Page 133 - Electrical Engineering Dictionary

tem states (data, program, etc.) is saved at film of one material is deposited on the sur-
specific points (checkpoints), during the pro- face of another by using a radio frequency or
cess execution, to be used for recovery if a other electrical energy source to dissociate a
fault is detected. reactive gas.

checksum checksum is a value used to chemically amplified resist a type of
determine if a block of data has changed. The photoresist, most commonly used for deep-
checksum is formed by adding all of the data UV lithography, which, upon post-exposure
values in the block together, and then find- bake, will multiply the number of chemical
ing the 2’s complement of the sum. The reactions through the use of chemical catal-
checksum value is added to the end of the ysis.
data block. When the data block is examined
(possibly after being received over a serial chemiluminescence light emitted as a
line), the sum of the data values and check- result of a chemical reaction.
sum should be zero.
Chernobyl typically refers to a fire at a
checksum character in data communi- nuclearpowerplantnearKievintheRepublic
cation and storage devices, an extra character of the Ukraine.
is often added at the end of the data so that the
total number of ones in a block, including the chessboard distance the distance be-
checksum character is even. The checksum tween discrete points arising from the
character is used to detect errors within the L ∞ norm. Given two discrete points
data block. x = (x 1 ,...,x n ), y = (y 1 ,...,y n )
on an n-dimensional integer lattice, the
chemical beam epitaxy (CBE) a mate- chessboard distance between x and y is
rial growth technique that uses metal organic max {|x 1 − y 1 |,..., |x n − y n |}. So called
molecules in high vacuum growth cham- because it equals the number of moves made
ber and a controlled chemical reaction on a by a King when going from one position to
heated substrate to grow a variety of II-VI, another in the game of chess. See norm.
III-V, and group IV materials with atomic
layer control. Used to create material struc- chi-squared distribution a probability
tures for a variety of electronic and optical distribution with n degrees of freedom and
devices using quantum wells, heterostruc- probability density function
tures, and superlattices. This growth tech- n −1 x
nique combined aspects of both MBE and x 2 e− u(x)
2
f(x) = n .
n
MOCVD growth. 2 2 0( )
2
chemical laser a laser in which the am-
plification results from one or more chemi- chip (1) a small piece of semiconductor
cal reactions; potentially very powerful with material upon which miniaturized electronic
principal output lines in the mid-infrared. circuits can be built.
(2) an individual MMIC circuit or subsys-
chemical sensor the interface device for tem that is one of several identical chips that
an instrumentation system that determines are produced after dicing up an MMIC wafer.
the concentration of a chemical substance. (3) in direct-sequence spread-spectrum
transmission, the high bandwidth symbols,
chemical vapor deposition (CVD) a pro- or pulses making up the signature sequence.
cess used in the manufacture of integrated They are used to spread the bandwidth of the
circuits or optical fibers whereby a thin solid data in frequency. Usually the time duration

c
2000 by CRC Press LLC