Les Fédérations sportives internationales. centres de décision et stratégies du pouvoir

L'analyse de la répartition spatiale des sièges et des présidences de Fédérations sportives internationales met en évidence des stratégies politiques dans l'organisation mondiale des sports

Prospects of implementing xAPI as a solution for progress tracking in a Blended Learning environment

Learning and development is an exciting world of never ending change, challenges, and trends. Businesses are currently attempting to adapt to the rapid digitization of workplaces. Therefore, L&D (Learning and Development) professionals are making learning material available to learners when and where they need it. According to two of “The State of Learning and Development” reports, published by “InSync Training” in 2016 and 2017 [1,2], the L&D industry is experiencing a shift from traditional approaches (e.g. classrooms, multi-day workshops…), to more modern learner-centered approaches (e.g. blended learning, mobile learning…). The aforementioned reports emphasize on the importance of implementing blended learning. It’ a learner-centered approach that matches different parts of the educational content to their most appropriate delivery methods (e.g. classroom interaction, article, video, audio, video game…) and sequences the resulting learning activities into a complete program of instruction. Although it’s currently a very popular trend given its benefits, there are multiple challenges it’s facing. In this article, we’ll explain the different benefits and challenges of blended learning. After that we’ll explore the prospects of implementing the Experience API (xAPI in short), a new open source specification for learning technology published by ADL (Advanced Distributed Learning) in 2013 [3], as a solution to improve the effectiveness and efficiency of blended learning

Identification of internal cracks in a three-dimensional solid body via Steklov–Poincaré approaches

International audienceThis Note deals with the identification of internal planar cracks inside a three-dimensional elastic body via two approaches relying on domain decomposition using elastostatic measurements. These approaches consist in recasting the problem in terms of primal or dual Steklov-Poincaré equations. The primal approach is a straightforward continuation to the elastic Cauchy problem of the work presented in J. Ben Abdallah (2007) [1] which is devoted to the Cauchy problem for the scalar Laplace equation. The numerical performances of these formulations are compared

Quantitative Analysis of Semicrystalline Blends SAXS Data: Theoretical Modeling versus Linear Correlation Function

This paper compares the results yielded by two methods of small-angle X-ray scattering data analysis for semicrystalline polymer blends. The first method is based on the use of a theoretical modeling for isotropic samples and a subsequent curve fitting. The second one is a more familiar method, based on the calculation of the linear one-dimensional correlation function. The experimental material considered for this purpose deals with a series of semi-crystalline blends of poly(vinylidene fluoride) and poly(methyl methacrylate), with a PVDF content covering the range 50 wt%–100 wt%. The results obtained by both calculation methods are systematically confronted to the crystallinity degrees deduced from wide angle X-ray scattering patterns

Concept and Feasibility Evaluation of Distributed Sensor-Based Measurement Systems Using Formation Flying Multicopters

Unmanned aerial vehicles (UAVs) have been used for increasing research applications in atmospheric measurements. However, most current solutions for these applications are based on a single UAV with limited payload capacity. In order to address the limitations of the single UAV-based approach, this paper proposes a new concept of measurements using tandem flying multicopters as a distributed sensor platform. Key challenges of the proposed concept are identified including the relative position estimation and control in wind-perturbed outdoor environment and the precise alignment of payloads. In the proposed concept, sliding mode control is chosen as the relative position controller and a gimbal stabilization system is introduced to achieve fine payload alignment. The characterization of the position estimation sensors (including global navigation satellite system and real-time kinematics) and flight controller is carried out using different UAVs (a DJI Matrice M600 Pro Hexacopter and Tarot X4 frame based Quadcopter) under different wind levels. Based on the experimental data, the performance of the sliding mode controller and the performance of the gimbal stabilization system are evaluated in a hardware-in-the-loop simulation environment (called ELISSA). Preliminary achievable control accuracies of the relative position and attitude of subsystems in the proposed concept are estimated based on experimental result

Eucalyptus oleosa Essential Oils: Chemical Composition and Antimicrobial and Antioxidant Activities of the Oils from Different Plant Parts (Stems, Leaves, Flowers and Fruits)

Essential oils obtained by hydrodistillation from the different parts (stems, adult leaves, immature flowers and fruits) of Eucalyptus oleosa were screened for their antioxidant and antimicrobial properties and their chemical composition. According to GC-FID and GC-MS, the principal compound of the stem, immature flowers and the fruit oils was 1,8-cineole, representing 31.5%, 47.0% and 29.1%, respectively. Spathulenol (16.1%) and γ-eudesmol (15.0%) were the two principal compounds of adult leaves oil. In the DPPH (1,1-diphenyl-2-picrylhydrazyl) assay, the oils of the four parts showed moderate antioxidant activity. In the ABTS (2,2’-azinobis-3-ethylbenzothiazoline-6-sulphonate) assay, the most active part was the adult leaves, with a IC50 value 13.0 ± 0.6 mg/L, followed by stems (IC50 = 43.5 ± 1.4 mg/L). The essential oils showed a better antibacterial activity against Gram-positive and Gram-negative bacteria, and a significant antifungal activity also was observed against yeast-like fungi. A strong correlations between oxygenated monoterpenes and antimicrobial activity (especially 1,8-cineole) were noted (R2 = 0.99, 0.97 and 0.79 for B. subtilis, P. aeruginosa and C. albicans, respectively)

Nonlinear Control Strategies of an Autonomous Double Fed Induction Generator Based Wind Energy Conversion Systems

In the last few decades, among the wide range of renewable energy sources, wind energy is widely used. Variable speed wind energy conversion systems based on double fed induction generator have a considerable interest mostly in case of islanded networks and/or isolated applications. In this paper, as a means to supply remote areas, an investigation of a wind energy conversion system (WECS) based on a double fed induction generator (DFIG) is carried out. The presence of both wind turbine aerodynamics and DFIG coupled dynamics causes strong nonlinearities in the studied system. Wind speed and demanded power variations have a major impact on the quality of the produced energy. In order to control and maintain the stator output voltage and frequency at their nominal values (220 V/50 Hz) under wind speed and load variations, this work presents a study of three kinds of controllers: PI, Back-Stepping and Sliding Mode controllers. These controllers are integrated in the studied system and a comparison of their dynamic performances has been developed. Moreover, in order to ensure the rotor side converter safety on the one hand and to guarantee an optimal operation of the DFIG on the other hand, a management strategy is proposed in this work. Simulation results are performed using Matlab/Simulink environment and show the effectiveness and the accuracy of each controller compared to others mainly with the presence of wind speed and load demand variations

Upravljanje otporno na kvarove asinkronog motora zasnovano na deskriptorskom observeru

This paper presents an active Fault Tolerant Control (FTC) strategy for induction motor (IM) that ensures Field Oriented Control (FOC) and offset the effect of the sensor faults despite of the load torque disturbance. The proposed approach uses a fuzzy descriptor approach to estimate simultaneously the system state and the sensor fault. The physical model of IM is approximated by the Takagi-Sugeno (T-S) fuzzy technique in the synchronous d-q rotating frame with field-oriented control strategy. The stability conditions are analyzed using Lyapunov theory. The controller and observers gains are calculated by solving a set of Linear Matrix Inequalities (LMIs). Finally, the effectiveness of the proposed strategy have been illustrated in simulation and experimental results.U ovom radu je predstavljena strategija upravljanja otpornog na kvarove za asinkroni motor koja omogućuje vektorsko upravljanje bez pogreške uslijed kvara senzora i postojećeg poremećaja momenta tereta. Predloženi pristup koristi neizraziti deskriptor za estimaciju stanja sustava i kvara senzora. Fizikalni model asinkronog motora s vektorskim upravljanjem aproksimiran je korištenjem Takagi-Sugeno modela u rotirajućem d-q koordinatnom sustavu. Uvjeti stabilnosti analizirani us korištenjem Ljapunovljeve teorije. Konstante pojačanja regulatora i obzervera su izračunati rješavanjem skupa linearnih matričnih nejednadžbi. Učinkovitost predložene strategije je ilustrirana simulacijskim i eksperimentalnim rezultatima

Drug Abuse-Induced Cardiac Arrhythmias: Mechanisms and Management

Toxicomania is a worldwide emerging problem threatening young population. Several reports highlighted its hazardous cardiovascular effects. Sudden cardiac death secondary to cardiac arrhythmias is the most occupying issue. Different forms of cardiac rhythm disorders may be induced by illicit drug abuse according to the type of drug and the mechanism involved. In this review, we exposed the main ventricular and supraventricular arrhythmia complicating the common recreational drugs, and we explained their different mechanisms as well as the particularities of management