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jabber 1. Continuous transmission on a medium because of a faulty device. [ANSI/ISA-50.02, Part 21992] 2. The error condition that occurs when a network .. device transmits packets that are larger than the maximum allowable size or will not relinquish token (depending on the media access method being used). jack A connecting device to which the wire or wires of a circuit may be attached and that is so arranged that a plug can be inserted into it. jacket 1. A plastic layer that is applied over the coating of an optical fiber or sometimes over the bare fiber. Jackets are used for color coding in optical cables, tit make handling easier, or to protect the fiber against mechanical stress and strain, 2. A stiff plastic protective material that encases a floppy disk with slots so a disk drive can access the data. 3. The layer of plastic, fiber, or metal that surrounds insulated electrical wires, thereby forming a cable. This outer cover may be for the mechanical or environmental protection of the wires wi thin. jacketed valve A valve body that is cast with a double wall or provided with a double wall by welding material around the body. This ~forms a passage for a heating or cooling medium. Jacketed valve also refers to valves that are enclosed in split-metal jackets that have internal heat passageways or electric heaters. These valves are also referred to as "steam jacketed" or "vacuum jacketed." In a vacuum-jacketed valve, a vacuum is created in the space between the body and secondary outer wall in order to reduce the transfer of heat by convection from the atmosphere to the internal process fluid, which is usually cryogenic. [ANSI/ISA-75.05.01-2000] jackscrew 1. A portable device for lifting a heavy load a short distance by means of a screw mechanism. 2. The screw of such a device. jackshaft A countershaft, and especially an auxiliary shaft that is used between two other shafts. jamming The intentional transmission of radio frequency waves for the purpose of interfering with transmissions from another station. Japanese MAP Users Group See Manufacturing Automation Protocol (MAP). Java A software code that can run on multiple platforms (UNIX, OS/2, NT, Macintosh,
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etc.). It was originally developed by Sun Microsystems Inc. as a platform for programming on smallembedded devices, such as cell phones, PDAs, and sensors. Sun claims that it is simpler than C++, and it also has significant implications for use on Internet applications. Java Beans Reusable chunks of Java software code that can be assembled as components in larger applications. jaw The part or.parts of a current clamp that surround(s) the cOl1ductor being tested in order to pick up the magnetic field. [ANSI/ISA-82.02.04-1996 (IEC 61010-2-032)] jaw opening The part or parts of the jaw that open(s) while clamping around a conductor. [ANSI/ISA-82.~2:04",1.996(IEC 61010-2-032)] jerk 1. The time r'ah~ of change of acceleration. Expressed in feet/s 3, cm/s3, gn/s. . (ISA-37.1-1979 (R1982)] 2. A sudden, abrupt motion. jet A rapid flow 'of fluid from a nozzle or orifice. jetness The darkness of a pigment. It is typically caused by the size of carbon black agglomerates (smaller black agglomerates cause darker films). jet pump A type of pump that uses a jet of fluid to induce flow in another fluid. jewels Recessed bearings of glass, sapphire, or diamond that support the ends of a pivot pin in an instrument or in a fine mechanical watch or clock. JIT just-in-time manufacturing. A delivery approach that stresses the benefits of the "pull" system, wherein material is brought to the work site only when it is needed. JIT requires that all related activities be closely synchronized. jitter A slight movement of a signal in time or phase that can introduce errors and cause loss of synchronization in high-speed synchronous communication. job A group of computer data and control statements that do a unit of work. An example is a program and all its related subroutines, data, and control statements. Also called a "batch control file." See batch control. job control language (Jeu A lang'\lage for identifying a job and requesting ~ion from a computer operating system. .~ Johansson curved crystal spectrometer A type of spectrometer that has a reflecting .crystal whose face is concave. As a result, X-rays that diverge slightly after passing through the primary slit are refocused at the detector slit.
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joint / justify
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joint A separable or inseparable juncture between two or more materials. joule A metric unit for energy, quantity of heat, or work. journal That part of the s11aft that rides in a plain cylindrical bearing. joy stick A device by which an individual can position the cursor on a cathode ray tube. An alternative to the mouse. JPEG Joint Photographic Experts Group. A working con1mittee under the auspices of tl1e ISO that is attempting to define a universal standard for digital compressing and decompressing still images for use in al1d exchanged between computer systems. The JPEG algorithm reduces the image size by as much as 65:1 and maintains image integrity by eliminating imperceptible color information. \ JTM Job Transfer and Manipulation. Jules' Own Version of the International Algorithmic Language <JOVIAL) A compiler language based on the International Algorithmic Langllage, ALGOL. jump An instruction that causes a nevv address to be entered into a computer program counter. The program continues to execute from the ne\v program counter address. jumper A temporary wire that is used to bypass a portion of an electrical circuit or to attach an instrument or other device during testing or troubleshooting. jumper tube A short tube connection for by-passing, routing, or directing the floyv of fluid as desired. junction 1. The point where any two or more wires are joined. 2. The point in a thermocouple \vhere two dissimilar metals are joined. 3. The portion of a transistor at vvhich opposite types of sen1iconductor material meet. junction box A protective enclosure around the connections betvveen electric wires or cables. jury rig A makeshift or temporary assembly. justification 1. The act of adjusting, arranging, or shifting digits to the left or rig11t in order to fit a prescribed pattern. 2. Spacing out the words in printed material so that each line is the same length. justify To align computer data around a specified reference.
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