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Polypropylene/bis(benzoxazolyl)stilbene mechanochromic blends, an attractive feature for colorimetric strain detection
No full textInternational audienceBis(benzoxazolyl)stilbene (BBS) incorporation into polypropylene (PP) host leads to a mechanochromic polymer composite blend whose color can change (from green to blue) under UV excitation with mechanical strain. The aim of this study is to prove the feasibility of mechanical strain control by colorimetry on such a mechanochromic blend and to understand the mechanical, chemical and radiative behaviors differences between stretched and unstretched parts. The first part, dedicated to mechanical and radiative characterizations, leads to the choice of the dye concentration of 1%wt, where mechanical properties are preserved and photoluminescence output is optimized. Then, a colorimetric measurement system is set-up and show remarkable potential for strain evaluation by marking the necking initiation and the beginning of the first plastic flow. Moreover, the change in luminescence emission is concomitant with mechanical necking and continues during the first plastic flow. Secondly, the RGB image treatment analysis developed here involves the calculation of the image ratio of the green channel over the blue one. It promises remarkable capacities to detect and localize the very beginning of mechanical break on polymeric 2D structures
Incorporating hydrothermal liquefaction into wastewater treatment – Part II: Characterization, environmental impacts, and potential applications of hydrochar
No full textInternational audienceHydrothermal liquefaction (HTL) is a promising technique for renewable biofuel (biocrude) production from municipal sludge. However, its solid byproduct, hydrochar, requires sustainable management for further resource recovery and pollution control. This study comprehensively assessed the properties, environmental influences, and possible utilizations of hydrochar generated from mixed sludge (MS). With the increase of HTL reaction temperatures (290–360 °C) and residence time (0–30 min), the dry-weight contents of ash and fuel ratio increased from 10.5% and 0.1 in MS to 48.7–68.5% and 0.4–0.7 in hydrochar, respectively. However, the dry-basis contents of volatile matter, carbon, and higher heating value sharply decreased to 18.7–35.9%, 22.9–37.3%, and 8.6–16.0 MJ/kg, respectively. The leaching risks of inorganic contaminants from hydrochar were limited and controllable in various scenarios. Hydrochar performed more stable combustion than sludge, but its high ash contents and alkali index (0.28–0.72 kg/GJ) implied high risks of slagging and fouling. Hydrochar has a good potential for carbon sequestration due to low O/C ratios (<0.2) and improved recalcitrance index (0.43–0.48). Benefiting from intrinsic metals (e.g., Ca and Fe), catalytic hydrochar graphitization was feasible at a moderate temperature (1200 °C). Although hydrochar was restricted from land application for heavy metals accumulation, it is promising for metals and nutrient recovery. It has a total phosphorus (P) of 7.2–8.5% by weight, and thus P recovery is critical and necessary for mitigating environmental challenges and global P scarcity. Overall, this study contributed to the state-of-the-art in waste-to-resource development and cleaner production
Adsorbants à base de phosphates pour l'abattement des métaux lourds en phase gazeuse
No full textEnvironmental standards for emissions of pollutants into the air are becoming increasingly restrictive, with new emission thresholds that must complied with. It is therefore necessary to develop and/or improve current techniques to remove heavy metals. This thesis aims to develop a calcium phosphate sorbent with controlled properties to remove heavy metals from the gas phase at high temperature (> 240°C). Although the process from getting the removal of heavy metals at low temperature ( 700°C). Experimental data on cadmium adsorption were modelled using a mathematical approach based on the kinetics of adsorption processes and mass transfer phenomena. The model was used to predict the dynamic of cadmium adsorption on hydroxyapatite using breakthrough curves describing the cadmium concentration profile as a function of time. This work has shown that the synthesised hydroxyapatites have interesting surface, flow, thermal and thermomechanical properties, showing their possible application at high temperatures at industrial scale in a waste incineration unit.Les normes environnementales concernant les émissions de polluants dans l'air deviennent de plus en plus restrictives avec de nouveaux seuils d'émission à obligatoirement respecter. A cet effet, il est nécessaire de développer ou d'améliorer les techniques actuelles d'abattement des émissions de métaux lourds à haute température (> 240°C). Ce travail de thèse se place dans cette problématique et a pour objectif le développement d'adsorbant à base de phosphates de calcium aux propriétés contrôlées permettant l'élimination des métaux lourds en phase gazeuse à haute température. Si les procédés d'élimination de ces métaux lourds à basse température ( 240°C) restent rares. Dans un premier temps, différentes synthèses de phosphates de calcium ont été réalisées afin d'identifier l'influence des conditions opératoires sur les propriétés physico-chimiques et thermiques du solide. Le rapport liquide/solide et la vitesse d'agitation se sont avérés comme les paramètres les plus influents sur les propriétés finales du produit obtenu. Une hydroxyapatite avec une surface spécifique comprise entre 90 et 100 m2 /g a été obtenue. Sur la base des résultats obtenus, l'hydroxyapatite retenue pour les essais d'adsorption du cadmium ou du plomb en lit fixe à l'échelle laboratoire a été celle présentant les meilleures caractéristiques en termes de stabilité thermique, physique et chimique. Néanmoins, ce manuscrit couvre en grande partie les travaux sur l'adsorption du cadmium. Une deuxième hydroxyapatite fournie par l'industriel (surface spécifique :119 m2 /g) a également été utilisée pour les essais d'adsorption. Les différents tests d'adsorption ont été réalisés en faisant varier des paramètres tels que le débit de gaz (1-3 L/h), la température (700-1000°C), le temps de contact, la concentration initiale du métal lourd et la hauteur du lit de poudre d'adsorbant (0,5-1,5 cm). Les résultats ont montré la capacité de ces adsorbants à capter les métaux lourds sous des contraintes thermiques (T > 700°C). Les données expérimentales d'adsorption du cadmium ont ensuite été modélisées à l'aide d'un modèle mathématique basé sur la cinétique des processus d'adsorption, et les phénomènes de transfert de matière. Il a permis de prédire la dynamique d'adsorption du cadmium par l'hydroxyapatite à travers les courbes de percée décrivant le profil de concentration du cadmium en fonction du temps. Ce travail a démontré que les hydroxyapatites synthétisées présentent des propriétés de surface, d'écoulement, thermiques et thermomécaniques intéressantes permettant d'envisager leur application à haute température à l'échelle industrielle dans une unité d'incinération des déchets
Etude et adaptation des propriétés des noirs de carbone récupérés à partir de pneumatiques usagés dans un contexte d'économie circulaire
No full textThe management of end-of-life tyres remains a critical issue, given the regulations requiring used tyres to be recovered, reused and recycled. Carbon black is a manufactured product of petrochemical origin whose production process is energy-intensive and polluting, it is the main mechanical reinforcement filler of rubber in tyres. Recovering carbon black and reintroducing it into the formulation of new tyres is a major challenge for the circular economy. Currently, only chemical (toxic organic solvents) or thermochemical techniques are capable of isolating carbon black from vulcanised rubber. In the manufacture of tyres, carbon blacks ensure mechanical strength, while the increasing addition of silica reduces rolling resistance and increases service life. At the end of the pyrolysis process in the presence of steam, the elastomer is degraded and the solid phase is made up of carbon black, silica and ash (zinc, sulphur). In this thesis, the physical and chemical properties of carbon black recovered from model tyre tread mixtures are analysed using several complementary techniques. At present, recovered carbon black does not have properties close enough to those of the original material that is used in the elastomer industry, because it is not sufficiently dispersed. In order to better assess the modifications induced by the thermochemical process, as well as the role of ash from the formulation, physical techniques such as X-ray diffraction, which shows the fraction of the additional carbon deposit, have been used. Chemical techniques such as gas adsorption and desorption at programmed temperatures have highlighted the change in porosity and the gain in oxygen-containing surface functional groups. This made it possible to differentiate more clearly between the original N330 carbon black and the recovered carbon black. Other experiments focusing on the dispersibility of the recovered material in various media highlighted the complexity of the material's behaviour. In order to improve the incorporation of the recovered carbon blacks into the elastomer, functionalisation tests were carried out by depositing crystalline nano-cellulose and reducing the oxygen-containing surface functional groups by hydrogen treatment. These results represent a major contribution to the understanding of the physico-chemical properties of recovered carbon blacks, and form part of a virtuous objective to promote the circular economy and reduce pollutant emissions.La gestion des pneumatiques en fin de vie reste un sujet critique en raison des réglementations imposant la récupération puis le réemploi et la valorisation des pneumatiques usagés. Le noir de carbone, un produit manufacturé d'origine pétrochimique et dont la voie de production est énergivore et polluante, constitue le renfort mécanique principal du caoutchouc dans le pneumatique. Sa récupération et sa réintroduction dans la fabrication de nouveaux pneumatiques constituent un enjeu d'économie circulaire. Seules des techniques chimiques (solvants organiques toxiques) ou thermochimiques sont à même d'isoler le noir de carbone du caoutchouc vulcanisé. Dans la fabrication des pneumatiques, la tenue mécanique est assurée par les noirs de carbone tandis que l'adjonction croissante de silice réduit la résistance au roulement et augmente la durée de vie. A l'issue du procédé de pyrolyse en présence de vapeur d'eau, l'élastomère est dégradé et la phase solide est constituée de noir de carbone, de silice et de cendres (zinc, soufre). Dans cette thèse, les propriétés physiques et chimiques des noirs de carbone récupérés dans des mélanges modèles sont analysées avec plusieurs techniques complémentaires. En effet, le noir de carbone récupéré n'a actuellement pas les propriétés suffisamment proches du matériau d'origine pour servir l'industrie des élastomères car sa dispersion est limitée. Afin de mieux évaluer les modifications induites par le procédé thermochimique mais aussi le rôle des cendres provenant de la formulation, les techniques physiques comme la diffraction des rayons X, qui montre la fraction du dépôt carboné supplémentaire, ont été utilisées. Des techniques chimiques comme l'adsorption de gaz ou la désorption en température programmée ont mis en évidence la modification de porosité et le gain de fonctions oxygénées de surface. Il a ainsi été possible de différencier plus nettement le noir de carbone N330 d'origine et le noir de carbone récupéré. D'autres expériences axées sur la dispersibilité du matériau récupéré dans divers liquides ont mis en évidence la complexité du comportement du matériau. Afin d'améliorer l'incorporation des noirs de carbones récupérés dans l'élastomère, des tests de fonctionnalisation par dépôt de nano-cellulose cristalline et par réduction des fonctions oxygénées par traitement hydrogène ont été réalisés. L'ensemble des résultats constitue une contribution importante à la compréhension physico-chimique des noirs de carbone récupérés et s'insère dans un objectif vertueux d'économie circulaire et de réduction des émissions polluantes
Developing a Recommender System for Frailty Prevention: Addressing Challenges of Data Collection and User Interface Design
No full textcopyright IEEEInternational audienceFrailty presents a significant global health challenge for older adults, necessitating effective interventions to support healthy aging. Technology-based solutions, particularly recommender systems, hold promise in addressing frailty prevention. This paper presents Senselife platform for service recommendation dedicated for frailty prevention.We delve into the challenges associated with developing an engaging and user-friendly recommender system specifically tailored for frailty prevention. Key challenges we address include implementing effective data collection strategies and designing user-centered interfaces. Our proposed recommendation platform leverages self-evaluation to deliver personalized recommendations, with the goal of enhancing the functional capabilities of older adults. By aligning the available services within the elderly environment with the demands they face, our solution tackles the complexities of managing frailty in this population.Throughout this study, we elucidate the construction of our surveys, the main source of data for Senselife and the design considerations behind our user interfaces, highlighting our efforts in overcoming the unique challenges associated with systems dedicated to elderly usage
Isoconversional and distributed activation energy models for the kinetic study of biomass fast devolatilization based on Mass Spectrometry data
No full textInternational audienceThe fast pyrolysis process allows the transformation of woody biomass particles mainly into bio-oil. This liquid, more or less viscous, is composed of hundreds of organic compounds, likely to be valorized as liquid biofuel or organic products for the chemical industry. The modeling of microkinetics and more particularly the determination of kinetic parameters called 'intrinsic' is a major challenge to establishing the optimal operating conditions, thus maximizing the yields of desired products. The objective of this work is to produce experimental data sets describing the reactivity of woody biomasses under kinetic control using a conventional analytical tool: a micropyrolyser coupled to a mass spectrometer (Py-MS) and propose two reactivity models to predict the fast devolatilization of biomass.For this purpose, the Py-MS was used, allowing the online detection and identification of molecules released during the pyrolysis process. Thus, in addition to the whole biomass devolatilization, biomass fractions were identified directly by extracting the appropriate m/z ratios. However, the challenge associated with online detection is represented in the time lag related to transport phenomena occurring between the reactor and the detector. That is why a method was developed to derive the real-time devolatilization profile of biomass while it is pyrolyzed in a constant-temperature environment.For the kinetic study, both empirical approaches using the isoconversional method and distributed activation energy model (DAEM) based on the first time on the abundance of released ions were used for the prediction of biomass fast pyrolysis. The most common differential isoconversional method combined with real-time temperature histories of the sample was then applied to real-time devolatilization profiles to interpret and model “primary” mechanisms of biomass devolatilization (Figure 1a). It was found that non-correcting heat and mass transfer limitations lead to high kinetics inaccuracies and suppress the reactions occurring during sample heating. Isoconversional Eα dependencies obtained in the absence of heat and mass transfer limitations for biomass and their main components (e.g., holocellulose and lignins) highly varied with conversion, confirming the multi-step nature of the fast pyrolysis process. Each isoconversional function (e.g., Eα and lnÃα) was then parametrized with 6 parameters by the least-squares method, and both were used to predict the biomass devolatilization (Figure 1a). On the other hand, a two-gaussian DAE model was applied (Figure 1b) and confirmed the occurrence of two consecutive devolatilization stages
Synthesis of flavonoid derivatives precursors of active pharmaceutical ingredients by mechanical chemistry: Eco-friendly process
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Drilling of multi-material stacks for the assembly of aeronautical structures: from the characterization of the cutting mechanisms to the development of Smart drilling techniques
No full textInternational audienceThe assembly process in the aeronautical sector mostly uses mechanical fastening. It requires the drilling of hundreds of thousands of fastening holes. As these holes are critical areas for the assembly fatigue life, the drilling operation is a key point. The fatigue performance of a machined surface can be correlated to the surface integrity. But the correlation between the machining process and the surface integrity seems very broad and complex.To understand the impact of the drilling process on the surface integrity, a multi-scale approach was developed. The characterization of the local cutting mechanisms in drilling allows to better model the thermomechanical loading on the surface. Investigations on drilled holes show the complexity of the characterization of the surface integrity. Some results on Aluminum or Titanium alloys will be presented. The surface integrity was studied through surface roughness measurements, microstructure and hardening analysis and residual stress assessment. An innovative Hole Opening Comparative Technique was set up to assess the residual stress state. Fatigue tests were also conducted, showing the major impact of the strain hardening of the hole subsurface, associated with a residual stress state. Significantly different results can be obtained, depending on the material, but also on the process operation. These results on various studies show that the control of the drilling operation can be an important issue. Smart drilling techniques are being developed in the literature. The approach considered in our work was to combine the development of digital twins of the drilling operation, based on the numerous drilling models that were developed, with the consideration of the social acceptability of this technology in the industrial environment
Preface of the proceedings ICDSST 2023 : 9th International Conference on Decision Support System Technology
No full textInternational audienceThis thirteenth edition of the EWG-DSS Decision Support Systems published in the LNBIP series presents a selction of high-quality papers from the 9th International Conference on Decision Support System Technology (ICDSST 2023), held in Albi, France, during May 30 - June 1, 2023, with the main theme "Decision Support Systems in AN Uncertain World: The Contribution of Digital Twins". This event was organized by the Euro Working Groupe on Decision Support Systems (EWG-DSS) in collaboration with the University of Toulouse 1 - IMT Mines Albi