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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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Probabilistic Hazard Assessment for Tornadoes, Straight-Line Wind, and Extreme Precipitation at the Savannah River Site

Recent data sets for three meteorological phenomena with the potential to inflict damage on SRS facilities – tornadoes, straight-line winds, and heavy precipitation – are analyzed using appropriate statistical techniques to estimate the occurrence probabilities for these events in the future. Summaries of the results for DOE-mandated return periods and comparisons to similar calculations performed in 2013 by Werth et al. (W2013) are given. Using tornado statistics for i) the combined states of Georgia and South Carolina, and ii) a 2⁰ square area surrounding SRS, we calculated the probability per year of any location at SRS being struck by a tornado (the ‘strike’ probability) and the probability that any point will experience winds above set thresholds. The strike probability was calculated to be 7.04E-4 (1 chance in 1420) per year and tornadic wind speeds for DOE mandated return periods of 50,000 years (corresponding to wind design category 3 (WDC-3), and 125,000 years (meeting WDC-4) (USDOE, 2016) were estimated to be 132 mph and 147 mph, respectively. By contrast, default tornado wind speeds taken from ANSI/ANS-2.3-2011 are somewhat higher: 161 mph for return periods of 50,000 years and 173 mph every 125,000 years (ANS, 2011). Although the ANS and the SRS evaluation used the same basic model (Ramsdell and Rishel, 2007), the region defined in ANS 2.3 that encompasses the SRS also includes areas of the Great Plains and lower Midwest, regions with much higher occurrence frequencies of strong tornadoes. The SRS straight-line wind values associated with various return periods were calculated by fitting existing wind data to a GEV1 distribution and extrapolating the values for any return period from the tail of that function. For the DOE mandated return periods, we expect straight-line winds of 117 mph every 2500 years (the required WDC-3 standard) and 125 mph every 6250 years (WDC-4) at any point within the SRS. These values are similar to those from the ANS-2.3-2011 report, which has wind speeds of 125mph and 133 mph for return periods of 2500 years and 6250 years, respectively. For extreme precipitation, we compared the fits of two different theoretical extreme-value distributions and applied the one that fit the data best for each of several accumulation periods. The DOE mandated 6-hr accumulated rainfall for return periods of 10,000 years (corresponding to precipitation design category 3 (PDC-3) and 25,000 years (PDC-4) were estimated as 9.1 inches and 10.1 inches, respectively. For the 24-hr rainfall return periods of 10,000 years and 25,000 years, total rainfall estimates were 12.02 inches and 13.17 inches, respectively, higher than comparable values provided in the W2013 report.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1969

Long range holographic contour mapping concept

Plan for generating a two dimensional contour map of a distant object with range contour intervals of a few millimeters to a few inches is accomplished by using a laser light source which has a periodically varying coherence function to form a hologram of the object.

Brooks, R. E.↗
NASA NTRS1971

Graphite minority carriers.

It is demonstrated that there are (at least) two sets of minority carriers in graphite, which are essentially the same for both natural single crystals and for pyrolytic samples. Both materials have similar minority carrier de Haas-van Alphen periods as a function of the angle between the C axis and the magnetic field.

Woollam, J. A.↗
NASA NTRS1974

Jupiter's clouds - Equatorial plumes and other cloud forms in the Pioneer 10 images

The imaging photopolarimeter experiment aboard the Pioneer 10 spacecraft produced two-dimensional maps of intensity and polarization in red and blue light at high resolution during flyby of Jupiter in December 1973. The present article describes cloud forms seen in the equatorial zone and compares them with rotational periods as a function of latitude derived from earth-based observations of features on Jupiter. A striking new feature consists of a bright, well-defined nucleus in the equatorial zone, with a plume apparently drawn out from the core of the nucleus.

Fountain, J. W.↗
NASA NTRS1976

Predicted lightcurves of Phobos and Deimos

Using Mariner 9 results on the shapes, rotation periods, and photometric functions of Phobos and Deimos, approximate orbital light curves are calculated for the two Martian satellites. The prediction is that both Phobos and Deimos should show orbital brightness fluctuations detectable from earth. For Phobos, the detectable amplitude is predicted to be about 0.1 mag; for Deimos, 0.2 mag.

Noland, M.↗
NASA NTRS1979

Maximum likelihood estimation for life distributions with competing failure modes

Systems which are placed on test at time zero, function for a period and die at some random time were studied. Failure may be due to one of several causes or modes. The parameters of the life distribution may depend upon the levels of various stress variables the item is subject to. Maximum likelihood estimation methods are discussed. Specific methods are reported for the smallest extreme-value distributions of life. Monte-Carlo results indicate the methods to be promising. Under appropriate conditions, the location parameters are nearly unbiased, the scale parameter is slight biased, and the asymptotic covariances are rapidly approached.

Sidik, S. M.↗
NASA NTRS1979

Cooling tower water conditioning study

Successful elimination of cooling tower treatment chemicals was demonstrated. Three towers functioned for long periods of time with ozone as the only treatment for the water. The water in the systems was reused as much as 30 times (cycles of concentration) without deleterious effects to the heat exchangers. Actual system blow-down was eliminated and the only makeup water added was that required to replace the evaporation and mist entrainment losses. Minimum water savings alone are approximately 75.1 1/kg/year. Cost estimates indicate that a savings of 55 percent was obtained on the systems using ozone. A major problem experienced in the use of ozone for cooling tower applications was the difficulty of accurate concentration measurements. The ability to control the operational characteristics relies on easily and accurately determined concentration levels. Present methods of detection are subject to inaccuracies because of interfering materials and the rapid destruction of the ozone.

Humphrey, M. F.↗
NASA NTRS1982

Sunspot variation and selected associated phenomena: A look at solar cycle 21 and beyond

Solar sunspot cycles 8 through 21 are reviewed. Mean time intervals are calculated for maximum to maximum, minimum to minimum, minimum to maximum, and maximum to minimum phases for cycles 8 through 20 and 8 through 21. Simple cosine functions with a period of 132 years are compared to, and found to be representative of, the variation of smoothed sunspot numbers at solar maximum and minimum. A comparison of cycles 20 and 21 is given, leading to a projection for activity levels during the Spacelab 2 era (tentatively, November 1984). A prediction is made for cycle 22. Major flares are observed to peak several months subsequent to the solar maximum during cycle 21 and to be at minimum level several months after the solar minimum. Additional remarks are given for flares, gradual rise and fall radio events and 2800 MHz radio emission. Certain solar activity parameters, especially as they relate to the near term Spacelab 2 time frame are estimated.

Wilson, R. M.↗
NASA NTRS1984

Pulse Response Yields Battery Charge State

Response to input pulse characterizes state of charge of battery. Instrument electronically measures input and response of forcing-function pulse that periodically modulates charge or discharge current.

Chapman, C. P.↗
NASA NTRS1983

Ultrastructure of meristem and root cap of pea seedlings under spaceflight conditions

Data of electron microscopic analysis of meristem and root cap of pea seedlings grown aboard the Salyut-6 orbital research station in the Oazis apparatus and in the laboratory are presented. The main morphological and anatomical characteristics of the test and control plants are shown to be similar. At the same time, some differences are found in the structural and functional organization of the experimental cells as compared to the controls. They concern first of all the plastic apparatus, mitochondria and Golgi apparatus. It is assumed that cell function for certain periods of weightlessness on the whole ensures execution of the cytodifferentiation programs genetically determined on the Earth. Biochemical and physiological processes vary rather markedly due to lack of initially rigorous determination.

Sytnyk, K. M.↗
NASA NTRS1983

Halogen Occultation Experiment (HALOE) gas cell life test program

The Halogen Occultation Experiment (HALOE) will use gas filter correlation radiometry to measure the atmospheric concentration profiles of HCl, HF, NO, and CH4 from the Upper Atmosphere Research Satellite. The need to contain the gases for the gas filter measurements has resulted in the development of gas cells and the need for a life test program to demonstrate that the gas cells will perform their functions for extended periods (several years) of time. This report describes the tests in the life test program, the test apparatus used, and the analysis techniques developed. The report also presents data obtained during the first 14 months of the test program.

Sullivan, E. M.↗
NASA NTRS1984

Photometry of CPD - 48 deg 1577

U, B, and V photometry is presented for CPD - 48 deg 1577, the newly discovered cataclysmic variable with the greatest known apparent brightness. The light curves are dominated by flickering but do suggest an orbital period of nearly 4 hr. Power spectra of 5 nights of U-band observations failed to reveal the presence of any periodic or quasi-periodic oscillations. Autocorrelation functions suggest that two time-scales exist in the flickering activity, one of 77 s and the other 500 s. The implications for a shot noise model of flickering are discussed.

Williams, G. A.↗
NASA NTRS1990

Gamma radiation from radio pulsars

The probable magnetospheric location and source of the gamma ray emission from some young radiopulsars is discussed. The suggested evolution of this emission as a function of pulsar period gives a diminished gamma-ray luminosity for a more rapidly spinning pre-Crab pulsar. A greatly enhanced one, similar to that of unidentified Cos B sources, is predicted for a slightly slower post-Vela pulsar, followed by a relatively rapid quenching of the gamma-ray luminosity at still longer periods. Possible anomalous exo-magnetospheric pulsed MeV and TeV-PeV radiation from the Crab pulsar is considered.

Ruderman, Malvin↗
NASA NTRS1991

Multimission observations of 4U 1538 - 52

Archival data from the eclipsing binary X-ray pulsar 4U 1538 - 52 have been analyzed. These data were obtained from four different X-ray missions and span a baseline of 12 yr. Scanning observations were made using the Uhuru satellite during May 9-15, 1972 and using HEAO A1 during August 26-31, 1977 and February 22-28, 1978. Pointed observations were made using the Einstein Observatory during March 2, 1979 and Exosat during March 17, August 7-8 and 10-11, 1984. These data are used to improve the orbital period determination, to set a limit to the change in orbital period, and to improve the knowledge of the pulse period as a function of time. Exosat pulse profiles are presented and pulse-phase spectroscopy is performed. The pulsation observations of 4U 1538 - 52 are modeled geometrically, and parameters for magnetic beaming of the accretion column are derived.

Cominsky, L. R.↗
NASA NTRS1991

Cataclysmic variable evolution - Clues from the underlying white dwarf

This paper presents an update of determinations of the CV white dwarf effective-temperature, T(eff), together with an initial exploration of the possible implications and constraints on the CV lifetimes and evolution based on the ensemble of white dwarf T(eff) values as a function of orbital period. The CV dwarf luminosities are derived by using the T(eff) data and adopting the masses of individual CV white dwarfs determined by Webbink (1990). The present ensemble of empirically determined white dwarf effective temperatures reveals a distribution centered near 16,000 K, implying a mean lower limit total cooling lifetime of 5 x 10 to the 8th yr for the majority of CV degenerates. The two coolest CV degenerates, VV Puppis and St LMi, were found among the strongly magnetic AM Her CVs.

Sion, Edward M.↗
NASA NTRS1991

Polarimetric passive remote sensing of periodic surfaces

The concept of polarimetry in active remote sensing is extended to passive remote sensing. The potential use of the third and fourth Stokes parameters U and V, which play an important role in polarimetric active remote sensing, is demonstrated for passive remote sensing. It is shown that, by the use of the reciprocity principle, the polarimetric parameters of passive remote sensing can be obtained through the solution of the associated direct scattering problem. These ideas are applied to study polarimetric passive remote sensing of periodic surfaces. The solution of the direct scattering problem is obtained by an integral equation formulation which involves evaluation of periodic Green's functions and normal derivative of those on the surface. Rapid evaluation of the slowly convergent series associated with these functions is observed to be critical for the feasibility of the method. New formulas, which are rapidly convergent, are derived for the calculation of these series. The study has shown that the brightness temperature of the Stokes parameter U can be significant in passive remote sensing. Values as high as 50 K are observed for certain configurations.

Veysoglu, Murat E.↗