Page 244 - Electrical Engineering Dictionary

echo width in a 2-D scattering problem, eddy current a circulating current in mag-
the width needed to capture the exact amount netic materials that is produced as a result of
of incident power, that when the scattering time-varying flux passing through a metallic
body is replaced by a cylinder, and the cylin- magnetic material.
der radiates the captured power, the amount
of power received at a specified point is the eddy current brake a braking device in
same as that received if the scattering body is which energy is dissipated as heat by gener-
not replaced. Echo width is the 2-D analog of ating eddy currents.
radar cross section in 3-D. The units of echo
width are meters. eddy current drive a magnetic drive cou-
pled by eddy currents induced in an electri-
Eckert, John Presper Eckert is best cally conducting member by a rotating per-
known as one of the designers of ENIAC manent magnet, resulting in a torque that is
(Electronic Numerical Integrator And Calcu- linearly proportional to the slip speed.
lator), an early computer. Like many com-
puter pioneers during World War II, Eckert
eddy current loss the energy wasted in
was looking for more efficient ways of calcu-
sustaining undesirable eddy currents in an
lating trajectory tables for artillery and rang-
electrical conductor.
ing systems for radar. Eckert graduated from
the University of Pennsylvania and remained
EDFA See erbium doped fiber amplifier.
there to work with John Mauchly. Eckert and
Mauchly later formed a company and con-
edge (1) a local intensity discontinuity,
tinued to develop and refine their machine.
often corresponding to the boundary of an
Eckert eventually sold the company to what
object, in an image. See also graph.
would become the Sperry Rand Corporation.
(2) a substantial change, over a small dis-
Here he produced UNIVAC I (Universal Au-
tance, in the values of an image’s pixels —
tomatic Computer), one of the first commer-
typically in the gray level values. Edges can
cially successful computers. The chief im-
be curved or straight and are important be-
provement of this machine over its predeces-
cause they are often the boundaries between
sors was in its use of a stored memory.
objects in an image.
ECL See emitter-coupled logic.
edge condition an electric/magnetic field
ecliptic plane of earth’s orbit around the perpendicular to a dielectric/metallic edge
sun. shows a singular behavior referred to as the
edge condition.
economic dispatch a generation scheme
in which units are utilized such that the great- edge coupled microstrip lines the mi-
est profit is generated for the utility. crostrip lines that have the same ground plane
and are on the same dielectric substrate and
economic interchange an arrangement are parallel to each other. The coupling is
between interconnected electrical power sys- mainly due to the fringing fields at the edges
tems whereby a system can meet its load de- of the lines.
mand by buying power from one or more
of the other systems in the interconnection edge detection the location of edges in
group. an image by computer. See also Canny
operator, gradient edge detector,
ectopic beat a heart beat that originates Marr-Hildreth operator, Sobel operator,
from other than the normal site. straight edge detection.

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2000 by CRC Press LLC