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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 559 records · Page 31
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

Results of a remote multiplexer/digitizer unit accuracy and environmental study

A remote multiplexer/digitizer unit (RMDU), a part of the airborne integrated flight test data system, was subjected to an accuracy study. The study was designed to show the effects of temperature, altitude, and vibration on the RMDU. The RMDU was subjected to tests at temperatures from -54 C (-65 F) to 71 C (160 F), and the resulting data are presented here, along with a complete analysis of the effects. The methods and means used for obtaining correctable data and correcting the data are also discussed.

Wilner, D. O.↗
NASA NTRS1977

A procedure for merging land cover/use data from LANDSAT, aerial photography, and map sources: Compatibility, accuracy, and cost. Remote Sensing Project

Regional planning agencies are currently expressing a need for detailed land cover/use information to effectively meet the requirements of various federal programs. Individual data sources have advantages and limitations in fulfilling this need, both in terms of time/cost and technological capability. A methodology has been developed to merge land cover/use data from LANDSAT, aerial photography and map sources to maximize the effective use of a variety of data sources in the provision of an integrated information system for regional analysis. A test of the proposed inventory method is currently under way in four central Michigan townships. This test will evaluate the compatibility, accuracy and cost of the integrated method with reference to inventories developed from a single data source, and determine both the technological feasibility and analytical potential of such a system.

Enslin, W. R.↗
NASA NTRS1977

Least squares polynomial fits and their accuracy

Equations are presented which attempt to fit least squares polynomials to tables of date. It is concluded that much data are needed to reduce the measurement error standard deviation by a significant amount, however at certain points great accuracy is attained.

Lear, W. M.↗
NASA NTRS1977

A procedure for merging land cover/use data from Landsat, aerial photography, and map sources - Compatibility, accuracy and cost

A method is developed to merge land cover/use data from Landsat, aerial photography and map sources into a grid-based geographic information system. The method basically involves computer-assisted categorization of Landsat data to provide certain user-specified land cover categories; manual interpretation of aerial photography to identify other selected land cover/use categories that cannot be obtained from Landsat data; identification of special features from aerial photography or map sources; merging of the interpreted data from all the sources into a computer compatible file under a standardized coding structure; and the production of land cover/use maps, thematic maps, and tabular data. The specific tasks accomplished in producing the merged land cover/use data file and subsequent output products are identified and discussed. It is shown that effective implementation of the merging method is critically dependent on selecting the 'best' data source for each user-specified category in terms of accuracy and time/cost tradeoffs.

Enslin, W. R.↗
NASA NTRS1977

Maximum theoretical angular accuracy of planar and linear arrays of sensors

The maximum theoretical accuracy in the angular location of a radiating object that can be obtained by using a planar or linear array is studied. The elements are assumed to have identical radiation patterns and the complex voltages observed at their ports are assumed to be subject to phase measurement errors, having normal probability density. An optimum scheme for the statistical extraction of the parameters defining the direction is established noting that the presence of thermal noise does not affect the structure of the estimator. Comparisons with the conventional multiple interferometric techniques are made.

Borgiotti, G. V.↗
NASA NTRS1976

Accuracy estimate of the laser rangefinder for Mars rover

A method was developed to determine the accuracy of a rangefinder when errors exist due to the test setup. An analytic procedure was developed to evaluate actual data from a test performed on the laser rangefinder for the Mars rover project.

Ostroski, T.↗
NASA NTRS1977

The effect of bandwidth on filter instrument total ozone accuracy

The effect of the width and shape of the New Zealand filter instrument's passbands on measured total-ozone accuracy is determined using a numerical model of the spectral measurement process. The model enables the calculation of corrections for the 'bandwidth-effect' error and shows that highly attenuating passband skirts and well-suppressed leakage bands are at least as important as narrow half-bandwidths. Over typical ranges of airmass and total ozone, the range in the bandwidth-effect correction is about 2% in total ozone for the filter instrument, compared with about 1% for the Dobson instrument.

Basher, R. E.↗
NASA NTRS1977

A numerical analysis for a comparative study of the pointing accuracy of flexible satellites

The analytical models for flexible satellites have been reported earlier. Numerical results comparing the pointing accuracy of three-axes stabilized, spinning, and dual-spin satellites are presented here. The responses are compared for deterministic and random models with and without external torques. The performances of a uniform control system have been compared to a time-optimal control system for the same base-line configurations.

Huang, T. C.↗
NASA NTRS1978

Modifications to the accuracy assessment analysis routine SPATL to produce an output file

The SPATL is an analysis program in the Accuracy Assessment Software System which makes comparisons between ground truth information and dot labeling for an individual segment. In order to facilitate the aggregation cf this information, SPATL was modified to produce a disk output file containing the necessary information about each segment.

Carnes, J. G.↗
NASA NTRS1977

On achieving sufficient dual station range accuracy for deep space navigation at zero declination

Since the Voyager Mission will encounter Saturn at a time when the planet will be nearly in the earth's equatorial plane, earth-based orbit determination will be more difficult than usual because of the so-called zero-declination singularity associated with conventional radiometric observations. Simulation studies show that in order to meet the required delivery accuracy at Saturn, a relative range measurement between the Goldstone and Canberra Deep Space Stations must be accurate to 4.5 times the square root of two meters. Topics discussed include the nature of error sources, the methodology and technology required for calibration, the verification process concerning the nearly simultaneous range capability, a description of the ranging system, and tracking strategy.

Siegel, H. L.↗
NASA NTRS1978

Effects of accumulated film layers on the accuracy of quartz film thickness monitors

The effect of accumulation layers on the accuracy of quartz thin-film thickness monitors is evaluated. Use of an expanded plane wave ultrasonic propagation theory correctly accounts for observed experimental data. The magnitude of the maximum errors calculated for simply reversing the order of a series of aluminum gold deposits is on the order of 5%. If one totally neglects intervening layers, multiple film propagation and nonlinearity can produce errors greater than 50%.

Heyman, J. S.↗
NASA NTRS1978

Accuracy analysis of pointing control system of solar power station

The first-phase effort concentrated on defining the minimum basic functions that the retrodirective array must perform, identifying circuits that are capable of satisfying the basic functions, and looking at some of the error sources in the system and how they affect accuracy. The initial effort also examined three methods for generating torques for mechanical antenna control, performed a rough analysis of the flexible body characteristics of the solar collector, and defined a control system configuration for mechanical pointing control of the array.

Hung, J. C.↗
NASA NTRS1978

Large Area Crop Inventory Experiment (LACIE). LACIE third interim phase 3 accuracy assessment report

The author has identified the following significant results. An accuracy of 90/85 was achieved with the October estimates which had a relative bias of -9.9 percent and a coefficient of variation of 5.2 percent for the total wheat production in the USGP. The probability was 0.9 that the LACIE estimate was within + or - 15 percent of true wheat production for the USGP. The LACIE spring wheat production underestimates in August, September, and October were the results of area underestimates for spring wheat in the USNGP region. The winter wheat blind study showed that the average proportion estimates were significantly different from the average dot-count, ground truth proportions at the USSGP and USGP-7 levels.

Source record↗
NASA NTRS1979

Accuracy aspects of stereo side-looking radar

The geometry of the radar stereo model and factors affecting visual radar stereo perception are reviewed. Limits to the vertical exaggeration factor of stereo radar are defined. Radar stereo model accuracies are analyzed with respect to coordinate errors caused by errors of radar sensor position and of range, and with respect to errors of coordinate differences, i.e., cross-track distances and height differences.

Leberl, F. W.↗
NASA NTRS1977

An accuracy analysis of the LDAR system

An accuracy report of the Lightning Detection and Ranging System is presented. The effect of quantizing errors are modelled by use of a computer. The errors in the four configurations of the LDAR System are compared to the limiting errors in an ideal hyperbolic system. Performance data from the track of a jet plane and for the indicated position of a fixed lightning simulator are analyzed for dispersions in the data. Error models show the quality and the areas of highly accurate data, and show how the data deteriorates outside the primary measuring range.

Poehler, H. A.↗
NASA NTRS1978

Accuracy of vertical deflection determination by present-day inertial instrumentation

An analysis of results obtained in the Canadian Rock Mountains indicates that the observation of deflection differences along the same line can be repeated with a precision of about 0.5 sec but that there are systematic discrepancies between the forward and the backward running of the same line. A comparison with the available astronomically determined deflections also shows systematic differences of 2 sec and 3 sec. These errors are most likely due to the overshooting of the Kalman procedure at gradient changes. It appears that the software can be altered in such a way that deflection differences between stations, not more than half an hour of travel time apart, can be determined by the inertial system with an accuracy of better than + or - 1 sec.

Schwarz, K. P.↗