Three alloys were found to have the hall-petch parameters shown in the following table. alloy σ0 (mpa) ky (mpa mm1/2) a 90 9.2 b 75 6.1 c 170 2.3 which alloy has the highest yield strength for a grain size of 20 microns? which alloy will benefit the most from grain refinement? explain your answer.

Explain the difference laminar and turbulent flow. explain it with the shear stress and the velocity profiles.

What are the two (02) benefits, which may result from a successful implementation of preventive maintenance (pm) program in an organization? (clo3)a)- lean manufacturing b)-overlapping responsibilities c)-the planner is not qualified d)-accurate contractor information e)-reduction in equipment redundancies f)-accurate stores information

Along 8-cm diameter steam pipe whose external surface temperature is 900c connects two buildings. the pipe is exposed to ambient air at 70c with a wind speed of 50 km/hr blowing across the pipe. determine the heat loss from the pipe per unit length. (b) air at 500c enters a section of a rectangular duct (15 cm x 20 cm) at an average velocity of 7 m/s. if the walls of the duct are maintained at 100c. a) the length of the tube for an exit temperature of the air to be 40 0c. b)the rate of heat transfer from the air. c) the fan power needed to overcome the pressure drop in this section of the duct.