The total efficiency, $${\eta _t}$$ for a finned surface may be defined as the ratio of the total heat transferred by the combined area of the fins, $${A_r},$$ and the exposed surface to that by the total area, $$A$$, if it were maintained at the base temp, $${T_0}.$$ Assuming uniform heat transfer coefficient over the entire surface, derive an expression for the relationship between efficiency and effectiveness of the fin.

In an ideal inventory control system, the economic lot size for a part is $$1000.$$ If the annual demand for the part is doubled, the new economic lot size required will be:

Which of the following is a technique for forecasting?

In order to test the efficiency of reducer gear train $$1kW$$ input was given at the input end at a speed of $$1440$$ $$rpm$$ and at the output end the measured torque was $$56.36$$ $$N.m.$$ If the ratio of speed reduction in this unit is $$10:1,$$ the efficiency is about