A downhole tool for generating power is provided that includes a conductive fluid disposed downhole within a tubular member, an energy harvesting apparatus, and a pressure changing apparatus. The removable fan unit includes a housing and a fan housing rotatably attached to the housing. The AE uses a decaying current pulse generator that generates a decaying current pulse at the beginning of each write-to-read mode transition. A method to assemble furniture having preformed arm, base, seat and back components is provided. An estimate calculation unit calculates the angular velocity estimate on the basis of the detected value of motor voltage, the detected value of motor current and a motor resistance value obtained from the current-resistance characteristic. , the precious metals are leached from the cinder using diluted solution of aqua-regia, and then via sorption.