Thorium divanadate dihydrate, Th(V2O7)(H2O)2

The title compound, Th(V2O7)(H2O)2, was synthesized by a hydro­thermal reaction. The crystal structure consists of ThO7(OH2)2 tricapped trigonal prisms that share edges, forming [ThO5(OH2)2]n chains along [010]. The edge-sharing ThO7(OH2)2 polyhedra share one edge and five vertices with the V2O7 divanadate anions having a nearly ecliptic conformation parallel to [001]. This results in an open framework with the water mol­ecules located in channels. O—H⋯O hydrogen bonding between water molecules and framework O atoms is observed. Bond-valence-sum calculations are in good agreement with the chemical formula of the title compound

Apport de l’IRM 3T 3 D Flair dans le diagnostic des syndromes vestibulaires aigus (SVA)

Objectif :L’objectif de notre mémoire est de rechercher des corrélations entre d’une part la clinique des vertiges de type névrite vestibulaire avec les explorations vestibulaires et d’autre part l’imagerie par IRM 3 teslas selon un protocole dédié pour vérifier la concordance diagnostic ; le but étant de rechercher une concordance localisatrice. Ce travail a été mené dans le cadre d’une étude prospective nommée SURDIVER du 24 mai 2019 au 15 février 2021 dans le service ORL-CCF du CHU de Clermont-Ferrand en collaboration avec le service de Radiologie du CHU.Matériels et méthodes : 28 patients souffrant de vertige avec un tableau de névrite vestibulaire isolée et 20 patients présentant un tableau de névrite vestibulaire associée à une surdité concomitante ont été inclus. Un bilan audiovestibulaire comportant : une audiométrie tonale et vocale, des otoémissions acoustiques provoquées, des potentiels évoqués auditifs précoces, des potentiels évoqués otolithiques myogéniques, d’une vidéonystagmographie. Une IRM centrée sur le labyrinthe avec des séquences T1, T2, 3D FLAIR et des acquisitions précoces (10 min) et tardives (4 h) après injection de gadolinium.Résultats :Au total, 48 patients ont été inclus dans l’étude avec un sex-ratio de 1.24 atteintes de l’oreille droite et à gauche.5 vrais cas de névrite ont été identifiés à l’imagerie. Il a été retrouvé 27 % de corrélation entre les PEO et l’analyse IRM du vestibule comprenant le saccule.Il a été établi une corrélation évaluée à 53,7 % entre les tests caloriques et l’analyse IRM des canaux semi-circulaires.Un pattern radiologique vasculaire a été retrouvé chez 70 % des patients souffrant de syndrome cochléo-vestibulaire.Conclusion :L’IRM 3T 3D permet d’obtenir des informations localisatrices et étiologiques précises que l’on obtient difficilement par des explorations classiques.Les causes vasculaires sont très majoritaires dans les syndromes cochléo-vestibulaires, au contraire des névrites vestibulaires où la cause inflammatoire est deux fois plus fréquente.Il n’y a pas été établi de lien entre la gravité clinique et la présence d’hypersignal à l’IRM

A new T–S fuzzy model based robust output-feedback stabilizing controller for fractional-order systems

International audienceBy using Takagi–Sugeno (T–S) fuzzy set approach, this paper proposes a robust dynamic output feedback (DOF) control for nonlinear fractional-order systems satisfying 0<α<1. First, using a Fractional Lyapunov function, the novel DOF controller guarantees the stability of the closed-loop system. The proposed approach allows avoiding appearance of crossing terms between the controller’s and the T–S system’s input matrices leading to easier LMI formulation. Second, a new controller is developed by combining a fuzzy dependent Lyapunov function and some special derivations on the controller parameters. This leads to some sufficient conditions in the form of strict linear matrix inequalities (LMIs). When compared with previous work, the proposed method not only has abilities to handle the fuzzy system with the time-derivatives of the membership functions but also can deal with the parametric uncertainties effectively. Simulation examples are provided to demonstrate the validity of the proposed conditions

Maximum Power Point Tracking of a Photovoltaic System Using State Feedback Gain Fuzzy Control

International audienc

Maximum Power Point Tracking of a Photovoltaic System Using State Feedback Gain Fuzzy Control

International audienc

Output Feedback H_\infty Control Design For Polynomial T–S Systems: A Novel SOS Approach

International audienceThis paper considers the design of a static output feedback (SOF) H_\infty controller for a polynomial Takagi-Sugeno(T–S) system in the continuous-time setting. The sought SOF controller guarantees asymptotic stability and H_\infty performance of the closed-loop system. Sufficient conditions for the existence of such SOF controllers are derived, in the form of sum-of-squares (SOS) using polynomial Lyapunov functions (PLF). These conditions do not include an iterative algorithm or an equality constraint which leads to a more tractable solution. The proposed gain is obtained by means of less conservative conditions than existing ones. This is illustrated through some numerical examples which demonstrate, at the same time, the applicability of the suggested design approach

T-S Fuzzy Model-Based Robust Output-Feedback Control for Fractional-Order Systems

International audienceThis paper proposes a robust dynamic output feedback control for uncertain fractional-order systems based on an uncertain Takagi-Sugeno fuzzy model with a fractional-order satisfying 0<α<1. By means of a specific Lyapunov function, some sufficient conditions, expressed as linear matrix inequalities, are derived to allow the design of a stabilizing dynamic output feedback controller for the said fractional-order system. When compared with previous work, the proposed method not only shows abilities to handle the fuzzy system with the time-derivatives of the membership functions but also can deal with the parametric uncertainties effectively. A simulation example is given to demonstrate the validity of the proposed conditions

Maximum Power Point Tracking of a Photovoltaic System Using State Feedback Gain Fuzzy Control

International audienceAn effective Maximum Power Point Tracking (MPPT) technique, that can be used in a variety of environmental conditions, is tackled with in this note. To this aim, an MPPT control based on a T-S fuzzy model is applied improving thus the performance and the efficiency of a solar photovoltaic (PV) generator. The nonlinear system's dynamics are embedded in a T-S fuzzy model. Sufficient criteria for designing such fuzzy control policy are presented in terms of linear matrix inequalities based on a quadratic Lyapunov function combined with some helpful slack variables (i.e. dilated quadratic LMI conditions). The proposed method reduces tracking time while overcoming the oscillation that usually appear near the maximum powerpoint. Besides, the simulation of a photovoltaic system using the proposed control policy demonstrates the efficiency of the approach even in the case of climate changes

Photovoltaic System's MPPT Under Partial Shading Using T-S Fuzzy Robust Control

International audienceThis paper deals with a T-S fuzzy robust control achieving maximum power point tracking (MPPT) for photovoltaic (PV) systems under partial shading situations. The aim is to track global maximum power point (GMPP). The T-S fuzzy robust control consists in an optimization approach that overcomes the well-known perturb and observe (P&O) technique drawbacks, such as the decreased tracking efficiency and transient oscillations. For this aim, a photovoltaic generator (PVG) with a DC-DC boost converter and battery energy storage devices are considered. The optimum trajectory is generated using a T-S fuzzy reference model, which must be followed to obtain optimal powerpoint. Solving a set of linear matrix inequalities (LMIs) yields the sought controller gains. A simulation is carried out to show that the tracking performance of the proposed T-S fuzzy robust control is assessed for various partial shading patterns. The results confirm that the T-S fuzzy robust H∞ control strategy ensures global MPP convergence. Furthermore, when compared to the existing solutions, simulations proved that it has better performances