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expression separated by a plus or a minus sign are called the terms of the expression.
An algebraic expression having only one term is called a monomial, and one with two or more
terms is called a polynomial.
The algebraic expressions AB, 2Y, and 6X2 are monomials. The expression AB + 2Y - 6X2 is a
polynomial. It is actually a trinomial, because it has three terms.
algorithm. A systematic set of rules or processes by which a problem can be solved in a specific number of
individual steps.
alignment (electronic). The adjustment of the components in an electronic circuit so they will be resonant
at the required frequency.
alignment. The arrangement, or position, of parts of an object or system in correct relationship to each
other.
alignment pin. A pin installed in a helicopter rotor blade to serve as an index when aligning the blades of a
semirigid rotor system.
alignment tool (electronic tool). A nonmetallic screwdriver or socket wrench used to adjust trimmer and
padder capacitors to align the circuits in a piece of electronic equipment.
aliphatic naphtha. A petroleum product similar to gasoline and kerosine. Aliphatic naphtha is used as a
cleaning agent to remove grease from a surface prior to painting.
alkali. A chemical substance, usually the hydroxide of a metal. An alkali has a characteristically bitter taste
and is prone to react with an acid, furnishing the electrons to form a salt.
alkaline. Having the property of reacting with an acid to form a salt by give up electrons to the acidic
material.
alkaline cell. A type of primary electrochemical cell that uses powdered zinc as the anode, powdered
graphite and manganese dioxide as the cathode, and potassium hydroxide as the electrolyte.
An alkaline cell has an open-circuit voltage of 1.5 volts, and it has from 50% to 100% more
capacity than a carbon-zinc cell of comparable size.
Printed from Summit Aviation's Computerized Aviation Reference Library, 2/7/2007
Page 27
alkyd resin. A type of synthetic resin used as the base for certain enamels and primers.
Allen screw. A screw with a hexagonal hole, or socket, in its head.
Allen wrench. A hexagonal rod used to turn an Allen screw. The most common Allen wrenches are bent
with a 90° angle so they have a short and a long leg.
alligator clip. A spring-type clip used on the end of an electrical wire to make temporary connections in an
electrical circuit. An alligator clip has long, narrow, spring-loaded jaws with meshing teeth.
allowable. Permissible.
allowance. The difference between the nominal dimension of a part and its upper or lower limit.
alloy. A physical mixture of chemical elements combined with a metal to change its characteristics.
alloying agent. A chemical element mixed with a base metal to form an alloy. The alloying agents change
the characteristics of the base metal.
alloy steel. Steel into which certain chemical elements have been mixed. Alloy steel has different
characteristics from those of simple carbon steel.
all-weather spark plug. A type of shielded spark plug for use in an aircraft reciprocating engine for
high-altitude operation. The ceramic insulator is recessed into the shell to allow a resilient grommet on the
ignition harness lead to provide a watertight seal.
All-weather spark plugs, also called high-altitude spark plugs, are identified by their 3/4-20
shielding threads.
Alnico. The registered trade name for an alloy of iron, aluminum, nickel, and cobalt. Alnico, which has an
extremely high permeability and excellent retentivity, is used in the manufacture of permanent magnets.
ALNOT (Alert Notice). A message sent by a Flight Service Station or Air Route Traffic Control Center
that requests an extensive communications search for an overdue, unreported, or missing aircraft.
Alodine. The registered trade name for a conversion-coating chemical which forms a hard, unbroken oxide
film on a piece of aluminum alloy. The oxide film produced by Alodine serves the same function as the
film produced by anodizing, but does not require an electrolytic bath. Alodine conforms to specifications
MIL-C-5541B.
Alodizing. A method of corrosion protection by the formation of a hard, airtight oxide coating on the
surface of aluminum alloy parts by chemical means. The name is taken from the registered trade name of
the chemical Alodine.
alpha (transistor operation). A measure of emitter-to-collector current gain of a transistor in a
common-base amplifier circuit. Alpha of a junction transistor is never greater than one. Its output is always
less than its input.
alpha control range, or alpha mode (turboprop operation). The flight operating mode for a turboprop
engine from takeoff through landing.
Alpha mode includes operations from 95% to 100% of the engine’s rated RPM.
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航空术语词典Dictionary of Aeronautical Terms 上(19)
