Page 183 - Electrical Engineering Dictionary

duces just enough free neutrons to compen- ture display, above which the presented im-
sate for those lost to the moderator and leak- age ceases to give the appearance of flicker-
age. ing. The critical frequency changes as a func-
tion of luminance, being higher for higher
critical angle the incidence angle, defined luminance.
by Snell’s law, where the incident wave is to-
tally reflected at the interface of two different critical path a signal path from a primary
dielectric media. input pin to a primary output pin with the
longest delay time in a logic block.
critical band broadly used to refer to psy-
choacoustic phenomena of limited frequency
critical point See equilibrium point.
resolution in the cochlea. More specifically,
the concept of critical bands evolved in ex-
critical race a change in two input vari-
periments on the audibility of a tone in noise
ables that results in an unpredictable output
of varying bandwidth, centered around the
value for a bistable device.
frequency of the tone. Increasing the noise
bandwidth beyond a certain critical value has
critical region a set of instructions for
little effect on the audibility of the tone.
a process that access data shared with other
critical clearing angle (1) following a processes. Only one process may execute the
critical region at a time.
balanced three-phase fault at the stator ter-
minals of a synchronous machine, the maxi-
mum value of the angular position of the ro- critical section See critical region.
tor prior to the removal (clearing) of the fault
such that the rotor will obtain synchronous critically sampled sampling that at the
speed without slipping poles following the Nyquist frequency.
removal (clearing) of the fault. The corre-
sponding time for the rotor to achieve this Crosby direct FM transmitter after its
angle is specified as the critical clearing time. inventor, Murray Crosby. Also known as
(2) the largest allowable angular deviation the “serrasoid modulator.” Direct frequency
from synchronism that may be borne by a modulation (FM) of an inductor/capacitor
power system such that the system remains (LC) oscillator is essentially straightforward:
stable: the edge of instability. One of the frequency determining elements
value is varied in accordance with the base-
critical damping the least amount of band information.
damping such that the system does not freely
oscillate. For a characteristic equation of the cross chrominance NTSC video arti-
form: fact that causes luminance information to be
2
2
s + 2ζω n s + ω ,
n present in the decoded chroma signal (lu-
the system is critically damped if ζ = 1.0; minance crosses into chrominance). Cross
the roots of the characteristic equation are chrominance is a result of mixing high
repeated and real. frequency luminance information with the
chrominance information in the composite
critical dimension (CD) the size (width) video signal. An example of cross lumi-
of a feature printed in resist, measured at a nance is the rainbow pattern observed when
specific height above the substrate. tweed or a herringbone pattern appears in a
TV scene.
critical frequency the rate of picture pre-
sentation, as in a video system or motion pic- cross color See cross chrominance.

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2000 by CRC Press LLC