18WuD2x

468 natural-growth curve • near infrared
natural-growth curve See EXPONENTIAL IN-
CREASE.
natural interference Interference from atmospheric
and celestial sources, as opposed to human-made
interference.
natural language A spoken or written human language
(such as French or Japanese), as opposed
to a computer language (such as machine language,
C++, or LISP). Translation between natural
language and machine language is important
in optical character recognition, speech recognition,
and speech synthesis.
natural logarithm See NAPIERIAN LOGARITHM.
natural magnet A material, such as magnetite
(lodestone), found in nature and exhibiting permanent
magnetism.
natural magnetism Magnetism found in some
natural materials (see NATURAL MAGNET) and in
the earth itself.
natural number 1. Any nonnegative whole number,
that is, a member of the set N = (0, 1, 2, 3, . . .).
2. See NAPIERIAN BASE.
natural period The time required for one complete
wave cycle to occur in a device at its NATURAL
RESONANT FREQUENCY.
natural radiation Noise in the form of radiation
emitted by natural radioactive substances, cosmic
rays, etc. Also called BACKGROUND RADIATION.
natural resonance Resonance resulting from the
unique physical constants of a body, circuit, or
system. Also see NATURAL RESONANT FRE-
QUENCY.
natural resonant frequency 1. The frequency at
which a circuit or device responds with maximum
amplitude to applied signals. 2. The frequency at
which a circuit or device generates maximum energy.
3. The frequency at which an object vibrates
at maximum amplitude.
natural wavelength The wavelength corresponding
to the NATURAL RESONANT FREQUENCY of
a circuit, device, or object.
nautical mile A nautical unit of linear measure
equal to 1.852 kilometers (1.1508 statute miles).
nav 1. Abbreviation of navigation. 2. Abbreviation
of navigational.
Navaglobe A radionavigation system used at verylow
or low frequencies over long distances.
NAVAIDS Abbreviation of NAVIGATIONAL AIDS.
navar A radar system in which a ground radar
scans the immediate vicinity of an airport, observes
the flight activity, and transmits such observations
to aircraft in flight. The name is a
contraction of the term navigation and ranging.
navigation aid An electronic device or system,
such as radar or radio direction finding, that assists
in the navigation of vehicles on land, at sea,
or in the air.
navigation beacon A beam that provides aircraft
and ships with navigational aid.
NAWAS Abbreviation of National Attack Warning
System.
Nb Symbol for NIOBIUM.
nb Abbreviation of NARROWBAND.
NBFM Abbreviation of NARROWBAND FRE-
QUENCY MODULATION. Also abbreviated NFM.
NBS Abbreviation for NATIONAL BUREAU OF
STANDARDS.
NBTDR Abbreviation of narrowband time-domain
reflectometry.
nbw Abbreviation of NOISE BANDWIDTH.
NC 1. Abbreviation of NORMALLY CLOSED. 2. On
drawings, abbreviation of no connection. 3. Abbreviation
of NUMERICAL CONTROL.
N/C Abbreviation of NUMERICAL CONTROL.
nc Abbreviation of no connection.
n-channel junction field-effect transistor Abbreviation,
NFET. A junction field-effect transistor in
which the gate junction is formed on a bar or die
of n-type semiconductor material.
Source
n
Gate
p
p
n-channel junction field-effect transistor
Drain
n-channel MOSFET A metal-oxide-semiconductor
(MOS) field-effect transistor in which the channel
is n-type material.
NCMT Abbreviation of NUMERICALLY CONTROL-
LED MACHINE TOOL.
NCS Abbreviation of net control station(s).
N curve A negative-resistance voltage-current
curve having a shape roughly resembling an uppercase
letter N. Compare S CURVE.
Nd Symbol for NEODYMIUM.
N display A radar display in which the target is
represented by a pair of vertical blips, whose amplitude
indicates target direction and whose position
along the horizontal base line (as determined
by lining up a pedestal signal with the blips) is
read from the pedestal-adjustment calibration.
n-doped zinc-oxide ceramic A nonlinearresistance
material used in the manufacture of
some voltage-dependent resistors.
NDR Abbreviation of NONDESTRUCTIVE READ.
NDT Abbreviation of NONDESTRUCTIVE TEST.
Ne Symbol for NEON.
near-end crosstalk Crosstalk originating at, or
near, the telephone subscriber line in which the
interference is noticed.
near field 1. The radiation field within a radius of
1 wavelength from a transmitting antenna. 2. The
sound field near a loudspeaker or other reproducer.
near infrared Pertaining to electromagnetic radiation
of 3 to 30 micrometers in wavelength.