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Multisensory objects’ role on creativity
No full textInternational audienceIn this research, we investigated the role of multisensorial manipulation on creativity, and the influence ofinspirational objects on creative outcomes. Object manipulation may support embodied cognition during agenerative creative phase (emergence of motor, spatial, emotional ideas, etc.) then exploratory phase (creativefixation, development of a functional creation, etc.). Our protocol involved 136 engineering students divided into34 groups which were provided with inspirational cubes illustrating manufacturing inventive principles or basicvolumes from the Creative Mental Synthesis Task. They could manipulate these objects either in a visuo-hapticcondition, or in a visuo-imaginative condition. Our results highlighted a main effect of manipulation, showingthat visual-haptic condition led to higher creativity than visual-imaginative condition. We also observed severaleffects in favor of inspirational cubes with regard to basic volumes: significantly higher creativity, more sub-jective and inter-subjective facilitation behaviors, more cognitive and emotional operations. Participants alsoshowed at an individual level a better mobilization of the multisensorial senses. Creative thinking may bestimulated when an active manipulation phase is set up before the creative production. This could contribute toimproving practice for engineers, particularly for using additive manufacturing and/or during their training atschoo
From pine cones to 4D materials: predicting humidity-driven sequential shape morphing
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Learning how to use a Decision Support System: a simulation of Human-AI interaction frames
No full textMany studies address human-AI interaction by focusing on the direct behavioral effects of AI on humans, often assuming a static view of human decision-making. However, a defining feature of human intelligence is its capacity for continuous learning. Experiments designed to study this learning process are challenging to implement due to their duration and the presence of numerous uncontrollable variables. To overcome these limitations, it is essential to explore potential solutions through numerical simulations. This study proposes a simulation paradigm, and use it to explore new frames (trust quota and mentalisation) for human-automation teaming. We compare them with reference approaches (human alone and AI as an advisor), simulating the learning phenomenon using artificial neural networks. Our findings suggest that trust quotas can boost human-performances, but that only the effort to develop mental models of AI may foster a resilience to the loss of AI advice
Development of Flexible Simulation Tool for Analysis of Microgrid Systems
No full textInternational audienc
Tank Testing of a Windfoil Hydrofoil with Free Surface Effects
No full textInternational audienceAbstract Hydrofoils used on many water crafts and boats, operate in close proximity to the free surface. While the behavior of wings in a single-fluid medium is well known, the effects of the free surface on hydrofoils are not precisely known. The high computational cost of CFD simulations with the air-water interface makes them difficult to be used to build a full hydrodynamic surrogate model with many input parameters, as needed for a Velocity Prediction Program (VPP). For a small hydrofoil, it is possible to test the full-scale foil in a towing tank and measure the hydrodynamic forces. This work presents a test campaign of the main lifting wing of the Olympic Class windfoil (IQFoil) hydrofoil in the towing tank of Centrale Nantes. The measurements carried out in different configurations of immersion, heel and trim, allow for exploring the operation of the hydrofoil and the impact of the proximity of the free surface on its performances. It is shown that the lift force and slope with angle of attack are reduced when approaching the free surface and that the variations of drag are dominated by the induced drag. When the wing pierces the free surface, ventilation may occur resulting in a sharp drop in lift. These experimental results can be used as a validation benchmark for numerical simulations and are useful to build the hydrodynamic force model intended to supply a VPP. Keywords hydrofoil; windfoil; IQFoil; free surface; towing tank; VP
Influence of additive manufacturing process parameters on Ti6Al4V surface properties and performances
No full textInternational audienceThis study investigates the effect of additive manufacturing process parameters on the surface characteristics and performances of titanium Ti6Al4V, used for orthopedic implants. Parts were manufactured by selective laser melting, using a variety of volumetric energy densities, ranging from 58 to 152 J/mm 3 . Through a rigorous optimization of process parameters coupled with optical examinations of porosity distribution and morphology, a volumetric energy density of 58 J/mm 3 was identified as an optimal manufacturing condition that resulted in extremely high densities of 99.8% in Ti6Al4V titanium alloy. X-ray diffraction measurements revealed the development of anisotropic residual stress states, characterized by elevated tensile stresses oriented along the build direction. Phase analysis results indicate a predominant martensitic acicular α′ structure, resulting from the rapid heating and cooling kinetics intrinsic to additive manufacturing, with a minor residual prior-β phase. Optical examinations reveal a microstructural transition from equiaxed prior-β grains to a columnar structure correlated with an increase in scanning speed (decrease in volume energy density). Corrosion tests were performed in Ringer's solution at 37 °C to simulate physiological conditions. It has been established that the presence of elongated pores combined with high tensile residual stresses can significantly compromise the corrosion resistance of additively manufactured parts. Minimizing porosity, through optimized SLM process parameters, significantly improved corrosion resistance. This resulted in a continuous and dense passive film, reducing the corrosion rate by 72%, from 22 to 6 µm/year. These findings enable prosthesis manufacturers to enhance additively manufactured implant performances, extending their longevity
Speed control of a sensorless seven-phase Surface-mounted PM machines
No full textInternational audienceThis paper deals with the speed control of a position sensorless seven-phase Surface-mounted PM machine. A vectorial ccontrol is achieved using the first, the third and the fifth harmonic rotating dq-planes, the latter being used to sense the position in normal mode. In order to extend the low speed range, the control strategy and the plane used to estimate the position are modified at low speed. This approach is validated by time-step simulations. If the speed is large enough, experimental tests confirm the effectiveness of the speed control in normal mode when the position is sensed with the fifth harmonic. At lower speed, experiments show the possibility of using the third harmonic
316L Stainless-Steel Carburizing Close to Eutectic Transformation Using the Spark Plasma Sintering Process.
No full textInternational audienceThis work focuses on the 316L austenitic stainless-steel case-hardening microstructure, after the SPS process near the solid/liquid state transition temperature. This process, faster than conventional carburizing techniques, is equivalent to weld cladding, allowing the achievement of high surface carbon contents with large-size carbide grains in the case of partial melting. Three distinct zones were formed: internal carburizing, carburizing with melting, and carburizing with melting and chromium depletion; all three composed of mixed carbides (CrFe)C distributed in an austenitic matrix. The internal carburizing layer growths following a parabolic kinetic law with k ≈ 10 cm/s, while the advancement of the melting front is very fast and follows a linear law with k = 1.0 x 10 cm/s at 1100 °C. The Cr-depleted fusion zone microstructure is similar to a composite material with a metallic matrix, which includes graphite particles, Mo-rich intermetallic phases, and core-shell eutectic carbides. The partial melting zone without Cr depletion shows the formation of a dense carbide layer with diameters exceeding 10 µm, constituting 60% of the volume, and achieving a hardness of 850 HV. Its wear rate is about 100 times lower than the 316L steel, indicating a significant improvement in the alloy's wear behavior
Information Fusion for Real-Time Occupancy Estimation Using CO2 Dynamics and PIR Sensors in Smart Building
No full textInternational audienceReal-time estimation of occupants number in buildings is crucial for managing and reducing the energy consumption of HVAC systems. Currently, estimation is mainly performed using black box models. These models require large datasets with ground truth values, which are often unavailable. Due to the difficulty to dynamically modeling occupancy change, an approach combining gray box models with information fusion techniques should overcome this issue. This study proposes a fusion of two complementary estimators. First estimator, is based on a physical model of CO2 dynamics, which has proven effective for occupancy estimation, but suffers from a certain time lag. Second estimator, is based on PIR sensor, known for their sensitivity to occupancy dynamics, but less effective when occupancy becomes static. Two widely used fusion algorithm approach has been compared: Kalman filter and Dempster-Shafer theory. In addition, four black box models were developed using the same approach in order to compare techniques. Information fusion algorithms produce similar results and provide a better representation of room occupancy than basic estimators or black box models. With a global accuracy of 89% and an MAE of 0.14 occupant
Design of Multiphase Compositionally Complex Alloys for Enhanced Hardness at Elevated Temperatures and Machinability: Comparative Study with Inconel 718
No full textInternational audienceInconel 718 alloy is used for high‐temperature industrial applications in its optimized multiphase metallurgical state. Nevertheless, the machining of Inconel 718 alloy becomes problematic and challenging. One alternative consists of developing a new material design strategy based on the metallurgy of high‐entropy alloys (HEAs). These alloys have become a hotspot in the field of innovative high‐temperature metallurgy toward the improvement of the alloy's manufacturability and thermomechanical properties. This study aims at designing, elaborating, and characterizing a new class of alloys with increased entropy, referred to as: “Inco‐like.” The mechanical responses of the alloys, in terms of hardness, have been analyzed using an indentation test at a wide range of temperatures. The dry machinability of the developed alloys has been performed and compared with that characterizing the Inconel 718 in terms of several machining features. Finally, the phases of the studied alloys have been analyzed using metallurgical investigations. The experimental findings and comparisons underscore the advantages of the high‐entropy strategy in terms of tool wear reduction and cutting tool durability. The results demonstrate that the Inco‐like HEA retains a significantly higher hardness of 291 Hv at 800 °C, compared to 160 Hv for Inconel 718 at the same temperature