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  • 1
    Publication Date: 2019-01-25
    Description: Magnetite-wuestite spherules collected from deep-sea sediments are thought to have originally been Fe-Ni metal particles at the top of the atmosphere that were oxidized and melted during entry into the earth's atmosphere. Some likely sources for the metal particles are Fe-Ni interplanetary dust particles (IDP's) and metal or sulfide from stony IDP's that separated after melting. Davis et al. reported that four of these spherules are enriched in the heavy isotopes of iron, with enrichments of 8-23%/amu. We have developed a technique for analysis of both iron and nickel isotopes on the same ion microprobe spot and have applied this technique to a number of deep-sea spherules in order to better understand the processes leading to isotopic mass fractionation. Eight spherules show iron and nickel isotopic mass fractionation, with iron and nickel enriched in the heavy isotopes by 10-19%/amu and 4-32%/amu, respectively. If the mass fractionations are due to Rayleigh fractionation during evaporation, these spherules lost 76-94% of their original mass. We have analyzed the four magnetite-wuestite spherules for which iron isotopic data were reported by Davis et al. as well as four new spherules.
    Keywords: GEOPHYSICS
    Type: Lunar and Planetary Inst., Twenty-fourth Lunar and Planetary Science Conference. Part 1: A-F; p 373-374
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  • 2
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    In:  Other Sources
    Publication Date: 2019-01-25
    Description: Orthicon television auroral films indicating more motion and internal structure than is apparent by direct viewing
    Keywords: GEOPHYSICS
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  • 3
    Publication Date: 2013-08-31
    Description: The reduction and publication of an extensive data set collected in experiments over several years at Ames and PSI is briefly examined. Hartmann has been assembling data sets from his experiments on catastrophic fragmentation of various materials, including basalt, other igneous rock, ice, and weak dirt clods. Weidenschilling and Davis have continued to gather and reduce data on oblique impacts. The data indicate a power law distribution of ejecta mass vs. velocity, with a slope that is independent of azimuth, and does not vary with impact angle from normal impacts to at least 75 deg from vertical. In order to improve models of coagulation of dust aggregates in the solar nebula, SJW developed an apparatus for drop tests of fragile projectiles. Davis and Weidenschilling continued to collect and analyze experimental data on collisional catastrophic disruption at the Ames Vertical Gun Range.
    Keywords: GEOPHYSICS
    Type: NASA, Washington, Reports of Planetary Geology and Geophysics Program, 1986; p 388-390
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  • 4
    Publication Date: 2013-08-31
    Description: The TP-LIF OH sensor is based on the principle that a molecule having multiple energy states, all of which are bonding, can be pumped into the highest state with the resulting fluorescence being blue-shifted relative to all pumping wavelengths. In this way, one can successfully discriminate against virtually all noise sources in the system using long wavelength blocking filters in conjunction with solar-blind photomultiplier tubes. Thus, these systems tend to be signal limited rather than signal-to-noise limited as is true of the SP-LIF technique as well as other conventional analytical methods. The trick to achieving the above sampling scheme, with high efficiency, is in the use of high photon fluxes of short time duration. Obviously, the latter type of light source is fulfilled nicely by available pulsed lasers. From an operational point of view, however, this laser source needs to be tunable. The latter characteristic permits extremely high selectivity for the detection of a diatomic or simple polyatomic molecule by taking advantage of the high-resolution spectroscopic features of these type species.
    Keywords: GEOPHYSICS
    Type: NASA. Langley Research Center Future Directions for H sub x O sub y Detection; p 37-38
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  • 5
    Publication Date: 2013-08-31
    Description: Several local edge detection operators were applied to a set of ERTS pictures of the Monterey, Calif. area. Gradient operators performed consistently better than laplacian operators in detecting edges. It was also found that if a grayscale normalization operation, histogram flattening, was applied to the pictures first, the edge detector outputs were greatly enhanced. The use of interpolation for more accurate location of edges on a digital picture was also briefly investigated. Curve detection operators were applied to the edge detector outputs; this had the effect of enhancing the edges while suppressing noise.
    Keywords: GEOPHYSICS
    Type: NASA-CR-138963 , TR-312
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  • 6
    Publication Date: 2016-03-07
    Description: The author has identified the following significant results. During preliminary analysis of the ERTS-1 RBV band-2 images it was possible to detect many geologic features and to delineate several geologic formation boundaries. Also, the spatial frequency characteristics of some different geologic formations are distinguishable from each other. At the present time there is not enough data to provide any statistical evaluation of these differences, but it is hoped that more quantitative results will be produced within the next few months. Multispectral analysis will begin when the retrospective order for the other spectral bands of the first images is received. Since many geologic formation boundaries are visible on the single band that has been analyzed so far, even greater visibility is expected with the spectral information available in the additional bands.
    Keywords: GEOPHYSICS
    Type: NASA-CR-128176 , E72-10122
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  • 7
    Publication Date: 2013-08-31
    Description: Rocket borne rubidium magnetometer measurements for latitude determination of equatorial electrojet
    Keywords: GEOPHYSICS
    Type: NASA-TM-X-55787 , X-612-66-334
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  • 8
    Publication Date: 2013-08-31
    Description: Auroral electrojet activity index and universal time variations
    Keywords: GEOPHYSICS
    Type: X-612-65-264 , NASA-TM-X-55310
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  • 9
    Publication Date: 2013-08-31
    Description: Increased understanding of the chemical phenomena occurring in the troposphere was the research goal. Emphasis was placed on tropospheric impact on environmental quality, including public health, agriculture, climate, and weather.
    Keywords: GEOPHYSICS
    Type: L-13855 , NASA-RP-1062
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  • 10
    Publication Date: 2013-08-31
    Description: A reliable payload system and scaled down shaped charges were developed for carrying out experiments in solar-terrestrial magnetospheric physics. Four Nike-Tomahawk flights with apogees near 450 km were conducted to investigate magnetospheric electric fields, and two Taurus-Tomahawk rockets were flown in experiments on the auroral acceleration process in discrete auroras. In addition, a radial shaped charge was designed for plasma perturbation experiments.
    Keywords: GEOPHYSICS
    Type: NASA-CR-162581
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