Page 72 - Electrical Engineering Dictionary

Babinet principle principle in optics that
states that the diffraction patterns produced
B by complementary screens are the same ex-
cept for the central spot. It can be rigorously
proved both for acoustic and electromagnetic
waves. The Babinet’s principle for scalar
fields is the following: let p be the resul-
B coefficient See loss coefficient. tant field in z> 0 due to the incident field p i
from z< 0 and let p t be the total field when
B-ISDN See broadband integrated the same incident wave falls on the comple-
services digital network. mentary screen. Then, in z> 0,

B-mode display returned ultrasound p + p t = p i
echoes displayed as brightness or gray-scale
levels corresponding to the amplitude versus
back in a motor, the end that supports the
depth into the body.
major coupling or driving pulley.
B-site in a ferroelectric material with the
back EMF See counter-EMF.
chemical formula ABO 3 , the crystalline lo-
cation of the B atom.
back end that portion of the nuclear fuel
cycle which commences with the removal of
B-spline the shortest cubic spline consist-
spent fuel from the reactor.
ing of different three-degree polynomial on
four intervals; it can be obtained by convolv-
back porch a 4.7 microsecond region in
ing four box functions.
the horizontal blanking interval of the NTSC
composite video signal that contains a burst
Babbage, Charles (1792–1871) Born:
of eight to ten cycles of the 3.579545 MHz
Totnes, England
(3.58 MHz) color subcarrier. The back porch
Babbage is best known for his ideas on
occupies 7% of the total horizontal line time;
mechanical computation. Babbage is said to
starting at the end of the horizontal line sync
have been disgusted with the very inaccurate signal and ending with the start of the video.
logarithm tables of his day, as well as ap-
palled by the amount of time and people it backbone wiring that runs within and be-
took to compute them. Babbage attempted tween floors of a building and connects local-
to solve the problem by building mechan- area network segments together.
ical computing engines. The government-
funded Difference Engine was beyond the backfeed in power distribution work,
technology of the craftsman who attempted power which flows from the secondary lines
to build it. Undeterred, Babbage followed into the primary lines through the distribution
this failure with the larger and more complex transformer, e.g.,from an emergency genera-
Analytical Engine (also unfinished). The tor connected to customer load.
ideas behind the Analytical Engine formed
the basis for Howard Aiken’s 1944 Mark backflash an arc which forms along a
I computer. Babbage’s assistant, Ada Au- tower during a lightning strike due to high
gusta, the Countess of Lovelace and the poet tower or footing impedance.
Lord Byron’s daughter, is honored as the first
programmer for her work and because her background (1) refers to the received
meticulous notes preserved the descriptions vector power level of an electromagnetic
of Babbage’s machines. measurement (usually radar cross section)

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2000 by CRC Press LLC