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Impact of the type of particle boards on the nitrogen fate during their pyrolysis and combustion
No full textInternational audienceParticle boards, wastes made out of wood particles bonded with nitrogen-rich adhesives, produce high NOx emissions during combustion, requiring control in biomass grate furnaces. However, the diversity of particle board feedstocks has often been overlooked, and the specific effects of different types have not been studied, despite accounting for over 10 % of the total volume.This work analyzes nitrogen behavior during combustion of standard, moisture-resistant, and fire-retardant particle boards. The combustion process was investigated as a whole, but also by proceeding separately to pyrolysis and char oxidation experiments. Thermogravimetric analysis and experiments conducted in a cross-fired fixed bed reactor were performed under both air and inert (N2) atmospheres. The nitrogen content in various combustion products (incondensable gases, condensates, and residual solids) was quantified to assess the impact of chemical treatments on nitrogen fate.Results showed that standard and moisture-resistant particle boards showed comparable combustion behaviors. Notable differences emerged during the combustion of fire-retardant particle boards, likely due to the influence of fire-retardant agents. In these cases, a slower heating rate within the bed and reduced hydrogen cyanide (HCN) emissions were observed compared to the other two types. Across all experiments, most of the nitrogen released was found in condensates
Image synthesis using a physics-informed diffusion model for crack detection with laser flying spot thermography
No full textInternational audienceIn non-destructive testing for metallic materials, ‘Flying-spot’ thermography is a method for detecting cracks based on the infrared scanning of samples by a local laser heat source. However, identifying a crack from other surface artefacts such as air ducts or non-planar shapes on the material surface can be challenging. That is why a recent series of works has proposed the use of deep learning techniques, which can exploit contextual information but require a significant amount of data. Some of these works use a diffusion model to increase the amount of data available to train the defect detection model. However, the diffusion model only imitates the training images it was fed and therefore, there is no physical meaning enforced to the images it generates. This can cause some synthetic images to exhibit temperature fields that do not comply with the diffusion law, or even contain obvious inconsistencies. In this paper, we propose the implementation of a physics-informed diffusion model to generate synthetic thermal images with a real physical meaning. In the literature, the integration of physical information is achieved using a partial differential equation (PDE). In contrast, we propose to directly incorporate the solution of the equation for a semi-infinite homogeneous solid (i.e. a defect-free material). To evaluate the benefits of such a model, several metrics are measured such as the Fréchet Inception Distance, the physical error and the speed of convergence, but also the performance on a downstream anomaly detection task
Étude de l'évaporation de monomère et de la formation de pores au cours de la polymérisation d'une résine acrylique réactive
No full textInternational audienceDue to the highly exothermic nature of free-radical polymerization and the low boiling point of methyl methacrylate (MMA), one of the key issues in reactive acrylic matrix composites manufacturing is to limit the formation of porosities. Understanding the evaporation behavior of these resins during the reaction is therefore crucial to predict void growth in these matrices. In this study, Elium® C195E resin was analyzed by TGA under various dynamic and isothermal conditions. In addition, an experimental set-up for direct observation of void growth during free-radical polymerization was developed. The obtained curves highlighted the strong coupling between polymerization and evaporation, as well as the volatility of MMA, with significant evaporation above 40 °C. Initial observations of heterogeneous nucleation and void growth in the resin during polymerization have shown very promising results. A further observation campaign with this set-up will allow to better control the various parameters governing this phenomenon.Du fait du caractère très exothermique de la polymérisation radicalaire et de la faible température d’ébullition du méthacrylate de méthyle (MMA), l’un des principaux enjeux de la fabrication de composites à matrice acrylique réactive réside dans la capacité à limiter la formation de porosités. La compréhension du comportement en évaporation de ces résines au cours de la réaction de polymérisation est donc cruciale pour prédire la croissance de pores dans ces matrices. Dans cette étude, la résine Elium® C195E est analysée par ATG sous différentes conditions dynamiques et isothermes. D’autre part, un dispositif expérimental d’observation directe de la croissance de pores au cours de la polymérisation radicalaire a été développé. Les courbes obtenues ont mis en évidence le couplage fort entre polymérisation et évaporation ainsi que la volatilité du MMA, avec une évaporation marquée dès 40 °C. Les premières acquisitions de nucléation hétérogène et de croissance de pores dans la résine au cours de la polymérisation ont donné des résultats très encourageants. Une campagne d’observation plus approfondie avec ce dispositif permettra par la suite de mieux contrôler les différents paramètres régissant ce phénomène
Application of the coupled eulerian-lagrangian method to the roller compaction modelling
No full textInternational audienceRoller compaction of powders involves large deformations and its simulation using finite element method is often difficult due to the large mesh distortions. To solve the boundary value problem of roller compaction of powders, the Arbitrary Lagrangian-Eulerian (ALE) formulation incorporated in Abaqus/Explicit, has been applied to the roller compaction of pharmaceutical powders in 2D and 3D configurations [1]. In this method, the Lagrangian part is filled by the deformable material leading to excessive element distortions. An adaptive remeshing operation, needed to keep the quality of the mesh, increases the computation time. To overcome this, the application of the Coupled Eulerian-Lagrangian (CEL) method which has not been used yet to the modelling of roller compaction is presented. Typically used to study fluid-structure interactions, the CEL method, however, has been applied to other manufacturing processes such as metal cutting [2] and hot granular sheet forming [3]. Similarly to the ALE, this method involves both Eulerian and Lagrangian formulations in which the Eulerian part can be filled by the material undergoing large deformations, which avoid mesh problems when performing simulations involving high deformations. The application of the CEL method to the simulation of roller compaction was conducted using the Drucker-Prager/cap as model behaviour and the microcrystalline cellulose as material model. The obtained results of CEL simulations are compared to the measurements and to the ALE results. Figure 1 gives an overview of the predicted 3D density distributions under the roll and in the expansion zone
Mutualisation des capacités résiduelles de livraison de colis dans la logistique urbaine
No full textInternational audienceThe exponential growth of e-commerce has imposed new demand patterns on parcel logistics and delivery systems, particularly in urban environments. This challenges capacity planning for parcel delivery companies, often leading to overcapacity sizing of resources to meet this demand throughout the year. While the parcel delivery industry faces fluctuations in demand and underutilized capacity, dynamic resource allocation emerges as a potential solution for operational efficiency. This paper addresses this challenge across a network of regional hubs to meet fluctuating demand in parcel logistics. Through a sequential stochastic optimization algorithm, we aim to assess residual capacity in the network and optimize its usage to reduce operational costs, thereby improving the economic performance of delivery operations. Our approach incorporates adaptive decision-making at each decision period, leveraging insights from previous demand patterns and resource deployment effectiveness. First, numerical experiments demonstrate the benefits of our dynamic resource allocation strategy in using the residual capacity to minimize costs and enhance service responsiveness.La croissance exponentielle du commerce électronique a imposé de nouveaux modèles de demande aux systèmes de logistique et de livraison de colis, en particulier dans les environnements urbains. Cela pose un défi en matière de planification des capacités pour les entreprises de livraison de colis, qui se retrouvent souvent avec des ressources surdimensionnées pour répondre à cette demande tout au long de l'année. Alors que le secteur de la livraison de colis est confronté à des fluctuations de la demande et à une sous-utilisation des capacités, l'allocation dynamique des ressources apparaît comme une solution potentielle pour améliorer l'efficacité opérationnelle. Cet article aborde ce défi à travers un réseau de hubs régionaux afin de répondre à la demande fluctuante dans le domaine de la logistique des colis. Grâce à un algorithme d'optimisation stochastique séquentielle, nous visons à évaluer la capacité résiduelle du réseau et à optimiser son utilisation afin de réduire les coûts opérationnels, améliorant ainsi la performance économique des opérations de livraison. Notre approche intègre une prise de décision adaptative à chaque période de décision, en tirant parti des informations issues des modèles de demande antérieurs et de l'efficacité du déploiement des ressources. Tout d'abord, des expériences numériques démontrent les avantages de notre stratégie d'allocation dynamique des ressources dans l'utilisation de la capacité résiduelle pour minimiser les coûts et améliorer la réactivité du service
Photoluminescence evolution in APS-deposited YSZ:Eu3+ thermal barrier coatings: mechanisms and sensitivity to thermal history over 0–800 h isothermal exposure at 1100 °C
No full textInternational audienceThermal history coatings (THCs) deposited via Atmospheric Plasma Spray (APS) offer a promising solution for recording maximum equivalent temperature maps in high-temperature environments such as gas turbines. The sensitivity of an APS-deposited Eu3+-doped Yttria-stabilized Zirconia (YSZ) coating to thermal history through isothermal oxidation treatments at 1100 °C for durations ranging from 10 to 800 h was investigated. The evolution of photoluminescence intensity with exposure duration was evaluated and put in relation with structural (X-ray diffractometry) and microstructural (scanning electron microscopy with energy-dispersive spectroscopy) characterizations. A comparative analysis with compressed powder pellets was also conducted to isolate the effects of the deposition process and interactions with the substrate.Photoluminescence emission measurements revealed two distinct sensitivity regimes: (1) a rapid increase in intensity during the first 30 h, driven by crystallization, reduction of crystallographic defects, and particle growth, and (2) a significant intensity decline beyond 30 h, attributed to optical property modifications caused by substrate elements diffusion (Cr, Co) to the coating surface. These findings demonstrate the capability of APS-deposited YSZ:Eu3+ coatings to sense thermal history over extended durations of exposure, with mechanisms transitioning from crystallinity enhancement to substrate-induced effects. Those results are promising for the development of photoluminescent THCs with a capability for long-duration thermal history sensing
Unveiling how mitotic spindle orientation in 3D human colon organoids affects matrix displacements through a 4D study using DVC
No full textInternational audienceCell division is a major event in tissue homeostasis, enabling renewal and regeneration. In human colon, vertical division is mainly observed in the stem cell compartment while horizontal division is more frequent in the progenitor transit amplifying zone. To study cell division, the human colon epithelium represents a relevant model due to its rapid renewal and high number of mitoses. Studying live mechanical interactions between the epithelium and its matrix in vivo is challenging due to the lack of suitable methods. Colon organoids seeded in Matrigel are good models because they recapitulate the organization and properties of tissue architecture. This culture set-up allows to study the displacements of the matrix around the organoid. We studied the impact of cell division within the human colonic epithelium on the extracellular matrix. We validated an original experimental and analytical process with 3D time-lapse confocal microscopy to follow cell division and matrix displacements, on which we performed a 4D Digital Volume Correlation. Depending on the orientation of the mitotic spindle, cell division affects the matrix differently. Vertical division causes a predominantly uniaxial displacement of the matrix, while horizontal division involves a multiaxial and wider displacement
Mechanistic insights on hydrazones synthesis: a combined theoretical and experimental study
No full textInternational audienceHydrazone derivatives of isoniazid have demonstrated potential as anti-tubercular agents. While previous studies have predominantly focused on their biological activity, existing literature lacks both experimental and computational studies on the mechanisms and kinetics of their syntheses. This study aims to address this gap by employing a combined computational and experimental approach to investigate the hydrazone synthesis from isoniazid and isophthalaldehyde through competitive-consecutive reactions. Density functional theory (DFT) calculations were performed to explore the possible reaction pathways and their energy profiles in both the gas phase, and with solvation. Experimental kinetic studies were conducted in a jacketed batch reactor using ethanol/water and dry acetonitrile to support the computational findings by assessing the impact of solvents on reaction dynamics. The computational results indicate that water has a catalytic effect on the reaction, not only by assisting in the rate-limiting step but also by avoiding high-energy isomerizations, required in its absence. Experimental kinetics in dry acetonitrile demonstrated a very slow reaction rate, while the ethanol/water system achieved higher conversion rates in the same amount of time, aligning with the computational findings. Experimentally determined activation energies closely matched the value predicted computationally
Evaluation of an Improved Filtering Method for Strain Measurement at High Temperatures Using 2D-DIC
No full textInternational audienceBackground The Two-Dimensional Digital Image Correlation (2D-DIC) method is widely used as a non-contact full-fieldkinematic measurement, but it presents significant errors related to temperature effects including the image con- trast andheat waves. Consequently, results of mechanical displacement or strain measured by the 2D-DIC method, especially strainsin the elastic domain of materials, is significantly dispersed.Objective The aim of this study is to propose a very simple 2D-DIC method, using commercial DIC software with no needof additional storage to accurately measure strain and displacements at high temperatures, typically at the hot metal formingtemperatures, from 400 ◦C to 750 ◦C.Methods This study demonstrates the influence of temperature effects (radiation and heat waves) on strain measurementsobtained with the 2D-DIC method in the elastic regime (ε < 0.05) of the TA6V titanium alloy material at high tempera-tures. Furthermore, the strain measurement errors at different temperatures were characterized by the Background OrientedSchlieren technique (BOS). Correction methods using temperature-dependent low-pass filters for strain measurement errorsare suggested.Results The correction methods allow separating mechanical strain fields and strain measurement errors caused by tem-perature effects. The efficiency of the correction methods is demonstrated by identifying the Young’s modulus (E) and theThermal Expansion Coefficient (TEC) of the TA6V. After corrections, E and the TEC of the TA6V are close to the referencevalues found in the literature. Conclusion: The coefficient R2 from the linear regression method to determine the Young’smodulus from tensile test at 600 ◦C increases from 0.783 to 0.989, revealing the great potential of using the improved-2D-DIC method for full-field kinematic measurements of mechanical tests at high temperatures
Introduction to the Minitrack on Disaster Information, Resilience, for Emergency and Crisis Technologies
No full textInternational audienceThe DIRECT minitrack is a part of the Digital Government Track. The DIRECT minitrack in HICSS-58 continues the tradition of delivering a high-quality venue for scholars scrutinizing all aspects of design, development, implementation, analysis, operation, evaluation and use of information systems and ICT to strengthen societal resilience. Over the years this minitrack have received interesting, innovative articles and breakthrough visions on disaster management and response, technology supported disaster management and resilience. The DIRECTminitrack is dedicated to being a meeting point for researchers in the broader topic of information technology and information systems for crisis management and security, and focuses on how technologies, information management, data science and artificial intelligence can contribute to support emergency management as part of digital government