Page 98 - Electrical Engineering Dictionary

Boost converter.
varying the duty ratio d. Its main applica- bound mode a type of mode of limited
tion is in regulated DC power supplies and spatial extension. Open waveguides can sup-
the regenerative braking of DC motors. Also port, apart for a continuous spectrum, also
called a step-up converter. a few mode, which do not extend up to in-
finity since they decay exponentially outside
boot See bootstrap. of a certain region. In an optical waveguide
this is a mode whose field decays monoton-
boot record structure at the beginning of ically in the direction transverse to propaga-
a hard disk that specifies information needed tion and which does not lose power to radi-
for the start up and initialization of a com- ation. Bound modes can also be interpreted
puter and its operating system. This record in terms of guided rays and total internal re-
is kept and displayed by the booting program. flection. Note: Except in a monomode fiber,
the power in bound modes is predominantly
bootstrap (1) a technique using positive contained in the core of the fiber. See also
feedback to change the effective impedance continuous spectrum.
at a node, for example, to reduce capacitance.
(2) to initialize a computer system into a boundary a curve that separates two sets
known beginning state by loading the oper- of points.
ating system from a disc or other storage to
computer’sworkingmemory. Thisisdoneby boundary bus one of a set of buses which
a firmware boot program. Also called boot define the boundary between the portion of a
for short. power system to be analyzed and the rest of
the system. Boundary buses are connected
boson an integral spin particle to which to both the internal and external systems.
Bose-Einstien statistics apply. Such particles
do not follow the Pauli exclusion principle. boundary condition (1) the conditions
Photons, pions, alpha particles, and nuclei of satisfied by a function at the boundary of its
even mass numbers are examples of bosons. interval of definition. They are generally dis-
tinguished in hard or soft also called Neu-
bottle slang for glass insulator. mann (the normal derivative of the function
is equal to zero) or Dirichlet (the function
bottom antireflective coating an antire- itself is equal to zero).
flective coating placed just below the pho- (2) the conditions satisfied from the elec-
toresist to reduce reflections from the sub- tromagnetic field at the boundary between
strate. two different media.
(3) rules that govern the behavior of elec-
bottom-up development an application tromagnetic fields as they move from one
development methodology that begins creat- medium into another medium.
ing basic building blocks and uses them to
build more complex blocks for higher levels boundary layer a method of smooth-
of the system. ing out a discontinuous controller or a sliding

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