JAOMAD Glossary A:
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Intro
A—Means "Analysis" when used in first alpha character position of ISA instrument function tag; means "Alarm" if in succeeding position [see ANSI/ISA S5.1-1984 (R1992)]; also: Availability of system or device, that is the proportion of time it will properly function and not fail [A=MTBF/(MTBF+MTTR)]
a—(Alpha) average percent change in resistance per degree of pure metal resistance device between 0°C and 100°C, usually designated by Greek letter alpha, with units of W/W/°C; also: new products undergo alpha testing as first step in getting user feedback, alpha being Latin for "doesn't work," J see Beta.
Å—Angstrom; ten to minus tenth meters (10-10) or one millimicron; unit used to define wavelength of light.
@—Commercial at, which is official name given to this symbol in international standard character sets; currently used in all cultures as separator in e-mail addresses on Internet; had earlier northern European meaning in accounts or invoices to give unit price of something “at the cost of;” use in business actually goes back to late medieval times as either unit of weight or of volume, representing one amphora, a measure that was based on capacity of standard terracotta jars that were then employed to transport grain and liquid about the Mediterranean (one thirtieth of a barrel).
A/B Roll—In video development, process that uses two sources whose content is mixed during edit to create dissolve, wipe, or effect; see B Roll.
ABC—Activity Based Costing.
ABEND—ABnormal END; also called a "crash" or "bomb," which occurs when computer is presented with instructions or data it cannot recognize or program is reaching beyond its protective boundary; result of erroneous software logic or hardware failure; if program is running under single-task (one program at a time) operating system, such as DOS, computer locks up and has to be rebooted whereas multitasking operating systems with memory protection halt offending program allowing remaining programs to continue; John C. Dvorak, a contributing editor of PC Magazine, estimates that MS Windows has 30 billion crashes each day, based on comments Bill Gates made at meeting for analysts in 2003 where he said that 5 percent of Windows machines crash, on average, twice daily.
ABI—Applied Binary Interface, to run without porting.
ABS—Aerylonitrile Butadiene Styrene; frequently used for enclosures; good high temperature resistance w/ high impact strength and cold temperature impact, good overall chemical resistance, can be adversely affected by ultraviolet; also: (American Bureau of Shipping); creates standards to which equipment must comply to be placed on ships of American registry.
Absolute Pressure—Gauge pressure plus atmospheric pressure; total force per unit area exerted by fluid.
Absorption—In fiber optic cable, loss of power from conversion of optical energy into heat; usually caused by impurities such as transition metals and hydroxyl ions.
AC—Alternating Current; electric current that reverses its direction at regularly recurring intervals, such as 60 times/second (60 Hz).
Accelerators—Used by some computer applications in creating keyboard alternatives to using screen menus for selecting choices; keystroke has special meaning within that particular application, saving more involved, but usually more “user friendly” procedures to make request or entry.
Acceptance Angle—In fiber optic cable, half angle of cone within which incident light is totally internally reflected by fiber core.
Acceptance Test—Series of tests used to demonstrate capabilities and workability of new system; usually conducted by manufacturer to show customer that system is in working order.
Access—As verb in computers, usually act of locating, and obtaining or placing data.
Access Code—Group of alphanumeric characters which identifies user to system so that information can be placed or retrieved by other devices in system.
Access Line—Portion of leased communication line, such as with telephone system, that permanently connects user with the serving central office or wire center.
Access Protocol—In digital communication, method by which devices on network are able to take turns to exchange data.
Access Time—Time computer system takes to locate and transfer data to or from storage.
Accessible—In process operation, term applied to device or function that can be used or seen by operator for purpose of performing control actions in process, such as set point changes, auto-manual transfer, ON-OFF actions from front of control panel, or equivalent on video screen.
Accessory—Peripheral device supporting main system function, such as floppy disk drive or printer.
Accuracy—Degree of conformity of indicated value to recognized accepted standard value, or ideal value; maximum error between the true value and the indicated value; see also Resolution and Precision; in controllers, comparison of actual output signal of device to true value of input, with various errors (such as linearity, hysteresis, repeatability and temperature shift) attributing to accuracy of specific device usually expressed as percent of full scale output (Span)
Accuracy Rating—Number or quantity that defines limit that errors will not exceed when device or system is used under specified operating conditions.
ACEA—Advisory Committee on Environmental Aspects; IEC term.
ACE—Advanced Computing Environment initiative; alliance of more than 20 firms who support software standards for Mips architecture based on common ABI and API; also: Asynchronous Communications Elements.
ACEC—Advisory Committee on Electromagnetic Compatibility; IEC term.
ACET—Advisory Committee on Electronics and Telecommunications; IEC term.
ACF—Actual Cubic Feet.
ACIM—Alternating Current Induction Motor.
ACK—ACKnowledge; control code of received transmission; also: sequence of operator action(s) which recognizes new alarm.
ACOS—Advisory Committee on Safety; IEC term.
Acoustic Coupler—Device which converts electrical signals into audio signals, enabling data to be transmitted over public telephone network through conventional handset.
ACPDP—Alternating Current Plasma Display Panel; see definition.
ACR—Automatic Cartridge Recorder; also: Attenuation-to-Crosstalk Ratio (of signal cable).
Acronymcompoop—Person who overuse acronyms. J
ACSE—Association Control Service Element; for ISO layer 7, for MAP 3.0.
ACT—Acoustic Charge Transport; technology that processes signals in their natural analog domain, taking advantage of 10,000 to 1 simplification that results when using analog rather than digital circuits; converts analog input signal into discrete-time signal, sampled in time, not quantitized in amplitude.
ACTFEL—Alternating-Current Thin-Film ElectroLuminescent; type of Liquid Crystal Display (LCD) flat panel display device; see Electroluminescent Devices.
Active Application—Computer application which currently has keyboard focus, in windows environment, usually “top” window which is “open.”
Active Device—Any component, device, or circuit which introduces gain or has functional direction; usually considered any device except pure capacitance, inductance, resistance, or combinations of these; in current loop applications, device capable of supplying current for loop.
Active-Matrix Displays (AMLCDs)—Liquid Crystal Display (LCD) technique where pixels on screen are controlled by voltage signals applied in rows and columns, and array of thin film transistors (TFTs), with one per pixel, keep the pixels energized at all times with no need to reenergize on each scan; thus they respond faster and are brighter than PMLCDs; compare with Passive-Matrix Displays.
Active-Matrix Organic Light Emitting Diode—The 'active-matrix' part refers to the driving electronics, or the Thin Film Transistor (TFT) layer; image actually displays it line by line (sequentially) but only changes one line at a time; uses a TFT which contains a storage capacitor which maintains the line pixel states, and so enables large size (and large resolution) displays.
Active Server Page—HTML page that includes one or more scripts (small embedded programs) that are processed on a Microsoft® Web server before the page is sent to the user.
ActiveX—Active component eXtension; object-oriented programming language; binary reusable software object (COM component) that plugs into Object Linking and Embedding (OLE) software, which allows different software packages to communicate, interacting with one another in networked environment making plant floor integration through Internet and intranets; since advent of Internet, Microsoft® has preferred to use this term over “OLE” because of expanded scope (and flashier marketing); their interface requirements were reduced to speed up downloading from slow-speed Internet connections; see COM, OSX, VBX.
Activity Based Costing—Information system which maintains and reports data on activities, products, and processes of plant or company.
Actuator—Generally an energy converter to provide physical action; in disk drive, it is mechanism that moves read/write head to desired position over disk drive; in process control valves it is device that converts controller output signal to valve stem position; in electrical switching devices, it is mechanism of switch or switch enclosure which operates the contacts.
ACU—Automatic Calling Unit; Dialing device which permits business machine to automatically dial calls over communications network (auto answer/dial modem).
A/D—Analog to Digital conversion of signal.
Ada—Computer language named after Ada Augusta, countess of Lovelace, assistant to Charles Babbage; based on Pascal, it was created under contract to U.S.Dept. of Defense for weapons system tracking, but since used throughout federal government for applications way beyond this purpose.
Adapter—Device that allows compatibility between different equipment.
Adaptive Control, Adaptive Tuning—Continuously adjusting gain (proportioning action) of control loop from signal external to that loop; sometimes other parameters are (also) modified, particularly integral (reset action); also: when referring to advanced control techniques, has come to mean broader definition for system of advanced process control that is capable of automatically adjusting (adapting) itself to meet desired output despite shifting control objectives and process conditions or unmodeled uncertainties in process dynamics, often performed through neural networks and/or fuzzy logic coupled with traditional PID type algorithms.
Adaptive Dithering—Form of graphic dithering in which program looks to overall image to determine best set of colors or shape when displaying that graphic on a system with different size palette than that on which it was created..
Adaptive System—System displaying ability to learn, change state, or otherwise react to stimulus; capable of adapting itself to changes in its own environment.
ADC—Analog to Digital Converter; also: Automated Data Collection.
ADCCP—Advanced Data Communications Control Procedures; bit-oriented communication protocol standard defined by ANSI.
Add-on—Component or device added to system to increase storage capacity, modify architecture, or upgrade performance; this capability is one of the powerful benefits of good distributed control system.
Additive Primaries—In color reproduction, red, green and blue; when lights of these colors are added together, they produce sensation of white light.
Additive Manufacturing—3D printing process of making a three-dimensional solid object of virtually any shape from a digital model; 3D printing is achieved using an additive process, where successive layers of materiel are laid down in different shapes different techniques include Digital Light Processing (DLP), Direct Metal Laser Sintering (DMLS), Electron Beam Melting (EBM), Fused Disposition Modeling (FDM), Fused Filament Fabrication (FFF), Laminated Object Manufacturing (LOM), Selective Heat Sintering (SHS), Selective Laser Melting (SLM), Selective Laser Sintering (SLS), StereoLithogrAphy (SLA).
Address—Identification of location in memory; number, label, or name that represents hardware or memory location within system, for convenience of obtaining access of data residing there for use in other parts of that system.
Adminisphere—Rarefied organizational layers beginning just above the rank and file; decisions that fall from the adminisphere are often profoundly inappropriate or irrelevant to the problems they were designed to solve. J
Administratium—Heaviest element known to science which is chemically inert because it has no protons or electrons, and thus an atomic number of zero; nevertheless, it does have 1 neutron, 75 vice-neutrons, and 111 assistant vice-neutrons, all held together by meson-like forces called morons. J
ADO—Ampex Digital Optical, in video development, traditional video editing system component that allows for video frames to appear in motion.
ADPCM—Adaptive Differential Pulse Code Modulation; encoding format for compressing and storing audio information in digital format.
ADS—Address Data Strobe.
ADSL—Asymmetric Digital Subscriber Line; technique that compresses amount of data needed to send computer, voice, and video over normal phone lines (vs. coax) so that those three services can function independently and simultaneously; the asymmetrical component means that upload speeds are slower than download speeds, but most delays are during downloading; see also SDSL.
Advanced Design—Beyond comprehension of the sales force. J
Advanced Control—Process control strategies beyond PID loop control such as neural networks and fuzzy logic, but defined by some to include feedforward, dead-time compensation, lead/lag, adaptive gain which other refer to as APC (below).
Advanced Metering Infrastructure (AMI)—Systems that measure, collect, and analyze energy usage, from advanced devices such as electricity meters, gas meters, and/or water meters, through various communication media (typically SCADA) on request or on a pre-defined schedule; includes hardware, software, communications, customer associated systems and meter data management (MDM) software.
Advanced Persistent Threat (APT)—refers to advanced and normally clandestine means to gain continual, persistent intelligence on an individual, or group of individuals such as a foreign nation state government; term more commonly thought of as being an article of the computer era, but it has existed since the realization of the benefits of intelligence gathering and long before the invention of the computer or internet.
Advanced Process Control (APC)—Process control strategies beyond straightforward PID loop control, usually defined as "classical" advanced control, involving combination of PID loops, dead time compensators, lead/lag feedforward function blocks and single variable constraint controllers.
AE—Application Entity; active element within an ISO layer; also: Architectural Engineer; also: Application Enabler.
A&E—Architecture & Engineering; company which designs and builds process plant; now often called EPC.
AEB—(Australian Electrotechnical Board); Standards Association of Australia, member of IEC.
AEC—Architect, Engineer & Constructor firm; see EPC.
AECMA—(Association Européenne des Constructeurs de Matériel Aérospatial).
AEGIS—Abnormal Event Guidence Information System.
AENOR—(Asociación Española de Normalización y Certificación); standards group in Spain.
AES—Advanced Encryption Standard; NIST-standard cryptographic cipher that uses a block length of 128 bits and key lengths of 128, 192 or 256 bits.
AES-CCMP—AES-Counter Mode CBC-MAC Protocol; encryption algorithm used in 802.11i security protocol using AES block cipher, but restricts key length to 128 bits; incorporates two sophisticated cryptographic techniques (counter mode and CBC-MAC) and adapts them to Ethernet frames to provide a robust security protocol between the mobile client and the access point.
AFAN—Advanced Factory Automation Network.
AFM—Audio Frequency Modulated.
AFNOR—(Association Française de Normalisation); standards group in France.
AGA—Advanced Graphics Architecture; Chipset for driving high resolution multimedia tools; also: (American Gas Association) national trade association founded in 1918 in U.S., composed of about 300 gas distribution and transmission companies to act as clearinghouse on gas energy information, and act as catalyst in technical and energy policy matters as well as voice for gas industry.
AGC—Automatic Guidence Control.
Agent—Computing program performing some information gathering or processing task in background, usually very small well-defined task; some feel that human mind consists of thousands or millions of agents working in parallel, so “true” artificial intelligence machines should also contain many agents with some system to arbitrate among competing results of this activity.
Agile Manufacturing—Phrase coined by the Iacocca Institute at Lehigh University to describe manufacturing enterprise in which “information flows seamlessly among inventory, sales, and research departments as well as between organization and its suppliers and customers;” work within agile organization occurs concurrently rather than sequentially.
AGP—Accelerated Graphics port; provides capability for 3 dimension and full-motion video graphics in workstations.
A-GPS—Assisted Global Positioning System; uses a network-located server to shorten time to location fix.
Aggregation—In object oriented software, combination of objects which are not necessarily contained, but are used directly, without modification.
AGVS—Automated Guided Vehicle System; controls vehicles that proceed along predetermined routes or guide-paths, performing scheduled material handling tasks without operators.
AHP—Analytical Hierarchy Process; approach to using multiple criteria in decisions which helps meaningful organization of information, provides ability to easily change weights and ratings for “what if” analysis, and verify approach to evaluation is logical and consistent.
AI—Artificial Intelligence; see definition; also: Automatic Identification.
AIA—Application Integration Architecture; Digital Equipment Corp. method of allowing programs to be portable between VMS and ULTRIX.
AIFF—Audio Interchange File Format; method of saving digital audio in electronic memory, used for exchanging data between computers; developed by Apple and used in Macintosh with compression standard called Macintosh Audio Compression/Expansion (MACE).
Air Compressor—Machine that takes energy produced in a coal-burning power plant 200 miles away and transforms it into compressed air that travels by hose to a Chicago Pneumatic impact wrench that grips rusty bolts which were last over tightened 30 years ago by someone at Ford, and instantly rounds off their heads; also used to quickly snap off lug nuts. J
Alarm—Warning signal presented whenever critical deviation state from normal conditions occur in process; technically, alarm is condition (not event), event is when alarm condition begins, another event is when that condition ends.
ALARP—As Low As Reasonably Practical; acceptable control system failure designation based upon IEC 1508 specification
ALE—Application Link Enabling; allows message exchange between different applications within or between computer systems.
ALGOL—ALGOrithmic Language; computer language designed by committee of Association for Computing Machinery and European computer industry representatives; useful for mathematical problem solving; first block oriented computer language.
Algorithm—In computers, prescribed set of well defined, unambiguous rules or processes for solution of problem in some finite number of steps.
Aliasing—In digital signal processing (DSP), distortion due to sampling continuous signal at too low a rate; see Nyquist Rate; also: in digital bitmapped graphics, jagged boundary along edges of shapes and different colored shapes within an image.
All New—Parts not interchangeable with existing models.J
Alpha Test—Trying out new product at vender's own company before subjecting it to beta test; software undergoes alpha testing as first step in getting user feedback …Alpha must be Latin for "doesn't work."J
Alphanumeric—Character set of type that contains both the letters of the alphabet and numerical digits; Sequencing or ordering of list using both initial letters and numbers.
Alternating Current Plasma Display Panel (ACPDP)—Type of Liquid Crystal Display (LCD) which relies upon emission of photons from gas that has been ionized by electric charge; electrodes covered insulation layers to protect from working gas and assuring longer life; compare with Direct Current Plasma Display Panel.
Alternating-Current Thin-Film ElectroLuminescent (ACTFEL)—Type of Liquid Crystal Display (LCD) flat panel display device; see Electroluminescent Devices.
ALU—Arithmetic/Logic Unit, which is portion of computer CPU that performs arithmetic and logic functions (rather than memory organization and data transfer functions).
Alumel™—Aluminum nickel alloy used in negative leg of type K thermocouple; trade name of Hoskins Manufacturing Company.
A/M—Auto/Manual switch; also: Auto/Manual station to provide process control signals.
AM—Amplitude Modulation; transmission technique in which amplitude of carrier is varied in accordance with signal, see PM & FSK; also: in electronic publishing and screen displays, halftone screening as opposed to FM screening, has dots of variable size with equal spacing between dot centers, see Halftone, compare with FM screening and Stochastic Screening.
AM/FM—Automated Mapping/Facility Management; electronic mapping, branch of GIS.
AM/PSK—Amplitude Modulation/Phase Shift Keying.
Ambient Compensation—Design of equipment or measuring instrument such that changes in ambient conditions do not affect performance of that equipment or readings of that instrument.
Ambient Conditions—Environment surrounding equipment or system, such as humidity, temperature, pressure, vibration, shock, magnetic fields, etc.
AMI—Advanced Metering Infrastructure; see definition.
AMLCD—Active Matrix Liquid Crystal Display; see definition.
AMOLED—Active-Matrix Organic Light Emitting Diode, see definition.
Ampere—(Amp) unit of measure used to define rate of flow of electricity (current) in a circuit; one coulomb (6.25x108 electrons)/second.
Ampersand (&)—In typographical composition of screen displays and printing, symbol for Latin word "et," meaning "and."
Amplifier—Device that produces output which is function directly corresponding to input, but increases magnitude by drawing from an external source.
Amplitude—Height of alternating or oscillating signal.
Amplitude of Deviation—Total variation from desired setpoint of system; sometimes called closeness in control, expressed as "closeness of control is ±2°C" or system bandwidth of 4°C.
AMR—Automated Meter Reading.
Analog—Continuously varying (modulating) signal; in communications, transmission using variable and continuous waveforms to represent information values, where interpretation by receiver is approximation (quantification) of encoded value, compared with digital.
Analog Backup—Alternative method of process control by conventional analog instrumentation in event of failure in computer system.
Analog Circuit—Electrical circuit that provides information from a modulating electrical signal, such as a 4-20mA signal in instrumentation circuits.
Analog Control—Automatic process control loops using pneumatic, electro-mechanical, electrical, or electronic equipment; compare: Digital Control.
Analog Signal Processing—Processing signals completely within the analog domain; Contrast with DSP.
ANCE—(Asociacion Nacional de Normalizacion y Certificacion del Sector Electrico); standards and certification organization for electrical products in Mexico and grants NOM (Normas Oficiales Mexicanas) mark for products that are certified to the Mexican standard.
ANDF—Architecture-Neutral Distribution Format; an OSF/1 term.
Anemometer—An instrument for measuring and/or indicating velocity of air flow.
Angstrom—Ten to the minus tenth meters (10-10) or one millimicron; unit defining wave length of light; designated by symbol Å.
Angular Misalignment—In fiber optic cables, loss of optical power caused by deviation from optimum alignment of fiber to fiber at coupling.
Animation—Process of making object move across video screen by rapidly displaying series of pictures of it (icons), each in slightly different position.
ANN—Artificial Neural Network; see Neural Network.
Annotation—Comment, note or descriptive remark added to printout, screen view, or even in memory itself.
Annunciator—Visual or audible signaling device which indicates conditions of monitored points, loops, circuits, equipment, etc.
ANSI—(American National Standards Institute); nonprofit, independent organization supported by trade organizations, industry, and professional societies for standards development and coordination in USA; they represent USA to ISO; they defined ASCII.
ANSP—Advanced Networking Security Protocol.
Anti-aliasing—In digital graphics, technique for reducing jagged appearance of aliased bitmapped images, usually by inserting pixels that blend boundaries, especially color boundaries.
Anticipatory Control—In process control, sensing change in input of process to cause change in control signal to one of the other inputs to that same process, does not have self correcting action as with Closed Loop (Feedback) Control; also called Feedforward control or Open Loop Control.
Antihunt Circuit—Circuit designed to prevent oscillation in feedback process control loop, thereby stabilizing it.
Antireset Windup—Feature which can appear in three-mode (PID) process controller that prevents integral (auto reset) function from performing when process variable is outside proportional band.
AOD—Argon Oxygen Desulfirization
AOE—Application Operating Environment; design for UNIX® by AT&T®.
AOX—Adsorbable Organic Halides, a consideration in EPA (U.S.) regulations.
APC—Advanced Process Control; process control strategies beyond straightforward PID loop control, usually defined as "classical" advanced control, involving combination of PID loops, dead time compensators, lead/lag feedforward function blocks and single variable constraint controllers.
AP—Application Platform; part of software systems management services which provides environment for management application development, debugging, and execution.
APC—Advanced process Control.
APD—Avalanche PhotoDiode; diode that exhibits internal amplification of photocurrent through avalanche multiplication of carriers in junction region.
API—Application Program Interface; set of formalized software calls and routines that can be referenced by some application program to access underlying network services; programs that use API-compliant calls can communicate with any others that use that same API; interface between applications software and application platform.
APL—A Programming Language; computer language developed by Kenneth Iverson and used mainly in scientific applications; known for its scope compactness, and facility with arrays, it has highly specialized character set which can be mapped to keyboard.
APM—Asset Performance Management; see definition; also: Advanced Process Management.
APP—Application Portability Profile; developed by NIST, includes X windows, POSIX, SQL, Information Resource Dictionary System for database systems, Open Systems Interconnections, NFS, COBOL, C, Ada.
APPC—Advanced Peer-to-Peer Communications; network architecture definition by IBM® specified as featuring high-level program interaction capabilities on peer-to-peer basis.
APPLE—Arrogance Produces Profit-Losing Entity J.
Applets—Small software application packages for functions which are subsets of larger ones, such as spell-checking function within word processor application.
Application—Computer program, or group of programs used for a specific task, such as word processing.
Application Enabler—Software product which allows rapid development of software application through use of productivity tools, standard components, and reuse of previously developed software.
Application Filter (proxy)—Software security model that uses specialized applications to proxy (stand in) for IP services to protect private data communication network from untrusted network such as Internet.
Application Gateway—In computer based networks, security protection system designed to prevent unauthorized access through firewall technology which applies security mechanisms to specific applications, such as FTP and Telnet servers; very effective, but can impose a performance degradation; see Firewall Technology.
Application Layer—In digital communication, logical entity of OSI digital communication model; topmost of seven layers and that which interfaces with network user; performs network services like file transfer and e-mail.
Application Oriented Language—Problem-oriented programming technique which employs statements which resemble terminology of user, rather than those of programmer.
Application Program—Program developed to perform particular industry -specific activity, especially with interface to user that needs little or no special training.
Application Program Interface (API)—Set of formalized software calls and routines that can be referenced by an application program to access underlying network services; programs that use API-compliant calls can communicate with any others that use that API.
Application Service Provider—Business that provides computer-based services to customers over a network.
Application Software—Programs that process or manipulate data; such as database managers, word processors, text editors, spreadsheets, which are run by operating system of computer.
Application Specific Software—Computer program adapted or tailored to specific user requirements for purpose of data collection, data manipulation, data archiving, or process control.
APS—Advanced Planning & Scheduling.
APSU—Alarm Power Supply Unit.
APT—Advanced Persistent Threat; see definition; also: Automatically Programmed Tools; see definition.
APWA—(American Public Works Association); international educational and professional association of public agencies, private sector companies, and individuals founded in 1937 to providing high quality public works goods and services; maintains accreditation program called Continuing Education Units (CEUs).
Arc—Electric current through air or across surface of insulator associated with high voltage; can damage components.
Archie—Internet software tool for finding files stored on anonymous FTP sites; user needs to know exact file name or substring for them; there are over twelve hundred Archie servers on the Internet which allow someone to search through indexes of over two million files through text strings, keywords, file names, allowing search limiters and Boolean operators.
Architecture—Logical and physical structure (internal operations) of system.
Archival (Archive)—Long term storage of data, usually onto some auxiliary storage medium, such as separate disk or tape.
ARCnet®—Attached Resource Computer NETwork; token-passing network developed by Datapoint® in 1977 using active hub star at 2.5Mbs, specifies only bottom few layers of ISO model; combines token-passing scheme (each node takes turn with network access) with star, bus, or tree topologies rather than ring topology (such as token ring).
ARIN—(American Registry for Internet Numbers); the organization responsible for doling out IP addresses in North America.
Armature—Part of electromagnetic device that moves in response to magnetic forces; rotor of motor and moving portion of contracts are examples.
ARP—Address Resolution Protocol; TCP/IP process that maps Internet Protocol (IP) addresses to Ethernet addresses; required by TCP/IP for use with Ethernet.
ARPA—(Advanced Research Projects Agency); operates within U.S. Department of Defense which developed first major packet-switched digital computer network.
ARPANet—Advanced Research Projects Administration Network; precursor to Internet, developed in late ‘60s & early ‘70s by U.S. Department of Defense as experiment in wide area networking that could survive nuclear war.
ARQ—Automatic ReQuest for retransmission; in digital communications where receiver asks transmitter to resend block or frame, generally because of errors detected by receiver.
Artifact—In video development, area within image or characteristic of image that is result of system limitation, for example, weird shimmering, jaggies, or other undesirable distortion; also in digital graphics, image imperfections caused by data compression.
Artificial Intelligence—That branch of computing which involves capabilities resembling human thought processes, such as reasoning, learning, vision and aural recognition, and even self improvement; term coined in 1956 by John McCarthy at MIT
Artificial Language—Programming language based on prescribed set of rules established ahead of time, such as BASIC, COBOL, PASCAL, etc.
AS—Air Supply; also: Automation System.
ASA—(American Standards Association).
Ascender—In typography, that part of lower case letter rising above main body, as in characters "b" and "d."
ASCII—[pronounced: asky] (American Standard Code for Information Interchange); binary character code, each representing single computer character, to define 128 upper and lower case characters, numerals, punctuation, and special communication control characters; standard method of encoding characters into 7 or 8 binary bits, typically 7-bit-plus-parity code, representing alphanumeric data for processing and communication compatibility among various devices; defined in ANSI X3.4-1986, and normally for asynchronous transmission.
ASE—Application Service Element within an ISO layer.
ASHRAE—(American Society of Heating, Refrigerating, and Air Conditioning Engineers).
AS-i—Actuator Sensor Interface; European "fieldbus" for binary sensors and actuators.
ASIC—[pronounced: A-sick] Application Specific Integrated Circuit; custom designed chip designed for specific application rather than general-purpose chip such as microprocessor; used to improve performance over general-purpose CPUs, because ASICs are "hardwired" to do specific job and do not incur overhead of fetching and interpreting stored instructions.
ASM—Abnormal Situation Management.
ASN—Advanced Shipment Notice.
ASN.1—Abstract Syntax Notation One; ISO/IS 8824 & 8825 encoding and decoding structures of software.
ASP—Application Service Provider, see definition; also: Active Server Page, see definition; also: Analog Signal Processing, see definition; also: Average Selling Price.
ASPC—Algorithmic Statistical Process Control; closed loop version of normally open loop SPC.
ASQC—(American Society of Quality Control).
ASRS, AS/RS—Automated Storage and Retrieval System.
Assembler—Program that translates symbolic source code (written in assembly language) instructions into machine language instructions.
Assembly Language—Machine oriented computer programming language in which mnemonics instead of numeric instructions are used to represent each machine language instruction; low-level symbolic programming language closely resembling machine code; each CPU has its own specific assembly language.
& items of value owned by a person or business; in process plants this generally
refers to the Long Term Assets that are used to produce the product(s); primary
classifications of assets are:
Current Assets: cash and other liquid instruments, including accounts receivable, that can be converted to cash within one year at maximum;
Long Term Assets: plants, equipment, real estate and other capital assets, net of depreciation;
Prepaid & Deferred Assets: expenditures for future costs or expenses, such as insurance, interest or rent, that are set up as assets to be amortized over an applicable period;
Intangible Assets: assets with a determined value, but which may not be scalable, such as goodwill, patents, copyrights, and brand name recognition.
Asset Management—Defined by some as utilization of information generated by smart field devices to improve maintenance and service life of process equipment and make positive contributions to operating efficiency; others go beyond this to include optimization activities of process, even of plant itself, and some, entire enterprise; see other terms: Enterprise Asset management, Physical Asset Management; Asset Performance Management.
Asset Performance Management (APM)—Methodology for operating process plants that combines the traditionally separate maintenance management and operations management software tools into a cohesive view, so assets are available when actually needed and their use can be managed effectively and controlled together as one system.
Assignable—In instrumentation, term applied to feature which permits channeling (or directing) of signal from one device to another without need for switching, patching, or changes in wiring.
programming language statement that gives value to some variable, such as in
x = x + 5, y = 8.
Assisted GPS (A-GPS) — Global Positioning System that uses a network-located server to shorten time to location fix.
Association—In communications, program-to-program logical relationship; may be dynamically established and torn down; may be assumed, may not be required; see Connection.
Associative Memory—Neural network architecture used in pattern recognition applications, in which network is used to associate data patterns with specific classes or categories it has already learned.
AST—Above ground Storage Tank.
Asterisk—Symbol often used in calculations to represent multiplication; also: used as general request in some computer search tools to mean all references in some particular category, such as “*”file = all files.
ASTM—(American Society for Testing and Materials); scientific and technical organization that develops material standards and testing methods.
ASU—Activated Sludge Unit.
Asymmetrical Compression—Data compression system that requires more processing capability to compress an image than to decompress an image; typically used for mass distribution of programs on media such as CD-ROM.
Asynchronous—Computer logic or communications in which all operations are triggered by free running signal, not related to specific frequency or clock timing; successive stages are triggered by completion of preceding stage; communications node that sed message without waiting for receiver to signal that it is ready to receive; also: in Open Applications Group specification, method of communications via separate responses instead of typing client session to some singular job.
ATA-2―(Fast ATA) provides faster transfer rates among computer devices and allows for multiple channels, each connecting two devices. See ATAPI.
ATAPI―AT Attachment Packet Interface; specification for IDE that supports non-hard disk devices for computers such as tape drives and CD-ROMs. See IDE.
ATC—Air To Close (pneumatic valve actuator, which will Fail Open)
ATE—Automatic Test Equipment.
ATEX—ATmospheric EXplosion regulation; directive that covers both electrical & mechanical equipment and protective systems, which may be used in areas endangered by potentially EXplosive ATmospheres created by presence of flammable gases, vapours, mists or dusts.
ATG—Automatic Tank Gauge(ing).
ATM—Asynchronous Transfer Mode; type of packet switching that transmits fixed length units of data, and being asynchronous, recurrence of cells does not depend on bit rate of transmission system, only source requirements (packets include address of their destinations); provides very fast and efficient transfer mode for multimedia applications (up to 10000 text pages per second), allowing, for example, real time video transfer and group-ware slide projection; also: ATMospheres; units of pressure measurement.
Atmospheric Pressure—Force exerted on unit area by weight of atmosphere.
ATO—Air To Open (pneumatic valve actuator, which will Fail Closed)
ATPG—Automatic Test Pattern Generator; used in video raster alignment.
ATRAC—Adaptive Transform Acoustic Coding; coding method to create minidisks using a varying number of bits per sample depending upon "critical' frequencies encountered.
ATS—Automatic Test System.
Attenuation—Decrease in strength of signal, measured in decibels, as it passes through control system, or transmission line; opposite of "gain."
Attribute—Characteristic quality of data type, data structure, element of data model, or system; in object oriented software, it is some piece of information that describes characteristic of object, such as size, color, etc.
Audio Frequencies- Frequencies which can be heard by human ear, usually between 15 cycles and 20,000 cps.
Audit log analysis—Generated for cyber security in computer systems, applications, infrastructure equipment, and most other IT hardware; some of the log entries will identify successful and failed intrusion attempts.
AUI—Attachment Unit Interface; twisted pair telephone wire IEEE standard for Ethernet.
Authentication Token—Separate security device carried by authorized users for using to log onto network, security "card" or "token" may be read directly like a credit card, or it may display a changing number that is typed in as password; see challenge/response.
Authoring Tools—Software capabilities which allow creation of applications without tedious details of programming.
Authoring System—Software that helps developers design interactive courseware easily, without painstaking detail of computer programming.
Auto-Answer—Modem that can automatically answer incoming telephone calls from computers and provide data to that system.
Auto-Dial—Modem capable of connecting to telephone system and dialing number; modem and communications software to perform proper procedures so that computers may exchange data.
Auto-PC—Auto Personal Computer, handheld or embedded Windows CE systems for specialized tasks in an organization, point-of-sale terminals, and navigation devices; see H/PC.
Auto-Restart—Capability to perform automatic initialization functions to resume operations following as equipment or power failure.
Auto-Tuning—Technique within controller which analyses change in setpoint of closed loop, or in control output of open loop, and adjusts or recommends tuning parameters based upon that analysis; change is necessary to allow tuner to learn magnitude and period of process response, which is used to calculate new parameters; see Self-Adaptive.
Auto/Manual Station—In instrumentation, synonym for Control Station.
Automatic—You cannot repair it yourself. J
Automatic Error Correction—Technique for detecting and correcting errors that occur in data transmission or data handling.
Automatically Programmed Tools (APT)—Computer aided part programming system for numerically controlled machine tools developed for multi-axis milling machines, and point-to-point and turning work.
Automatic Reset—Feature of ON/OFF limit controller that automatically resets that controller when controlled signal returns to within set limits of the bandwidth; also: integral (I) function on two mode (PI), or three mode (PID) controller which adjusts proportional bandwidth with respect to setpoint in response to change in process variable (due to change in load).
Automation—Using current technology (tools) to improve performance, quality, and cost of formerly manual operations.
Availability—Ratio of time that system is operating correctly to total hours of scheduled operation; Prior to 1962 was calculated as value of MTBF/(MTBF+MTTR), after 1962 defined by MIL spec. as MTTF/(MTTF+MTTR) [calculation of those times, not a tested value]; very much depends upon environmental conditions, MTBF will drop by about ½ for every 10°C increase, all other ambient factors will have similar impact.
Avalanche Photodiode—Diode that exhibits internal amplification of photocurrent through avalanche multiplication of carriers (electron hole pairs) in junction region.
AVI—Audio-Video Interleaved; digital file format by Microsoft® developed for dynamic graphics.
AWG—(American Wire Gauge); U.S. standard system used for designating size of electrical conductors; gauge numbers are inverse to size.
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