This relationship assumes that
S
y
x
is different
from zero. If
S
y
x
= 0, the relative changes δy
and
δx may be independent. The properties
of relative sensitivity established by differen-
tiation only are tabulated and may be found
in many textbooks and handbooks. See also
absolute sensitivity
,
sensitivity
,
sensitivity
measure
,
semi-relative sensitivity
.
relaxation
(1) a general computational
technique where computations are iterated
until certain parameter measurements con-
verge to a set of values.
(2) the response of a linear time invari-
ant system can be represented as the sum of
the zero-input response (system response to
a zero input function) plus the zero-state re-
sponse (system response to an input func-
tion when the system is in the zero state).
Relaxation is the process of putting a sys-
tem into its zero-state, i.e., all initial condi-
tions are zero and there are no internal energy
stores. A system is considered relaxed if it is
in the zero state. See also
relaxation labeling
,
optimization
.
relaxation labeling
an iterative mathe-
matical procedure in which a system of val-
ues is processed, e.g., by mutual adjustment
of adjacent or associated values, until a stable
state is attained. Especially useful for achiev-
ing consistent optimal estimates of pixel in-
tensities or deduced orientation values for
points on the surface of an object. See also
relaxation
,
optimization
.
relaxation oscillations
the damped out-
put oscillations that occur in some laser os-
cillators when they are perturbed from steady
state.
relaxation time
the time in which the ini-
tial distribution of charge will diminish to 1/e
of its original value.
relay
a device that opens or closes a con-
tact when energized. Relays are most com-
monly used in power systems, where their
function is to detect defective lines or appa-
ratus or other abnormal or dangerous occur-
rences and to initiate appropriate control ac-
tion. When the voltage or current in a relay
exceeds the specified “pickup” value, the re-
lay contact changes its position and causes
an action in the circuit breaker. A decision is
made based on the information from the mea-
suring instruments and relayed to the trip coil
of the breaker, hence the name “relay.” Other
relays are used as switches to turn on or off
equipment.
relay channel
a multiterminal channel in
which the receiver observes the transmitted
signal through two channels: one direct to
the transmitter, the other via an intermediate
transmitter/receiver pair.
reliability
the probability that a compo-
nent or system will function without failure
over a specified time period, under stated
conditions.
reliability criteria
a set of operating con-
ditions that the system operator adheres
to in order to guarantee secure operation.
relocatability
the capability for a program
to be loaded into any part of memory that is
convenient and still execute correctly.
relocation register
register used to facili-
tate the placement in varying locations of data
and instructions. Actual addresses are calcu-
lated by adding program-given addresses to
the contents of one or more relocation regis-
ters.
reluctance
the resistance to magnetic flux
in a magnetic circuit; analogous to resistance
in an electrical circuit.
reluctance motor
a motor constructed on
the principle of varying reluctance of the air
gap as a function of the rotor position with
respect to the stator coil axis. The torque
in these motors arises from the tendency of
the rotor to align itself in the minimum re-
c
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