Search NASA⌕ Search

SEARCH · Search NASA

Results for “programming systems”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 955 records · Page 53
All sourcesNASA NTRSDOE OSTI
NASA NTRS1981

PAN AIR: A computer program for predicting subsonic or supersonic linear potential flows about arbitrary configurations using a higher order panel method. Volume 3: Case manual (version 1.0)

Numerous applications of the PAN AIR computer program system are presented. PAN AIR is user-oriented tool for analyzing and/or designing aerodynamic configurations in subsonic or supersonic flow using a technique generally referred to as a higher order panel method. Problems solved include simple wings in subsonic and supersonic flow, a wing-body in supersonic flow, wing with deflected flap in subsonic flow, design of two-dimensional and three-dimensional wings, axisymmetric nacelle in supersonic flow, and wing-canard-tail-nacelle-fuselage combination in supersonic flow.

Medan, R. T.↗
NASA NTRS1984

Static jet noise test results of four 0.35 scale-model QCGAT mixer nozzles

As part of the NASA Quiet Clean General Aviation Turbofan (QCGAT) engine mixer-nozzle exhaust system program, static jet exhaust noise was recorded at microphone angles of 45 to 155 deg relative to the nozzle inlet for a conventional profile coaxial nozzle and three 12-lobed coaxial mixer nozzles. Both flows in all four nozzles are internally mixed before being discharged from a single exhaust nozzle. The conventional profile coaxial nozzle jet noise is compared to the current NASA Lewis coaxial jet noise prediction and after applying an adjustment to the predicted levels based on the ratio of the kinetic energy of the primary and secondary flows, the prediction is within a standard deviation of 0.9 dB of the measured data. The mass average (mixed flow) prediction is also compared to the noise data for the three mixer nozzles with a reasonably good fit after applying another kinetic energy ratio adjustment (standard deviation of 0.7 to 1.5 dB with the measured data). The tests included conditions for the full-scale engine at takeoff (T.O.), cutback (86% T.O.) and approach (67% T.O.).

Groesbeck, D. E.↗
NASA NTRS1984

Characterizing the scientific potential of satellite sensors

Algorithms and software were developed for the correction of coherent noise, scan correlated shift, and the bright target saturation effect in Thematic Mapper imagery. In addition, a package of LANDSAT Assessment System programs was developed to demonstrate the results from TM radiometric characterization and calibration work.

Lee, Y.↗
NASA NTRS1985

Evaluation of expert systems

The only successful applied area of artificial intelligence is that of expert systems, programs which collect and arrange information about the solution of difficult problems in a well-defined and well-circumscribed area, and are then capable of mimicking expert behavior in finding solutions to new problems. NASA intends to investigate the application of this technology to management and control situations in a space station environment, specifically for power, heat, communications, and attitude control, areas where much of the time human management is laborious, repetitive, and eventually error-prone.

Mcanulty, M. A.↗
NASA NTRS1984

Current concepts and future directions of CELSS

The components of a bioregenerative life-support system intended for use in space are described and the requirements for system control are discussed. Concepts of such systems include the use of higher plants and/or micro-algae as sources of oxygen, CO2 absorption, potable water, and food. In order to focus on the specific problem of reservoirs and buffers, bioregenerative life support in space is contrasted to terrestrial ecological concepts. Some of the future directions of the NASA CELSS (controlled ecological life-support system) program are outlined.

Macelroy, R. D.↗
NASA NTRS1984

Advanced Gas Turbine (AGT) powertrain system development for automotive applications report

This report describes progress and work performed during January through June 1984 to develop technology for an Advanced Gas Turbine (AGT) engine for automotive applications. Work performed during the first eight periods initiated design and analysis, ceramic development, component testing, and test bed evaluation. Project effort conducted under this contract is part of the DOE Gas Turbine Highway Vehicle System Program. This program is oriented at providing the United States automotive industry the high-risk long-range techology necessary to produce gas turbine engines for automobiles with reduced fuel consumption and reduced environmental impact. Technology resulting from this program is intended to reach the marketplace by the early 1990s.

Source record↗
NASA NTRS1986

A flightpath overshoot flying qualities metric for the landing task

An analysis was conducted of the attitude and flightpath angle response of configurations used in the Total In-Flight Simulator (TIFS) pitch-rate command systems program. The results show poor correlation between pilot ratings and attitude response and indicate that attitude was not a major influence in the results. A strong correlation was found to exist, however, between the amount of flightpath angle peak overshoot and the pilot ratings. This correlation is similar to the best correlations that have been obtained in recent closed-loop and time-domain analyses but has the advantage of greatly simplified implementation and interpretation.

Berry, D. T.↗
NASA NTRS1986

Optimal airframe synthesis for gust loads

An optimization capability for sizing airframe structures that are subjected to a combination of deterministic and random flight loads was established. The random vibration environment introduces the need for selecting a statistical process that best describes the random loads and permits computation of the dynamic response parameters of interest. Furthermore, it requires a formulation of design constraints that would minimize the conservativeness in the design and retain computational viability. The random loads are treated as a stationary, homogeneous process with a Gaussian probability distribution. The formulation of the analysis problem, the structure of the optimization programming system and a representative numerical example are discussed.

Hajela, P.↗
NASA NTRS1986

Evaluation of a Stirling engine heater bypass with the NASA Lewis nodal-analysis performance code

In support of the U.S. Department of Energy's Stirling Engine Highway Vehicle Systems program, the NASA Lewis Research Center investigated whether bypassing the P-40 Stirling engine heater during regenerative cooling would improve engine performance. The Lewis nodal-analysis Stirling engine computer simulation was used for this investigation. Results for the heater-bypass concept showed no significant improvement in the indicated thermal efficiency for the P-40 Stirling engine operating at full-power and part-power conditions. Optimizing the heater tube length produced a small increase in the indicated thermal efficiency with the heater-bypass concept.

Sullivan, T. J.↗
NASA NTRS1986

A flightpath overshoot flying qualities metric for the landing task

An analysis was conducted of the attitude and flightpath angle response of configurations used in the Total In-Flight Simulator (TIFS) pitch-rate command systems program. The resutls show poor correlation between pilot ratings and attitude response and indicate that attitude was not a major influence in the results. A strong correlation was found to exist, however, between the amount of fightpath angle peak overshoot and the pilot ratings. This correlation is similar to the best correlations that have been obtained in recent closed-loop and time-domain analyses but has the advantage of greatly simplified implementation and interpretation.

Berry, D. T.↗
NASA NTRS1986

An investigation of selected on-orbit satellite servicing issues

The results of three separate investigations performed by Science Applications International Corporation (SAIC) between August 1985 and October 1986 as the second phase of the two-phase Satellite Services System Program Plan contract for the Engineering Directorate of the Lyndon B. Johnson Space Center are discussed. The objectives of the first phase of this contract (reported in SAIC-85/1762) were to determine the potential for servicing a diverse range of spacecraft from the Space Shuttle Orbiter and to assess NASA's role as the catalyst in enabling routine on-orbit servicing. The second area of investigation was prompted by the need to understand satellite servicing requirements in the far term (1995 to 2010) and how results from the first phase of this contract could support these requirements. The mission model developed during the first phase was extended using new data and information from studies which address the later time period. The third area of investigation looked at a new servicing mode which had not been studied previously. This mode involves the on-orbit exchange of very large modules with masses greater than approximately 9,000 kilograms and/or lengths greater than approximately nine meters. The viewgraphs used for the final briefing for each of the three investigations, as presented to NASA are given.

Hoffman, Stephen J.↗
NASA NTRS1987

Parallel VLSI architecture emulation and the organization of APSA/MPP

The Applicative Programming System Architecture (APSA) combines an applicative language interpreter with a novel parallel computer architecture that is well suited for Very Large Scale Integration (VLSI) implementation. The Massively Parallel Processor (MPP) can simulate VLSI circuits by allocating one processing element in its square array to an area on a square VLSI chip. As long as there are not too many long data paths, the MPP can simulate a VLSI clock cycle very rapidly. The APSA circuit contains a binary tree with a few long paths and many short ones. A skewed H-tree layout allows every processing element to simulate a leaf cell and up to four tree nodes, with no loss in parallelism. Emulation of a key APSA algorithm on the MPP resulted in performance 16,000 times faster than a Vax. This speed will make it possible for the APSA language interpreter to run fast enough to support research in parallel list processing algorithms.

Odonnell, John T.↗
NASA NTRS1987

HALOE test and evaluation software

Computer programming, system development and analysis efforts during this contract were carried out in support of the Halogen Occultation Experiment (HALOE) at NASA/Langley. Support in the major areas of data acquisition and monitoring, data reduction and system development are described along with a brief explanation of the HALOE project. Documented listings of major software are located in the appendix.

Edmonds, W.↗
NASA NTRS1988

The JPL trapped mercury ion frequency standard

In order to provide frequency standards for the Deep Space Network (DSN) which are more stable than present-day hydrogen masers, a research task was established under the Advanced Systems Program of the TDA to develop a Hg-199(+) trapped ion frequency standard. The first closed-loop operation of this kind is described. Mercury-199 ions are confined in an RF trap and are state-selected through the use of optical pumping with 194 nm UV light from a Hg-202 discharge lamp. Absorption of microwave radiation at the hyperfine frequency (40.5 GHz) is signaled by atomic fluorescence of the UV light. The frequency of a 40.5 GHz oscillator is locked to a 1.6 Hz wide atomic absorption line of the trapped ions. The measured Allan variance of this locked oscillator is currently gamma sub y (pi) = 4.4 x 10 to the minus 12th/square root of pi for 20 is less than pi is less than 320 seconds, which is better stability than the best commercial cesium standards by almost a factor of 2. This initial result was achieved without magnetic shielding and without regulation of ion number.

Prestage, J. D.↗
NASA NTRS1987

Implementation of RCCL, a robot control C library on a microVAX II

The robot control C library (RCCL), a high-level robot programing system which enables a progammer to employ a set of system calls to specify robot manipulator tasks, is discussed. The general structure of RCCL is described, and the implementation of RCCL on a microVAX II is examined. Proposed extensions and improvements of RCCL relevant to NASA's telerobotic system are addressed.

Lee, Jin S.↗
NASA NTRS1988

Dynamics and control characteristics of a reference Space Station configuration

This paper describes the structural dynamic characteristics of a NASA reference space station configuration as defined in the November 1987 Space Station Program - Systems Engineering and Integration Engineering Data Book. The modes and frequencies of the station below 2.0 Hz were obtained and selected results along with rigid body properties are presented. A three-axis attitude control system using control moment gyros responding to attitude and attitude rate signals is used to regulate the orientation of the station. The stability of the control system with non-collocated sensors is investigated for both compensated and uncompensated control signals. Results from a closed-loop simulation of a commanded attitude change about three axes, and from a closed-loop simulation of the response of the station to an externally applied unit force impulse at the docking port are presented. These simulation results are used to evaluate the possible degree of control/structures interaction which could occur during normal operation of the station.

Sutter, Thomas R.↗
NASA NTRS1988

Orbit lifetime characteristics for Space Station

The factors that influence the orbital lifetime characteristics of the NASA Space Station are discussed. These include altitude, attitude, launch date, ballistic coefficient, and the presence of large articulating solar arrays. Examples from previous program systems studies are presented that illustrate how each factor affects Station orbit lifetime. The effect of atmospheric density models on orbit lifetime predictions is addressed along with the uncertainty of these predictions using current trajectory analysis of the Long Duration Exposure Facility spacecraft. Finally, nominal reboost altitude profiles and fuel requirement considerations are presented for implementing a reboost strategy based on planned Shuttle Orbiter rendezvous strategy and contingency considerations.

Deryder, L.↗