A maximum power point tracking of a photovoltaic system connected to a three-phase grid using a variable step size perturb and observe algorithm

Purpose. The production of electricity from solar energy is necessary because of the global consumption of this energy. This article’s study is based on increased energy extraction by improving maximum power point tracking (MPPT). From different MPPT techniques proposed, the perturb and observe (P&O) technique is developed because of its low implementation cost and ease of implementation. Methods. A modified variable step-size P&O MPPT algorithm is investigated which uses fuzzy logic to automatically adjust step-size to better track maximum power point, compared with the conventional fixed step-size method. The variable step P&O improves the speed and the tracking accuracy. This controller is implemented on a boost DC-DC power converter to track the maximum power point. The suggested controlled solar energy system includes a boost converter, a voltage-source inverter, and a grid filter. The control scheme of a three-phase current-controlled pulse-width modulation inverter in rotating synchronous coordinate d-q with the proposed MPPT algorithm and feed-forward compensation is studied. Results. The photovoltaic grid-connected system controller employs multi-loop control with the filter inductor current of the inverter in the inner loop to achieve a fast dynamic response and the outer loop to control bus voltage for MPPT, the modeling, and control of three phase grid connected to photovoltaic generator is implemented in the MATLAB/Simulink environment and validated by simulation results.Мета. Виробництво електроенергії із сонячної енергії необхідне через глобальне споживання цієї енергії. Дослідження цієї статті ґрунтується на збільшенні вилучення енергії за рахунок покращення відстеження точки максимальної потужності (MPPT). З різних запропонованих методів MPPT був розроблений метод збурення та спостереження (P&O) через його низьку вартість реалізації та простоту реалізації. Методи. Досліджується модифікований алгоритм P&O MPPT зі змінним розміром кроку, який використовує нечітку логіку для автоматичного налаштування розміру кроку для кращого відстеження точки максимальної потужності порівняно із звичайним методом фіксованого розміру кроку. Змінний крок P&O підвищує швидкість та точність відстеження. Цей контролер реалізований на перетворювачі, що підвищує потужності постійного струму для відстеження точки максимальної потужності. Пропонована керована сонячна енергетична система включає підвищуючий перетворювач, інвертор джерела напруги і мережевий фільтр. Досліджується схема управління трифазним струмокерованим інвертором з широтно-імпульсною модуляцією в синхронній координаті, що обертається, d-q із запропонованим алгоритмом MPPT і попереджувальною компенсацією. Результати. Контролер фотоелектричної системи, підключеної до мережі, використовує багатоконтурне керування зі струмом індуктора фільтра інвертора у внутрішньому контурі для досягнення швидкого динамічного відгуку та зовнішнім контуром для керування напругою шини для MPPT, моделювання та керування трифазною мережею. підключений до фотогальванічного генератора, реалізований у середовищі MATLAB/Simulink та підтверджений результатами моделювання

Trends in Secondary Prevention of Coronary Heart Disease in Tunisia: Prevention of Recurrences of MI and Stroke

ObjectivesThe survival benefits achieved by prescription of antiplatelet agents, B-adrenoreceptor antagonists (beta-blockers), angiotensin II receptor blockers (ARB), and lipid lowering agents in patients surviving the myocardial infarction (MI) have been well documented in large clinical trial. Despite well-established benefits, these pharmacological agents continue to be underutilized. The main objective of this study was to evaluate the progress of cardiovascular secondary prevention practices in Tunisia.MethodsThe PREMISE (Prevention of Recurrence of Myocardial Infarction and Stroke) is a descriptive, cross-sectional study conducted in Tunisia in two phases (2002 and 2009). Seven hundred eighty two patients were recruited. The recruitment criteria were: previous MI, stable angina, unstable angina, percutaneous transluminal coronary angioplasty (PTCA), coronary artery bypass graft (CABG), stroke, transient ischemic attack (TIA) or carotid endarterectomy. This analysis is limited to coronary heart disease (CHD) patients. Five hundred hospital patients were interviewed and their medical records were reviewed: 250 in 2002 and 250 in 2009. Patients were included if they had confirmed diagnosis of MI, angina, CABG or PTCA, and if their first cardiovascular event had occurred more than one month but not later than 3 years ago. We compared the total of both patient groups, using the prevalence of Cardio-Vascular Risk Factors (CVRF) and the treatment prescribed at hospital discharge.ResultsThe proportion of patients with reported hypertension, diabetes, hypercholesterolemia and current smoker patients had decreased. Concerning pharmacological prescriptions, a significant increase was observed in prescribing statins (38.9% vs. 70.3%) and ACE inhibitors (49.3% vs. 69.9%), non pharmacological prescriptions as healthy diet or tobacco cessation had opposite trends. Adherence to treatment did not change substantially.ConclusionAlthough the use of cardioprotective drugs had increased in CHD patients, there are still gaps in secondary prevention in Tunisia. The recommended strategies of secondary prevention need to be applied more intensively in clinical practice

Experimental and numerical study of crack healing in a nuclear glass

International audiencea b s t r a c t An experimental study of thermally or water-induced crack healing in an inactive borosil-icate glass, chemically analogous to that used in France for the vitrification of nuclear waste was carried out. Partial welding of glass plates was observed after annealing in air at 425 °C (77 °C below T g) when at least 20 MPa compressive stress was applied, while annealing at 450 °C under 20 MPa led to a complete disappearance of the interface. Closure of indenta-tion-induced cracks was observed during annealing at 400 °C in an ESEM as a result of viscous relaxation of residual stresses but it did not constitute a sufficient proof of crack healing. DCDC specimens were thus pre-cracked in an ESEM and then either annealed at various temperatures (350–490 °C) in secondary vacuum or in air, or left in water at 70–90 °C, sometimes under a compressive stress normal to the crack face. The specimens were then reloaded in the ESEM and the crack opening displacements under a given load were compared to those measured during pre-cracking. The cracks were bridged by an alteration layer over a distance from the crack tip which decreased as loading increased. The restraining effect of these bridges on crack opening was assessed via finite element simulations, using interface elements. The tensile strength of the bridging layer was estimated as 27–39 MPa after vacuum annealing at 400 °C, 11–20 MPa after 15 days in water at 90 °C and 44–78 MPa after 11 days in water at 70 °C under 5 MPa normal compression. Partially healed cracks did not resume propagation from their former crack tip, but due to branch cracks re-initiated a few hundred microns behind it which grow avoiding the healed area. This behaviour was explained using finite element simulations

Parametrization of the Relativistic (σ−ω\sigma-\omega) Model for Nuclear Matter

We have investigated the zero-temperature equation of state (EoS) for infinite nuclear matter within the $(\sigma-\omega)$ model at all densities $n_{\mathrm{B}}$ and different proton-neutron asymmetry $\eta\equiv(N-Z)/A$. We have presented an analytical expression for the compression modulus and found that nuclear matter ceases to saturate at $\eta$ slightly larger than $0.8$. Afterward, we have developed an analytical method to determine the strong coupling constants from the EoS for isospin symmetric nuclear matter, which allow us to reproduce all the saturation properties with high accuracy. For various values of the nucleon effective mass and the compression modulus, we have found that the quartic self-coupling constant $G_4$ is negative, or positive and very large. Furthermore, we have demonstrated that it is possible (a) to investigate the EoS in terms of $n_{\mathrm{B}}$ and $\eta$; and (b) to reproduce all the known saturation properties without $G_4$. We have thus concluded that the latter is not necessary in the $(\sigma-\omega)$ model.Comment: 15pp; article published online: August 06, 2010 by Phys. Rev.

Menopause and metabolic syndrome in Tunisian women

Objectives. This study aimed to evaluate the effect of menopausal status on the risk of metabolic syndrome (MetS) in Tunisian women. Methods. We analyzed a total of 2680 women aged between 35 and 70 years. Blood pressure, anthropometric indices, fasting glucose, and lipid profile were measured. The MetS was assessed by the modified NCEP-ATPIII definition. Results. The mean values of waist circumference, blood pressure, plasma lipids, and fasting glucose were significantly higher in postmenopausal than in premenopausal women, a difference that was no longer present when adjusting for age. Except for hypertriglyceridaemia, the frequency of central obesity, hyperglycemia, high blood pressure, and high total cholesterol was significantly higher in postmenopausal than in premenopausal women. After adjusting for age, the significance persisted only for hyperglycemia. The overall prevalence of MetS was 35.9%, higher in postmenopausal (45.7% versus 25.6%) than in premenopausal women. A binary logistic regression analysis showed that menopause was independently associated with MetS (OR = 1.41, 95% CI 1.10-1.82) after adjusting for age, residence area, marital status, family history of cardiovascular disease, education level, and occupation. Conclusions. The present study provides evidence that the MetS is highly prevalent in this group of women. Menopause can be a predictor of MetS independent of age in Tunisian women

Angiofibrome Nasopharyngien Compliqué D\'un Syndrome De Foster Kennedy : Place De La Chimiothérapie

L\'angiofibrome nasopharyngien (FNP) est une tumeur vasculaire bénigne localement agressive. Il représente 0,05% des tumeurs de la tête et du cou et touche presque exclusivement les adolescents de sexe masculin. La chirurgie est considérée comme le traitement principal du FNP, les autres modalités thérapeutiques tels que radiothérapie et chimiothérapie sont indiquées en cas d\'extension intracrânienne avec envahissement du sinus caverneux ou de la carotide interne. Nous rapportons une observation rare de FNP, compliqué d\'un syndrome de Foster Kennedy chez une femme de 34 ans. Le traitement a consisté en une chimiothérapie (adriamycine, décarbazine) suivie d\'une radiothérapie. Nous discutons de l\'intérêt et des résultats de la chimiothérapie dans le traitement des FNP avec une importante extension intracrânienne (stade III B de la classification de Radkowski).Nasopharyngeal angiofibroma is a locally aggressive, although histologically benign, vascular neoplasm. This neoplasm accounts for 0.05% of the head and neck tumours and affects almost exclusively male adolescents. Surgery is considered as the primary treatment of nasopharyngeal angiofibroma. Other treatment modalities such as radiotherapy and chemotherapy are still recommended for intracranial extension involving the cavernous sinus or the internal carotid artery. We report a rare case of nasopharyngeal angiofibroma, further complicated with a Foster Kennedy syndrome in a 34- years-old woman. The treatment consisted in a chemotherapy (adriamycine, decarbazine) followed by radiotherapy. We discuss the relevance and the outcome of chemotherapy in the treatment of the nasopharyngeal angiofibromas with a consistent intracranial extension (stage III B of Radkowski\'s classification). Journal Tunisien d\'ORL et de chirurgie cervico-faciale Vol. 16 2006: pp. 46-4

Lagranulomatose De Wegener Apropos De Trois Localisations Orl Rares

La granulomatose de Wegener (GW) est une vascularite nécrosante granulomateuse présentant un tropisme particulier pour les voies aériennes supérieures. Nous rapportons 3 cas de la GW correspondants à des localisations ORL rares de la maladie : orbito-meningée, laryngée et linguale. Le but de nos études est d\'analyser les particularités épidemiologiques et cliniques de cette pathologie.Wegener\'s Granulomatosis (WG) is a necrotizing granulomatous vasculitis that has a strong affinity for the upper respiratory tract. We report 3cases of rare ORL locations of Wegener\'s Granulomatosis (orbit, larynx and tongue). The aim of our study is to analyse the characteristic features of WG. Journal Tunisien d\'ORL et de chirurgie cervico-faciale Vol. 16 2006: pp. 26-2

Radionescrose cerebrale a propos d\'une observation

No Abstract. Journal Tunisien d\'ORL et de chirurgie cervico-faciale Vol. 17 2006: pp. 55-5

22q11 Deletion Syndrome and Urogenital Manifestations: A Clinicopathological Case Report.

Deletion in the chromosomal region 22q11 results from the abnormal development of the third and fourth pharyngeal pouches during embryonic life and presents an expansive phenotype with more than 180 clinical features described that involve every organ and system. A 23-year-old African woman presented for the first trimester echography, which revealed an isolated anechoic structure suggesting a ureteral dilatation. The suspicion of a malposition of great arteries in the second trimester indicated an amniocentesis leading to a diagnosis of 22q11 deletion. At 32 weeks, the patient was admitted for premature rupture of membranes and gave birth 2 weeks later to a male newborn who presented a respiratory distress syndrome and probably died secondary to a tracheal stenosis. Necropsy revealed typical clinical features of 22q11 deletion associated with left renal agenesis, hypospadias, and penile hypoplasia. We report a case of 22q11 deletion syndrome with typical clinical features associated with urogenital manifestations suspected at the first trimester ultrasound

Reliability, validity, and responsiveness of a smartphone-based manikin to support pain self-reporting

Introduction:Many people worldwide suffer from chronic pain. Improving our knowledge on chronic pain prevalence and management requires methods to collect pain self-reports in large populations. Smartphone-based tools could aid data collection by allowing people to use their own device, but the measurement properties of such tools are largely unknown.Objectives:To assess the reliability, validity, and responsiveness of a smartphone-based manikin to support pain self-reporting.Methods:We recruited people with fibromyalgia, rheumatoid arthritis, and/or osteoarthritis and access to a smartphone and the internet. Data collection included the Global Pain Scale at baseline and follow-up, and 30 daily pain drawings completed on a 2-dimensional, gender-neutral manikin. After deriving participants' pain extent from their manikin drawings, we evaluated convergent and discriminative validity, test-retest reliability, and responsiveness and assessed findings against internationally agreed criteria for good measurement properties.Results:We recruited 131 people; 104 were included in the full sample, submitting 2185 unique pain drawings. Manikin-derived pain extent had excellent test-retest reliability (intraclass correlation coefficient, 0.94), moderate convergent validity (ρ, 0.46), and an ability to distinguish fibromyalgia and osteoarthritis from rheumatoid arthritis (F statistics, 30.41 and 14.36, respectively; P &lt; 0.001). Responsiveness was poor (ρ, 0.2; P, 0.06) and did not meet the respective criterion for good measurement properties.Conclusion:Our findings suggest that smartphone-based manikins can be a reliable and valid method for pain self-reporting, but that further research is warranted to explore, enhance, and confirm the ability of such manikins to detect a change in pain over time.</p