Digital computer analysis and design of a subreflector of complex shape
Digital computer technique for computing scattered pattern of complex hyperboloid subreflector in Cassegrain antenna feed systems
Ludwig, A.↗
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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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Coding - An engineering tool for the digital telemetry link
Digital coding techniques for data telemetry links
Muller, R. M.↗
Digital FM - Tutorial.
Digital FM techniques, signal spectral properties, discrimination detection, phenomenological model, etc
Salz, J.↗
Rocket trajectory optimization by a second- order numerical technique.
Multistage rocket trajectories optimized by second order numerical technique and digital computer program, considering coasting, vacuum flight and transition times
Kelley, H. J.↗
Recent improvements in the analysis of surface wave observations.
Surface wave study techniques, discussing digital moving window analysis of group and phase velocity and use of time variable filters
Dziewonski, A.↗
Computer-aided design of feedback control systems with plant parameter variations
Improving feedback control design by using digital computer techniques
Lewis, H. Z.↗
Digital processing of the Mariner 6 and 7 pictures
Digital computer techniques for Mars surface imagery systematic video data distortions quantification and correction onboard Mariner 6 and 7
Dunne, J. A.↗
Developments and applications of real-time high resolution mass spectrometry
Real time high resolution mass spectroscopy using digital computer techniques for data acquisition, processing and presentation
Burlingame, A. L.↗
Preprocessing of multispectral data and simulation of ERTS data channels to make computer terrain maps of a Yellowstone National Park test site
The possibility of improving the accuracy of terrain classification by preprocessing spectral data was investigated. Terrain maps were made using the following techniques: 1) preprocessing by scan angle function transformation, using the computer-selected best set of three channels; and 2) preprocessing by ratio transformation, using the specified ERTS data channels, simulated by fitting the spectral response of each of the 12 data channels to the ERTS channels by a set of weighting coefficients. By using a simple technique during printout, the maps were produced in color. The normalized scan angle function transformation resulted in the most accurate classification. The best ratio transformation for the Yellowstone Park data was the ratio of each channel to the sum of all channels. A supervised training program involving maximum likelihood decision for selecting the best spectrometer channels and similar techniques for digitizing the data of the analog magnetic tapes were used. Cloud shadows were recognized in addition to eight classes of terrain. Preprocessing of data resulted in more accurate maps, required fewer training areas (hence less preparation and computer time), and enabled much of the area formerly classified as shadow to be reclassified according to actual terrain type.
Smedes, H. W.↗
Fixed base simulator study of an externally blown flap STOL transport airplane during approach and landing
A fixed-base simulator study was conducted to determine the flight characteristics of a representative STOL transport having a high wing and equipped with an external-flow jet flap in combination with four high-bypass-ratio fan-jet engines during the approach and landing. Real-time digital simulation techniques were used. The computer was programed with equations of motion for six degrees of freedom and the aerodynamic inputs were based on measured wind-tunnel data. A visual display of a STOL airport was provided for simulation of the flare and touchdown characteristics. The primary piloting task was an instrument approach to a breakout at a 200-ft ceiling with a visual landing.
Grantham, W. D.↗
Geometrical factor and directional response of single and multi-element particle telescopes.
After a general treatment of the gathering power of particle telescopes, exact formulae are presented for the geometrical factor and directional response of multielement cylindrically symmetric telescopes with circular or rectangular cross sections. Some useful approximations to these formulae are given. For the gathering power in arbitrary geometries, there is a discussion of applicable digital computer techniques focusing particularly on a Monte Carlo method.
Sullivan, J. D.↗
Digital image processing for the rectification of television camera distortions.
All television systems introduce distortions into the imagery they record which influence the results of quantitative photometric and geometric measurements. Digital computer techniques provide a powerful approach to the calibration and rectification of these systematic effects. Nonlinear as well as linear problems can be attacked with flexibility and precision. Methods which have been developed and applied for the removal of structured system noises and the correction of photometric, geometric, and resolution distortions in vidicon systems are briefly described. Examples are given of results derived primarily from the Mariner Mars 1969 television experiment.
Rindfleisch, T. C.↗
Analysis and synthesis of distributed-lumped-active networks by digital computer
The use of digital computational techniques in the analysis and synthesis of DLA (distributed lumped active) networks is considered. This class of networks consists of three distinct types of elements, namely, distributed elements (modeled by partial differential equations), lumped elements (modeled by algebraic relations and ordinary differential equations), and active elements (modeled by algebraic relations). Such a characterization is applicable to a broad class of circuits, especially including those usually referred to as linear integrated circuits, since the fabrication techniques for such circuits readily produce elements which may be modeled as distributed, as well as the more conventional lumped and active ones.
Source record↗
Simulation of decelerating landing approaches on an externally blown flap STOL transport airplane
A fixed-base simulator program was conducted to define the problems and methods for solution associated with performing decelerating landing approaches on a representative STOL transport having a high wing and equipped with an external-flow jet flap in combination with four high-bypass-ratio fan-jet engines. Real-time digital simulation techniques were used. The computer was programed with equations of motion for six degrees of freedom and the aerodynamic inputs were based on measured wind-tunnel data. The pilot's task was to capture the localizer and the glide slope and to maintain them as closely as possible while decelerating from an initial airspeed of 140 knots to a final airspeed of 75 knots, while under IFR conditions.
Grantham, W. D.↗
A comparison of two methods of extracting stability derivatives from flight test data
Two methods for extracting stability derivatives from flight data are compared. A modified Newton-Raphson quasilinearization minimization technique and a digital-analog (hybrid) matching technique were used to analyze the same data maneuvers obtained from two aircraft. About 70 maneuvers from an F-111E aircraft were analyzed over a Mach number range of 0.3 to 2.0 and an angle of attack range of 3 to 19 degrees. About 20 maneuvers were analyzed for the X-24A lifting body at Mach numbers of 0.5, 0.8, and 0.9, and an angle of attack range of 4 to 13 degrees. Stability derivatives were extracted from these maneuvers and the results from the two techniques, along with wind tunnel results, were compared.
Kirsten, P. W.↗
Simulator study of minimum acceptable level of longitudinal stability for a representative STOL configuration during landing approach
A fixed-base simulator study was conducted to determine the minimum acceptable level of longitudinal stability for a representative turbofan STOL (short take-off and landing) transport airplane during the landing approach. Real-time digital simulation techniques were used. The computer was programed with equations of motion for six degrees of freedom, and the aerodynamic inputs were based on measured wind-tunnel data. The primary piloting task was an instrument approach to a breakout at a 60-m (200-ft) ceiling.
Grantham, W. D.↗
Evaluation of digitally corrected ERTS imagery
Utilizing all digital processing techniques, precision rectified ERTS multispectral imagery have been produced. Precision geometric correction is accomplished by: (1) utilizing a low order piecewise approximation to the image distortions; (2) incorporating spacecraft attitude refinement derived from ground control points utilized in a Kalman filter; (3) utilizing interpolation techniques which preserve value and slope continuity in the image data. Imagery produced is represented in a UTM projection, and has been evaluated for precision by statistical and analytical methods. Extrapolations to modest size computers indicate good throughput with no sacrifice in precision.
Rifman, S. S.↗
High-accuracy programable square-law detector system
Programable system introduces correction factor to compensate for detector deviation from square-law response. If detector output voltage is V, the corrected output voltage is determined as V corrected = aV squared where 'a' is correction factor. Factor is determined and used automatically with digital computer techniques.
Reid, M. S.↗