A method and apparatus for removing debris from the propulsion system of a vehicle such as a battle tank, including a tank in which the vehicle is positioned, means for lifting the vehicle in the tank, and means to wash the vehicle’s propulsion system while the vehicle is in raised position. The infrared distance-measuring sensor 2 is provided with a plurality of infrared-ray emitting devices 3-0,. When the oxidized compound is para-xylene and the product from the oxidation reaction is crude terephthalic acid, such CTA product can be purified and separated by more economical techniques than could be employed if the CTA were formed by a conventional high-temperature oxidation process. The thermal absorption properties of the semiconductor wafer are tuned by forming differing patterns in a plurality of the partial die areas. The polygonal shape may be a triangular shape.