时间：2011-03-11 23:18来源：蓝天飞行翻译 作者：航空 点击：次
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When a pan of water is put on a hot stove, sensible heat enters it until the water reaches a temperature of 100°C (under standard conditions). At this temperature, the water begins to boil, or change its physical state from liquid to gas without increasing its temperature. Heat added to the water after it begins to boil is called latent heat. sensitive altimeter. A form of multipointer pneumatic altimeter with an adjustable barometric scale that allows the reference pressure to be set to any desired level. Sensitive altimeters have a high degree of mechanical amplification in their movement. The small amount of movement of the expanding bellows inside the instrument is multiplied enough to rotate one of the pointers completely around the dial for a pressure change equivalent to only one thousand feet of altitude. This is approximately one inch of mercury. sensitive relay (electrical component). An electromagnetically operated switch whose operating coil requires very little current to close the switch contacts. Sensitive relays are used in photoelectric and thermocouple circuits. The very small current produced by a photocell or thermocouple operates the relay, and the relay contacts control enough current to operate other equipment. Sensitive relays are being replaced today with solid-state devices that do the same job, but have no moving parts. sensitivity (radio receiver specification). A measure of the signal strength needed to produce distortion-free output. The output must not have any excessive noise (unwanted electrical signal) in it, and the output must be electrically identical to the input, except for its higher voltage. A radio receiver with a high sensitivity can produce a usable output from a very weak, or faint, input signal. sensitivity time control (radar technology). A radar circuit designed to correct for range attenuation so the echo intensity on the scope is proportional to reflectivity of the target regardless of range. sensor (automated equipment). The component in a piece of automated equipment affected by some physical condition. The sensor sends signals into the equipment so it will operate in the correct manner. An automatic cowl flap actuation system has a temperature sensor affected by the cylinder head temperature. This sensor sends signals to the cowl flap motor. If the cylinder head temperature is too low, the motor closes the cowl flaps, and if the temperature is too high, the motor opens them. A photoelectric cell is a form of sensor. It is affected by the amount of light or by the color of the light. separation (air traffic control). The spacing of aircraft to achieve their safe and orderly movement in flight and while landing and taking off. sequence valve (fluid power system component). A type of flow control valve that allows one system to fully operate before another system begins its operation. Sequence valves are used in aircraft hydraulic systems to cause the wheel well doors to open fully before the landing gear is released from its uplocks. |
