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Towards the elimination of water in THz-TDS data
No full textInternational audienceOne of the most problematic points in THz-TDS is the absorption induced by water lines. This absorption complicates and biases the fitting algorithms. We propose here an approach to eliminate water from TDS data. The 1parameter model can eventually be used to quantify water present in different samples.</div
Gray Wolf Optimization Algorithm for Fuzzy Logic Driver Behavior Model
No full textInternational audienceIn this study, we propose a fuzzy decision system for human involvement in a driver-vehicle-environmentsystem, capturing takeover scenarios by different drivers. The driver’s behavior is influenced by environmentalfactors. Expert opinions, gathered through questionnaires, contribute to defining fuzzy rules in a desired modelthat consider the impact of parameters such as climate, road, and car conditions on driving capabilities. The fuzzymodel encompasses steering angle and speed control, accounting for time distances with surrounding cars, theirspeed and direction, and the car’s steering angle. To optimize the proposed model, reduce computing time, andalign it with the desired fuzzy model, the gray wolf algorithm is employed to tune the membership functions againsta fitness function error between the desired and the proposed model. Results from SCANeR Studio softwaredemonstrate the effectiveness of the proposed model in accurately representing the influence of driver profilecharacteristics
Evaluation of the Impact of Infusion Set Design on the Particulate Load Induced by Vancomycin–Piperacillin/Tazobactam Incompatibility
No full textInternational audienceIntroduction: Drug incompatibilities are among the most common medication errors in intensive care units. A precipitate can form and block the catheter or cause an adverse event in the patient. Intensive care units have implemented various strategies for limiting the occurrence of these incompatibilities, which have already been studied in vitro under standardized conditions. The objective of the present in vitro study was to continue these assessments by determining the impact of the infusion line geometry and the drugs' position in the infusion set-up on the prevention of vancomycin-piperacillin/tazobactam incompatibility.Methods: Infusion lines with a different common volume, a multilumen medical infusion device, a dilute vancomycin solution, and separate infusions of incompatible drugs were evaluated separately. The infusion line outlet was connected to a dynamic particle counter. Results: Reducing the common volume, using multilumen medical devices, or spacing out the two incompatible drugs on the infusion line did not prevent the occurrence of a significant particulate load. Only dilution of the vancomycin solution was associated with a significantly lower particulate load and the absence of drug incompatibility.Conclusions: Our results show that under specific conditions, it is possible to reduce particulate contamination considerably
Optimization of WLAM process Parameters for Metal Forming Tool Repair
No full textInternational audienceTool wear in metal forming leads to a drop in product quality and non-compliance with initial specifications. Tools exhibiting noticeable wear are typically replaced, incurring additional costs and environmental concerns. With the advent of the metallic additive manufacturing, there is now the possibility of repairing tools instead of outright replacement. This innovative approach can be applied in metal forming processes to locally add melted materials, effectively repairing forming tools. It is obviously crucial that the repaired tool possesses the same or better tribological properties than the initial tool, otherwise the benefit of repairing tool will be lost due to poor tribological properties.In this study, a wire laser additive manufacturing system, equipped with a six-beam direct diode laser head, is involved to repair worn surfaces of metal forming tool. The study focusses on the influence of process parameters on the behaviour of the weld bead and substrate. a particular attention is paid on the effect of the impact of energy density on the hardness, microstructure, dimensional stability, and the penetration of weld beads into the substrate.Preliminary results show that optimal morphological stability and homogeneity of the weld bead are achieved at an energy density greater than 100 J/mm3. The friction tests show a good response of the reloaded tool in terms of substrate/weld bead adhesion and friction coefficient. However, the friction coefficient remains high compared to the initial tool. And a large heat-affected zone (HAZ), with a martensitic structure, is generated under the weld bead. Future tests will focus on improving tribological properties and reducing HAZ hardness
Seawater corrosive engineering assisted in-situ room temperature synthesis of Ni/Co/Fe trimetallic composition to achieve polyester plastics upgrading and green hydrogen production
No full textInternational audienceUtilizing electrochemical processes for plastic waste upcycling into valuable chemicals represents an optimal approach for extracting value from waste resources. Herein, we developed a low-cost and large-scale approach based on seawater corrosion engineering to construct amorphous CoFeNi material on nickel foam (A-CoFeNi), which effectively converts ethylene glycol (EG) from waste polyethylene terephthalate (PET) hydrolysate into formate. The optimized A-CoFeNi only necessitated 1.25 and 1.38 V vs. RHE to achieve 10 and 100 mA cm−2, respectively, demonstrating excellent EG oxidation reaction performance. In addition, the application of an ultra-low Pt content coating on A-CoFeNi, resulting in the preparation of a Pt-CoFeNi cathode catalyst, exhibited remarkably low overpotentials of 44 and 122.1 mV, respectively, to acquire current densities of 10 and 100 mA cm−2 for HER in 1 M KOH seawater. In the co-electrolysis system, the Pt-CoFeNi // CoFeNi exhibited excellent Faradaic efficiencies for the simultaneous generation of formate (94.8 %) and H2 (∼100 %). The enhanced activity and stability of this system could be ascribed to CoFeNi trimetallic cooperation and strong electronic interactions. This research provides valuable insights into leveraging seawater corrosion technology for the large-scale synthesis of catalysts, achieving efficient seawater utilization and electro-reforming PET plastic waste into high-value chemicals
Tuning Deposition Conditions for VN Thin Films Electrodes for Microsupercapacitors: Influence of the Thickness
No full textInternational audienceVanadium nitride is a highly promising material for micro-pseudocapacitors when used as a bifunctional thin film, i.e. an electrode material and a current collector, owing to its remarkable electrical and electrochemical properties. However, the specific limitations associated with high-rate cycling remain unclear. In this study, we evaluate how the characteristic time associated with charge/discharge of vanadium nitride films is modified with the film thicknesses using electrochemical impedance spectroscopy and cyclic voltammetry measurements coupled to a semi-empirical model commonly utilized to assess the high-rate behaviour of battery electrodes. Both methodologies are in good agreement and revealed that rate capability of this bi-functional material is limited by the VN electrical conductivity. To confirm this finding, VN thin films were sputtered on platinum current collectors, leading to a six-fold reduction in the characteristic time associated with charge/discharge of the current collectors/electrode material. This underscores the importance of using current collectors even for highly conductive electrode materials
Topological bound modes in phononic lattices with nonlocal interactions
No full textInternational audienceTopological protection has opened new possibilities for unconventional wave guiding, object cloaking, improved energy transport, as well as surface, edge, or corner mode localization. In elasticity, these phenomena have largely been explored and exemplified through discrete models having nearest neighbor couplings. Interactions beyond the nearest neighbors in one-dimensional studies, on the other hand, have recently shown great potential for topological wave phenomena.In this work we investigate the topological modes of a two-dimensional mass–spring hexagonal lattice with connections between both nearest and third nearest neighboring masses. We show that non-nearest connections allow for (i) the formation of additional Dirac cones and (ii) a migration in their location in the reciprocal space as a function of the relative stiffness between nearest and third nearest neighbor connections. These additional Dirac cones are linked to a corresponding increase in the number of topological edge modes, which hybridize and result in bound modes at interfaces between lattices that are inverted copies of each other. Explicit expressions for the mode shapes and frequencies of these bound modes are derived and their topological origin is elucidated. We also demonstrate that by varying the relative stiffness between nearest and third nearest neighbor connections, bound modes lying in the band gap can be achieved. While in the case of only nearest neighbor connections the bound modes are at a fixed frequency in the pass band, varying the stiffness of a single nonlocal spring can shift their frequency and isolate them as desired within a band gap. Transient numerical simulations conducted on a finite lattice allow to quantify the confinement along the transverse direction as a wave propagates in a waveguide with sharp turns, reporting negligible backscattering. Finally, a possible realization of hexagonal unit cells with third nearest neighbor connections is proposed.The concepts here presented open novel avenues for topological wave guiding and confinement leveraging bound modes to design waveguides with superior energy localization potential
En procédure gracieuse aussi, les tuyaux sont ouverts (Civ. 2e, 4 avr. 2024, n° 22-10.677, P), D. actu. 24 avr. 2024
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