Portail HAL UHA (Université de Haute-Alsace)
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17715 research outputs found
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La notification du droit de se taire devant la commission des sanctions de l'AMF
No full textInternational audienc
Caractérisation avancée d’un élastomère par traction quasi-statique modulé
No full textInternational audiencePolymers exhibit complex mechanical behavior. Rubber or similar materials are known to display both viscoelasticity and nonlinear elasticity. However, quasi-static mechanical tests alone are insufficient for capturing the viscous component of their response. While Dynamic Mechanical Analysis (DMA) provides valuable insights, it is inadequate to characterize the material's behavior under large deformations fully. A hybrid approach combining a quasi-static tensile test with modulation is proposed to address these limitations. During these tests, deformation fields obtained via Digital Image Correlation (DIC) can be complemented by infrared thermography. The experimental setup is based on a modified DY22 universal testing machine. Tests were performed on a rubber band designed for sports applications. The mechanical results, including the load-elongation relationship and field measurements, reveal distinct differences between the quasi-static and modulated components. These differences are particularly evident in the evolution of the elastic modulus and Poisson's ratio as a function of elongation. The measurements provide detailed insights into the material's mechanical response at each loading stage. The results demonstrate that integrating modulated testing techniques with thermomechanical analysis allows for a more comprehensive characterization of materials for engineering applications
Optimizing the potential of KM3NeT in detecting core-collapse supernovae
No full textCore-collapse supernovae mark the end of life of massive stars. However, despite their importance in astrophysics, their underlying mechanisms remain unclear. Neutrinos that emerge from the dense core of the star offer a promising way to study supernova dynamics. A strategy is presented to improve the potential of the KM3NeT neutrino telescope to detect core-collapse supernovae in our Galaxy or the Large Magellanic Cloud by further exploiting the properties of its optical modules equipped with multiple photomultipliers. A supernova burst is expected to produce a sudden hit rate increase in the KM3NeT detectors. New observables have been defined for individual optical modules that exploit the geometry and time distribution of the detected hits, enabling a better discrimination between signal and background signatures. In addition, a thorough investigation of the related systematic uncertainties is presented for the first time. When implemented, this new methodology allowed KM3NeT to probe 46% more Galactic core-collapse supernova candidates than with the previous trigger strategy, reaching the dense Galactic bulge. It is now expected that, once completed, KM3NeT will achieve full Galactic sensitivity to core-collapse supernovae
Suppression législative de la condition de cohabitation des parents civilement responsables : la responsabilité parentale au milieu du gué
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Centralized Distance-based MPC Strategy for Local Formation Tracking of a Multi-Robot Fleet
No full textInternational audienceIn this paper, a centralized control strategy is proposed to perform the formation tracking (FT) of a multi-robot fleet, without using absolute position information. The core of the approach lies in the predictive regulation of inter-agent distances using model predictive control (MPC) to improve robustness against deformations. The proposed strategy allows the formations to be efficiently maintained around the moving leader, even in GPS-denied conditions. To evaluate the advantages of using a distance-based formalism for local formation tracking, the proposed strategy is then compared with another approach inspired by the literature, in which robots maintain positions with respect to the fleet centroid. Simulation results show the efficiency of the proposed MPC framework in maintaining a local formation around the leader and highlight the benefits of using the distance-based formalism in constrained settings. To conclude the study, further discussions are made about the specification of each formalism
New method for quantitative thermal gravimetric analysis per compound - method validation and application to adsorption
No full textInternational audienceWe summarise the numerical method used to process data from conventional thermogravimetric analyser/mass spectrometer coupling, giving the quantified desorption temperature distributions for each compound without requiring evolved gas calibration. The method was validated through experiments involving two compounds adsorbed onto hydrophilic zeolite preloaded with water, either from toluene solutions at varying initial concentrations in isooctane, or under dynamic gas-phase adsorption using 1,2-dichlorobenzene evaporated in a nitrogen flow. These experiments generated overlapping desorption peaks with distinct positions and shapes, representing challenging test conditions. Computed desorbed quantities were compared with adsorbed quantities from the depletion method for toluene at low and high initial concentrations. The sum of the negative-derivative thermogravimetric curves computed per compound closely matched the experimental thermogravimetry curve, confirming amplitude linearity for both thermogravimetry and mass spectrometry responses, and the independent gas mixture transfer. This validates the application of the superposition principle in the model. The close agreement between the adsorbed and computed desorbed quantities for toluene, in the presence of water and isooctane, confirmed the reliability of the numerical approach. Desorbed quantities as low as 2.2 % of the total were accurately resolved. Particular attention was given to sample preparation, especially in relation to hydrophilic materials, leading to the validation of a robust drying protocol. Finally, for the study of competitive adsorption of water and 1,2-dichlorobenzene onto FAU-Nd-Na zeolite, the method showed that 1,2dichlorobenzene inhibits water adsorption on SIII sites and that increasing neodymium exchange shifts the water desorption temperature distribution towards lower temperatures
Un essayeur incompétent. L'affaire Reyslander, Sainte-Marie-aux-Mines, 1571-1572
No full textInternational audienceDans les exploitations minières modernes, l’essai des minerais a joué un rôle majeur dans les relations entre mines et fonderies. Il était exigé de l’officier essayeur des qualités morales et techniques devant assurer des résultats représentatifs et reproductibles. Les plaintes de concessionnaires et l’embarras de l’administration minière mettent en évidence l’exigence du savoir-faire requis et la rareté des personnes qualifiées dans le massif vosgien du second XVIe siècle
When light betrays colour: the photodegradation of alizarin, a historical dye, in basic media
No full textInternational audienceArchaeological and historical evidence indicates that natural dyes have been employed by human societies for millennia to achieve colouration in various materials. And light reveals this world of colours by painting everything it touches. However, there is much evidence that natural dyes photodegrade when exposed to light, fading cultural heritage work. Upon photon absorption, a molecule reaches an excited state, which promotes photochemical reactions leading to the formation of new compounds and thus the photodegradation. Understanding the underlying mechanisms of these processes helps elaborate effective strategies to mitigate them. These problematics have long been relevant across various fields. There have been many studies about the photodegradation of dyes, and this continues until today. Our study focuses on alizarin, a historical natural dye that can be extracted from madder roots. It has been used in many fields, textiles, paintings, since antiquity. A distinctive aspect of our study is the investigation of alizarin's less-studied basic (di-deprotonated) form, using a solution model under controlled conditions. By using techniques such as EPR and HPLC-UV-MS, we identified radical oxygen intermediates and degradation products while evaluating the influence of pH, solvent and light wavelength. These findings have important implications for preserving alizarin-based artworks, improving industrial dyeing practices, and informing environmental efforts like wastewater treatment and shedding light on computational modelling as a crucial research field in these topics. Overall, the study deepens our understanding of anthraquinone dye degradation and promotes the sustainable use of natural dyes