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  • Other Sources  (124)
  • 2010-2014  (74)
  • 1975-1979  (49)
  • 1940-1944  (1)
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  • 1
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    Happy Canyon - A new type of enstatite achondrite (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Mineralogical and chemical characteristics of the Happy Canyon meteorite, found in 1971 near Wayside, Texas, show it to be a new type of enstatite achondrite occupying the gap between the recrystallized enstatite chondrites and the igneous, crystalline, unbrecciated enstatite chondrites. Although the bulk composition of the specimen is consistent with that of an E6 enstatite chondrite, it has a crystal cumulate texture. There are minor amounts of metal and troilite which have survived extensive weathering. The Happy Canyon meteorite may represent an E6 composition which has melted and reprecipitated at a slightly higher oxidation state, possibly in the core of a small parent body.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Meteoritics; 12; June 30
    Format: text
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  • 2
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    Visible GaAs/0.7/P/0.3/ CW heterojunction lasers (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The paper reports the first low-threshold red-light-emitting heterojunction laser diodes consisting of lattice-matched Ga(As,P)/(In,Ga)P heteroepitaxial layers. A room-temperature threshold current of 3400 A/sq cm was obtained at a wavelength of about 7000 A; this value is substantially lower than those achieved at this wavelength with (Al,Ga)As lasers. For the first time, continuous-wave laser operation at temperatures as high as 10 C has been obtained for GaAs(1-x)P(x).
    Keywords: LASERS AND MASERS
    Type: Applied Physics Letters; 30; Mar. 1
    Format: text
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  • 3
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    Red-emitting Ga/As,P///In,Ga/P heterojunction lasers (1978)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The paper describes in detail the properties of vapor-grown double-heterojunction lasers of Ga(As,P)/(In,Ga)P with room-temperature threshold current densities as low as 3400 A/sq cm at 7000 A and 6600 A/sq cm at 6800 A. These thresholds are three to eight times smaller than those of (Al,Ga)As lasers in this wavelength range due to the shorter-wavelength direct-indirect transition in Ga(As,P). The optical and electrical characteristics of the Ga(As,P)/(In,Ga)P lasers are found to be similar to those of (Al,Ga)As, with fundamental transverse-mode operation to 70 C, and spontaneous carrier lifetimes between 5 and 8 nsec typically observed at low current densities.
    Keywords: LASERS AND MASERS
    Type: Journal of Applied Physics; 49; June 197
    Format: text
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  • 4
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    Electrical conductivity measurements from the STRATCOM 8 experiment (1978)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: A blunt probe experiment for measuring electrical conductivity was flown with the STRATCOM 8 instrument package. Data were obtained by the instrument throughout the entire measurement period. A preliminary analysis of the data indicates an enhancement in conductivity associated with the krypton discharge ionization lamp, particularly in negative conductivity. The conductivity values and their altitude dependence are consistent with previous balloon and rocket results.
    Keywords: GEOPHYSICS
    Type: NASA. Goddard Space Flight Center STRATCOM 8 Data Workshop and Suppl.; p 96-102
    Format: text
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  • 5
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    Measurement of D-region electron density by partial reflections (1978)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Measurements of electron density in the lower ionosphere were made at White Sands Missile Range throughout the STRATCOM VIII launch day using a partial-reflection sounder. Information regarding the sounder's antenna pattern was gained from the passage of the balloon over the array.
    Keywords: GEOPHYSICS
    Type: NASA. Goddard Space Flight Center STRATCOM 8 Data Workshop and Suppl.; p 91-95
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  • 6
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    Optimization of multi-element airfoils for maximum lift (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Two theoretical methods are presented for optimizing multi-element airfoils to obtain maximum lift. The analyses assume that the shapes of the various high lift elements are fixed. The objective of the design procedures is then to determine the optimum location and/or deflection of the leading and trailing edge devices. The first analysis determines the optimum horizontal and vertical location and the deflection of a leading edge slat. The structure of the flow field is calculated by iteratively coupling potential flow and boundary layer analysis. This design procedure does not require that flow separation effects be modeled. The second analysis determines the slat and flap deflection required to maximize the lift of a three element airfoil. This approach requires that the effects of flow separation from one or more of the airfoil elements be taken into account. The theoretical results are in good agreement with results of a wind tunnel test used to corroborate the predicted optimum slat and flap positions.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Res. Center Advanced Technol. Airfoil Res., Vol. 1, Pt.1; p 237-253
    Format: application/pdf
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  • 7
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    Saturn's microwave spectrum: Implications for the atmosphere and the rings (1978)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Measurements of Saturn's disk temperature are compiled to determine the planet's microwave spectrum from 1 mm to 100 cm wavelength. The data were adjusted to conform with a common flux density scale. A model of Saturn's rings is used to remove the effects of the rings from the atmospheric component at centimeter and decimeter wavelengths. Theoretical spectra for a number of convective atmospheric models were computed and compared with the observed spectrum. Radiative-convective models with approximately solar composition and with an effective temperature of approximately 89 K are in good agreement with the observations. The agreement between the observed and theoretical spectra is a strong indication that gaseous ammonia is present in Saturn's atmosphere. A good fit to the data is obtained with an ammonia mixing ratio of approximately 5 x 10,0001. A comparison of the millimeter wavelength data with the best-fitting atmospheric spectrum indicates that the thermal component of the ring brightness temperature near 1 mm wavelength is approximately 25 k.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Its The Saturn System; p 195-216
    Format: application/pdf
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  • 8
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    Transient excitation and data processing techniques employing the fast fourier transform for aeroelastic testing (1976)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The development of testing techniques useful in airplane ground resonance testing, wind tunnel aeroelastic model testing, and airplane flight flutter testing is presented. Included is the consideration of impulsive excitation, steady-state sinusoidal excitation, and random and pseudorandom excitation. Reasons for the selection of fast sine sweeps for transient excitation are given. The use of the fast fourier transform dynamic analyzer (HP-5451B) is presented, together with a curve fitting data process in the Laplace domain to experimentally evaluate values of generalized mass, model frequencies, dampings, and mode shapes. The effects of poor signal to noise ratios due to turbulence creating data variance are discussed. Data manipulation techniques used to overcome variance problems are also included. The experience is described that was gained by using these techniques since the early stages of the SST program. Data measured during 747 flight flutter tests, and SST, YC-14, and 727 empennage flutter model tests are included.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Langley Res. Center Flutter Testing Tech.,; p 77-114
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  • 9
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    Interannual Variability of Ozone in the Winter Lower Stratosphere and the Relationship to Lamina and Irreversible Transport (2010)
    In:  Other Sources
    Details
    Publication Date: 2018-06-06
    Description: We use the high-resolution dynamic limb sounder (HIRDLS) high-vertical resolution ozone profiles in the northern hemisphere lower stratosphere to examine the meridional transport out of the tropics. We focus on February 2005.2007 when there are differences in the dynamical background in the lower stratosphere due to the states of the quasibiennial oscillation and polar vortex. HIRDLS data reveal a large number of low ozone laminae that have the characteristics of tropical air at midlatitudes. More laminae are observed in February in 2006 than in 2005 or 2007. Because laminae can form, move out of the tropics, and return to the tropics without mixing into the midlatitude ozone field, the number of laminae is not directly related to the net transport. We use equivalent latitude coordinates to discriminate between reversible and irreversible laminar transport. The equivalent latitude analysis shows greater irreversible transport between the tropics and lower midlatitudes in both 2005 and 2007 compared to 2006 despite the higher number of laminae observed in 2006. Our conclusion that there was more irreversible transport of tropical air into the lower midlatitudes in 2005 and 2007 is supported by equivalent length analysis of mixing using microwave limb sounder N2O measurements. This study shows that reversibility must be considered in order to infer the importance of lamination to net transport.
    Keywords: Meteorology and Climatology
    Type: Journal of Geophysical Research (ISSN 0148-0227); Volume 115; D15305
    Format: text
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  • 10
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    Identification of Knock in NACA High-Speed Photographs of Combustion in a Spark-Ignition Engine (1943)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Report presents the results of a study of combustion in a spark-ignition engine given in NACA Technical Reports 704 and 727. The present investigation was made with the NACA high-speed motion-picture camera, operating at 40,000 photographs a second, and with a cathode-ray oscillograph operating on a piezoelectric pick-up in the combustion chamber. Photographs are presented showing that the origin of knock is not necessarily in the end gas. The data obtained indicates that knock takes place only in a part of the cylinder charge which has been previously ignited either by autoignition or by the passage of the flame fronts but which has not burned to completion. Mottled regions in the high-speed Schlieren photographs are demonstrated to represent combustion regions.
    Type: NACA-TR-761
    Format: application/pdf
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