L
L-band
frequency band of approximately
1–2 GHz.
L-L
See line to line fault.
label
a tag in a programming language
(usually assembly language, also legal in C)
that marks an instruction or statement as a
possible target for a jump or branch.
labeling
(1) the computational problem
of assigning labels consistently to objects or
object components (segments) appearing in
an image.
(2) a technique by which each pixel within
a distinct segment is marked as belonging to
that segment. One way to label an image
involves appending to each pixel of an im-
age the label number or index of its segment.
Another way is to specify the closed contour
of each segment and to use a contour filling
technique to label each pixel within a contour.
ladder diagram
(1) the connection of the
coils and contacts used in a control circuit
shown one line after the other that looks like
a ladder.
(2) a visual language for specifying the
Boolean expressions, which are the core of
the control law of PLC.
laddertron
a microwave vacuum tube os-
cillator with a slow-wave structure coupled
to a single-cavity resonator.
lag
the inability of an imaging tube to re-
spond to instantaneous changes in light. For
measurement purposes, lag has two compo-
nents: rise lag is the response time from dark
to light, whereas decay lag is the response
time from light to dark. Lag is a very short-
term effect, and should not be confused with
image retention, image burn, or sticking.
lag circuit
a simple passive electronic cir-
cuit designed to add a dominant pole to com-
pensate the performance of a given system. A
lag circuit is generally used to make a system
more stable by reducing its high-frequency
gain and/or to improve its position, veloc-
ity, or acceleration error by increasing the
low frequency gain. A nondominant zero is
included in the lag circuit to prevent undue
destabilization of the compensated system by
the additional pole.
lag network
a network where the phase
angle associated with the input–output trans-
fer function is always negative, or lagging