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Results for “Principal Component”

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 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Design and performance evaluation of a cryogenic condenser for an in-pile experiment

An apparatus was designed to enable in-pile irradiation of materials in liquid hydrogen at cryogenic temperatures. One of the principal components of this apparatus was a horizontal tube condenser. The performance of the condenser was evaluated by running a liquid-nitrogen prototype of the apparatus at heat loads comparable to or greater than those expected during the irradiation. The test showed that the condenser was capable of handling the design heat load and that the design procedure was sound.

Graham, R. W.↗
NASA NTRS1971

A predictive model of human performance.

An attempt is made to develop a model describing the overall responses of humans to exercise and environmental stresses for prediction of exhaustion vs an individual's physical characteristics. The principal components of the model are a steady state description of circulation and a dynamic description of thermal regulation. The circulatory portion of the system accepts changes in work load and oxygen pressure, while the thermal portion is influenced by external factors of ambient temperature, humidity and air movement, affecting skin blood flow. The operation of the model is discussed and its structural details are given.

Walters, R. F.↗
NASA NTRS1973

A unified development of several techniques for the representation of random vectors and data sets

Linear vector space theory is used to develop a general representation of a set of data vectors or random vectors by linear combinations of orthonormal vectors such that the mean squared error of the representation is minimized. The orthonormal vectors are shown to be the eigenvectors of an operator. The general representation is applied to several specific problems involving the use of the Karhunen-Loeve expansion, principal component analysis, and empirical orthogonal functions; and the common properties of these representations are developed.

Bundick, W. T.↗
NASA NTRS1973

Design of a nuclear isotope heat source assembly for a spaceborne mini-Brayton power module.

Results of a study to develop a feasible design definition of a heat source assembly (HSA) for use in nominal 500-, 1200-, or 2000-W(e) mini-Brayton spacecraft power systems. The HSA is a modular design which is used either as a single unit to provide thermal energy to the 500-W(e) mini-Brayton power module or in parallel with one or two additional HSAs for the 1200- or 2000-W(e) power module systems. Principal components consist of a multihundred watt RTG isotope heat source, a heat source heat exchanger which transfers the thermal energy from the heat source to the mini-Brayton power conversion system, an auxiliary cooling system which provides requisite cooling during nonoperation of the power conversion module and an emergency cooling system which precludes accidental release of isotope fuel in the event of system failure.

Wein, D.↗
NASA NTRS1974

Design study for a magnetically supported reaction wheel

Results are described of a study program in which the characteristics of a magnetically supported reaction wheel are defined. Tradeoff analyses are presented for the principal components, which are then combined in several reaction wheel design concepts. A preliminary layout of the preferred configuration is presented along with calculated design and performance parameters. Recommendations are made for a prototype development program.

Stocking, G.↗
NASA NTRS1974

Multispectral combination and display of ERTS-1 data

Standard NASA color composites combine the most relevant 3 bands from the 4 MSS bands available. An alternate approach is to extract the principal components of the data by a linear transformation of the 4 bands. This approach leads to a low dimensionality representation of ERTS-1 data with the least degradation, in the mean square sense, of the radiometric accuracy. The technique has been applied with success to ERTS-1 MSS data for several geographic areas in California. For all examples considered the mean square representation error is less than one percent. By combining this dimensionality reduction which our previous results on image enhancement for visual display, color composites are obtained which contain and display most of the information provided by the ERTS-1 sensors.

Algazi, V. R.↗
NASA NTRS1974

A statistical-chemical and thermodynamic approach to the study of lunar mineralogy

Principal components analysis is used to study the chemical compositions of pyroxenes of five Apollo 12 specimens. Important correlations are recognized in the variation of oxide weight per cent. These correlations indicating substitutional relationships can be interpreted as representative of stable and metastable trends of crystallization by using crystal-chemical and thermodynamic information. The per cent variance of pyroxene groups with characteristic trends in each specimen can be evaluated and interpreted in terms of history of crystallization. Distribution of Fe and Mg in certain pairs of olivine and pyroxene, which are found in contact in the rock and which may have crystallized simultaneously, is useful in recognizing the tendency towards chemical equilibrium in Fe-Mg distribution during a limited interval in the liquidus or subsolidus stages.

Saxena, S. K.↗
NASA NTRS1974

Multivariate analyses of crater parameters and the classification of craters

Multivariate analyses were performed on certain linear dimensions of six genetic types of craters. A total of 320 craters, consisting of laboratory fluidization craters, craters formed by chemical and nuclear explosives, terrestrial maars and other volcanic craters, and terrestrial meteorite impact craters, authenticated and probable, were analyzed in the first data set in terms of their mean rim crest diameter, mean interior relief, rim height, and mean exterior rim width. The second data set contained an additional 91 terrestrial craters of which 19 were of experimental percussive impact and 28 of volcanic collapse origin, and which was analyzed in terms of mean rim crest diameter, mean interior relief, and rim height. Principal component analyses were performed on the six genetic types of craters. Ninety per cent of the variation in the variables can be accounted for by two components. Ninety-nine per cent of the variation in the craters formed by chemical and nuclear explosives is explained by the first component alone.

Siegal, B. S.↗
NASA NTRS1974

Leasing of federal geothermal resources

Pursuant to the Geothermal Steam Act of 1970 and the regulations published on December 21, 1973, the first Federal geothermal competitive lease sale was held on January 22, 1974, by the Department of the Interior, offering 33 tracts totalling over 50,000 acres in three Known Geothermal Resource Areas in California. On January 1, 1974, Federal lands outside Known Geothermal Resource Areas were opened to noncompetitive lease applications, of which, 3,763 had been received by June 1, 1974. During fiscal year 1974, a total of 22 competitive leases had been issued in California and Oregon. The principal components in the Department involved in the leasing program are the Geological Survey and the Bureau of Land Management. The former has jurisdiction over drilling and production operations and other activities in the immediate area of operations. The latter receives applications and issues leases and is responsible for managing leased lands under its jurisdiction outside the area of operations. The interrelationships of the above agencies and the procedures in the leasing program are discussed.

Stone, R. T.↗
NASA NTRS1975

Comparison of some biased estimation methods (including ordinary subset regression) in the linear model

Ridge, Marquardt's generalized inverse, shrunken, and principal components estimators are discussed in terms of the objectives of point estimation of parameters, estimation of the predictive regression function, and hypothesis testing. It is found that as the normal equations approach singularity, more consideration must be given to estimable functions of the parameters as opposed to estimation of the full parameter vector; that biased estimators all introduce constraints on the parameter space; that adoption of mean squared error as a criterion of goodness should be independent of the degree of singularity; and that ordinary least-squares subset regression is the best overall method.

Sidik, S. M.↗
NASA NTRS1975

The LANDSAT-1 multispectral scanner as a tool in the classification of inland lakes

Relationships between LANDSAT-1 multispectral scanner (MSS) data and the trophic status of a group of lakes in the north-northeastern part of the United States were studied by predicting the magnitudes of two trophic state indicators, estimating lake position on a multivariate trophic scale, and automatically classifying lakes according to their trophic state. Initially, the principal component ordination was employed with 100 lakes. MSS data for some 20 lakes was then extracted from computer-compatible tapes (CCT) using a binary marking technique. The output was in the form of descriptive statistics and photographic concatenations. Color ratios were incorporated into regression models for the prediction of Secchi disc transparency, chlorophyll a, and lake position on the tropic scale. Results indicate that the LANDSAT-1 system, although handicapped by low spectral and spatial resolutions as well as excessive cloud cover, can be used as a supplemental data source in lake survey programs.

Boland, D. H. P.↗
NASA NTRS1977

Statistical evaluation of control inputs and eye movements in the use of instruments clusters during aircraft landing

Two different types of analyses were done on data from a study in which eye movements and other variables were recorded while four pilots executed landing sequences in a Boeing 737 simulation. Various conditions were manupulated, including changes in turbulence, starting position, and instrumentation. Control inputs were analyzed in the context of the various conditions and compared against ratings of workload obtained using the Cooper-Harper scale. A number of eye-scanning measures including mean dwell time and transition from one instrument to another were entered into a principal components factor analysis. The results show a differentiation between control inputs and eye-scanning behavior. This shows the need for improved definition of workload and experiments to uncover the important differences among control inputs, eye-scanning and cognitive processes of the pilot.

Dick, A. O.↗
NASA NTRS1977

Lunar heat-flow experiment

The principal components of the experiment were probes, each with twelve thermometers of exceptional accuracy and stability, that recorded temperature variations at the surface and in the regolith down to 2.5 m. The Apollo 15 experiment and the Apollo 17 probes recorded lunar surface and subsurface temperatures. These data provided a unique and valuable history of the interaction of solar energy with lunar surface and the effects of heat flowing from the deep interior out through the surface of the moon. The interpretation of these data resulted in a clearer definition of the thermal and mechanical properties of the upper two meters of lunar regolith, direct measurements of the gradient in mean temperature due to heat flow from the interior and a determination of the heat flow at the Apollo 15 and Apollo 17 sites.

Langseth, M. G.↗
NASA NTRS1978

Evaluation of LANDSAT MSS vs TM simulated data for distinguishing hydrothermal alteration

The LANDSAT Follow-On (LFO) data was simulated to demonstrate the mineral exploration capability of this system for segregating different types of hydrothermal alteration and to compare this capability with that of the existing LANDSAT system. Multispectral data were acquired for several test sites with the Bendix 24-channel MSDS scanner. Contrast enhancements, band ratioing, and principal component transformations were used to process the simulated LFO data for analysis. For Red Mountain, Arizona, the LFO data allowed identification of silicified areas, not identifiable with LANDSAT 1 and 2 data. The improved LFO resolution allowed detection of small silicic outcrops and of a narrow silicified dike. For Cuprite - Ralston, Nevada, the LFO spectral bands allowed discrimination of argillic and opalized altered areas; these could not be spectrally discriminated using LANDSAT 1 and 2 data. Addition of data from the 1.3- and 2.2- micrometer regions allowed better discriminations of hydrothermal alteration types.

Abrams, M. J.↗
NASA NTRS1977

VLBI (Very Long Baseline Interferometry) instrumental effects, part 1

Very Long Baseline Interferometry (VLBI) is a method for observation of extragalactic radio sources which appears to have potential for precise long-distance earth surveying, clock synchronization and spacecraft navigation. Many researchers have been working to establish the accuracy of VLBI observations. The intent of the work reported here is to review the principal components of the VLBI instrument in order to estimate and/or bound the systematic error contributions. In this first of a series of articles, the definitions and tools which are needed in order to apply filter transfer-function analysis to the VLBI receiver are established and they are used to estimate the sensitivity of the VLBI receiver to plausible filter variations.

Layland, J. W.↗
NASA NTRS1978

Discrimination of rock classes and alteration products in southwestern Saudi Arabia with computer-enhanced LANDSAT data

Digital LANDSAT MSS data for an area in the southwestern Arabian Shield were computer-enhanced to improve discrimination of rock classes, and recognition of gossans associated with massive sulphide deposits. The test area is underlain by metamorphic rocks that are locally intruded by granites; these are partly overlain by sandstones. The test area further includes the Wadi Wassat and Wadi Qatan massive sulphide deposits, which are commonly capped by gossans of ferric oxides, silica, and carbonates. Color patterns and boundaries on contrast-stretched ratio color composite imagery, and on complementary images constructed using principal component and canonical analyses transformations, correspond exceptionally well to 1:100,000 scale field maps. A qualitative visual comparison of information content showed that the ratio enhancement provided the best overall image for identification of rock type and alteration products.

Blodget, H. W.↗
NASA NTRS1978

The effect of NaCl/g/ on the oxidation of NiAl

NaCl is ingested into operating gas turbines. The effect of this salt on the high temperature surface stability properties of turbine hardware is not well understood. The involvement of gaseous NaCl in the high temperature oxidation of NiAl, a principal component in many high temperature environmental coatings, is herein examined. The results of this work indicate that gaseous NaCl present in an oxidizing atmosphere affects the formation of Al2O3 whiskers on a dense Al2O3 layer. Such whisker growth, attributed to vapor transport processes through an otherwise dense Al2O3 scale, increases the aluminum depletion of the NiAl substrate.

Smeggil, J. G.↗
NASA NTRS1979

NASA Facts. An Educational Publication of the National Aeronautics and Space Administration: Space Shuttle

The versatility of space shuttle, its heat shieldings, principal components, and facilities for various operations are described as well as the accomodations for the spacecrew and experiments. The capabilities of an improved space suit and a personal rescue enclosure containing life support and communication systems are highlighted. A typical mission is described.

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