Page 231 - Electrical Engineering Dictionary

of black and white dots is associated with strongest signal among the copies received.
each gray-level, and error-diffusion dither- The weaker signals are simply ignored.
ing, where each gray-level pixel in turn is
assigned an available color, and the error is divide by zero error occurring when a
spread to its unprocessed neighbors (as in the division per zero is operated. This case is
Floyd-Steinberg) method. See halftone. mathematically undefined. In many cases,
this problem is detected directly at level of
divergence the angle that the trajectory of microprocessor that activates an exception
each particle makes with the beam axis. Ac- and leaving true a status flag. The excep-
celerator systems always try to reduce beam tion can be managed for recovering the error
divergence. and avoiding the interruption of the program
execution. Also known as divide per zero.
divergence theorem let us consider a vol-
ume V bounded by a surface S and an outer divide per zero See divide by zero.
normal n. Let also F be a vector function
divider functional unit consisting of
which, together with its partial derivatives,
circuits that implement either integer or
is continuous at all points of V and S. The
floating-point division.
divergence theorem states that
DLL See delay-locked loop.
Z Z
divFdx = F · ndS .
V S
DLT directory look-aside table. See also
translation lookaside buffer.
The above equation may also be used to de-
fine the divergence.
DMA See direct memory access.
diversity combining a communication
DMS Seedistributionmanagementsystem.
technique that combines the signals re-
ceived through different, possibly indepen-
dent channels. The most common methods
DOA direction of arrival. See also angle
of combining are maximum-ratio combining,
of arrival.
equal gain combining, selection combining,
and switched combining. DOF See depth of focus.

diversity frequency a method for in- domain module or area of execution that
creasing the reliability of digital communi- is to be kept isolated from other domains; a
cations in which multiple copies of the sig- domain may have special properties that de-
nal, or other types of redundant informa- fine the nature of the isolation and the limits
tion, are transmitted. Frequency diversity on communication to and from the domain.
implies that the received signal occupies a In the context of secure system design, a do-
much wider bandwidth than the minimum main may be an execution of a process that
bandwidth needed to carry the information. has specific security attributes.

diversitypath aformofdiversityinwhich dominant mode the mode of a waveguide
multiple copies of the signal are created via having the lowest cutoff frequency or of a
different paths from the transmitter to re- cavity having the lowest resonant frequency.
ceiver.
don’t care a function that can be taken
diversity selection a form of diversity either as a minterm or a maxterm at the con-
reception in which the receiver selects the venience of the user.

c
2000 by CRC Press LLC