ΔE* was increased linearly with A0. Finally, in order to avoid the catalytic effect of HNT on the EVA thermal degradation, a functionalization strategy has been developed with an organosilane leading to the suppression of P1, the catalytic degradation of VA in TG analyses
An overview on human-centred technologies, measurements and optimisation in assembly systems
No full textInternational audienceThis paper offers an in-depth examination of the ergonomics of human-centred assembly systems in Industry 4.0, where manual tasks remain essential. The use of advanced technologies such as motion capture (MOCAP) and virtual reality (VR) is analysed as ways to enhance system efficiency and improve worker well-being. The paper highlights the importance of optimising assembly system performance while considering both economic and human factors. Metrics to assess ergonomic risk and productivity are discussed based on human-centred technologies, and existing operational research models are explored to analyse how human factors could be considered in optimising system performance. Additionally, the paper explores potential future directions and how they could play a role in Industry 4.0
Digital in-line holography to explore saliva aerosolization mechanisms in speech
No full textInternational audiencePhonation produces aerosols, and speech has proven to be a pernicious, invisible, yet potent viral transmission route among asymptomatic individuals in the COVID-19 pandemic. To develop comprehensive mitigation strategies and mechanisms to control transmission, it is crucial to measure both the amount of aerosols produced by a speaking individual and the associated atomization processes. However, these biological emissions are hard to characterize since they are intermittent, faint, range drastically in size between 1 and 1000 μm, and form and travel rapidly, with speeds of a few to tens of meters per second. Here, we present digital inline holography (DIH) as a lens-less and powerful tool to overcome many of these experimental challenges. Focusing on speech-induced aerosolization, we demonstrate the capacity of DIH to image the rapid formation, elongation, and deformation of saliva filaments in three dimensions and directly at the mouth of a speaking individual. The size of both the filaments and the subsequent aerosolized droplets are accessible over a field of view spanning several centimeters cubed. We quantify the droplets produced by distinct plosive consonants (/p/ and/t/) and we observe how filaments destabilize with a characteristic whipping dynamic, emitting rotational dumbells with liquid lobes linked by thinning saliva threads. We also image high-speed air fronts produced during plosion, with speeds as fast as tens of meters per second, classifying plosive consonant phonation as a violent atomization event like sneezing
Effect of Transcutaneous Auricular Vagus Nerve Stimulation in Chronic Low Back Pain: A Pilot Study
No full textInternational audienceBackground/Objectives: Chronic low back pain (CLBP) is a common condition with limited long-term treatment options. Vagus nerve stimulation (VNS) has shown potential for pain improvement, but its use in CLBP remains underexplored. Our aim was to evaluate the efficacy, feasibility and tolerability of transcutaneous auricular vagus nerve stimulation (taVNS) in reducing pain and improving functional outcomes in CLBP patients. Methods: Thirty adults with CLBP (VAS ≥ 40/100) participated in this open-label pilot study (NCT05639270). Patients were treated with a taVNS device on the left ear for 30 min daily over a period of 3 months. The primary outcome was a reduction in pain intensity (VAS) at 1 month. Secondary outcomes included pain intensity at 3 months, disability (Oswestry Disability Index, ODI), quality of life (EQ-5D-5L), catastrophizing and psychological distress. In addition, compliance and adverse events were monitored. Results: After 1 month, 27 patients were evaluated. VAS scores decreased significantly by 16.1 (SD = 17.9) mm (p < 0.001) and by 22.5 (25) mm (p < 0.001) after 3 months (24 patients were analyzed). Functional disability improved with an average reduction in ODI of 11.9 (11.1) points (p < 0.001) after 3 months. Other patient-reported outcomes also improved significantly over the 3-month period. Overall, 51.9% of the patients achieved clinically meaningful pain reduction (≥20 mm), and no serious adverse events were reported. Treatment adherence was good, with half of the patients achieving 80% adherence. Conclusions: This pilot study suggests that taVNS is a feasible, safe and potentially effective treatment for CLBP that warrants further investigation in a randomized controlled trial compared to sham stimulation