University of Reims Champagne-Ardenne

Abstract Urban boundary-layer (UBL) processes are important to understand the complex interactions between the surface and atmosphere. Increased surface rough-ness and heat storage are typically attributed to the larger fraction of builtsurfaces in urban areas. Heatwaves lead to stronger heat storage and to extremeconvective UBLs, which is one of many applications where large-eddy simu-lations (LES) offe an accurate modelling methodology of complex turbulentcharacteristics in urban flw studies. This study investigates the structure, tur-bulence characteristics and measurement implications of UBL in Paris, France,during a heatwave in July 2022. High-resolution LES simulations (4–16 m) produced with PALM model system are evaluated against observations from the PANAME 2022 campaign,including eddy-covariance fluxe (EC), Doppler wind lidar (DWL) profilesand near-surface measurements from the M´et´eo-France observation network.In addition, wavelet analysis is used to examine resolved turbulent scales and vertical coupling at typical urban measurement heights. PALM reproduces the temporal variability of sensible heat fluxe at the SIRTA observatory with an 67.9 W m−2 and a bias of 34.5 W m−2, while momentum-related quantities show larger deviations, particularly during weaknighttime stratification Near-surface temperatures are well captured across the M´et´eo-France network, with an RMSE of 1.18 ◦C and mean bias of -0.63 ◦C. DWL comparisons show that PALM captures the growth and decay of the UBL at urban and suburban sites, with maximum UBL heights reach-ing 2.4 km in the city centre, approximately 10% higher than in more ruralconditions. Neighbourhood-scale turbulent motions (O(100 m)) dominate ver-tical transport during daytime convective conditions, with contributions fromlarger scales depending on measurement height and location. These resultsdemonstrate the capability of high-resolution LES to represent convective UBL dynamics during extreme heat and to assess the representativeness of urbanatmospheric measurements. Overall, this study provides one of the firs city toneighbourhood-scale LES analyses of an extreme convective UBL supportedby multiple observations. By linking resolved turbulent scales to vertical cou-pling and measurement height, the results infer when and where urban ECobservations remain representative under strongly unstable conditions. Thefinding offe practical guidance for the interpretation and design of urbanmeasurements and highlight the importance of resolving neighbourhood-scaleturbulence in urban flw modelling applications.

Wind energy conversion systems present several sources of disturbances and uncertainties due to nonlinear and complex dynamics. These phenomena can negatively impact the expected behavior of the controlled system and, consequently, lead to a decrease in maximum power extraction. This study focuses on designing a novel fractional-order control method for permanent magnet synchronous generator-based wind turbine systems. To improve the control performance in the presence of external disturbances and parametric variations, the proposed approach combines the robust super-twisting sliding mode technique with adaptive Type-3 fuzzy logic systems. Resulting from the evolution of Type-2 fuzzy logic systems, the interval Type-3 provides better approximation capabilities, especially in the presence of a higher degree of uncertainties. Combined with the super-twisting algorithm, fuzzy systems are used both to approximate unknown nonlinear functions and to replace discontinuous control laws. The system stability is ensured by the extended fractional Lyapunov criterion. Furthermore, a new lemma is proposed to demonstrate the finite time convergence. A comparative study including other well-known control techniques is presented to validate the effectiveness of the proposed approach.

Organizational transformation is a multifaceted process that involves altering an organization's structure, culture, processes, systems, and strategies to better adapt to internal and external changes. This transformative process is characterised by interprofessional interactions that aim to foster collective dynamics. The likelihood of organizational transformation failure is considerable, especially in pluralistic organizations. Our study's research question centred on the interactional mechanisms that come into play in the dynamics of organizational transformation within hospitals during a health crisis, treating the crisis as a valuable learning opportunity. Following a 6-month observation period, 28 semi-structured interviews were conducted between September 2021 and December 2022 with various professionals from different hierarchical levels and professional categories in two French hospitals. This study emphasises the mechanisms that facilitate the development of a social structure and social systems in pluralistic organizations and govern the individual and collective actions that regulate the process of organizational transformation.

BackgroundThe evolution of medical students’ population and their choices of medical residency is poorly documented in France. The objective of this study was to perform a retrospective analysis of medical student’s residency choices at their national ranking exam (NRE) once they have completed six years of theoretical and practical medical training.MethodsPublished choices after the French NRE were processed from 2011 to 2023. A longitudinal follow-up of the median rank of affected students for each medical speciality and each training university hospitals is presented. Demographics and gender statistics are also presented. Violin plots, heatmaps and bump charts were used for a better analysis. Mann–Kendall test was used for trend analysis.ResultsWe analyzed choices of more than 100,000 students and show that men were more likely to have a better ranking, though with a non homo-geneous distribution compared to women who were more homogeneously distributed. We also proved that younger students better performed at the exam. We observed an unprecedented increased attractiveness of medical gynecology (+ 14 places, p = 0.007) as well as anesthesiology and resucitation (+ 13 places, p = 0.008).Vascular medicine (+ 4 places, p = 0.014), otorhino-laryngology (+ 2 places, p = 0.041) and dermatology (+ 5 places, p = 0.019) also significantly gained attractivity over the study period contrary to neurosurgery (-23 places, p = 0.023) and infectious diseases (-8 places, p = 0.048). Medical schools of Rennes (+ 7 places, p = 0.005) and Caen (+ 3 places, p = 0.048) have been gaining interest over the whole period while Grenoble (-5 places, p = 0.013), Paris (-5 places, p = 0.0083) and Limoges (-4 places, p = 0.006) have been significantly loosing attractivity.ConclusionThis work provides an overview of choices trends at the French medical NRE and illustrates for the first time the evolution of medical students’ demography and residency choices over a thirteen-year period.