Explore chapters and articles related to this topic
Computer-Aided Manufacturing
Published in Sherif D. El Wakil, Processes and Design for Manufacturing, 2019
The punched tape used for NC systems is standardized by the EIA to have a width of 1.000 ± 0.003 inches (25.4 ± 0.076 mm) and a thickness of 0.004 ± 0.0003 inches (0.1 ± 0.008 mm). The tape can be made of paper, a paper Mylar sandwich, or an aluminum-Mylar laminate. Paper tapes are cheap and easy to damage, so their use is limited to short runs. For high production and frequent use, aluminum-Mylar tapes are more suitable because of their durability, but they are more expensive. NC tapes are purchased in the form of rolls that are 8 inches (200 mm) in diameter, each having a tape length of up to 2000 feet (600 m). The tape is divided into eight main channels, or tracks (i.e., parallel to the edges), where holes can be punched. There is also a track of smaller holes to the right of the third main track. These smaller holes fit the tape-feeding sprocket in order to ensure positive drive of the tape. Letters of the English alphabet, digits from 0 to 9, and symbolic signals to the MCU each have a specific arrangement of punched holes in a line, or row, perpendicular to the edges of the NC tape. A single instruction given to the MCU usually consists of a set of letters and numbers; a set of rows of punched holes is referred to as a word. There are, however, some words that take only a single row. A number of words that are grouped together form a data block. The block is the smallest unit of a program that provides the NC system with complete information for an operation (or tool motion).
P
Published in Philip A. Laplante, Comprehensive Dictionary of Electrical Engineering, 2018
paper tape paper tape strips of paper capable of storing or recording information, most often in the form of punched holes representing the values. Now obsolete. Papoulis' generalization a sampling theory applicable to many cases wherein signal samples are obtained either nonuniformly and/or indirectly. parabolic index profile quadratic transverse variation of the index of refraction; leads to analytic solutions of the paraxial equations for rays and beams. parabolic reflector a reflecting surface defined by a paraboloid of revolution or section of a paraboloid of revolution. paraelectric the nonpolar phase into which the ferroelectric transforms above Tc , frequently called the paraelectric phase. parallel adder a logic circuit that adds two binary numbers by adding pairs of digits starting with the least significant digits. Any carry generated is added with the next pair of digits. The term "parallel" is misleading, since all the digits of each numbers are not added simultaneously. parallel architecture a computer system architecture made up of multiple CPUs. When the number of parallel processors is small, the system is known as a multiprocessing system; when the number of CPUs is large, the system is known as a massively parallel system. parallel bus a data communication path between parts of the system that has one line for each bit of data being transmitted. parallel computing computing performed on computers that have more then one CPU operating simultaneously. parallel computing system a system whose parts are simultaneously running on different processors. parallel data transfer the data transfer proceeds simultaneously over a number of paths, or a bus with a width of multiple bits, so that multiple bits are transferred every cycle. A technique to increase the bandwidth over that of serial data transfer. parallel feed parallel I/O See corporate feed. See parallel input/output.
Neutronics Calculation Advances at Los Alamos: Manhattan Project to Monte Carlo
Published in Nuclear Technology, 2021
Avneet Sood, R. Arthur Forster, B. J. Archer, R. C. Little
By 1972, the MCN code accessed pointwise data in Lawrence Livermore Laboratory (LLL) or the Atomic Weapons Research Establishment (AWRE) format. Interestingly, the data were read from a library maintained on the disk of the MANIAC. Documentation of the United Kingdom’s AWRE nuclear data library at this time may be found in Ref. 89. The LLL data have been described over the years in a comprehensive series of Lawrence Livermore reports produced under the leadership of Robert Howerton (see UCRL-50400, for example, Ref. 90). From revision 1 of that document (1981), a bit of the history was presented: The LLNL Evaluated Nuclear Data Library has existed since 1958, in a succession of forms and formats. In its earliest form it was a series of internal memos containing tabulations of cross sections and angular distributions for a few isotopes to be used in neutronics calculations. It was soon found that some type of mechanization should be undertaken both for efficiency and for convenience. Thus, in rapid succession, the library went through stages of punched card and punched paper-tape, and then to the first magnetic-tape BCD card image form. Of course, once the library was in one computer-readable form, it could be translated with relative ease to another computer-readable form.