In wind turbines, several parameters can affect the productivity of the turbine, such as wind velocity, rotor area, blade aerodynamic design, and blade pitch. In this paper, the effect of various pitch angles for a small wind turbine was investigated. A system of two metal stands with same height is installed (i.e. on the same axis of streaming), the first stand holds an air blower which imitates the wind with constant air blowing. The other, holds a small wind turbine consists of a DC motor and metal hub (steel bush) with 3-blades with equal radial distance (120°). The pitch angle was adjusted at a certain degree of inclination (10°) in which the turbine stars to rotate, then readings of power and rotational speed were collected. The process then repeated with another 3 different angles (15°, 20°, and 25°). At the end, a fixed pitch angle degree was adjusted, and then the lowest and highest air velocity that affecting the blades rotation were measured.

In the current study, we investigate the effect of (La) substitution instead of (Cu) on the properties of the superconductor compound (Bi 2 Sr 2 Ca 2 Cu 3-x La x O 10+δ ) with (x=0,0.05,0.1,0.15,0.2). The samples were prepared by solid state reaction method(SSR). Xray diffraction technique (XRD) was used to estimate the structural properties of the specimens which show an orthorhombic crystalline structure for all the specimens.The results show that the change in ( La) concentration leads to decrease the concentration of (Bi-2223), increment in (Bi-2212 ) and(Bi-2201) with appearance of some impurities. Also decrease the critical temperature(Tc) with the increase of ( La) concentration.

In this paper, the influence of blades number on the performance of pico wind turbine was investigated by using a small-motorized axial DC fan with a rated power of 4W. Fixed streaming air blower was used as a source of wind. Varying in wind speed was accomplished by changing the distance from the blower. A resistor equals to the turbine internal resistance was utilized as a load to collect the electrical power across the load at various wind speeds and for fans of different blades (1, 2, and 5). Values of the cut-in and cut-out speeds were extracted from the power plot. Rated power was recorded, as well. The results have shown that the rated power generated by turbine has decreased due to the reduction of blades number (i.e., reduction in solidity) from 2.6W for a 5-bladed turbine to 0.665W for a 2-bladed turbine and to 0.13W for a 1-bladed turbine. Moreover, the cut-in speed (initial electrical generating speed) has increased from 4.9m/s for 5-bladed to 8m/s for 2-bladed, then to 19.15m/s for 1-bladed. These results are explained by the balancing problems during rotation (polar asymmetrical rotor), and it is seen that the reduction of blades has made a sharp reduction in power coefficient.

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In this paper, a thin film of (Pb2-xSbxBa2Ca2Cu3O10) was deposited on glass substrate using Pulsed Laser Deposition (PLD) method with a power of 400 watts, a frequency of 6 Hz and a rate of 200 pulses. The results showed that the X-ray measurements of the prepared films (crystals). Then, optical and compositional measurements were performed on the films to determine the transmittance and absorption spectrum as a function of the incident wavelength, the value and type of the energy gap. It was found that the energy gap decreases after annealing to become (1.9 eV). As for the structural measurements, the degree of crystallinity and the growth rate of granules and films with direct transfer were calculated. These results are close to those which are obtained previously. The thin films were thermally annealed at 400 °C for two hours. Thermal annealing greatly affects the prepared films, as the annealing improves the properties of the films.