Page 126 - Electrical Engineering Dictionary

centrosymmetric medium a material The opening angle of this cone depends on
that possesses a center of inversion symme- the velocity of the particle and on the veloc-
try. Of importance because, for example, ity of light in the medium. The phenomenon
second-order nonlinear optical processes are involved is that of an electromagnetic shock
forbidden in such a material. wave and is the optical analogue of sonic
boom. Cerenkov radiation provides an im-
cepstrum inverseFouriertransformofthe portant tool for particle detection.
logarithm of the Fourier power spectrum of a
signal. The complex cepstrum is the inverse certainty equivalence principle a design
Fourier transform of the complex logarithm method in which the uncertainties of process
of the Fourier transform of the signal. parameters are not considered. Found in self-
tuning regulators where the controller param-
ceramic ferrite a relatively inexpensive eters or the process parameters are estimated
permanent magnet material with decent co- in real-time and are then used to design the
ercivity and low energy product that is com- controller as if they were equal to the true pa-
posed of strontium or barium oxide and iron rameters. Although many estimation meth-
oxide. Also called hard ferrite. ods could provide estimates of parameter un-
certainties, these are typically not used in the
cerebellar model articulation (CMAC) control design.
network a feedforward network devel-
oped originally as a model of the mam- CFD See crossed field devices.
malian cerebellum. Several variants now
exist, but basic operation involves the first CFIE See combined field integral
layer of the network mapping the input into a equation.
higher-dimensional vector and a second layer
forming the network output by means of a CGA See color graphics adapter.
weighted sum of the first layer outputs. The
weights can be trained using the LMS rule. chain code a method for coding thin con-
Developed mainly for application in robotics, tours or lines, for example, in a bilevel pic-
it has also been used in pattern recognition ture, which encodes the direction of move-
and signal processing. Often called a CMAC ment from one point to the next. For 8-
network. connected contours, a three-bit code may be
used at each point to indicate which of its
Cerenkov counter a detector for charged eight neighbors is the succeeding point.
particles. It consists essentially of a trans-
parent medium such as a gas, which emits chain matrix See ABCD matrix.
Cerenkov radiation when a charged particle
passes through at a velocity greater than the chainparameters SeeABCDparameters.
velocity of light in the medium. The mass of
a particle in a beam of known momentum can
be determined with such a counter by mea- chain reaction a process in which high-
suring the characteristic angle at which the energy neutrons emitted from fissile radioac-
Cerenkov radiation is emitted. tive material are directed into more fissile
material such that more neutrons are emit-
Cerenkov radiation light emitted when ted. The process creates heat which is used
a charged particle traverses a medium with a to power thermal power plants.
velocity greater than the velocity of light in
the medium. The Cerenkov light is emitted chaining when the output stream of one
in a cone centered on the particle trajectory. arithmeticpipelineisfeddirectlyintoanother

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2000 by CRC Press LLC