Page 189 - Electrical Engineering Dictionary

tude of the rate of change of the unit tangent CVD See chemical vapor deposition.
vector with respect to arc length. The curva-
ture of a surface is given in terms of a metric CVQ See classified vector quantization.
tensor which embodies two principal (pla-
nar) curvatures, κ 1 and κ 2 . The curvature of CW See continuous wave.
a surface is sometimes characterized by the
so-called Gaussian curvature κ = κ 1 κ 2 . cybernetics (1) the field of control and
communication theory in general, without
curvature function a function that gives specific restriction to any area of application
curvature values at different locations of a or investigation.
curve or surface. (2) the behavior and design of mecha-
nisms, organisms, and/or organizations that
cut-off frequency the minimum fre- receive and generate information and re-
quencyatwhichawaveguidemodewillprop- spond to it in order to obtain a desired result.
agate energy with little or no attenuation.
cycle See clock cycle.
cut-off rate a measure of reliability of a
cycle stealing an arrangement in which
channel. At information rates below the cut-
a DMA controller or I/O channel, in order
off rate, the probability of error averaged over
to use the I/O bus, causes the CPU to tem-
the ensemble of randomly selected codes can
porarily suspend its use of the bus. The CPU
beforcedtozeroexponentiallywiththe block
is said to hesitate. See also direct memory
length (for block codes), or constraint length
access.
(trellis codes). The cut-off rate is less than or
equal to the channel capacity. Also known
cycle time time required to complete one
as the computational cut-off rate, since for
clock cycle (usually measured in nanosec-
trellis codes, it is at this rate that the ex-
onds).
pected number of computations required to
perform sequential decoding becomes un-
cycles per instruction (CPI) a perfor-
bounded.
mance measurement used to judge the effi-
ciency of a particular design.
cut-off wavelength the wavelength above
which a fiber exhibits single mode operation
cyclic access in devices such as magnetic
(and below which exhibits multimode oper-
and optical disks (and older bubble memo-
ation).
ries) that store data on rotating media, the
property that any individual piece of data can
cutoff frequency See cut-off frequency.
be accessed once during each cycle of the me-
dia.
cutoff rate See cut-off rate.
cyclic code a linear block code where ev-
cut-out a pole-mounted device which erycyclic shift ofacodeword is anothercode-
contains a high-voltage fuse integral with word in the same code. This property is an
a disconnect switch. It is used to protect outcome of the significant algebraic structure
and disconnect primary circuits in distribu- that underlies these codes.
tion work.
cyclic redundancy check (CRC) (1)
cutset a minimal subnetwork, the removal is used to detect transmission errors over
of which cuts the original network into two communication channels in digital systems.
connected pieces. When using the CRC technique, the modulo-

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