"Le vilain qui vit un autre home od sa feme" de Marie de France - Édition et notes d'après le manuscrit York, Minster Library, XVI s. K-12 Pt. I

Édition et notes du "Vilain qui vit un autre home od sa feme" de Marie de France d'après le manuscrit York, Minster Library, XVI s. K-12 Pt.

Development of discontinuous Galerkin methods for hyperbolic systems that preserve a curl or a divergence constraint: the case of linear systems

Some hyperbolic systems are known to include implicit preservation of differential constraints: these are for example the time conservation of the curl or the divergence of a vector that appear as an implicit constraint. In this article, we show that this kind of constraint can be easily conserved at the discrete level with the classical discontinuous Galerkin method, provided the right approximation space is used for the vectorial space, and under some mild assumption on the numerical flux. For this, we recall a discrete de-Rham framework in which discontinuous approximation spaces for vectors fits. The discrete adjoint divergence and curl are proven to be exactly preserved by the discontinuous Galerkin method under a small assumption on the numerical flux. Numerical tests are performed on the wave system, the two dimensional Maxwell system and the induction equation, and confirm that the differential constraints are preserved at machine precision while keeping the high order of accuracy

Approximate Adsorption Performance Indicator in Evaluating Sustainable Bamboo-Derived Adsorbents for Biogas Upgrading

International audiencePurifying biogas by removing contaminants and carbon dioxide (CO2) to produce biomethane enhances its energy content, making it suitable as fuel and for injection into natural gas grids. Bamboo-derived adsorbents Bamboo-500 (pyrolyzed at 500 ∘C), Bamboo-700 (pyrolyzed at 700 ∘C), and Bamboo-A-900 (activated with CO2 at 900 ∘C) were synthesized and characterized to evaluate their performance for CO2 and CH4 adsorption. Increasing pyrolysis temperature from 500 ∘C to 700 ∘C and further CO2 activation at 900 ∘C enhanced adsorption capacities of CO2 and CH4 due to improved surface area and micropore structure. In this study, the novel Approximate Adsorption Performance Indicator (AAPI) approach is introduced, offering an efficient method for evaluating adsorbent performance, particularly in biogas upgrading. AAPI results suggest Bamboo-500 is suitable for biogas upgrading at very low pressures (<0.12 MPa) with low regeneration energy and acceptable CO2 capacity (1.9 ± 0.2 mol kg−1). However, Bamboo-A-900 excelled at medium and high pressures by its highest CO2 adsorption capacity (8.0 ± 0.3 mol kg−1) promoted by the high surface area (1220 m2g−1) and calcium oxide presence. Finally, Bamboo-A-900 shows promise for enhancing CO2 adsorption and biogas upgrading. Bamboo-derived adsorbents offer a sustainable solution for biogas upgrading, supporting Sustainable Development Goals by promoting clean energy transitions

"Le vilain et le folet" de Marie de France - Édition et notes d'après le manuscrit York, Minster Library, XVI s. K-12 Pt. I

Édition et notes du "Vilain et le folet" de Marie de France d'après le ms. York, Minster Library, XVI s. K-12 Pt.

Sire Hain et dame Anieuse - Édition, traduction et notes d'après le manuscrit BnF fr. 837

Édition, traduction et notes de Sire Hain et dame Anieuse d'après le manuscrit BnF fr. 83

Martin Hapart - Édition, traduction et notes d'après le manuscrit BnF fr. 12483

Édition, traduction et notes de Martin Hapart d'après le manuscrit BnF fr. 1248

Influence of Alkaline Treatment and Fiber Morphology on the Mechanical, Physical, and Thermal Properties of Polypropylene and Polylactic Acid Biocomposites Reinforced with Kenaf, Bagasse, Hemp Fibers and Softwood

International audienceThis novel study explores a comprehensive approach, combining fiber and matrix structure–property relationships. By integrating alkali treatment, fiber mapping, and intrinsic fiber properties, this work offers a unique perspective on the mechanical, physical, and thermal properties of biodegradable composites of reinforced polypropylene (PP) and plasticized poly (lactic acid) (PLA), with 25 wt% Kenaf (KBF), Bagasse, Hemp fibers and softwood fibers serving as a control. To enhance fiber–matrix interaction, fibers underwent alkaline treatment using 5% sodium hydroxide (NaOH) for one hour. The mechanical properties, including tensile strength, Young’s modulus, and impact strength, were evaluated alongside physical and thermal properties such as fiber mapping, brightness, heat deflection temperature (HDT), melting temperature, melt flow ratio (MFR), and melt flow index (MFI). Scanning electron microscopy (SEM) was used to assess the biocomposites’ morphology. The results showed that fiber reinforcement improved the tensile and impact strength of PP composites, particularly for treated Bagasse (6.6% and 22%) and Hemp (7% and 44.7%), while Kenaf exhibited minimal change, indicating its inherently high strength. A slight increase in tensile strength and Young’s modulus was observed in all PLA-based composites. The addition of 25% fiber enhanced the thermal properties of both treated and untreated fiber-reinforced composites. Among PP composites, those reinforced with treated fibers exhibited the highest HDT, with Kenaf achieving the best performance (124 °C), followed by Bagasse (93 °C). The HDT values for untreated fibers were 119 °C for KBF, 100 °C for softwood, 86 °C for Bagasse, and 79 °C for Hemp. PLA composites showed a slight increase in HDT with fiber reinforcement. Differential Scanning Calorimetry (DSC) revealed a slight decrease in melting temperature for PP composites and a slight increase for PLA composites. Fiber mapping analysis indicated that Kenaf had the highest aspect ratio, contributing to superior mechanical performance, while Hemp had the lowest aspect ratio and exhibited weaker mechanical properties. Overall, Kenaf and Bagasse fibers demonstrated superior mechanical and thermal properties, comparable to those of softwood fibers, whereas Hemp exhibited moderate performance. The variations in composites behavior were attributed to differences in fiber mapping, alkaline treatment, and the intrinsic properties of both the polymer matrices and the reinforcing fibers. These findings highlight the potential of treated natural fibers, particularly Kenaf and Bagasse, in enhancing the mechanical and thermal properties of biodegradable composites, reinforcing their suitability for sustainable material applications

Shape optimization with Ventcel transmission conditions: application to the design of a heat exchanger

This paper aims to optimize the shape of a fluid-to-fluid heat exchanger in order to maximize heat exchange under constraints of energy dissipation and volume. The novelty consists in taking into account the thin layer separating the two fluids by using Ventcel-type second order transmission conditions. The physical model is then a weakly coupled problem between the steady-state Navier-Stokes equations for the dynamics of the two fluids dynamics and the convection-diffusion equation for the heat. We provide a shape sensitivity analysis and characterize the shape derivatives involved. Finally, we demonstrate the feasibility and effectiveness of the proposed method through 3D numerical simulations