Page 234 - Electrical Engineering Dictionary
P. 234
double heterostructure dye laser laser in double-sided assembly a packaging and
which the amplification takes place in a dye; interconnecting structure with components
a broadly tunable laser. mounted on both the primary and secondary
sides.
double lambda system a quantum me-
chanical system composed of two interact- double-sided disk a disk in which both
ing lambda systems that share common lower sides of a platter are covered with magnetic
states. A double lambda system is also a dou- material and used for storing information.
ble vee system. Double lambda systems can
be used to construct resonant closed loop in- doublet a system of two quadrupole mag-
teractions in which some linear combination nets in close proximity and with opposite
of the phases of the four fields is constant in polarity used to simultaneously constrain
time. the beam size in two dimensions at some
point downstream. Doublet (Quadrupole)
is a beam optical system consisting of two
double line to ground fault See double
quadrupoles of opposite sign, which provides
phase ground fault.
net particle focusing in all planes.
double phase ground fault a fault with
doubly-fed induction motor an induc-
two transmission lines being connected to the
tion motor with a wound-rotor. The rotor
ground.
and stator windings are connected to sepa-
rate sources of electric energy. The machine
doublerevolving-fieldtheory Seecounter-
can be used as a generator to provide fre-
rotating field theory.
quency conversion or precise speed control
in the motor-mode.
double sideband modulation (DSB) a
modulation scheme resulting in a spectrum down-sampling See decimation.
consisting of the carrier frequency, one signal
that is the sum of the carrier and the modu- downconductor the cable which connects
lating signal, and one signal that is the differ- anairterminalorlightningrodtoground. See
ence between the carrier and the modulating air terminal.
signal.
download to bring data from a remote
double tuned a circuit, amplifier, or other source to local storage.
device having a response that is the same as
two single-tuned circuits. downstream in power distribution work,
the direction in which power flows, i.e., to-
wards the load.
double word data block that contains
twice the number of bits as the machine word
DPA See destructive physical analysis.
size in a microprocessor.
DPCM See differential pulse code
double-cage rotor See dual-cage rotor.
modulation.
double-frequencyrecording Seemagnetic DPCM encoding See differential pulse
recording code. code modulation.
double-line contingency a malfunction DPI See dots per inch.
of a power system which involves the simul-
taneous failure of two transmission lines. DPLL See dual phase-locked loop.
c
2000 by CRC Press LLC