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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 397 records · Page 22
All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

Real gas scale effects on hypersonic laminar boundary-layer parameters including effects of entropy-layer swallowing

Inviscid and viscous (laminar boundary-layer) flow-field calculations under perfect gas hypersonic wind tunnel and equilibrium real gas flight conditions are presented for the windward centerline of the Rockwell International 139 Space Shuttle Orbiter at a 30-deg angle of attack. Correlation parameters for laminar boundary-layer edge quantities and surface heat transfer are developed which properly account for entropy-layer-swallowing effects under both real and perfect gas conditions. Some implications of the proposed correlation parameters on boundary-layer transition are discussed.

Adams, J. C., Jr.↗
NASA NTRS1976

An investigation of the effects of mass loss, shape change and real gas aerodynamics on a Jovian atmospheric reconstruction experiment

A survey of the effects of mass loss, shape change and real-gas aerodynamics on a Jovian atmospheric reconstruction experiment is carried out. Techniques used to reconstruct atmospheric profiles from entry probe measurements are discussed and some of the parameters which affect their accuracy are identified. Trajectory analyses and real-gas, radiatively-coupled flow field analyses (which include the effects of mass loss and shape change) are carried out for several candidate probe configurations. From these analyses, uncertainties in the atmospheric reconstruction procedure are estimated. Finally, the prospects for reducing these uncertainties by optimizing probe configuration and by instrumentation of the probe heat shield to measure actual shape change are considered.

Walberg, G. D.↗
NASA NTRS1976

Investigation of a Real-time Processing System for the NASA Multifrequency Microwave Radiometer

A study was conducted to investigate the data reduction and processing requirements for the multifrequency microwave radiometer system (MFMR). The objectives were to develop and evaluate algorithms and processing techniques which might provide for dedicated real time or near real time data processing and to develop a configuration design and processor recommendation to accomplish the data reduction. An analysis of the required data reduction and calibration equations was included along with the identification of sources of error which may be present in the (MFMR) data. The definition and evaluation of the significance of effects introduced by aircraft perturbation was given.

Source record↗
NASA NTRS1977

Development and verification of real-time, hybrid computer simulation of F100-PW-100(3) turbofan engine

A real time, hybrid computer simulation of a turbofan engine is described. Controls research programs involving that engine are supported by the simulation. The real time simulation is shown to match the steady state and transient performance of the engine over a wide range of flight conditions and power settings. The simulation equations, FORTRAN listing, and analog patching diagrams are included.

Szuch, J. R.↗
NASA NTRS1977

Computer considerations for real time simulation of a generalized rotor model

Scaled equations were developed to meet requirements for real time computer simulation of the rotor system research aircraft. These equations form the basis for consideration of both digital and hybrid mechanization for real time simulation. For all digital simulation estimates of the required speed in terms of equivalent operations per second are developed based on the complexity of the equations and the required intergration frame rates. For both conventional hybrid simulation and hybrid simulation using time-shared analog elements the amount of required equipment is estimated along with a consideration of the dynamic errors. Conventional hybrid mechanization using analog simulation of those rotor equations which involve rotor-spin frequencies (this consititutes the bulk of the equations) requires too much analog equipment. Hybrid simulation using time-sharing techniques for the analog elements appears possible with a reasonable amount of analog equipment. All-digital simulation with affordable general-purpose computers is not possible because of speed limitations, but specially configured digital computers do have the required speed and consitute the recommended approach.

Howe, R. M.↗
NASA NTRS1977

Feasibility study of microprocessor systems suitable for use in developing a real-time for the 4.75 GHz scatterometer

A class of signal processors suitable for the reduction of radar scatterometer data in real time was developed. The systems were applied to the reduction of single polarized 13.3 GHz scatterometer data and provided a real time output of radar scattering coefficient as a function of incident angle. It was proposed that a system for processing of C band radar data be constructed to support scatterometer system currently under development. The establishment of a feasible design approach to the development of this processor system utilizing microprocessor technology was emphasized.

Source record↗
NASA NTRS1976

Crack growth in Ti-8Al-1Mo-1V with real-time and accelerated flight-by-flight loading

Crack growth in Ti-8Al-1Mo-1V was measured and calculated for real-time and accelerated simulations of supersonic airplane loading and heating. Crack-growth rates calculated on the assumption that an entire flight could be represented by a single cycle predicted the experimental rates poorly. Calculated crack-growth rates were slower than the experimental rates for all tests with flight-by-flight loading. For room-temperature accelerated tests, the calculated rates agreed well with the experimental rates; but the calculations became progressively less accurate for progressively more complex test conditions (tests that included elevated temperature). Calculations of crack growth using the crack-closure concept can probably be improved through study of crack-opening stresses using finite-element models that account for variable-amplitude loading, residual stresses, and temperature effects. The calculations of crack growth could also be improved through detailed studies of material properties and interactions among stress, temperature, and time as appropriate for the real-time operating conditions of a supersonic transport airplane.

Imig, L. A.↗
NASA NTRS1975

Real-time detection and data acquisition system for the left ventricular outline

The paper describes the design and capabilities of a computer-interfaced angiocardiographic automated border recognizer for real-time detection and data acquisition regarding the left ventricular outline. The contour detection is based on a thresholding technique that uses an analog comparator to compare the video signal with a constant reference level, which can be used satisfactorily only if the brightness level is roughly constant along a ventricular border. The use of dynamic reference level is described for achieving a marked improvement by having the reference level dynamically adjusted according to local brightness levels on a line-to-line basis. Also discussed are the features of the computer interface designed and implemented for the real-time on-line storage of the obtained border coordinates. Results to date indicate that the system provides an accurate left ventricular contour even in pictures with relatively low contrast. Application of the threshold detection technique to echocardiography is briefly discussed.

Reiber, J. H. C.↗
NASA NTRS1977

The correlation of laboratory test results with behavior in real fires

Laboratory tests have been condemned as misleading because they do not always predict behavior in real fires. General condemnation seems unjustified in the light of available data. Many laboratory tests are employed with the purpose of eliminating fire hazard by preventing ignition, and fires that did not happen provide no data for correlation. Correlations are sometimes attempted between a laboratory test which emphasizes one fire response characteristic and a fire situation in which the hazard relates to a different fire response characteristic. Correlations may fail in particular cases, but in general, something less likely to burn or emit undesirable products in a laboratory test is less likely to be a hazard in a real fire.

Hilado, C. J.↗
NASA NTRS1977

Real-time testing of titanium sheet and extrusion coupon specimens subjected to Mach 2.7 supersonic cruise aircraft wing stresses and temperatures

The accuracy of three accelerated flight-by-flight test methods for material selection, and fatigue substantiation of supersonic cruise aircraft structure was studied. The real time stresses and temperatures applied to the specimens were representative of the service conditions in the lower surface of a Mach 2.7 supersonic cruise aircraft wing root structure. Each real time flight lasted about 65 minutes, including about one hour at (500 F) in the cruise condition. Center notched coupon specimens from six titanium materials were tested: mill-annealed, duplex-annealed, and triplex-annealed Ti-8Al-1Mo-1V sheets; mill-annealed Ti-8Al-1Mo-1V extrusion; mill-annealed Ti-6Al-4V sheet; and solution-treated and aged Ti-6Al-4V extrusion. For duplex-annealed Ti-8Al-1Mo-1V sheet, specimens with single spotweld were also tested. The test results were studied in conjunction with other related data from the literature for: material selection, structural fabrication, fatigue resistance of supersonic cruise aircraft structure, and fatigue test acceleration procedures for supersonic cruise aircraft.

Lunde, T.↗
NASA NTRS1977

Real-time and accelerated outdoor endurance testing of solar cells

Real-time and accelerated outdoor endurance testing was performed on a variety of samples of interest to the National Photovoltaic Conversion Program. The real-time tests were performed at seven different sites and the accelerated tests were performed at one of those sites in the southwestern United States. The purpose of the tests were to help evaluate the lifetime of photovoltaic systems. Three types of samples were tested; transmission samples of possible cover materials, sub-modules constructed using these materials attached to solar cells, and solar cell modules produced by the manufacturers for the ERDA program. Results indicate that suitable cover materials are glass, FEP-A and PFA. Dirt accumulation and cleanability are important factors in the selection of solar cell module covers and encapsulants.

Forestieri, A. F.↗
NASA NTRS1978

Real time digital propulsion system simulation for manned flight simulators

A real time digital simulation of a STOL propulsion system was developed which generates significant dynamics and internal variables needed to evaluate system performance and aircraft interactions using manned flight simulators. The simulation ran at a real-to-execution time ratio of 8.8. The model was used in a piloted NASA flight simulator program to evaluate the simulation technique and the propulsion system digital control. The simulation is described and results shown. Limited results of the flight simulation program are also presented.

Mihaloew, J. R.↗
NASA NTRS1979

Low-level processing for real-time image analysis

A system that detects object outlines in television images in real time is described. A high-speed pipeline processor transforms the raw image into an edge map and a microprocessor, which is integrated into the system, clusters the edges, and represents them as chain codes. Image statistics, useful for higher level tasks such as pattern recognition, are computed by the microprocessor. Peak intensity and peak gradient values are extracted within a programmable window and are used for iris and focus control. The algorithms implemented in hardware and the pipeline processor architecture are described. The strategy for partitioning functions in the pipeline was chosen to make the implementation modular. The microprocessor interface allows flexible and adaptive control of the feature extraction process. The software algorithms for clustering edge segments, creating chain codes, and computing image statistics are also discussed. A strategy for real time image analysis that uses this system is given.

Eskenazi, R.↗
NASA NTRS1978

Real time mass flow computer for Arc Jet Wind Tunnel

Experiments at the Arc Jet Tunnel at Ames Research Center have typical run times of 5-10 sec during which the test model is subjected to an environment simulating reentry into Jupiter. Previous real-time determination of mass flow required off-line manual computations from taped or strip chart data. The present paper describes a computer which provides personnel with real-time computations of mass flow. Using an 8-bit microprocessor and standard TTL interface circuitry, the unit interrogates temperature and pressure instruments with other parameters to compute mass flow.

Vidal, J.↗
NASA NTRS1978

Real-time synthetic aperture radar data processing for space applications

Range and azimuth correlation in the time domain using current state-of-the-art CCD LSI technology provides a potentially practical means of achieving real-time pipeline processing of SAR images for future space missions. The proposed range correlator approach, using already demonstrated CCD transversal filtering techniques, will require very little power: less than 10 watts per Seasat-type 20-km processing module. The azimuth correlator architecture is considerably more demanding since it requires a large number of parallel chips (1020 for a Seasat-type 20-km module) to achieve a real-time processing capability.

Arens, W. E.↗
NASA NTRS1979

Binary classification of real sequences by discrete-time systems

This paper considers a novel approach to coding or classifying sequences of real numbers through the use of (generally nonlinear) finite-dimensional discrete-time systems. This approach involves a finite-dimensional discrete-time system (which we call a real acceptor) in cascade with a threshold type device (which we call a discriminator). The proposed classification scheme and the exact nature of the classification problem are described, along with two examples illustrating its applicability. Suggested approaches for further research are given.

Kaliski, M. E.↗
NASA NTRS1979

Real-time ISEE data system

A real-time ISEE data system directed toward predicting geomagnetic substorms and storms is discussed. Such a system may allow up to 60+ minutes advance warning of magnetospheric substorms and up to 30 minute warnings of geomagnetic storms (and other disturbances) induced by high-speed streams and solar flares. The proposed system utilizes existing capabilities of several agencies (NASA, NOAA, USAF), and thereby minimizes costs. This same concept may be applicable to data from other spacecraft, and other NASA centers; thus, each individual experimenter can receive quick-look data in real time at his or her base institution.

Tsurutani, B. T.↗
NASA NTRS1980

Development and evaluation of a general aviation real world noise simulator

An acoustic playback system is described which realistically simulates the sounds experienced by the pilot of a general aviation aircraft during engine idle, take-off, climb, cruise, descent, and landing. The physical parameters of the signal as they appear in the simulator environment are compared to analogous parameters derived from signals recorded during actual flight operations. The acoustic parameters of the simulated and real signals during cruise conditions are within plus or minus two dB in third octave bands from 0.04 to 4 kHz. The overall A-weighted levels of the signals are within one dB of signals generated in the actual aircraft during equivalent maneuvers. Psychoacoustic evaluations of the simulator signal are compared with similar measurements based on transcriptions of actual aircraft signals. The subjective judgments made by human observers support the conclusion that the simulated sound closely approximates transcribed sounds of real aircraft.

Galanter, E.↗