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A Loop Thermosyphon has been designed, fabricated and tested to investigate the heat transfer characteristics by two-phase natural convection. The rig was made from copper tubes connected with each other in closed loop including four main parts: vertical evaporator located in the bottom of the device and surrounded by an electrical coil heater as a heat source ,a horizontal condenser located in the upper part of the device cooled by water, vapor rising adiabatic tube and condensate return adiabatic tube. In this research the effect of heat input and filling ratio of the evaporator on the heat transfer coefficient and temperature distribution on the loop surface was verified experimentally using distilled water as working fluid at operating pressure near-atmospheric pressure. The maximum heat transport capability for evaporator was found to be equal to (3424 W/m2 °C). A comparison between the present work results with empirical and theoretical correlations of other researchers showed good agreement. [ABSTRACT FROM AUTHOR]

This work deals with investigating of d.c. motor speed controlled by a buck-boost converter. Open loop system is tested. Aneuro-Fuzzy controller with random number and type of membership function is designed to control the speed of the d.c. motor as a closed loop system. Because of the lack of a clear and a known way for selecting the type and number of membership function in case of fuzzy control, An Adaptive Neuro-Fuzzy Inference System which comprises a fuzzy inference structure and neural network learning ability is modified to control the speed of the motor. The technique is used to select the optimal number and the best type of membership function for the fuzzy system. The process is carried out through testing four types of membership functions with different numbers (3,5,...etc) for each type and computing the absolute error for each case comparing their results to choose the smallest among them. Then the chosen root is applied to control the system for the rest time of control. The technique is applied to two loads (motors). [ABSTRACT FROM AUTHOR]