A stochastic model based on Gaussian random fields to characterize the morphology of granular objects

International audienceThe geometrical modeling of granular objects is a complex challenge that exists in many scientific fields, such as the modeling of granular materials or rocks and coarse aggregates with applications in civil, mechanical, and chemical engineering. In this paper, a model called SPHERE (Stochastic Process for Highly Effective Radial Expansion) is proposed, which is based on the deformation of an ellipsoid mesh using multiple 3D Gaussian random fields. The model is designed to be flexible (full control over 2D and 3D morphological properties of granular objects), ultra-fast (over 1000 aggregates in less than 5 s), and independent of the mesh and base shape used (as long as it is a star-shaped object). The flexibility of the model and its ability to reflect real data is illustrated using images of latex nanoparticle aggregates. Using 2D measurements on images from a morphogranulometer, a method based on the SPHERE model is proposed to estimate the 3D morphological properties of aggregates. A multiscale optimization process is applied, in particular using a partial reconstruction of 2D shapes from elliptic Fourier descriptors, in order to best reproduce the shape, angularity and texture of the aggregates using the SPHERE model. Validation of the method on 3D printed data shows relative errors of less than 3% for all measured 2D and 3D morphological characteristics, and validation on a population of synthetic objects shows relative errors of less than 6%. The results are compared and discussed with those obtained using other models based on overlapping spheres and show consistency with previous work. Finally, suggestions for improvement are given

Scenario-based Optimization to Address Ergonomic Challenges in Assembly Line Balancing

International audienceAssembly lines are key manufacturing systems, but they often face issues like operation time variability or ergonomic risks for workers. These challenges lead to operational inefficiencies, including a rise in musculoskeletal disorders (MSDs), and increased economic costs due to absenteeism and worker compensation. This work aims to help make the workplace more efficient and cost-effective by improving worker conditions. Moreover, in addition to the operational difficulties involved, the variability also complicates the accurate assessment of a worker's physical strain.We introduce a new strategy for scenario-based optimization of the assembly line balancing problem, modeling ergonomics with a fatigue and recovery criterion. Here, operation times can vary according to different scenarios, each associated with a probability of occurrence. Our objective is to minimize the fatigue level of workers for a given percentage of scenarios. To achieve this goal, we propose an Integer Linear Programming (ILP) approach that prioritizes worker health under fixed economic conditions. An Iterative Dichotomic Search algorithm is used to solve the problem, and a numerical example is presented.Our method is a new approach that uses variable operation times to better align with real-world assembly line uncertainties. To the best of our knowledge, our model is the first to deal with ergonomics in cases with variable operation times for manual workers, thus enhancing its practical applicability and effectiveness in real-world industrial settings. Practitioners benefit from our model’s adaptability to operation variations, offering practical solutions for decision-making and enhanced operational management

Cybersécurité. Qui fait quoi ? Comment se protéger ?

National audienceL'Université pour Tous d'Aurec-sur-Loire organisait une conférence sur le thème : "Cybersécurité : comment se protéger ?"A cette occasion, Guillaume Muller, enseignant chercheur à l'École des Mines de Saint-Étienne, et Philippe Beaune, ancien enseignant chercheur de l'École des Mines de Saint-Étienne, ont donné une conférence sur la Cyber-Sécurité

Rare earth elements and uranium in Minjingu phosphate fertilizer products: Plant food for thought,Resources, Conservation and Recycling

International audienceMinjingu phosphate ore is Tanzania's sole domestic supply of phosphorus (P). The ore contains medium to high concentrations of naturally occurring P2O5 (20–35 %) and relevant concentrations of uranium and rare earth elements (REEs) are also suspected to be present. Currently, neither uranium nor REEs are recovered. They either end up in mine tailings or are spread across agricultural soils with fertilizer products. This work provides a first systematic review of the uranium and REE concentrations that can be expected in the different layers of Minjingu phosphate ore, the way the ore is presently processed, as well as a discussion on alternative processing pathways with uranium/REE recovery. The study analyzed ten distinct Minjingu phosphate ore layers, four mine tailings, and five intermediate and final mineral fertilizer products from the Minjingu mine and processing plant located in northern Tanzania. The results confirm that the uranium concentrations and to a lesser degree, the REE concentrations are indeed elevated if compared to concentrations in other phosphate ores. The study does not identify a significant risk resulting from this. The development of techno-economic solutions for more comprehensive utilization of Minjingu ore is, however, strongly encouraged and suggestions on such processes are provided

Emergence des projets collaboratifs: Une analyse par les évènements en tant que dispositifs managériaux.

International audienceThe analysis of the emergence phase of collaborative projects remains underexplored in the literature, often focused on later stages. This study on the collaborative project Campus Numérique initiated by French Tech in the Alps in Grenoble identifies three phases characterized by an alternation between cooperation and coordination. By examining the role of events as managerial devices, this research highlights that events provide crucial support for cooperation and coordination actions. These events initially structure collective learning through a common language, then align and prioritize resources, ultimately reinforcing common and shared values.L’étude de la phase d’émergence des projets collaboratifs reste peu explorée dans la littérature, souvent axée sur les étapes ultérieures. Cette recherche sur le projet collaboratif Campus Numérique initié par la French Tech in the Alps à Grenoble identifie trois phases caractérisées par une alternance entre coopération et coordination. En examinant le rôle des évènements en tant que dispositifs managériaux, notre recherche met en évidence que les évènements fournissent un soutien crucial aux actions de coopération et de coordination. Ces évènements structurent d’abord un apprentissage collectif via un langage commun, puis alignent et hiérarchisent les ressources, pour enfin renforcer les valeurs communes et partagées

SHAPE: A temporal optimization model for residential buildings retrofit to discuss policy objectives

International audienceIn a context of massive renovation of residential buildings, stakeholders need decision-support models based on knowledge of the current building stock and accurate simulation of energy demand. This paper presents a new strategy for reducing energy consumption in the building sector, a key factor in combating climate change and promoting sustainability. We introduce an approach to (1) plan retrofits at community level, with a building resolution, for different years of an optimization period and (2) assist local authorities in selecting effective measures to improve the environmental performance of their building stock. The focus is on creating trajectory retrofit plans creation for a building stock with three main retrofit options: improving insulation, heating systems and hot water systems. We adapt a complex but linear approach, a type of problem-solving structure known as a multidimensional multiple-choice knapsack problem, which manages to handle a large number of possible retrofit combinations without becoming unwieldy. The planning process is streamlined as a single-objective optimization task that aims to reduce the total cost of retrofits by reducing their net present value.The efficiency of the model is demonstrated by simulating retrofit scenarios for 4,000 buildings in a French region to prove its ability to tackle large problems. France’s targets for decarbonizing the residential sector are taken into account, with a target of reducing GHG emissions by a factor of 10 and a building stock consuming 80kWhEP/m2/year. The results show that these plans are feasible, but that they will require 50% of all buildings to undergo major renovation with abatement costs of around €200/tGES. Our practical application to an actual community demonstrates the model’s ability to identify appropriate retrofitting measures and compile building data

Toughening and strengthening of visible light-cured hydroxyapatite thiol-ene resin composite intended as bone fixation using 2D textile

International audienceInfection and inflammation are two key features to consider to avoid septic or aseptic loosening of bone-implanted biomaterials. In this context, various approaches to fine-tune the biomaterial's properties have been studied in order to modulate the crosstalk between immune and skeletal cells. Cation-doping strategies for tuning of calcium phosphates properties has been evidenced as a promising way to control the biomaterial-induced inflammatory process, and thus improving their osteoimmunomodulatory properties. Copper(II) ions are recognized for their antibacterial potential, but the literature on their impact on particulate material-induced acute inflammation is scarce. We synthesized copper(II) ions-doped biphasic calcium phosphate (BCP), intended to exhibit osteoimmunomodulatory properties. We addressed in vitro, for the first time, the inflammatory response of human primary polymorphonuclear neutrophils (PMNs) to copper(II) ions-doped or undoped (BCP) powders, synthesized by an original and robust wet method, in the presence or absence of LPS as a costimulant to mimic an infectious environment. ELISA and zymography allowed us to evidence, in vitro, a specific increase in IL-8 and GRO-α secretion but not MIP-1β, TNF-α, or MMP-9, by PMNs. To assess in vivo relevance of these findings, we used a mouse air pouch model. Thanks to flow cytometry analysis, we highlighted an increased PMN recruitment with the copper(II) ions-doped samples compared to undoped samples. The immunomodulatory effect of copper(II) ions-doped BCP powders and the consequent induced moderate level of inflammation may promote bacterial clearance by PMNs in addition to the antimicrobial potential of the material. Copper(II) doping provides new insights into calcium phosphate (CaP)-based biomaterials for prosthesis coating or bone reconstruction by effectively modulating the inflammatory environment

Improved printability and electrical conductivity of carbon black polymer composite with a customized nozzle of material extrusion process

International audienceDue to the interactions between the fillers, the polymer and the die, the printing of filled polymer composites using the material extrusion process is challenging. Numerical computations have been carried out to investigate the fluid dynamics and heat transfer within the hot end of the material extrusion process. Firstly, a standard nozzle equipping the majority of 3D printers is considered. However, it is not possible to print an object on a commercial printer with a composite made of polylactic acid with 20wt% of carbon black due to clogging issues. This impossibility is supported by the application of the Q-criterion, which is an indicator of flow kinematics. As a result, a novel nozzle design is proposed. The printing of the same object on the same printer equipped with the new nozzle succeeds. The electrical properties of walls printed with both the standard and the new nozzles are evaluated. The conductivity of a wall printed with the new nozzle is 42% higher than that of a wall printed with the standard nozzle. Furthermore, complementary analysis using scanning electron microscopy shows that the porosity of the walls printed with the new nozzle is reduced which is a promising improvement

L’évolution du business model des startups par la digitalisation : quel lien avec leur croissance ?

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Design and engineering of value-driven Smart PSS for manufacturing companies: Design risk anticipation with sPS2Risk Framework

International audienceDigital servitization has emerged over the last years, at the convergence between digital- and service-oriented business strategies, leading manufacturing companies to transform their business models through the adoption of so-called Smart PSS (Smart Product-Service-Systems). As a contribution to the relatively recent scientific literature on Smart PSS design, this paper presents a framework for the design and engineering of Smart PSS offers, based on a value-driven approach. The added-value of the framework is notably to integrate (i) a smart PSS prototyping approach associated with (ii) a risk management process, all along the design process. When a manufacturing company has to shift from a ‘product-centric’ to a ‘Smart PSS’ business model, sPS2Risk Framework helps decision-makers anticipating and mitigating key innovation risks. The paper presents the generic framework and its experimentation for an industrial case study, in the heating appliance sector