时间：2011-03-11 23:13来源：蓝天飞行翻译 作者：admin 点击：次
|
mixture. A combination of substances held together by physical rather than chemical means. The constituents of a mixture retain all their own chemical properties and mixtures do not have to be combined in definite proportions, as is required for chemical compounds. Sweetened tea is a mixture of tea and sugar, and concrete is a mixture of sand, gravel, and cement. mixture control (reciprocating engine control). A control installed in a reciprocating-engine-powered aircraft that allows the pilot to vary the fuel-air mixture ratio while the engine is running. A reciprocating engine requires the proper amount of fuel to be mixed with the air on the basis of the weight of the air. But most fuel-metering systems measure the fuel on the basis of the volume, not the weight, of the air entering the engine. The density (weight per unit volume) of the air decreases as the aircraft goes up in altitude, and the pilot must be able to decrease the amount of fuel metered into the less dense air. This adjustment is made with the mixture control. MLS (microwave landing system). An instrument landing system operating in the microwave spectrum which provides lateral and vertical guidance to aircraft having compatible avionics equipment. MM (middle marker). A marker beacon that defines a point along the glide slope of an instrument landing system (ILS), normally located at or near the point of decision height (ILS Category I). The middle marker is keyed to transmit alternate dots and dashes keyed at the rate of 95 dot-dash combinations per minute, with a 1,300-Hz tone which is received aurally and visually by compatible airborne equipment. MNPS (minimum navigation performance specifications) (air traffic control). A set of standards which require aircraft to have a minimum navigation performance capability in order to operate in MNPS designated airspace. In addition, aircraft must be certified by their State of Registry for MNPS operation. mobile charges (semiconductor materials). Electrical charges that move about within a semiconductor material. Holes are positive mobile charges, and they drift within the material toward a negative electrical charge. Electrons are negative mobile charges, and they drift within the material toward a positive electrical charge. Mobius strip. A one-sided surface twisted in the form of a loop. A Mobius strip, or Mobius loop, is made by taking a long strip of material, holding one end stationary, twisting the other end 180°, and then joining the two ends. MOCA (minimum obstruction clearance altitude) (air traffic control). The lowest published altitude in effect between radio fixes on VOR airways, off-airway routes, or route segments which meets obstacle clearance requirements for the entire route segment and which assures acceptable navigational signal coverage only within 25 statute (22 nautical) miles of a VOR. mock-up. A full-sized imitation of a real device. Mock-ups of complex and costly devices, such as aircraft and space vehicles, are built to assure that all the different systems and components will work properly when they are installed in the actual vehicle. |
