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The proposed method provides a good tracking performance through detecting the variation in the wind speed rapidly. In addition, the implementation does not require prior information on the wind turbine parameters, air density, or wind speed. By investigating the change directions of the mechanical output power of the wind turbine and the rotor speed of the generator, the proposed MPPT algorithm can determine an optimal speed to achieve the maximum power point (MPP).

Then, this optimal speed is set to the reference in the speed control loop to force the system to operate at the MPP. The DC-DC boost converter has been used to boost up the low AC voltage generated by the PMSG directly driven by the wind turbine. The mechanical output power of the wind turbine is calculated from the mechanical torque which is measured directly by sensor.

The proposed scheme is modeled and simulated under SIMULINK/MATLAB. The simulation results are accurate and validate the wind energy conversion system.

Keywords: Wind Turbine, maximum power point tracking (MPPT), permanent magnet synchronous generator (PMSG), wind energy conversion system (WECS).

Abstract

 In recent years, there has been much emphasis and motivation for teaching at schools of different levels to move from the traditional way of teaching “chalk and talk‟ to a more creative and innovative teaching methodology. In this paper, it has been defined the creative thinking and its hidden meaning, also it has explained the creativity as a process which has included four kinds (fluency, flexibility, originality, elaboration). Likewise, it has been mention some barriers that prevent the students of the creative thinking that has divided into three kinds of blocks (perceptual blocks, emotional blocks and cultural blocks). Furthermore, some stimulated strategies and techniques have been explainedd in order to enhance and support using creative thinking of young students. In addition , distinct types of media which have been involved in modern teaching techniques in order to create more creative thoughts which may be helpful in improving the creative thinking of young students. Moreover, some facts about how to prepare for the age of modern teaching technology have offered. Some remarkable examples: encourage students to use different computer programs, electronic mail, databases in their research or ask and answer of their varied questions. The importance of this paper has been embodied in the following: It gives opportunity to influence the personality of teachers to improve their traditional methods of teaching and it is an attempt to change the ministry of education’s policies relating to the current curriculum , in order to move forward more understanding and creative thinking of the information more than memorization.

Thyroid function is impaired by diabetes, resulting into thyroid disorders, accompanied by the alteration of thyroid-stimulating hormone (TSH) and thyroxine (T4) levels. The aim of this study was to investigate the role of vitamin D supplementation on TSH and total T4 levels in serum of Libyan patients suffering from type 2 diabetes mellitus (T2DM) with thyroid disorders. A total of 180 subjects were recruited and distributed into two groups: 80 participants in control group (43 females and 37 males), with an age range of 26-72 years, and 100 participants in T2DM patient group (54 females and 46 males), with an age range of 26-63 years. Each T2DM patient received a monthly intramuscular injection of 200000 ng/ml vitamin D for three months. Glucose, vitamin D, total T4 and TSH levels were determined in serum samples of healthy subjects and of T2DM patients (pre- and post-administration of vitamin D). After the T2DM group received vitamin D supplementation, the mean of vitamin D level increased in the T2DM, while the mean of glucose level decreased. Most importantly, the mean of total T4 level for patients increased significantly (p ˂ 0.05) from 1.34 to 8.23 g/dL, both of which were lower than the control group mean 10.99 g/dL. In contrast, the mean of TSH level for patients decreased significantly (p ˂ 0.05) from 11.77 to 2.71 mU/L, and both values were greater than the control group mean 2.01 mU/L. ANOVA results showed that age, gender, and body mass index had no significant individual interactions (p > 0.05) with vitamin D supplementation on total T4 and TSH levels. Vitamin D supplementation had a beneficial role on total T4 and TSH levels in serum of Libyan T2DM patients with thyroid disorders.

An attempt has been made to evaluate the effect of welding parameters on the weld penetration, weld bead width and heat effective zone of Tungsten Inert Gas (TIG) welded 2 mm 304L stainless steel joints. The welding parameters including arc current, welding travel speed and gas flow rate were used to achieve the optimum joint. Taguchi technique has been implemented to optimize the welding parameters. Orthogonal array L9 (Three factors with three levels 3x3) was used to study the effect of arc current, welding travel speed and gas flow rate on the quality of 304 stainless steel welds. Signal to a noise ratio (SNR) and the analysis of variance (ANOVA) are also used to determine the main effects of different welding parameters on the weld bead width (WB), weld penetration (WP) and heat affected zone (HAZ). Results showed that welding current has significant effect, whereas gas flow rate showed no effect on the quality of 304Lwelded joints. Welding current of 185A, welding speed of 135mm/min and gas flow rate of 15lit/min have been selected as the best process parameter of weld bead width and weld penetration at level three of experiment seven. However, the optimum process parameter for heat affected zone are level one experimental three at165 A, 235 mm/min, 15 lit/min of welding arc current ,travel speed and gas feeding rate, respectively.