Page 190 - Electrical Engineering Dictionary

2 sum of the message bits is calculated after cylindrical extension of a fuzzy set let A
i
grouping them in a special way and then ap- beafuzzysetinaCartesianproductspace X ,
n
pended to the transmitted message and used and X be another Cartesian product space
i
by the receiver to determine if the message including X , then the cylindrical extension
n
n
was received correctly. The number of bits of A in X is a fuzzy set in X , denoted as
n
used in the CRC-sum is typically 8 or 16, de- cext(A; X ), with membership function de-
i
pending on the length of the message and the fined equal to membership in X . See also
desired error-detection capability. fuzzy set, membership function, projection
A value calculated from a block of data to of a fuzzy set.
be stored or transmitted with the data block
cylindrical lens a lens that has curvature,
as a check item. CRCs are generated using a
or optical focusing power, in one direction
shift register with feedback and are described
by the length of the register and the feedback only.
terms used.
cylindrical microstrip line structure that
(2) a coding scheme for detecting errors
consists of an angular strip on a cylindrical
in messages. Given a polynomial C(x) of
ground plane separated by a dielectric sub-
order c −1, and an m-bit message M(x) rep-
strate. The cylindrical conductor acts as a
resented as a polynomial of order m − 1, ground plane, the angular strip guides the
c
calculate R(x) = (x M(x))/C(x), then
electromagnetic wave along the longitudinal
construct the transmitted message T(x) = direction.
c
(x M(x)) ⊕ R(x) which is exactly divisible
by C(x). Supposing E(x) represents any er-
rors introduced during transmission, the re- cylindrical stripline the angular strip in
ceiver calculates (T (x) + E(x))/C(x).If the homogeneous media between the two
this is not zero, E(x) is non-zero and the re- cylindrical conductors. The inner and outer
ceived message is erroneous. If this is zero, conductors act as ground planes, the angular
either no errors were introduced or E(x) is strip guides the electromagnetic wave along
such that the CRC is not strong enough to de- the longitudinal direction.
tect the error. A suitable choice of C(x) will
make this unlikely. cylindrical wave an electromagnetic
wave in which each wavefront (surface of
cycloconverter a frequency changing constant phase) forms a cylinder of infinite
converter that synthesizes lower frequency lengthandpropagates intowardoraway from
sinewavesfromportionsofapolyphasesetof the axis of the cylinder. A uniform cylin-
higher frequency sine waves. For example, drical wave has the same amplitude over an
a three-phase, 400 Hz input could be used to entire wavefront; a nonuniform cylindrical
create a 60 Hz supply of any desired phase wave has varying amplitude.
order.
cylndrical-rotor machine a synchronous
machine with a cylindrical rotor containing
cyclotron frequency a frequency of elec-
a distributed field winding and an essentially
tron oscillation in a cyclotron. A frequency
uniform air-gap. This design is limited to two
of circular motion of an electron under mag-
and four pole machines (3600 and 1800 rpm
netic fields applied perpendicularly to the
at 60 Hz) and is usually used in large gener-
plane of the circular motion.
ators. See also salient-pole rotor machine.
cylinder a stack of tracks where these
tracks are at a constant radial position (the
same track number) on a disk or disk pack.

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2000 by CRC Press LLC