Engineering topics

Feyock, S.

Publications and source records attributed to Feyock, S..

7 records

NASA NTRS1986

A high-order language for a system of closely coupled processing elements

The research reported in this paper was occasioned by the requirements on part of the Real-Time Digital Simulator (RTDS) project under way at NASA Lewis Research Center. The RTDS simulation scheme employs a network of CPUs running lock-step cycles in the parallel computations of jet airplane simulations. Their need for a high order language (HOL) that would allow non-experts to write simulation applications and that could be implemented on a possibly varying network can best be fulfilled by using the programming language Ada. We describe how the simulation problems can be modeled in Ada, how to map a single, multi-processing Ada program into code for individual processors, regardless of network reconfiguration, and why some Ada language features are particulary well-suited to network simulations.

Feyock, S.↗

NASA NTRS1986

Implementation of artificial intelligence rules in a data base management system

The intelligent front end prototype was transformed into a RIM-integrated system. A RIM-based expert system was written which demonstrated the developed capability. The use of rules to produce extensibility of the intelligent front end, including the concept of demons and rule manipulation rules were investigated. Innovative approaches such as syntax programming were to be considered.

Feyock, S.↗

NASA NTRS1985

Moving target, distributed, real-time simulation using Ada

Research on a precompiler solution is described for the moving target compiler problem encountered when trying to run parallel simulation algorithms on several microcomputers. The precompiler is under development at NASA-Lewis for simulating jet engines. Since the behavior of any component of a jet engine, e.g., the fan inlet, rear duct, forward sensor, etc., depends on the previous behaviors and not the current behaviors of other components, the behaviors can be modeled on different processors provided the outputs of the processors reach other processors in appropriate time intervals. The simulator works in compute and transfer modes. The Ada procedure sets for the behaviors of different components are divided up and routed by the precompiler, which essentially receives a multitasking program. The subroutines are synchronized after each computation cycle.

Collins, W. R.↗

NASA NTRS1983

ADA and multi-microprocessor real-time simulation

The selection of a high-order programming language for a real-time distributed network simulation is described. The additional problem of implementing a language on a possibly changing network is addressed. The recently designed language ADA (trademarked by DoD) was chosen since it provides the best model of the underlying application to be simulated.

Feyock, S.↗

NASA NTRS1983

The use of Ada in distributed simulations

The increasing need for detailed information about systems of continually growing complexity enhances steadily the demands regarding the employed models. The present investigation is concerned with work related to the development of high-performance computer hardware intended for the support of the real-time simulation of jet engines. The hardware is structured in the form of a network of communicating microprocessors running in parallel. The need for a higher-order language capability for programming such a network has led to the research considered in this study. Attention is given to the hardware which is being developed, an abstract model, programming language considerations, research considerations, research objectives, Ada tasks, Ada packages, the Ada model, the mapping of the model to the hardware, a precompiler example, and the advantages of Ada.

Collins, W. R.↗

NASA NTRS1981

Formal semantic specifications as implementation blueprints for real-time programming languages

Formal definitions of language and system semantics provide highly desirable checks on the correctness of implementations of programming languages and their runtime support systems. If these definitions can give concrete guidance to the implementor, major increases in implementation accuracy and decreases in implementation effort can be achieved. It is shown that of the wide variety of available methods the Hgraph (hypergraph) definitional technique (Pratt, 1975), is best suited to serve as such an implementation blueprint. A discussion and example of the Hgraph technique is presented, as well as an overview of the growing body of implementation experience of real-time languages based on Hgraph semantic definitions.

Feyock, S.↗

NASA NTRS1977

The development of a multi-target compiler-writing system for flight software development

A wide variety of systems designed to assist the user in the task of writing compilers has been developed. A survey of these systems reveals that none is entirely appropriate to the purposes of the MUST project, which involves the compilation of one or at most a small set of higher-order languages to a wide variety of target machines offering little or no software support. This requirement dictates that any compiler writing system employed must provide maximal support in the areas of semantics specification and code generation, the areas in which existing compiler writing systems as well as theoretical underpinnings are weakest. This paper describes an ongoing research and development effort to create a compiler writing system which will overcome these difficulties, thus providing a software system which makes possible the fast, trouble-free creation of reliable compilers for a wide variety of target computers.

Feyock, S.↗