Page 157 - Electrical Engineering Dictionary

Computed torque control.
2. Intersection of the cylindrical extension themachine. Thephasevoltagesandcurrents
with R; of the machine are fed through transformers,
3. B is the projection of the resulting fuzzy then rectified in order to provide DC quanti-
set on Y. ties to the field winding. The components of
If we choose intersection as triangular the exciter are the transformers (voltage and
norm and union as triangular co-norm, then current), rectifiers (including possible gate-
we have the so-called max-min composition circuitry), and power reactors; exclusive of
B = A ◦ R, i.d. all input control elements.
_ h ^ i
µ B (y) = µ A (x) µ R (x, y) . compression (1) in information theory,
x thecompactencoding(withasmallernumber
If we choose algebric product for trian- of bits) I c of a digital image or signal I ob-
gular norm and union as triangular co-norm, tained by removing redundant or nonsignif-
then we have the so-called max-product com- icant information, thus saving storage space
position B = A˜◦R, i.d. or transmission time. Compression is termed
lossless, if the transformation of I into I c is
_
µ B (y) = [µ A (x)µ R (x, y)] . reversible, otherwise it is termed lossy.
x
(2) in signal processing, at given bias lev-
The compositional rule of inference is the els and frequency, the ratio between the small
principal rationale behind approximate rea- signal power gain (p outSS /p incidentSS ) under
soning. small signal conditions and the large signal
Seealsoapproximatereasoning, cylindrical power gain (p outLS /p incidentLS ) at a given input
extension of a fuzzy set, fuzzy relation, power, expressed in decibels. As the input
intersection of fuzzy sets, projection of a amplitude of a signal is increased, the out-
fuzzy set. put signal will eventually cutoff and/or clip
due to saturation, resulting in compression.
compound-connected DC machine a If the large signal is insufficiently large to
direct current machine with two field wind- cause cutout and/or clipping, then the com-
ings in which one field winding is connected pression will be at or near 0 dB.
in series and one field winding is connected
in parallel (shunt) with the armature wind-
G CR = 10 log (p outSS /p incidentSS )
10
ing. The shunt winding may be connected
− 10 log (p outLS /p incidentLS )
ahead of the series winding (long-shunt con- 10
nection), or behind the series winding (short-
shunt connection).
compression coding the lossy (irre-
compound-rectifier exciter a source of versible) or loseless (reversible) process of
field current of a synchronous machine de- reducing the amount of digital information
rived from the phase voltages and currents of required to represent a digital signal.

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2000 by CRC Press LLC