Electrical Engineering Dictionary - part 109

(2) for semiconductor manufacturing, a

device used to selectively block photolitho-
graphic exposure of sensitized coating used
for preventing a subsequent etching process
from removing material. A mask is analo-
gous to a negative in conventional photogra-
phy.

(3) a glass or quartz plate containing in-

formation (encoded as a variation in transmit-
tance and/or phase) about the features to be
printed. Also called a photomask or a reticle.

(4) in image processing, a small set of pix-

els, such as a 3

×3 square, that is used to trans-

form an image. Conceptually, the mask is
centered above every input pixel, each pixel
in the mask is multiplied by the correspond-
ing input pixel under it and the output (trans-
formed) pixel is the sum of these products. If
the mask is rotated 180

◦

before the arithmetic

is performed, the result is a 2-D convolution
and the mask represents the impulse response
function of a linear, space-invariant system.
Also called a kernel. See also

convolution

impulse response

kernel

mask aligner

a tool that aligns a pho-

tomask to a resist-coated wafer and then ex-
poses the pattern of the photomask into the
resist.

mask biasing

the process of changing the

size or shape of the mask feature in order for
the printed feature size to more closely match
the nominal or desired feature size.

mask blank

a blank mask substrate

(e.g., quartz) coated with an absorber (e.g.,
chrome), and sometimes with resist, and used
to make a mask.

mask linearity

the relationship of printed

resist feature width to mask feature width for
a given process.

mask programming

programming a

semiconductor read-only-memory (ROM)
by modifying one or more of the masks used
in the semiconductor manufacturing process.

mask set

consists of the dozen or so

(varies with process and company) individual
masks that are required to complete a MMIC
wafer fabrication from start to finish. Exam-
ples of masks or mask levels are “first level
metal” (defines all the primary metal struc-
ture on the circuit), “capacitor top plate” (de-
fines the pattern for the metal used to form the
top plate of MIM capacitors), and “dielectric
etch” (defines areas where dielectric (insula-
tor) material will be removed after coating
the entire wafer with it).

maskable interrupt

interrupt that can be

postponed to permit a higher-priority inter-
rupt by setting mask bits in a control register.
See also

nonmaskable interrupt

masking

a phenomenon in human vision

in which two patterns

and

+ P

cannot

be discriminated even though

is visible

when seen alone.

is said to mask

mass storage

a storage for large amounts

of data.

massively parallel architecture

a com-

puter system architecture characterized by
the presence of large numbers of CPUs that
can execute instructions in parallel.

The

largest examples can process thousands of
instructions in parallel, and provide efficient
pathways to pass data from one CPU to an-
other.

massively parallel processor

a system

that employs a large number, typically 1000
or more, of processors operating in parallel.

master

the system component responsi-

ble for controlling a number of others (called
slaves).

master boot record

a record of the disk

containing the first code and table that are
loaded at the bootstrap of the computer. It is
read even before the partition table sector.

2000 by CRC Press LLC

master control relay (MCR)

used in

programmable logic controllers to secure en-
tire programs, or just certain rungs of a pro-
gram. An MCR will override any timer con-
dition, whether it be time-on or time-off, and
place all contacts in the program to a safe
position whenever conditions warrant.

master copy

in coherence protocols, the

copy of the object that is guaranteed to hold
the “correct” contents for the object. Coher-
ence protocols can be designed around the
tagging of master copies. The master copy
can be read (rather then the copy in slower
memory) to speed program execution, and it
can be written, provided that all other copies
are invalidated. See also

MESI protocol

master-oscillator-power-amplifier
(MOPA)

laser system in which the out-

put from a highly stabilized low-power laser
oscillator is amplified by one or more high-
power laser amplifiers.

master–slave flip-flop

a two-stage flip-

flop in which the first stage buffers an input
signal, and on a specific clock transition the
second stage captures and outputs the state
of the input.

matched filter

a filter matched to a certain

known signal waveform. The matched filter
is the complex conjugate of the known sig-
nal waveform. If the known signal waveform
falls in the matched filter, the output sample
at the optimum sampling instant gives the re-
ceived signal energy.

matched load

load that does not reflect

any energy back into the transmission line.
It could be a load equal to the characteristic
impedance of the transmission line or a struc-
ture with electromagnetic absorbing proper-
ties.

matched uncertainty

See

matching

condition

matching

when referring to circuits, the

process by which a network is placed be-
tween a load and a transmission line in or-
der to transform the load impedance to the
characteristic impedance of said line and thus
eliminate the presence of standing waves on
the line.

matching condition

the condition that re-

quires that the uncertainties affect the plant
dynamics the same way as the control input
does. For example, in the following model of
a dynamical system, the matching condition
is satisfied,

˙x = Ax + B(u + d),

where the vector function d models matched
uncertainties.

matching conditions

conditions imposed

on the structure of the uncertainty, which may
be viewed as the assumption that uncertainty
drives the state equations not stronger than
a control variable. For linear systems, the
matching conditions are given as the assump-
tions imposed on the perturbations of system
matrices

1A, 1B and disturbances Cv(t) in

the following way:

1A = BD; 1B = BG; C = BF

where

D, G, F are unknown but bounded

matrices and

B is an input matrix. It enables

to describe the uncertain linear system by the
following state equation:

˙x = Ax + B(u + e)

where

e is the entire system uncertainty

moved into the input of the system.

matching elements

elements such as

posts, screws, etc., often used in order to
achieve the desired reflection coefficient of
a given microwave component.

matching network

an electric circuit de-

signed to maximize the transfer of electric
power from an electrical source to an elec-
trical load. Maximum power is transferred

2000 by CRC Press LLC

from a source with an output impedance
that is the complex conjugate of the in-
put impedance of the load it is driving. A
matching network is connected between a
source and its load. Its input impedance is
the complex conjugate of the source output
impedance, while its output impedance is the
complex conjugate of the load impedance,
thereby matching the source to the load and
ensuring maximum transfer of power.

matching stub

matching technique that

employs short-circuited (or open-circuited)
sections of transmission lines as reactive el-
ements.

material dispersion

wavelength depen-

dence of the pulse velocity. It is caused by the
refractive index variation with wavelength of
glass.

math coprocessor

a separate chip, addi-

tional to the CPU, that offloads many of the
computation-intensive tasks from the CPU.

mathematical modeling

a mathematical

description of the interrelations between dif-
ferent quantities of a given process. In par-
ticular, a mathematical description of a rela-
tion between the input and output variables of
the process. See also

truth model

and

design

model

mathematical morphology

an alge-

braic theory of non-linear image transfor-
mations based on set-theoretical (or lattice-
theoretical) operations, which is generally
considered as a counterpart to the classical
linear filtering approach of signal process-
ing. This methodology in image processing
arose in 1964 through the works of Math-
eron and Serra at Fontainebleau (France),
was developed in the seventies by Sternberg
at Ann Arbor (Mich.), and became interna-
tionally known in the eighties. It has been
successfully applied in various fields requir-
ing an analysis of the structure of materi-
als from their images, for example biomedi-
cal microscopy, stereology, mineralogy, pet-

rography.

See

closing

dilation

erosion

morphological operator

opening

matrix

n by m matrix is an array of

n×m numbers of height n and width m repre-
senting a linear map from an

m-dimensional

space into an

n-dimensional space. An ex-

ample of a 2

× 2 real matrix is A =

2 3
5 6

See also

circulant matrix

Hermitian matrix

orthogonal matrix

positive definite matrix

matrix addressing

the control of a dis-

play panel consisting of individual light-
producing elements by arranging the con-
trol system to address each element in a
row/column configuration.

matrix element

in quantum mechanics,

the expectation value of a quantum mechan-
ical operator that is associated with a partic-
ular pair of basis states. The term matrix el-
ement derives from the fact that the expecta-
tion values associated with all possible pairs
of states can be written as a matrix.

matrix of configuration of information sys-
tem

in Pawlak’s information system

S =

(U, A) whose universe U has n members x

and the set

A consists of attributes a

, the el-

ements of the universe are linked with each
other. Connections between the elements of
the universe

U may be given, for example,

by a function

ϕ : U × U → {−1, 0, 1}.

The pair

(U, ϕ) is called the configuration

of the information system

S. The matrix of

the information system

S is an n × n matrix

whose elements are

= ϕ x

, x

matrix optics

formalism for the analy-

sis and synthesis of optical systems in which
each system element is represented by a ma-

2000 by CRC Press LLC

trix, the overall system being representable
as a product of the elemental matrices.

matrixing

in a color television trans-

mitter, the process of converting the three
color signals (red, green, blue) into the color-
difference signals that modulate the chromi-
nance subcarrier.

In a color TV receiver,

the process of converting the color-difference
signals into the red, green, and blue signals.

Mauchley, John Graham

(1907–1980)

Born: Cincinnati, Ohio, U.S.A.

Mauchley is best known as one of the de-

signers of ENIAC, an early electronic com-
puter. It was Mauchley, in 1942, who wrote a
proposal to the Army for the design of a cal-
culating machine to calculate trajectory ta-
bles for their new artillery. Mauchley was
a lecturer at the Moore School of Electrical
Engineering at the time.

The school was

awarded the contract and he and J. Pres-
per Eckert were the principal designers of
ENIAC. They later went on to form their own
company. Mauchley was the software engi-
neer behind the development of one of the
first successful commercial computers, UNI-
VAC I.

max operation

an operation on two or

more variables where the resultant value is
formed by taking the largest value, or maxi-
mum, among these variables.

Max–Lloyd scalar quantization

See

Lloyd–Max scalar quantization

Max–Lloyd SQ

See

Lloyd–Max scalar

quantization

max-min composition

a frequently used

method of composition of two fuzzy relations
which, as the name implies, makes use of the
min operation followed by the max operation.

maximal area density (MAD)

for a mag-

netic disk, the maximum number of bits that
can be stored per square inch. Computed by

multiplying the bits per inch in a disk track
times the number of tracks per inch of media.

maximally flat

a circuit response in which

the low-pass prototype attenuation loss (ex-
pressed in decibels) has a smooth response.

maximally flat delay (MHD) filter

a filter

having a time delay that is as flat (constant) as
possible versus frequency while maintaining
a monotonic characteristic.

maximum a posteriori probability

the

probability of a certain outcome of a random
variable given certain observations related to
the random variable, i.e.,

x was transmitted

and

y was received, then P (x|y) is the a pos-

teriori probability. The maximum a poste-
riori probability is found by considering all
valid realizations of

For example, between two strings A and

B it is defined as

MP P

= P r{B|A}

where

P r(B|A) is the probability that A is

changed into

B. Sometimes called maximum

posterior probability (MPP) even though,
strictly speaking, it is a similarity rather than
distance measure.

maximum a posteriori (MAP) estimator
to estimate a random

x by maximizing its

posterior probability; that is,

ˆx

MAP

= arg

max

p(x|y),

where

y represents an observation. x is ex-

plicitly modeled as a random quantity with
known prior statistics. See also

maximum

likelihood estimation

See also

maximum accumulated matching

a de-

fuzzification scheme for a classification prob-
lem in which a pattern is assigned to the class
outputed by the rules that accumulates the
maximum firing degree.

2000 by CRC Press LLC

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