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How to Better Integrate Game Theory into Technological Forecasting: Some Challenges to Tackle
No full textInternational audienceThe ability to make strategic decisions and anticipate competitors’ actions is crucial for companies to remain competitive in rapidly evolving industries. Technology roadmapping provides a comprehensive approach to assess technologies, their application, and developmental timelines. However, constructing an accurate roadmap poses challenges due to the dynamic market environment and the subjective nature of project evaluation. This paper studies the use of game theory for technology roadmapping to enhance strategic decision-making. Challenges in applying game theory, including perfect information assumptions, rational actor assumptions, utility functions modeling and successive decision-making, are examined. The necessity to bring application domain knowledge into the equation suggests an approach to bring knowledge representation techniques into game theory and see how such approaches can enhance decision-making. Metagame analysis and its branches are examined
Characterization of a solid recovered fuel for prediction of its thermal degradation
No full textInternational audienceThe objective is to characterize one solid recovered fuel (SRF) and to determine a mixture of model components to represent each of its fractions, both in terms of elemental composition and thermal degradation kinetics. The SRF was first sorted into fractions: hard plastic (21%, mass fraction), soft plastic (12%), wood (15%), paper and cardboard (13%), textile (11%), elastomer (6%), foam (4%), expanded polystyrene (PS, 3%), inert (6%) and fine particles (9%). The SRF fractions and selected model components were characterized in detail via thermogravimetric analysis (TGA), Fourier transformed infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDX). The results confirmed the relevance or presence of a list of model components for each fraction. In the second step, the mass fractions of the model components in the mixtures were calculated for each SRF fraction, with a mathematical optimization method based only on the elemental analysis results. These mixtures succeeded in representing the compositions of the fractions, both for organic and inorganic elements. The hard plastic fraction mainly contains polyethylene (PE) and polypropylene (PP) at 38.6% each, as do PS (5.0%) and polyvinylchloride (PVC, 10.9%). The soft plastic fraction is well represented by PE. The textile fraction is complex and includes cotton (15.0%), polyethylene terephthalate (PET, 40.5%), PP (20.9%), and acrylic (5.2%). The fine particle fraction is rich in pollutants: soil (29.8%), plaster (20.3%), and glass wool (5.0%). The consideration of these fine particles in the SRF composition is thus crucial for determining the sources of inorganic elements. © Zhejiang University Press 2025
Utilisation des réseaux sociaux pour faire face aux catastrophes naturelles - Comprendre les pratiques et les besoins
No full textThis document presents the main results of a questionnaire survey carried out as part of the RéSoCIO research project, with the aim of improving understanding of the needs of crisis management practitioners in terms of monitoring social networks in the event of fast-kinetic natural disasters.Ce document présente les principaux résultats d’une enquête par questionnaire réalisée dans le cadre du projet de recherche RéSoCIO, dans le but d’améliorer la compréhension des besoins des praticiens de la gestion de crise en matière de veille sur les réseaux sociaux en cas de de survenue de catastrophes naturelles à cinétique rapide
review
No full textInternational audienceTitanium and its alloys are widely used in the aeronautic field for their unique chemical and mechanical properties. However, this sector generates high amounts of waste, in the form of chips and scraps, when machining high-precision parts. These high-quality chips and scraps have begun to be recycled at an industrial scale, but the processes used are based on remelting technologies, which have high energy and consumable consumption. Moreover, these processes produce ingots that are not suitable for additive manufacturing purposes. The interest in alternative methods for the production of aeronautic-quality feedstock materials that can be used in additive manufacturing is increasing for complex geometries. The aim of this paper is to review the treatments and processes that can be used to recycle titanium-based chips and scraps into valuable additive manufacturing feedstock materials, with their advantages and shortcomings. Energy and consumable consumption are also given when available. Updated titanium production data are provided. The pre-treatments of titanium chips and scraps arealso discussed, as titanium is highly sensitive to oxidation, which remains a serious industrial issue. From this state-of-the-art review of titanium chip and scrap recycling, the identified promising technologies are continuous rotary extrusion (CRE) for wire production, and ball milling (BM) for powder production
Digital image computation of sooting flames by monte carlo method
No full textInternational audienceThis article sets out a collaborative operation of seven French research teams to compare the numerical simulation methods currently developed by each of them for coupled conductionradiation heat transfer resolution in heterogeneous semi-transparent media. The different deterministic and stochastic methodologies are succinctly presented, emphasizing the distinctiveness of each simulation strategy. The teams work on a common configuration encompassing shared thermal model, thermophysical parameters, boundary conditions and mesh description files. The results produced, i.e. the radiative, conductive and total net heat flux profiles and the temperature profiles, are analyzed and discussed. This study highlights the strengths and limitations of each method regarding the chosen configuration, with each offering a distinct perspective that complements the others. An overview of current strategies for addressing thermal coupling in heterogeneous media is offered, emphasizing that the selection of a method should align with the initial physical inquiry
Quantifying the impact of oxidation on the mechanical properties of Alloy 718 using local mechanical testing techniques
No full textInternational audienceDespite excellent oxidative properties of the Alloy 718 Ni-based superalloy, long-term exposure to oxidative environments in service creates a chemical gradient in the sub-surface affected by oxidation. Its characterization is key to assessing the evolving mechanical behavior of such affected materials. The present study focuses on the γ'-γ” precipitation depletion induced by the chemical gradient and benchmarks micro-mechanical testing techniques to assess local mechanical properties. Local techniques such as nanoindentation and micro-pillar compression were used to measure both elastic and plastic properties of a pre-oxidized Alloy 718 Ni-based superalloy, having a chemical gradient. These results were compared to a global approach by tensile testing and high-resolution digital image correlation (HR-DIC) on model materials corresponding to regions of the chemical gradient: the solid-solution and the precipitation hardened Alloy 718. The plastic behavior was investigated in terms of macroscopic yield strength and slip activity. Results obtained by the local and global techniques were found to be different but complementary. The relevance of the association of multiple micro-mechanical tests and sample preparation techniques to probe chemical gradients is discussed and technique advantages and drawbacks are exposed based on the single crystalline or polycrystalline nature of the micro-mechanical testing
Towards the 30 by 30 Kunming-Montreal global biodiversity framework target : optimising graph connectivity in constraint-based spatial planning
No full textIJCAI : International Joint Conference on Artificial Intelligence AI and Social Good, Montréal, CAN, 16-/08/2025 - 22/08/2025International audienceThe Kunming-Montreal Global Biodiversity Framework aims to protect 30% of terrestrial, inland water, marine, and coastal ecosystems worldwide, and ensuring that at least 30% of these areas are under effective restoration by 2030. Maintaining and restoring ecological connectivity between natural habitats and protected areas is a key feature of this target. Achieving it will require effective and inclusive spatial planning supported by appropriate decision-support tools. Most spatial planning models address budget as an objective and connectivity as a constraint, formulating problems with Steiner trees. In many real-world cases, such as landscape-scale restoration planning, this formulation is inappropriate when environmental managers seek to optimise connectivity under a budget constraint. This problem was previously addressed with Constraint Programming (CP) and graph variables, but the current approach is severely limited in terms of spatial resolution. In this article, we formalise this problem as the budget-constrained graph connectivity optimisation problem. Based on a real case study: the restoration of forest connectivity in New Caledonia, we illustrate why ``naive' CP approaches are inefficient. In response, we provide a preprocessing method based on Hanan grids which preserves the existence of at least one optimal solution. Finally, we assess the efficiency of our approach in the New Caledonian case study
Structural characterization of lead-doped hydroxyapatite synthesized by incipient wet impregnation and ion exchange techniques
No full textInternational audienceThe contamination of water and soil with heavy metals such as lead is a major global problem. Heavy metals affect the physiological functions of living organisms, cause cancer, and damage the immune system. Hydroxyapatite (Ca10(PO4)6(OH)2) is one of the most effective materials for the removal of heavy metals from contaminated water and soil. This study focuses on the structural characterization of lead-doped hydroxyapatite synthesized using two different methods: incipient wetness impregnation (IWI) and ion exchange under varying concentrations of Pb(II). Characterization methods such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), and thermogravimetric analysis (TGA) were used to understand the incorporation and/or the deposition of lead on the surface of calcined or uncalcined lead-doped hydroxyapatite. The XRD spectra show that for powders doped with more than 0.6% Pb, characteristic peaks of PbO and Pb(NO3)2 appear, respectively, with the calcined and uncalcined powders prepared by the IWI method. XRD characterization showed the formation of PbHPO4 and PbHAP for samples synthesized by ion exchange. These observations were approved by the results of the FTIR, SEM, and TGA analysis. TGA analysis of samples synthesized by IWI method showed the phenomena of dehydration of PbHPO4, decomposition of lead nitrate, and formation of [PbxCa5−X (PO4)3OH]. SEM micrographs show a crystal in quadratic form characteristic of the litharge (PbO). The crystal appears elongated, with a size close to 8–10 μm in length and a few hundred nanometers in width. Thermal analysis of samples synthesized by ion exchange showed possible dehydration of PbHPO4 and decomposition of lead nitrate. The results of this study confirm that hydroxyapatite doped with Pb(II) ions by dry impregnation or ion exchange constitutes an alternative for the decontamination of water and soil polluted by heavy metals
Airplane panels inspection via 3D point cloud segmentation on low-volume training dataset
No full textInternational audienceThis paper presents an approach for inspecting airplane fuselage panels using deep learning techniques, specifically segmentation models applied to 3D point clouds. A common challenge in deep learning applications is the limited availability of annotated training data — a problem particularly pronounced in industrial settings due to the high cost, time-consuming nature of data collection, and confidentiality concerns. Focusing on the detection and classification of rivets in the point cloud, our method aims to optimize the identification of potential defects, such as missing rivets or damaged rivets, even with minimal training data. Additionally, we evaluate the impact of different scanners and scanning resolution
Experimental study and modeling of the microstructural effects on the mechanical behavior of Ti-6Al-4V titanium alloy
No full textInternational audienceThis work is devoted to studying the coupled effect of grain size and crystallographic texture on the mechanical behavior at room temperature of Ti-6Al-4V alloy with an equiaxed microstructure. To this end, experimental data was collected on a broad range of mechanical solicitation conditions through monotonic and cyclic tests, followed by macroscopic elasto-viscoplastic modeling.The experimental results show that the mechanical behavior of Ti-6Al-4V is mainly influenced by both the grain size and the crystallographic texture. The microstructure with the finest grain size exhibits the highest flow stress. The weaklytextured alloy presents the highest ductility. Moreover, all the Ti-6Al-4V microstructures present cyclic softening behavior. In addition, at room temperature, no microstructure was found to exhibit significant strain rate sensitivity. The results also show that the grain size affects the yield strength of the Ti-6Al-4V alloy, as well as its ductility and its kinematic hardening.The proposed model formulation accurately predicts the effect of the microstructural features of the Ti-6Al-4V alloy. Isotropic and kinematic hardening laws are modified by introducing the grain size effects via the Hall-Petch relationship