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Heat transfer modelling of radiant flux from a halogen lamp for enhancing Infrared thermography simulation
No full textInternational audienceInfraRed Thermography (IRT) is widely used in Non-Destructive Evaluation (NDE) for its ability to provide real-time, two-dimensional, non-contact measurements of heat distribution. Enhancing the analysis of thermal results requires a comprehensive understanding of the entire measurement chain from the heat source, through propagation, to detection, signal processing and data interpretation, which demands an effective combination of simulation and experimental approaches. This study presents the modelling of heat transfer, with particular emphasis on accurately characterising the radiant heat flux emitted by a halogen lamp. A fluxmeter sensor was employed to measure the radiant heat flux at different distances and spatial locations. Subsequently, 3D heat transfer models incorporating these heat sources were established and applied to an Acrylonitrile Butadiene Styrene plate to investigate thermal behaviour and the influence of factors within the measurement chain. Critical parameters were also considered, including thermal conductivity, convective heat transfer coefficients, fluxmeter sensor sensitivity, heat flux characteristics and measurement methods. Simulation results were validated against experimental data using both an infrared camera and a pyrometer and demonstrated strong agreement. Relative errors were below 4.2 % for pyrometer measurements, whereas slightly higher errors, up to 5.9 % for IRT method, which is mainly attributed the influence of environmental factors on this technique. These findings confirm the accuracy and reliability of the calibrated heat source and modelling parameters. Integrating experimental data into the thermal simulation enhances both accuracy and consistency, thereby establishing a more robust framework for the application of numerical methods throughout the IRT measurement chain in NDE applications
Compact segmented meta-liners for enhanced acoustic absorption with grazing flow
No full textInternational audienc
Comparative study of three cellular materials under blast and sustained shock wave
No full textInternational audienceThis study investigates the mechanical response of three cellular materials—polyisocyanurate (PIR), autoclaved aerated concrete (AAC), and Aluminum Lightweight Foam (ALF, Nufoam® 140)—under blast and shock loading conditions. The research aims to provide experimental data for optimizing building protection against explosion hazards. Laboratory-scale tests were conducted using a shock tube to generate blast and sustained shock waves. The materials’ responses were analyzed using high-speed imaging and digital image correlation. Results indicate that PIR exhibits significant deformation under sustained shocks but shows recovery under blast loading. AAC demonstrates erosion-based energy dissipation, with material loss concentrated at the extremities. ALF, serving as a reference, shows excellent mechanical energy dissipation. The study highlights the potential of these materials for applications requiring both thermal insulation and blast resistance, contributing to the development of predictive tools and larger-scale experiment designs
Microwave pretreatment and fermentation conditions affect acidogenic fermentation of wheat straw and horse manure
No full textInternational audienceThis study aimed to investigate the influence of microwave pretreatment and fermentation parameters on acidogenic fermentation of wheat straw and horse manure. Four different inoculation strategies were tested on wheat straw fermentation, including horse dung, cow dung, aerobic sludge, and wheat straw indigenous inoculum at two different pH (6 and 10). The best yield was achieved with horse dung, reaching 0.172 ± 0.005 gCOD/gVS after seven days at pH 6. However, for horse manure fermentation, lignocellulosic substrate suitable for fermentation without external inoculation, a pretreatment was needed to deactivate methanogenic archaea and solubilize sugars. Microwave parameters such as power (200 or 1000 W), liquid/solid (L/S) ratio (6 or 17) and energy (7 Wh/gVS or 12 Wh/gVS) were assessed on substrate solubilization and metabolic yield. The best pretreatment condition, at 200 W for 15 min with a L/S ratio of 17, led to a metabolic yield of 0.134 ± 0.029 g COD/gVS after seven days. This condition suppressed methanogenic activity while increasing soluble sugars and Chemical Oxygen Demand (COD) by 44 % and 58 %, respectively. Finally, increasing volatile solid (VS) concentration during batch fermentation from 14 to 28 gVS/L of horse manure led to a significant metabolic profile change. Butyrate production was quadrupled for the 200 W pretreatment while total metabolite yield was unchanged. Overall, this study demonstrates that microwave pretreatment is an effective strategy to inhibit methanogenesis and enhance substrate solubilization, without significantly promoting volatile fatty acid production. In addition, modifying VS concentration can induce a notable metabolic shift
Opportunities from energy-loss near-edge fine structure analysis to track chemical and structural damage in zircon
No full textInternational audienceZircon (ZrSiO4) is the oldest-known mineral of Earth and an ubiquitous silicate in geochronology. More specifically, the accumulation of alpha decay damage in zircon over time significantly affects its physical and chemical properties, and can lead to a disturbance of the ages measured in this mineral. Therefore, analytical tools that enable comprehensive structural and chemical information at the nanoscale in this compound are highly sought after. In this context, we explore the electron energy-loss fine structures resulting from the excitation of O1s and Si2p core electrons in zircon, which are interpreted from ab initio calculations in a single-particle framework. An excellent agreement is obtained between the experimental and calculated fine structures, emphasizing the large distortion of the final electronic states induced by the core-hole potential. The O-K edge is particularly rich in information, with intense peaks dominated by O2p - Zr4d and O2p - Si3sp hybrids. This work suggests that the near-edge structures from the O1s and Si2p excitations accessible from electron energy-loss spectroscopy or X-ray absorption spectroscopy could be used as tools to follow, interpret and understand structural and chemical modifications in zircon subject to natural radiation damage. We illustrate the potential of this approach through the evolution of near-edge fine structures in a zircon sample that exhibits a locally amorphized zone formed by ultrafast laser excitation
On design, analysis, and hybrid manufacturing of microstructured blade-like geometries
No full textInternational audienceWith the evolution of new manufacturing technologies such as multi-material 3D printing, one can think of new type of objects that consist of considerably less, yet heterogeneous, material, consequently being porous, lighter and cheaper, while having the very same functionality as the original object when manufactured from one single solid material. We aim at questioning five decades of traditional paradigms in geometric CAD and focus at new generation of CAD objects that are not solid, but contain heterogeneous free-form internal microstructures. We propose a unified manufacturing pipeline that involves all stages, namely design, optimization, manufacturing, and inspection of microstructured free-form geometries. We demonstrate our pipeline on an industrial test case of a blisk blade that sustains the desired pressure limits, yet requires significantly less material when compared to the solid counterpart
New insights into Bismuth(III) based co-crystal with potential antibacterial activity against clinically relevant pathogens: Hydrothermal synthesis and comprehensive physico-chemical characterization
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Evaluating DayCent and STICS in simulating the long-term impact of contrasting organic resource amendments on soil organic carbon and maize yields in sub-Saharan Africa
No full textSource Agritrop Cirad (https://agritrop.cirad.fr/615006/)International audienceProblem: Low crop yields in sub-Saharan Africa mainly result from low soil fertility and insufficient nutrient inputs. A key component of Integrated Soil Fertility Management (ISFM), namely combining inputs of mineral fertilizers and organic resources, presents an opportunity to boost yields and maintain soil organic carbon (SOC) stocks in the long run. Soil-crop models help to assess the performance of ISFM under contrasting soil, climate, and management combinations. Yet, to date, most soil-crop models have been calibrated and tested in temperate conditions. Objective: Our objective was to evaluate and compare the performance of two different soil-crop models, DayCent and STICS, to represent crop yields and SOC dynamics under contrasting organic resource amendments. Methods: We used a large dataset representing 3384 cropping situations (site x season x treatment) from four long-term experiments in Kenya. Each experiment included the same treatments with the addition of two quantities of low- to high-quality organic resource amendments (high vs low C/N ratio, respectively), with (+N) and without (-N) mineral nitrogen fertilizer. Each treatment included a cropped and uncropped subplot, allowing for a unique stepwise calibration of soil and crop parameters. Results: Both models represented SOC and yield dynamics with similar accuracy across sites and treatments. They reproduced SOC dynamics well (nRMSE below 30 %) in the two clayey soils sites but not in the two sandy soils. Yet, in most sites they reproduced well SOC differences between high (Farmyard manure, Thithonia and Calliandra) and low-quality (maize stover and sawdust) organic resources. Models reproduced the average yield across sites and treatments similarly. They reproduced the positive effects of high-quality organic resources and the addition of mineral N on maize yield well. Models had similar inaccuracy in reproducing yield and yield variability under poor-quality organic resources and -N treatments. Conclusion: The stepwise calibration approach used in this study enabled highlighting the models' strengths and weaknesses in soil and plant simulations. The results suggest that the two models have similar strengths and struggle with the same problems despite having different structures. Collecting detailed plant (leaf area index, plant N uptake) and soil (water, nitrogen dynamics) in-season data from long-term experiments will be critical to exploit the full model complexity and improve their accuracy for tropical conditions
Itinéraire atypique d’une infirmière devenue patiente-experte addictions et infirmière en pratique avancée
No full textInternational audienceA nurse who worked for twenty years in a public hospital was led by her journey of recovery from addictive behaviors to specialize in this field. With a university degree in addiction studies and a patient-expert certification in addiction, she works in a non-profit addiction treatment center that values experiential knowledge. This unusual career path led her to develop a tool for overcoming addiction in the form of a book, the effects of which she measured on people receiving addiction treatment as part of her research for a master’s degree in advanced nursing practice. Testimonial.Une infirmière ayant exercé durant vingt ans à l’hôpital public a été amenée par son parcours de rétablissement de ses conduites addictives à se spécialiser dans ce domaine. Forte d’un diplôme universitaire d’addictologie et d’une certification patiente-experte addictions, elle travaille dans un centre d’addictologie associatif qui valorise les savoirs expérientiels. Ce cheminement atypique l’a conduite à proposer un outil pour se libérer de l’addiction sous la forme d’un ouvrage dont elle s’est appliquée à mesurer les effets sur des personnes accompagnées en addictologie dans le cadre d’une recherche pour l’obtention du master infirmier en pratique avancée. Témoignage