US. Patent No. 6,239,614
`
`A ("RC l-Inntlhuok I’llhlih‘hcd in Cooperation with IHL'I: l’rcx'x
`AMD EX1035
`U.S. Patent No. 6,239,614
`
`AMD EX1035
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`MW
`DICTIONARY
`
`CRC PRESS ® IEEE PRESS
`
`0001
`
`

`

`COMPREHENSIVE
`
`DICTIONARY
`
`EEchiNENE
`ENEINEEINNE
`
`EDITOR-IN-CHIEF
`Phillip A. Laplante
`
`CRC PRESS Q IEEE PRESS
`
`A CRC Handbook Published in Cooperation with IEEE Press
`
`0002
`
`0002
`
`

`

`Acquiring Editor: Ran Powers
`Production Manager: Suzanne lassondrc
`Project Editor: Susan Fax
`Cover Design: Jonathan Fennel!
`
`Library of Congress Catelog‘lng-ln-Publication Data
`
`Comprehensive dictionary of electrical engineering 4' Phillip Lsplartte. editor-in-chief.
`p.
`cm.
`Includes bibliographical references (p.
`ISBN 0-8493-3128-5 (alk. paper)
`lSBN 3-540-64335-6
`
`).
`
`I. Electric engineering -—- Dictionaries.
`T130575 I999
`621.3'03—dc21
`
`l. Laplante. Phillip A.
`
`98-44776
`ClP
`
`This book contains information obtained from authentic and highly regarded sources. Reprinted material is quoted
`with permission, and sources are indicated. A wide variety of references are listed. Reasonable efforts have been made
`to publish reliable data and information. but the author and the publisher cannot assume responsibility for the validity
`of all trrateriais or for the consequences of their use.
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`Trademark Notice: Product or cororate names may be trademarks or registered trademarks. and are used only for
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`9 1999 by CRC Press LLC
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`No claim to original US Government works
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`Library of Congress Card Number 98-44176
`PrintedintheUnitedStatesofAmei-ica l 2 3 4 5 6 7 3 9 0
`Printed on acid-free paper
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`0003
`
`0003
`
`

`

`gain vs. frequency response curve has decreased
`—3 dB from the passband reference gain. Note
`that f. and f2 define the response passband by
`marking the points at which the output power
`has decreased to one-half the value of the input
`power. For band widths extending down to DC,
`the upper —3 dB frequency is cited as the 3 dB
`bandwidth.
`
`a method of coupling a
`aperture coupling
`transmission line to an antenna in which fields
`
`leak through an aperture in a metallic ground
`plane separating the line from the antenna.
`
`a figure of merit that de-
`aperture efficiency
`termines how much of the incident energy is cap-
`tured by an aperture. It depends on the physical
`dimensions of the aperture.
`
`APL
`
`See average picture level.
`
`APLC See active power line conditioner.
`
`(1) a deliberate variation in the
`apodization
`transmission of an optical aperture as a function
`of distance from the center or edges, in order to
`control optical transfer functions.
`(2) a deliberate variation in the strength of a
`signal with time.
`
`within an interval of
`apparent concurrency
`time more than one process executes on a com-
`puter. although at the instruction level,
`instruc—
`tions from only one process run at any single
`point in time. See also concurrency.
`
`the
`(1) in an AC system.
`apparent power
`product of voltageI E and current, I. Apparent
`power (or total power) is composed of two mutu-
`ally independent components — an active com-
`ponent (real power), and a reactive component
`(imaginary power). Apparent power is denoted
`by S, and has the unit of voltamperes.
`(2) the scalar product of the voltage and cur-
`rent delivered to the load. It can also be expressed
`
`approximately controllable system
`
`as the vector S = P+j Q. where P 2 real power
`and Q = reactive power.
`
`application-specific integrated circuit (ASIC)
`an integrated circuit designed for one particular
`application.
`
`the technology that
`appropriate technology
`will accomplish a task adequately given the re-
`sources available. Adequacy can be verified
`by determining that increasing the technologi-
`cal content of the solution results in diminishing
`gains or increasing costs.
`
`a process, defined with
`approximate coding
`respect
`to exact coding,
`that deals with ir-
`reversible and information—lossy processing of
`two-level pictures to improve compression ratio
`with significant degradation of picture quality.
`Exact coding schemes depend on the ability to
`predict the color of a pixel or the progression of
`a contour from line to line. Irreversible process-
`ing techniques try to reduce prediction errors by
`maintaining the continuity of the contours from
`line to line. With predictive coding the number
`of pixels can be changed to reduce those having
`nonzero prediction error. With block coding the
`compression efficiency can be improved by in-
`creasing the probability of occurrence of the all
`zero block. The third approximate block coding
`scheme is pattern matching.
`In this scheme the
`identification codes of the repeated patterns are
`transmitted to the receiver. A library of patterns
`is maintained for continuous checking. See also
`exact coding.
`
`an inference proce—
`approximate reasoning
`dure used to derive conclusions from a set of
`
`fuzzy if—then rules and some conditions (facts).
`The most used approximate reasoning methods
`are based on the generalized modus ponens. See
`also fuzzy if—then rule. generalized modus po-
`nens. linguistic variable.
`
`approximately controllable system
`
`an
`
`31
`
`0004
`
`0004
`
`

`

`the service quality temporarily downgrades and,
`in analogue systems. is noticeable as clicking.
`
`two metal spikes, each of which is
`climbers
`strapped to the inside of a line worker’s legs.
`pointing down near the ankle. Plunged into the
`sides of a wooden utility pole. they provide pur-
`chase for the worker to scale the pole.
`
`nonlinear distortion that occurs when
`clipping
`the input to an amplifier exceeds the amplifier‘s
`linear range. The amplifier output saturates at its
`limit. giving a “clipped" appearance to the output
`waveform.
`
`(1) the oscillator circuit that generates
`clock
`a periodic synchronization signal.
`(2) a circuit that produces a series ot‘electrical
`pulses at regular intervals that can be used for
`timing or synchronization purposes.
`
`one complete event of a syn—
`clock cycle
`chronous system’s timer. including both the high
`and low periods.
`
`a technique in which the pro-
`clock doubling
`cessor operates internally at double the external
`clock frequency.
`
`the percentage of time that
`clock duty cycle
`the electronic signal remains in the true or I state.
`
`a digital signal that. via its ris-
`clock pulse
`ing edge or falling edge. triggers a digital circuit.
`Flip-flops and counters typically require clock
`pulses to change state.
`
`in synchronous systems. the
`clock recovery
`act ofextracting the system clock signal from the
`received sequence of information symbols. See
`also symbol synchronization.
`
`clock replacement algorithm a page replace—
`ment algorithm described as follows: A circular
`list of page entries corresponding to the pages in
`
`closed-loop DC motor aeeeleratlon
`
`the memory is formed. Each entry has a use bit
`which is set to a I when the corresponding page
`has been referenced. A pointer identifies a page
`entry. If the use bit of the page entry is set to a
`l. the use bit is reset to a 0 and the pointer ad-
`vances to the next entry. The process is repeated
`until an entry is found with its use bit already re-
`set. which identifies the page to be replaced. The
`pointer advances to the next page entry for the
`next occasion that the algorithm is required. The
`word “clock" comes from viewing the pointer as
`an arm of a clock. Also known as a first-in-not-
`
`used-first-out replacement algorithm.
`
`the phenomenon where different
`clock skew
`parts of the circuit receive the same state of clock
`signal at di fferent times because it travels in wires
`with different lengths. This skew of the signals
`causes a processing element to generate an erro-
`neous output. Distribution of the clock by means
`of optical fibers. waveguides, a lens. or a holo-
`gram. eliminates clock skew.
`
`the rate at which the timing circuit
`clock speed
`in a synchronous system generates timing events.
`
`closed convex set
`
`a set of vectors C such that
`
`ofx.y E C then Rx + (l — My E C for all
`OEAEL
`
`in vision engineering.
`closed kinematic chain
`a sequence of links which forms a loop.
`
`control action achieved
`closed-loop control
`by a closed feedback loop. i.e., by measuring the
`degree to which actual system response conforms
`to desired system response and applying the dif-
`ferencc to the system input to drive the system
`into conformance.
`
`the use
`closed-loop DC motor acceleration
`of sensors to provide feedback to the motor con-
`trol circuit indicating the motor is actually accel-
`erating before the starting resistors are removed
`from the armature circuit. Two popular methods
`
`109
`
`0005
`
`0005
`
`

`

`tory over a given time interval or to be kept at
`a prescribed constant value, i.e.. at a specified
`set-point; introduction of a set of controlled vari-
`ables is necessary to define a two-layer industrial
`controller with the regulation direct control layer
`and the set point optimizing control layer.
`See also controller.
`
`(I) the entity that enforces the de-
`controller
`sired behavior — as specified by the control ob-
`jectives —-- of the controlled process by adjust-
`ing the manipulated inputs. The values of these
`inputs are either predetermined or decided upon
`(computed) using on-line. i.e.. real time, decision
`mechanism of the controller —- based on the cur-
`
`rently available information. See also controlled
`variable.
`
`{2} a device that generates the input to the
`plant or process. The role of the controller is
`to force the controlled variable of the plant or
`process to behave in a desired manner.
`
`(3} aunit thatdirects the operation of a subsys~
`tern within a computer. For instance. a disk con-
`troller interprets data access commands from host
`computer (via a bus), and sends readfwrite. track
`seeking, and other control signals to the drive.
`During this time. the computer can perform other
`tasks. until the controller signals DATA READY
`for transfer via the CPU bus.
`
`a current in which elec-
`convection current
`trons are released for movement outside of a ma—
`terial.
`
`the process by
`convective heat transfer
`which a moving fluid transfers heat to or from
`a wetted surface.
`
`the condition when the electron
`convergence
`beams from a multi-beam CRT meet at a single
`point. For example. the correct registration of
`the three beams in the color picture tube.
`
`convolution
`
`quences of random numbers. the tendency to a
`single number.
`To wit. for a sequence of numbers at... and a
`random variable x. if for all e :- 0.
`
`Pflxn—xlav E}—>0
`
`for n —> 00. then the sequence x” tends to x in
`probability.
`
`the equilibrium state of a
`convergent state
`dynamic system described by a first order vector
`differential equation is said to be convergent if
`there exists a 5 = 8(a)). such that.
`
`H I (to) —x¢ ||< 5 = lim x(r) = xe
`f—Fm
`
`See also stable state.
`
`a generic term used in the area of
`converter
`power electronics to describe a rectifier. inverter.
`or other power electronic device that transforms
`electrical power from one frequency and voltage
`to another.
`
`(I) a fuzzy set that has a
`convex fuzzy set
`convex type of membership function.
`(2) a fuzzy set in which all cit-level sets are
`convex. See also a-level set.
`
`the mathematical operation
`convolution
`needed to determine the response of a system
`from its stimulus signal and its weighting func-
`tion. The convolution operation is denoted by the
`symbol “at." The convolution of two continuous
`time signals f; (r) and fg(r) is defined by
`
`fit!)*f2(1) =f fiififzit - TMT
`
`=f ft(1)f2(f - I'M? if flit}. fztf}
`
`o
`
`convergence in probability
`
`for some se—
`
`=0.t<0
`
`139
`
`0006
`
`0006
`
`

`

`doing so confirmed significant parts of Newton's
`work.
`
`the second-order operator. defined
`Laplacian
`in R" as v1 = azxaxf +
`+ airs}. The
`zero crossings of an image to which the Laplacian
`operator has been applied usually correspond to
`edges. as in such points a peak (trough) of the
`first derivative components can be found.
`
`cell with the radius of 5—35 km (such
`large cell
`as those found in Groupe Special Mobile sys-
`tems). See also cell.
`
`a disturbance for which the
`large disturbance
`equation for dynamic operation cannot be lin—
`earized for analysis.
`
`( 1) term usually
`large-scale integration (LSI)
`used to describe the level of integration at which
`entire integrated circuits can be placed on a single
`chip.
`(2) an integrated circuit made of hundreds to
`thousands of transistors.
`
`partitioned com-
`large-scale process (system)
`plex process (system) composed of several sub-
`processes (subsystems) that are either physically
`interconnected or must be considered jointly due
`to the nature of the control objectives.
`
`LASCR See light-activated silicon controlled
`rectifier
`
`acronym that stands for light amplifica-
`laser
`tion by stimulated emission of radiation. Usually
`refers to an oscillator rather than an amplifier;
`commonly also refers to similar systems that op-
`crate at non-optical frequencies or with nonelec-
`tromagnetic wave fields.
`
`usually refers to a medium that
`laser amplifier
`amplifies light by the process of stimulated emis-
`sion: sometimes refers to amplification of some
`other field (nonoptieal electromagnetic. phonon,
`
`latch
`
`exciton, neutrino. etc.) or some other process
`(nonlinear optics. Brillouin scattering, Raman
`scattering. ete.).
`
`systematic distribution of lasers
`laser array
`intended to provide more power than a single
`laser.
`
`laser beam localized electromagnetic field
`distribution produced by a laser.
`
`output power from a laser di-
`laser efficiency
`vided by the input power (sometimes the pump
`power into the laser medium and sometimes the
`wall—plug power).
`
`laser medium the material in a laser that emits
`
`light; it may be a gas. solid. or liquid.
`
`oscillator usually producing
`laser oscillator
`an Optical frequency output and usually based on
`amplification by stimulated emission in a reso—
`nant cavity.
`
`laser pumping mechanism for obtaining a
`population inversion in a laser medium; the use
`of a laser beam to pump another laser.
`
`laser threshold
`
`the condition under which the
`
`round—trip gain in a laser i 5 equal to the round-trip
`loss.
`
`a time—dependent laser behav-
`laser transient
`ior such as mode-locking. loss switching. spon~
`taneous pulsations. relaxation oscillations.
`
`laser transition
`
`transition in a medium that
`
`has the capability of exhibiting more stimulated
`emission than absorption or spontaneous emis-
`sion.
`
`last-in-first-out (LIFO)
`
`See first-in-last-out.
`
`temporary holding cell for a
`a small
`latch
`value. the value on the input wires is buffered
`
`361
`
`0007
`
`0007
`
`

`

`limiter
`
`an equipment or circuit that has a func-
`limiter
`tion to keep output power constant. It can also be
`used to protect other circuits not to be overdriven.
`
`for an imaging
`limiting spatial resolution
`photodctector,
`the maximum number of black
`and white bar pairs of equal width and spacing
`that can be resolved per unit length. usually given
`in units of line-pairs per millimeter.
`
`Linde—Buzo—Gray (LBG) algorithm an al-
`gorithm for vector quantizer design. due to Y.
`Linde. A. Buzo and R. M. Gray (1980). The pro«
`cedure is based on the principles of the general-
`ized Lloyd algorithm and the K-means clustering
`algorithm.
`
`(I) on a bus structure, one wire of the bus.
`line
`which may be used for transmitting a datum. a
`bit of an address, or a control signal.
`{2) in a cache, a group of words from succes-
`sive locations in memory stored in cache mem-
`ory together with an associated tag, which con-
`tains the starting memory reference address for
`the group.
`(3) a power-carrying conductor or group of
`conductors.
`
`nonzero spectral width of an
`line broadening
`absorbing or emitting transition; caused by many
`physical effects.
`
`line code modification of the source symbol
`stream in adigital communication system to con-
`trol the statistics of the encoded symbol stream
`for purposes of avoiding the occurrence of sym-
`bol errors that may arise due to limitations of
`practical modulation and demodulation circuitry.
`Also called recording codes or modulation codes.
`
`for the impedance drop in the circuit between the
`device and the load center.
`
`split rubber tubing which is applied
`line hose
`over energized electric conductors as temporary
`insulation to protect nearby workers.
`
`line impedance stabilization network (LISN)
`a network designed to present a defined
`impedance at high frequency to a device under
`test,
`to filter any existing noise on the power
`mains, and to provide a 5042 impedance to the
`noise receiver.
`
`the shortest possible
`line of sight (LOS)
`straight line that can be envisioned. regardleSS of
`possible obstacles in the way. between a transmit-
`ter and a receiver. If a line of sight between trans—
`mitter and receiver is not blocked. the strongest
`signal will be received from the line-of-sight di—
`rection.
`
`a ratio used
`line outage distribution factor
`in contingency analysis. Given two parallel lines
`in a power system called it and y, assume that
`line y is removed from service. The line outage
`distribution factor of line it for the outage of line
`y is the ratio of the change in power flow on line
`it to the flow on line y before the outage.
`
`line rate
`
`See horizontal rate.
`
`shape of the spectrum of
`line shape function
`an emission or absorption line.
`
`a fault on a three phase power
`line to line fault
`line in which two conductors have become con-
`nected.
`
`line conditioner
`
`See power conditioner.
`
`a multiply-tapped au-
`line drop compensator
`totransformer equipped with a load-sensing relay
`which will adjust the line voltage to compensate
`
`line width width of the spectrum of an emis-
`sion or absorption line: often full width at half
`maximum. but other definitions also used.
`
`line-connected reactor
`
`See shunt reactor.
`
`368
`
`0008
`
`0008
`
`

`

`mlcro shadowing
`
`lized to overcome the effect of multipath fading.
`Compare with macro diversity
`
`shadowing due to both the
`micro shadowing
`orientation with respect to transmitter and re-
`ceiver. See also macro shadowing.
`
`a control technique — also
`micro-stepping
`called mini-stepping — that results in a finer po-
`sitioning resolution than can be obtained with
`simple ontoff control of the phase currents of a
`stepper motor. The practical implementation of
`micro-stepping requires the accurate and contin-
`uous control of all the phase currents of the step
`motor.
`
`sharp curvatures involving 10—
`microbending
`cal fiber axis displacements of a few micrometers
`and spatial wavelengths of a few millimeters. Mi-
`crobending causes significant losses.
`
`a low-power radio network that
`microcell
`transmits its signal over a confined distance.
`
`a high-frequency planar
`microcharmel diode
`monolithic Schottky barrier diode stmcture fab-
`ricated with micromachining that has very small
`parasitics and is used as a millimeter or submit—
`limeter wave mixer or harmonic multiplier.
`
`light modulator
`microchannel-plate spatial
`(MSLM)
`an optically addressed spatial light
`modulator. When input light is incident onto a
`photocathode on the write-in side of the MSLM.
`a photoelectron image is formed, which is mul-
`tiplied to about hundred thousand times by the
`microchannel plate. The resulting charge pattern
`will in turn affect the second layer. which is the
`LiNb03 crystal plate having electro-optic effect.
`The refractive index of the crystal plate is now
`modulated by the electric charge pattern. When
`output light passes through the crystal plate. the
`phase of output light is modulated by the vary-
`ing refractive index of the crystal plate. Since
`the LiNb03 is birefringence, phase modulation
`
`410
`
`becomes polarization modulation. Polarization
`modulation is visualized as intensity variation us-
`ing a polarizer. The generation of electric charge
`and its effect to the crystal layer are nonlinear.
`Their combined effect has thresholding capabil-
`ity that can be utilized for constructing optical
`logic gates.
`
`microchannel-plate spatial light modulator
`logic gate an optical logic gate utilizing thresh-
`olding capability of a microchannel-plate Spatial
`tight modulator (MSLM).
`
`a collection of low-level operations
`microcode
`that are executed as a result of a single instruction
`being issued.
`
`field specifying
`an n-bit
`microcommand
`some action within the control structure of a
`
`CPU. such as a gate open or closed, function en-
`abled or not. control path active or not. etc.
`
`21 computer whose CPU is a
`microcomputer
`microprocessor chip. and its memory and llO in-
`terface are LS] or VLSI chips.
`
`an integrated circuit chip that
`microcootroller
`is designed primarily for control systems and
`products. In addition to a CPU, a microcontroller
`typically includes memory. timing circuits. and
`U0 circuitry. The reason for this is to permit the
`realization of a controller with a minimal quantity
`of chips. thus achieving maximal possible mini-
`tuarization. This in turn, will reduce the volume
`and the cost of the controller. The microcon-
`
`troller is normally not used for general-purpose
`computation as is a microprocessor.
`
`microelectromechanical system (MEMS)
`micrometer-scale devices fabricated as discrete
`
`devices or in large arrays using integrated cir-
`cuit fabrication techniques. Movable compact
`micromechanical or optomechanical structures
`and microactivators made using batch process-
`ing techniques.
`
`0009
`
`0009
`
`

`

`microelectromechanical system (MEMS) for
`microwave
`a new multidisciplinary technol-
`ogy field with enormous potential for various
`applications, including microwave. MEMS are
`fabricated by integrated circuit processing meth»
`ads and commonly include sensors and actuators
`with physical dimensions of less than 1 mm on a
`side.
`
`the set of microcommands
`microinstruction
`to be executed or not. enabled or not. Each field
`of a microinstruction is a microcommand.
`
`lithography involving the
`micmlithography
`printing of very small features. typically on the
`order of micrometers or below in size.
`
`a fabrication process that uses
`micromachine
`integrated circuit fabrication techniques such as
`diffusion, oxidation. wet and dry etching to re-
`alize mechanical and electrical structures such
`
`as resonators. membranes. cavities, waveguide
`structures and a variety of thermal. medical. and
`chemical transducers.
`
`micromemory
`
`See control memory.
`
`a device that converts acoustical
`microphone
`signals into electrical signals.
`
`microprocessor
`VLSI chip.
`
`a CPU realized on an LSI or
`
`microprogram a set of microcode associated
`with the execution of a program.
`
`the practice of writing
`microprogramming
`microcode for a set of microinstructions.
`
`a sensor that is fabricated using
`microsensor
`integrated circuit and micromachining technolo-
`gies.
`
`a transmission line formed by a
`mierostrip
`printed conductor on top of a conductive-backed
`
`microwave transition analyzer
`
`it is often used in high-frequency.
`dielectric.
`printed circuit board applications.
`
`a radiating element con-
`microstrip antenna
`sisting of a conducting patch formed on the sur-
`face of a dielectric slab. which in turn lies on
`a ground plane. Microstrip antennas are usu-
`ally printed on circuit boards and fed by mi-
`crostriplines etched on the same board. Also
`called microstrip patch antenna.
`
`microstrip patch antenna
`tenna.
`
`See microstrip an-
`
`microtiming diagram a graphical display
`showing how the waveforms vary with time but
`with a time scale that has sufficient resolution to
`
`display clearly the delays introduced by the indi-
`vidual basic elements of the digital circuit.
`
`term used to refer to a radio signal
`microwave
`at a very high frequency. One broad definition
`gives the microwave frequency range as that from
`300 MHZ to 300 GHz.
`
`a specially de-
`microwave coplanar probe
`signed test probe for measuring devices from DC
`to microwave frequencies using a wafer probe
`statiou. The probe tip is constructed using copla-
`nar waveguide to present a highly controlled
`impedance (usually 50 ohms) to a device under
`test.
`
`the engineering of
`microwave engineering
`devices in the frequency range from 1 GHz
`to 1000 GB: corresponding to the wavelengths
`from 30 cm down to 0.3 mm.
`
`a device that
`microwave transition analyzer
`can combine the functionality of several dedi-
`cated measurement instruments.
`It is a pulsed
`RF measurement system that operates in the time
`domain like a high frequency sampling oseillo-
`scope. Using the fast Fourier transform. the in-
`formation can be converted into frequency do-
`
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`

`Raman scatter
`
`frequency-shifted light scat—
`Raman scatter
`ter. utilized as powerful analytical chemistry
`technique.
`
`light by
`scattering of
`Raman scattering
`means of its interactions with the vibrational re—
`
`sponse of a molecular system. The scattered
`light
`is typically shifted to lower frequencies
`(See Stokes law); the frequency shift is equal to
`the vibrational frequency of the molecule. typi-
`cally lDl3 to 1014 Hz.
`in spontaneous Raman
`scattering (See spontaneous light scattering). the
`scattered light is emitted in nearly all directions.
`In stimulated Raman scattering (See stimulated
`light scattering). the scattered light is emitted in
`the form of an intense beam. The emitted beam
`
`tends to be intense because it experiences large
`amplification by an amount given by e3 l L. where
`g is the gain factor of stimulated Raman scatter-
`ing. 1 is the intensity of the incident laser beam
`in units of power per unit area, and L is the length
`of the interaction region.
`
`Ramon, Sir Chandrasekhara Venkata
`(1888—
`1970) author of 500 articles and independent in-
`vestigator of light scatter and acoustics. Winner
`ofa Nobel Prize for the discovery of Raman scat-
`teri ng.
`
`in acousto-optics.
`Roman—Natl! diffraction
`the regime where many diffraction orders exist
`due to the thinness of the acoustic grating rela-
`tive to the acoustic wavelength in the direction of
`light.
`
`regime
`Ramart—Nath diffraction regime
`where the acoustic beam width is sufficiently nar-
`row to produce many diffracted beams with sig-
`nificant power.
`
`Raman—Nath mode acousto-optic spectrum
`analyzer
`similar to the acousto—optic (A0)
`Bragg—mode spectrum analyzer, but uses illumi-
`nation at normal incidence to the face of the A0
`
`cell that results in multiple diffracted orders, with
`
`528
`
`the two first order beams being used at the Fourier
`plane to obtain the input RF signal spectrum.
`
`the scattering of
`Raman—Nath scattering
`light from a periodically varying refractive index
`variation in a thin medium, as contrasted with
`Bragg scattering, for instance in the operation of
`an acousto-optic modulator.
`
`:1 linear function of grey level. usually
`ramp
`connecting two contrasting regions. Named after
`its appearance in one dimension, it is often used
`as one model of an edge.
`
`the spectral feature generated
`Ramsey fringe
`when a quantum mechanical transition is excited
`by two identical-frequency, time-separated elec-
`tromagnetic pulses. Ramsey fringes are used in
`cesium atomic beam clocks.
`
`(1) term describing a type of
`random access
`memory in which the access time to any cell is
`uniform.
`
`(2) a method for allowing multiple users to
`access a shared channel in which transmissions
`
`are not coordinated {or perhaps are partially co—
`ordinated) in time or frequency.
`
`random access device
`
`See random access.
`
`direct—
`random access memory (RAM)
`access read/write storage in which each address—
`able unit has a unique hardwired addressing
`mechanism. The time to access a randomly se—
`lected location is constant and not dependent on
`its position or on any previous accesses. The
`RAM has a set ofk address lines {m = 2"}, n
`bidirectional data lines. and a set of additional
`lines to control the direction of the aceeSs (read
`or write), operation and timing of the device.
`RAM is commonly used for the main mem-
`ory of a computer and is said to be static if
`power has to be constantly maintained in order
`to store data and dynamic if periodic absences
`of power do not cause a loss of data. RAM is
`
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`
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`
`

`

`usually volatile. See also static random—access
`memory, dynamic random-access memory, non-
`volatile random-access memory.
`
`resprmse without a spectral
`random behavior
`or amplitude pattern or relationship to the exci—
`tation. The excitation may be internal, and may
`be thermal in nature.
`
`coding technique in which
`random coding
`codewords are chosen at random according to
`some distribution on the codeword symbols.
`Commonly a tool used in the development of in—
`formation theoretic expressions.
`
`3 digital system constructed
`random logic
`with logic gates and flip~flops and other baw
`sic logic components interconnected in an noun
`specific manner. See also microprogramming.
`
`random replacement algorithm in a cache
`or a paging system, an algorithm that chooses
`the line or page in a random manner. A pseudo-
`random number generators may be used to make
`the selection. or other approximate method. The
`algorithm is not very commonly used, though
`it was used in the translation buffers of the
`
`VAX] 1.3780 and the Intel i860 RISC processor.
`
`a signal Xtr) that is either
`random signal
`noise NU}, an interfering signal sit]. or a sum
`of these:
`
`Xtt) = .ntr)+‘ -‘+.vmtr)+N|(r)+»H+N,.(r)
`
`the process of testing using a
`random testing
`set of pseudo—randomly generated patterns.
`
`random variable
`
`a continuous or discrete val—
`
`ued variable that maps the set of all outcomes
`of an experiment into the real line (or complex
`plane}. Because the outcomes of an experiment
`are inherently random. the final value of the vari-
`able cannot be predetermined.
`
`raster coordinates
`
`an image in which the intensity
`range image
`ol~ point x is a function of the distance between x
`and the corresponding point in the scene (object)
`projected on the image plane.
`
`denoted J. it is defined
`range of Jacobian
`as a subSpacc RU) in R’ of the end—effector—
`velocities that can be generated by the joint ve—
`locities, in the given manipulator posture. See
`full rank Jacohian.
`
`one of the rare gases specified in the
`rare gas
`periodic table. He. Ne. Ar. Kr. Xe.
`
`exeimcr molecule formed by
`rare gas halides
`a reaction of a rare gas atom and a halogen atom:
`e.g.. XeF, ArF, KrF.
`
`excimer molecule formed
`rare gas molecule
`by a reaction of an excited and a neutral rare gas
`atom, usually with a third atom present. For ex—
`ample, Ara. Krz.
`
`an excimer molecule formed
`rare gas oxides
`by the reaction of a rare gas atom and an oxygen
`atom.
`
`a magnet that has any of
`rare-earth magnet
`the rare-earth elements in its composition. Typi~
`cally stronger than other magnet materials. these
`include neodymium iron boron and samarium
`cobalt.
`
`rare-earth permanent magnet magnet made
`of compounds of iron. nickel, and cobalt with
`one or more of the rare-earth elements such as
`
`samarium. These materials combine the high
`residual flux density of the alnico—type materi-
`als with greater coercivity than ferrites.
`
`a predetermined pattern of Scanning
`raster
`lines used to provitlc uniform coverage of the
`area used for displaying a television picture.
`
`raster coordinates
`
`coordinates in a display
`
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`
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`
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`
`

`

`used to maintain proper conditions of the cooling
`liquid for a power vacuum tube.
`
`dressing method in which the memory address
`of the data to be accessed or stored is found in a
`
`general purpose register.
`
`regular controllablllty
`
`a method for extracting
`regenerative braking
`kinetic energy from the load. converting it back
`to electricity. and returning it to the supply. Used
`widely in electric train drives and electric vehi-
`ales.
`
`the set of
`region of absolute convergence
`complex numbers s for which the magnitude of
`the Laplace transform integral is finite. The re-
`gion can be expressed as
`
`0+ < Re(s) 4: or_
`
`where a... and a; denote real parameters that are
`related to the causal and anticausal components.
`respectively. of the signal whose Laplace trans-
`form is be