An innovative setup to study the breakage of SiO2 agglomerates under shear stress

International audienceGranular materials are involved in many industrial processes such as mixing, compaction, etc. When the granular material is in the form of agglomerates, i.e. an assembly of aggregates, particle fragmentation might occur under shear stress. This can either be a benefit for the process and should be controlled, or an issue which must be avoided. This paper focuses on the study of agglomerate breakage under shear stress, presenting a new experimental set-up designed for industrial contexts. The stress range selected lead to two distinct regimes: at low stresses, agglomerates break into individualized fragments, while high stresses fines agglomeration leads to the formation of flakes. These observations contribute to quantify the breakage stress of initial agglomerates, showing agreement with findings in the existing literature

Opportunities from energy-loss near-edge fine structure analysis to track chemical and structural damage in zircon

International 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

Shear mechanical properties measurements at the surface scale: Enhanced performances of the micro-shear compression specimen

International audienceAn intensive study combining experimental tests and numerical simulations was carried out to improve the understanding of the micro-shear test using the Micro-shear Compression Specimen (MCS). The results demonstrated good data reliability in the elastic regime up to the yield stress. However, the study also revealed that friction between the flat punch and the MCS significantly affects the plastic regime, and must therefore be accounted for to accurately extract shear mechanical properties. To overcome this limitation, two alternative methods were developed. The first one consists in compressing a new type of micro-shear compression specimen, featuring two perpendicular gauges forming a cross geometry (X-MCS). The second consists of applying multicycle loading to the conventional MCS. Both approaches successfully eliminated friction dependence in the plastic regime, in contrast to the classical method. Finally, the X-MCS geometry was applied to very high strain rate testing on fused silica. Thanks to the small gauge height of the X-MCS, it was possible to measure shear mechanical properties at a strain rate of 104 s−1, which was not achieved using conventional micropillar compression with our micromechanical setup. These methods provide a new pathway for extracting shear mechanical properties, which are critical in the field of tribology, where surfaces are subjected to intense shear deformation

DEM with Coarse Graining: Should Same Size Parcel receive more attention? Bridging the gap in the case of size-driven segregation

International audiencehe Discrete Element Method (DEM) has gained significant popularity as a technique for simulating granular flows. However, its high computational cost has remained a primary limitation for decades. This limitation hinders its application in simulating realistic large-scale industrial scenarios. The Coarse Graining (CG) method addresses this issue by substituting physical particles with up-scaled particles, commonly referred to as parcels. Among CG techniques, the Same Size Parcel (SSP) approach is considered the most efficient, as it achieves the greatest reduction of constituents in poly-disperse media. Nevertheless, SSP is unable to simulate size-driven phenomena, such as segregation, which significantly restricts its applicability to systems with size heterogeneity. In this context, the present article introduces a novel local model that captures size-driven segregation during Coarse Grained — Same Size Parcel (CG-SSP) simulations when in dense regime. Preliminary results from flowing chute modeling indicate highly promising outcomes, suggesting a potential advancement towards the rapid simulation of poly-disperse, large-scale particle flows

Evaluation of global biotic resource consumption against absolute boundaries

International audienceHuman activities rely on biotic natural resources to provide products and services necessary to meet human needs. This instrumental value is captured in life-cycle assessment through the “Natural resources” Area of Protection. Although several absolute boundaries have been proposed to safeguard biotic resources, it remains unclear whether these resources are currently used at a sustainable rate. This study addresses this question by evaluating global biotic resource consumption from 1995 to 2011 against suggested biotic resource boundaries, relying on Exiobase projections to assess the evolution beyond 2011. The assessment couples absolute boundaries with life-cycle impact assessment (LCIA) methods, enabling evaluation using consistent LCIA metrics. Five absolute boundaries and four LCIA methods were adapted to the Exiobase multiregional input-output model. Results show that most of existing boundaries are already transgressed, regardless of whether mass-based or LCIA-based control variables are applied. The wide range and normative nature of existing boundaries emphasize the need for harmonized, science-based boundaries to ensure the sustainable use of biotic resources

Investigating the role of molecular coating in human corneal endothelial cell primary culture using artificial intelligence-driven image analysis

Gauthier Travers and Louise Coulomb contributed equally to this work - Gauthier Travers et Louise Coulomb ont contribué à parts égales à ce travailInternational audienceThe monolayer of approximately 300,000 human corneal endothelial cells (hCECs) on the posteriorsurface of the cornea is essential to maintain transparency but is non-self-regenerative. Cornealblindness can currently only be treated by corneal transplantation, hindered by a global donorshortage, highlighting the need for developing tissue and/or cell therapy. The mass production ofthese advanced therapy medicinal products requires obtaining high-yield, high-quality endothelial cellcultures characterized by hexagonal shape, low size variability, and high endothelial cell density (ECD).Among the usual critical quality attributes which combine the expression of differentiation markers,ECD and cell morphological parameters, the latter are not optimally measured in vitro by conventionalimage analysis which poorly recognizes adherent cultured cells. We developed a high-performanceautomated segmentation using Cellpose algorithm and an original analysis method, improving thecalculation of classical morphological parameters (coefficient of variation of cell area and hexagonality)and introducing new parameters specific to hCECs culture in vitro. Considering the importance ofthe extracellular matrix in vivo, and the panel of molecules available for coating cell culture plastics,we used these new tools to perform a comprehensive comparison of 13 molecules (laminins andcollagens). We demonstrated their ability to discriminate subtle differences between cultures

High temperature chromium coating cracking investigation during tensile tests monitored by acoustic emission

International audienceThe present study focuses on in-situ measurements of crack initiation and propagation in first-generation PVD-HiPIMS chromium coatings on M5Framatome11M5Framatome is a trademark or a registered trademark of Framatome or its affiliates in the USA or other countries. cladding substrates using an acoustic emission (AE) device and a tensile test machine. A key novelty of this work is the implementation of a temperature-controlled cracking monitoring system adapted to the cladding geometry under tensile loading. Post-mortem examinations (after different interrupted tensile tests) provide an evaluation of the in-situ method for determining the crack initiation threshold and crack density evolution. The critical strain to crack initiation increases exponentially from 0.4 % at room temperature to 3 % at 350 °C. Above 410 °C, the coating no longer exhibits brittle cracking until reaching high macroscopic imposed strain (up to 30-50 %). Additionally, the crack density decreases more or less linearly with the increasing testing temperature. At higher temperatures, the coating becomes highly ductile, consistently with the increased plasticity of pure chromium. SEM observations of the coating cross-section confirm that cracks do not propagate beyond the coating and that no delamination occurs. Thus, after rapidly reaching crack density saturation, the residual uncracked chromium coating exhibits significant plasticity and widening of the existing Cr cracks while providing slight mechanical reinforcement to the Zr-based cladding up to at least 400 °C

Facilitating Agile Transformation Through Business Process Standardisation – A Case Study

International audienceEnterprises across various sectors are adopting agile transformation as a strategic response to an increasingly dynamic business environment. However, this shift is often hindered by misconceptions, a lack of guidance, and growing process complexity. This paper aims to provide practical guidance for managing agile transformation projects by examining a scale-up initiative within a vocational training programme involving multiple teams. Drawing on Business Process Standardisation (BPS) and the Iterative Agility Improvement Framework (IAIF), the study demonstrates how structured approaches can streamline processes and support programme expansion. Specifically, the case study illustrates how IAIF can guide agile transformation efforts, highlights the role of process standardisation in aligning team perspectives and fostering collaboration, and underscores the importance of process modularisation in enhancing agility and performance. The findings offer valuable insights for practitioners seeking to operationalise agile transformation, particularly in contexts where collaboration is critical

Perspectives on Regulation Adaptation in Multi-Agent Systems: from Agent to Organization Centric and Beyond

International audienceIn Multi-Agent Systems (MAS), the regulation of agents aims to define a balance between the control of the system and the agents' autonomy. The ability of a MAS to adapt its regulations at run-time is an important feature that enables it to be flexible to changing situations. There is no unique approach to designing such ability. In this paper, we discuss the different options along the multi-agent oriented programming dimensions, i.e., agent, environment, interaction, and organization. We show that regulation adaptation can be managed within a single dimension or distributed in multiple dimensions. We use a case study in the manufacturing system domain to motivate the regulation adaptation in each of these dimensions

Stochastic image generator for industrial bin-picking simulation

International audienceIn modern industrial automation, bin-picking remains a challenging task due to the unpredictable and chaotic distribution of parts on a surface. Reliable robotic grasping depends on effective separation and alignment of components, often requiring complex tuning and setup. Expertise Vision, a company based in France, has developed a vibrating system called PVR (Plateau Vibrant Rotatif, or Rotating Vibrating Plate), which facilitates part separation and radial alignment through carefully tuned vibration recipes