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All sourcesNASA NTRSDOE OSTI
NASA NTRS1987

MPP parallel forth

Massively Parallel Processor (MPP) Parallel FORTH is a derivative of FORTH-83 and Unified Software Systems' Uni-FORTH. The extension of FORTH into the realm of parallel processing on the MPP is described. With few exceptions, Parallel FORTH was made to follow the description of Uni-FORTH as closely as possible. Likewise, the parallel FORTH extensions were designed as philosophically similar to serial FORTH as possible. The MPP hardware characteristics, as viewed by the FORTH programmer, is discussed. Then a description is presented of how parallel FORTH is implemented on the MPP.

Dorband, John E.↗
NASA NTRS1987

Analysis and synthesis of abstract data types through generalization from examples

The discovery of general patterns of behavior from a set of input/output examples can be a useful technique in the automated analysis and synthesis of software systems. These generalized descriptions of the behavior form a set of assertions which can be used for validation, program synthesis, program testing and run-time monitoring. Describing the behavior is characterized as a learning process in which general patterns can be easily characterized. The learning algorithm must choose a transform function and define a subset of the transform space which is related to equivalence classes of behavior in the original domain. An algorithm for analyzing the behavior of abstract data types is presented and several examples are given. The use of the analysis for purposes of program synthesis is also discussed.

Wild, Christian↗
NASA NTRS1985

KSC Space Station Operations Language (SSOL)

The Space Station Operations Language (SSOL) will serve a large community of diverse users dealing with the integration and checkout of Space Station modules. Kennedy Space Center's plan to achieve Level A specification of the SSOL system, encompassing both its language and its automated support environment, is presented in the format of a briefing. The SSOL concept is a collection of fundamental elements that span languages, operating systems, software development, software tools and several user classes. The approach outlines a thorough process that combines the benefits of rapid prototyping with a coordinated requirements gathering effort, yielding a Level A specification of the SSOL requirements.

Source record↗
NASA NTRS1986

Performance measurements of a data link protocol

The end-to-end performance of a program implementing IEEE Std 802.2 logical link control protocol, which provides virtual circuit and datagram service and which constitutes the top sublayer of the data link layer of the reference model for Local Area Networks is studied. The measurements of relative execution times of various functions required in transferring data, over virtual circuits or as datagrams, showed that most of the program execution time is spent in a few relatively low-level functions. One of these functions performs block movement of data in memory, and two other functions provide access to various queues. Based on this result, two alternative versions of the program which move data efficiently were written and measured. In this paper the results of the study are reported and their impact on designing hardware and software systems for a network interface are discussed.

Kanakia, Hemant↗
NASA NTRS1986

GRO attitude control and determination

Design features of the attitude control and determination (ACAD) system for the Gamma Ray Observatory (GRO) that will eventually be launched on the Shuttle are described. A tabulation of the ACAD system components is provided and the various standby and normal pointing operational modes of the system are summarized. The system software and sensors will maintain a quaternion model of the GRO attitude on the bases of kinematic equations and inertial data. The software is standardized and has previously been used on the Solar Maximum Mission and Landsat-D. Details of the processing components, redundant electronics for sensor processing, data handling and actuator control are outlined and illustrated with block diagrams. Tests applied to validate the ACAD design are outlined, as are ground support which will be implemented once the GRO is launched.

Jerkovsky, W.↗
NASA NTRS1986

Computational mechanics - Advances and trends; Proceedings of the Session - Future directions of Computational Mechanics of the ASME Winter Annual Meeting, Anaheim, CA, Dec. 7-12, 1986

The papers contained in this volume provide an overview of the advances made in a number of aspects of computational mechanics, identify some of the anticipated industry needs in this area, discuss the opportunities provided by new hardware and parallel algorithms, and outline some of the current government programs in computational mechanics. Papers are included on advances and trends in parallel algorithms, supercomputers for engineering analysis, material modeling in nonlinear finite-element analysis, the Navier-Stokes computer, and future finite-element software systems.

Noor, Ahmed K.↗
NASA NTRS1987

Interdisciplinary analysis procedures in the modeling and control of large space-based structures

The paper describes a computer software system called the Integrated Multidisciplinary Analysis Tool, IMAT, that has been developed at NASA Langley Research Center. IMAT provides researchers and analysts with an efficient capability to analyze satellite control systems influenced by structural dynamics. Using a menu-driven interactive executive program, IMAT links a relational database to commercial structural and controls analysis codes. The paper describes the procedures followed to analyze a complex satellite structure and control system. The codes used to accomplish the analysis are described, and an example is provided of an application of IMAT to the analysis of a reference space station subject to a rectangular pulse loading at its docking port.

Cooper, Paul A.↗
NASA NTRS1988

Input/Output Subroutine Library Program

Efficient, easy-to-use program moved easily to different computers. Purpose of NAVIO, Input/Output Subroutine Library, provides input/output package of software for FORTRAN programs that is portable, efficient, and easy to use. Implemented as hierarchy of libraries. At bottom is very small library containing only non-portable routines called "I/O Kernel." Design makes NAVIO easy to move from one computer to another, by simply changing kernel. NAVIO appropriate for software system of almost any size wherein different programs communicate through files.

Collier, James B.↗
NASA NTRS1987

Analysis and synthesis of abstract data types through generalization from examples

The discovery of general patterns of behavior from a set of input/output examples can be a useful technique in the automated analysis and synthesis of software systems. These generalized descriptions of the behavior form a set of assertions which can be used for validation, program synthesis, program testing, and run-time monitoring. Describing the behavior is characterized as a learning process in which the set of inputs is mapped into an appropriate transform space such that general patterns can be easily characterized. The learning algorithm must chose a transform function and define a subset of the transform space which is related to equivalence classes of behavior in the original domain. An algorithm for analyzing the behavior of abstract data types is presented and several examples are given. The use of the analysis for purposes of program synthesis is also discussed.

Wild, Christian↗
NASA NTRS1987

Effectiveness of back-to-back testing

Three models of back-to-back testing processes are described. Two models treat the case where there is no intercomponent failure dependence. The third model describes the more realistic case where there is correlation among the failure probabilities of the functionally equivalent components. The theory indicates that back-to-back testing can, under the right conditions, provide a considerable gain in software reliability. The models are used to analyze the data obtained in a fault-tolerant software experiment. It is shown that the expected gain is indeed achieved, and exceeded, provided the intercomponent failure dependence is sufficiently small. However, even with the relatively high correlation the use of several functionally equivalent components coupled with back-to-back testing may provide a considerable reliability gain. Implications of this finding are that the multiversion software development is a feasible and cost effective approach to providing highly reliable software components intended for fault-tolerant software systems, on condition that special attention is directed at early detection and elimination of correlated faults.

Vouk, Mladen A.↗
NASA NTRS1988

Comprehensive rotorcraft analysis methods

The development and application of comprehensive rotorcraft analysis methods in the field of rotorcraft technology are described. These large scale analyses and the resulting computer programs are intended to treat the complex aeromechanical phenomena that describe the behavior of rotorcraft. They may be used to predict rotor aerodynamics, acoustic, performance, stability and control, handling qualities, loads and vibrations, structures, dynamics, and aeroelastic stability characteristics for a variety of applications including research, preliminary and detail design, and evaluation and treatment of field problems. The principal comprehensive methods developed or under development in recent years and generally available to the rotorcraft community because of US Army Aviation Research and Technology Activity (ARTA) sponsorship of all or part of the software systems are the Rotorcraft Flight Simulation (C81), Dynamic System Coupler (DYSCO), Coupled Rotor/Airframe Vibration Analysis Program (SIMVIB), Comprehensive Analytical Model of Rotorcraft Aerodynamics and Dynamics (CAMRAD), General Rotorcraft Aeromechanical Stability Program (GRASP), and Second Generation Comprehensive Helicopter Analysis System (2GCHAS).

Stephens, Wendell B.↗
NASA NTRS1988

Computational structural mechanics for engine structures

The computational structural mechanics (CSM) program at Lewis encompasses the formulation and solution of structural mechanics problems and the development of integrated software systems to computationally simulate the performance, durability, and life of engine structures. It is structured to supplement, complement, and, whenever possible, replace costly experimental efforts. Specific objectives are to investigate unique advantages of parallel and multiprocessing for reformulating and solving structural mechanics and formulating and solving multidisciplinary mechanics and to develop integrated structural system computational simulators for predicting structural performance, evaluating newly developed methods, and identifying and prioritizing improved or missing methods.

Chamis, Christos C.↗
NASA NTRS1987

An automated system for terrain database construction

An automated Terrain Database Preparation System (TDPS) for the construction and editing of terrain databases used in computerized wargaming simulation exercises has been developed. The TDPS system operates under the TAE executive, and it integrates VICAR/IBIS image processing and Geographic Information System software with CAD/CAM data capture and editing capabilities. The terrain database includes such features as roads, rivers, vegetation, and terrain roughness.

Johnson, L. F.↗
NASA NTRS1988

Image processing software for imaging spectrometry data analysis

Imaging spectrometers simultaneously collect image data in hundreds of spectral channels, from the near-UV to the IR, and can thereby provide direct surface materials identification by means resembling laboratory reflectance spectroscopy. Attention is presently given to a software system, the Spectral Analysis Manager (SPAM) for the analysis of imaging spectrometer data. SPAM requires only modest computational resources and is composed of one main routine and a set of subroutine libraries. Additions and modifications are relatively easy, and special-purpose algorithms have been incorporated that are tailored to geological applications.

Mazer, Alan↗
NASA NTRS1988

An application of MSC/NASTRAN in the interdisciplinary analysis of large space-based structures

The Integrated Multidisciplinary Analysis Tool (IMAT), a computer software system developed at NASA Langley to analyze and simulate the dynamics of space-structure/control-system interactions, is described, and its application to the MAST problem (a 60-m truss with fundamental frequency less than 200 mHz and equipped with linear proof-mass actuators, to be deployed from the Space Shuttle as part of COFS-I flight experiment) is demonstrated. Particular attention is given to the IMAT procedures which facilitate the use of the MCS/NASTRAN code to recover physical results from time-domain state-space solutions obtained with an FEM control-design code. Diagrams, drawings, and graphs are provided.

Stockwell, Alan E.↗
NASA NTRS1988

Understanding of and applications for robot vision guidance at KSC

The primary thrust of robotics at KSC is for the servicing of Space Shuttle remote umbilical docking functions. In order for this to occur, robots performing servicing operations must be capable of tracking a swaying Orbiter in Six Degrees of Freedom (6-DOF). Currently, in NASA KSC's Robotic Applications Development Laboratory (RADL), an ASEA IRB-90 industrial robot is being equipped with a real-time computer vision (hardware and software) system to allow it to track a simulated Orbiter interface (target) in 6-DOF. The real-time computer vision system effectively becomes the eyes for the lab robot, guiding it through a closed loop visual feedback system to move with the simulated Orbiter interface. This paper will address an understanding of this vision guidance system and how it will be applied to remote umbilical servicing at KSC. In addition, other current and future applications will be addressed.

Shawaga, Lawrence M.↗
NASA NTRS1989

Managing Data From Signal-Propagation Experiments

Computer programs generate characteristic plots from amplitudes and phases. Software system enables minicomputer to process data on amplitudes and phases of signals received during experiments in ground-mobile/satellite radio propagation. Takes advantage of file-handling capabilities of UNIX operating system and C programming language. Interacts with user, under whose guidance programs in FORTRAN language generate plots of spectra or other curves of types commonly used to characterize signals. FORTRAN programs used to process file-handling outputs into any of several useful forms.

Kantak, A. V.↗
NASA NTRS1988

Automated knowledge generation

The general objectives of the NASA/UCF Automated Knowledge Generation Project were the development of an intelligent software system that could access CAD design data bases, interpret them, and generate a diagnostic knowledge base in the form of a system model. The initial area of concentration is in the diagnosis of the process control system using the Knowledge-based Autonomous Test Engineer (KATE) diagnostic system. A secondary objective was the study of general problems of automated knowledge generation. A prototype was developed, based on object-oriented language (Flavors).

Myler, Harley R.↗