Page 61 - Electrical Engineering Dictionary

representing the quiescent state of a biologi- ten used to reduce aberrations in optical sys-
cal neuron. tems.

artificial skin artificial skin is a de- assembler (1) a computer program that
vice which, when pressed against the surface translates an assembly-code text file to an ob-
by an object, causes local deformations that ject file suitable for linking.
are measured as continuous resistance varia- (2) a program for converting assembly
tions. The latter are transformed into electri- language into machine code.
cal signals whose amplitude is proportional
to the force being applied to any given point assembly language a programming lan-
on the surface of the material of the device. guage that represents machine code in a
symbolic, easier-to-read form. See also
ASAP/RABET acronym for a computer assembler.
code for optical systems by BRO, Inc., for
standard optical analysis and stray-light anal- assert (1) raising the voltage on a wire to
ysis such as light-scattering. the “high” state, usually as a signal to some
other unit.
ASCII See American standard code for (2) to make an assertion.
information interchange.
assertion (1) a Boolean expression for
ASCR Seeasymmetricalsiliconcontrolled stating the right behavior of the program or,
rectifier. if hardware implemented, of a circuit.
(2) a logical expression specifying a pro-
ASIC See application-specific integrated gram state that must exist or a set of condi-
circuit. tions that program variables must satisfy at a
particular point during program execution.
ASK See amplitude-shift keying.
associate mode an operating mode of
askarel a trade name for an insulating oil. content addressable memories, in which a
stored data item is retrieved that contains a
ASM See algorithmic state machine. field that matches a given key.

aspect ratio (1) the size invariant ratio of associated reference directions a
length to width for a rectangular box enclos- method assigning the current and voltage di-
ing a shape, the orientation of the box being rections to an electrical element so that a pos-
chosen to maximize the ratio. This measure itive current-voltage product always means
is used to characterize object shapes as a pre- that the element is absorbing power from the
liminary to, or as a quick procedure for, ob- networkandanegativeproductalwaysmeans
ject recognition. that the element is delivering power to the
(2) the ratio of width to height for an network. This method of assigning direc-
image or display. tions is used in most circuit simulation pro-
(3) in television or motion pictures, the grams.
algebraic ratio of picture width to height. At
present, the television format in the United associative memory a memory in which
States consists of a width to height ratio of 4 each storage location is selected by its con-
to 3. tents and then an associated data location can
be accessed. Requires a comparative with
aspheric description of optical elements each storage location and hence is more com-
whose curved surfaces are not spherical, of- plex than random access memory. Used in

c
2000 by CRC Press LLC