A simple maximum power point tracking based control strategy applied to a variable speed squirrel cage induction generator

This paper presents a comprehensive modelling and control study of a variable speed wind energy conversion system based on a squirrel-cage induction generator (SCIG). The mathematical model of the SCIG is derived in Park frame along with the indirect field oriented control (IFOC) scheme based on a proportional and integral speed controller. A simple maximum power point tracking strategy is used to determine the optimal speed under variable wind speed conditions which is then used as the reference in the IFOC scheme. Power flow between the supply and the inverter is regulated via simultaneous control of the active and reactive currents of the grid and the DC link voltage. The simulation results show that the proposed control technique is able to maximise the energy extracted from the wind during the simulation scenarios considered. The results also demonstrate good transient response characteristics in the decoupled real and reactive powers.Peer reviewedFinal Accepted Versio

On the Suitability of some English Equivalents to Arabic Culturally-Bound Terms

In a broader sense bilingual dictionaries are viewed to provide translators with all the needed information in the foreign language through the equivalents chosen by the compilers Needless to say that this statement is correct at a certain level mainly when it comes to simple words that do not represent much difficulty for both source language receptors and target language receptors But the matter becomes questionable when the translator deals with cultural-bound words in the frame of the law as a specialized field That is why attention must be paid to such valuable references to pave the way to the translator to transmit the message accurately This study aims to investigate the exactness of English equivalents of some Arabic culture-bound terms in a Legal bilingual dictionary Arabic- English about their original significance in the source culture of each language to draw a comparison between both meanings and the cultural dimensions they reflect The results showed a certain inadequacy between the Arabic word and its equivalent in the majority of the cases especially regarding its ethnographic value which represents its most important aspec

Power Quality Enhancement in Electricity Grids with Wind Energy Using Multicell Converters and Energy Storage

In recent years, the wind power industry is experiencing a rapid growth and more wind farms with larger size wind turbines are being connected to the power system. While this contributes to the overall security of electricity supply, large-scale deployment of wind energy into the grid also presents many technical challenges. Most of these challenges are one way or another, related to the variability and intermittent nature of wind and affect the power quality of the distribution grid. Power quality relates to factors that cause variations in the voltage level and frequency as well as distortion in the voltage and current waveforms due to wind variability which produces both harmonics and inter-harmonics. The main motivation behind work is to propose a new topology of the static AC/DC/AC multicell converter to improve the power quality in grid-connected wind energy conversion systems. Serial switching cells have the ability to achieve a high power with lower-size components and improve the voltage waveforms at the input and output of the converter by increasing the number of cells. Furthermore, a battery energy storage system is included and a power management strategy is designed to ensure the continuity of power supply and consequently the autonomy of the proposed system. The simulation results are presented for a 149.2 kW wind turbine induction generator system and the results obtained demonstrate the reduced harmonics, improved transient response, and reference tracking of the voltage output of the wind energy conversion system.Peer reviewedFinal Accepted Versio

BAYESIAN PREDICTION IN CLINICAL TRIALS DESIGN

The aim of an exploratory clinical trial is to determine whether a new intervention is promising for further testing in confirmatory clinical trials. Most exploratory clinical trials are designed as single-arm trials using a binary outcome with or without interim monitoring for early stopping. In this paper, we are particularly interested in using the predictive Bayesian approach in clinical trials or objectives is the development of important evidence of an effect of interest we offer the procedure based on the notion satisfaction Index is based on the value of p and we are first given the data available to calculate a forecast of future satisfaction data as Bayesian predictive expect this index conditional on past observations. To illustrate the proposed procedure, we proposed the binomial model

Behavior of a gravel-sand material on cyclic way

Cet article présente les résultats des essais triaxiaux cycliques pour étudier le potentiel de liquéfaction d’un matériau sablo-graveleux. De nombreux articles sont consacrés aux essais sur le sable de laboratoire type Hostun notamment pour l’étude de la liquéfaction ou sur des argiles reconstituées mais peu d’essais sont effectués sur un matériau naturel. La rareté des essais cycliques sur les matériaux naturels notamment grossiers, montre la difficulté  d’évaluer le risque sismique. Devant ces difficultés, l’utilisation des essais comme le CPT permet une approche différente mais très pratique. L’ensemble des résultats montre une tendance à la liquéfaction relativement importante du matériau, même dans des conditions de sollicitation modérées (qc/2s’3 = 0.2). Cette tendance s’accroît très fortement quand le taux de sollicitation cyclique atteint 0.3. L’essai au CPT montre également une grande tendance à la liquéfaction avec un coefficient de sécurité largement inférieure à 1. This article has the results of the cyclic triaxial compression tests to study the potential of liquefaction of a gravel-sand material.  The last part is devoted to the not drained cyclic tests and their analyses.  Many articles are devoted to the tests on the standard sand of laboratory Hostun in particular for the study of liquefaction or on reconstituted clays but few tests are carried out on a natural material.  The scarcity of cyclic tests on such rough natural materials shows the difficulty of assessing the seismic risk. Faced with these difficulties, the use of tests such as the CPT provides a different but very practical approach. The overall results show a trend of relatively high liquefaction of the material, even under conditions of moderate stress (qc / 2s'3 = 0.2). This trend is growing very strongly when the rate of cyclic loading reached 0.3. The CPT test also shows a great tendency to liquefaction with a safety factor of well below 1.