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Mechanical and Thermal Properties of Sustainable Composite Building Materials Produced by the Reprocessing of Low-Density Polyethylene, Biochar, Calcium Phosphate, and Phosphogypsum Wastes
No full textInternational audienceThis paper presents the results of the experimental and analytical studies of the mechanical and thermal properties of laterite composites mixed with reprocessed low-density polyethylene waste (LDPE), calcium phosphate (CaP) and phosphogypsum wastes, and biochar to form brick composites. Bricks with mixtures of 20% by volume LDPE, 15% by volume CaP, and 15% by volume gypsum were shown to have excellent compressive strength, flexural strength, and fracture toughness. The composites with 1% by volume LDPE and 15% by volume biochar had the best blend of mechanical properties, such as flexural strength and fracture toughness, after sintering for ∼24h. There was a linear association between the strength and the weight loss of the bricks. Scanning electron microscopy and optical microscopy images revealed evidence of crack bridging by LDPE particles. The laterite–LDPE composite mixed with 5%, 10%, and 15% by volume biochar had sintering temperatures of ∼850°C, ∼720°C, and ∼710°C, respectively, after undergoing softening, cold crystallization, and cooling
Modelling powder compaction with consideration of a deep grooved punch
No full textInternational audienceIn this work a modelling approach for predicting density distribution in the vicinity of two facing grooves on a parallelepiped compact surface, is developed and results are validated using X-ray tomography. An experimental hybrid procedure is proposed to calibrate Drucker-Prager Cap model material parameters which are numerically validated and considered for FEM compaction simulation of grooved specimen using Arbitrary Lagrangian Eulerian method (ALE). Results of the predicted density show high values under the groove and low values on its flanks and shoulders. Similar findings were observed in the literature. Additionally, a strong density gradient between the facing grooves is predicted and validated, demonstrating that the calibrated model achieved good agreements with the measurements.The proposed hybrid calibration procedure could be used for other shape and size die not benefiting from radial instrumentation. Moreover, the ALE approach demonstrated its robustness in solving die powder compaction in presence of strong mesh distortions
A Reinforcement Learning Powered Digital Twin to Support Supply Chain Decisions
No full textInternational audienceThe complexity of making supply chain planning decisions is growing along with the Volatility, Uncertainty, Complexity and Ambiguity of supply chain environments. As a consequence, the complexity of designing adequate decision support systems is also increasing. New approaches emerged forsupporting decisions, and digital twins is one of those. Concurrently, the artificial intelligence field is growing, including approaches such as reinforcement learning. This paper explores the potential of creating digital twins with reinforcement learning capabilities. It first proposes a framework for unifying digital twins and reinforcement learning into a single approach. It then illustrates how this framework is put into practice for making supply and delivery decisions within a drug supply chain use case. Finally, the results of the experiment are compared with results given by traditional approaches, showing the applicability of the proposed framework
Vers une chaîne logistique humanitaire hyperconnectée
No full textIn the aftermath of major disasters, such as the 2004 tsunami in the Pacific Ocean or the 2010 earthquake in Haiti, the quality of the aid delivered to assist the affected population was the subject of great attention and criticism. Saving human lives and relieving suffering depend on the capacity of humanitarian organizations to mobilize resources, and specifically to organize the logistics of relief items from sourcing points to distribution points. However, inefficient and unsustainable activities call into question the way humanitarian supply chains are organized. Given this reality, and while an active branch of research is striving to achieve localised improvements, we are taking the opposite view and and explore a more holistic and profound reform. The ambition of this research work is to redesign the foundations of the humanitarian system by ideating a new version of humanitarian supply chains.In this perspective, we focused on a new logistics paradigm known as Physical Internet, which has recently emerged as a way to address the symptoms of unsustainability associated with commercial logistics. The Physical Internet is a global concept that envisages a new way for goods to be moved, supplied, designed, and used in the perspective of making logistics and supply chains more efficient, sustainable, smart, agile, adaptable and scalable. To do so, it suggests a new logistics structure based on open hubs and cooperative platforms for both data and material flows. Also, it aims to strengthen the interconnection between supply chain actors by means of shared and standardized resources, equipment and facilities. The main idea of this innovative research project is to explore the applicative potentialities of this new logistics paradigm to humanitarian supply chains. This original association has been under-studied so far and only by very few researchers. To this end, several research phases were carried out leading to three main contributions. First, the proposition of an hyperconnected humanitarian supply chain paradigm in light of current practices and inspired from the key concepts of the Physical Internet. This conceptual contribution is complementary to very first discussions on the topic and differentiates the method used for framing the ideation phase. New Physical Internet-oriented practices were designed from the recognized performance success factors of supply chains and humanitarian supply chains. The second contribution is the design of a simulation-based experimental approach to evaluate the relevance on performance of this new paradigm envisioned for humanitarian supply chains. Thus far, the novelty of the topic has remained at the conceptual level and no experiments have been conducted so far. This methodological contribution is one of the first of its kind, generic enough to be used in other contexts and requiring the development of a rigorous, relatively complete and novel approach to the humanitarian supply chain model. Thirdly, an applicative contribution is proposed through the design and conducting of an experiment using a field-based case study. This case study is based on the network architecture and main relief activities of the Indonesian Red Cross in the context of a historical earthquake that hit Indonesia in the past. Results obtained from the simulation indicate major positive effects of the tested Physical Internet-oriented practices compared to the current strategies. Significant reductions in both supply lead times and cost were demonstrated, as well as better use of resources.Après plusieurs catastrophes majeures, le niveau de qualité de l'aide apportée aux populations touchées a attiré l'attention et généré des critiques. L'enjeu est de taille puisque des vies humaines sont en jeu et dépendent de la capacité des Organisations Humanitaires (OH)s à mobiliser des ressources. Plus particulièrement, en ce qui concerne la logistique des articles de première nécessité à acheminer. Cependant le fonctionnement associé a été jugé inefficace et non durable remettant en question la manière dont les chaînes d'approvisionnement humanitaires sont aujourd'hui gérées. Partant de ce constat, et alors qu'une branche active de la recherche s'évertue à réaliser des améliorations localisées, nous en prenons le contre-pied et explorons une refonte plus holistique et profonde. Par conséquent, l'ambition de ce travail de recherche est de redéfinir les fondements du système humanitaire en imaginant une nouvelle version des chaînes d'approvisionnement humanitaires. Dans cette perspective, nous nous sommes d'abord intéressés à un nouveau paradigme logistique connu sous le nom d'Internet Physique, récemment apparu comme un moyen de traiter les symptômes de non-durabilité que présentent les chaînes d'approvisionnement plutôt commerciales. L'Internet Physique est un concept global qui envisage une nouvelle façon de déplacer les marchandises dans le but de rendre la logistique et les chaînes d'approvisionnement plus efficaces, durables, intelligentes et agiles. L'objectif de ce projet de recherche est d'explorer les potentialités d'application de ce nouveau paradigme sur les chaînes d'approvisionnement humanitaires. Cette association originale a été peu étudiée jusqu'à présent et seulement par un nombre réduit de chercheurs. À cette fin, plusieurs phases de recherche ont été menées et ont abouti à trois contributions principales. Premièrement, la proposition d'un paradigme de chaîne d'approvisionnement humanitaire hyperconnectée à la lumière des pratiques actuelles et inspiré des concepts de l'Internet Physique. Cette contribution conceptuelle est complémentaire aux premières discussions sur le sujet et se différencie par la méthode utilisée pour encadrer la phase de création. En effet, nous ne sommes non pas partis des défis rencontrés, mais des facteurs clés de performance des chaînes d'approvisionnement en général et plus spécifiquement humanitaires. La deuxième contribution est la conception d'une approche expérimentale orientée autour de la simulation afin d'évaluer la pertinence de ce nouveau paradigme envisagé pour les chaînes d'approvisionnement humanitaires. Jusqu'à présent, la nouveauté du sujet a orienté les discussions sur des aspects plus conceptuels et aucune expérience n'a encore été menée. Cette contribution méthodologique se veut générique pour être utilisée dans d'autres contextes. Elle a aussi nécessité le développement d'un modèle à la perspective nouvelle et complète des chaînes d'approvisionnement humanitaires. Troisièmement, une contribution applicative est proposée au travers de la conception et la réalisation d'une expérience utilisant un cas d'étude métier. Ce cas s'inspire de l'architecture du réseau logistique actuel et des principales activités de secours menées par la Croix-Rouge indonésienne. Les résultats obtenus à partir de la simulation indiquent des impacts positifs et majeurs quant aux propositions de pratiques inspirées de l'Internet Physique ceci en comparaison des stratégies actuelles. Des réductions significatives des délais d'approvisionnement et des coûts ont ainsi pu être démontrées ainsi qu'une nette optimisation dans l'utilisation des ressources
Use of Physics of Decision to assess how COVID-19 impacted air pollution
No full textInternational audienceThis article focuses on the question of the impact of the COVID-19 crisis on air pollution. The chosen approach is based on the principle of “Physics of Decision” (POD), which considers: (i) the performance of a system as a physical trajectory within the framework of its performance indicators, (ii) risks or opportunities (potentialities) as forces that may deviate that trajectory, and (iii) benefits or damages (actualities) as concrete deviations of the performance trajectory. The daily data about the air pollution in Paris area (France) has been gathered for eight years (2014-2021) and three main performance indicators have been chosen. Then, the performance trajectory of each year has been plotted and the expected trajectories of 2020 and 2021 have been guessed from the previous ones. The deviation between the expected and actual trajectories of 2020 and 2021 have been assessed, and using physics and motion laws, evaluated as a deviation force
Simulation of sonoreators accounting for dissipated power
No full textInternational audienceA sonoreactor is a volume of liquid enclosed by a vessel and in contact with one or more ultrasonic sources, generally piezoelectric transducers. As such, it pertains to acoustics problems but globally consistent models of such systems is still lacking. The liquid generally undergoes inertial cavitation, which renders linear acoustics invalid, even if the latter accounts for bubbles. A nonlinear acoustics model is therefore necessary to describes acoustic waves in the cavitating liquid, accounting properly for the mechanical energy dissipated by bubbles into heat. As the numerical resolution of such models at the spatial and temporal scales involved in sonoreactors experiments appears yet unfeasible, we proposed a decade ago a reduced, albeit nonlinear model which results in a nonlinear Helmholtz equation. Once coupled to physics of elastic solids and piezo-electricity, a complete sonoreactor can be modelled and quickly solved, each part obeying a mechanical energy conservation equation, which we recall here. By construction, our model conserves energy, allowing additions. Three examples are proposed, for which dissipated and active power are systematically computed. For the first configuration, comparison with experiment is done and reveals that our cavitating liquid model overestimates the consumed electrical power by a two-fold factor. The second raises the issue of modelling correctly sonoreactors described in the literature. The third gives prediction on a new type of transducer, allowing radial energy transfer by lateral boundaries
Incorporating hydrothermal liquefaction into wastewater treatment – Part I: Process optimization for energy recovery and evaluation of product distribution
No full textInternational audienceThe treatment of significant amounts of municipal sewage sludge requires novel and efficient technologies. This study evaluated hydrothermal liquefaction as a means to sustainably convert sludge waste into a renewable energy source – biocrude, which can mitigate both environmental and energy-related challenges. Response surface methodology was employed to investigate the effects of reaction temperature (290–360 °C) and residence time (0–30 min) on product yield and biocrude quality. Both the highest and the lowest reaction temperature or residence time had negative effects on biocrude yield and energy recovery (ER), while high reaction severities improved biocrude quality. Under optimized conditions (332 °C for 16.9 min), biocrude yield (48.9%, dry ash-free) and ER (70.8%) were maximized. Biocrude composition followed the order of N-heterocycles > O-heterocycles > hydrocarbons, while nitrogenous compounds reduced, and hydrocarbons increased with reaction temperature. More distillable fractions in biocrude were also produced at higher reaction severities. The possible reaction pathways of biocrude formation were discussed and updated to include catalytic effects on inherent metals and Brønsted (acidic and basic) sites. The high content of O (7.8–13.1%), N (4.4–4.9%), and TAN (48.6–63.6 mg KOH/g) suggested the necessity of biocrude upgrading. Separating and recycling trace metals (e.g., 497–656 mg/kg Fe) from biocrude are necessary to relieve upgrading challenges. C, N, and P were mostly distributed into HTL biocrude, aqueous, and hydrochar, respectively, allowing their recovery. Most metals were concentrated in hydrochar. The results contribute to the advancement of the state of the art in biorefinery, which will guide the design of full-scale HTL sludge treatment systems combining resource recover
Generation of subharmonics in acoustic resonators containing bubbly liquids: A numerical study of the excitation threshold and hysteretic behavior
No full textInternational audienceIn this paper we study the generation and behavior of subharmonics in a bubbly liquid confined in an acoustic resonator, through numerical simulations carried out at finite-amplitude acoustic pressure. Several configurations in terms of resonator length and driving frequency are considered here. Our results show that these frequency components, created from a higher-frequency signal at the source (ultrasound), are due to the nonlinearity of the medium at high acoustic-pressure amplitude and to the configuration of the resonator (geometry and boundaries). We also show that they have an amplitude-threshold dependence, which is in concordance with the literature. The response of these subharmonics to different sequences of pressure amplitudes also reveals the hysteretic nature of the bubbly liquid
Experimental measurements and modelling of vapor-liquid equilibria for four mixtures of 2,3,3,3-tetrafluoropropene (R1234yf) with 1,1,1,2-tetrafluoroethane (R134a) or 1,1-difluoroethane (R152a) or trans-1-chloro-3,3,3-Trifluoropropene (R1233zd(E)) or 2-Chloro-3,3,3-trifluoropropene (R1233xf)
No full textErratum in “Experimental measurements and modelling of vapor-liquid equilibria for four mixtures of 2,3,3,3-tetrafluoropropene (R1234yf) with 1,1,1,2-tetrafluoroethane (R134a) or 1,1-difluoroethane (R152a) or trans-1-chloro-3,3,3-Trifluoropropene (R1233zd(E)) or 2-Chloro-3,3,3-trifluoropropene (R1233xf)”. DOI : https://doi.org/10.1016/j.ijrefrig.2022.07.010International audienceIsothermal vapour-liquid equilibrium (VLE) for four binary systems involving R1234yf (R1234yf + R134a, R1234yf + R152a, R1234yf + R1233zd(E) and R1234yf + R1233xf) were measured at temperatures from 278.15 to 348.15 K. The experiments were conducted by means of a "static-analytic" apparatus with phase analysis via gas chromatography, with resulting uncertainties of 0.6 K for temperature, 8 kPa for pressure and a maximum of 0.007 for vapour and liquid mole fractions. The main advantage of the equipment is that vapour and liquid samples are taken from vapour and liquid phase by two capillary samplers (ROLSI®). The Peng Robinson Equation of state is considered to represent the experimental data. If possible, comparison between the new experimental data and prediction with REFPROP 10.0 software are realized
Supported Metal Single-Atom Thermo-Catalysts for Reforming Reactions
No full textInternational audienceIn line with many efforts of producing environment-friendly substitutes for fossil-fuel-based compounds (fuels and chemicals), syngas is getting more and more attention. Nowadays, syngas can be produced from various sources via reforming processes. This chapter highlights recent advances in supported metal single-atom catalysts (SACs) devoted to reforming processes, including methane, hydrocarbon, and alcohol reforming. For each process, the basic thermodynamic aspects and main challenges are addressed. Experimental and theoretical calculations reveal the role of the downsizing of active phase from nanoparticles to sub-nanoparticles (clusters and single atoms) in reforming catalysis science. It consists in the lowering of energy barriers to be able to select reaction pathways toward desired syngas products as well as to inhibit/limit carbon deposition