| dc.description.abstract | An ultrasonic car braking system includes an ultrasonic wave emitter provided in a
front portion of an automatic braking car producing and emitting ultrasonic waves
frontward in a predetermined distance in front of the car. Ultrasonic receiver also
formed in a front portion of the car operatively receiving a reflective ultrasonic
wave signal as reflected by obstacles positioned within the pre-determined distance
in front of the automatic braking car. The reflected wave (detection pulse) was
measured to get the distance between the vehicle and the obstacle.
Most internal combustion engines are water cooled or a liquid coolant run through
a heat exchanger (radiator) cooled by air. In air cooling system, heat is carried
away by the air flowing over and around the cylinder. Here fins are cast on the
cylinder head and cylinder barrel which provide additional conductive and
radiating surface. In water-cooling system of cooling engines, the cylinder walls
and heads are provided with jacket through which the cooling liquid can circulate.
An internal combustion engine produces power by burning fuel within the
cylinders; therefore, it is often referred to as a "heat engine." However, only
about25% of the heat is converted to useful power. What happens to the remaining
75 percent? Thirty to thirty-five percent of the heat produced in the combustion
chambers by the burning fuel is dissipated by the cooling system along with the
lubrication and fuel systems. Forty to forty- five percent of the heat produced
passes out with the exhaust gases. If this heat were not removed quickly,
overheating and extensive damage would result. Valves would burn and warp,
lubricating oil would break down, pistons and bearing would overheat and seize,
and the engine would soon stop. The necessity for cooling may be emphasized by
considering the total heat developed by an ordinary six-cylinder engine | en_US |
