Page 140 - Electrical Engineering Dictionary

into the sides of a wooden utility pole, they identifiesthepagetobereplaced. Thepointer
provide purchase for the worker to scale the advances to the next page entry for the next
pole. occasion that the algorithm is required. The
word“clock”comesfromviewingthepointer
clipping nonlinear distortion that occurs as an arm of a clock. Also known as a first-
when the input to an amplifier exceeds the in-not-used-first-out replacement algorithm.
amplifier’s linear range. The amplifier out-
put saturates at its limit, giving a “clipped” clockskew thephenomenonwherediffer-
appearance to the output waveform. ent parts of the circuit receive the same state
of clock signal at different times because it
clock (1) the oscillator circuit that gener- travels in wires with different lengths. This
ates a periodic synchronization signal. skew of the signals causes a processing ele-
(2) a circuit that produces a series of elec- ment to generate an erroneous output. Distri-
trical pulses at regular intervals that can be bution of the clock by means of optical fibers,
used for timing or synchronization purposes. waveguides, a lens, or a hologram, eliminates
clock skew.
clock cycle one complete event of a syn-
chronous system’s timer, including both the clock speed the rate at which the tim-
high and low periods. ing circuit in a synchronous system generates
timing events.
clock doubling a technique in which the
processor operates internally at double the closed convex set a set of vectors C such
external clock frequency. that of x, y ∈ C then λx + (1 − λ)y ∈ C for
all 0 ≤ λ ≤ 1.
clock duty cycle the percentage of time
that the electronic signal remains in the true closed kinematic chain in vision engi-
or 1 state. neering, a sequence of links which forms a
loop.
clock pulse a digital signal that, via its
rising edge or falling edge, triggers a digi- closed-loopcontrol controlactionachieved
tal circuit. Flip-flops and counters typically by a closed feedback loop, i.e., by measuring
require clock pulses to change state. the degree to which actual system response
conforms to desired system response and ap-
clock recovery in synchronous systems, plying the difference to the system input to
the act of extracting the system clock signal drive the system into conformance.
from the received sequence of information
symbols. See also symbol synchronization. closed-loop DC motor acceleration the
use of sensors to provide feedback to the mo-
clock replacement algorithm a page re- tor control circuit indicating the motor is ac-
placement algorithm described as follows: A tually accelerating before the starting resis-
circular list of page entries corresponding to tors are removed from the armature circuit.
the pages in the memory is formed. Each en- Two popular methods to sense motor accel-
try has a use bit which is set to a 1 when the eration are CEMF coils, and current sensing
corresponding page has been referenced. A coils.
pointer identifies a page entry. If the use bit
of the page entry is set to a 1, the use bit is re- closed-loop gain the gain of an opera-
set to a 0 and the pointer advances to the next tional amplifier circuit with negative feed-
entry. The process is repeated until an entry back applied (with the negative feedback
is found with its use bit already reset, which loop “closed”).

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2000 by CRC Press LLC