Optimizirano povratnokoračno upravljanje momentom indukcijskog motora korištenjem genetičkog algoritma

This paper proposes a novel hybrid control of induction motor, based on the combination of the direct torque control DTC and the backstepping one, optimized by Genetic Algorithm (GA). First the basic evolution of DTC is explained, where the torque and stator flux are controlled by non linear hysteresis controllers which cause large ripple in motor torque at steady state operation. A Backstepping control is applied to overcome these problems, however the used parameters are often chosen arbitrarily, which may affect the controller quality. To find the best parameters, an optimization technique based on genetic algorithm is used. Also, in order to obtain accurate information about stator flux, torque and load torque, open loops estimators are used for this Backstepping control. At last, experimental results are presented in order to prove the efficiency of the above mentioned control technique.U ovom radu predstavljena je nova metoda hibridnog upravljanja indukcijskim motorom, bazirana na kombinaciji direktnog upravljanja momentom (DCT) i povratnokoračnog upravljanja, te optimizirana korištenjem genetičkog algoritma (GA). Prvo je objašnjena osnova razvoja DCT-a, gdje se momentom i tokom statora upravlja nelinearnim histereznim regulatorima što uzrokuje velike propade u momentu motora tijekom ravnotežnog rada. Povratnokoračno upravljanje se primijenjuje kako bi se uklonio ovaj problem, međutim korišteni parametri su najčešće proizvoljno odabrani što može utjecati na kvalitetu upravljanja. Kako bi se našli najbolji parametri koristi se tehnika optimizacije zasnovana na genetičkom algoritmu. Također kako bi se dobili točni podaci o toku statora, momentu i momentu opterećenja potrebni za povratnokoračno upravljanje koriste se estimatori u otvorenoj petlji. Na kraju su prikazani eksperimentalni rezultati kako bi se dokazala efikasnost navedene metode upravljanja

Activité Acaricide Des Huiles Essentielles Du Mentha Pulegium, Origanum Compactum Et Thymus Capitatus Sur L’acarien Phytophage Tetranychus Urticae Koch (Acari : Tetranychidae)

The use of botanical acaricides extracted from plants as an alternative to replace the chemical acaricides is an interesting and efficient option to control pests and ameliorate their toxic effects to humans and the environment. The aim of this work was to evaluate the contact toxicity of Pennyroyal mint (Mentha pulegium), oregano (Origanum compactum) and thyme (Thymus capitatus) essential oils against adults, larvae and eggs of two-spotted spider mite Tetranychus urticae Koch (Tetranychidae). The chemical composition of these three plant essential oils was also characterized. Laboratory tests were conducted to determine the acaricidal effect of plant essential oils at several doses in geometric progression. The consequences of treatments on mortality were measured in relationships with concentrations of essential oils. On the other hand, the major constituents of the three essential oils were identified by gas chromatography-mass spectrometer (GC-MS) techniques. GCMS analyses proved that the major compound present in the essential oils of thyme and oregano is carvacrol (55.59 and 55.28% respectively) while the main component of pennyroyal mint essential oil is pulegone (67,63%). Laboratory bioassay results indicated that essential oils of thyme and pennyroyal mint caused the most important acaricidal effects in comparison with the essential oil of oregano. At a concentration of 1%, thyme and pennyroyal eradicate all adults of the mite while oregano causes a mortality of 84.99%. On larvae, the mortality rate of thyme, pennyroyal and oregano is 97.7; 89.47 and 57.89% respectively. The results of the present study concluded that plant essential oils could be useful in promoting research aiming at the development of new agent for pest control from the plants with medicinal values

Comportement en flexion de matériaux composites à fibres courtes

Résumé : L'objectif de ce travail est l'analyse du comportement en fatigue d'un composite à matrice en polypropylène et fibres de verre courtes (type E) obtenu par le procédé d'injection. Les courbes de Wöhler sont tracées pour les critères de fin d'essais, N10, N20 Nous avons relevé les mécanismes de dégradation en temps réel lors des essais de fatigue et nous avons essayé de relier ces mécanismes aux interfaces générées par le procédé. Mots clés : Composite, Polypropylène, Statique, Fatigue, Rigidité, Mécanisme

Genetic algorithm optimized robust nonlinear observer for a wind turbine system based on permanent magnet synchronous generator

© 2022 ISA. Published by Elsevier Ltd. All rights reserved. This is the accepted manuscript version of an article which has been published in final form at https://doi.org/10.1016/j.isatra.2022.02.004This paper presents an optimal control scheme for a Permanent Magnet Synchronous Generator (PMSG) coupled to a wind turbine operating without a position sensor. This sensorless scheme includes two observers: The first observer uses the flux to estimate the speed. However, an increase in the temperature or a degradation of the permanent magnet characteristics will result in a demagnetization of the machine causing a drop in the flux. The second observer is therefore used to estimate these changes in the flux from the speed and guaranties the stability of the system. This structure leads to a better exchange of information between the two observers, eliminates the problem of encoder and compensates for the demagnetization problem. To improve the precision of the speed estimator, the gain of the non-linear observer is optimized using Genetic Algorithm (GA) and the speed is obtained from a modified Phase Locked Loop (PLL) method using an optimized Sliding Mode Controller (SMC). Furthermore, to enhance the convergence speed of this observer scheme and improve the performance of the system a Fast Super Twisting Sliding Mode Control (FSTSMC) is introduced to reinforce the SMC strategy. A series of simulations are presented to show the effectiveness and robustness of proposed observer scheme.Peer reviewe

New Hybrid Sensorless Speed of a Non-Salient Pole PMSG Coupled to Wind turbine Using a Modified Switching Algorithm

©2019 ISA. Published by Elsevier Ltd. All rights reserved. his manuscript is made available under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International licence (CC BY-NC-ND 4.0). For further details please see: https://creativecommons.org/licenses/by-nc-nd/4.0/The paper focuses on the design of position and speed observers for the rotor of a non-salient pole permanent magnet synchronous generator (NSPPMSG) coupled to a wind turbine. With the random nature of wind speed this observer is required to provide a position and speed estimates over a wide speed range. The proposed hybrid structure combines two observers and a switching algorithm to select the appropriate observer based on a modified weighting coefficients method. The first observer is a higher-order sliding mode observer (HOSMO) based on modified super twisting algorithm (STA) with correction term and operates in the medium and nominal wind speed ranges. The second observer is used in the low speed range and is based on the rotor flux estimation and the control by injecting a direct reference current different to zero. The stability of each observer has been successfully assessed using an appropriate Lyapunov function. The simulation results obtained show the effectiveness and performance of the proposed observer and control scheme.Peer reviewe

Simulation numérique à trois dimensions d'une flamme de diffusion en utilisant un schéma réactionnel quasi-global et détaillé

Dans le présent travail, on s'intéresse à la simulation numérique en trois dimensions (3D) des flammes de diffusion d'un écoulement turbulent et réactif dans une chambre de combustion d'une turbine à gaz. Un des objectifs est d'étudier l'influence des modèles de combustion et les mécanismes réactionnels sur la prédiction de l'écoulement du champ de température et la modélisation des émissions polluantes NOx. Les résultats numériques obtenus sont comparés aux résultats antérieur

Qualité de la gestion de la formation continue Diagnostic de la situation de l’Administration centrale du MEN au Maroc

Notre article résume les résultats d’une étude empirique ayant porté sur l’état de laqualité de la formation continue dans l’Administration centrale du Ministère de l’EducationNationale (MEN). La collecte des données auprès des responsables hiérarchiques permetde mesurer le degré de qualité sur les différents axes du système de formation continue(FC). Le questionnaire administré recèle des indicateurs qualité dont la mesure permetd’apprécier les pratiques de gestion de la FC. D’après les données collectées, la situationde la FC au MEN laisse à désirer. L’élément phare du mauvais pilotage du système de FCest la violation du principe de participation des bénéficiaires aux différents processus de lagestion de la FC

Research and Toxinogenic Characterization of Penicillium Contaminating Goat's Traditional Dairy Products in Northern Morocco

The goat rearing in northern Morocco had known a very important evolution with the introduction of European breeds of goats more productive of milk compared to local breeds. Moulds are common contaminants in many traditional dairy products. Some species are responsible for significant economic losses and major public health problems by producing toxic metabolites like mycotoxins. This work aims to isolate, identify and characterize the mycotoxin-producing species of Penicillium from milk and traditional cheese (Jben) in the different northern region of Morocco, based on microbiological analysis and in vitro identification of Penicillium toxinogenic by fluorescence detection and HPLC analysis. Our microbiological analysis clearly show that the fungal flora is highly developed in goat's milk and Jben: 85 mould and yeast isolates from 57 samples collected. The rate of fungal flora (mould and yeast species) is high, it is around 2,6 104 CFU/ml in milk and 5,90 104 CFU/g in Jben. Penicillium isolates were purified and identified according to macroscopic and microscopic criteria. The proportion of Penicillium (61,53 %) in milk is more than Jben (16,94 %). The most important Penicillium species in two dairy products are P.italicum (23,1% in milk against 5,1 % in Jben), P. cyclopium (7,7 % in milk against 5,1% in cheese), and P. expansum (7,7% in milk against 3,4 % in cheese). According to in vitro identification of Penicillium toxinogenic by fluorescence detection, the majority of Penicillium isolates were able to produce mycotoxin type Citrinin and Ochratoxin A. The capacity of mycotoxin production by the identified strains was confirmed by High-Performance Liquid Chromatography Analysis. The patulin was produced by all Penicillium isolates, while the citrinin was produced by P. nalgiovense, P. simplicissimum, and P. dipodomyis. Unlike the ochratoxin A was produced by all isolates, except the P. nalgiovense and P. dipodomyis. The presence of toxicogenic Penicillium species in Moroccan traditional goat's dairy products suggeststhat contaminated products according to processing conditions and after storage traditionally could be a risk to the health and safety of consumers. The awareness-raising measures, the professional guidance on the concept of hygienic quality and the tendency to semi-industrial production remain worksites to work more efficiently by the state

Effect of PGPR and mixed cropping on mycorrhizal status, soil fertility, and date palm productivity under organic farming system

A field study was carried out for two years at an organic farm under arid climate in Morocco to investigate the effect of an integrated biofertilization approach on Arbuscular Mycorrhizal Fungal (AMF) abundance and infectivity, soil fertility, yield, and fruit quality of date palm. The biofertilization approach included three management practices namely application of compost, inoculation with a consortium of native PGPR strains originally isolated from date palms of Drâa-Tafilalet region (Pseudomonas koreensis, Serratia nematodiphila, S. marcescens, and Klebsiella sp.) and using mixed-cropping with sorghum. Accordingly, four treatments were established in this study: 1) mixed-cropping with sorghum, 2) PGPR inoculation, 3) sorghum + PGPR, and 4) control (without sorghum or PGPR). All treatments received compost as organic amendment. Results revealed that mixed-cropping with sorghum significantly increased AMF colonization intensity and spore density by more than 50% and 29%, respectively. Sorghum association also resulted in a significant increase in organic matter concentrations of up to 2.95% against 2.45% in monocropping soils. The integrated biofertilization approach resulted in the highest yield with an increase rate of 10.6% and 12.1% in the first and the second year, respectively compared to date palms receiving compost alone. Similarly, the mineral composition and quality characteristics of date fruits were significantly improved. The enhancement of soil fertility and date palm productivity under harsh environmental conditions represents a first step towards the adoption of sustainable practices in the region and in similar areas

Burnout among surgeons before and during the SARS-CoV-2 pandemic: an international survey

Background: SARS-CoV-2 pandemic has had many significant impacts within the surgical realm, and surgeons have been obligated to reconsider almost every aspect of daily clinical practice. Methods: This is a cross-sectional study reported in compliance with the CHERRIES guidelines and conducted through an online platform from June 14th to July 15th, 2020. The primary outcome was the burden of burnout during the pandemic indicated by the validated Shirom-Melamed Burnout Measure. Results: Nine hundred fifty-four surgeons completed the survey. The median length of practice was 10 years; 78.2% included were male with a median age of 37 years old, 39.5% were consultants, 68.9% were general surgeons, and 55.7% were affiliated with an academic institution. Overall, there was a significant increase in the mean burnout score during the pandemic; longer years of practice and older age were significantly associated with less burnout. There were significant reductions in the median number of outpatient visits, operated cases, on-call hours, emergency visits, and research work, so, 48.2% of respondents felt that the training resources were insufficient. The majority (81.3%) of respondents reported that their hospitals were included in the management of COVID-19, 66.5% felt their roles had been minimized; 41% were asked to assist in non-surgical medical practices, and 37.6% of respondents were included in COVID-19 management. Conclusions: There was a significant burnout among trainees. Almost all aspects of clinical and research activities were affected with a significant reduction in the volume of research, outpatient clinic visits, surgical procedures, on-call hours, and emergency cases hindering the training. Trial registration: The study was registered on clicaltrials.gov "NCT04433286" on 16/06/2020