84 research outputs found

    Adaptive backstepping control of induction motor powered by photovoltaic generator

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    This paper is aimed at addressing the design of an effective adaptive nonlinear control of a photovoltaic (PV) water pumping system powering a submersible induction motor and a centrifugal water pump. Four objectives are achieved using an adaptive Backstepping controller. First, it is applied to ensure maximum power point tracking, and uses the latter as a reference in regulation of the rotor speed to convert the maximum electrical power into maximum mechanical power. Second, the adaptive controller is synthesized to control motor rotor flux and restrict the magnetic circuit to its linear interval. Third, it is used to online estimate the rotor time-constant and the load torque disturbance estimation. Finally, this controller is employed to limit the stator currents to protect induction motor windings. Mathematical modelling of the main elements of the system is presented. A sliding mode rotor flux estimator is employed in the output feedback control of the whole system. DC-AC converter is controlled by pulse width modulation. The feasibility, the robustness and the effectiveness of the proposed adaptive nonlinear controller are evaluated through simulations in MATLAB/Simulink environment

    Integral Backstepping Based Nonlinear Control for Maximum Power Point Tracking and Unity Power Factor of a Grid Connected Hybrid Wind-Photovoltaic System

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    This paper proposes a novel integral backstepping-based nonlinear control strategy for a grid-connected wind-photovoltaic hybrid system. Firstly, detailed three-phase models of the hybrid system elements are presented, and then an overall state-space model is derived. Secondly, nonlinear control laws for the hybrid system’s converters are developed with the aim of ensuring maximum extraction of the available renewable energy, stabilizing the DC bus voltage and guaranteeing the operation of the hybrid system at unity power factor. The overall stability of the closed-loop system is demonstrated on the basis of Lyapunov’s stability theory. Comprehensive simulations, using the MATLAB/Simulink software environment, are carried out to assess the effectiveness of the proposed control methodology. The simulation results obtained confirm that the proposed control strategy offers high efficiency in various operating modes of the hybrid generation system

    EFFECT OF A BINARY BLEND COMPOSED OF POLOXAMER AND PVP ON AQUEOUS SOLUBILITY OF GRISEOFULVIN

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    Objective: The aim of this study was to improve the aqueous solubility of a poorly water soluble drug griseofulvin.Methods: To accomplish this goal a technique of solid dispersion with polyvinyl pyrolidone (k30) and poloxamer 407 was used. Solubility of griseofulvin alone and the solid dispersion were performed in 10 ml purified water and measured spectrophotometricaly atλ max 295 nm to detect the coefficient of improvement.Results: Solubility of griseofulvin alone was found to be 0.812 mg and the solubility of solid dispersion ranged from1.64 to 9.56 mg. After generating polynomial models correlating the variables using a D-Optimal mixture design, an optimal formulation with desired response was proposed by the statistical package. For validation, a new solid dispersion formulation based on the optimized composition was prepared and tested for solubility of griseofulvin. The optimized solid dispersion formulation enhances the solubility of griseofulvin by about 12 folds. Increase the amount of poloxamer in the optimized formulation increases the griseofulvin solubility to about 6 folds more than the optimized form.Conclusion: solid dispersion technique in conjunction with statistical design was shown to be very efficient for the optimization and improvement of aqueous solubility of poorly soluble drugs.Â

    Integral Backstepping Control for Maximum Power Point Tracking and Unity Power Factor of a Three Phase Grid Connected Photovoltaic System

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    This paper presents a robust control strategy for a grid connected photovoltaic system with a boost converter by using an integral Backstepping method based on a nonlinear state model, which guarantees the Lyapunov stability of the global system. The system has tracked precisely the maximum power point, with a very fast response and the unit power factor has been observed under different atmospheric conditions. Moreover, the best advantage of the controller is that it’s a good corrector of the grid perturbation and system parameter disturbance. The simulation result has demonstrated the performance of this strategy

    Backstepping based power control of a three-phase Single-stage Grid-connected PV system

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    In order to reduce costs while maintaining superior performance, this paper presents a new control methodology of a three-phase grid connected photovoltaic system without using the intermediary DC/DC converter. Based on the synchronized nonlinear model of the whole photovoltaic system, two controllers have been proposed for the three-phase inverter in order to ensure the operation of the PV system at the maximum power point with unity power factor and minimum grid disturbance. Grid synchronization has been ensured by a three-phase 2nd order PLL (Phase-Locked Loop). The stability of each controller is demonstrated by means of Lyapunov analysis and evaluated under changing atmospheric conditions using the Matlab/Simulink environment, the simulation results clearly demonstrate the performance provided by each controller

    The role of digitization in revitalizing the course system at Northern Technical University

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    Northern Technical university in Iraq relied in their education on the course system, this system was characterized by some kind of difficulties. A questionnaire was distributed to professors, technicians, administrators, and students subject to the curriculum system as a secondary source for collecting data and information. The study found that NTU as a young and modern university has an infrastructure supported by an electronic educational administrative information system, It provides an integrated digital platform for teachers to participate extensively in lectures, courses, scientific and practical workshops, create interactive lessons, create assignments, tests and assessment through a solid and efficient platform that facilitated the student to complete his homework and duties in the time available to him by notifying them and informing them by sending an email that includes educational content and information and communication technology urged the university to continue with the course system. The study dealt with data analysis using structural equation modeling and the confirmatory factor analysis strategy as a means to measure the observational variables represented by the digitization axes, which in turn matched the measures of statistical analysis Amos

    Abstracts from the 3rd International Genomic Medicine Conference (3rd IGMC 2015)

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    Design, Synthesis, and Antimicrobial Activities of 1,2,3-Triazole Glycoside Clickamers

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    Bacterial resistance remains a significant threat and a leading cause of death worldwide, despite massive attempts to control infections. In an effort to develop biologically active antibacterial and antifungal agents, six novel aryl-substituted-1,2,3-triazoles linked to carbohydrate units were synthesized through the Cu(I)-catalyzed azide-alkyne cycloaddition CuAAC of substituted-arylazides with a selection of alkyne-functionalized sugars. The chemical structures of the new derivatives were verified using different spectroscopic techniques. The novel clicked 1,2,3-triazoles were evaluated for in vitro antibacterial activity against Gram-positive Staphylococcus aureus and Gram-negative Pseudomonas aeruginosa, and the obtained results were compared with the activity of the reference antibiotic “Ampicillin”. Likewise, in vitro antifungal activity of the new 1,2,3-triazoles was investigated against Candida albicans and Aspergillus niger using “Nystatin” as a reference drug. The results of the biological evaluation pointed out that Staphylococcus aureus was more susceptible to all of the tested compounds than other examined microbes. In addition, some tested compounds exhibited promising antifungal activity
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