ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • ASTROPHYSICS  (731)
  • STRUCTURAL MECHANICS  (466)
  • 1980-1984  (780)
  • 1970-1974  (417)
  • 1935-1939
  • 1980  (780)
  • 1974  (417)
Collection
Keywords
Years
  • 1980-1984  (780)
  • 1970-1974  (417)
  • 1935-1939
Year
  • 1
    facet.materialart.
    Unknown
    Short-range repulsive forces between atoms and molecules of atmospheric gases (1974)
    In:  CASI
    Details
    Publication Date: 2006-01-11
    Description: Experimental determination of the paired interaction potential of atoms and molecules composing the atmospheres of the earth and the planets is described.
    Keywords: ASTROPHYSICS
    Type: Interplanet. Medium and Phys. of the Magnetosphere (NASA-TT-F-784); p 275-281
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 2
    facet.materialart.
    Unknown
    An investigation of the cosmic radiation in the vicinity of the moon on the Luna 10, 11, and 12 artificial lunar satellites (1974)
    In:  CASI
    Details
    Publication Date: 2006-01-11
    Description: Research on the primary cosmic radiation and solar cosmic rays from the Luna 10, 11, and 12 artificial lunar satellites is reviewed. Data on the vertical distribution of cosmic rays above the moon's surface are presented, and the albedo for the primary radiation is determined. The fluxes of electrons with energies from 30 to 300 keV were registered in the solar cosmic rays. Rapid variations of the electron flux were observed. The angular distributions of 0.5-10 MeV protons moving together with the corpuscular streams responsible for Forbush decreases were investigated.
    Keywords: ASTROPHYSICS
    Type: Interplanet. Medium and Phys. of the Magnetosphere (NASA-TT-F-784); p 151-173
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 3
    facet.materialart.
    Unknown
    Structural formations in the interplanetary medium (1974)
    In:  CASI
    Details
    Publication Date: 2006-01-11
    Description: Research on the fine structure of the interplanetary medium is reviewed. The characteristics of shock waves, filaments, and contact surfaces according to space probe measurements are discussed.
    Keywords: ASTROPHYSICS
    Type: Interplanet. Medium and Phys. of the Magnetosphere (NASA-TT-F-784); p 103-123
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 4
    facet.materialart.
    Unknown
    High-frequency turbulence in the cosmic plasma (1974)
    In:  CASI
    Details
    Publication Date: 2006-01-11
    Description: The problem of quasistationary high frequency Langmuir turbulence, which is one of the types of turbulence encountered in the cosmic plasma, is examined theoretically.
    Keywords: ASTROPHYSICS
    Type: Interplanet. Medium and Phys. of the Magnetosphere (NASA-TT-F-784); p 83-102
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 5
    facet.materialart.
    Unknown
    Dissipation of energy in model experiments (1974)
    In:  CASI
    Details
    Publication Date: 2006-01-11
    Description: Interaction studies of a plasma stream with a magnetic dipole have shown that the thickness of the plasma/field interlayer is considerably greater than the characteristic plasma dimension c/omega sub 0. Broadening of the layer is due to the formation of a collisionless shock wave. To demonstrate collisionless dissipation, the Joulean losses were calculated using the conductivity value obtained from the skin layer thickness. Analysis of the various physical processes showed that the hypothesis of collisionless dissipation of the directional plasma flow is justified.
    Keywords: ASTROPHYSICS
    Type: Interplanet. Medium and Phys. of the Magnetosphere (NASA-TT-F-784); p 59-67
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 6
    facet.materialart.
    Unknown
    Certain problems in the physics of the magnetosphere (1974)
    In:  CASI
    Details
    Publication Date: 2006-01-11
    Description: A review of experimental and theoretical studies devoted to analysis of physical processes in the magnetosphere is presented. Attention is focused on the interrelationships among the most important geophysical phenomena in the magnetosphere: magnetic storms, auroras, the radiation belts, and processes in the geomagnetic tail. Recommendations are submitted for future experiments that are needed for development of a theory of magnetospheric phenomena.
    Keywords: ASTROPHYSICS
    Type: Interplanet. Medium and Phys. of the Magnetosphere (NASA-TT-F-784); p 1-33
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 7
    facet.materialart.
    Unknown
    Noise and vibration level reduction by covering metal structures with layers of damping materials (1974)
    In:  CASI
    Details
    Publication Date: 2006-01-11
    Description: One of the most important methods of reducing the noise and vibration level is the damping of the secondary sources, such as metal plates, often used in vehicle structures, by means of covering materials with high internal viscosity. Damping layers are chosen at an optimum thickness corresponding to the frequency and temperature range in which a certain structure works. The structure's response corresponding to various real situations is analyzed by means of a measuring chain including electroacoustical or electromechanical transducers. The experimental results provide the dependence of the loss factor and damping transmission coefficient as a function of the damping layer thickness or of the frequency for various viscoelastic covering materials.
    Keywords: STRUCTURAL MECHANICS
    Type: The 4th Natl. Conf. on Acoustics, Vol. 1A (NASA-TT-F-15375); p 246-253
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 8
    facet.materialart.
    Unknown
    Vibration and recoil control of pneumatic hammers (1974)
    In:  CASI
    Details
    Publication Date: 2006-01-11
    Description: Vibration sources are described for pneumatic hammers used in the mining industry (pick hammers), in boiler shops (riveting hammers), etc., bringing to light the fact that the principal vibration source is the variation in air pressure inside the cylinder. The present state of the art of vibration control of pneumatic hammers as it is practiced abroad, and the solutions adopted for this purpose, are discussed. A new type of pneumatic hammer with a low noise and vibration level is presented.
    Keywords: STRUCTURAL MECHANICS
    Type: The 4th Natl. Conf. on Acoustics, Vol. 1A (NASA-TT-F-15375); p 79-84
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 9
    facet.materialart.
    Unknown
    Vibration control in forge hammers (1974)
    In:  CASI
    Details
    Publication Date: 2006-01-11
    Description: Special measures are discussed for calculating, designing and executing a forge hammer foundation, so that the vibrations that occur during its working will not be transmitted to neighboring machinery, workrooms and offices. These vibrations are harmful to the workers near the forge hammer.
    Keywords: STRUCTURAL MECHANICS
    Type: The 4th Natl. Conf. on Acoustics, Vol. 1A (NASA-TT-F-15375); p 73-78
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 10
    facet.materialart.
    Unknown
    Experimental determination of the vibration level in 5,100 kW electric locomotive assemblies (1974)
    In:  CASI
    Details
    Publication Date: 2006-01-11
    Description: Because of the high vibration level occurring during the running of electric locomotives, mechanical defects occur in the control mechanisms of auxiliary services. This fact has given rise to the necessity of determining the values of these vibrations in electric locomotives during their running. Measurements were conducted on the Craiova-Drobeta-Turnu Severin line, and measures to reduce the vibration level in electric locomotives were instituted.
    Keywords: STRUCTURAL MECHANICS
    Type: The 4th Natl. Conf. on Acoustics, Vol. 1A (NASA-TT-F-15375); p 50-54
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 11
    facet.materialart.
    Unknown
    Random vibrations of linear viscoelastic beams with lumped masses (1974)
    In:  CASI
    Details
    Publication Date: 2006-01-11
    Description: A method is presented of determining the mean square transversal deflection of an isotropic and homogeneous linear viscoelastic beam having a certain number of lengthwise distributed lumped masses. It is assumed that the beam is acted upon by a stationary random process uniformly distributed along the beam. The method is useful in vibration level control by means of additional lumped masses.
    Keywords: STRUCTURAL MECHANICS
    Type: The 4th Natl. Conf. on Acoustics, Vol. 1A (NASA-TT-F-15375); p 36-42
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 12
    facet.materialart.
    Unknown
    Random vibrations of quadratic damping systems (1974)
    In:  CASI
    Details
    Publication Date: 2006-01-11
    Description: An oscillating system with quadratic damping subjected to white noise excitation is replaced by a nonlinear, statistically equivalent system for which the associated Fokker-Planck equation can be exactly solved. The mean square responses are calculated and the optimum damping coefficient is determined with respect to the minimum mean square acceleration criteria. An application of these results to the optimization of automobile suspension damping is given.
    Keywords: STRUCTURAL MECHANICS
    Type: The 4th Natl. Conf. on Acoustics, Vol. 1A (NASA-TT-F-15375); p 29-35
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 13
    facet.materialart.
    Unknown
    The response of many-storied structures under seismic actions (1974)
    In:  CASI
    Details
    Publication Date: 2006-01-11
    Description: A seismic action which is characterized by the acceleration function of the seismic motion is analyzed. The equations of motion in the direction of the seismic action are determined for a completely rigid ground and for a ground with linear deformability characteristics (rotation deformability). The equation for the rotation motion is derived by considering elastic and viscoelastic properties of the foundation ground. The differential equations are written by treating the mechanical model of a many-storied structure as a fixed vertical beam with a uniformly distributed mass as well as with concentrated masses on each floor.
    Keywords: STRUCTURAL MECHANICS
    Type: The 4th Natl. Conf. on Acoustics, Vol. 1A (NASA-TT-F-15375); p 43-49
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 14
    facet.materialart.
    Unknown
    Insulation of nonlinear and random vibrations in the mining industry (1974)
    In:  CASI
    Details
    Publication Date: 2006-01-11
    Description: The insulation of nonlinear and random vibrations is considered for some ore preparing and sorting implements: rotary crushers, resonance screens, hammer mills, etc. The appearance of subharmonic vibrations is analyzed, and the conditions for their appearance are determined. A method is given for calculating the insulation of these vibrations by means of elastic elements made of rubber. The insulation of the random vibrations produced by Symons crushers is calculated by determining the transmissability and deformation of the insulation system for a narrow band random response.
    Keywords: STRUCTURAL MECHANICS
    Type: The 4th Natl. Conf. on Acoustics, Vol. 1A (NASA-TT-F-15375); p 22-28
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 15
    facet.materialart.
    Unknown
    A mathematical model for storied buildings subjected to automatic loom stresses (1974)
    In:  CASI
    Details
    Publication Date: 2006-01-11
    Description: Expressions are derived for the displacements of a many storied building subjected to the action of classical weaving looms located at different levels of the building. The building is regarded as a vertical fixed beam with a uniformly distributed mass as well as concentrated masses at each level. The calculation relations are obtained on the assumption of harmonic variation of the forces acting at each level as well as the assumption of narrow band stationary random excitatory forces.
    Keywords: STRUCTURAL MECHANICS
    Type: The 4th Natl. Conf. on Acoustics, Vol. 1A (NASA-TT-F-15375); p 15-21
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 16
    facet.materialart.
    Unknown
    Study of vibrations produced by a vibrating beam used for vibrating concretes (1974)
    In:  CASI
    Details
    Publication Date: 2006-01-11
    Description: For compacting concretes in building, vibrating beams are used. The vibrations are generated by inertial vibrators, and the beam is normally displaced by the operator by means of a handle that is elastically fastened to the beam by means of rubber pads. Considered are vibrations transmitted to the operator, taking into account the beam's shock vibration motions. The steady state motion of a dynamic beam pattern is studied, and results of experimental tests with existing equipment are presented.
    Keywords: STRUCTURAL MECHANICS
    Type: The 4th Natl. Conf. on Acoustics, Vol. 1A (NASA-TT-F-15375); p 9-14
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 17
    facet.materialart.
    Unknown
    Stresses in dome-shaped shells of revolution with discontinuities at the apex (1974)
    In:  CASI
    Details
    Publication Date: 2006-04-02
    Description: Asymptotic solutions of Novozhilov's equations of shells of revolution are derived for axisymmetric and first harmonic loadings. The solutions obtained are valid throughout the shallow and nonshallow regions. Stresses in dome shaped shells of revolution with a discontinuity in the form of a circular hole, a circular rigid insert, or a nozzle at the apex have been investigated. Numerical results are obtained for spheres, ellipsoids, and paraboloids, containing a discontinuity under a internal pressure and moment. Curves depicting stress distributions are given. The influence of three types of discontinuity on the stresses of the shells is also given.
    Keywords: STRUCTURAL MECHANICS
    Type: Multivariant Function Model Generation; 118 p
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 18
    facet.materialart.
    Unknown
    Current structural vibration problems associated with noise (1974)
    In:  CASI
    Details
    Publication Date: 2011-10-14
    Description: As the performance of aerospace vehicles has increased, the noise generated by the propulsion system and by the passage of the vehicle through the air has also increased. Further increases in performance are now underway for space vehicles such as the space shuttle vehicle and for short distance takeoff and landing (STOL) aircraft, and are being planned for supersonic aircraft. The flight profiles and design features of these high-performance vehicles are reviewed and an estimate made of selected noise-induced structural vibration problems. Considerations for the prevention of acoustic fatigue, noise transmission, and electronic instrument malfunction are discussed.
    Keywords: STRUCTURAL MECHANICS
    Type: AGARD Noise Mech.; 16 p
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 19
    facet.materialart.
    Unknown
    Neutron stars with main sequence binary companions as low luminosity X-ray sources (1974)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics; 37; 1, De; Dec. 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 20
    facet.materialart.
    Unknown
    The interaction of interstellar gas with stellar density wave packets (1974)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: We have numerically studied the interaction between interstellar gas and a gravitational perturbation produced by a fluctuation in the stellar mass distribution. For a simple equation of state, shock waves develop even if the gravitational perturbation is aperiodic and transient. In a medium which can change thermal phase, shocks do not form and the gas makes a transition directly to the cold, dense phase. The cold material has an anomalous velocity imparted to it by the gravitational perturbation and it becomes an accretion front moving through the hot gas and capturing it. The accretion fronts trigger thermal phase change on a large scale and can reproduce the extent of observed cold clouds. Furthermore their high mass is favorable to gravitational instability and subsequent star formation.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics; 36; 2, No; Nov. 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 21
    facet.materialart.
    Unknown
    The Apsidal-motion test for models of main-sequence stars (1974)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: Apsidal-motion constants, k2, have been determined for models of homogeneous main-sequence stars constructed with the new 'Thomas-Fermi' opacities of Carson. These models are similar to those constructed with the 'hydrogenic' opacities of Cox and Stewart up to about 7 solar masses, but yield smaller values of k2 at higher masses. Nevertheless, the new theoretical constants are still systematically too large compared with most of the empirical constants known for members of well-observed binary systems. Uniform rotation is found to lower the theoretical constants only slightly. The effect of normal evolution during core hydrogen burning, however, produces good detailed agreement with observations. The primary of alpha Vir is probably evolving normally if Carson's opacities are adopted.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; 194; Dec. 15
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 22
    facet.materialart.
    Unknown
    Main sequence models for massive zero-metal stars (1974)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: Zero-age main-sequence models for stars of 20, 10, 5, and 2 solar masses with no heavy elements are constructed for three different possible primordial helium abundances: Y=0.00, Y=0.23, and Y=0.30. The latter two values of Y bracket the range of primordial helium abundances cited by Wagoner. With the exceptions of the two 20 solar mass models that contain helium, these models are found to be self-consistent in the sense that the formation of carbon through the triple-alpha process during premain sequence contraction is not sufficient to bring the CN cycle into competition with the proton-proton chain on the ZAMS. The zero-metal models of the present study have higher surface and central temperatures, higher central densities, smaller radii, and smaller convective cores than do the population I models with the same masses.
    Keywords: ASTROPHYSICS
    Type: Astrophysics and Space Science; 31; Nov. 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 23
    facet.materialart.
    Unknown
    Interplanetary sector structure - 1970-1972 (1974)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: Determinations of interplanetary sector structure for the years 1970-1972 reveal the persistence of sector patterns during the decreasing portion of the solar cycle. The simple two-sector pattern of 1969 persists through 1970 but develops greater complexity in 1971-1972.-
    Keywords: ASTROPHYSICS
    Type: Journal of Geophysical Research; 79; Dec. 1
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 24
    facet.materialart.
    Unknown
    Distinctive patterns on the surface of slowly rotating stars whose oscillations are nonlinearly coupled (1974)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: Slowly rotating stars which are oscillating at small amplitude in a broad spectrum of g-modes should display strong surface nonuniformities if even weak nonlinear coupling exists between the modes. Oscillatory power will be concentrated into distinctive patterns which rotate rigidly in spite of differential rotation in the outer stellar layers. Each pattern rotates at a constant rate slower than the star as a whole according to a very simple law of rotation. Virtually all the rotation rates are within 9 per cent of the stellar rate. Evidence is cited that the sun may be oscillating, so other stars along the main sequence may be oscillating, also. If zones obeying the predicted rotation law can be detected in a star, then the rotation rate of the stellar interior becomes known, and differential rotation is negligible over most of the stellar mass.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; 193; Nov. 1
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 25
    facet.materialart.
    Unknown
    Inclusion of transverse shear deformation in finite element displacement formulations (1974)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: A stiffness matrix is derived for a beam element with transverse shear deformation. It is shown that straightforward energy minimization yields the correct stiffness matrix in displacement formulations when transverse shear effects are considered. Since the TIM4 beam element does not represent the geometric boundary conditions for a cantilever beam the rotation of the normal must be retained as a grid point degree of freedom.
    Keywords: STRUCTURAL MECHANICS
    Type: AIAA Journal; 12; Nov. 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 26
    facet.materialart.
    Unknown
    The ethynyl radical C2H - A new interstellar molecule (1974)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: Four new interstellar lines have been detected near 87.3 GHz. Based on laboratory ESR data these lines have been positively defined as hyperfine components of the lowest rotational transition of the ethynyl radical C2H. The observations gave precise values for the C2H rotation, spin-doubling, and hyperfine constants. C2H is probably one of the most abundant interstellar polyatomic molecules yet detected.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; 193; Nov. 1
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 27
    facet.materialart.
    Unknown
    Influence of opacity on the pulsational stability of massive stars with uniform chemical composition. II - Modified Kramers opacity (1974)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: The pulsational stability of massive, chemically homogeneous stars of Population I has been investigated for a range of simple opacity representations consisting of a straight sum of electron-scattering and modified Kramers opacity. The critical mass for stability against nuclear-energized pulsations is found to be extraordinarily sensitive to small changes in the coefficient and/or temperature exponent of the absorption part of the opacity law. A gradual increase in the atomic absorption (dominant near the stellar surface) first raises the critical mass, then restricts the upper mass limit for instability, and finally eliminates pulsational instability at all masses.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; 193; Nov. 1
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 28
    facet.materialart.
    Unknown
    Equation of state at ultrahigh densities. I (1974)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: Particular attention is given to the physics involved in the derivation of an equation of state for a density range from 10 g/ccm to 200,000 billion g/ccm and for the density region from 200,000 billion g/ccm to 2,000,000 billion g/ccm. Conditions in a high density regime with densities exceeding 500,000 billion g/ccm are examined. Equations of state for a gas of pure neutrons and for a gas of nucleons, electrons, and hyperons are considered.
    Keywords: ASTROPHYSICS
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 29
    facet.materialart.
    Unknown
    Cometary coma ions (1974)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: For comets whose nuclei are composed of water ice conglomerates it is shown that the ion H3O(+) can predominate to distances of 5000 km in the subsolar direction. Beyond this distance H2O(+) is the most important ion. The crossover point is a sensitive function of the rate of evaporation from the nucleus. The presence of ammonia or metals such as sodium, in concentrations greater than 0.1% H2O, can lead to NH4(+) and Na(+) ions.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; 193; Oct. 1
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 30
    facet.materialart.
    Unknown
    An empirical line-blanketing study of Am stars (1974)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: Metallic line-blanketing coefficients have been measured over the wavelength range from 3800 to 4700 A in a sample of 20 Am and normal A stars. An expression for the logarithmic iron abundance has been calibrated in terms of effective temperature and a mean line-blocking coefficient. This makes it possible to determine the atmospheric iron abundance in sharp-lined Am and A stars with an accuracy of better than plus or minus 0.1 dex, using only line-blocking measurements and a photometric effective temperature.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; 193; Oct. 1
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 31
    facet.materialart.
    Unknown
    Li production in alpha-alpha reactions (1974)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: The cross section for Li-7 production in alpha-alpha reactions is shown to be increased by about a factor of 2 due to the excitation levels of Li-7 and Be-7 at 478 keV and 431 keV, respectively. The cross section for Li-6 production, however, remains the same as calculated on the basis of the detailed balance principle. The lines at 478 keV and 431 keV may link Li-7 production to feasible gamma-ray observations.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics; 34; 3, Se; Sept
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 32
    facet.materialart.
    Unknown
    Microcraters formed in glass by projectiles of various densities (1974)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: An experiment was conducted investigating the effect of projectile density on the structure and size of craters in soda lime glass and fused quartz. The projectiles were spheres of polystyrene-divinylbenzene (PS-DVB), aluminum, and iron with velocities between 0.5 and 15 km/sec and diameters between 0.4 and 5 microns. The projectile densities spanned the range expected for primary and secondary particles of micrometer size at the lunar surface, and the velocities spanned the lower range of micrometeoroid velocities and the upper range of secondary projectile velocities. There are changes in crater morphology as the impact velocity increases, and the transitions occur at lower velocities for the projectiles of higher density. The sequence of morphological features of the craters found for PS-DVB impacting soda lime glass for increasing impact velocity, described in a previous work (Mandeville and Vedder, 1971), also occurs in fused quartz and in both targets with the more dense aluminum and iron projectiles. Each transition in morphology occurs at impact velocities generating a certain pressure in the target. High density projectiles require a lower velocity than low-density projectiles to generate a given shock pressure.
    Keywords: STRUCTURAL MECHANICS
    Type: Journal of Geophysical Research; 79; Aug. 10
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 33
    facet.materialart.
    Unknown
    Approximate techniques of structural reanalysis (1974)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: A study is made of two approximate techniques for structural reanalysis. These include Taylor series expansions for response variables in terms of design variables and the reduced-basis method. In addition, modifications to these techniques are proposed to overcome some of their major drawbacks. The modifications include a rational approach to the selection of the reduced-basis vectors and the use of Taylor series approximation in an iterative process. For the reduced basis a normalized set of vectors is chosen which consists of the original analyzed design and the first-order sensitivity analysis vectors. The use of the Taylor series approximation as a first (initial) estimate in an iterative process, can lead to significant improvements in accuracy, even with one iteration cycle. Therefore, the range of applicability of the reanalysis technique can be extended. Numerical examples are presented which demonstrate the gain in accuracy obtained by using the proposed modification techniques, for a wide range of variations in the design variables.
    Keywords: STRUCTURAL MECHANICS
    Type: Computers and Structures; 4; Aug. 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 34
    facet.materialart.
    Unknown
    Static, stability, and dynamic analysis of shells of revolution by numerical integration - A comparison (1974)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: Recent innovations in digital computer technology have enabled engineers to analyze shell structures of complex configurations without unduly restrictive approximations. An attempt is made to compare the various programs now generally available from the point of view of the advantages of the relative technique utilized, as well as the programmed state of the art. Many of the comparisons are based on the sample problems solved by the STARS-2 system of programs. These examples indicate both the structural detail which can be analyzed by, and the analytical capabilities available in, the numerical shell-of-revolution programs. All advantages and differences are demonstrated by use of solutions for realistic shell problems in the areas of statics, stability, vibrations, and dynamic response of shells subjected to time-dependent loadings.
    Keywords: STRUCTURAL MECHANICS
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 35
    facet.materialart.
    Unknown
    Forced vibrations of multi-component compliant tanks and feedlines (1974)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: An analytical and experimental research program was performed to investigate the effects of flexible tanks and lines and the total system dynamic response of a simple physical system which had some of the essential features of a liquid-fueled launch vehicle. Several vessel-wall materials were used to obtain a range of elastic moduli. Water was used to simulate the fuel and an electromagnetic shaker provided external excitation such as might originate from a rocket-propulsion system. Experimental data were compared to values obtained from mathematical models for the many degree-of-freedom lumped-mass representation.
    Keywords: STRUCTURAL MECHANICS
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 36
    facet.materialart.
    Unknown
    Nonproportional loading limit for structures (1974)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: The design of most structures involves ensuring integrity for several independent loading conditions. Often, it is rational to design these, exploiting the ductility of the materials to reduce structural costs. Then, ensuring integrity evokes the need for nonmonotonic limit analyses. A groundwork is laid for implementing these analyses. An alternate limit load characterization to that of Greenberg is provided, a mathematical statement of the problem leading to both monotonic (proportional) and nonmonotonic limit loads values is formulated, a direct limit load analysis procedure for analysis within a finite-element framework is described, and limit loads for sets of simple structures are evaluated. A direct limit analysis process is described, and monotonic limit loads are characterized. The process furnishes 'exact' values of limit loads with increasing efficiency as the number of structural elements and force redundancy decreases. Tests show that the accuracy of predicting nonmonotonic limit loads is very sensitive to the number of degrees of freedom in the analysis compared with the total number in the model.
    Keywords: STRUCTURAL MECHANICS
    Type: Computers and Structures; 4; Mar. 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 37
    facet.materialart.
    Unknown
    Adhesive fracture mechanics (1974)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: In studies of fracture mechanics the adhesive fracture energy is regarded as a fundamental property of the adhesive system. It is pointed out that the value of the adhesive fracture energy depends on surface preparation, curing conditions, and absorbed monolayers. A test method reported makes use of a disk whose peripheral part is bonded to a substrate material. Pressure is injected into the unbonded central part of the disk. At a certain critical pressure value adhesive failure can be observed. A numerical stress analysis involving arbitrary geometries is conducted.
    Keywords: STRUCTURAL MECHANICS
    Type: International Journal of Fracture; 10; Mar. 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 38
    facet.materialart.
    Unknown
    The stability of supermassive stars in the Parametrized Post-Newtonian framework (1974)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: The binding energy and stability of supermassive stars (SMS's) are examined in the framework of the Parametrized Post-Newtonian (PPN) formalism of Will and Nordvedt. The PPN formalism encompasses the post-Newtonian limit of virtually every theory of gravity, differentiating between theories by means of nine PPN parameters. A general expression is derived for the energy integral in the PPN framework, and those theories in which the energy will be conserved are defined. In all such theories, a SMS of radius less than a critical radius will be unstable against adiabatic radial perturbations. Present experimental limits on the PPN parameters gamma and beta do not exclude the possibility of the existence of stable, non-rotating, hydrogen-burning SMS's of masses an order of magnitude larger than the upper limit for the mass of such stars predicted in general relativity.
    Keywords: ASTROPHYSICS
    Type: Astrophysics and Space Science; 31; Dec. 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 39
    facet.materialart.
    Unknown
    A comparison of homogeneous stellar models based on the Cox-Stewart and Carson opacities (1974)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; 194; Dec. 15
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 40
    facet.materialart.
    Unknown
    Fine-scale structure of a cold hydrogen layer (1974)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: Neutral-hydrogen absorption-line interferometer observations are reported for five continuum radio sources situated behind an extensive layer of cold interstellar H I gas. In contrast to low-spatial-resolution emission-line observations reported earlier which show the large-scale uniformity of the layer, the high-spatial-resolution absorption-line observations reveal variations in the velocity and density within the layer. The new results together with the old indicate the apparent coexistence of a large-scale mechanism for triggering the formation of cold hydrogen and an instability mechanism leading to small-scale irregularities.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; 194; Dec. 1
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 41
    facet.materialart.
    Unknown
    New triangular plate-bending finite element with transverse shear flexibility (1974)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Keywords: STRUCTURAL MECHANICS
    Type: AIAA Journal; 12; Dec. 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 42
    facet.materialart.
    Unknown
    Degeneracy effects of neutrino mass ejection in supernovae (1974)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: A neutrino mechanism is discussed in order to explain supernovae in massive stars. An argument is presented for supernova mass ejection through leptonic neutrino transport characteristics suppressed by the arbitrary zero chemical potential condition. Results show that lepton conservation effects may be important in supernova neutrino transport. At low temperature and density the diffusion approximation becomes less precise because of the long mean free paths of low energy neutrinos. The amount of equilibrium neutrino spectrum affected here is small over most of the collapsing supernova structure.
    Keywords: ASTROPHYSICS
    Type: Nature; 252; Nov. 22
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 43
    facet.materialart.
    Unknown
    Weak interstellar lines in the visible spectrum of zeta Ophiuchi (1974)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; 193; Oct. 1
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 44
    facet.materialart.
    Unknown
    On the theory of thermal runaway in the hydrogen envelope of a white dwarf (1974)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: An evolutionary sequence was calculated for a white dwarf on which a hydrogen rich envelope is assumed to increase with time. The stellar models were computed by integrating numerically the system of stellar structure equations by means of the Henyey method. The accretion of matter was assumed to be quasi-static. Near the point of the chemical discontinuity, a temperature maximum is shown to arise, and hydrogen ignites; a thin shell energy source is formed which is thermally unstable. The resulting thermal runaway was investigated numerically and by means of a simple approximation based on the energy balance in the hydrogen burning shell source.
    Keywords: ASTROPHYSICS
    Type: Astrometrics and Astrophysics, No. 17 (NASA-TT-F-15768); p 1-55
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 45
    facet.materialart.
    Unknown
    Estimates of the Venus atmosphere optical characteristics with application to the problem of photographing its clouds and surface (1974)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: Optical parameters investigated and solved for included: (1) cloud layer albedo and cloud cover optical thickness; (2) planetary surface self-radiation influence; (3) light flux distribution as function of atmospheric height; (4) upper estimate of the observed contrasts; (5) surface optical parameters; and (6) contrast decrease with altitude.
    Keywords: ASTROPHYSICS
    Type: Space Iconics (NASA-TT-F-798); p 121-135
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 46
    facet.materialart.
    Unknown
    Applicability of the diffusion approximation (1974)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: Several methods using an approximate form of the scattering indicatrix are discussed for simplifying the calculation of radiation transport in planetary atmospheres.
    Keywords: ASTROPHYSICS
    Type: Space Iconics (NASA-TT-F-798); p 75-84
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 47
    facet.materialart.
    Unknown
    Interactive design of large end rings on stiffened conical shells using composites (1974)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: Design study methods and results for a composite reinforced base ring for the conical aeroshell structure of the planetary lander vehicle for Project Viking, an unmanned mission to Mars, are presented. The aeroshell is a ring and stringer-stiffened conical shell structure having a half angle of 70 degrees with a large base ring mounted at the outer edge of the cone and a large pay-load ring in the interior with many smaller rings spaced along the inside shell surface. The purpose of the structure is to develop the aerodynamic drag required to decelerate the lander in the Mars atmosphere to facilitiate a soft landing. The design of a shell structure of this complexity requires the use of the latest technology available in a large general-purpose shell buckling program. The large general-purpose non-linear shell buckling program (BOSOR 2) which was used for this purpose is described.
    Keywords: STRUCTURAL MECHANICS
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 48
    facet.materialart.
    Unknown
    The effect of rotation on the hydrodynamics of stellar collapse (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Keywords: ASTROPHYSICS
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 49
    facet.materialart.
    Unknown
    Fragmentation in rotating isothermal protostellar clouds (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The paper reports results of an extensive set of three-dimensional hydrodynamic calculations performed to investigate the susceptibility of rotating clouds to gravitational fragmentation; only isothermal collapse sequences were considered. It is found that rotating isothermal gas clouds are unstable to fragmentation under a wide range of conditions. The degree of instability and the mode (ring vs. blob) of fragmentation is sensitive to alpha, but insensitive to beta. The initial amplitude of a perturbation does not appear to be crucial; fragmentation should occur eventually even for low-amplitude initial NAPs.
    Keywords: ASTROPHYSICS
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 50
    facet.materialart.
    Unknown
    Spectroscopic and polarimetric observations of NGC 1333 and the surrounding dark cloud complex (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Spectroscopy and polarimetry of several very red stars, noted on Near Infrared Photographic Sky Survey photographs in the region of NGC 1333, have yielded a 'map' suggesting the extent of polarization arising from a two-cloud structure in the region. Spectral types and color indices of the stars make it possible to infer that grain radii in the clouds exceed typical interstellar medium values and, further, that they increase with optical depth into the cloud. The present observations indicate that the cloud structure is far more extensive than previously realized.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal; 85; Dec. 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 51
    facet.materialart.
    Unknown
    Collapse and equilibrium of rotating, adiabatic clouds (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: A numerical hydrodynamics computer code analysis of the collapse and establishment of equilibrium of adiabatic gas clouds restricted to axial symmetry found that the clouds are originally uniform in density and rotation. The method can compare the dynamic collapse and approach to equilibrium with the data on incompressible uniformly rotating equilibrium clouds and on equilibrium structures of differentially rotating polytropes. It is concluded that the stellar formation theory indicates that the low alpha fragments produced at the termination of the dynamic isothermal collapse phase of interstellar clouds may undergo significant dynamic collapse in an adiabatic regime leading to transitory ring formation and additional fragmentation on a smaller scale.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 242
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 52
    facet.materialart.
    Unknown
    Comparisons of interstellar CH/+/ and H2 (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Copernicus observations of H2 toward stars in the Pleiades and 23 Orionis have been obtained because of their importance in understanding the formation of interstellar CH(+). No model of CH(+) equilibrium seems to agree very well with these observations; in particular, the suggestions that CH(+) is formed either from collisions between vibrationally excited H2 and C(+) or from radiative association of C(+) and H2 can apparently be excluded. These data do suggest that there is a correlation between the amounts of rotationally excited H2 and CH(+) which are present. Observations of the Pleiades also help interpretations of the reflection nebulae near these stars.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 242
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 53
    facet.materialart.
    Unknown
    Axial rotation, tangled magnetic fields, and theoretical models of very massive stars (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: A simple method of computing theoretical models of very massive stars endowed with fast axial rotation and tangled magnetic fields is described and used in the present paper. Both of the two perturbing (nongravitational) forces induce changes in the luminosity and radius that are studied as functions of zero-age chemical composition, opacity, and evolutionary state of the interior. The central condensation of the star is found to have a significant influence on shifts of the upper main-sequence band in the H-R diagram if the perturbing force is concentrated in the stellar envelope (but not if the perturbing force is distributed so as to be approximately proportional to gravity everywhere); the layers of the envelope that contribute most heavily to the central condensation lie approximately at a radius fraction of r/R = 0.5. It is shown that fast uniform rotation and intense envelope magnetic fields lead to probably the largest possible shifts of the main-sequence band in the H-R diagram that rotation and magnetic fields can induce. These displacements are, however, too small to account for the total width of the observed main-sequence band at luminosities brighter than log (L/solar luminosity) = 4.5.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 242
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 54
    facet.materialart.
    Unknown
    The evolution of supernova remnants in different galactic environments and its effects on supernova statistics (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: It is shown that only a small fraction of the many supernovae in the Galaxy produces observable supernova remnants; this fraction, which is found to depend weakly on the lower mass limit of the SN progenitors, and more strongly on the specific characteristics of the associated interstellar medium, decreases from about 15% near the galactic center to 10% at R(gal) of about 10 kpc and drops nearly to zero for R(gal) greater than 15 kpc. Whether an SNR is detectable is determined by the density of the ambient interstellar medium in which it is embedded; it is found that SNRs are detectable only above some critical density (about 0.1 per cu cm). The presence of large low-density superbubble cavities around stellar associations due to the combined effects of stellar winds and supernova shells strongly suggests that a large portion of the detectable SNRs must have runaway stars as their progenitors.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 242
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 55
    facet.materialart.
    Unknown
    The unique cosmic event of 1979 March 5 (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The transient gamma-ray burst observed on March 5, 1979 by the nine spacecraft forming the interplanetary gamma-ray burst network is discussed. Measurements reveal the event to be unlike any previously observed gamma-ray burst or X-ray burster, with a maximum intensity greater than several thousandths erg/sq cm per sec, a rise time of less than 200 microsec, a narrow and featureless initial spike and a regular 8-sec oscillation with a compound pulse shape. The source of the transient has been localized to a region including the supernova remnant N 49 in the Large Magellanic Cloud, at a distance of 55 pc, and a ratio of X-ray point-source steady state to transient emission of less than 10 to the -9th was obtained. The identification of the burst source with the supernova remnant at that distance would require an enormous source output if it was radiated isotropically, and substantially less if beaming is present. Alternatively, the event could be explained by a nearby, invisible neutron star.
    Keywords: ASTROPHYSICS
    Type: Comments on Modern Physics; vol. 9
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 56
    facet.materialart.
    Unknown
    On the phase-locked polarization variations in Cygnus X-1 (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The paper presents data on the accumulated V-band orbital phase curves of polarization in Cygnus X-1 which disagree with the analysis of Simmons, Aspin, and Brown (1980). No curves which conform to the canonical model were observed, and a noncanonical structure is indicated by F tests on third, fourth, and fifth harmonics, which have a probability of 0.85 as a group. The fifth harmonic has a probability of 0.99; in contrast, the fundamental harmonic has a probability of only 0.6, which is below the detection threshold. Therefore, major conclusions of Simmons et al based on a nonsymmetrical canonical model assuming that fundamental harmonics are present, but harmonics with n greater than 2 are absent, are unacceptable. Analysis of the author's data by Simmons et al is criticized on the grounds that he did not take into account the cumulative aspects of the data and did not recognize the need to average out the random noise generated by Cygnus X-1 over many orbital cycles.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics; 91; 1-2,; Nov. 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 57
    facet.materialart.
    Unknown
    The X-ray structure of two rich galaxy clusters and its implications for the detectability of microwave diminutions (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The X-ray observations of the galaxy clusters Abell 2319 and 576 show a reduced temperature of the microwave background due to the Suniaev-Zeldovich effect. The X-ray maps indicate smooth emission in these clusters concentrated toward the optical center; the surface brightness in the 1-3 keV band falls with the inverse square of radius outside a small core, and fits the Hubble's law of optical surface brightness of elliptical galaxies. The low temperature indicates that in A576 (1) the core radius of the gravitational potential is two to three times larger than inferred from galaxy counts, (2) the temperature rises with radius over most of the cluster and falls to zero at large radii, and (3) the gas does not obey the equation of state.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 241
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 58
    facet.materialart.
    Unknown
    Measurements of mixed-mode crack surface displacements and comparison with theory (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The problem of a finite-width tension specimen containing a crack oriented at various angles to the load axis is attacked from experimental and theoretical viewpoints. Displacements of an electro-machined slot, 12.5 mm long and oriented at angles of 0, 15, 30, 45, 60, and 75 deg, are measured using a laser-based in-plane measuring technique. Various width specimens, ranging from a crack-length/width ratio of 0.167 to 0.794, are tested. A boundary-integral equation method is extended to deal with the presence of a sharp crack. Agreement between the two approaches is generally good except near the tips of the cracks.
    Keywords: STRUCTURAL MECHANICS
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 59
    facet.materialart.
    Unknown
    Radial accretion of H-rich material onto a He white dwarf (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The nova outburst is modeled by spherically accreting H-rich material onto a 1 solar mass He white dwarf at a rate of 10 to the -8th solar mass/yr. The star accretes for 5848 years, when the nuclear reactions run away near the base of the accreted envelope. The nuclear-energy generation rate rises to 4.6(8) solar luminosities, and the envelope expands in response to it. However, nova-like mass ejection does not occur because the envelope is of insufficient mass, the base of the envelope is only mildly electron degenerate, and there is no enrichment of the CNO abundance. To overcome these limiting conditions, it is suggested that the H-rich material be accreted either more slowly than 10 to the -10th solar mass/yr or with angular momentum. Outbursts resulting in the former case should be similar to the nova models computed by Starrfield, Truran, and Sparks. Outbursts in the latter case should be strengthened, and novae might result because the H-rich material will be mixed into the surface layers of the white dwarf, as first suggested by Kippenhahn and Thomas (1978).
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 239
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 60
    facet.materialart.
    Unknown
    Spontaneous formation of knots in relativistic flows - A model for variability in compact synchrotron sources (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: A model is proposed in which regions of enhanced synchrotron emission are formed via radiative thermal instabilities in relativistic flows. A perturbed volume in which the magnetic field is enhanced by a few tens of a percent relative to the steady value collapses due to the increased cooling rate and consequent loss in pressure. The collapse further increases the magnetic field, leading to even shorter radiative lifetimes. The instability progresses in this way until either the external electron pressure is balanced by the perturbed magnetic pressure or the overall expansion of the flow becomes important. A fluid-dynamical treatment of the instability is performed, and the results are shown to apply to flux variations and formation of knots in the relativistic flows which are thought to occur in quasars and active galactic nuclei. The knots possess the same kinematic properties as the collimated flow and can thus be responsible for the apparent superluminal motions observed in compact radio sources.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 239
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 61
    facet.materialart.
    Unknown
    Binary model of Circinus X-1. I - Eccentricity from combined X-ray and radio observations (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: A binary star model is used to account for the 16.59-d flaring behavior of the X-ray emission from Circinus X-1. The orbital eccentricity of 0.8 + or - 0.1 is derived from the X-ray light curve by assuming that the sharp X-ray cut-off every 16.59-d is a result of bound-free absorption in the primary star's stellar wind. The shape of the light curve has changed over the last eight years, and this is interpreted as due to orbital precession of the binary system. Simultaneous radio and X-ray observations of the flare from Circinus X-1 on February 1-5, 1978 are reported. These are accounted for within the framework of the model. The radio observations at 5 GHz are used independently to derive a high value of the orbital eccentricity (e = 0.7).
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics; 86; 3, Ju; July 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 62
    facet.materialart.
    Unknown
    Green's function for a crack emanating from a circular hole in an infinite sheet (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Stress-intensity factors, K/I/ and K/II/, are obtained for a point loaded crack emanating from a circular hole in an infinite plate. A series approach and the Muskhelishvili formulation in the two-dimensional theory of elasticity are used to derive the solution. The applicability of the solution is demonstrated by using it as a Green's function to obtain K/I/ and K/II/ and the case of (1) biaxial tension of an infinite plate and (2) bending of a wide strip.
    Keywords: STRUCTURAL MECHANICS
    Type: International Journal of Fracture; 16; Aug. 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 63
    facet.materialart.
    Unknown
    Response of a panel to a supersonic turbulent boundary layer - Studies on a theoretical model (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: A study of the response of a clamped panel to a supersonic turbulent boundary layer, based on a recently developed theoretical model, is presented. It is demonstrated that the model incorporates the effect of coupling between the panel motion and the flow of the surrounding fluid. Further, a Ritz-Galerkin method is used to obtain approximate solutions for the statistics of the panel response to the turbulence. The numerical results are compared with previous experimental data and the theoretical model is assessed.
    Keywords: STRUCTURAL MECHANICS
    Type: Journal of Sound and Vibration; 71; July 22
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 64
    facet.materialart.
    Unknown
    IUE observations of the atmospheric eclipsing binary system Zeta Aurigae (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: IUE observations of the eclipsing binary system Zeta Aurigae made prior to and during the eclipse of the relatively small B8 V star by the cool supergiant star (spectral type K2 II) are reported. Spectral lines produced by the absorption of B star radiation in the atmosphere of the K star during eclipse can be used as a probe of the extended K star atmosphere, due to the negligible cool star continuum in the 1200-3200 A region. Spectra taken prior to eclipse are found to be similar to those of the single B8 V star 64 Ori, with the exception of very strong multi-component absorption lines of Si II, Si IV, C IV and the Mg resonance doublet with strong P Cygni profiles, indicating a double shell. Absorption lines including those corresponding to Al II, Al III, Cr II, Mn II, Fe II, Ni II and Ca II are observed to increase in strength and number as the eclipse progresses, with high-ionization-potential lines formed far from the K star, possibly in a shock wave, and low-ionization potential lines, formed in cool plasma, probably a cool wind, nearer to the K star. Finally, an emission-line spectra with lines corresponding to those previously observed in absorption is noted at the time the B-star continuum had disappeared.
    Keywords: ASTROPHYSICS
    Type: Nature; 286; Aug. 7
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 65
    facet.materialart.
    Unknown
    Vibration and buckling of rectangular plates under in-plane hydrostatic loading (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Numerical solutions are presented for the fundamental natural frequency and mode shape of a rectangular plate loaded by in-plane hydrostatic forces for a wide variety of aspect ratios, boundary conditions, and load magnitudes. All six possible combinations of simply supported and clamped edges are considered. The limiting conditions of unloaded vibration and buckling are discussed in detail, with emphasis on the preferred mode shape. Design curves and approximate formulae are presented which provide a simple means of determining the fundamental frequency parameter.
    Keywords: STRUCTURAL MECHANICS
    Type: Journal of Sound and Vibration; 70; June 22
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 66
    facet.materialart.
    Unknown
    The high-energy X-ray spectrum of Scorpius X-1 (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 238
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 67
    facet.materialart.
    Unknown
    Quasi-stellar objects in the intergalactic medium - Source for the cosmic X-ray background (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Current estimates of QSO luminosity, number density, evolution, and spectral index are used to study whether the diffuse cosmic ray background is (1) entirely due to thermal bremmstrahlung of the intergalactic medium (IGM), (2) completely supplied by QSO X-rays, or (3) a combination of both. The upper limits on an IGM fractional density with respect to closure are Omega = 0.26, 0.24, and 0.21 for pure collisional, photo/collisional, and pure photoionization, respectively. These calculations give emission spectra, Compton distortion of the microwave background, and optical depths to distant QSOs for comparison with relevant data.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 238
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 68
    facet.materialart.
    Unknown
    A model of comet comae. II - Effects of solar photodissociative ionization (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Improvements to a computer model of coma photochemistry are described. These include an expansion of the chemical reactions network and new rate constants that have been measured only recently. Photolytic reactions of additional molecules are incorporated, and photolytic branching ratios are treated in far greater detail than previously. A total of 25 photodissociative ionization (PDI) reactions are now considered (as compared to only 3 PDI reactions previously). Solar PDI of the mother molecule CO2 is shown to compete effectively with photoionization of CO in the production of observed CO(+). The CO(+) density peak predicted by the improved model, for CO2 or CO mother molecules, is deep in the inner coma, in better agreement with observation than the old CO2 model. However, neither CO2 nor CO mother molecule calculations reproduce the CO(+)/H2O(+) ratio observed in comet Kohoutek. PDI products of CO2, CO, CH4, and NH3 mother molecules fuel a complex chemistry scheme, producing inner coma abundances of CN, C2, and C3 much greater than previously calculated.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 238
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 69
    facet.materialart.
    Unknown
    Laser spectroscopy of the CN radical and astrophysical applications (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The formation of CN radicals by flash photolysis of a number of parent molecules was monitored by laser induced fluorescence in the B2Sigma(plus)-X2Sigma(plus) transition of CN. The rotational and vibrational energy of the newly formed radicals in the X state was measured directly. Formation of CN(A2Pi) in the lower vibrational levels was determined by an indirect method based on resonant energy transfer to higher vibrational levels of the ground state. These laboratory studies have shown that high initial internal excitation of CN with rotational levels of maximum N equals 50-70 is the rule. In general, the formation of simple molecules in excited states is commonly the case. There appear to be astrophysical systems where radiation from these excited levels may be detectable. Such observations would serve as a probe of molecular formation.
    Keywords: ASTROPHYSICS
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 70
    facet.materialart.
    Unknown
    The spectrum of IRC + 10216 from 2.0 to 8.5 microns (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Low-resolution spectra of IRC + 10216 have been obtained from 2 to 8.5 microns from NASA's Kuiper Airborne Observatory at an altitude of 12.5 km (41,000 feet). Observations were made during 1976 January and 1977 February. In both sets of data, the spectral flux reaches its maximum between 6.0 and 6.6 microns and the previously reported 3.1-micron feature is observed; no obvious new absorption features have been found. The new data together with other spectral data and measurements of the spatial extent of IRC + 10216 impose conditions that must be met by models of the continuum. Several simple models for 2-8.5 micron radiation are examined. The new continuum data impose a constraint on the size of the grains in the cooler, optically thin part of the object. Earlier photometry has been combined with the present data to yield an improved value of the average period: 644 + or - 17 days. It appears that the variability is irregular and that the minima have been deeper in recent years than they were in 1965-1969.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 238
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 71
    facet.materialart.
    Unknown
    Self-gravitating gas flow in barred spiral galaxies (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: A series of two-dimensional numerical experiments is performed in order to test the response of an isothermal, self-gravitating gas disk to a uniformly rotating, barlike gravitational potential. The barlike potential is an equilibrium stellar model from the n-body calculations of Miller and Smith (1979). In the bar-dominated, central regions of the disk, a gas bar whose phase depends primarily on the location of principal resonances in the disk is formed. This response can be understood in terms of orbit-crowding effects. In the gas-dominated outer regions of the disk, two-armed trailing spiral waves are formed. The local pitch angle of these waves increases with increasing fractional gas mass. These self-gravitating gas waves are not self-sustaining. They are driven from the ends of equilibrium stellar bars, and their phase does not depend on the location of resonances in the disk. The relevance of these self-gravitating waves to observations and models of barred spiral galaxies is discussed. It is concluded that these waves and their associated ringlike structures may be consistent with the morphological distribution of gas features in barred spiral galaxies.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 238
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 72
    facet.materialart.
    Unknown
    Optical surface brightnesses of dusty galaxies (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: It is suggested that Freeman's (1970) result that the disk portions of spiral galaxies have a preferred central surface brightness might be the consequence of observing optically thick ensembles of a standard mix of stars and dust. Regardless of whether this hypothesis is correct, the observation that elliptical galaxies usually have central surface brightnesses considerably greater than the disk portions of spirals can be understood if there is much less dust within the elliptical systems. In particular, ellipticals probably have dust-to-total-mass ratios at least a factor of 100 smaller than in the disk portions of spirals, although there is no evidence that the dust-to-interstellar-gas ratios are different. When stars were forming within ellipticals, these galaxies were probably dustier than they are now, and their visible light output could have been substantially affected. It will probably be necessary to establish the dust content of galaxies as a function of redshift to use these objects as cosmological probes.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 238
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 73
    facet.materialart.
    Unknown
    New spectroscopic constants for methane derived by using microwave transitions from the interstellar medium (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Keywords: ASTROPHYSICS
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 74
    facet.materialart.
    Unknown
    Comment on the paper 'A cosmological limit on the possible variation of G' (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Keywords: ASTROPHYSICS
    Type: Royal Astronomical Society; vol. 191
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 75
    facet.materialart.
    Unknown
    HEAO A-2 observations of the X-ray spectra of the Centaurus and A1060 clusters of galaxies (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: X-ray spectral observations of two nearby low-luminosity clusters of galaxies are presented. For the Centaurus cluster an emission feature at 7.9 keV is detected at about one-third of the strength of the 6.7 keV line. This higher energy line represents K-beta emission from highly ionized iron. In addition, it is demonstrated that for neither the Centaurus nor the A1060 cluster can an isothermal model with an Fe emission line adequately fit the data. Instead, the simplest models which provide acceptable fits include a second, harder component which may be either a second exponential or a power law. The implications of the two-component nature of the continuum on the Fe abundance and the X-ray surface-brightness distribution are discussed.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 236
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 76
    facet.materialart.
    Unknown
    Observation and search for gamma rays 1-20 MeV from the Crab, NGC 4151, Cyg X-1, Cyg X-3, CG 135+1 and 3C 273 (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Observations and limiting values for the flux of 1-20 MeV gamma rays from the Crab, the Seyfert galaxy NGC 4151, the black hole candidate Cyg X-1, Cyg X-3 and the two nearest quasars CG 135+1 and 3C 273 are reported. Measurements of the energy and scatter angle of gamma rays at zenith angles between 10 and 30 deg were obtained by a balloon-borne double-scatter gamma-ray telescope. The flux from the Crab from 1.2 to 10 MeV is found to be 0.0039 + or - 0.0020 photons/sq cm per sec, and the energy distribution of the flux from 1.2 to 20 MeV is determined. Two-standard-deviation upper limits to the gamma-ray flux in the intervals 1.2-3, 3-5, 5-10 and 10-20 MeV of 0.0003, 0.0002, 0.00006 and 0.00004 photons/sq cm/sec are found for NGC 4151, Cyg X-1 and Cyg X-3, while those of 0.0005, 0.0003, 0.0001 and 0.00004 photons/sq cm per sec are determined for both quasars. These upper limits are interpreted as restricting confirmed gamma-ray sources to the Crab and NP 0532, and as evidence against Seyfert galaxies as the source of cosmic diffuse radiation.
    Keywords: ASTROPHYSICS
    Type: Nature; 284; Apr. 17
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 77
    facet.materialart.
    Unknown
    Simultaneous X-ray and optical observations of rapid variability in Scorpius X-1 (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Copernicus and SAS-3 observations of Sco X-1 during very active states show strong and rapid X-ray flickering with time scales as short as 20 sec. Simultaneous optical photometry reveals similar and remarkably well correlated flickering of lower amplitude. The level of correlation decreases when the X-ray source becomes fainter, but optical and X-ray fluxes, averaged over 1 min, are usually well correlated for B magnitudes less than 12.9. Cross-correlation analysis of the data during periods of high activity shows no really significant time delay between X-ray and optical features, although the cross-correlation function peaks systematically for positive lag values (optical following X-rays). The amplitude of the X-ray flickering exhibits a strong energy-dependence consistent with the well-known intensity versus spectral-hardness relation derived from previous observations. The highly correlated optical activity is interpreted as due to reprocessing of X-ray photons in the binary system.
    Keywords: ASTROPHYSICS
    Type: Royal Astronomical Society; vol. 191
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 78
    facet.materialart.
    Unknown
    Mass loss from UW Canis Majoris (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The present analysis is an application of the theory described by Lucy (1971) for the calculation of P Cygni resonance line profiles formed by isotropic and coherent scattering in spherically symmetric expanding circumstellar envelopes. Copernicus satellite measurements of resonance features in the FUV spectrum of the O 7 supergiant UW Canis Majoris (= HD 57060) are compared with theoretical P Cygni profiles. Grids of line profiles are computed using four free parameters which contain information about the velocity law, ionization equilibrium, temperature, and envelope density. Thus, with the assumption of a spherically symmetric steady flow, and of solar element abundances, the stellar mass loss rate and the electron temperature of the expanding shell can be derived. The mass flow is treated in a fully transonic way, i.e., the Sobolev approximation is applied.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics; 83; 3, Ma; Mar. 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 79
    facet.materialart.
    Unknown
    IUE observations of the hot components in two symbiotic stars (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Recent IUE observations reveal striking differences in the UV spectra of two symbiotic stars, R Aqr and RW Hya. RW Hya is found to be an unexpectedly intense source of UV radiation. The measurements reported demonstrate the presence of a hot component in each star, supporting the view that each is a binary system with a luminous red primary and a hot, subluminous companion. In one case, the hot companion manifests itself by exciting a compact nebulosity; in the other case the continuous spectrum of the hot star is directly detected, while the continuum of nebulosity excited by the hot star is detected at longer wavelengths.
    Keywords: ASTROPHYSICS
    Type: Nature; 284; Mar. 13
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 80
    facet.materialart.
    Unknown
    Collapsing cloud models for Bok globules (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The dynamic collapse of rotating gas clouds is calculated for a wide range of initial conditions. Properties of cloud models are compared with observed radio and optical properties of Bok globules, to test the hypothesis that globules undergo collapse and to determine parameters which are not easily observed. Five of the six globules studied are consistent with collapse models. It is inferred that these objects have masses of about 100 solar masses and ages smaller than their free-fall times. Inferred initial densities are much larger than minimum densities for gravitational collapse, suggesting that collapse is initiated by strong external compression or that globules are fragments of larger condensed clouds. Values inferred for the (C-13)O/H2 ratio are smaller than previous estimates and depend strongly on cloud density.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 236
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 81
    facet.materialart.
    Unknown
    Cosmological tests of the Hoyle-Narlikar conformal gravity (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: For the first time the Hoyle-Narlikar theory with creation of matter and a variable gravitational constant G, is subjected to the following cosmological tests: (1) the magnitude versus z relation, (2) the N(m) versus m relation for quasars, (3) the metric angular diameters versus z relation, (4) the isophotal angles versus z relation, (5) the log N-log S radio source count, and finally (6) the 3 K radiation. It is shown that the theory passes all these tests just as well as the standard cosmology, with the additional advantage that the geometry of the universe is uniquely determined, with a curvature parameter equal to zero. It is also interesting to note that the variability of G affects the log N-log S curve in a way similar to the density evolution introduced in standard cosmologies. The agreement with the data is therefore achieved without recourse to an ad hoc density evolution.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 236
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 82
    facet.materialart.
    Unknown
    Radial distribution of forbidden Fe X and forbidden Fe XIV emission in the Cygnus Loop. II (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 235
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 83
    facet.materialart.
    Unknown
    On C4H versus vibrationally excited CO in IRC + 10216 (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The identification of the 114,221-MHz line in the spectrum of the evolved carbon star IRC +10216 with a blend of the rotational transition of C4H and the first rotational transition of vibrationally excited CO is investigated. A spectrum of the source was obtained using an 11-m telescope in the range covering the N = 12 to 11 and 11 to 10 spin-doublet rotational transitions of C4H. Two peaks of equal intensity and width are found in each band, suggesting a spin rotation constant of 1.06 for the 12 to 11 doublet and 1.09 for the 11 to 10 doublet, and excluding the possibility that vibrationally excited CO made any contribution to the 12 to 11 doublet. An additional survey of the regions from 103.8 to 107.5 and 113.3 to 117.0 GHz has revealed no new lines stronger than 0.1 K in the spectrum of IRC +10216.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 235
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 84
    facet.materialart.
    Unknown
    Case for an open universe (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The determination of the geometrical structure of the universe through the magnitude-vs-redshift relation in standard cosmology has not been very successful, mainly because of the intrinsic insensitivity of the m-vs-z relation to a deceleration parameter, which determines the spatial curvature and therefore the geometry. By relaxing the assumption usually made, i.e., the identity of gravitational and atomic clocks, sufficient sensitivity is achieved. Existing observational evidence then leads one to conclude that the universe is open.
    Keywords: ASTROPHYSICS
    Type: Physical Review Letters; 44; Mar. 17
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 85
    facet.materialart.
    Unknown
    Black holes, quasars, and the universe /2nd edition/ (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Topics of astronomy are discussed in terms of black holes, galaxies, quasars, and models of the universe. Black holes are approached through consideration of stellar evolution, white dwarfs, supernovae, neutron stars, pulsars, the event horizon, Cygnus X-1, white holes, and worm holes. Attention is also given to radio waves from high speed electrons, the radiation emitted by quasars, active galaxies, galactic energy sources, and interpretations of the redshift. Finally, the life cycle of the universe is deliberated, along with the cosmic time scale, evidence for the Big Bang, and the future of the universe.
    Keywords: ASTROPHYSICS
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 86
    facet.materialart.
    Unknown
    Turbulence and the stability of molecular clouds (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Molecular clouds may be stabilized against gravitational collapse by the turbulent velocity field within them. It is suggested that the energy derived from differential galactic rotation can maintain the turbulent flow in the interstellar medium. The characteristic decay time for interstellar turbulence is found to be about 10-billion years. The rate and efficiency of star formation in giant molecular clouds reflect the stochastic nature of turbulence.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 242
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 87
    facet.materialart.
    Unknown
    An assessment of buffer strips for improving damage tolerance of composite laminates (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Graphite/epoxy panels with buffer strips were tested in tension to measure their residual strength with crack-like damage. Panels were made with (45/0/-45/90)2S and (45/0/-45/0)2S layups. The buffer strips were parallel to the loading direction. They were made by replacing narrow strips of the 0 deg graphite plies with strips of either 0 deg S-Glass/epoxy or Kevlar-90/epoxy on either a one-for-one or a two-for-one basis. In a third case, 0 deg graphite/epoxy was used as the buffer material and thin, perforated Mylar strips were placed between the 0 deg plies and the cross-plies to weaken the interfaces and thus to isolate the 0 deg plies. Some panels were made with buffer strips of different width and spacings. The buffer strips arrested the cracks and increased the residual strengths significantly over those of plain laminates without buffer strips. A shear-lag type stress analysis correctly predicted the effects of layup, buffer material, buffer strip width and spacing, and the number of plies of buffer material
    Keywords: STRUCTURAL MECHANICS
    Type: Journal of Composite Materials Supplement; 14; 1, 19; 1980
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 88
    facet.materialart.
    Unknown
    Development and evaluation of two non-linear shell elements (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Two plate and shell displacement elements are developed for use in large deflection non-linear analysis. The elements are of the 'stability' type, in which non-linear strains are included, with their values optimized by added higher order membrane functions and special types of elemental level constraints. The paper summarizes formulation and computational procedures, and discusses numerical results in detail. Conclusions are given regarding the effectiveness of the elements for solving both linear and non-linear shell analysis problems.
    Keywords: STRUCTURAL MECHANICS
    Type: International Journal for Numerical Methods in Engineering; 16; Oct. 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 89
    facet.materialart.
    Unknown
    A wave model for dwarf novae (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The rapid coherent oscillation during a dwarf nova outburst is attributed to an accretion-driven wave going around the white dwarf component of the binary system. The increase and decrease in the period of this oscillation is due to the change in the velocity of the wave as it is first being driven and then damped. Qualitatively, a large number of observations can be explained with such a model. The beginnings of a mathematical representation of this model are developed.
    Keywords: ASTROPHYSICS
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 90
    facet.materialart.
    Unknown
    Collapse, equilibrium, and fragmentation of rotating, adiabatic clouds (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Numerical calculations of the collapse of adiabatic clouds from uniform density and rotation initial conditions show that when restricted to axisymmetry, the clouds form either near-equilibrium spheroids or rings. Rings form in the collapse of low thermal energy clouds and have a ratio of rotational kinetic energy to the absolute value of gravitational potential energy greater than approximately 0.43. When the axisymmetric constraint is removed and an initial m = 2 density variation is introduced, clouds either collapse to form near-equilibrium ellipsoids or else fragment into binary systems through a bar phase. Ellipsoids form in the collapse of high thermal energy clouds and have a rotational kinetic energy/absolute value of gravitational potential energy ratio less than approximately 0.27. The results are consistent with the critical values of the rotational kinetic energy/absolute value of gravitational potential energy ratio for instabilities in Maclaurin spheroids, and suggest that protostellar clouds may undergo a dynamic fragmentation in the nonisothermal collapse regime.
    Keywords: ASTROPHYSICS
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 91
    facet.materialart.
    Unknown
    X-ray line emission from the supernova remnant G292.0 + 1.8 (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The Solid State Spectrometer on the Einstein Observatory has detected line emission from Mg, Si and S in the thermal X-ray spectrum of the supernova remnant G292.0 + 1.8. An over-abundance of sulfur and a probable under-abundance of iron relative to their solar values is indicated by the data. The X-ray and optical data for this object support an interpretation of emission originating in ejecta from the comparatively recent explosion of a massive (about 20-solar-mass) progenitor star.
    Keywords: ASTROPHYSICS
    Type: Royal Astronomical Society; vol. 193
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 92
    facet.materialart.
    Unknown
    A survey of chromospheric Ca II H and K emission in field stars of the solar neighborhood (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Fluxes in 1 A bands at the centers of the H and K lines are being measured in main-sequence F-G-K-M stars in the northern half of the Woolley et al. (1970) 'Catalog of stars within twenty-five parsecs of the sun', in a survey not yet completed. Results for 486 stars are presented in the form of flux-color diagrams and discussed in light of evidence that chromospheric activity declines with age in main-sequence stars. Support is noted for the reality of the Sirius moving group. The relative numbers of more-active (Hyades-like) and less-active (solar-like) F-G stars are tolerably in agreement with a nearly constant rate of formation, but there exists an apparent deficiency in the number of F-G stars exhibiting intermediate activity. The possibility that the gap is an accidental characteristic of the sample will be investigated by extending the survey to southern declinations and greater distances.
    Keywords: ASTROPHYSICS
    Type: Astronomical Society of the Pacific; vol. 92
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 93
    facet.materialart.
    Unknown
    The X-ray pulsars 4U 1145-61 and 1E 1145.1-6141 (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Observations of the neighboring X-ray pulsars 4U 1145-61 and 1E 1145.1-6141 obtained by OSO 8, HEAO 1 and the Einstein Observatory between 1975 and 1979 are reported. A temporal analysis of Einstein Solid State Spectrometer and Monitor Proportional Counter data, OSO 8 A and C detector data and HEAO 1 A-2(3) experiment data confirms the presence of two periodicites at 291 and 297 sec in the region, with the shorter period located within 3 arcmin of 4U 1145-61. Observations indicate the spectrum of 4U 1145-61 to obey a power law with an index of 1.5 out to at least 60 keV, with little variation with pulse phase, and a 500-eV EW iron line at 6.7 keV. The spectrum of the other source is found to be more absorbed. Similarities between the pulsars are noted, and it is suggested that they may be the result of pulsar formation in a homogeneous cloud of progenitors.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 239
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 94
    facet.materialart.
    Unknown
    Observations of Cygnus X-3 with the Einstein /HEAO 2/ X-ray Observatory The period derivative and the asymmetric X-ray light curve (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Cygnus X-3 was observed by the Monitor Proportional Counter on the Einstein (HEAO 2) X-ray Observatory for 2.4 days in 1978 December. The analysis of the data from these observations is used in conjunction with a self-consistent re-examination of previous results from the Uhuru, ANS, COS B, and SAS 3 satellites to investigate earlier reports that the 4.8 hour period of Cygnus X-3 is increasing. It is found that there is indeed a period derivative, P = (1.78 plus or minus 0.40) x 10 to the -9th s/s, which confirms the principal conclusion of previous authors. The possibility that the X-ray source is in an elliptical orbit and that some, or all, of the observed period derivative may be due to apsidal motion is discussed. The elliptic orbit hypothesis explains the observed asymmetry in the average X-ray light curve and leads to the conclusion that the most likely companion to the X-ray source is a helium star, possibly with a light hydrogen envelope
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 239
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 95
    facet.materialart.
    Unknown
    An observational H-R diagram for early-type stars (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: An observational H-R diagram for the O and B stars is discussed and compared with the predicted positions of massive model stars for the case of no mass loss and the case of mass loss. It is shown that the flux effective temperatures of O and B supergiants and of early O stars are less than the effective temperatures which might be inferred from the relative intensities of lines from two stages of ionization of an element.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 239
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 96
    facet.materialart.
    Unknown
    X-ray observations of the Seyfert 1 galaxies AKN 120 and MCG 8-11-11 (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: A new X-ray source, H0523-00, with the optically variable Seyfert 1 galaxy AKN 120 is identified. The source has a 2-10 keV X-ray flux of 2 x 10 to the -11th ergs/sq cm s which corresponds to a 2-10 keV X-ray luminosity of 10 to the 44th ergs/s. X-ray observations over a 1.5 year time span combined with contemporaneous optical photometry show a decrease in the optical with no corresponding decrease in the X-ray. In contrast, similar observations of MCG 8-11-11 show a contemporaneous decrease in optical and X-ray fluxes. It is noted that the infrared and X-ray spectral slopes for these two objects are similar, with the optical being steeper by roughly one unit.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 239
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 97
    facet.materialart.
    Unknown
    The detection of a companion star to the Cepheid variable Eta Aquilae (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Ultraviolet spectra have been obtained with IUE of the classical Cepheid Eta Aquilae at several phases in the 7.18 day period. Significant ultraviolet emission is detected at wavelengths less than 1600 A, where little flux is expected from classical Cepheids. Furthermore, the emission at wavelengths less than about 1600 A does not vary with phase. Comparison with model atmosphere flux distributions shows that the nonvariable emission is consistent with the flux expected from a main-sequence companion star with an effective temperature of about 9500 K (A0 V). The observed ultraviolet flux and spectral type are used to compute a distance of 300 pc to the system, in agreement with the distance predicted using the period luminosity relation.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 238
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 98
    facet.materialart.
    Unknown
    Mode I fracture behavior of nonlinear materials (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: A finite element analysis is presented for the Mode I fracture behavior of cracked plates (stationary crack) made of different nonlinear materials (elastoplastic or elastic locking). The assumed stress-strain behavior of the nonlinear materials was piecewise linear. For each given 'stationary' crack size, the corresponding critical remote tensile stress was calculated based on the maximum crack-tip stress failure criterion. It was found that in the log-log plots of the critical remote stress versus critical crack length, the fracture data of the piecewise linear materials obey a 'stepwise-linear-inverse-square-root' fracture law. It is also shown how the fracture data of the piecewise linear materials can be fitted by proper piecewise graphical shifting of the classical 'inverse-square-root' fracture curve for the linearly elastic materials.
    Keywords: STRUCTURAL MECHANICS
    Type: International Journal of Fracture; 16; June 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 99
    facet.materialart.
    Unknown
    On the time variability of Circinus X-1 - A comparison with Cygnus X-1 (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The time variability and spectral characteristics obtained from Uhuru observations of Cir X-1 (4U 1515-56) are compared with observations of Cyg X-1 (4U 1956+35). It is found that Cir X-1 has a more variable spectrum (with perhaps a state over the 4 days spanned by the data), is less 'noisy', and has correlated fluctuations (as evidenced by the nonzero cross-correlation function between two energy bands) of shorter duration than those present in the shot noise of Cyg X-1.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 236
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 100
    facet.materialart.
    Unknown
    X-rays from RS Canum Venaticorum systems - A HEAO 1 survey and the development of a coronal model (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The paper presents HEAO 1 low-energy X-ray observations of 59 known or suspected RS CVn systems cited in the lists of Hall (1976), Eggen (1978), and the circulars of the Working Group on RS CVn systems of IAU Commission 42. The data are used to argue against the validity of the minimum flux coronal models. A coronal loop model is used to derive expressions for the loop parameters in terms of observable quantities, and find acceptable solutions for RS CVn systems. It is concluded that the difference between solar activity and that observed in RS CVn systems may be merely a matter of scale.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 236
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...