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ON RYSER'S CONJECTURE
No full textSubmittedWe provide new sufficient conditions under which Ryser's conjecture holds.</div
Analytic K-semistability and local wall-crossing
No full textInternational audienceAbstract For a small polarised deformation of a constant scalar curvature Kähler manifold, under some cohomological vanishing conditions, we prove that K -polystability along nearby polarisations implies the existence of a constant scalar curvature Kähler metric. In this setting, we reduce K -polystability to the computation of the classical Futaki invariant on the cscK degeneration. Our result holds on specific families and provides local wall-crossing phenomena for the moduli of cscK manifolds when the polarisation varies
Influence of particle geometry and polymer matrix composition on filament processing, rheological and electromagnetic properties: Towards 3D printable composites for microwave absorption: The work deals with new 3D printable composite materials applied to the development of complex geometries for microwave absorption. The influence of ferromagnetic particle geometry and polymer matrix composition on structural, rheological and electromagnetic properties is studied, aiming at elaborating composites with formulations presenting a good compromise between processability, 3D printability and electromagnetic performances. Finally, suspended geometries which could be used as electromagnetic absorbing surfaces to cover cavities on highly porous structures, are shaped using 3D printing by FDM. Their printability is discussed from structure-morphology-rheology-electromagnetism relationships of the filament and their holding during fused deposition.
No full textInternational audienceThe work deals with new 3D printable composite materials applied to the development of complex geometries for microwave absorption. The influence of ferromagnetic particle geometry and polymer matrix composition on structural, rheological and electromagnetic properties is studied, aiming at elaborating composites with formulations presenting a good compromise between processability, 3D printability and electromagnetic performances. Finally, suspended geometries which could be used as electromagnetic absorbing surfaces to cover cavities on highly porous structures, are shaped using 3D printing by FDM. Their printability is discussed from structure-morphology-rheology-electromagnetism relationships of the filament and their holding during fused deposition
Note sur une méthode non-paramétrique de détection de rupture
No full textThe purpose of this note is to present in details R codes to implement a non-parametric method for change-point detection. The proposed approach is validated from various perspectives using simulations. This method is a competitor to that of Pettitt ([3]) and is, like the latter, based on the Wilcoxon-Mann-Whitney test. It is used in [4] for the study of relatively short time series obtained from measurements on cores sampled in the bay of Brest.</div
Inverse identification of the hardening behavior with a fully 3D virtual fields method
No full textInternational audienceThis work investigates the use of the virtual fields method (VFM) to calibrate the hardening behavior of sheet metals up to rupture. Indeed, a few studies dealing with the VFM in a 2D framework have shown that after necking, the validity of the VFM is compromised, leading to inaccurate descriptions of the material hardening behavior. However, no study has yet quantified the validity of the VFM in a 2D framework. Therefore, it is essential to assess its limitations and, in turn, highlight the advantages of a 3D approach. This study investigates the influence of sample thickness on both 2D and 3D VFM, first by analyzing the evolution of the predicted load and then by evaluating the identification of material parameters in the Swift hardening law. In the first part, the 3D-VFM has shown to yield accurate results while using the 2D-VFM resulted in non-negligible relative errors after necking, showing that the error is correlated to the thickness. In the second part, the identification of the parameters of the Swift law was carried out using different combinations of three manually defined virtual fields. The material parameters identified with the 2D-VFM did not match the reference parameters while the 3D-VFM was able to correctly identify them in every instance
Method Validation: Extraction of Microplastics from Organic Fertilisers
No full textInternational audienceIt has been demonstrated that organic fertilisers could be a source of microplastics (MPs) in agricultural soils. These organic fertilisers comprise a diverse array of matrices including organic waste and by-products. Currently, there is no established methodology for the extraction of MP from these matrices. The present article aims to validate a standardised protocol for the extraction of MPs from a diverse range of complex, organic-rich samples. The protocol has been developed to ensure a high recovery of MPs, to preserve their integrity, and to eliminate organic particles that interfere with FTIR analyses. Spiked MPs sized 315-5000 µm were subjected to a two-step process involving chemical digestion (H 2 O 2 , 30% (w/v), 53 • C) and density separation (NaI, >1.60 g•cm -3 ). This resulted in a mean extraction rate exceeding 95%, with undigested matter remaining below 5%. No evidence of fragmentation was observed. Furthermore, the chemical nature of spiked microplastics is still perfectly interpretable from the FTIR spectra despite the different chemical treatments undergone. These findings thus validate the method for the microplastic range 315-5000 µm. However, a new method for reanalysing the project's data produced contrasting results, suggesting a significant drop in recovery rates for size ranges below 250 µm. This reanalysis approach constitutes the second innovation of this protocol, and enables a more critical analysis of the results obtained in publications on microplastics.</div
Biomechanical Assessment of Patients with Unilateral Total Knee Arthroplasty: A Preliminary Comparative Study
No full textInternational audienceAims: To identify the biomechanical differences between two types of prostheses (posterior-stabilized prosthesis with a fixed tibial plateau base and congruent prosthesis with a rotating tibial plateau) through functional performance measured by the 2-Minute Walk Test using the G-Sensor® inertial sensor (BTS Bioengineering S.p.A., Italy). Study Design: A prospective, observational, and comparative study with assessments conducted at two time points: 12 to 24 months after surgery. Place and Duration of Study: This study was carried out in a tertiary hospital in collaboration with a private university in the state of Goiás, Brazil, between March 2022 and December 2024. Methodology: This study evaluates and compares the functional performance of a sample of 36 patients using the 2-Minute Walk Test (2MWT) with an inertial sensor at two distinct time points, 12 to 24 months postoperatively. Patients were characterized by age, sex, BMI, postoperative time, laterality of the operated knee, and type of prosthesis used (fixed plateau or mobile plateau). Results: The study included 36 participants (21 women and 15 men; mean age 69.38 years, BMI 30.46), with 24 undergoing right knee arthroplasty. Half received fixed, and half rotated tibial plateau prostheses. Postoperative assessments at 17.31 and 42.80 months showed no significant differences in gait parameters between prosthesis types or sides. Pearson’s correlation revealed a strong negative relationship between test duration, cadence, and speed for rotating prostheses (r = -0.67/-0.66, P =.001) and between duration and speed for fixed prostheses (r = -0.8, P<.001). Conclusion: This study found no significant functional differences between fixed and rotating tibial plateau prostheses using the 2-Minute Walk Test. Both implants effectively restored knee mobility, emphasizing the utility of inertial sensors for clinical assessment. Further research with larger samples is needed to confirm these findings
Digital twin-based gearbox fault diagnosis using variational mode decomposition and dynamic vibration modeling
No full textInternational audienc
Global Economic Sovereignty Composite Index (ECO-SOV) 2024 Edition Third Research Report -Final Version
No full textThe Economic Sovereignty Composite Index (ECO-SOV) 2024 provides a comprehensive framework to measure and evaluate the economic independence and resilience of nations. It encompasses three core components—Proactive, Defensive, and Prosperity—that collectively assess a country's capacity for innovation, governance, and economic well-being. By examining these dimensions, the index highlights countries' ability to manage resources autonomously, withstand external shocks, and foster sustainable development. Key findings indicate significant regional disparities, with Europe and North America leading in economic sovereignty due to strong governance and innovation, while African and Arab nations face challenges such as weak governance, low innovation potential, and dependence on external resources. Notable performers include Sweden, the UAE, and Mauritius, whereas nations like Mali and Mauritania lag due to systemic governance and infrastructure issues. The report underscores the need for tailored policy interventions, focusing on strengthening governance, investing in human capital, fostering innovation, and addressing food sovereignty. These strategies aim to enhance economic resilience, reduce dependency, and promote sustainable growth, particularly in regions struggling with socio-economic vulnerabilities. The ECO-SOV index serves as a vital tool for policymakers to design informed strategies that align with national goals and global dynamics.</div
