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  • 1
    facet.materialart.
    Unbekannt
    In:  Bull. Seism. Soc. Am., San Francisco, Pergamon, vol. 66, no. 5496, pp. 639-666, pp. B05315, (ISSN: 1340-4202)
    Publikationsdatum: 1976
    Schlagwort(e): SModelling ; Source mechanics ; Source ; BSSA
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
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    Unbekannt
    In:  Bull. Seism. Soc. Am., San Francisco, Pergamon, vol. 66, no. 6, pp. 1821-1846, pp. 1246
    Publikationsdatum: 1976
    Schlagwort(e): Earth tides ; TIDES ; Inhomogeneity ; BSSA
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
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    Unbekannt
    In:  Bull. Seism. Soc. Am., Tulsa, 3-4, vol. 66, no. 3-4, pp. 173-187, pp. B09405, (ISBN: 0-12-018847-3)
    Publikationsdatum: 1976
    Schlagwort(e): Seismology ; Location ; AUD ; Hypocenter determination ; BSSA
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
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    Unbekannt
    In:  Bull. Seism. Soc. Am., Roma, Polish Geothermal Association, vol. 66, no. 2, pp. 1459-1484, pp. B05406, (ISSN: 1340-4202)
    Publikationsdatum: 1976
    Schlagwort(e): High frequency ... ; Data analysis / ~ processing ; Fault plane solution, focal mechanism ; Seismology ; BSSA
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
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    Unbekannt
    In:  Bulletin of the Seismological Society of America, Tokyo, Am. Geophys. Union, vol. 66, no. 6, pp. 2069-2074, pp. 8043
    Publikationsdatum: 1976
    Schlagwort(e): Earthquake precursor: prediction research ; ethics ; Seismology ; society ; BSSA
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
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    Unbekannt
    In:  Bull. Seism. Soc. Am., Hannover, Bundesanstalt für Geowissenschaften und Rohstoffe, vol. 66, no. 40, pp. 1441-1457, pp. L08305
    Publikationsdatum: 1976
    Schlagwort(e): Nuclear explosion ; Stress ; P-waves ; Seismology ; BSSA
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
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    Unbekannt
    In:  Bull. Seism. Soc. Am., London, Geological Society, vol. 66, no. 3, pp. 843-868, pp. L24307, (ISBN 1-86239-117-3)
    Publikationsdatum: 1976
    Schlagwort(e): Seismicity ; Turkey ; BSSA
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
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    Unbekannt
    In:  Bull. Seism. Soc. Am., Amsterdam, Academic Press (Elsevier), vol. 66, no. 4, pp. 1293-1321, pp. 2486, (ISBN 1-86239-117-3)
    Publikationsdatum: 1976
    Schlagwort(e): Site amplification ; Spectrum ; method ; noksp ; BSSA
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
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    Unbekannt
    In:  Bull. Seism. Soc. Am., Heidelberg, 1, vol. 66, no. 4-5, pp. 667-675, pp. B01401, (ISBN: 0534351875, 2nd edition)
    Publikationsdatum: 1976
    Schlagwort(e): Crustal deformation (cf. Earthquake precursor: deformation or strain) ; Elasticity ; BSSA
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
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    Unbekannt
    In:  Bull. Seism. Soc. Am., Regensburg, Inst. Electrical & Electronics Engineers, vol. 66, no. 3, pp. 1501-1523, pp. TC5001, (ISBN: 0534351875, 2nd edition)
    Publikationsdatum: 1976
    Schlagwort(e): Source parameters ; Magnitude ; Source ; BSSA
    Standort Signatur Erwartet Verfügbarkeit
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  • 11
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    Unbekannt
    In:  Bull. Seism. Soc. Am., Regensburg, Inst. Electrical & Electronics Engineers, vol. 66, no. 3, pp. 1801-1804, pp. TC5001, (ISBN: 0534351875, 2nd edition)
    Publikationsdatum: 1976
    Schlagwort(e): Body waves ; Stress drop ; Elasticity ; Seismology ; BSSA
    Standort Signatur Erwartet Verfügbarkeit
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  • 12
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    Unbekannt
    In:  Bull. Seism. Soc. Am., Warszawa, Elsevier, vol. 66, no. 1, pp. 617-623, pp. 2091, (ISBN: 0-12-018847-3)
    Publikationsdatum: 1976
    Schlagwort(e): Seismology ; BSSA
    Standort Signatur Erwartet Verfügbarkeit
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  • 13
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    Unbekannt
    In:  Bull. Seism. Soc. Am., Hannover, FU Berlin, vol. 66, no. 3, pp. 1485-1499, pp. 5091692, (ISBN: 0-12-018847-3)
    Publikationsdatum: 1976
    Schlagwort(e): Inversion ; Body waves ; Earthquake ; Source ; Source parameters ; BSSA
    Standort Signatur Erwartet Verfügbarkeit
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  • 14
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    Unbekannt
    In:  Bull. Seism. Soc. Am., Houston, Akademie-Verlag, vol. 66, no. 6, pp. 1953-1964, pp. L08310, (ISSN: 1340-4202)
    Publikationsdatum: 1976
    Schlagwort(e): Seismology ; Teleseismic events ; Seismic arrays ; Schafer ; BSSA
    Standort Signatur Erwartet Verfügbarkeit
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  • 15
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    Unbekannt
    In:  Bull. Seism. Soc. Am., New York, Scientific American, vol. 66, no. Nov., pp. 979-985, pp. B10302, (ISSN: 1340-4202)
    Publikationsdatum: 1976
    Schlagwort(e): Seismology ; Instruments ; Detectors ; BSSA
    Standort Signatur Erwartet Verfügbarkeit
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  • 16
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    Unbekannt
    In:  Bull. Seism. Soc. Am., Warszawa, EGS, vol. 66, no. 4, pp. 1343-1373, pp. 1089, (ISSN: 1340-4202)
    Publikationsdatum: 1976
    Schlagwort(e): Site amplification ; Earthquake engineering, engineering seismology ; Spectrum ; Strong motions ; Magnitude ; Attenuation ; Modelling ; noksp ; BSSA
    Standort Signatur Erwartet Verfügbarkeit
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  • 17
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    Unbekannt
    In:  Bull. Seism. Soc. Am., Hannover, Elsevier, vol. 66, no. 4, pp. 1375-1380, pp. L15S14, (ISSN: 1340-4202)
    Publikationsdatum: 1976
    Schlagwort(e): Detectors ; Data analysis / ~ processing ; ARRAY ; Seismic networks ; BSSA
    Standort Signatur Erwartet Verfügbarkeit
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  • 18
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    Unbekannt
    In:  Bull. Seism. Soc. Am., Corvallis, x + 406 pp., Oregon State University Press, vol. 66, no. 1, pp. 1881-1885, pp. L13610, (ISSN: 1340-4202)
    Publikationsdatum: 1976
    Schlagwort(e): EDV ; Energy (of earthquakes) ; Amplitude ; Data analysis / ~ processing ; Reflectivity ; BSSA
    Standort Signatur Erwartet Verfügbarkeit
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  • 19
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    Unbekannt
    In:  CASI
    Publikationsdatum: 2006-08-09
    Beschreibung: An idealized two-dimensional example of rapid interface flow extension is described. Initially undisturbed dissimilar isotropic, homogeneous, linearly elastic half-spaces are perfectly bonded along the interface y=0. Quantities associated with the half-space or = to 0 are denoted by the prime superscript or the subscripts 3 or 4 while those in y or = to 0 carry the subscripts 1 or 2. At time t=0 adjacent material points at x=0, y= + or - 0 are forced apart horizontally with a constant relative velocity delta v. This results in a zone of bond failure which extends symmetrically along the interface at a constant rate c. The newly created flaw surfaces are in sliding contact resisted by Coulomb friction. The friction coefficient is gamma.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Langley Res. Center Advan. in Eng. Sci., Vol. 1; p 239-246
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  • 20
    Publikationsdatum: 2006-08-09
    Beschreibung: Based on the two dimensional theory of elasticity and by the use of Muskhelishvili's technique, the influence of a circular hole, under uniform normal pressure, on the stresses around a line crack in an infinite plate subjected to tension is discussed. Numerical calculations were carried out, and the variation of the crack tip stress intensity factor due to the geometry was clarified.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Langley Res. Center Advan. in Eng. Sci., Vol. 1; p 275-282
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  • 21
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    In:  CASI
    Publikationsdatum: 2006-01-12
    Beschreibung: Working primarily from the recent SAS-2 observations of galactic gamma rays, the relation of these observations to the large scale distribution of cosmic rays and interstellar gas in the galaxy is reviewed and reexamined. Starting with a discussion of production rates, the case for pion decay being the predominant production mechanism in the galactic disk above 100 MeV is reestablished and it is also pointed out that Compton gamma rays can be a significant source. To facilitate discussion, the concepts of four distinct galactic regions are defined, viz. the nebulodisk, ectodisk, radiodisk and exodisk. Bremsstrahlung and pion decay gamma rays are associated with the first two (primarily the first) regions, and Compton gamma rays and synchrotron radiation are associated with the latter two regions. On a large scale, the cosmic rays, interstellar gas (primarily H2 clouds in the inner galaxy) and gamma ray emissivity all peak in a region between 5 and 6 kpc from the galactic center. This correlation is related to correlation with other population I phenomena and is discussed in terms of the density wave concept of galactic structure. The singular nature of the HI distribution appears to follow the supernova remnant and pulsar distributions in the galaxy.
    Schlagwort(e): SPACE RADIATION
    Materialart: The Struct. and Content of the Galaxy and Galactic Gamma Rays; p 357-391
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  • 22
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    In:  CASI
    Publikationsdatum: 2006-01-12
    Beschreibung: The distribution of nonthermal emissivity with height z above the galactic plane is examined. The main result is that recent observations of the distribution of brightness at intermediate latitudes in the galaxy and of the edge-on spiral galaxy NGC 891 indicate that the emissivity extends to heights of several kpc perpendicular to the plane. The relationship between the nonthermal emissivity and the neutral gas is also studied. In several galaxies the angular distributions of neutral hydrogen and nonthermal emission are roughly coextensive and show similar features such as spiral structure. If radio galaxies and normal galaxies with strong nuclear radio sources are excluded, there appears to be a proportionality between their total HI content and their nonthermal radio luminosity.
    Schlagwort(e): SPACE RADIATION
    Materialart: NASA. Goddard Space Flight Center The Struct. and Content of the Galaxy and Galactic Gamma Rays; p 206-221
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  • 23
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    In:  CASI
    Publikationsdatum: 2006-01-12
    Beschreibung: The detection of gamma rays from supernovae will provide interesting tests of current theory. Some current ideas on the expected gamma ray flux, as modified by recent theoretical results are reviewed.
    Schlagwort(e): SPACE RADIATION
    Materialart: NASA. Goddard Space Flight Center The Struct. and Content of the Galaxy and Galactic Gamma Rays; p 289-298
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  • 24
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    In:  CASI
    Publikationsdatum: 2006-01-12
    Beschreibung: In October 1975 the high energy gamma ray flux from the Vela pulsar was measured by COS-B to be 1.6 to 2.1 times higher than the flux measured by SAS-2 in 1973. The existence is confirmed of a second region of enhanced radiation in the galactic anticenter in addition to that from the Crab pulsar.
    Schlagwort(e): SPACE RADIATION
    Materialart: NASA. Goddard Space Flight Center The Struct. and Content of the Galaxy and Galactic Gamma Rays; p 45A-51
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  • 25
    Publikationsdatum: 2006-01-12
    Beschreibung: Continuing analysis of the data from the SAS-2 high energy gamma-ray experiment has produced an improved picture of the sky at photon energies above 35 MeV. On a large scale, the diffuse emission from the galactic plane is the dominant feature observed by SAS-2. This galactic plane emission is most intense between galactic longitude 310 and 45 deg, corresponding to a region within 7kpc of the galactic center. Within the high-intensity region, SAS-2 observes peaks around galactic longitudes 315 deg, 330 deg, 345 deg, 0 deg, and 35 deg. These peaks appear to be correlated with such galactic features and components as molecular hydrogen, atomic hydrogen, magnetic fields, cosmic ray concentrations, and photon fields.
    Schlagwort(e): SPACE RADIATION
    Materialart: The Struct. and Content of the Galaxy and Galactic Gamma Rays; p 1-11C
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  • 26
    Publikationsdatum: 2006-01-12
    Beschreibung: A grazing incidence telescope sensitive to radiation in the 5- to 100-nanometer band was flown in the Apollo service module. On 10 nighttime revolutions, the command and service module was maneuvered to point the instrument at 30 different stellar targets for periods of 1 to 20 minutes, thus constituting the first sensitive search for extreme ultraviolet radiation from nonsolar sources. Several hours of supplementary data were also obtained during nighttime orbits when other experiments in the scientific instrument module bay were operating. Preliminary analysis of a small fraction of the total data indicates the definite detection of a strong source of extreme ultraviolet radiation during observations made during revolution 109. The source is located in Coma Berencies. The suggested optical identification is the white dwarf HZ 43. If this association is correct, the star has the highest temperature of any known white dwarf. Regardless of the optical identification, however, this object is the first nonsolar source to be detected in the extreme ultraviolet band.
    Schlagwort(e): SPACE RADIATION
    Materialart: NASA. Lyndon B. Johnson Space Center Apollo-Soyuz Test Project; 16 p
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  • 27
    Publikationsdatum: 2006-01-12
    Beschreibung: The GSFC Cosmic X-ray Spectroscopy experiment aboard OSO-8 has operated successfully since launch providing spectral and temporal data on X-ray sources in tha energy range 2-60 keV. Analysis of quick look data shows a variety of spectral features, some stable, others variable, which will increase understanding of the nature of individual sources. In particular, observed emission and absorption features that can be attributed to iron will result in abundance measures of this important element in sources such as some X-ray binaries, the supernova remnant Cas A, and the nucleus of the galaxy Cen A.
    Schlagwort(e): SPACE RADIATION
    Materialart: X-ray Binaries; p 67-79
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  • 28
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    In:  CASI
    Publikationsdatum: 2006-01-12
    Beschreibung: The cosmic rays, an active gaseous component of the disk of the galaxy, are considered along with their propagation and containment as a part of the general dynamics of the disk. The sources of cosmic rays are a matter of speculation. The disk is inflated by the cosmic ray gas pressure comparable to the magnetic pressure, but the rate of inflation is unknown. The time spent by the individual cosmic ray particles in the disk is inversely proportional to the cosmic ray production rate. It is evident from the decay of Be(1c) that the cosmic rays circulate through a volume of space perhaps ten times the thickness of the gaseous disk, suggesting a magnetic halo extending out approximately 1 kpc from either face of the disk. The cosmic rays may be responsible for the halo by inflating the magnetic fields of the disk. Extension of the fields to 1 kpc would imply a high production rate and short life of cosmic rays in the dense gaseous disk of the galaxy.
    Schlagwort(e): SPACE RADIATION
    Materialart: NASA. Goddard Space Flight Center The Struct. and Content of the Galaxy and Galactic Gamma Rays; p 320-340
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  • 29
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    In:  CASI
    Publikationsdatum: 2006-01-12
    Beschreibung: Observation of 0.2-100 MeV diffuse gamma radiation emitted from the Galaxy can provide information on the intensities of 5-50 MeV/nucleon cosmic-rays and 50 MeV electrons in interstellar space. Recent measurements of gamma-rays emitted from the galactic center region provide evidence for a diffuse continuum between 10 and 100 MeV. The intensities of the recently reported nuclear line gamma rays, also observed in the direction of the galactic center, require the presence of intense fluxes of low-energy cosmic-rays in the inner Galaxy if the gamma-rays are produced on a galactic scale. Current detection techniques for 0.1-100 MeV gamma-ray measurements are summarized and their capabilities for measuring the diffuse galactic emission are evaluated.
    Schlagwort(e): SPACE RADIATION
    Materialart: NASA. Goddard Space Flight Center. The Struct. and Content of the Galaxy and Galactic Gamma Rays; p 65-83
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  • 30
    Publikationsdatum: 2006-01-12
    Beschreibung: The crystal activation experiment consisted of two sample packages that were flown in the command module and returned to earth for analysis of the radioactivity induced in them during the flight. The objective of the experiment was to define the background caused by detector activation that interferes when gamma radiation is measured in the 0.02- to 10-megaelectronvolt range from earth orbit. Preliminary results show that the activation of the NaI(Tl) crystal was a factor of 3 below that from a similar measurement on Apollo 17. The identification of certain species and the level of activation observed show an important contribution from the interactions of thermal and energetic neutrons produced as secondaries in the spacecraft. That the activation was reduced by only a factor of 3 compared with the Apollo 17 experiment, despite the geomagnetically shielded orbit, possibly indicates more efficient secondary neutron production by the more energetic cosmic rays.
    Schlagwort(e): SPACE RADIATION
    Materialart: Apollo-Soyuz Test Project; 10 p
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  • 31
    Publikationsdatum: 2006-01-12
    Beschreibung: Many theoretical models were developed in an attempt to explain the spatial structure in the observed emission which results from interactions of energetic cosmic rays with the interstellar gas. The peaks in the observed distribution are remarkably well correlated with longitudes corresponding to tangential directions to known spiral arm features. Based on theoretical and experimental arguments, it is assumed that on the scale of galactic arms the cosmic rays are more intense where the mass of the gas to which they are coupled is greatest. Refining this model with the results of recent surveys of the interstellar gas, a good fit to the observations is obtained whether the cosmic rays are confined to the spiral arms in the disk or are more evenly confined as in a flat halo model.
    Schlagwort(e): SPACE RADIATION
    Materialart: The Struct. and Content of the Galaxy and Galactic Gamma Rays; p 341-354
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  • 32
    Publikationsdatum: 2006-01-12
    Beschreibung: High resolution data on the pulsed gamma ray emission from the Crab and Vela pulsars are presented. The light curves of these two pulsars at gamma ray energies show striking similarities.
    Schlagwort(e): SPACE RADIATION
    Materialart: NASA. Goddard Space Flight Center The Struct. and Content of the Galaxy and Galactic Gamma Rays; p 52-64
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  • 33
    Publikationsdatum: 2006-01-12
    Beschreibung: The COS-B satellite carries a single experiment, capable of detecting gamma rays with energies greater than 30 MeV. Its objectives are to study the spatial, energy, and time characteristics of high energy radiation of galactic and extragalactic origin. The capability to search for gamma ray pulsations is enhanced by the inclusion in the payload of a proportional counter sensitive to X-rays of 2-12 Kev. The experiment was calibrated using particle accelerators. The results of these measurements are presented and the performance of the system in orbit is discussed.
    Schlagwort(e): SPACE RADIATION
    Materialart: NASA. Goddard Space Flight Center The Struct. and Content of the Galaxy and Galactic Gamma Rays; p 23-38
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  • 34
    Publikationsdatum: 2006-01-12
    Beschreibung: The Apollo Soyuz Test Project Soft X-ray Experiment was designed to observe celestial X-ray sources in the energy range from 0.1 to 10 kiloelectronvolts. The instrument that was used in the experiment obtained energy and fast timing data to characterize both the spectrum and the variability of known X-ray sources. Data were obtained on approximately 12 sources. During the mission, the instrument developed an intermittent high voltage discharge problem that resulted in the loss of approximately 75 percent of the anticipated data, including the scans intended for mapping of the low energy diffuse X-ray background.
    Schlagwort(e): SPACE RADIATION
    Materialart: NASA. Lyndon B. Johnson Space Center Apollo-Soyuz Test Project; 11 p
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  • 35
    Publikationsdatum: 2006-01-12
    Beschreibung: Gamma-ray emission was detected from the radio pulsars PSR1818-04 and PSR1747-46, in addition to the previously reported gamma-ray emission from the Crab and Vela pulsars. Since the Crab pulsar is the only one observed in the optical and X-ray bands, these gamma-ray observations suggest a uniquely gamma-ray phenomenon occurring in a fraction of the radio pulsars. Using distance estimates it is found that PSR1818-04 has a gamma-ray luminosity comparable to that of the Crab pulsar, while the luminosities of PSR1747-46 and the Vela pulsar are approximately an order of magnitude lower. This survey of SAS-2 data for pulsar correlations has also yielded upper limits to gamma-ray luminosity for 71 other radio pulsars.
    Schlagwort(e): SPACE RADIATION
    Materialart: The Struct. and Content of the Galaxy and Galactic Gamma Rays; p 12-22
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  • 36
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    In:  CASI
    Publikationsdatum: 2006-01-12
    Beschreibung: During the first months of operation, COS-B has observed galactic high energy gamma rays from the galactic disc. In the galactic center and Vela regions the disc emission distribution was measured. From these data the existence of a local ( 1 kpc) and a distant ( 3 kpc) emitting region is apparent in the general direction of the inner galaxy.
    Schlagwort(e): SPACE RADIATION
    Materialart: NASA. Goddard Space Flight Center The Galaxy and Galactic Gamma Rays; p 39-44
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  • 37
    Publikationsdatum: 2006-01-12
    Beschreibung: The Apollo Soyuz Test Project Interstellar Helium Glow Experiment (MA-088) studied the motion of helium in the local interstellar medium as that medium passed through the solar system to determine several poorly known properties of the local interstellar gas. The instrument used was a photometer sensitive to two solar extreme ultraviolet spectral lines that are resonantly scattered by helium gas. The instrument surveyed the entire celestial sphere during a series of slow, rolling maneuvers by the Apollo spacecraft. The equipment operated properly, and usable data were obtained.
    Schlagwort(e): SPACE RADIATION
    Materialart: NASA. Lyndon B. Johnson Space Center Apollo-Soyuz Test Project; 15 p
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  • 38
    Publikationsdatum: 2006-08-09
    Beschreibung: The effect of subcritical crack growth on the geometry dependence of nonlinear fracture toughness parameters was studied by comparing the toughness values for different specimen geometries at the onset of subcritical crack growth and at the initiation of unstable crack propagation. Center-cracked thin sheet specimens of 2024-T3 and 7075-T6 aluminum alloys were tested by varying the specimen length L, width w, and crack length-to-width ratio c/w. When the onset of unstable crack propagation was selected as the critical point, the nonlinear energy toughness and the R curve toughness increased with increasing w and decreasing L and c/w. However, when the onset of subcritical crack growth was taken as the critical point, energy toughness and the linear toughness values were independent of these geometrical variables.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Langley Res. Center Advan. in Eng. Sci., Vol. 1; p 257-266
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  • 39
    Publikationsdatum: 2006-08-09
    Beschreibung: The problem to be considered is the sudden appearance of a flaw or crack in a strip of material of finite height subjected to tensile loading. Stress waves are generated within the strip and are reflected from boundary to boundary. Of interest is the maximum value of the dynamic stress intensity factor at a given instance of time as the strip height to crack length ratio is varied.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Langley Res. Center Advan. in Eng. Sci., Vol. 1; p 205-214
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  • 40
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    In:  Other Sources
    Publikationsdatum: 2011-08-17
    Beschreibung: An exact three-dimensional analysis of wave propagation in laminated orthotropic circular cylindrical-shells is developed. Numerical results are presented for three-ply shells, and for various axial wave lengths, circumferential wave numbers, and thicknesses. Results from a thin shell theory and a refined approximate theory are compared with the exact results.
    Schlagwort(e): STRUCTURAL MECHANICS
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  • 41
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    In:  Other Sources
    Publikationsdatum: 2011-08-17
    Beschreibung: Jupiter's decimetric emission is universally identified as synchrotron radiation from about 10 MeV electrons. These electrons radiate away their energy in a few months and hence must be continuously replaced. A theory in which electrons are injected at Jupiter's magnetopause and radially diffuse toward the planetary surface, gaining energy in the process is summarized. The radial diffusion coefficient in the inner magnetosphere is determined. This diffusion coefficient, which also holds for protons, is sufficiently small that the inner Galilean satellites can wipe out large fractions of the incoming proton and electron fluxes. The reduction of the proton flux is extremely important to the survival of the Pioneer experimental payloads.
    Schlagwort(e): SPACE RADIATION
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  • 42
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    Publikationsdatum: 2011-08-17
    Beschreibung: Thin-gaged or high toughness materials containing cracks usually fail in a ductile manner with nominal failure stresses approaching the ultimate strength of the material. For such materials, a two-parameter fracture criterion was developed. An equation which related the linear elastic stress-intensity factor, elastic nominal stress, and two material parameters has previously been derived and has been used as a fracture criterion for surface- and through-cracked specimens under tensile loading. In the present paper the two-parameter fracture criterion was rederived in a more general form and was extended to compact and notch-bend fracture specimens. A close correlation was found between experimental and calculated failure stresses.
    Schlagwort(e): STRUCTURAL MECHANICS
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  • 43
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    Publikationsdatum: 2011-08-17
    Beschreibung: By use of the principle of superposition the stiff-flanged shear web is modeled mathematically by an infinite elastic strip with fixed longitudinal edges. The shear-stress intensity factor for a central longitudinal crack is calculated for various values of the ratio of strip width to crack length, h/a, in the range 0.1-10. The interaction of the crack with the boundaries is illustrated by boundary shear-stress distributions for three values of h/a. Some implications of the results for the design of damage-tolerant shear webs are discussed briefly.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: International Journal of Fracture; 12; Apr. 197
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  • 44
    Publikationsdatum: 2011-08-17
    Beschreibung: A candidate hodoscope uses arrays of scintillator fibers, followed by an image intensifier and imaging system such as that proposed for the X-ray shadowgraph. A literature search was performed to ascertain the experience of other workers with hodoscopes using this or similar principles. Calculations were performed to determine the feasibility of candidate systems and some laboratory experiments were performed to attempt to check these numbers.
    Schlagwort(e): SPACE RADIATION
    Materialart: The Specific Light Output of Cesium Iodide Crystals; p 45-58
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  • 45
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    Publikationsdatum: 2011-08-17
    Beschreibung: An analytic model is developed to calculate the reliability of a structure after it is inspected for cracks. The model accounts for the growth of undiscovered cracks between inspections and their effect upon the reliability after subsequent inspections. The model is based upon a differential form of Bayes' Theorem for reliability, and upon fracture mechanics for crack growth.
    Schlagwort(e): STRUCTURAL MECHANICS
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  • 46
    Publikationsdatum: 2011-08-17
    Beschreibung: The fully-stressed design (FSD) appears to be the most widely used approach for sizing of flight structures under strength and minimum-gage constraints. Almost all of the experience with FSD has been with structures primarily under mechanical loading as opposed to thermal loading. In this method the structural sizes are iterated with the step size, depending on the ratio of the total stress to the allowable stress. In this paper, the thermal fully-stressed design (TFSD) procedure developed for problems involving substantial thermal stress is extended to biaxial stress members using a Von Mises failure criterion. The TFSD resizing procedure for uniaxial stress is restated and the new procedure for biaxial stress members is developed. Results are presented for an application of the two procedures to size a simplified wing structure.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: AIAA Journal; 14; Oct. 197
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  • 47
    Publikationsdatum: 2011-08-16
    Beschreibung: A study of the gas-to-dust ratio suggests that interstellar reddening may provide an accurate way of assessing column densities in various directions in the Galaxy. A gamma ray intensity of 7.25 x 10 to the -5th E sub B-V photon/sq cm/s/sterad is predicted for regions of the Galaxy where the medium cosmic ray density is equal to that observed close to the sun. It is found that in the longitude range of about 0-180 degrees, the large scale cosmic ray distribution producing the gamma rays follows that of extreme population I stars put in evidence by giant H II regions, and that of molecular hydrogen traced by carbon monoxide emission. The gamma-ray production exhibits a maximum at R roughly equal to 5 kpc, and practically vanishes at R not less than 11 kpc, beyond the location of the outermost H II regions.
    Schlagwort(e): SPACE RADIATION
    Materialart: Astronomy and Astrophysics; 50; 2, Ju; July 197
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  • 48
    Publikationsdatum: 2011-08-17
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: Journal of Sound and Vibration; 49; Dec. 8
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  • 49
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    Publikationsdatum: 2011-08-17
    Beschreibung: The paper considers the consistency of positrons and electrons with a propagation model in which the cosmic rays are stopped by nuclear collisions or energy losses before they can escape from the Galaxy (the closed-galaxy model). The fact that no inconsistency is found between the predictions and the data implies that the protons which produce the positrons by nuclear reactions could have their origin in a large number of distant sources, as opposed to the heavier nuclei which in this model come from a more limited set of sources. The closed-galaxy model predicts steep electron and positron spectra at high energies. None of these are inconsistent with present measurements; but future measurements of the spectrum of high-energy positrons could provide a definite test for the model. The closed-galaxy model also predicts that the interstellar electron intensity below a few GeV is larger than that implied by other models. The consequence of this result is that electron bremsstrahlung is responsible for about 50% of the galactic gamma-ray emission at photon energies greater than 100 MeV
    Schlagwort(e): SPACE RADIATION
    Materialart: Astrophysics and Space Science; 45; Nov. 197
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  • 50
    facet.materialart.
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    Publikationsdatum: 2011-08-17
    Beschreibung: High resolution measurement of the iron group nuclei was performed with the intention of determining individual abundances in the cosmic ray flux at the earth of particles with z = 22 to 30. Of the three types of dE/dx detectors used in the experiment, pulse ion chambers, Cerenkov radiators and scintillators, the first has the best z resolution over a wide range of particle z and energy. The plastic scintillators define the particle acceptance cone of the telescope while the Cerenkov detector aids in rejection of low energy particle background and measurement of particle velocity.
    Schlagwort(e): SPACE RADIATION
    Materialart: The Specific Light Output of Cesium Iodide Crystals; p 1-44
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  • 51
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    Publikationsdatum: 2011-08-16
    Beschreibung: The intensity and energy spectrum of primary cosmic electrons from 10 to about 250 GeV have been studied by using balloon-borne detectors. The detectors were large-area ionization calorimeters which sampled showering particles frequently and demonstrated an energy resolution of about 7% in calibration tests. On one of the flights a time-of-flight system and detectors to sample the lateral properties of showers were used to examine and to test background rejection. The results of the balloon flights from Alamogordo, N. Mex., in 1970 and Cape Girardeau, Mo., in 1972 indicated that the primary cosmic ray electron differential energy spectrum exhibits no change of slope in the energy range measured and is well represented by a power law. The results indicate that the cosmic electron spectrum is steeper than the cosmic ray proton spectrum. It is shown that these data are consistent with the leakage lifetime model for the propagation of cosmic electrons in the galaxy, although other more complex models cannot be excluded on the basis of these data.
    Schlagwort(e): SPACE RADIATION
    Materialart: Journal of Geophysical Research; 81; Aug. 1
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  • 52
    Publikationsdatum: 2011-08-16
    Beschreibung: The current theory of solar modulation can be used to argue that the cosmic-ray component at low energies, which is observed to have an anomalous composition, is not of galactic origin, i.e., it is not a component of the galactic cosmic-ray flux. The current theory predicts, from quite general considerations, that an unreasonably large intensity of cosmic rays, by many orders of magnitude, would be required in the interstellar medium to account for the observed fluxes. Conceivably, the current modulation theory could be modified so that only reasonable interstellar fluxes are predicted. One such modification involves an unusual scheme for particle diffusion in the interplanetary medium. Particles are assumed to diffuse not as a result of their own motion among small-scale irregularities in the magnetic field, but rather in a process in which they are trapped between time-varying constrictions in the large-scale field.
    Schlagwort(e): SPACE RADIATION
    Materialart: Astrophysical Journal; 206; May 15
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  • 53
    Publikationsdatum: 2011-08-16
    Beschreibung: Results are presented for detailed Monte Carlo calculations of the interaction histories of ultrahigh-energy cosmic-ray nuclei with intergalactic radiation fields, using improved estimates of these fields and empirical determinations of photonuclear cross sections, including multinuclear disintegrations for nuclei up to Fe-56. Intergalactic and galactic energy-loss rates and nucleon-loss rates for nuclei up to Fe-56 are also given. Astrophysical implications are discussed in terms of expected features in the cosmic-ray spectrum between 10 to the 18th and 10 to the 21st power eV for the universal and supercluster origin hypotheses. The results of these calculations indicate that ultrahigh-energy cosmic rays cannot be universal in origin regardless of whether they are protons or nuclei. Both the supercluster and galactic origin hypotheses, however, are possible regardless of nuclear composition.
    Schlagwort(e): SPACE RADIATION
    Materialart: Astrophysical Journal; 205; Apr. 15
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  • 54
    Publikationsdatum: 2011-08-16
    Beschreibung: Cosmic rays interact with mesoscale configurations of the interplanetary magnetic field. A technique is presented for calculating such configurations in the inner solar system, which are due to streams and source conditions near the sun, and maps of magnetic field are constructed for some plausible stream and source conditions. One effect of these mesoscale configurations on galactic cosmic rays is shown to be an out-of-the-ecliptic gradient drift sufficient to explain Forbush decreases. The effects on solar energetic particles include small polar drifts due to the field gradients and a possibly large modification of the time-intensity profiles and anisotropy characteristics due to the formation of mirror configurations in space. If a diffusion model is applicable to solar particles, the true diffusion coefficient will be masked by the effects of streams. A conceptual model which incorporates these ideas and those of several other models is presented.
    Schlagwort(e): SPACE RADIATION
    Materialart: Journal of Geophysical Research; 81; May 1
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  • 55
    Publikationsdatum: 2011-08-16
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: International Journal of Solids and Structures; 12; 8, 19; 1976
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  • 56
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    Publikationsdatum: 2011-08-16
    Beschreibung: The Galerkin method is used to investigate the large-amplitude free vibrations of simply supported and clamped tapered beams of rectangular cross-section which are frequently encountered in practical structures. Two types of linear tapers are considered: breadth and depth tapers. Two solutions are obtained for each type of taper, using trigonometric and polynomial displacement distributions. Frequency-amplitude relationships are obtained for all these cases for the fundamental flexural mode. The results indicate good agreement between trigonometric and polynomial solutions for all cases. The nonlinearity is noted to be always of the hardening type and, as expected, it is severe for beams with depth taper as compared with beams with breadth taper.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: AIAA Journal; 14; Feb. 197
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  • 57
    Publikationsdatum: 2011-08-16
    Beschreibung: Corotating proton and electron streams are the dominant type of low-energy (i.e., 0.1-10 MeV per nucleon) particle event observed at 1 AU. The radial dependence of these events has been studied between 1 and 4 AU using essentially identical low-energy detector systems on IMP-7, Pioneer-10, and Pioneer-11. It had been expected that at a given energy, the intensity of these streams would decrease rapidly with heliocentric distance due to the effects of interplanetary adiabatic deceleration. Instead, it is observed that from event to event, the intensity either remains roughly constant or increases significantly (more than an order of magnitude) between 1 and 4 AU. It appears that interplanetary acceleration processes are the most plausible explanation. Several possible acceleration models are discussed.
    Schlagwort(e): SPACE RADIATION
    Materialart: Astrophysical Journal; 203; Feb. 1
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  • 58
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    In:  Other Sources
    Publikationsdatum: 2011-08-16
    Beschreibung: Mathematical programming techniques provide a general approach to automated structural design. An iterative method is proposed in which design is treated as a hierarchy of subproblems, one being locally constrained and the other being locally unconstrained. It is assumed that the design space is locally convex in the case of good initial designs and that the objective and constraint functions are continuous, with continuous first derivatives. A general design algorithm is outlined for finding a move direction which will decrease the value of the objective function while maintaining a feasible design. The case of one-dimensional search in a two-variable design space is discussed. Possible applications are discussed. A major feature of the proposed algorithm is its application to problems which are inherently ill-conditioned, such as design of structures for optimum geometry.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: International Journal for Numerical Methods in Engineering; 10; 3, 19; 1976
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  • 59
    Publikationsdatum: 2011-08-17
    Beschreibung: Tests were conducted in a small wind tunnel to study the torsional stall flutter behavior of a two-dimensional flat-plate wing pivoted about the midchord. The nonlinear static divergence equilibrium properties of the wing were well predicted from the measured static moment characteristics. Large amplitude limit cycles ranging from plus or minus 11 degrees to plus or minus 100 degrees were observed. Stall flutter occurred above a critical value of a reduced frequency of about 2. Self-excitation occurred for initial angles of attack between 0 and 8 degrees. Nondimensional harmonic coefficients were extracted from the free transient vibration tests for amplitudes up to 80 degrees.
    Schlagwort(e): STRUCTURAL MECHANICS
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  • 60
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    Publikationsdatum: 2011-08-17
    Beschreibung: Arrays of fibers made of scintillating material were used as position-sensitive detectors or hodoscopes for beam-finding at ion accelerators. Experiments were made with alpha's from an Am241 source incident upon one end of the fiber, the other end being viewed with a photomultiplier tube. The scintillation light was not detected in any of the fibers tested beyond about 5 cm. The effective useful lengths for detection of relativistic heavy ions were given.
    Schlagwort(e): SPACE RADIATION
    Materialart: The Specific Light Output of Cesium Iodide Crystals; p 59-63
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  • 61
    Publikationsdatum: 2011-08-16
    Beschreibung: The paper examines the medium-energy (about 10-30 MeV) galactic gamma-ray radiation from primary and secondary electrons and calculates the expected gamma-ray distribution for the specific model of Bignami et al. (1975) on the assumption that the cosmic rays are correlated with the matter on the scale of galactic arms. The energy spectrum typical of regions near the galactic center indicates a dramatic shift from a predominantly cosmic-ray nucleonic mechanism at higher energies to a cosmic-ray electron mechanism at the lower energies. This provides a most important and direct means of probing the cosmic-ray electrons as a function of galactic position by making gamma-ray observations in the few to 40 MeV energy range. Medium-energy gamma-ray astronomy is shown to be a valuable tool in galactic research.
    Schlagwort(e): SPACE RADIATION
    Materialart: Astrophysical Journal; 208; Aug. 15
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  • 62
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    Publikationsdatum: 2011-08-16
    Beschreibung: The papers in this volume deal essentially with the question whether the amplification of noise is due to the jet noise phenomenon or perhaps an interaction of airframe and core engine noise. In the area of jet noise suppression, various promising suppressor concepts are examined. The swirling flow jet noise suppressor is shown to provide significant noise reduction with minimal thrust losses. Progress in the aircraft engine core noise problem is reflected by seven research-type papers. Two possible mechanisms are seen to be responsible for core noise. One is the direct noise radiated from the turbulent combustion in the primary combuster and transmitted through the turbine, passing out the nozzle into the far field. The other mechanism is the noise that is emitted from hot spots being convected through the turbine. Which of these mechanisms (or perhaps both mechanisms) is responsible for core noise, and what are the coupling mechanisms of core engine noise and jet noise are the questions confronting researchers.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
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  • 63
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    Publikationsdatum: 2011-08-16
    Beschreibung: The problem of the stability of a three-dimensional crack is analyzed within a lattice-statics approximation. The consequence of introducing a jog into the crack face as well as the effects of various nonlinear-force laws are studied. The phenomenon of lattice trapping (upper and lower bounds on the applied stress for an equilibrium crack of given length) is again obtained. It is possible to obtain some physical insight into which aspects of the force law are critical for crack stability. In particular, the inadequacy of a thermodynamic approach - which relates the critical stress to a surface energy corresponding to the area under the cohesive-force-vs-displacement curve - is demonstrated. Surface energy is a global property of the cohesive-force law. Crack stability is sensitive to much more refined aspects of the cohesive-force law. Crack healing is sensitive to the long-range portion of the cohesive force. Crack expansion is sensitive to the position of the maximum in the cohesive-force relation.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: Journal of Applied Physics; 47; Feb. 197
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  • 64
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    Publikationsdatum: 2011-08-16
    Beschreibung: The paper reviews the current status of observational research into the highly puzzling problem of cosmic gamma-ray bursts. Up to now there is no convincing temporal or spatial correlation with any known celestial processes or objects. The typical burst source strength is somewhere between 10 to the 26th power ergs and 10 to the 52nd power ergs. A list of 39 confirmed and 9 unconfirmed cosmic gamma-ray bursts observed by satellite is given, showing times of occurrence and in some cases, the size in erg per square centimeter. Several approaches to the problem of source object identification are discussed: (1) accumulation of observation statistics with their present poor resolution and research for correlative phenomena, (2) mapping out celestial source distributions with moderate resolution in order to search for galactic or other anisotropies in direction or to look for repeating source regions, and (3) very high-accuracy localization of the source directions of one or several bursts in order to pinpoint a tiny fraction of the celestial sphere for correlative radio, optical and X-ray studies. Planned future instrumentation for deep space probes and multiple-balloon studies is described.
    Schlagwort(e): SPACE RADIATION
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  • 65
    Publikationsdatum: 2011-08-16
    Beschreibung: Symmetric structure matrices are derived for solving plane strain and axisymmetric problems involving incompressible hyperelastic materials. An infinite hollow cylinder subjected to internal pressure is considered as an example. Displacement and hydrostatic pressure profiles are calculated using the Newton-Raphson iteration technique. The results are in good agreement with the exact curves.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: AIAA Journal; 14; Mar. 197
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  • 66
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    Publikationsdatum: 2011-08-16
    Beschreibung: A general set of finite-element equations is developed for treating the nonlinear dynamic response of membranes consisting of complex nonlinear materials. The approach proposed by Key (1974) for a most complete treatment of the finite-element method to the nonlinear dynamic analysis of solids is used in developing the nonlinear equations of motion for membranes with cubic quadrilateral finite elements. The computations are kept general with respect to material modeling by computing the deformation gradient and requiring a constitutive subroutine to supply the Cauchy stress. An example calculation of the vibration of a square membrane demonstrates the accuracy of the formulation for small deformation theory and shows the nonlinear effect of large deformations.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: American Society of Civil Engineers; Journal
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  • 67
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    Publikationsdatum: 2011-08-16
    Beschreibung: The paper deals with a method of optimizing harmonically or dynamically excited structures which removes the frequency constraint (that specifies that the structure's first natural frequency of vibration must be greater than the excitation frequency), replaces the displacement constraint by an inequality constraint on the allowable stress and applies finite element approximations to the continuous one-dimensional structures. When the problem is posed in this manner, the feasible design space is disconnected or 'disjoint'. An attempt is made to explain this disjointness by studying the optimal design of a thin-walled cantilevered rod subjected to steady, simple harmonic torsional excitation. The finite element method is applied to the optimization of a harmonically excited structure with an arbitrary number of design variables, with the disjointness of the design space, a complicating factor.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: AIAA Journal; 14; Feb. 197
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  • 68
    Publikationsdatum: 2011-08-16
    Beschreibung: A plasma strong turbulence, weak coupling, theory is applied to the problem of cosmic-ray pitch-angle scattering in magnetostatic turbulence. The theory used is a rigorous generalization of Weinstock's 'resonance broadening' theory and contains no ad hoc approximations. A detailed calculation is presented for a model of 'slab' turbulence with an exponential correlation function. The results agree well with numerical simulations. The rigidity dependence of the pitch-angle scattering coefficient differs from that found by previous researchers. The differences result from an inadequate treatment of particle trajectories near 90 deg pitch angle in earlier work.
    Schlagwort(e): SPACE RADIATION
    Materialart: Astrophysical Journal; 204; Mar. 15
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  • 69
    Publikationsdatum: 2011-08-16
    Beschreibung: The flux density of cosmic-ray positrons and electrons was measured by a balloon-borne spark chamber magnetic spectrometer in two flights in an attempt to study the solar modulation of galactic cosmic rays. The total electron flux was found to be about 0.03/cu m/s/sr/MeV between 70 and 800 MeV and to increase toward lower energies, while the positron flux decreased sharply toward lower energies from about 0.008/cu m/s/sr/MeV at 650 MeV and only upper limits were obtained for positrons below 200 MeV. At energies above 180 MeV, the spherically symmetrical Fokker-Planck equation with a diffusion coefficient proportional to the particle rigidity provided a reasonable fit to both positron and total electron data, while at energies below 180 MeV, the data were consistent with a continuation of the same diffusion coefficient and local source of electrons, or a change in the diffusion coefficient to a constant value.
    Schlagwort(e): SPACE RADIATION
    Materialart: Astrophysical Journal; 204; Mar. 15
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  • 70
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    Publikationsdatum: 2011-08-16
    Beschreibung: The indirect method of estimating the diffuse metagalactic flux of ionizing radiation proposed by Sunyaev (1969) is reconsidered in the light of further studies of the interaction of this radiation with galactic gas. An upper limit is derived for the intensity of the metagalactic background radiation to which the neutral interstellar medium is exposed. This limit on the ionizing radiation flux severely restricts the emission from a galactic corona containing gas in the temperature range 100,000 to 1,000,000 K. An upper limit of 10 to the 29.2 erg/sec/Hz is obtained for the mean luminosity radiated by a quasar in the energy band 40-170 eV. The 21-cm observations examined indicate that further than about 30 kpc from the center of the galaxy self-shielding by H II is possible only when the critical metagalactic ionizing flux is not exceeded.
    Schlagwort(e): SPACE RADIATION
    Materialart: Nature; 260; Apr. 8
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  • 71
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    In:  CASI
    Publikationsdatum: 2016-06-07
    Schlagwort(e): SPACE RADIATION
    Materialart: Lunar Science Inst., Abstracts of Papers Presented at a Special Session of the Seventh Annual Lunar Science Conference on Utilization of Lunar Materials and Expertise for Large Scale Operations in Space; p 81-86
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  • 72
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    In:  CASI
    Publikationsdatum: 2017-10-02
    Beschreibung: The effects of afterburner light-off and shut-down transients on the compressor stability are investigated. The reported experimental results are based on detailed high response pressure and temperature measurements on the TF30-P-3 turbofan engine. The tests were performed in an altitude test chamber simulating high altitude engine operation. It is shown that during both types of transients, flow breaks down in the forward part of the fan bypass duct. At a sufficiently low engine inlet pressure this resulted in a compressor stall. Complete flow breakdown within the compressor was preceded by a rotating stall. At some locations in the compressor, rotating stall cells initially extended only through part of the blade span. For the shutdown transient the time between first and last detected occurrence of rotating stall is related to the flow Reynolds number. An attempt was made to deduce the number and speed of propagation of rotating stall cells.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: AGARD Unsteady Phenomena in Turbomachinery; 12 p
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  • 73
    Publikationsdatum: 2017-10-02
    Beschreibung: Propulsion systems are evaluated in terms of relative aircraft range for a fixed payload and takeoff gross weight with a design cruise Mach number of 2.7. In order to put the performance of these engines in perspective, a comparison of these engines and the former U.S. SST engine is made with an idealized variable cycle engine whose performance at all operating points matches that of an optimized point design cycle within specified limits. Range comparisons are made with and without noise level constraints to determine the influence of noise upon cycle selection. The critical areas requiring new or improved technology for each cycle are delineated.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: AGARD Variable Geometry and Multicycle Eng.; 19 p
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  • 74
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    In:  CASI
    Publikationsdatum: 2016-06-07
    Beschreibung: A finite element analysis procedure built around the NASTRAN system is assessed. A number of support programs that were either written or modified to interface with NASTRAN and some improvements that were made to NASTRAN itself are noted. Some typical models are analyzed and an actual schedule is followed for constructing and analyzing the models to support a large design program.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Ames Res. Center NASTRAN: User's Experiences; p 531-554
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  • 75
    Publikationsdatum: 2016-06-07
    Beschreibung: The application of NASTRAN to seismic analysis by considering the example of a nuclear power plant control panel was considered. A modal analysis of a three-dimensional model of the panel, consisting of beam and quadri-lateral membrane elements, is performed. Using the results of this analysis and a typical response spectrum of an earthquake, the seismic response of the structure is obtained. ALTERs required to the program in order to compute the maximum modal responses as well as the resultant response are given. The results are compared with those obtained by using the SAP IV computer program.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Ames Res. Center MATRAN: User's Experiences; p 515-530
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  • 76
    Publikationsdatum: 2016-06-07
    Beschreibung: The Level 16 flutter analysis capability was applied to an aspect-ratio-6.8 subsonic transport type wing, an aspect-ratio-1.7 arrow wing, and an aspect-ratio-1.3 all movable horizontal tail with a geared elevator. The transport wing and arrow wing results are compared with experimental results obtained in the Langley transonic dynamic tunnel and with other calculated results obtained using subsonic lifting surface (kernel function) unsteady aerodynamic theory.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASTRAN: User's Experiences; p 495-512
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  • 77
    Publikationsdatum: 2016-06-07
    Beschreibung: NASTRAN analysis results are scanned to determine maximum and minimum displacements, forces and stresses. Allowables and margins of safety are computed, and in the case of multiple loading conditions, envelopes for displacements, forces, stresses and margins of safety are also produced for specified element sets. Graphical plots of the reduced or the regular NASTRAN results may be obtained superimposed either of a developed fuselage strip or on a projection of any specified part of the finite element model. The use of the data reduction, post analysis and graphical plotting capabilities provide the analyst with a fast and convenient tool for the study of NASTRAN analysis results and their presentation for project documentation.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Ames Res. Center NASTRAN: User's Experiences; p 555-580
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  • 78
    facet.materialart.
    Unbekannt
    In:  CASI
    Publikationsdatum: 2016-06-07
    Beschreibung: Two plate elements, the linear strain triangular membrane element CTRIM6 and the higher order plate bending element CTRPLT1, were added to NASTRAN Level 16.0. The theoretical formulation, programming details, and bulk data information pertaining to the addition of these elements are discussed. Sample problems illustrating the use of these elements are presented.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Ames Res. Center NASTRAN: User's Experiences; p 439-478
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  • 79
    Publikationsdatum: 2016-06-07
    Beschreibung: A computer code for the analysis of reinforced concrete structures was developed using NASTRAN as a basis. Nonlinear iteration procedures were developed for obtaining solutions with a wide variety of loading sequences. A direct access file system was used to save results at each load step to restart within the solution module for further analysis. A multi-nested looping capability was implemented to control the iterations and change the loads. The basis for the analysis is a set of mutli-layer plate elements which allow local definition of materials and cracking properties.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Ames Res. Center NASTRAN: User's Experiences; p 479-494
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  • 80
    Publikationsdatum: 2016-06-07
    Beschreibung: The quadratic isoparametric elements which embody the inverse square root singularity are used for calculating the stress intensity factors at tips of cracks. The strain singularity at a point or an edge is obtained in a simple manner by placing the mid-side nodes at quarter points in the vicinity of the crack tip or an edge. These elements are implemented in NASTRAN as dummy elements. The method eliminates the use of special crack tip elements and in addition, these elements satisfy the constant strain and rigid body modes required for convergence.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Ames Res. Center NASTRAN: User's Experiences; p 419-438
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  • 81
    Publikationsdatum: 2016-06-07
    Beschreibung: Two NASTRAN models of the Gates Learjet Corporation Model 35/36 Wing were developed. The models and the problems encountered in their development are discussed. A skin buckling analysis used for the ultimate loading conditions is presented. A discussion of the static tests and the correlation of the static test with the NASTRAN results and the results of a supplementary semimonocoque beam analysis are also included.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Ames Res. Center NASTRAN: User's Experiences; p 331-352
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  • 82
    Publikationsdatum: 2016-06-07
    Beschreibung: The application of NASTRAN to design studies of two very large-area lightweight structures is described. The first is the Satellite Solar Power Station, while the second is a deployable three hundred meter diameter antenna. A brief discussion of the operation of the SSPS is given, followed by a description of the structure. The use of the NASTRAN program for static, vibration and thermal analysis is illustrated and some results are given. Next, the deployable antenna is discussed and the use of NASTRAN for static analysis, buckling analysis and vibration analysis is detailed.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Ames Res. Center NASTRAN: User's Experiences; p 295-330
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  • 83
    Publikationsdatum: 2016-06-07
    Beschreibung: Selected examples are described in which NASTRAN is used as an analysis research tool for composite mechanics and for composite structural components. The examples were selected to illustrate the importance of using NASTRAN as an analysis tool in this rapidly advancing field.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASTRAN: User's Experiences; p 381-418
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  • 84
    Publikationsdatum: 2016-06-07
    Beschreibung: A summary of fluid/structure interaction capabilities for the NASTRAN computer program is presented. Indirect applications of the program towards solving this class of problem were concentrated on. For completeness and comparitive purposes, direct usage of NASTRAN is briefly discussed. The solution technology addresses both steady state and transient dynamic response problems.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Ames Res. Center NASTRAN: User's Experiences; p 229-250
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  • 85
    Publikationsdatum: 2016-06-07
    Beschreibung: A method is described from which the interaction of an elastic structure with an infinite acoustic fluid is determined. The displacements of the structure and the pressure field of the immediate surrounding fluid are modeled by finite elements, and the remaining pressure field of the infinite fluid region is given by an analytical expression. This method yields a frequency dependent boundary condition for the outer fluid boundary when applied to the frequency response of an elastic beam in contact with an acoustic fluid. The frequency response of the beam is determined using NASTRAN, and compares favorably to the exact solution which is also presented. The effect of the fluid on the response of the structure at low and high frequencies is due to added mass and damping characteristics, respectively.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Ames Res. Center NASTRAN: User's Experiences; p 251-272
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  • 86
    Publikationsdatum: 2016-06-07
    Beschreibung: Stresses and deformations in thick, short, composite cylinder subjected to axially varying radial pressure are studied. Effect of slippage at the interface is examined. In the NASTRAN finite element model, multipoint constraint feature is utilized. Results are compared with theoretical analysis and SAP-IV computer code. Results from NASTRAN computer code are in good agreement with the analytical solutions. Results suggest a considerable influence of interfacial slippage on the axial bending stresses in the cylinder.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Ames Res. Center NASTRAN: User's Experiences; p 161-176
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  • 87
    facet.materialart.
    Unbekannt
    In:  CASI
    Publikationsdatum: 2016-06-07
    Beschreibung: NASTRAN contains two techniques to solve the differential stiffness problems. One is incorporated in a new static analysis rigid format and the other is contained in a new normal modes analysis rigid format. The two techniques relative to computational accuracy and time of execution are compared.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Ames Res. Center NASTRAN: User's Experiences; p 149-160
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  • 88
    Publikationsdatum: 2016-06-07
    Beschreibung: A detailed description is given of how the decoupling approximation known as the doubly asymptotic approximation is implemented with NASTRAN to solve shock problems for submerged structures. The general approach involves locating the nonsymmetric terms (which couple structural and fluid variables) on the right hand side of the equations. This approach results in coefficient matrices of acceptable bandwidth but degrades numerical stability, requiring a smaller time step size than would otherwise be used. It is also shown how the structure's added (virtual) mass matrix, is calculated with NASTRAN.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Ames Res. Center NASTRAN: User's Experiences; p 207-228
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  • 89
    facet.materialart.
    Unbekannt
    In:  CASI
    Publikationsdatum: 2016-06-07
    Beschreibung: An overview of four analysis capabilities, which developed and integrated into the NASTRAN Thermal Analyzer, is given. To broaden the scope of applications, these additions provide the NTA users with the following capabilities: (1) simulating a thermal louver as a means of the passive thermal control, (2) simulating a fluid loop for transporting energy as a means of the active thermal control, (3) condensing a large sized finite element model for an efficient transient thermal analysis, and (4) entering multiple boundary condition sets in a single submission for execution in steady state thermal analyses.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASTRAN: User's Experiences; p 119-126
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  • 90
    Publikationsdatum: 2016-06-07
    Beschreibung: Implementation of the tridiagonal reduction method for real eigenvalue extraction in structural vibration and buckling problems is described. The basic concepts underlying the method are summarized and special features, such as the computation of error bounds and default modes of operation are discussed. In addition, the new user information and error messages and optional diagnostic output relating to the tridiagonal reduction method are presented. Some numerical results and initial experiences relating to usage in the NASTRAN environment are provided, including comparisons with other existing NASTRAN eigenvalue methods.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASTRAN" User's Experiences; p 127-148
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  • 91
    Publikationsdatum: 2016-06-07
    Beschreibung: The NTA Level 15.5.2/3, was used to provide non-linear steady-state (NLSS) and non-linear transient (NLTR) thermal predictions for the International Ultraviolet Explorer (IUE) Scientific Instrument (SI). NASTRAN structural models were used as the basis for the thermal models, which were produced by a straight forward conversion procedure. The accuracy of this technique was sub-sequently demonstrated by a comparison of NTA predicts with the results of a thermal vacuum test of the IUE Engineering Test Unit (ETU). Completion of these tasks was aided by the use of NTA subroutines.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASTRAN: User's Experiences; p 99-118
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  • 92
    facet.materialart.
    Unbekannt
    In:  CASI
    Publikationsdatum: 2016-06-07
    Beschreibung: An automated strength sizing capability is described. The technique determines the distribution of material among the elements of a structural model. The sizing is based on either a fully stressed design or a scaled feasible fully stressed design. Results obtained from the application of the strength sizing to the structural sizing of a composite material wing box using material strength allowables are presented. These results demonstrate the rapid convergence of the structural sizes to a usable design.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Ames Res. Center NASTRAN: User's Experiences; p 53-66
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  • 93
    facet.materialart.
    Unbekannt
    In:  CASI
    Publikationsdatum: 2016-06-07
    Beschreibung: Eight alternative modeling techniques to specify prescribed temperature at grid or scalar points for transient thermal analyses are presented. Four cases are for constant temperatures, and the others are time varying temperature functions. Theoretical explications and detailed listing of input data cards used for illustrating different modelings are given. It is shown that the NTA is exploited to extend beyond its normal capabilities through innovative modeling techniques. In addition, the effect of node valency on the energy distribution grid points is illustrated and discussed. Guidelines to delineate this effect are given.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASTRAN: User's Experiences; p 3-20
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  • 94
    Publikationsdatum: 2016-06-07
    Beschreibung: A procedure for the local stiffness modifications of large structures is described. It enables structural modifications without an a priori definition of the changes in the original structure and without loss of efficiency due to multiple loading conditions. The solution procedure, implemented in NASTRAN, involved the decomposed stiffness matrix and the displacement vectors of the original structure. It solves the modified structure exactly, irrespective of the magnitude of the stiffness changes. In order to investigate the efficiency of the present procedure and to test its applicability within a design environment, several real and large structures were solved. The results of the efficiency studies indicate that the break-even point of the procedure varies between 8% and 60% stiffness modifications, depending upon the structure's characteristics and the options employed.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Ames Res. Center NASTRAN: User's Experiences; p 21-52
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  • 95
    Publikationsdatum: 2016-06-07
    Beschreibung: Flat panel flutter at high supersonic Mach number is analyzed using NASTRAN Level 16.0 by means of modifications to the code. Two-dimensional plate theory and quasi-steady aerodynamic theory are employed. The finite element formulation and solution procedure are presented. Modifications to the NASTRAN code are discussed. Convergence characteristics of the iteration processes are also briefly discussed. Effects of aerodynamic damping, boundary support condition and applied in-plane loading are included. Comparison of nonlinear vibration and linear flutter results with analytical solutions demonstrate that excellent accuracy is obtained with NASTRAN.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASTRAN: User's Experiences; p 67-98
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  • 96
    facet.materialart.
    Unbekannt
    In:  CASI
    Publikationsdatum: 2016-06-07
    Beschreibung: Improvements in the NASTRAN systems management office are presented. Among the improvements are the following items: (1) the FEER eigenmethod and its extension to complete eigenvalue problems; (2) the addition of a supersonic flutter package which allows gust response calculations and active control effects as membrane In addition to capabilities mentioned, an error correction information system is also introduced.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASTRAN: User's Experiences; p 1-2
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  • 97
    facet.materialart.
    Unbekannt
    In:  CASI
    Publikationsdatum: 2016-06-07
    Beschreibung: A flight program to measure atmospheric turbulence at high altitudes (long wavelengths) in a variety of meteorological conditions is described and some results obtained in high altitude wind shear are discussed. Results are also presented from wind tunnel test programs to measure fluctuating pressures associated with over-the-wing configurations. A flexible aircraft take off and landing analysis and an active control landing gear analysis, are developed and their capabilities are described. Efforts to validate these analyses with experimental data are also discussed as well as results obtained from parametric studies.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: Proc. of the SCAR Conf., Pt. 2,; 22 p
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  • 98
    facet.materialart.
    Unbekannt
    In:  CASI
    Publikationsdatum: 2016-06-07
    Beschreibung: The status of the Federal Aviation Administration's High Altitude Pollution Program is described which was instituted to develop the detailed quantitative information needed to judge whether or not regulatory action to limit such exhaust emissions would be necessary. The complexities of this question and the nature and magnitude of uncertainties still present in our scientific understanding of the potential interactions between aircraft exhaust emissions and stratospheric ozone and climate are reviewed. The direction and scope of future Federal and international activities are described.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA. Langley Res. Center Proc. of the SCAR Conf., Pt. 2,; 10 p
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  • 99
    Publikationsdatum: 2016-06-07
    Beschreibung: Various experiments are sponsored and conducted by NASA to explore the potential of advanced combustion techniques for controlling aircraft engine emissions into the upper atmosphere. Of particular concern are the oxide of nitrogen (NOx) emissions into the stratosphere. The experiments utilize a wide variety of approaches varying from advanced combustor concepts to fundamental flame tube experiments. Results are presented which indicate that substantial reductions in cruise NOx emissions should be achievable in future aircraft engines. A major NASA program is described which focuses the many fundamental experiments into a planned evolution and demonstration of the prevaporized-premixed combustion technique in a full-scale engine.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: Proc. of the SCAR Conf., Pt. 2,; 22 p
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  • 100
    Publikationsdatum: 2016-06-07
    Beschreibung: Two engine components, fan blades and exhaust systems, were selected for composite materials development efforts in support of the supersonic cruise aircraft research (SCAR) engine program. The materials selected were boron/aluminum for fan blades and silicon carbide/superalloy sheet for the exhaust system. The current status of the research into applying these two composite materials to SCAR engines is reviewed.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: Proc. of the SCAR Conf., Part 1; p 457-468
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