M.S. Zabihi

Nowadays, quasi-continuous wave diode lasers are used in a widespread variety of applications. Temperature effects in these lasers can strongly influence their performance. In this paper, the effects of temperature have been experimentally investigated on different features of a 60W-QCW diode laser. The obtained results indicate that the conversion efficiency and operation voltage of diode laser decrease with the augmentation of the working temperature associated with a redshift in the laser peak wavelength. Experimental results show the emission peak wavelength of laser shifts 0.26 nm and the conversion efficiency decreases 1.76 % with the increase of temperature from 40 to 50 ̊C. Present study also shows the slope efficiency decreases gradually at low temperatures and rapidly at higher temperatures. Regarding the close dependence of the mentioned parameters to the operating temperature, it is of great importance to carefully control the working temperature of diode laser, particul...

Performance of microchannel heatsink (MCHS) partially filled with foam is investigated numerically. The open cell copper foams have the porosity and pore density in the ranges of 60–90% and 60–100 PPI (pore per inch), respectively. The three-dimensional steady, laminar flow, and heat transfer governing equations are solved using finite volume method. The performance of microchannel heatsink is evaluated in terms of overall thermal resistance, pressure drop, and heat transfer coefficient and temperature distribution. It is found that the results of the surface temperature profile are in good agreement with numerical data. The results show the microchannel heatsink with insert foam appears to be good candidates as the next generation of cooling devices for high power electronic devices. The thermal resistance for all cases decreases with the decrease in porosity. The uniformity of temperature in this heatsink is enhanced compared the heatsink with no foam. The thermal resistance versu...

Al206/5vol.%Al2O3p cast composites were fabricated by the injection of reinforcing particles into molten Al alloy in two different forms, i.e. as Al2O3 particles and milled particulates of alumina with Al and Mg powders. The resultant milled powders (Master Metal Matrix Composite (MMMC)) were then added into the molten Al alloy both in semi-solid state and above liquidus temperature. Effects of powder addition technique, reinforcement particle size and casting temperature on distribution and incorporation of reinforcing particles into molten Al alloy were investigated. Morphology evolution of powders during milling, microscopic examinations of composite and matrix alloy were studied by scanning electron microscopy (SEM). X-ray diffraction (XRD) analysis was also used to determine the possible interaction between powders after ball milling process. Results showed that injection of powders in the form of MMMC leads to considerable improvement in incorporation and distribution of Al2O3...

The tilt angle influences the amount of energy collected by a photovoltaic module. However, representations of these effects on the energy yield and the performance of the PV system are commonly based on the theoretical calculations, whereas there is a lack of ...

The application of PV systems in Iran has started since 1982, when a 1710 Watt power generator was installed in Fars (south east of Iran) to supply a telecommunication site by AEG. Till 1993 more than one hundred PV systems with various capacity and purpose of use have been installed over the country. In 1993 a production line for multicrystalline