Page 265 - Electrical Engineering Dictionary

essary to estimate them recursively. A basic clidean or digital plane, the Euler number
technique used for parameters estimation is is equal to the number of connected com-
the Least Squares Method. This method is ponents of that object, minus the number of
particularly useful if the model has the prop- holes in it. For 2-D binary digital figures on
erty of being linear in the parameters. a bounded grid, the Euler number can easily
be computed by counting the number of oc-
estimator any function of the sample currences of some local configurations of on
points. Hence, an estimator is a random vari- and off pixels. Also called genus.
able. To be useful, an estimator must have a
good relationship to some unknown quality eureka in a multiprocessor system, a co-
that we are trying to determine by experi- ordination (synchronization) operation gen-
ment. erating a completion signal that is logically
ORed among all processors participating in
etching a reactive process where mate- an asynchronously parallel action. The in-
rial is removed from a semiconductor device terpretation and name come from its use in
or printed circuit board. Usually a photo- systems that delegate various portions of a
sensitive material is exposed through a pho- search space to different processing modules.
tomask, and either a wet chemical process or A processor executes the eureka operation
a dry plasma process is used to selectively when it has found the desired object or value;
remove material to leave a particular pattern thiscanserveasasignalfortheotherstoabort
behind after the etch process is completed. their attempts to find a solution.

Ethernet a standard for interconnecting eutectic alloy composition with minimum
devices on a local area network (LAN). melting temperature at the intersection of two
solubility curves.
Euclidean distance a distance measure
between two real valued vectors (x 1 ,x 2 ,..., eutectic alloy overload device an over-
x n ) and (y 1 ,y 2 ,...,y n ) defined as load device that employs a melting alloy as
the actuating element. See also overload
v
u n
uX heater, overload relay.
D Euclidean = t (x i − y i ) 2
i=1 EUV lithography lithography using light
Euclidean distance is the special case of of a wavelength in the range of about 5 to
Minkowski distance when λ = 2. See also 50 nm, with about 13 nm being the most com-
Minkowski distance. mon. Also called soft X-ray lithography.

Euler number a topological invariant of even function a real-valued function x(t)
an object having an orientable surface. As- in which x(−t) =−x(t) for all values of t.
suming that the surface is endowed with the Compare with odd function.
structure of a graph with vertices, edges, and
faces (where two neighboring faces have in even mode impedance characteristic
common either a vertex or an edge with its impedance of a transmission line when a sin-
two end-vertices, their interiors being dis- gle and certain even mode exists on it.
joint): the Euler number is V − E + F,
where V , E, and F are respectively the num- even order response a circuit gain or
ber of vertices, edges and faces; this number insertion loss versus frequency response in
V − E + F does not depend on the choice which there are an even number of peaks in
of the subdivision into vertices, edges, and the ripple pattern, due to an even number of
faces. For a bounded 2-D object in a Eu- paired elements in the circuit. Even order cir-

c
2000 by CRC Press LLC