JAOMAD Glossary T:
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
T—Symbol of ANSI thermocouple type for Copper vs. Constantan; also: means "Temperature" when used in first alpha character position of ISA instrument function tag, means "Transmit" in succeeding position [see ANSI/ISA S5.1-1984 (R1992)]; also: T(uppercase) in math is abbreviation "tetra-" for 1012; also: Trap.
Table Saw—Large stationary power tool commonly used to launch wood projectiles for testing wall integrity. J
Tag, Tagname—In manufacturing, unit of information whose composition differs from that of other members of the set so that it can be used as marker or label; also: in process control, alphanumeric code which identifies each instrument device in a system; also: in SCADA system for power distribution, flag or icon on video screen which identifies that a person is working on a power line, which should prevent that line from being activated; also: in control system software, name assigned to some specific one variable in database of a device (HMI, controller, historian, etc.) sometimes called “point;” also: in computer programming, ACSII text indicators with which user surrounds text and images to designate certain formats or styles.
Tail Circuit—Feeder circuit or an access line to network node.
Talking Heads—In video development, term commonly applied to a video scene with no action; comes from commercial TV where scene shows only a person speaking or reporting.
Tap—In digital signal processing (DSP), circuit in digital filters that multiplies a coefficient by a data sample; also: in cable based LANs, connection to main transmission medium.
Tape—Recording media for data or computer programs such as "permanent' perforated paper tape or erasable magnetic tape; magnetic tape has had much higher storage capacity than disk storage, but requires much longer to search for writing or recovering data.
TAPPI—(Technical Association of the Pulp and Paper Industry) [U.S.].
Task—In computer operations, an executing application.
TB—TrackBall; also: Terminal Board; also: TeraByte, one trillion bytes; also: Transducer Block; see definition
TBC—Time Base Corrector; electronic device that corrects inconsistencies in the rhythm of a video signal.
TBMT—Transmitter Buffer eMpTy.
TBP—Transaction Based Payments.
TBT—Technical Barriers to Trade agreement.
T/C, TC—Thermocouple, see definition; also: Time Constant
TCB—Tension Control Bolt; type of alternative design fastener which has a splined end that extends beyond the threaded portion of the bolt and an annular groove between the threaded portion of the bolt and the splined end; a special wrench required to install these bolts has two coaxial chucks—an inner chuck that engages the splined end and an outer chuck that envelopes the nut where the two chucks turn opposite to one another to tighten the bolt; at some point, the torque developed by the friction between the nut and bolt threads and at the nut-washer interface equals the shear resistance of the bolt material at the annual groove causing the splined end of the bolt to shear off at the groove; if the system has been properly manufactured and calibrated, bolt pretension is achieved at this point, based on material strength, thread conditions, the diameter of the splined end, and the surface conditions at the nut-washer-joint interface.
TCD—Thermal Conductivity Detector.
TCF—Totally Chlorine Free; a consideration in EPA (U.S.) regulations.
Tcl/Tk - [pronounced: tickle or ticklet ] Tool Command Language/ToolKit; interpreted script language used to develop variety of applications, including GUIs, prototypes and CGI scripts; originally for UNIX, was later ported to PC & Macintosh; Safe-Tcl is an enhanced Tcl interpreter that provides secure, virus free environment; additionally provides an interface into compiled applications (C, C++, etc.) as a way to connect program modules together.
TCLP—Toxicity Characteristic Leaching Procedure; test required under Resource Conservation & Recovery Act (U.S.) to determine toxicity and characteristics of hazardous waste and potential for migration.
TCO—Total Cost of Ownership; more than selling price, includes cost of implementation, all services, maintenance, training and upgrades, and parts to keep system operational over its lifetime.
TCP—Transmission Control Protocol; layer 4 of ISO model.
TCP/IP—Transmission Control Protocol/Internet Protocol; originated by U.S. Department of Defense, this standard allows sharing of applications among different vendors' computing devices in high speed environment; corresponds to transport and network layers of OSI model; breaks data stream into packets (information blocks) and gives each an address & sequence number; IP gets packets from sender to receiver in shortest time possible; TCP manages flow and ensures data is correct; TCP/IP protocol defines Internet technologies.
TCT—Total Cycle Time.
TD—Means "Temperature Differential" when used in first two alpha character positions of ISA instrument function tag [see ANSI/ISA S5.1-1984 (R1992)].
TDEL—Thick Dielectric ElectroLuminescent; display media which produces bright, true-blue light using a more pure strontium sulfide and a combination thick-film and thin-film to improve brightness; has advantages over LCD including broader temperature range and wider viewing angle without fading or color loss across the whole spectrum.
TDM—Time Division Multiplexor, see definition; also: Test Data Management, see definition.
TDMA—Time Division Multiple Access; in digital communication, media access protocol (data link layer) using TDM, see above; high speed, burst mode of operation that can be used to interconnect LANs, first used as multiplexing technique on shared communication satellites, currently used as well in wireless technologies; triples the capacity of the original analog method (FDMA). It divides each channel into three subchannels providing service to three users instead of one; see FDMA, “rival” CDMA.
TDR—Time Domain Reflectometry; see definition; ; also: Time Delay Relay; also: Technical Data Requirement; also: Technical Design Review.
TD Ratio—TurnDown Ratio, see definition.
TDS—Total Dissolved Solids.
Technology—A "toolbox" of current applied science which can be used to develop automation (in our context here).
TEDS—Transducer Electronic Data Sheet; see definition.
Tee coupler—Three port optical or electrical coupler, often used on multidrop data highways (communication systems).
Telecommunications—Term encompassing both voice and data communications in form of coded signals over media.
Telecommuter—Person not physically located at work site but dialing into that location via computer.
Telemetry—Transmission of coded analog data, often real-time parameters from some remote site; today usually in digital formats.
Telenet—Part of TCP/IP suite supporting virtual terminals for remote log-on; one of the largest public data networks (PDNs) in the U.S.; Telenet is owned by U.S. Sprint Communications Corporation; competing network, called Tymnet, is owned by McDonnell Douglas; Telenet serves as communications backbone for many online services.
Telepresence—State of being present at a distance; for business it can enable teams who cannot be together to work together; it can also change relationship between company and its customers - past, present, and future - by inviting whole community of people interested in company together in a place… not a real place, but a virtual place on the internet; any technology or device that helps people come together can facilitate telepresence, from the humble audio conference and email, through enhanced technologies like video conferencing and audio data conferencing, up to 3D virtual worlds at the research end of the scale.
Teleworking—Practice of working at some distance from employer, either at home or at a 'telecottage', generally relying on electronic means to deliver work or to provide some service.
Temperature Coefficient—In power supplies, change in output voltage per degree centigrade, change of ambient temperature when ac line voltage, output voltage setting, and load resistance are constant.
Temperature Compensation—Correction for influence of temperature on a measurement to a standard temperature reference.
Temperature Error—Maximum change in output, at any input signal within some specified range, resulting from a change in ambient temperature.
TelnetTM—In communications, software service packaged with many operating systems that allows user to get onto system over network in same manner as if a terminal was attached to the system.
Terahertz (THz)—Unit of measurement me equaling one trillion cycles per second
Terminal—In communications, point in network at which data can either enter or leave; also: in communications, a device, usually equipped with a keyboard and often with a display, capable of sending and receiving data over communications link; also: in hard wiring, point where conductors meet to exchange electrical energy.
Terminal Server—Device that allows one or more terminals or other devices to connect to a common bus.
Terminated Line—In digital communication, circuit with resistance at the far end, equal to characteristic impedance of that line so no reflections or standing waves are present when signal is entered at the near end.
Termination—Placement of a connector on a cable.
Termination Pad—Typically flat conducting part of a device to which power or communication signal connector is fastened.
Terminator—Electronic hardware (impedance-matching module) used at the end of some digital signal lines to provide balanced resistance to prevent those reflections or standing waves which can cause errors in data; also: character played by Arnold Schwarzenegger in popular cinema story. J
Test Data Management (TDM)—For global company systems connects isolated test stations into the enterprise to provide information from test data to improve product designs, lower costs, and improve time to market.
Test Point—Process connector to which no instrument is permanently connected, but which is intended for temporary or intermittent connection of an instrument.
TetraFLOPS—Trillion (1012) FLoating Point Operations Per Second.
Text—Sequence of characters forming part of transmission which is sent from data source to data sink, and contains the information to be conveyed; it may be preceded by a header and followed by an "end of text" signal; in ASCII as well as in general communications usage, a sequence of characters treated as an entity if preceded by a "start of text" and followed by an "end of text" control character.
Text Box—Workstation screen view box where user can type information or command requested by application; usually appears within dialog box.
Text Data Mining—Using advanced computing technologies to extract unexpected relationships from huge collections of free-form text documents; see Data Mining.
TFLOPS—Tetra FLoating Point Operations Per Second.
TFT—Thin Film Technology; allows low power operator interfaces, resistant to shock, vibration, immunity to electrical fields and X-rays, diminutive in size, with ease of portability, and bright, high color intensity VGA resolution; as good but expensive alternative to CRTs; also: Thin Film Transistor type active color liquid crystal display, alternative to STN technology.
TGA—TarGA; format from TruVision, Inc. for saving graphics in electronic memory, used for exchanging data between computers.
TGIF—Thank Goodness It's Friday (or Finished). J
THD—Total Harmonic Distortion.
Theory—System of ideas meant to explain something, chosen with view to originality, controversialism, incomprehensibility, and how good it will look in print. J
Thread—In computing programs, One transaction or message in a multithreaded system. See Multithreading.
Thermal Conductivity—Property of a material to conduct heat in form of thermal energy.
Thermal Drift Chart—Illustrates device operating variance due to changes in temperature.
Thermal Expansion—Increase in size due to an increase in temperature expressed in units of an increase dimension per degree.
Thermal Gradient—Distribution of a differential temperature through a body or across a surface.
Thermal Noise—(Usually electrical) noise resulting from thermally induced random fluctuation in current in the receiver's load resistance.
Thermal Printer—Printer design which uses transfer sheet that carries ink in contact with the paper or transparency, and a heated printhead driven by digital data that touches that transfer sheet to attach images to appropriate portions of page.
Thermal Sensitivity Shift—Sensitivity shift within equipment due to changes of ambient temperature from room temperature to specified limits of the compensated temperature range.
THERMISTOR—THERMal resISTOR; resistive circuit component having high negative temperature coefficient of resistance, so that its resistance decreases as temperature increases.
Thermocouple—Device consisting of two dissimilar metals joined together at both ends; voltage developed between these two junctions is proportional to temperature difference between those junctions; used to measure temperature at one end while other is held fixed as the reference (cold) junction.
Type J Iron/Constantan
R Platinum/Platinum 13% Rhodium
S Platinum/Platinum 10% Rhodium
B Platinum 6% Rhodium/Platinum30% Rhodium
G* Tungsten/Tungsten 26% Rhenium
C* Tungsten 5% Rhenium/Tungsten 26% Rhenium
D* Tungsten 3% Rhenium/Tungsten 150 Rhenium
*Not ANSI symbols.
Thermopile—Arrangement of thermocouples in series such that alternate junctions are at the measuring temperature and the reference temperature, to amplify the thermoelectric voltages; often used in radiation pyrometry.
Thermowell—Closed end tube designed to protect temperature sensors from harsh environments of the process.
THF—Time Horizon to Failure.
Thick Client—In client/server architecture, client that performs bulk of data processing operations; data itself is stored on server; usually refers to software, it can also apply to network computer that has relatively strong processing abilities; also called Fta Client, Rich Client; see thin client for contrast.
Thick-Film—Technology using silk screened pastes to form conductor, resistor, themistors, and insulator patterns; screened onto substrate (usually ceramic) and cured by firing at elevated temperatures.
Thicknet—Implementation of IEEE 802.3 standard known as standard Ethernet or Ethernet 10Base5; operates over thick coaxial cable at 10 Megabits per second baseband.
Thin Client—In client/server applications, client designed especially small so that bulk of data processing occurs on server; although usually refers to software, it is increasingly used for computers, such as network computers and Net PCs, that are designed to serve as clients for client/server architectures; network computer without hard disk drive, whereas fat (thick, rich) client includes disk drive; see fat (thick, rich) client for contrast.
Thin Film—Technology using vacuum deposition of conductors and dielectric materials onto a substrate (frequently silicon) to form an electrical circuit.
Thin Space—In typographical composition of screen displays and printing, usually equal to 1/5 of an em, the thin space corresponds to a period or comma in column alignment.
Thinnet—Implementation of IEEE 802.3 standard known as Ethernet 10Base2; operates over thin coaxial cable at 10 Megabits per second baseband.
Third-Party Certification (TPC)—Method of conformity where independent third-party verifies that product meets requirement of appropriate standard and allows their mark to be placed on that product to indicate verification; compare with Supplier’s Declaration of Conformity.
Thomson Effect—When current flows through a conductor within a thermal gradient, a reversible absorption or evolution of heat will occur in that conductor at the gradient boundaries.
Thread—Order of software action of specific task within device, independent of priority in multitasking environment, which continues in that order through multiple interruptions by higher priority functions.
Three Mode Control—Modulating process control action using proportional, integral, and derivative actions.
Three Phase Motor—Relatively inexpensive, self starting motor, with no starting winding or capacitor, to start heavy loads; requires three phase ac power supply.
Three Dimension (3D) printing—Another term for Additive Manufacturing, a process of making a three-dimensional solid object of virtually any shape from a digital model; see Additive Manufacturing
Three Tier Architecture—Software architecture in which the application logic is divided into three parts, or tiers; client tier handles presentation of information to the user, the application services tier handles all of the application logic, and the database tier handles the storage and retrieval of the data from the physical storage; this division of logic allows for application to be distributed across multiple servers that in turn can be optimized for performance.
Three-wire Transmitters―See Type 3 analog (4-20mA) transmitters.
Throughput—Material or product passing through an industrial process; also: rate at which work passes through a manufacturing operation; also: rate at which information is processed through a computer.
Throughput Loss—Ratio of power output divided by power input.
THT—Through Hole Technology; method of mounting elements on a printed circuit boards; see SMT.
THz—TeraHertz; unit of measurement me equaling one trillion cycles per second
TI—Test Instrumentation; also: Test Interface; also: Thermal Imagery; also: Thermal Inertia; also: Time Interval; also: TItanium; also: Total Income.
TIA—(Telecommunications Industries Association) formed in April 1988 after merger of USTSA and Information and Telecommunications Technologies Group of EIA to represent providers of communications and information technology products and services; also: Test Interface Assembly; also: Time Interval Analyzer; also: Tecnicos En Investigacion Aeroterraquea (Spanish comic book); also: Talking in Acronyms J.
TIA/EIA-574—9-position non-synchronous interface between data terminal equipment (DTE) and data circuit-terminating equipment (DCE) employing serial binary data interchange (ANSI/TIA/EIA-574-90) (R98); document provides flexibility of new interface which specifies TIA/EIA-562 Electrical Characteristics which, although they are interworkable with TIA-232-D Electrical Characteristics, are capable of higher data signaling rates and being driven from a +/-5 volt supply; applicable to interconnection of DTE and DCE employing serial binary data interchange where a minimal number of control and information circuits are required; provides solution to problem of incorrect referencing. (This Standard was developed in recognition of the fact that a defacto interface had appeared in industry which, although it used Circuit Definitions and Electrical Characteristics of TIA-232-D, was implemented on 9-pin connector instead of the 25-pin connector specified in the Standard, but because no Standard existed for this interface, many manufacturers incorrectly labeled this defacto interface "RS-232" causing confusion to the user community; TIA-574 resolves this dilemma.
TIE—Technical Information Exchange.
TIFF—Tagged Image File Format; for saving bit mapped graphics in electronic memory, used for exchanging data between computers.
TIGA—Texas Instrument Graphics Architecture.
Time Base Corrector—Electronic device that corrects inconsistencies in the rhythm of a video signal; often used to make video recorder playback stable.
Time Base Error—Flutter in horizontal sweep rate of video signal, in videotape recorders this can be caused by tape stretch or inherent imperfections in transport mechanism.
Time base—Cadence of video signals that control scanning of image, maintaining its stability.
Time Boxing—In planning techniques, to limit long term vision or project into more practical lengths, often identified by "milestones."
Time Division Multiplexor (TDM)—Device that accepts multiple channels on a single transmission line by connecting terminals, one at a time, at regular intervals, interleaving bits (Bit TDM) or characters (Character TDM) from each terminal.
Time Domain Reflectometry—Method of finding cable faults by sending out high frequency pulses, when signal reaches problem point, it bounces back to tester; technology also used in one level sensor design to locate surface of material.
Time Processing Unit (TPU)—Sophisticated timer that in addition to counting down, can detect input events, generate output events, and other useful operations.
Time Proportional—Process control response that is either full ON or full OFF, but ON duration and OFF duration is proportional to deviation from set point.
Time Sharing—Method of computer operation that allows several interactive terminals to use one computer; although terminals are actually served in sequence, the high speed of computer makes it appear as if all terminals were being served simultaneously.
Time Slot—Some assigned period of time, or an assigned position in some sequence, for operation usually of microprocessor.
Time-Out—Expiration of predefined time period at which point some specified action occurs; in communications, time-outs are employed to avoid unnecessary delays and improve traffic flow.
Time-Slice Multitasking—Truest form of multitasking, found on sophisticated workstations, where each task has microprocessor attention for fraction of second, then tasks are performed in sequential order by priority; compare Context Switching Multitasking and Cooperative Multitasking.
Tints—In video screen displays and printing, various even tone areas (strengths) of solid color.
Tip and Ring—Traditional telephone terminology (U.S.) for “positive” and “negative” polarities based on old style telephone switchboards; “tip’ wire, connected to tip of plug, “ring” wire connected to slip ring in the jack.
TI´T—Therrre It ´Tis; phrase an old Irish high school math teacher of mine used in analytical geometry class instead of QED, see QED. J
TITO—Twin Input Twin Output; systems requiring more sophisticated control methods than single loop controllers; see SISO, MIMO, MISO.
TLA—Three Letter Acronyms; often used to make everyone else feel ignorant since you obviously know what the heck you’re talking about, and anybody else who can’t is obviously thick; used liberally when you want people to recognize your genius. J
TLS—Transparent LAN service, see Virtual Private LAN Service.
TMS—Transportation Management System.
TMR—Triple Modular Redundant; three devices in voting mode of 2 out of 3 to assure system availability.
TOC—Total Organic Carbon; measurement which with proper interpretation can be indicator of pollution level in wastewater stream.
TOE—Time Of Event.
Toggle—Pertaining to any device having two stable states, such as forward/back, ON/OFF, etc.
Token Bus—In digital communication, LAN standard that uses token passing media access method (ISO data link layer 2) where right to transmit is passed from device to device by way of a logical ring on a physical bus configuration.
Token Passing—In digital communication, media access method (ISO data link layer 2) for peer-to-peer communication bus nodes; token is passed around to each node on a regular schedule, making throughput and response time predictable (deterministic); only one node has token at any one time, and during that time it has complete control of the network.
Token Ring—In digital communication, LAN standard that uses token passing media access method (ISO data link layer 2) in which special data packet (called token) is passed from one station to another along (physical) electrical ring; when station wants to transmit, it takes possession of token, transmits its data, then frees token after data has made complete circuit of electrical ring; second most popular LAN technology, originally IBM's answer to Ethernet, now the IEEE 802.5 standard; runs at either four or 16 Mbits/sec.
Tolerance—Maximum allowable deviation of electrical, environmental, or dimensional parameters of a device, equipment, or system, usually given in percent.
Tools—In context of data processing, software programs to aid in the planning, design, implementation, maintenance, and diagnosis of computer systems.
TOP—Technical and Office Protocols; Boeing® version of MAP protocol aimed at office and engineering applications to enable MAP devices on IEEE 802.4 to interface with office systems on IEEE 802.3; closely associated with GOSIP being developed by NIST.
TOPFET—Temperature and Overload Protected Field Effect Transistor; power protected MOSFET.
Topology—Logical and/or physical arrangement of stations on a network, such as star, ring, multidrop, tree.
Total Cost of Ownership—More than selling price, includes cost of total services and parts to keep system operational over its lifetime.
Total Productive Maintenance (TPM)
— Equipment and process improvement strategy that combines Preventative
Maintenance and Predictive Maintenance concepts with personnel assets for team
approach to continuous plant improvement, and elimination of bureaucratic and
organizational lines between production and maintenance departments intended to
promote total quality control and employee involvement; strategy links many
elements of good maintenance program to achieve higher levels of equipment
effectiveness; key elements include:
1. Improving equipment effectiveness by targeting the major losses
2. Involving operators in the daily, routine maintenance of their equipment
3. Improving maintenance efficiency and effectiveness
4. Training for everyone involved
5. Life-cycle equipment management and maintenance prevention design
6. Winning with teamwork focused on common goals
Total Quality—Holistic approach to quality control which stresses building of manufacturing process that forces their users to confront quality problems rather than passing them on.
Total Quality Management—Unlike top-down SQC, every individual in process is viewed as manager of quality improvement as part of a manager/laborer team.
Touchscreen—Video screen (CRT) with which operator can interact by touching icons on screen display, rather than through keyboard or mouse.
TOX—Total Organic halide; measurement which with proper interpretation can be an indicator of pollution level in a wastewater stream.
TP—Twisted Pair; wiring for signals; also: True Position.
TPC—Third-Party Certification; see definition.
TPG—Test Pattern Generator.
TKIP—Temporal Key Integrity Protocol; see WPA.
TPM—Total Productive Maintenance, see definition.
TPU—Time Processing Unit, see definition; also: Tank Pump Unit (Tank & Pump Unit).
TQC—Total Quality Control.
TQM—Total Quality Management, see definition.
Traceability—Documentation of existence of a calibration chain between an instrument and a primary standard.
Track—Ring shaped portion of magnetic disk surface area for digital memory, defined by minimum and maximum distance from disk center.
Trackball—Input device for video screen (CRT) with a ball recessed in its surface, with which user rotates to control position of cursor; also: unusual game dangerously played along railways. J
Traffic Director—In digital communication, network "master" station which performs "polling" as media access method of controlling devices on bus (multipoint, multidrop) or ring (loop) type network; using process of inviting another station or node to transmit data, compared to selecting.
Transaction—In communications, a message destined for an application program; a computer processed task that accomplishes a particular action or result; in interactive communications, an exchange between two devices, one of which is usually a computer; in batch or remote job entry, a job or job step.
Transaction Processing—Type of computer processing in which the computer responds immediately to user requests where each request is considered to be a transaction (automatic teller machines for banks are an example of transaction processing); opposite of transaction processing is batch processing, in which a batch of requests is stored and then executed all at one time; transaction processing requires interaction with a user, whereas batch processing can take place without a user being present.
Transceiver—Device that can both transmit and receive data communications; also known as Media Attachment Unit (MAU) and not to be confused with a Token Ring MAU (Media Access Unit), Ethernet device for transmitting and receiving data that often provides data packet collision detection as well; can either be internal or external feature of network device such as network interface card, repeater, hub, or concentrator; multiport MAU, or transceiver, allows number of computers or workstations to be attached to single connection on Ethernet bus and each port performs standard transceiver functions.
Transducer—Device for converting energy from one from to another, such as pneumatic to electric, mechanical to pneumatic, optical to electrical, etc.; general term for device that receives information in form of one or more physical quantities, modifies that information and/or its form, if required, and produces resultant output signal; depending on application, transducer can be primary element, transmitter, relay, converter, or other device...because term is not specific, its use for specific applications is not recommended.
Transducer Block (TB)—In FOUNDATION Fieldbus technology, decouples Function Blocks (FBs) from local Input/Output (I/O) functions required to read sensors and command output hardware; Transducer Blocks (TBs) contain information such as calibration date and sensor type; there is usually one TB channel for each input or output of a Function Block (FB).
Transducer Electronic Data Sheet (TEDS)—Digitally accessible specifications within (smart) transducer itself, communicated over digital connection to other devices (such as on IEEE-P1351 defined fieldbus) to ensure appropriate device has been installed and is compatible, or even on some devices, adjusts their compatibility; through combination with NCAP and STIM, newly installed transducer can effectively announce and define itself to others on same network; see STIM, NCAP.
Transient—Abrupt changes in voltage, of short duration, such as brief pulse induced by operation of a switch; sometimes called “spike.”
Transient Response—Time required for output voltage to return within the dc regulation envelope for a step change of input voltage or dc output current; normally specified in microseconds for 50 percent load change from one-half to full load.
Transient Overvoltage—Peak voltage in excess of steady state voltage for short time during transient conditions (e.g., resulting from operations of a switching device).
Transitional Flow—Flow between laminar and turbulent flow, usually between a pipe Reynolds number of 2000 and 4000.
Transmission—Sending of signal, message, or other form of information over some medium; series of characters, messages, or blocks, including control information and other user data.
Transmission mode—Technique by which device recognizes beginning and end of character clocking in synchronous transmission; start and stop bits in asynchronous.
Transmitter—Device which translates low level output of sensor or transducer to higher level signal suitable for transmitting to site where can be further processed; sensor may or may not be integral with transmitter; see Type 2, Type 3, Type 4; also: in FOUNDATION Fieldbus technology, active fieldbus device containing circuitry which applies a digital signal on the bus.
Transoptimal Engineering—A system designed with so many advanced features, it is too confusing to be useful (usually a favorite, comfortable product that comes out with a new version, like computer folks do) J
Transparent GIFFs—In digital graphics, subset of original GIF file format that adds header information to GIF file, which signifies that color will be masked out.
Transparent Mode—Transmission of binary data with recognition of most control characters suppressed; in binary synchronous communications, entry to and exit from transparent mode is indicated by sequence beginning with special Data Link Escape (DLE) character.
Transport Layer—In digital communication, layer four in OSI reference model; provides a logical connection between processes on two machines.
Transportability—Neither chained to a wall nor attached to an alarm system. J
Tree—LAN topology that recognizes only one route between two nodes on the network; the "map" resembles a tree or the letter T.
TrDC—TRuly Distributed Control; a concept that places single loop control out into the process at the point of the sensors and final elements similar to what was done in the 1930s & 1940s, except that they are digitally connected to a central display.
TRI—Toxic Release Inventory; required by companies in the U.S. by the EPA to control industrial environmental releases.
Triac—Solid state switching device used to switch alternating current wave forms.
Triboluminescence—Light emitted when particles bump into one another.
Trim—In video development, purpose of adjusting length of video clip or other element; this feature allows editors to quickly, precisely, and only slightly change IN or OUT points of clip; also: in process modulating valves, the port & plug components, which are the controlling surfaces.
Triple Point—Temperature and pressure at which solid, liquid, and gas phases of a given substance are present simultaneously in varying amounts.
Trouble Light—Home mechanic's own tanning booth; sometimes called a drop light, it is a good source of vitamin D, "the sunshine vitamin," which is not otherwise found under cars at night; health benefits aside, its main purpose is to consume 40-watt light bulbs at about the same rate that 105 mm howitzer shells might be used during, say, the first few hours of the Battle of the Bulge; more often dark than light, its name is somewhat misleading. J
TRMS—True Root Mean Square.
Trojan Horses— Apparently innocuous but unauthorized software programs hidden within authorized programs which, when loaded into a system or network, will otherwise function similar to viruses, will allow access to a virus, or can be designed to give system access to a specific “cracker;” see Cracking; “Computer Viruses, Worms, & Trojan Horses”.
Trunk—Single circuit, usually of multiple channels, between two points, both of which are switching centers or individual distribution points; usually handles many channels simultaneously; also: in FOUNDATION Fieldbus technology, main communication highway between devices on an H1 fieldbus network; acts as a source of main supply to Spurs on the network.
Trust Relationship—In Windows NT, association between servers in one domain or an association between one domain and another; allows user to log on once and have access to all associated resources without having to be authenticated again; In later versions, process of defining trust relationships is automated.
Trustworthy Computing Initiative Security Resources—Comprehensive collection of materials to help Microsoft customers understand and enhance the security of their Microsoft software-based computers. (http://www.microsoft.com/mscorp/twc/security/resources.mspx)
TSB—Tension Set Bolt; a term no longer used; see Tension Control Bolt which is the modern name; also: Terribly Strong Bolt. J
TSCA—Toxic Substances Control Act; U.S. federal law passed in 1976 authorizing EPA to collect information on chemical risks; the basis for regulating such toxic substances as PCBs.
TSE—(Turkish Standards Institution).
TSR—Terminate & Stay Resident (MS-DOS®).
TSS—Total Suspended Solids; a consideration in EPA (U.S.) regulations.
TTA—Technology Trend Assessment.
TTL, T2L—Transistor-Transistor Logic; form of solid state logic which uses only transistors to form logic gates.
TTP—Trusted Third Party; in business conducted over the Internet, type of intermediary responsible for ensuring the identification and authentication of the business partner; often it uses security technologies.
Tunneling—In digital communications, transmitting data structured in one protocol format within format of another protocol; allows other types of transmission streams to be carried within prevailing protocol; see Tunneling Protocol.
Tunneling Protocol—A network protocol that encapsulates packets at a peer level or below; used to transport multiple protocols over a common network as well as provide the vehicle for encrypted virtual private networks (VPNs); said to "tunnel" because it "pushes through" packets of different types; sometimes called an "encapsulation protocol," which is ambiguous naming, because many network protocols encapsulate.
Tuning Adjustments—No two systems require same tuning adjustments for optimum control, nor does any one system require same tuning adjustments under all possible operating conditions; so controllers (and control algorithms) have adjustable settings to insure optimum operation.
Turbidity—Measurement to quantify deviation between clear water and water containing suspended solids, usually through measurement of loss of light due to absorbence and scattering.
Turbochannel—100 MB/sec bus in DECstation 5000/200 by Digital Equipment Corporation with no license charge or royalty.
Turbulent Flow—When forces due to inertia are more significant than forces of velocity; typically occurs with Reynolds number in excess of 4000.
Turn On Time—Rise Time which is sometimes measured between the 20% and 80% points; see Rise Time.
Turnaround Time—Elapsed time between submission of job to computer and return of results; also: in communications, actual time required to reverse direction of transmission from sender to receiver or vice versa when using half duplex method (time is required by line propagation effects, modem timing, and computer reaction).
Turndown—Ratio of maximum plant design flow rate to minimum plant design flow rate; see Rangeability, inherent.
Turnkey System—Equipment or computer system that is delivered complete, installed, and ready to operate.
Turnoff Time—Fall Time which is sometimes measured between the 80% and 20% points; see Fall Time.
TÜV—(Technischer Überwachungs Verein); German national electrical safety body.
TVO—Total Value of Ownership.
TVS—Transient Voltage Suppresser.
Tweezers—Tool for removing wood splinters and wire wheel wires. J
Twinax—Twinaxial Cable; uses twisted pair of conductors within shielding to improve resistance to RFI/EMI over coaxial cable; see Coax.
Twisted Pair—Two insulated copper conductors that are wound around each other to cancel effects of electrical fields (noise in signal).
Two Mode Control—Modulating process control action using proportional and integral actions.
Two Tier Architecture - Software architecture in which application logic is divided into two parts, or tiers; the application logic is typically included either with the client or the database as one tier and the remaining logic is in the server as the other tier; compare: Three Tier Architecture.
Two-Ton Hoist—Tool for testing maximum tensile strength of everything you forgot to disconnect. J
Two-wire Transmitters―See Type 2 analog (4-20mA) transmitters.
TWT—Traveling Wave Tube.
TxD—Transmit Data; digital data signal output, usually from computer transmitter to receiver.
Type 2 Transmitters―4-20mA transmitters that require two wires to simultaneously carry excitation power and output signal; other names include two-wire, single-ended, non-isolated, and input isolated transmitters.
Type 3 Transmitters―4-20mA transmitters that require three wires to simultaneously carry excitation power and output signal; other names include three-wire, single-ended, non-isolated, and input isolated transmitters.
Type 4 Transmitters―4-20mA transmitters that require four wires; two for excitation power, and two wires for output signal; other names include four-wire, self powered, power isolated, and power isolated transmitters.
Typical Measurement—Error of value is within plus or minus one standard division (±1%) of nominal specified value, as computed from total population of values.
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