Page 112 - Electrical Engineering Dictionary

bus tenure the time for which a device wall of a transformer tank so as to insulate
has control of the bus, so locking out other the conductor from the wall.
requesters. In most buses, the bus priority ap-
plies only when a device completes its tenure; bushing transformer a potential trans-
even a low priority device should keep its former which is installed in a transformer
tenure as short as possible to avoid interfer- bushing so as to take advantage of the in-
ence with higher priority devices. See also sulating qualities of that bushing.
bus priority.
busway a specialized raceway which
bus transaction the complete sequence holds un-insulated bus bars in a building.
of actions in gaining control of a bus, per-
forming some action, and finally releasing busy tone multiple access (BTMA) syn-
the bus. See also bus cycle. onym for idle tone multiple access.

bus watching See bus snooping.
busy waiting a processor state in which
it is reading a lock and finding it busy, so it
bus width the number of data lines in a
repeats the read until the lock is available,
given bus interconnect.
without attempting to divert to another task.
The name derives from the fact that the pro-
bus-connected reactor See shunt reactor.
gram is kept busy with this waiting and is not
accomplishing anything else while it waits.
bus yard an area of a generating station or The entire “busy loop” may be only 2 or 3
substation in which bus bars cf and switches instructions.
are located. “Busy waiting” is generally deplored be-
cause of the waste of processing facilities.
Bush, Vannevar (1890–1974) Born: Ev-
Butler matrix a feed system (also called
erett, Massachusetts, U.S.A.
beam-forming system), that can excite an an-
Bushisbestknowasthedeveloperofearly
tenna array so that it produces several beams,
electromechanical analog computers. His
all offset from each other by a finite angle.
“differential analyzer,” as it was called, arose
The system makes use of a number of input
from his position as a professor of power
ports connected through a combination of hy-
engineering at the Massachusetts Institute
brid junctions and fixed phase shifters.
of Technology. Transmission problems in-
volved the solution of first- and second-order
Butterworth alignment a common filter
differential equations. These equations re-
alignment characterized by a maximally flat,
quired long and laborious calculations. His
monotonic frequency response.
interest in mechanical computation arose
from this problem. Bush’s machines were
Butterworth filter an IIR (infinite im-
used by the military during World War II to
pulse response) lowpass filter with a squared
calculate trajectory tables for artillery. Van-
magnitude of the form:
nevarBushwasalsoresponsibleforinventing
the antecedent of our modern electric meter. 2 1
|H(ω)| =
He was also scientific advisor to President jω 2N
1 + ( )
Roosevelt on the Manhattan Project. jω c
bushing a rigid, hollow cylindrical insu- buzz stick a tester for insulators, espe-
lator which surrounds a conductor and which cially strain insulators in a string. It consists
extends through a metal plate such as a the of a pair of probes connected to each side
c
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