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Open Questions on Ion–Neutral Collisions and Coupling in the Lower Thermosphere–Ionosphere: Electrodynamics, Energetics and Dynamics
No full textInternational audienceThe Lower Thermosphere-Ionosphere (LTI) is the interface region between the Earth's atmosphere and space. It is modulated by the energy and momentum deposition from the magnetosphere above and by the impacting waves from the lower atmosphere. The LTI region is defined by the co-existence and interaction of neutral and ionized species within the region's electric and magnetic fields. This interplay results in unique and complex interactions between neutrals and plasmas, that are not fully understood and quantified to this date. In this paper we present an overview of some of the most important open questions related to ion/neutral coupling and the resulting collisional electrodynamics, collisional energetics and collisional dynamics processes. We outline the key reasons for addressing these questions, and highlight methodologies that can lead to their closure in the upcoming years.</div
L'adoption par l'ex-compagne : l'opportunité du contrôle de proportionnalité
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Kafala homologuée : vers une approche fonctionnelle de la décision de justice fondée sur l'intérêt de l'enfant
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Artificial intelligence-based group decision making to improve knowledge transfer: the case of distance learning in higher education
No full textFNEGE 4, ABS 1International audienceIn this paper, we propose a method based on multicriteria classification and a dominancebased rough set approach (DRSA) to support teachers in decision making. The objective is to use teachers’ knowledge and preferences to identify ‘atrisk students’, i.e. students who are likely to drop out, and ‘leader students’, i.e. students who are likely to help their peers, in distance learning. The proposed method is composed of two phases: phase I builds collective decision rules from teachers’ preferences, and phase II classifies students into two decision classes: ‘atrisk students’ and ‘leader students’. This method was designed, tested, and validated in higher education, with teachers who have acquired rich experience in teaching in online-synchronous mode since the Covid-19 pandemic
State of Health Evaluation of Lithium-Ion Batteries Using the Statistical Properties of the Voltage
No full textInternational audienceConventional indicators of battery health, such as capacity and energy, are difficult to measure directly and are therefore often estimated. This article proposes assessing lithium-ion battery health using the statistical properties of the voltage across the battery terminals, a measurement already available in battery management systems. The evolution of the voltage probability density function during the cycle is assessed using Kullback–Leibler divergence (KLD) as a health indicator. It is studied for two battery chemistries (Lithium iron Phosphate (LFP) and Nickel Manganese Cobalt (NMC)). The batteries are subjected to cycles with a dynamic current profile derived from globally harmonised test cycles for light vehicles (WLTC). Spearman’s correlation coefficients, above 86% for NMC cells and 74% for LFP cells, also indicate that this new health indicator is strongly correlated with conventional measurements of battery health (capacity or energy). The analysis also shows that the divergence not only closely follows the degradation trend even at high noise levels (SNR = 10 dB) but is also insensitive to noise levels higher than 30 dB
Decadal variability in mid-atmosphere temperature derived from continuous lidar observations
No full textInternational audienceNine Rayleigh scattering-based lidars, some of which are affiliated with the Network for the Detection of Atmospheric Composition Change (NDACC) and the Atmospheric Remote Sensing in Stratosphere and mesosphere (ARISE) for monitoring stratospheric ozone, have been routinely observing temperature profile variations in the middle atmosphere for many years with excellent vertical resolution (around one kilometer). These observatories are located at various points around the globe from north to south: ALOMAR in Norway, Kühlungsborn in Mecklenburg-Western Pomerania Germany, Hohenpeissenberg in Bavaria Germany, Haute-Provence in southern France, Purple Crow in the Canadian London Ontario, Table Mountain in California, Mauna Loa in Hawaii, Maido on Reunion Island, Coral in Tierra del Fuego Argentina . These unique datasets have made it possible to update the climatology and seasonal variations of middle atmosphere temperatures between 30 and 80 km at several latitudes with significantly long databases that could be compared with numerical models. The behavior is similar at all sites, with a marked annual variation in the stratosphere of up to 6K, little variation around the stratopause ( 2K) and a continuously increasing seasonal variation in the mesosphere of up to 16 K for some sites. These seasonal cycles are halved in tropical sites. The QBO (Quasi-Biennial Oscillation) is clearly visible in the temperature series and causes variations that can exceed 1 K. The temporal extent of the series, spanning several 11-year solar cycles, made it possible to extract variations associated with changes in solar activity on the vertical temperature profile, showing signatures of up to 4 K. In summer at mid and low latitudes, the signature is weak and around 1 K, in line with the expected photochemical effects. In winter, the response at mid-latitudes confirms previous observations of a negative effect. At higher latitudes, even larger signatures are observed, confirming the effect of feedback in the atmospheric response. This analysis also allowed us to update the quantification of decadal trends in the middle atmosphere, which show differences depending on latitude. These fluctuations become significant when the series are longer than one solar cycle. Observations at mid and low latitudes confirm the significant detection of a cooling ranging from about 1 K/decade in the upper stratosphere and increasing in the mesosphere to several K/decade. At mid latitudes, the three sites show good agreement, but in tropical/subtropical regions, greater variability is observed. In particular, in the mesosphere, observations obtained over Reunion Island in the tropical region in the southern hemisphere show cooling of up to 5 K/decade in the mesosphere, significantly greater than at other sites. Polar lidar data show that in these regions the trend is towards warming, with values remaining around 2K/decade, mainly in the mesosphere however the variability is large and the sampling larger in winter
Relations entre ruralité et biodiversité. Le succès de la patrimonialisation en commun de la plaine de Versaillespour une meilleure protection de sa biodiversité
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Review of "On the intrinsic approaches in mechanics"
No full textThis is the open review or article https://doi.org/10.46298/jtcam.15729 published in JTCA