Page 69 - Electrical Engineering Dictionary

automatic repeat request (ARQ) an er- (2) a machine that follows sequence of in-
ror control scheme for channels with feed- structions.
back. The transmitted data is encoded for (3) any automated device (robots, me-
error detection and a detected error results in chanical and electromechanical chess au-
a retransmission request. tomata). Automata (plural of automa-
ton) theory studies various types of au-
automatic tracking on an optical disk, tomata, their properties and limitations. See
the process in which the position of the disk also cellular automaton, finite state machine
head relative to the disk surface is constantly (FSM).
monitored and fed back to the disk control
system in order to keep the read/write beam autonomic thatpartofthenervoussystem
constantly on track. which controls the internal organs.

automatic transfer switch a self-acting autonomous operation operation of a se-
switch which transfers one or more load con- quential circuit in which no external signals,
ductor connections from one power source to other than clock signals, are applied. The
another. necessary logic inputs are derived internally
using feedback circuits.
automatic voltage regulator (AVR) an
automatic feedback control system that is re- autonomous system a dynamic system
sponsible for maintaining a scheduled volt- described by a first-order vector differential
age either at the terminals of a synchronous equation that is unforced and stationary. In
generator or at the high-side bus of the gen- other words, such a system is governed by an
erator step-up transformer. The control is equation of the form
brought about by changing the level of ex-
citation. ˙ x(t) = f(x(t))
See also unforced system and stationary .
automation refers to the bringing to-
gether of machine tools, materials handling
process, and controls with little worker inter-
autoregressive (AR) a pth order autore-
vention, including
gressive process is a discrete random pro-
1. a continuous flow production process
cess that is generated by passing white noise
that integrates various mechanisms to pro-
through an all-pole digital filter having p
duce an item with relatively few or no worker
poles. Alternatively, x[n] is a pth order AR
operations, usually through electronic con-
process if
trol;
2. self-regulating machines (feedback)
n−1
that can perform highly precise operations in X
x[n]= α[i]x[i]+ q[n].
sequence; and
i=n−p
3. electronic computing machines.
In common use, however, the term is of- Autoregressive processes are often used to
ten used in reference to any type of advanced model signals since they exhibit several use-
mechanization or as a synonym for techno- ful properties. See also moving average.
logical progress; more specifically, it is usu-
ally associated with cybernetics. autotransformer a power transformer
that has a single continuous winding per
automaton (1) a fundamental concept phase, part of this winding being common
in mathematics, computer engineering, and to both the primary and the secondary sides.
robotics. As a result, these voltages are not isolated

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2000 by CRC Press LLC