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  • Other Sources  (9)
  • ASTROPHYSICS  (6)
  • ACOUSTICS  (3)
  • General Chemistry
  • Polymer and Materials Science
  • 1975-1979  (9)
  • 1
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    Evidence for a 17d periodicity from Cyg X-3 (1976)
    In:  CASI
    Details
    Publication Date: 2006-04-18
    Description: Data which indicate a periodicity of 17d from Cyg X-3 are reviewed. The data are taken from the Ariel 5 satellite All-Sky Monitor and the Sky Survey Experiment.
    Keywords: ASTROPHYSICS
    Type: X-ray Binaries; p 245-253
    Format: text
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  • 2
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    Evidence for a 17-d periodicity from Cyg X-3 (1976)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: Data are presented from the Ariel-V All-Sky Monitor which indicate a 17-day periodicity of the X-ray spectra from Cyg X-3 (3U2030+40). The data are consistent with data from the Ariel V Sky Survey Experiment. Assuming that the high intensity state of Cyg X-3 is well fitted by a structureless black body (Serlemitsos et al., 1975), and that the 17-day maxima correspond to increased electron scattering in the source, it is suggested that the 17-day effect is analogous to the 35-day variation in Her X-1. The possible explanation of this phenomenon as a result of the 17-day orbital period of the binary system containing Cyg X-3 is severely constrained by the stability of the well-known 4.8-hour variation.
    Keywords: ASTROPHYSICS
    Type: Nature; 260; Apr. 15
    Format: text
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  • 3
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    Observations of far-infrared fine structure lines - Forbidden O III 88.35 microns and forbidden O I 63.2 microns (1979)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Results are presented for observations of the fine-structure lines of forbidden O III at 88.35 microns and forbidden O I at 63.2 microns in a number of sources by means of an airborne far-IR spectrometer. The sources M17, NGC 7538, and W51 are mapped in the forbidden O III line with a resolution of 1 arcmin, and the emission peak is found to coincide with the maximum radio continuum in all cases. The far-IR continuum is simultaneously mapped where possible; the continuum peak is shown to be distinct from the center of ionization in the same three sources. The forbidden O III line is also detected in W3, W49, and several positions in M42 (Orion). The forbidden O I line is detected in M17, in M42, and marginally in DR 21. An unsuccessful search for the J = 1-0 transition of HD at 112 microns in the direction of the Kleinmann-Low nebula is also reported.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 233
    Format: text
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  • 4
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    A comparison of matrix methods for calculating eigenvalues in acoustically lined ducts (1976)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Three approximate methods - finite differences, weighted residuals, and finite elements - were used to solve the eigenvalue problem which arises in finding the acoustic modes and propagation constants in an absorptively lined two-dimensional duct without airflow. The matrix equations derived for each of these methods were solved for the eigenvalues corresponding to various values of wall impedance. Two matrix orders, 20 x 20 and 40 x 40, were used. The cases considered included values of wall admittance for which exact eigenvalues were known and for which several nearly equal roots were present. Ten of the lower order eigenvalues obtained from the three approximate methods were compared with solutions calculated from the exact characteristic equation in order to make an assessment of the relative accuracy and reliability of the three methods. The best results were given by the finite element method using a cubic polynomial. Excellent accuracy was consistently obtained, even for nearly equal eigenvalues, by using a 20 x 20 order matrix.
    Keywords: ACOUSTICS
    Type: NASA-TN-D-8186 , L-10607
    Format: application/pdf
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  • 5
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    The light curve of a transient X-ray source (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The Ariel-V satellite monitored the X-ray light curve of A1524-62 almost continuously from 40 days prior to maximum light until its disappearance below the effective experimental sensitivity. The source exhibited maximum light on approximately 4 December 1974, at a level of 0.9 the apparent magnitude of the Crab Nebula in the energy band 3-6 keV. Although similar to previously reported transient sources with a decay time constant of approximately 2 months, the source exhibited an extended, variable pre-flare on-state of about 1 month at a level of greater than approximately 0.1 maximum light. The four bright (greater than 0.2 of the Crab Nebula) transient sources observed during the first half-year of Ariel-V operation are indicative of a galactic disk distribution, and a luminosity at maximum in excess of 10 to the 37th power ergs/sec.
    Keywords: ASTROPHYSICS
    Type: NASA-TM-X-70938 , X-661-75-178
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  • 6
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    A statistical theory of sound radiation from a two-dimensional lined duct (1979)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: A statistical theory coupled with a finite element theory is employed for investigation of sound radiation from a two-dimensional lined duct. The analysis does not utilize duct modes, and can be applied to a non-uniform duct with variable wall liner properties. Numerical results are presented for various shapes of the incident wave. The results are in good agreement with the Wiener-Hopf calculation for cases where the latter can be made.
    Keywords: ACOUSTICS
    Type: AIAA PAPER 79-1521 , American Institute of Aeronautics and Astronautics, Fluid and Plasma Dynamics Conference; Jul 23, 1979 - Jul 25, 1979; Williamsburg, VA
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  • 7
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    Radio detection of interstellar N2D/+/ (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Line emission from the J = 1-0 transition of interstellar N2D(+) has been detected toward the cool dust cloud L134 N. The N2H(+)/N2D(+) total-projected-density ratio in this cloud is estimated to be about 2.22. Upper limits are obtained for the fractional ionization as well as the CO and N2 abundances in L134 N. The results are shown to support the previously discovered enhancement of the abundance of deuterated molecules in cool dust clouds.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 218
    Format: text
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  • 8
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    Measurement and significance of the equilibrium reaction C-13/+/ + /C-12/O yields C-12/+/ + /C-13/O for alteration of the C-13/C-12 ratio in interstellar molecules (1976)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Laboratory measurements using the ion-cyclotron resonance technique yield a rate constant of 2 by 10 to the -10th power cu cm/sec at 300 K for the isotope exchange C-13(+) + (C-12)O yields C-12(+) + (C-13)O. According to the usual ideas about ion-molecule reactions, this rate constant should also be appropriate at temperatures not exceeding about 100 K. Then the observed C-13/C-12 ratio obtained from radio observation of interstellar molecules may be either larger or smaller than the actual value in the interstellar medium by factors of 2 or so. If the ratio is altered from the actual interstellar value, it will not be the same in all molecules, and CO will tend to have the highest value. The chief astronomical uncertainty for the occurrence of this isotope fractionation is the abundance of 'unobservable' molecules which can react rapidly with C(+): e.g., O2, H2O, CO2, and CH4. If their abundance is greater than about one-tenth that of CO, the isotope fractionation will be inhibited.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; 205; May 1
    Format: text
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  • 9
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    A finite element simulation of sound attenuation in a finite duct with a peripherally variable liner (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Using multimodal analysis, a variational finite element method is presented for analyzing sound attenuation in a three-dimensional finite duct with a peripherally variable liner in the absence of flow. A rectangular element, with cubic shaped functions, is employed. Once a small portion of a peripheral liner is removed, the attenuation rate near the frequency where maximum attenuation occurs drops significantly. The positioning of the liner segments affects the attenuation characteristics of the liner. Effects of the duct termination are important in the low frequency ranges. The main effect of peripheral variation of the liner is a broadening of the attenuation characteristics in the midfrequency range. Because of matrix size limitations of the presently available computer program, the eigenvalue equations should be solved out of core in order to handle realistic sources.
    Keywords: ACOUSTICS
    Type: NASA-TM-74080 , Aeroacoust. Conf.; Oct 03, 1977 - Oct 05, 1977; Atlanta
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