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Electrical Engineering Dictionary - part 98

kernel

(1) the term for the portion of the

operating system that operates in privileged
mode.

(2) the set of basis functions for a trans-

formation.

(3) the set of convolution weights for fil-

tering.

Kerr coefficients

describes the quadratic

electro-optic effect, particularly for gases and
liquids.

Kerr effect

the quadratic electro-optic ef-

fect, particularly in the case for gases and
liquids.

key

(1) in a table, the value used to select

the desired entry (or entries).

(2) in an access control system, a value

held by a process to permit it to make access
to certain objects within the system.

key point detection

a technique usually

employed in specialized linear or morpho-
logical filters designed for measuring gray-
level changes in several directions. A key
point is an isolated image point correspond-
ing to a peculiar physical or geometrical phe-
nomenon in the scene from which the image
arises; it can be for example a corner, a line
termination, a junction, a bright or dark spot,
etc. Key points are distinguished from edges
by two properties: they are sparse and display
strong gray-level variations in two or more di-
rections (while edge points are grouped into
lines, and have gray-level variations essen-
tially in the direction normal to that line). See

edge

. See also

salient feature

key punch

a device with a keyboard used

for storing data in paper cards or paper tapes
by punching holes.

The pattern of holes

punched across these cards or tapes represent
the data keyed in. Now obsolete.

keyboard

an input device with a set of but-

tons (or keys) through which characters are
input to a computer. In addition to the keys
for inputing characters, a keyboard may also

have function keys and special keys, such as
power-on or print-screen.

keyboard controller

the device controller

that processes keyboard input. Because of its
importance, I/O from the keyboard controller
is often handled differently from other I/O
processes, with its own direct connection to
the CPU.

keystone distortion

a distortion that

presents an image in the shape of a trape-
zoidal. For projection television displays,
off-axis projections of the red and blue tubes
can cause keystone distortion.

For direct

view television displays, unequal deflection
sensitivities for the two sections of the deflec-
tion yoke can result in keystone distortion. A
horizontal trapezoid is the result of the verti-
cal yoke deflection sensitivities. Similarly, a
vertical trapezoid is the result of the horizon-
tal yoke deflection sensitivities.

KGD

See

known good die

Kharitonov theorem

the most popular

necessary and sufficient condition of robust
stability for characteristic interval polynomi-
als. It states that robust stability of uncertain
linear time-invariant system with character-
istic interval polynomial

p(s, a) is stable if

and only if the following four polynomials
have all roots endowed with negative parts:

(s) = a

−

s+a

−

+...

(s) = a

s+a

−

+...

(s) = a

−

s+a

−

+...

(s) = a

−

s+a

−

+...

where

−

, a

are bounds for coefficients of

the characteristic interval polynomial. The
polynomials are called Kharitonov polyno-
mials, and the required property could be
checked by four Routh–Hurwitz tests. Some
generalizations of this result for dependent

2000 by CRC Press LLC

coefficient perturbations and more general
zero location regions are known.

Kilby, Jack St. Clair

(1923– )

Born:

Jefferson City, Missouri, U.S.A.

Kilby is best known as the person who

first suggested and then implemented the
concept of integrating transistors, with ca-
pacitors and resistors, on a single silicon
wafer.

This concept, simple-sounding to-

day, formed the basis for the first early in-
tegrated circuits. Kilby’s employer, Texas
Instruments, launched a patent suit against
Fairchild Industries to establish their and
Kilby’s claim to the technology. The court
ruled in favor of Robert Noyce and Fairchild.
Despite this, Kilby is universally recognized
for his pioneering work, especially in the
practical implementation of IC technology.

kilovar

See

VAR

kilovolt-ampere (KVA)

a measure of ap-

parent power, often in the rating of a piece
of equipment or the measure of an electrical
load, which is obtained by multiplying the
device voltage in kilovolts by the current in
amperes.

kilowatt-hour (KWH)

a measure of elec-

trical energy: 1000 watts delivered for one
hour.

kinematic calibration

a procedure to

finding accurate estimates of Denavit–Harten

berg parametersfromaseriesofmeasurements

of the manipulator’s end-effector locations.

See also

Denavit–Hartenberg notation

kinematic singularity

a point for which

the geometric Jacobian is not invertible. In
other words, those configurations at which
Jacobian is rank-deficient are termed kine-
matic singularities. As a consequence, in sin-
gular configurations infinite solutions to the
inverse kinematics problem may exist. From
practical point of view small velocities in the
operation space will cause large velocities in
the joint space.

kinematically simple manipulator

a ma-

nipulator where some or all link offset angles
equal 0,

−90

◦

, or 90

◦

and link distances and

offsets equal zero. Kinematically simple ma-
nipulators are found in most of the industrial
robots. For these robots, forward kinematics
problem can be solved in a closed form solu-
tion and dynamics equations are the simplest.
See also

Denavit–Hartenberg notation

kinetic energy

energy of motion.

kinetic energy conservation principle
any change of kinetic energy of an electron
is transformed into a change in electric po-
tential energy with which the electron is in-
teracting, and vice versa.

kineto-static duality

the static relation-

ship combined with the differential kinemat-
ics equation defines a kineto-statics duality.
For the description of differential kinematics.
See

differential kinematics

. The static rela-

tionship describes the end point force and
equivalent joint generalized force balance as-
suming that we neglect gravity and friction
at the joints. This relationship is described
by the transpose of the manipulator Jacobian
and has the form

τ = J

F , where F is a

vector of exerted end point forces and

τ is a

vector of joint generalized forces. As a con-
sequence of the last definition, the following
properties can be defined.

1. The range of

is the subspace

R(J

)

of the joint forces and/or torques that

can balance the end-effector forces, in the
given manipulator posture.

2. The null of

is the subspace

N(J

) in

of the end-effector forces and/or torques

that do not require any balancing joint gener-
alized forces, in the given manipulator pos-
ture.

Kirchhoff, Gustav Robert

(1824–1887)

Born: Konigsberg, Germany

Kirchhoff is best known for discovering

the laws that govern electric flow in networks,
known now as Kirchhoff’s laws. Kirchhoff is
also famous as the inventor of spectroscopy,

2000 by CRC Press LLC

and his theoretical work led to the quan-
tum theory of matter. Kirchhoff first held a
teaching post in Berlin, followed by appoint-
ments in Breslau and Heidelberg. In the latter
two universities, Kirchhoff had very fruitful
collaborations with Robert Bunsen. Kirch-
hoff’s studies in electricity provided a foun-
dation for Maxwell and Lorenz’s description
of electromagnetic theory.

Kirchoff’s current law (KCL)

a funda-

mental law of electricity that states that the
sum of the currents entering and exiting a cir-
cuit node must be equal to 0.

Kirchoff’s laws

laws that govern the rela-

tionships between voltages/currents in a cir-
cuit/network.

See also

Kirchoff’s voltage

law

Kirchoff’s current law

Kirchoff’s voltage law (KVL)

a funda-

mental law of electricity that states that the
sum of the voltage drops and rises in a closed
loop must equal 0.

Kleinman symmetry

See

symmetries of

nonlinear susceptibility

KLT

See

Karhunen–Loeve transform

klydonograph

a measuring instruments

for high-voltage impulses which makes use
of Lichtenburg figures impressed on photo-
graphic film.

klystrode

an amplifier device for UHF-

TV signals that combines aspects of a tetrode
(grid modulation) with a klystron (velocity
modulation of an electron beam). The result
is a more efficient, less expensive device for
many applications. (Klystrode is a trademark
of EIMAC, a division of Varian Associates.)

knife-edge diffraction

classical diffrac-

tion model defined by the interaction of
a propagating electromagnetic wave with a
perfectly conducting, infinitely thin obstruct-
ing boundary. Knife-edge diffraction is often

used is terrain propagation calculations as an
approximation for hills and ridges.

knob-and-tube wiring

a form of residen-

tial wiring, now obsolete, in which lightly-
insulated wires are supported on porce-
lain insulators (knobs) or porcelain bushings
(tubes) through joists or studs.

knowledge engineering

the process of

developing an expert system.

Knowlton’s technique

a pyramidal type

of hierarchical approach, in which a re-
versible transformation takes adjacent pairs
of k-bit pixel values and maps it into a k-bit
composite value and a k-bit differentiator.

known good die (KGD)

bare silicon chips

(die) tested to some known level.

Kogelnik transformation

See

ABCD

law

K¨ohler illumination

a method of illu-

minating the mask in a projection imaging
system whereby a condenser lens forms an
image of the illumination source at the en-
trance pupil (entrance aperture) of the objec-
tive lens, and the mask is at the exit pupil of
the condenser lens.

Kohonen network

a 2-dimensional array

of neurons with each neuron connected to the
full set of network inputs. Learning is unsu-
pervised: the neuron whose vector of input
weights is closest to an input vector adjusts
its weights so as to move closer to that input
vector; the neuron’s neighbors in the array
adjust their input weights similarly. As a re-
sult, clusters of weights in different parts of
the array tend to respond to different types of
input.

Kolmogorov complexity

the minimum

length description of a binary string that
would enable a universal computer to recon-
struct the string.

2000 by CRC Press LLC

Kraft inequality

a theorem from infor-

mation theory that sets a restriction on instan-
taneous codes (codes where no codeword is
a prefix of any other codeword, i.e., a code
containing 0 and 01 is not an instantaneous
code). The Kraft inequality states that for an
instantaneous code over an alphabet with size
D and codeword lengths l

, l

, . . . , l

the

following must be true:

i=1

−l

<= 1.

Kramer drive

an electric drive system

in which the output of the driven frequency
converter is fed to the slip rings of the wound
rotor. Unlike its predecessor Leblanc system,
the variable transformer is connected to the
wound rotor slip rings instead of to the line.

Kramer’s generalization

a sampling the-

ory based on other than Fourier transforms
and frequency.

Kramers–Kronig relations

relates the

real and imaginary components of the index
of refraction of a medium. See also

Hilbert

transform

Kronecker delta function

The discrete-

time unit impulse function defined as

= 1

for

i = j, δ

= 0 for i 6= j. See also

delta

function

ku-band

frequency band of approxi-

mately 11–12 GHz.

Kubo formula

a fundamental relation-

ship, developed by Ryogo Kubo, between,
e.g., the conductance and the current fluctu-
ations. The Kubo formula is an example of
the fluctuation–dissipation theorem in statis-
tical physics, in which the average value of
the current (conductance) is determined by
an integral over the correlation function of
the current fluctuations.

Kullback–Liebler distance

See

relative

entropy

Kuroda’s identities

four identities are

used to achieve practical microwave filter im-
plementation by using redundant transmis-
sion line sections.

kVA

See

kilovolt-ampere

Kvhler illumination

a method of illu-