Computer formulations of aircraft models for simulation studies

Recent developments in formula manipulation compilers and the design of several symbol manipulation languages, enable computers to be used for symbolic mathematical computation. A computer system and language that can be used to perform symbolic manipulations in an interactive mode are used to formulate a mathematical model of an aeronautical system. The example demonstrates that once the procedure is established, the formulation and modification of models for simulation studies can be reduced to a series of routine computer operations

Implementation of a macro-processor for string handling

In this work TRAC is implemented in FOTRAN IV. This will enable various users to compile this FORTRAN version and use it in their own installations making only minor modifications to meet individual specifications. The way of the implementation allows adding either existing TRAC functions which are not included in this work or completely new, primitive functions needed for specific, well-defined purposes. TRAC is a very flexible interactive language with versatile capabilities at execution time. The presented processor is programmed in FORTRAN IV using IBM 360 44PS and RAX facilities. It is compiled and intended to be used as a software package providing TRAC language facilities for the 360 RAX REMOTE ENTRY COMPUTING SYSTEM. It can be used under 44PS for special purposes. TRAC is a member of the set 'STRING MANIPULATTON LANGUAGES'. A thorough examination of this set helps to understand the basics of operations and techniques for dealing with strings. Another member of the same set is described briefly: this is the 'SNOBOL LANGUAGE' 'String manipulation languages' is a subset of the set 'SYMBOL MANIPULATION LANGUAGES'. Some of the fundamental ideas and principles for symbol manipulation are included. The most-known languages, techniques and applications are mentioned, followed by references to allow further research and investigation. The above are introduced in the following order: 1. Symbol Manipulation Languages, 2. String Manipulation Languages. 3. TRAC Language

The Markov algorithm as a language parser—Linear bounds

The Markov algorithm [1, 2] can be used as a language parser and as means fordefining languages [2–5]. This work is concerned with the amount of computing time which the algorithm requires. Computing time is measured by the number of comparisons between the rules of the grammar and the input string. A modification is introduced into the algorithm which reduces the computation time. It is proved that under certain conditions imposed on the rules of the grammar the computing time required by the modified algorithm is bounded linearly by the length of the input string. One set of such conditions requires that each application of a grammar rule reduces the length of the input string. Another set requires that each application does not increase the length of the input string and that the graph associated with the rules of the grammar satisfies certain restrictions

Interactive specification of data displays

On-line graphical language for computer data displa

Garbage Collection in a Very Large Address Space

This research was done at the Artificial Intelligence Laboratory of the Massachusetts Institute of Technology and was supported by the Office of Naval Research under contract number N00014-75-C-0522.The address space is broken into areas that can be garbage collected separately. An area is analogous to a file on current systems. Each process has a local computation area for its stack and temporary storage that is roughly analogous to a job core image. A mechanism is introduced for maintaining lists of inter-area links, the key to separate garbage collection. This mechanism is designed to be placed in hardware and does not create much overhead. It could be used in a practical computer system that uses the same address space for all users for the life of the system. It is necessary for the hardware to implement a reference count scheme that is adequate for handling stack frames. The hardware also facilitates implementation of protection by capabilities without the use of unique codes. This is due to elimination of dangling references. Areas can be deleted without creating dangling references.MIT Artificial Intelligence Laboratory Department of Defense Office of Naval Researc

Design of the software development and verification system (SWDVS) for shuttle NASA study task 35

An overview of the Software Development and Verification System (SWDVS) for the space shuttle is presented. The design considerations, goals, assumptions, and major features of the design are examined. A scenario that shows three persons involved in flight software development using the SWDVS in response to a program change request is developed. The SWDVS is described from the standpoint of different groups of people with different responsibilities in the shuttle program to show the functional requirements that influenced the SWDVS design. The software elements of the SWDVS that satisfy the requirements of the different groups are identified

FRIC: an expert system to recognize fricatives

In building a speaker independent continuous speech understanding sys tem, a method is needed to translate the speech signal to a phoneme string. Current recognition attempts based on statistical methods are not as accurate as desired and require vast numbers of templates for comparison. On the other hand, human experts can transcribe phoneme strings from spectrograms with a high degree of accuracy, without needing to match unidentified seg ments against identified templates. This paper discusses the development of Fric, an expert system for identifying fricative phonemes, intended to func tion as part of a phoneme identification knowledge source. Fric attempts to mimic the techniques used by human transcribers in identifying phonemes. RuleMaster, an expert system building tool developed by Radian Corporation, was used to create this system. Fric uses both forward and backward chaining as control strategies and includes an explanation system for both debugging and explanatory purposes

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