Improved control strategy of DFIG-based wind turbines using direct torque and direct power control techniques

This paper presents different control strategies for a variable-speed wind energy conversion system (WECS), based on a doubly fed induction generator. Direct Torque Control (DTC) with Space-Vector Modulation is used on the rotor side converter. This control method is known to reduce the fluctuations of the torque and flux at low speeds in contrast to the classical DTC, where the frequency of switching is uncontrollable. The reference for torque is obtained from the maximum power point tracking technique of the wind turbine. For the grid-side converter, a fuzzy direct power control is proposed for the control of the instantaneous active and reactive power. Simulation results of the WECS are presented to compare the performance of the proposed and classical control approaches.Peer reviewedFinal Accepted Versio

Rotator Cuff Deficient Arthritis of the Glenohumeral Joint

Rotator cuff deficient arthritis of the glenohumeral joint, especially cuff tear arthropathy, has proved a challenging clinical entity for orthopaedic surgeons ever since Charles Neer originally detailed the problem in 1983. Understanding has improved regarding the pathophysiology and pathomechanics underlying cuff tear arthropathy. Surgical reconstruction options can lead to excellent outcomes for patients afflicted with these painful and functionally limited shoulders. Humeral hemiarthroplasty and reverse total shoulder arthroplasty have jumped to the forefront in the treatment of cuff tear arthropathy. As studies continue to look at the results of these procedures in cuff tear arthropathy, existing indications and treatment algorithms will be further refined. In this article the history and pathophysiology of cuff tear arthropathy are reviewed. Additionally, the clinical findings and results of surgical reconstruction are discussed

Infraglenoidal scapular notching in reverse total shoulder replacement: a prospective series of 60 cases and systematic review of the literature

<p>Abstract</p> <p>Background</p> <p>The impact of infraglenoidal scapular notching in reversed total shoulder arthroplasty (RTSA) is still controversially discussed. Our goal was to evaluate its potential influence on subjective shoulder stability and clinical outcome. We hypothesized that subjective instability and clinical outcome after implantation of RTSA correlates with objective scapular notching.</p> <p>Methods</p> <p>Sixty shoulders were assessed preoperatively and at minimum 2-year follow-up for active range of motion and by use of the Oxford instability score, Rowe score for instability, Constant score for pain, Constant shoulder score, DASH score. All shoulders were evaluated on anterior-posterior and axillary lateral radiographic views. These X-ray scans were classified twice by two orthopaedic surgeons with respect to infraglenoidal scapular notching according to the classification of Nerot. Notching was tested for correlation with clinical outcome scores to the evaluated notching.</p> <p>Results</p> <p>We found no significant correlation between infraglenoidal scapular notching and clinical outcomes after a mid-term follow-up from 24 to 60 months, but at the final follow-up of 60 months and more, we did see statistically significant, positive correlations between infraglenoidal scapular notching and the Constant pain score as well as active range of motion. At mean follow-up of 42 months (range from 24 to 96 months) we found no significant correlation between subjective instability and infraglenoidal scapular notching.</p> <p>Conclusions</p> <p>We conclude that patients' subjective impression on their shoulders' stability is not correlating with radiological signs of infraglenoidal scapular notching. Nevertheless clinical parameters are affected by infraglenoidal scapular notching, at least in the long term</p

Simulation de la couche limite hypersonique autour d’un corps émoussé du type sphère-cylindre

Une des contraintes majeures intervenant dans la conception de la protection thermique d’engin spatial hypersonique est liée à l’échauffement de la paroi. Elle est du principalement à la présence de chocs forts au sein de l’écoulement, à la dissipation visqueuse dans les couches limites et aux effets de thermochimie. L’importance de la différence de température entre la paroi et l’écoulement est source de flux de chaleur internes, transmis en partie à la paroi à travers la couche limite. Un des outils numériques qui permet une telle prédiction et simule la couche de choc complète est constitué par les méthodes de résolution des couches limites hypersoniques à la base des schémas à propriété TVD. Cette recherche concerne la simulation numérique d’écoulements hypersoniques visqueux et réactifs autour de configuration du type sphère – cylindre. Le but est d’étudier les variations du flux de chaleur, de la pression, des contraintes et des concentrations de certaines espèces ; et d’analyser la sensibilité de la couche limite hypersonique à la température de la paroi, aux différents modèles thermodynamiques et chimiques.Mots clés : fluide dynamique; écoulement réactif hypersonique; ondes de choc; thermochimique

Conflit postéro-supérieur de l'épaule chez le sportif: résultats du débridement arthroscopique

The painful shoulder is a well-recognized clinical entity in throwers although the pathogenic mechanisms involved are still debated. In 1991 Walch then Jobe developed the concept of posterosuperior impingement to explain lesions observed arthroscopically. This impingement between the deep aspect of the supraspinatus tendon and the glenoid occurs during loaded arm movements. The purpose of this work was to study the different types of lesions observed arthroscopically and to analyse outcome after arthroscopic debridement