Click for next page ( 60


The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 59
GLOSSARY Automated Manufacturing Research Facility (AMRE) A facility at the National Bureau of Standards for examining the problems of control, data base management, and metrology associated with automated machining centers. Computer-Aided Design (CAD) Application of the computer to the creation, modification, or evaluation of product design. Computer-Aided Manufacturing (CAM) Application of the computer to the planning, control, and operation of production of a product. Computer-Integrated Manufacturing (CIM) Computer-integrated manufacturing (CIM) in a manufacturing enterprise occurs when: all the processing functions and related managerial functions are expressed in the form of data, these data are in a form that may be generated, transformed, used, moved, and stored by computer technology, and these data move freely between functions in the system throughout the life of the product, with the objective that the enterprise as a whole have the information needed to operate at maximum effectiveness. 59

OCR for page 59
60 Concurrent Access The ability of a data base management system to service more than one user at a time. There are degrees of concurrency; for example, a system that provides file level concurrency will permit multiple users to be connected simultaneously to the data base as a whole, but will only permit one user at a time to be using any given file within the data base, whereas a system that provides record level concurrency will even permit multiple users to be accessing the same file at any given time, but any given record can only be under the control of a single user at any time. Data Management The technology whereby all the data for a given enterprise are stored in a centralized repository in a computer--as opposed to the data being stored in separate, uncoordinated files. Data management implies centralized control over such aspects as organization, structural definition, privacy, and recoverability, as well as the concept that all users use this central resource instead of maintaining their own copies of the data. Data Definition Language (DDL) With multiple programs and users accessing a common data base, it is important that they all use a single, centralized description of the data base rather than each user describing it separately and redundantly. This centralized and common description is ex- pressed in a Data Definition Language, usually referred to as DDL. Data Manipulation Language (DML) The data in a data base are accessed and manipulated by computer programs using a particular set of commands understood by the data management system. These are collectively referred to as the Data Manipulation Language or DML. Such a language may be usable on its own or may need to be embedded within some other programming language such as COBOL. Data Model A data base management system permits the data within a data base to be structured according to one (or possibly more) data models. Such a model defines how a user program perceives the data in the data base and usually implies certain restrictions on how the data may be accessed, interrelated, and traversed. The three most popular data models are:

OCR for page 59
61 Hierarchical--In this model, data relationships are restricted to a "one-to-many" structure, where any given record type can belong to only one owner (above it) in a hierarchy, but may itself own many record types (below it) in a hierarchy. It is synonymous with a "tree" structure, where a trunk can support many branches, and a branch can support many twigs, but not vice versa. Network--In this model, data relationships may exist that reflect a "many-to-many" structure, where any given record type may be related to many other record types in a general network structure, rather than being restricted to a hierarchical tree. Thus it may be "owned" by many record types, as well as itself "own" many record types. Relational--In this model, the different files in a data base are viewed as tabular two-dimensional matrices of "flat files," with the rows of a matrix as the records in a file and the columns as the data fields within the records. Relationships may be materialized dynamically between any two files that contain a com- mon data field that can be used to relate the individual records in one to the individual records in the other. Also implied in this model is the ability to access and manipulate the data files (or "tables") at that level rather than on a record-at-a-time basis as is usually the case in hierarchical and network models. Flexible Manufacturing System (FMS) An integrated system of automated machines, equipment, and work- and tool-transport apparatus, all operating under computer control. Integrated Computer-Aided Manufacturing Program (ICAM) An Air Force program to improve productivity in aerospace batch manufacturing through widespread application of computer-based, fully integrated factory management and operation systems. Integrated Program for Aerospace Vehicle Design (IPAD) A program funded by NASA and the Navy and aimed at raising aerospace productivity through advancement of technology to integrate and manage information involved in the design and manufacturing process. Integration Having a data structure supporting a free flow of all data resi- dent in the system of manufacturing to any part of the system as

OCR for page 59
62 needed. The data stream can, while remaining consistent, continu- ally grow and be enriched while supporting all required functions throughout the organization and during the life of the product. Interface A shared boundary Manufacturing The Committee uses the term ''manufacturing" in its broadest sense, to include all activities in the conversion of raw materials into end products. These activities range from the perception of a need for a product, through the conception, design, and development of a product, preparation for production, production of the product, marketing of the product, and, ultimately, support of the product in use. Multilevel Schema A multilevel schema permits data descriptions of the contents of a data base to be expressed at multiple levels of abstraction. Thus at one level, the description may show many disjoint types of records that would need to be addressed as separate units by a program using that particular level of schema. At the next higher level of schema, however, the same data may be described as one single conglomerate record that could be addressed and manipulated by a program as a single unit by referencing it through this higher level schema. Numerical Control (NC) Automatic control of processes by the proper interpretation of data prerecorded in symbolic form. Product Definition Data Interface (PDDI) An ICAM project aimed at defining needs for manufacturing data from engineering. Schema A description or definition of a data base in terms of its data elements and their relationships.