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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

Optimum-AIV: A planning and scheduling system for spacecraft AIV

A project undertaken for the European Space Agency (ESA) is presented. The project is developing a knowledge based software system for planning and scheduling of activities for spacecraft assembly, integration, and verification (AIV). The system extends into the monitoring of plan execution and the plan repair phase. The objectives are to develop an operational kernel of a planning, scheduling, and plan repair tool, called OPTIMUM-AIV, and to provide facilities which will allow individual projects to customize the kernel to suit its specific needs. The kernel shall consist of a set of software functionalities for assistance in initial specification of the AIV plan, in verification and generation of valid plans and schedules for the AIV activities, and in interactive monitoring and execution problem recovery for the detailed AIV plans. Embedded in OPTIMUM-AIV are external interfaces which allow integration with alternative scheduling systems and project databases. The current status of the OPTIMUM-AIV project, as of Jan. 1991, is that a further analysis of the AIV domain has taken place through interviews with satellite AIV experts, a software requirement document (SRD) for the full operational tool was approved, and an architectural design document (ADD) for the kernel excluding external interfaces is ready for review.

Arentoft, M. M.↗
NASA NTRS1990

Machine learning research 1989-90

Multifunctional knowledge bases offer a significant advance in artificial intelligence because they can support numerous expert tasks within a domain. As a result they amortize the costs of building a knowledge base over multiple expert systems and they reduce the brittleness of each system. Due to the inevitable size and complexity of multifunctional knowledge bases, their construction and maintenance require knowledge engineering and acquisition tools that can automatically identify interactions between new and existing knowledge. Furthermore, their use requires software for accessing those portions of the knowledge base that coherently answer questions. Considerable progress was made in developing software for building and accessing multifunctional knowledge bases. A language was developed for representing knowledge, along with software tools for editing and displaying knowledge, a machine learning program for integrating new information into existing knowledge, and a question answering system for accessing the knowledge base.

Porter, Bruce W.↗
NASA NTRS1990

Automatic programming of simulation models

The concepts of software engineering were used to improve the simulation modeling environment. Emphasis was placed on the application of an element of rapid prototyping, or automatic programming, to assist the modeler define the problem specification. Then, once the problem specification has been defined, an automatic code generator is used to write the simulation code. The following two domains were selected for evaluating the concepts of software engineering for discrete event simulation: manufacturing domain and a spacecraft countdown network sequence. The specific tasks were to: (1) define the software requirements for a graphical user interface to the Automatic Manufacturing Programming System (AMPS) system; (2) develop a graphical user interface for AMPS; and (3) compare the AMPS graphical interface with the AMPS interactive user interface.

Schroer, Bernard J.↗
NASA NTRS1991

Executive system software design and expert system implementation

The topics are presented in viewgraph form and include: software requirements; design layout of the automated assembly system; menu display for automated composite command; expert system features; complete robot arm state diagram and logic; and expert system benefits.

Cheryl L Allen↗
NASA NTRS1992

Software Management Environment (SME) installation guide

This document contains installation information for the Software Management Environment (SME), developed for the Systems Development Branch (Code 552) of the Flight Dynamics Division of Goddard Space Flight Center (GSFC). The SME provides an integrated set of management tools that can be used by software development managers in their day-to-day management and planning activities. This document provides a list of hardware and software requirements as well as detailed installation instructions and trouble-shooting information.

Kistler, David↗
NASA NTRS1993

Formalizing structured file services for the data storage and retrieval subsystem of the data management system for Spacestation Freedom

A brief example of the use of formal methods techniques in the specification of a software system is presented. The report is part of a larger effort targeted at defining a formal methods pilot project for NASA. One possible application domain that may be used to demonstrate the effective use of formal methods techniques within the NASA environment is presented. It is not intended to provide a tutorial on either formal methods techniques or the application being addressed. It should, however, provide an indication that the application being considered is suitable for a formal methods by showing how such a task may be started. The particular system being addressed is the Structured File Services (SFS), which is a part of the Data Storage and Retrieval Subsystem (DSAR), which in turn is part of the Data Management System (DMS) onboard Spacestation Freedom. This is a software system that is currently under development for NASA. An informal mathematical development is presented. Section 3 contains the same development using Penelope (23), an Ada specification and verification system. The complete text of the English version Software Requirements Specification (SRS) is reproduced in Appendix A.

Jamsek, Damir A.↗
NASA NTRS1993

A functional description of the Buffered Telemetry Demodulator (BTD)

This article gives a functional description of the buffered telemetry demodulator (BTD), which operates on recorded digital samples to extract the symbols from the received signal. The key advantages of the BTD are as follows: (1) its ability to reprocess the signal to reduce acquisition time; (2) its ability to use future information about the signal and to perform smoothing on past samples; and (3) its minimum transmission bandwidth requirement as each sub carrier harmonic is processed individually. The first application of the BTD would be the Galileo S-band contingency mission, where the signal is so weak that reprocessing to reduce the acquisition time is crucial. Moreover, in the event of employing antenna arraying with full spectrum combining, only the sub carrier harmonics need to be transmitted between sites, resulting in significant reduction in data rate transmission requirements. Software implementation of the BTD is described for various general-purpose computers.

Tsou, H.↗
NASA NTRS1993

LDEF materials data bases

The Long Duration Exposure Facility (LDEF) and the accompanying experiments were composed of and contained a wide variety of materials representing the largest collection of materials flown in low Earth orbit (LEO) and retrieved for ground based analysis to date. The results and implications of the mechanical, thermal, optical, and electrical data from these materials are the foundation on which future LEO space missions will be built. The LDEF Materials Special Investigation Group (MSIG) has been charged with establishing and developing data bases to document these materials and their performance to assure not only that the data are archived for future generations but also that the data are available to the spacecraft user community in an easily accessed, user-friendly form. This paper discusses the format and content of the three data bases developed or being developed to accomplish this task. The hardware and software requirements for each of these three data bases are discussed along with current availability of the data bases. This paper also serves as a user's guide to the MAPTIS LDEF Materials Data Base.

Funk, Joan G.↗
NASA NTRS1992

ROSAT guest investigator program (AO-1). On a search for coronal x ray emissions from white dwarfs

We have suggested that cool magnetic white dwarfs may be sources of X-ray coronal emission and proposed several prominent candidates for this emission. One of these candidates (EG 250) was approved for the C-category observation by the National and International Committee and was observed by ROSAT on April 17, 1991. Unfortunately, the granted exposure time (1071 s) was much shorter than that which was required by theoretical predictions to observe coronal X-ray emission from this object. The tape containing the data was send to us in November 1991. Since then we have analyzed the data visiting the ROSAT Science Center at NASA Goddard Space Flight Center. The analysis of the data taken during this short observation show, as expected, no X-rays. It is our hope that EG 250 will be observed again during the AO-2 phase of pointed observations, as 10,000 s of observing time was granted to V. Trimble for the C-category observation of this star. We have a close contact with Dr. Trimble regarding this matter. Because our all targets (GD 90, KUV 2316-123 and GD 356) proposed for the observation during the AO-2 phase of pointed observations have been approved by the National and International Committee, we have installed the required software at NASA/MSFC to be able to carry out the data analysis in Huntsville. Two of our targets have already been observed (KUV 2316-123 was observed on Dec. 3, 1991 with 10,000 s of the exposure time, and GD 356 was observed on Jan 4, 1992 with 5,000 s of the exposure time). We just received the data and will begin the analysis soon. The results of our analysis will be reported to the scientific community by publishing papers in the Astrophysical Journal Letters. Our intention is to submit a paper when the analysis of the data taken during AO2 is completed. The data taken during the observation of EG 250 will be a part of this paper.

Musielak, Z. E.↗
NASA NTRS1992

Helicopter precision approach capability using the Global Positioning System

The period between 1 July and 31 December, 1992, was spent developing a research plan as well as a navigation system document and flight test plan to investigate helicopter precision approach capability using the Global Positioning System (GPS). In addition, all hardware and software required for the research was acquired, developed, installed, and verified on both the test aircraft and the ground-based reference station.

Kaufmann, David N.↗
NASA NTRS1993

Dust content of a hydrogen rich, low surface brightness galaxy and the luminosity history of 3C273

This project consists of a 30,000 second PSPC observation of the Giovanelli-Haynes Cloud in an attempt to detect light emitted by 3C273 which has been reflected by the cloud, and incidentally search the cloud for other sources of X-ray emission. The observation was carried out by ROSAT on Dec. 25, 1992 and the data was received by the P.I. in late March of 1993. We have examined the data and determined that the observation's background level, astrometry, etc. are acceptable. We have also detected diffuse emission from the direction of the Giovanelli-Haynes Cloud. Determination of the origin of this emission, by examining its morphology in relation to that of the radio map and the object's geometric relation with 3C273, requires software implementation of specialized algorithms. However, the most dramatic observation in the field is a potentially new population of discrete soft X-ray sources associated with dwarf galaxies.

Hamilton, Thomas T.↗
NASA NTRS1994

Parallel Computing for Probabilistic Response Analysis of High Temperature Composites

The objective of this Phase I research was to establish the required software and hardware strategies to achieve large scale parallelism in solving PCM problems. To meet this objective, several investigations were conducted. First, we identified the multiple levels of parallelism in PCM and the computational strategies to exploit these parallelisms. Next, several software and hardware efficiency investigations were conducted. These involved the use of three different parallel programming paradigms and solution of two example problems on both a shared-memory multiprocessor and a distributed-memory network of workstations.

Sues, R. H.↗
NASA NTRS1993

LDEF materials special investigation group's data bases

The Long Duration Exposure Facility (LDEF) was composed of and contained a wide array of materials, representing the largest collection of materials flown for space exposure and returned for ground-based analyses to date. The results and implications of the data from these materials are the foundation on which future space missions will be built. The LDEF Materials Special Investigation Group (MSIG) has been tasked with establishing and developing data bases to document these materials and their performance to assure not only that the data are archived for future generations but also that the data are available to the space user community in an easily accessed, user-friendly form. The format and content of the data bases developed or being developed to accomplish this task are discussed. The hardware and software requirements for each of the three data bases are discussed along with current availability of the data bases.

Strickland, John W.↗
NASA NTRS1995

Global flowfield about the V-22 Tiltrotor Aircraft

The Chimera overset grid method is reviewed and discussed in the context of a method of solution and analysis of unsteady three-dimensional viscous flows. The state of maturity of the various pieces of support software required to use the approach is discussed. A variety of recent applications of the method is presented. Current limitations of the approach are identified.

Meakin, Robert L.↗
NASA NTRS1995

Learning In networks

Intelligent systems require software incorporating probabilistic reasoning, and often times learning. Networks provide a framework and methodology for creating this kind of software. This paper introduces network models based on chain graphs with deterministic nodes. Chain graphs are defined as a hierarchical combination of Bayesian and Markov networks. To model learning, plates on chain graphs are introduced to model independent samples. The paper concludes by discussing various operations that can be performed on chain graphs with plates as a simplification process or to generate learning algorithms.

Buntine, Wray L.↗
NASA NTRS1996

The Chimera Method of Simulation for Unsteady Three-Dimensional Viscous Flow

The Chimera overset grid method is reviewed and discussed in the context of a method of solution and analysis of unsteady three-dimensional viscous flows. The state of maturity of the various pieces of support software required to use the approach is discussed. A variety of recent applications of the method is presented. Current limitations of the approach are defined.

Meakin, Robert L.↗
NASA NTRS1995

Generalized Support Software: Domain Analysis and Implementation

For the past five years, the Flight Dynamics Division (FDD) at NASA's Goddard Space Flight Center has been carrying out a detailed domain analysis effort and is now beginning to implement Generalized Support Software (GSS) based on this analysis. GSS is part of the larger Flight Dynamics Distributed System (FDDS), and is designed to run under the FDDS User Interface / Executive (UIX). The FDD is transitioning from a mainframe based environment to systems running on engineering workstations. The GSS will be a library of highly reusable components that may be configured within the standard FDDS architecture to quickly produce low-cost satellite ground support systems. The estimates for the first release is that this library will contain approximately 200,000 lines of code. The main driver for developing generalized software is development cost and schedule improvement. The goal is to ultimately have at least 80 percent of all software required for a spacecraft mission (within the domain supported by the GSS) to be configured from the generalized components.

Stark, Mike↗