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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 415 records · Page 23
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

Statistical energy analysis response prediction methods for structural systems

The results of an effort to document methods for accomplishing response predictions for commonly encountered aerospace structural configurations is presented. Application of these methods to specified aerospace structure to provide sample analyses is included. An applications manual, with the structural analyses appended as example problems is given. Comparisons of the response predictions with measured data are provided for three of the example problems.

Davis, R. F.↗
NASA NTRS1981

Applications of non-parametric statistics and analysis of variance on sample variances

Nonparametric methods that are available for NASA-type applications are discussed. An attempt will be made here to survey what can be used, to attempt recommendations as to when each would be applicable, and to compare the methods, when possible, with the usual normal-theory procedures that are avavilable for the Gaussion analog. It is important here to point out the hypotheses that are being tested, the assumptions that are being made, and limitations of the nonparametric procedures. The appropriateness of doing analysis of variance on sample variances are also discussed and studied. This procedure is followed in several NASA simulation projects. On the surface this would appear to be reasonably sound procedure. However, difficulties involved center around the normality problem and the basic homogeneous variance assumption that is mase in usual analysis of variance problems. These difficulties discussed and guidelines given for using the methods.

Myers, R. H.↗
NASA NTRS1992

An analysis of radio pulsar nulling statistics

Survival analysis methods are used to seek correlations between the fraction of null pulsars and other pulsar characteristics for an ensemble of 72 radio pulsars. The strongest correlation is found between the null fraction and the pulse period, suggesting that nulling is a manifestation of a faltering emission mechanism. Correlations are also found between the fraction of null pulses and other parameters that have a strong dependence on the pulse period. The results presented here suggest that nulling is broad-band and may ultimately be explained in terms of polar cap models of pulsar emission.

Biggs, James D.↗
NASA NTRS1977

Analysis of voltage data

The use of statistical analysis (regression analysis) to determine the data correlation between eight voltage parameters is discussed. The eight parameters correlated include: temperature, depth of discharge; charge rate; discharge rate; percent recharge; concentration of KOH; amount of KOH; and precharge. Graphs are presented which show: (1) starpoint/centerpoint cycles to failure vs. parameters; (2) cycles to failure vs. temperature; and (3) positive and negative plate thickness and weight vs. cycles. An empirical equation derived from cycles to failure vs. temperature graph for cells cycled at 1C charge, 2C discharge, and 14 percent recharge is also presented.

Mcdermott, P. P.↗
NASA NTRS1984

Vector wind gust model

The development of a vector wind gust model through statistical analysis is described. Wind perturbation statistics which include location, altitude, season, and wavelength range are used in the synthesis of detailed wing profiles. These profiles provide the basis for the establishment of improved discrete gust design criteria guidelines for ascending launch vehicles.

Adelfang, S. I.↗
NASA NTRS1985

Synopsis of the Fifth Conference on the Meteorology of the Stratosphere and Mesosphere

The papers presented at the Fifth Conference on the Meteorology of the Stratosphere and Mesosphere held on April 23-26, 1985, are reviewed. The observational aspects of large-scale circulation, such as summer and winter circulation in the Southern Hemisphere, and analysis schemes, like the multivariate statistical analysis scheme, are discussed. The topics of numerical simulations of the general circulation and sudden-warming are examined. Papers concerning processes of O3, NO2, H2, and HNO3 are described. Research on large-scale mixing processes in the stratosphere is presented. The topic of equatorial dynamics and stability is analyzed. Papers focusing on the effect of gravity waves on the general circulation are studied.

Schoeberl, M. R.↗
NASA NTRS1988

Initial blood storage experiment

The design of the Initial Blood Storage Experiment (IBSE) was based upon a carefully controlled comparison between identical sets of human blood cell suspensions - red cells, white cell, and platelets - one set of which was transported aboard the Columbia on a 6 day 11 hour mission, and the other held on the ground. Both sets were carried inside stainless steel dewars within specially fabricated flight hardware. Individual bags of cell suspensions were randomly assigned with respect to ground vs orbit status, dewar chamber, and specific location within the dewar. To foster optimal preservation, each cell type was held under specific optimal conditions of pH, ionic strength, solute concentration, gas tension, and temperature. An added variable in this initial experiment was provided by the use of three different polymer/plasticizer formulations for the sealed bags which held the blood cells. At termination of the experiment, aliquots of the suspensions, identified only by code, were distributed to be assayed. Assays were selected to constitute a broad survey of cellular properties and thereby maximize the chances of detection of gravitational effects. A total of 74 different outcome measurements were reported for statistical analysis. When the measurements were completed, the results were entered into the IBSE data base, at which time the data were matched with the original blood bag numbers to determine their status with respect to polymer/plasticizer type, orbit status (orbit or ground), and storage position within the experimental hardware. The data were studied by analysis of variance. Initially, type of bag and orbital status were main factors; later more detailed analyses were made on specific issues such as position in the hardware and specific plastic. If the analysis of variance indicated a statistical significance at the 5 percent level the corresponding p-value was reported.

Surgenor, Douglas MACN.↗