Modeling and control of double star induction machine by active disturbance rejection control

This paper aims to contribute to the modeling and control of the double star induction machine (DSIM) by a robust method called active disturbance rejection control (ADRC). The ADRC has become in the last decade one of the most important techniques of regulation. This method is based on the use of an ESO (Extended State Observer) which estimates in real-time and at the same time the external disturbances and the errors due to the variations of the parameters of the machine and to the uncertainties of modeling. The two stators of DSIM are powered by three-phase inverters based on transistors and MLI control and the entire system is modeled in Park's reference. We analyze in the Matlab/Simulink environment the dynamic behavior of the system and the different ADRC controllers under different operating conditions. The result has demonstrated the performance and effectiveness of the ADRC

Comparative study of power smoothing techniques produced by a wind energy conversion system

This paper aims to present and compare two techniques used to smooth the injected power in the grid from a doubly-fed induction generator (DFIG) based conversion system. The first technique based on an inertial storage system while the second is founded on limiting the power captured by the wind turbine. The overall system composed of a wind energy conversion system (WECS) allowing to convert a wind power into electric power. It is controlled by two converters, grid side converter and a rotor side converter, both are controlled by sliding mode. The storage system is used to consume power which exceeds the setpoint due to storing it or producing more in the event of a lack, the system is controlled through the flywheel side converter by the sliding mode. Numerical simulations were carried out using Matlab/Simulink software

Polymer-Clay Nanocomposites: Exfoliation and Intercalation of Organophilic Montmorillonite Nanofillers in Styrene–Limonene Copolymer

Nanocomposites from Styrene-Limonene copolymers and Algerian organophilic-clay named Maghnite-CTA+ (Mag-CTA+), were prepared by in-situ polymerization using different amounts (2, 5, and 10% by weight) of clay and Azobisisobutyronitrile (AIBN) as a catalyst. The Mag-CTA+ is an organophilic silicate clay prepared through a direct exchange process, using Cetyltrimethylammonuim bromide (CTAB) in which it used as green nano-filler. The preparation method of nanocomposites was studied in order to determine and improve structural, morphological and thermal properties of Sty-Lim copolymer. The struc ture and morphology of the obtained nanocomposites (Sty-Lim/Mag) were determined using Fourier trans form infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electronic microscopy (SEM) and transmission electronic microscopy (TEM). The analyses confirmed the chemical modification of clay layers and the intercalation of Sty-Lim copolymer within the organophilic clay sheets. Exfoliated structure was obtained for the lower amount of clay (2 wt %), while intercalated structures were detected for higher amounts of clay (5 and 10 wt %). The thermal properties of the obtained nanocomposites were studied by thermogravimetric analysis (TGA) and show a significant improvement in the thermal stability compared with the pure copolymer. The obtained nanocomposites show an optimal degradation temperature of 320°C.info:eu-repo/semantics/publishedVersio

Syndrome de fatigue oculaire numérique : impact du confinement durant la pandémie COVID-19

Le syndrome de fatigue oculaire est un ensemble de symptômes traduisant une gêne oculaire et visuelle suite à une utilisation prolongée et quotidienne des appareils multimédia . En effet , le e-learning  et le télétravail sont devenus incontournables en période de confinement durant la pandémie de la covid-19 sans préparation préalable . Le but de notre travail est de rapporter l’impact du confinement sur la santé oculaire de notre population . Il s’agit d’une étude prospective portant sur 212 cas , durant la période du confinement de mars à juin 2020. La population cible comportait toute personne confinée ayant eu recours au télétravail et e-learning . Le secteur le plus touché était celui de l’enseignement : 49% des enseignants et étudiants tous niveaux confondus , suivi des employés de bureau (28,5%) . Tous nos cas ont été confinés ; 76% des cas ont rapporté l’utilisation de plus de 4 écrans par jour et pour une durée de plus de 6 heures dans 40 % des cas sans pause . Les symptômes décrits étaient une rougeur avec photophobie et larmoiement dans 45% des cas. 39,6% des cas ont consulté un ophtalmologiste, 34,4 % des cas ont arrêté leur activité jusqu’à amélioration de la symptomatologie .Plusieurs options thérapeutiques sont proposées (correction optique à filtre , manœuvre 20/20/20 , substitution en larmes artificielles..) . Compte tenu de la prévalence élevée du syndrome de fatigue oculaire numérique , il est primordial que la maladie soit prise en compte par les ophtalmologistes

TUBERCULOSE OCULAIRE

Ocular manifestations in tuberculosis are rare, they are observed only in 1 to 2% of cases. With the advent of AIDS, ocular affections in tuberculosis have been encountered with increased frequency. We report a serie of six cases of ocular tuberculosis admitted in our Ophthalmology department between 2004 and 2006. Among the six cases of tuberculosis eye, there is a notion of tuberculosis contagion in one case, extra ocular tuberculosis in three cases. A palpebral nodule is found in one case; follicular conjunctivitis in one case; interstitial keratitis in one case, an uveitis in three cases. The diagnosis is based on the clinical, para-clinical arguments. Chemotherapy was instituted in all patients with treatment-steroidal anti-inflammatory in three cases. Evolution was favourable in five cases. Ocular tuberculosis is an affection less often than before. A resurgence in recent years due to the spread of AIDS and multi-resistant forms. is noted Uveal involving is the most common ocular presentation. The diagnosis is based on a clinical, biological, para-clinical and histological arguments Tuberculosis treatment is principally related to preventive measures. The authors report ocular tuberculosis diagnostic problems on the necessity of regular ophthalmic examination of patients under treatment.Les manifestations oculaires au cours de la tuberculose sont rares, puisqu’elles ne sont observées que dans 1 à 2% des cas. Cette atteinte oculaire connaît actuellement une recrudescence avec l’avènement du SIDA. Nous rapportons une série de six cas de tuberculose oculaire colligée dans notre service d’Ophtalmologie Adulte entre 2004 et 2006. Sur les six cas de tuberculose oculaire, on retrouve une notion de contage tuberculeux dans un cas, une tuberculose extra oculaire dans trois cas. Un nodule palpébral est retrouvé dans un cas ; une conjonctivite folliculaire dans un cas ; une kératite interstitielle dans un cas ; une uvéite dans trois cas.  Le diagnostic est posé sur l’aspect clinique et sur un faisceau d’arguments para-cliniques. La chimiothérapie a été instituée chez tous les malades avec un traitement anti-inflammatoire stéroïdien dans trois cas. L’évolution a été favorable dans cinq cas sur six. La tuberculose oculaire est une affection moins rare qu’auparavant. Elle connaît une recrudescence ces dernières années due à l’extension du SIDA et des formes multi résistantes. L’atteinte du tractus uvéal est la manifestation oculaire la plus fréquente. Le diagnostic repose sur un faisceau d’arguments cliniques, biologiques, para-cliniques et histologique. Le traitement de la tuberculose est d’abord préventif. Les auteurs insistent sur les problèmes diagnostiques de la tuberculose oculaire et sur la nécessité d’une surveillance ophtalmologique régulière des patients sous traitement antibacillaire

TUMEUR FIBREUSE SOLITAIRE DE L’ORBITE A PROPOS D’UN CAS AVEC REVUE DE LITTERATURE

Background: the solitary fibrous tumor (SFT) is a spindle-cell tumor that very rarely involves the orbit. We report a case that we compare to reports in the literature. Case: a 43 year old man presented a conjunctival inflammation of the left eye developing over 14 months with progressive proptosis. Magnetic resonance imaging revealed a retroocular mass, which showed isointensity on T1 and hyperintensity on T2. Histological examination of the lesion confirmed the diagnosis of the SFT of the orbit. The patient was doing well without recurrence after 12 months. Discussion: The diagnosis of SFT is histological. It is a mesenchymal tumor. Immunohistochemically, the tumor cells are strongly positive for CD34 and vimentin. Conclusion: The SFT of the orbit is a very rare and generally benign tumor. immunohisochemically differentiated from other spindle-cell tumors of the orbit . The treatment is a complete surgical excision, and long-term follow-up is necessary because recurrence may appear long after treatment.(TFS) est une tumeur mésenchymateuse ubiquitaire exceptionnellement retrouvée dans l’orbite. Nous rapportons un nouveau cas que nous  confrontons aux données de la littérature. Observation: Un homme âgé de 43 ans, présentait une inflammation conjonctivale de l’oeil gauche évoluant depuis 14 mois, avec apparition progressive d’une exophtalmie axile irréductible et indolore aggravée d’une ophtalmoplégie et d’une cécité gauche. L’IRM orbitaire a mis en évidence une masse tissulaire retro-oculaire iso intense en T1, hyper signal en T2. L’examen anatomopathologique de la pièce opératoire obtenue par voie fronto-orbitaire gauche a permis de poser le diagnostic de TFS orbitaire. L’évolution est favorable avec un recul d’un an. Discussion: Le diagnostic de TFS est anatomopathologique. Il s’agit d’une tumeur de nature mésenchymateuse. On note une forte expression de l’antigène CD34 et de la vimentine en immunohistochimie. Conclusion: La TFS de l’orbite est une tumeur rare habituellement bénigne. Elle doit être différenciée imunohistochimiquement des autres types mésenchymateuses de l’orbite. Sa prise en charge repose sur l’exérèse chirurgicale complète, et un suivi clinique prolongé est proposé car des récidives peuvent survenir à long terme et il existe des formes malignes

Association of respiratory symptoms and lung function with occupation in the multinational Burden of Obstructive Lung Disease (BOLD) study

Background Chronic obstructive pulmonary disease has been associated with exposures in the workplace. We aimed to assess the association of respiratory symptoms and lung function with occupation in the Burden of Obstructive Lung Disease study. Methods We analysed cross-sectional data from 28 823 adults (≥40 years) in 34 countries. We considered 11 occupations and grouped them by likelihood of exposure to organic dusts, inorganic dusts and fumes. The association of chronic cough, chronic phlegm, wheeze, dyspnoea, forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1)/FVC with occupation was assessed, per study site, using multivariable regression. These estimates were then meta-analysed. Sensitivity analyses explored differences between sexes and gross national income. Results Overall, working in settings with potentially high exposure to dusts or fumes was associated with respiratory symptoms but not lung function differences. The most common occupation was farming. Compared to people not working in any of the 11 considered occupations, those who were farmers for ≥20 years were more likely to have chronic cough (OR 1.52, 95% CI 1.19–1.94), wheeze (OR 1.37, 95% CI 1.16–1.63) and dyspnoea (OR 1.83, 95% CI 1.53–2.20), but not lower FVC (β=0.02 L, 95% CI −0.02–0.06 L) or lower FEV1/FVC (β=0.04%, 95% CI −0.49–0.58%). Some findings differed by sex and gross national income. Conclusion At a population level, the occupational exposures considered in this study do not appear to be major determinants of differences in lung function, although they are associated with more respiratory symptoms. Because not all work settings were included in this study, respiratory surveillance should still be encouraged among high-risk dusty and fume job workers, especially in low- and middle-income countries.publishedVersio