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  • Articles  (5,492)
  • Other Sources  (1,677)
  • Inorganic Chemistry  (5,492)
  • STRUCTURAL MECHANICS  (1,511)
  • ASTROPHYSICS
  • Fisheries
  • Humans
  • 1970-1974  (5,541)
  • 1950-1954  (1,628)
Collection
  • Articles  (5,492)
  • Other Sources  (1,677)
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Year
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  • 1
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    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
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  • 2
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    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
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  • 3
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    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
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  • 4
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    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
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  • 5
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    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
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  • 6
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    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
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  • 7
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    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
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  • 8
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    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
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  • 9
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    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
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  • 10
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    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
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  • 11
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    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
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  • 12
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    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
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  • 13
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    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
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  • 14
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    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
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  • 15
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    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
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  • 16
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    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
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  • 17
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    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
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  • 18
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    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
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  • 19
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    Neutron stars with main sequence binary companions as low luminosity X-ray sources (1974)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics; 37; 1, De; Dec. 197
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  • 20
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    The interaction of interstellar gas with stellar density wave packets (1974)
    In:  Other Sources
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    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
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  • 21
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    The Apsidal-motion test for models of main-sequence stars (1974)
    In:  Other Sources
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    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
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  • 22
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    Main sequence models for massive zero-metal stars (1974)
    In:  Other Sources
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    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
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  • 23
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    Interplanetary sector structure - 1970-1972 (1974)
    In:  Other Sources
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    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
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  • 24
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    Distinctive patterns on the surface of slowly rotating stars whose oscillations are nonlinearly coupled (1974)
    In:  Other Sources
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    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
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  • 25
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    Inclusion of transverse shear deformation in finite element displacement formulations (1974)
    In:  Other Sources
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    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
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  • 26
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    The ethynyl radical C2H - A new interstellar molecule (1974)
    In:  Other Sources
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    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
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  • 27
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    Influence of opacity on the pulsational stability of massive stars with uniform chemical composition. II - Modified Kramers opacity (1974)
    In:  Other Sources
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    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
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  • 28
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    Equation of state at ultrahigh densities. I (1974)
    In:  Other Sources
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    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.
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  • 29
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    Cometary coma ions (1974)
    In:  Other Sources
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    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
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  • 30
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    An empirical line-blanketing study of Am stars (1974)
    In:  Other Sources
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    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
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  • 31
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    Li production in alpha-alpha reactions (1974)
    In:  Other Sources
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    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
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  • 32
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    Microcraters formed in glass by projectiles of various densities (1974)
    In:  Other Sources
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    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
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  • 33
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    Approximate techniques of structural reanalysis (1974)
    In:  Other Sources
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    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
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  • 34
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    Static, stability, and dynamic analysis of shells of revolution by numerical integration - A comparison (1974)
    In:  Other Sources
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    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
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  • 35
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    Forced vibrations of multi-component compliant tanks and feedlines (1974)
    In:  Other Sources
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    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.
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  • 36
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    Nonproportional loading limit for structures (1974)
    In:  Other Sources
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    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
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  • 37
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    Adhesive fracture mechanics (1974)
    In:  Other Sources
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    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
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  • 38
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    The stability of supermassive stars in the Parametrized Post-Newtonian framework (1974)
    In:  Other Sources
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    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
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  • 39
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    A comparison of homogeneous stellar models based on the Cox-Stewart and Carson opacities (1974)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; 194; Dec. 15
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  • 40
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    Fine-scale structure of a cold hydrogen layer (1974)
    In:  Other Sources
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    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
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  • 41
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    New triangular plate-bending finite element with transverse shear flexibility (1974)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Keywords: STRUCTURAL MECHANICS
    Type: AIAA Journal; 12; Dec. 197
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  • 42
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    Degeneracy effects of neutrino mass ejection in supernovae (1974)
    In:  Other Sources
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    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
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  • 43
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    Weak interstellar lines in the visible spectrum of zeta Ophiuchi (1974)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; 193; Oct. 1
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  • 44
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    On the theory of thermal runaway in the hydrogen envelope of a white dwarf (1974)
    In:  Other Sources
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    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
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  • 45
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    Estimates of the Venus atmosphere optical characteristics with application to the problem of photographing its clouds and surface (1974)
    In:  Other Sources
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    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
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  • 46
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    Applicability of the diffusion approximation (1974)
    In:  Other Sources
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    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
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  • 47
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    Interactive design of large end rings on stiffened conical shells using composites (1974)
    In:  Other Sources
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    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.
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  • 48
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    Lyman-alpha imagery of Comet Kohoutek (1974)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Electrographic imagery of Comet Kohoutek in the 1100-1500 A wavelength range was obtained from a sounding rocket on Jan. 8, 1974, and from the Skylab space station on 13 occasions between Nov. 26, 1973 and Feb. 2, 1974. These images are predominantly due to Lyman-alpha (1216 A) emission from the hydrogen coma of the comet. The rocket pictures have been calibrated for absolute sensitivity and a hydrogen production rate has been determined. However, the Skylab camera suffered degradation of its sensitivity during the mission, and its absolute sensitivity for each observation can only be estimated by comparison of the comet images with those taken by the rocket camera, with imagery of the geocoronal Lyman-alpha glow, of the moon in reflected Lyman-alpha, and of ultraviolet-bright stars. The rocket and geocoronal comparisons are used to derive a preliminary, qualitative history of the development of the cometary hydrogen coma and the associated hydrogen production rate.
    Keywords: ASTROPHYSICS
    Type: Icarus; 23; Dec. 197
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  • 49
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    Interpretation of the anti-tail of Comet Kohoutek as a particle flow phenomenon (1974)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The appearance of a 'sunward' spike, opposite in apparent orientation to the normal Type-II tail in Comet Kohoutek is interpreted as evidence for large particles ejected near perihelion. It is shown that the shape and orientation can be satisfactorily explained in this manner, after consideration of the increased mass flow at decreasing heliocentric distance. The apparent length of the spike can be a measure of the particle size and density, and a value of about 0.004 g/sq cm for the product of particle size and density fits the Skylab observations.
    Keywords: ASTROPHYSICS
    Type: Icarus; 23; Dec. 197
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  • 50
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    A comment on gamma ray lines from He-4 (1974)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: It is pointed out that excited states of He-4 cannot produce gamma ray line emission of astrophysical significance, contrary to a recent suggestion of Reina et al. (1974). The only possible gamma-ray lines in He-4 are above 25 MeV, but their excitation cross sections appear to be so small that they are probably of little astrophysical significance.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics; 36; 2, No; Nov. 197
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  • 51
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    Violation of the Vogt-Russell theorem for homogeneous nondegenerate stars (1974)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: A systematic study is made of the number and types of solutions of the equilibrium equations of stellar structure, in the case of homogeneous stars of Population I over the mass range 2-1000 solar masses, with four different opacity representations. A variant of the usual fitting method permits the simultaneous investigation of convergence and tendency toward multiplicity of the solutions. Quadratic interpolation and extrapolation of Carson's new opacity tables produces a very large opacity at low temperatures that greatly affects the loose outer layers of massive stars, while leaving the cores practically unaffected. As a result, over a small mass range, well above 100 solar masses, triple solutions exist, always near an effective temperature of log Te = 4.73. A simple classification of the known exceptions to the Vogt-Russell theorem on the uniqueness of stellar structure is given.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; 194; Dec. 15
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  • 52
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    Neutrino emission from plasmons in strong magnetic fields (1974)
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    Publication Date: 2011-08-16
    Description: Neutrino pair emission from stellar interiors is investigated. The paper indicates that the proposed enhanced emission mode is a part of a transverse mode spectrum with a refraction index in the limit of infinity. It is concluded that in an astrophysical sense a very strong magnetic field does not have a significant effect on the emission rate of neutrinos from plasmons.
    Keywords: ASTROPHYSICS
    Type: Astrophysics and Space Science; 31; Nov. 197
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  • 53
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    X rays predicted from flares of UV Ceti stars (1974)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Keywords: ASTROPHYSICS
    Type: Nature; 252; Dec
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  • 54
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    Evidence for a corona of beta Geminorum (1974)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: A spectrometer was used on the satellite Copernicus to observe a chromospheric L alpha emission from the K0 giant beta Gem at 1218.4 A. This emission appears to be in the corona at temperatures near 260,000 deg K, since the ion it is identified with requires 77.4 eV to be produced.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; 193; Nov. 1
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  • 55
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    Boundary value problems with incremental plasticity in granular media (1974)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Discussion of the critical state concept in terms of an incremental theory of plasticity in granular (soil) media, and formulation of the governing equations which are convenient for a computational scheme using the finite element method. It is shown that the critical state concept with its representation by the classical incremental theory of plasticity can provide a powerful means for solving a wide variety of boundary value problems in soil media.
    Keywords: STRUCTURAL MECHANICS
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  • 56
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    Tentative identification of U93.174 as the molecular ion N2H/+/ (1974)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: On the basis of a consideration of the rotation constant and the hyperfine structure together with the results of an ab initio structural calculation it is suggested that the three closely space new interstellar lines near 93.174 GHz reported by Turner (1974) might have been produced by the molecular ion N2H(+). It is pointed out that the identification of N2H(+) is reasonable also in terms of current ideas of interstellar chemistry.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; 193; Oct. 15
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  • 57
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    A solution to the contact of two rough spherical surfaces (1974)
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    Publication Date: 2011-08-16
    Description: The influence of roughness on the interfacial pressure distribution in the contact of two spherical surfaces is considered. An approximate general solution is presented and it is shown that the pressure for all radii can be determined solely from a reference pressure which is, in turn, a function of two parameters - a dimensionless roughness and a dimensionless hardness. Values for the radius of contact are also presented.
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  • 58
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    Absolute radiometry and the solar constant (1974)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: A series of active cavity radiometers (ACRs) are described which have been developed as standard detectors for the accurate measurement of irradiance in absolute units. It is noted that the ACR is an electrical substitution calorimeter, is designed for automatic remote operation in any environment, and can make irradiance measurements in the range from low-level IR fluxes up to 30 solar constants with small absolute uncertainty. The instrument operates in a differential mode by chopping the radiant flux to be measured at a slow rate, and irradiance is determined from two electrical power measurements together with the instrumental constant. Results are reported for measurements of the solar constant with two types of ACRs. The more accurate measurement yielded a value of 136.6 plus or minus 0.7 mW/sq cm (1.958 plus or minus 0.010 cal/sq cm per min).
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  • 59
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    An experimental test of the homogeneity of the interstellar medium (1974)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Observations of nonthermal continuum radio emission at 750 MHz and hydrogen-line emission at 1420 MHz have been compared in order to test the extent to which cosmic-ray electrons, magnetic fields, and hydrogen gas coexist in the interstellar medium. If the interstellar medium is homogeneous in the sense that its constituents are mixed together and can interact, then regions of line and continuum emission should be spatially correlated. The measurements indicate that at most 28% of continuum emission in the Galaxy comes from such a homogeneous medium. The remaining nonthermal emission agrees in magnitude with the residual emission found by Berkhuijsen after subtraction of the polarized component of nonthermal emission. In addition, the data discussed here show that the major filamentary structures found in the two forms of emission rarely coincide spatially. Consequently, both the average and the exceptional structure in the medium indicate that the synchrotron-radiating magnetoplasma and the neutral hydrogen gas are not closely interacting in the present state of the medium.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; 194; Dec. 1
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  • 60
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    Origin of fifteen cosmic dust particles intercepted by Pioneer 8 and 9 (1974)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Consistent data for more than 8 years have been obtained from two identical cosmic dust particle experiments on board the space probes Pioneer 8 and 9. The two spacecraft are in direct heliocentric orbits with perihelia between 0.75 AU and 1.00 AU. On the basis of the data it is concluded that the majority of dust particles having elliptical orbits detected by the two space probes show orbital characteristics of Apollo group asteroids which originated from residual nuclei of short-period comets.
    Keywords: ASTROPHYSICS
    Type: Nature; 252; Dec. 13
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  • 61
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    Mixed mode stress field effect in adhesive fracture (1974)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Numerical or analytical analyses were performed on seven different test specimens including blister test, 90-degree peel test, torsion test, and various cone tests. These specimens are in general subjected to complex stress fields having various amounts of Mode I, Mode II, and Mode III loads. The specimens were then constructed using polymethyl methacrylate for the adherends and a transparent polyurethane elastomer (Solithane 113) for the adhesive. This combination permitted direct observation of the bondline as load was applied. Although initial debonds as well as bond end termination singularities were present in all specimens, in some cases the debond did not initiate at the singularity points as would normally have been expected. An explanation for this behavior is presented, as well as a comparison of loading mode effect on those specimens for which the debond did propagate from a bond terminus singular point.
    Keywords: STRUCTURAL MECHANICS
    Type: International Journal of Fracture; 10; Dec. 197
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  • 62
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    Dependence of plate-bending finite element deflections and eigenvalues on Poisson's ratio (1974)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Keywords: STRUCTURAL MECHANICS
    Type: AIAA Journal; 12; Oct. 197
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  • 63
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    Fracture initiation and propagation in a cylindrical shell containing an initial surface flaw (1974)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: An attempt is made to provide the necessary analytical tools for the application of two different types of fracture criteria to shell structures. Of particular interest is the problem of fracture propagation and arrest in a cylindrical pressure vessel containing an initial surface flaw. It is assumed that the flaw has the most unfavorable geometry and orientation, namely, it is a crack lying on a meridional plane. Stress intensity factor for a part-through crack, and a surface or internal crack with a fully yielded net ligament are considered. Attention is given to constant delta curves for depressurization studies and to depressurization and crack arrest in pressure vessels.
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  • 64
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    An overview of high temperature metal fatigue: Aspects covered by the 1973 International Conference on Creep and Fatigue (1974)
    In:  CASI
    Details
    Publication Date: 2012-05-22
    Description: A summary of papers is presented which covers the following broad aspects of high temperature metal fatigue: (1) materials development and characterization; (2) environmental factors, including air, vacuum, helium, iodine, sodium, and radiation environments; (3) general fatigue life relationships; (4) crack growth laws; (5) design code activities; and (6) design and service experience. Illustrative tables accompany the summary.
    Keywords: STRUCTURAL MECHANICS
    Type: AGARD Low Cycle High Temp. Fatigue; 47 p
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  • 65
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    Upper atmospheres and diagnostic measurements (1974)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: Candidate space missions to study the temperature profiles, and ratios of hydrogen to helium in outer planet atmospheres are discussed in terms of scientific payloads for optical occultation, radio occultation, and thermometer measurements.
    Keywords: ASTROPHYSICS
    Type: Dynatrend, Inc. Proc. of Outer Planet Probe Technol. Workshop, Sect. 1 through 11; 8 p
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  • 66
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    Estimates of the size of particles in Saturn's rings and their cosmogonic implications (1974)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Near infrared ice band measurements, radar and radio observations, and implications of the size estimates of particles in Saturn's rings are discussed. The measurements are compared to the Poynting-Robetson effect and a possible mechanism by which the size of the particles may significantly change after the initial formulation of the material in the rings is proposed.
    Keywords: ASTROPHYSICS
    Type: The Rings of Saturn; p 107-123
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  • 67
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    The atmosphere of the rings of Saturn (1974)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: Outgassing of H and OH from Saturn's rings and the possibility of detecting it are examined. The source gas around the rings is computed after which the products of ice, H2O, H, and OH and the physical mechanisms that produce these species are given. Production rates for the ice products are discussed.
    Keywords: ASTROPHYSICS
    Type: NASA, Washington The Rings of Saturn; p 125-129
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  • 68
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    Distribution and size of elements of Saturn's rings as inferred from 12-cm radar observations (1974)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A 64m radar antenna was used to observe Saturn's rings at 12.6 cm wavelength, with reduced Doppler spread. The results show a positive radar return corresponding to about a 60 percent return from an isotropic scatterer with the projected area of the rings, allowing for the Cassini division. A radar spectrogram of the rings is shown with power density plotted against Doppler frequency shift.
    Keywords: ASTROPHYSICS
    Type: NASA, Washington The Rings of Saturn; p 73-82
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  • 69
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    Variations in the infrared brightness temperature of Saturn's rings (1974)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: After adjusting for the decreased Sun-Saturn distance and adjusting all measurements to B ring values only, it is shown that the temperature variations are not as large as was thought. Various models of the multilayer agglomerate of particles of Saturn's rings are evaluated. It is recommended that the difference between the 11 and 20 micron brightness temperatures should be explained by a satisfactory model.
    Keywords: ASTROPHYSICS
    Type: NASA, Washington The Rings of Saturn; p 65-72
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  • 70
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    Saturn's ring particles and space vehicle design (1974)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Spacecraft design is discussed for probing Saturn's rings. Ring particles are also considered, emphasizing material outside of ring A and the hazard this might imply to a spacecraft crossing the ring plane beyond ring A.
    Keywords: ASTROPHYSICS
    Type: NASA, Washington The Rings of Saturn; p 29-38
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    Ring particle sizes and composition derived from eclipse cooling curves and reflection spectra (1974)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The probable chemistry of the Saturn rings is reviewed. Reflectance spectra for H20 and NH3 frosts and Saturn's rings are compared, along with temperature dependence of 1.6 microns water frost feature. The reflection spectra of Galilean satellite J2 and water frost are also reviewed.
    Keywords: ASTROPHYSICS
    Type: NASA, Washington The Rings of Saturn; p 51-63
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  • 72
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    Model of Saturn's rings that satisfies the observed phase curve for optical scattering (1974)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The effects of multiple anisotropic scattering were calculated, including the solar penumbra effect for shadowing computations. The classical model was matched to observations, including the wavelength dependence, by varying the particle albedo as a function of wavelength. A scattering diagram is also presented showing the relative amount of primary and higher-order scattering necessary to match the B ring brightness and the shape of the phase curve.
    Keywords: ASTROPHYSICS
    Type: NASA, Washington The Rings of Saturn; p 17-28
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  • 73
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    Structure of Saturn's rings: Optical and dynamical considerations (1974)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The photometric phase curves of Saturn's rings are considered, as well as a conflict between dynamical and photometric models of the rings. The dependence of ring brightness on angular separation of the earth and sun as viewed from Saturn is discussed. The nonlinear brightness surge is interpreted. Some quantitative calculations were carried out for bodies in and near the asteroidal belt. Predicted density profiles of the ring obtained with Mimas in an eccentric orbit and in a circular orbit are also included.
    Keywords: ASTROPHYSICS
    Type: NASA, Washington The Rings of Saturn; p 3-15
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  • 74
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    Identification of structural parameters from helicopter dynamic test data (1974)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A method is presented for obtaining the mass, stiffness, and damping parameters of a linear mathematical model, having fewer degrees of freedom than the structure it represents, directly from dynamic response measurements on the actual helicopter without a priori knowledge of the physical characteristics of the fuselage. The only input information required in the formulation is the approximate natural frequency of each mode and mobility data measured proximate to these frequencies with sinusoidal force excitation applied at only one point on the vehicle. The practicality and numerical soundness of the theoretical development was demonstrated through a computer simulation of an experimental program.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Ames Res. Center Rotorcraft Dyn.; p 239-248
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  • 75
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    Application of antiresonance theory to helicopters (1974)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Antiresonance theory is the principle underlying nonresonant nodes in a structure, and covers both nonresonant nodes occurring naturally and those introduced by devices such as dynamic absorbers and antiresonant isolators. The dynamic antiresonant vibration isolator (DAVI) and the nodale module are examples of the applications of transfer antiresonances. It is shown that antiresonances are eigenvalues, and that they can be determined by matrix iteration. Applications of antiresonance theory to helicopter engineering problems, using the antiresonant eigenvalue equation are suggested.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Ames Res. Center Rotorcraft Dyn.; p 101-106
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  • 76
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    Correlation of finite-element structural dynamic analysis with measured free vibration characteristics for a full-scale helicopter fuselage (1974)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The correlation achieved with each program provides the material for a discussion of modeling techniques developed for general application to finite-element dynamic analyses of helicopter airframes. Included are the selection of static and dynamic degrees of freedom, cockpit structural modeling, and the extent of flexible-frame modeling in the transmission support region and in the vicinity of large cut-outs. The sensitivity of predicted results to these modeling assumptions are discussed. Both the Sikorsky Finite-Element Airframe Vibration analysis Program (FRAN/Vibration Analysis) and the NASA Structural Analysis Program (NASTRAN) have been correlated with data taken in full-scale vibration tests of a modified CH-53A helicopter.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Ames Res. Center Rotorcraft Dyn.; p 67-80
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  • 77
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    Rotating stars (1974)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Keywords: ASTROPHYSICS
    Type: JPL Proc. of the Intern. Colloq. on Drops and Bubbles, Vol. 1; p 11-34
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  • 78
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    The fission theory of binary stars (1974)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Keywords: ASTROPHYSICS
    Type: JPL Proc. of the Intern. Colloq. on Drops and Bubbles, Vol. 1; p 1-10
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  • 79
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    Transonic single-mode flutter and buffet of a low aspect ratio wing having a subsonic airfoil shape (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Transonic flutter and buffet results obtained from wind-tunnel tests of a low aspect ratio semispan wing model are presented. The tests were conducted to investigate potential transonic aeroelastic problems of vehicles having subsonic airfoil sections. The model employed NACA 00XX-64 airfoil sections in the streamwise direction and had a 14 deg leading edge sweep angle. Aspect ratio, and average thickness were 4.0, 0.35, and 8 percent, respectively. The model was tested at Mach numbers from 0.6 to 0.95 at angles of attack from 0 deg to 15 deg. Two zero lift flutter conditions were found that involved essentially single normal mode vibrations. With boundary layer trips on the model, flutter occurred in a narrow Mach number range centered at about Mach 0.90. The frequency and motion of this flutter were like that of the first normal mode vibration. With the trips removed flutter occurred at a slightly high Mach number but in a mode strongly resembling that of the second normal mode.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-TN-D-7346 , A-4966
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  • 80
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    Limits on the neutral hydrogen content of Coma and other clusters of galaxies (1974)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics; 36; 3, De; Dec. 197
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  • 81
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    Binary stellar winds (1974)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: Stellar winds from a binary star will interact with each other along a contact discontinuity. We discuss qualitatively the geometry of the flow and field resulting from this interaction in the simplest case where the stars and winds are identical. We consider the shape of the critical surface (defined as the surface where the flow speed is equal to the sound speed) as a function of stellar separation and the role of shock waves in the flow field. The effect of stellar spin and magnetic sectors on the field configuration is given. The relative roles of mass loss and magnetic torque in the evolution of orbital parameters are discussed.
    Keywords: ASTROPHYSICS
    Type: Astrophysics and Space Science; 31; Dec. 197
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  • 82
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    A search for microwave emission from CH in Comet Kohoutek /1973f/ (1974)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: A search was conducted for the three 9-cm transitions of the ground state Lambda-doublet of CH in comet Kohoutek, using the CSIRO 64-m radio telescope and the Onsala Space Observatory's 25.6-m telescope. No lines were detected during the observing periods, and upper limits are given for the corresponding antenna temperatures.
    Keywords: ASTROPHYSICS
    Type: Icarus; 23; Dec. 197
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  • 83
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    Molecule searches in Comet Kohoutek /1973f/ at microwave frequencies (1974)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: Nine transitions of the possible parent molecules H2O, NH3, CH3OH and N2O as well as the OH radical were searched for in Comet Kohoutek (1973f) in the frequency range 22.2-25.2 GHz. These molecules were not detected, but the upper limits for the optical depth, mean column density and the production rate are derived for each of the molecules. These results are discussed and compared with the reported detections of HCN and CH3CN emission and OH absorption.
    Keywords: ASTROPHYSICS
    Type: Icarus; 23; Dec. 197
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    On the nature of the anti-tail of Comet Kohoutek /1973f/. I - A working model (1974)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: The model derived for the anti-tail of Comet Kohoutek describes it as a flat formation, confined essentially to the comet's orbit plane and composed of relatively heavy particles (mostly in the size range 0.1-1 mm) whose motions are controlled by solar gravity and solar radiation pressure. Almost all the material was produced by the comet before perihelion at a rate about an order of magnitude higher than for Comets Arend-Roland and Bennett. The latent heat of vaporization of the particle material is estimated at 40-45 kcal/mole or higher.
    Keywords: ASTROPHYSICS
    Type: Icarus; 23; Dec. 197
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  • 85
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    An upper limit on the evolution of carbon monoxide from Comet Kohoutek (1974)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: An upper limit on the rate of evolution of CO from Comet Kohoutek has been obtained from a search for resonant scattering of sunlight near 4.7 microns. The observations were made approximately two months after perihelion. The rate of evolution of CO at that time was apparently less than that of CH3CN observed before perihelion.
    Keywords: ASTROPHYSICS
    Type: Icarus; 23; Dec. 197
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  • 86
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    Interstellar carbon I lines in zeta Ophiuchi (1974)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: With two f-values of C I lines obtained from the spectra of zeta Pup and gamma(2) Vel, it is shown that the interstellar C I spectrum in zeta Oph obeys an optical-depth relation similar to that for Na I, and the relative strengths of 19 multiplets are determined from this relation. The dominant processes which excite neutral carbon are used to calculate populations of the fine-structure levels as functions of the density of H nuclei and the temperature, and evidence is found that the C I lines are formed in the dense cloud in front of zeta Oph at a heliocentric velocity of -14.4 km/s. It is noted that the observed column-density ratios of the neutral carbon fine-structure levels lead to a total H nuclei density of about 220 to 660 per cu cm, while the electron density and observed C(+) abundance indicate a value of 10,000 per cu cm, with a 0.05 pc thick gas layer.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics; 37; 2, De; Dec. 197
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    Transverse vibrations of non-uniform beams (1974)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: The free vibrations of elastic beams with nonuniform characteristics are investigated theoretically by a new method. The new method is seen to combine the advantages of a finite element approach and of a Rayleigh-Ritz analysis. Comparison with the known analytical results for uniform beams shows good convergence of the method for natural frequencies and modes. For internal shear forces and bending moments, the rate of convergence is less rapid. Results from experiments conducted with a cantilevered helicopter blade with strong nonuniformities and also from alternative theoretical methods, indicate that the theory adequately predicts natural frequencies and mode shapes. General guidelines for efficient use of the method are presented.
    Keywords: STRUCTURAL MECHANICS
    Type: Journal of Sound and Vibration; 37; Dec. 22
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  • 88
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    CNO abundances and hydrodynamic models of the nova outburst. III - 0.5 solar mass models with enhanced carbon, oxygen, and nitrogen (1974)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: Consideration of the evolution of thermonuclear runaways in the hydrogen-rich envelopes of 0.5 solar mass carbon-oxygen white dwarfs. The larger radii of these stars, compared with the 1.00 solar mass white dwarfs, results in a lesser degree of degeneracy at the same depth in the star. Four models of luminosity with .00355 solar luminosity, differing only in the initial abundances of C-12, N-14, and O-16, are presented. The degree of enhancement required to produce mass ejection, and thereby a nova-type outburst, is greater than for the 1.00 solar mass model. Nevertheless, the evolution of the 0.5 solar mass model that ejected material is very similar to that of the 1.00 solar mass models, and it also ejects significant amounts of C-13, N-15, and O-17 into the interstellar medium. The 0.5 solar mass outburst is considerably less intense than the 1.00 solar mass outburst (even under optimum conditions), and this lower mass behavior is interpreted as associated with the observed outburst of the slowest novae.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; 192; Sept. 15
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    Ultraviolet spectrophotometry of Sirius from Gemini 12 (1974)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: The spectral energy distribution of Sirius between 2500 and 3700 A at a resolution of 7 A is obtained from plates taken on Gemini 12. The agreement with other observations and the most recent line-blanketed model atmospheres is good. The equivalent width of the Mg II doublet near 2800 A is 6.0 A, if the continuum level is represented by regions near 2650 and 2910 A. This is consistent with expectations for a hot Am star and implies line blocking of up to 15% in this wavelength region.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; 192; Sept. 15
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  • 90
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    Non-linear behavior of fiber composite laminates (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The non-linear behavior of fiber composite laminates which results from lamina non-linear characteristics was examined. The analysis uses a Ramberg-Osgood representation of the lamina transverse and shear stress strain curves in conjunction with deformation theory to describe the resultant laminate non-linear behavior. A laminate having an arbitrary number of oriented layers and subjected to a general state of membrane stress was treated. Parametric results and comparison with experimental data and prior theoretical results are presented.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-CR-2313 , TFR/7309
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  • 91
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    Failure criteria for viscoelastic materials (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Research projects concerned with developing a theory of fracture of materials are discussed. The effects of the geometry of the structure and the loads acting on the structure as they influence the failure process are analyzed. The effects of the viscoelastic deformation characteristics of the bulk elastomer on failure behavior are examined. Additional material parameters which control the fracture process are identified.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-CR-138125 , GALCIT-120
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  • 92
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    Advance development of a technique for characterizing the thermomechanical properties of thermally stable polymers (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The torsional braid experiment has been interfaced with a centralized hierarchical computing system for data acquisition and data processing. Such a system, when matched by the appropriate upgrading of the monitoring techniques, provides high resolution thermomechanical spectra of rigidity and damping, and their derivatives with respect to temperature.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-CR-138123
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    Analysis of laminated, composite, circular cylindrical shells with general boundary conditions (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: This report develops: (1) a refined approximate theory for the static and dynamic analyses of finite, laminated, composite, circular cylindrical shells with general boundary conditions; (2) an exact three-dimensional analysis of simply supported, laminated, composite, circular cylindrical shells, and (3) a thin-shell theory for laminated, composite, circular cylindrical shells. In the refined approximate theory the displacements are assumed piecewise linear across the thickness and the effects of transverse shear deformations and transverse normal stress are included. A variational approach is followed to obtain the governing differential equations and boundary conditions. A general solution of the governing differential equations is also presented. The results obtained by using the refined approximate theory and the thin-shell theory are compared with the exact results for the case of free vibrations of simply supported, laminated, composite, circular cylindrical shells. The refined approximate theory is very accurate, even for thick shells with short nodal distances, whereas thin-shell theory is reasonably accurate only for thin shells at moderate nodal distances and wave number less than 2.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-TR-R-412 , L-8828
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    Holographic nondestructive tests performed on composite samples of ceramic-epoxy-fiberglass sandwich structure (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: When a hologram storing more than one wave is illuminated with coherent light, the reconstructed wave fronts interfere with each other or with any other phase-related wave front derived from the illuminating source. This multiple wave front comparison is called holographic interferometry, and its application is called holographic nondestructive testing (HNDT). The theoretical aspects of HNDT techniques and the sensitivity of the holographic system to the geometrical placement of the optical components are briefly discussed. A unique HNDT system which is mobile and possesses variable sensitivity to stress amplitude is discribed, the experimental evidence of the application of this system to the testing of the hidden debonds in a ceramic-epoxy-fiberglass structure used for sample testing of the radome of the Pershing missile system is presented.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-TR-R-430 , M-461
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    Procedures for experimental measurement and theoretical analysis of large plastic deformations (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Theoretical equations are derived and analytical procedures are presented for the interpretation of experimental measurements of large plastic strains in the surface of a plate. Orthogonal gage lengths established on the metal surface are measured before and after deformation. The change in orthogonality after deformation is also measured. Equations yield the principal strains, deviatoric stresses in the absence of surface friction forces, true stresses if the stress normal to the surface is known, and the orientation angle between the deformed gage line and the principal stress-strain axes. Errors in the measurement of nominal strains greater than 3 percent are within engineering accuracy. Applications suggested for this strain measurement system include the large-strain-stress analysis of impact test models, burst tests of spherical or cylindrical pressure vessels, and to augment small-strain instrumentation tests where large strains are anticipated.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-TM-X-3027 , E-7661
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  • 96
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    Analysis of three-point-bend test for materials with unequal tension and compression properties (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An analysis capability is described for the three-point-bend test applicable to materials of linear but unequal tensile and compressive stress-strain relations. The capability consists of numerous equations of simple form and their graphical representation. Procedures are described to examine the local stress concentrations and failure modes initiation. Examples are given to illustrate the usefulness and ease of application of the capability. Comparisons are made with materials which have equal tensile and compressive properties. The results indicate possible underestimates for flexural modulus or strength ranging from 25 to 50 percent greater than values predicted when accounting for unequal properties. The capability can also be used to reduce test data from three-point-bending tests, extract material properties useful in design from these test data, select test specimen dimensions, and size structural members.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-TN-D-7572 , E-7544
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  • 97
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    FORTRAN 4 programs for summarization and analysis of fracture trace and lineament patterns (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Systematic and detailed analysis of lineament and fracture trace patterns has long been neglected because of the large number of observations involved in such an analysis. Three FORTRAN 4 programs were written to facilitate this manipulation. TRANSFORM converts the initial fracture map data into a format compatible with AZMAP, whose options allow repetitive manipulation of the data for optimization of the analysis. ROSE creates rose diagrams of the fracture patterns suitable for map overlays and tectonic interpretation. Examples are given and further analysis techniques using output from these programs are discussed.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-TM-X-70596 , X-644-74-3
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  • 98
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    Sensitivity analysis of torsional vibration characteristics of helicopter rotor blades. Part 2: Aerodynamics and sensitivity analysis (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A theoretical investigation of dynamic response characteristics of rotor blades was carried out with special emphasis on torsional degrees-of-freedom. Coupled equations of motion for flapwise bending and torsion were formulated at varying azimuth positions for rotor blades with noncollinear aerodynamic, elastic and mass axes. Both structural and aerodynamic mass, damping and stiffness coefficients were included. The variations of a sample blade at different flight conditions were investigated from these equations. The obtained numerical results were illustrated. The sensitivity of overall blade vibration characteristics to torsional oscillations was also investigated from the equations of motion for the sample blade. The illustrated results show the importance of torsional degrees-of-freedom in rotor blade analysis. Various possibilities of improving the overall response by tuning blade geometric, structural and aerodynamic characteristics are discussed.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-CR-2380
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  • 99
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    Assembly and analysis of fragmentation data for liquid propellant vessels (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Fragmentation data was assembled and analyzed for exploding liquid propellant vessels. These data were to be retrieved from reports of tests and accidents, including measurements or estimates of blast yield, etc. A significant amount of data was retrieved from a series of tests conducted for measurement of blast and fireball effects of liquid propellant explosions (Project PYRO), a few well-documented accident reports, and a series of tests to determine auto-ignition properties of mixing liquid propellants. The data were reduced and fitted to various statistical functions. Comparisons were made with methods of prediction for blast yield, initial fragment velocities, and fragment range. Reasonably good correlation was achieved. Methods presented in the report allow prediction of fragment patterns, given type and quantity of propellant, type of accident, and time of propellant mixing.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-CR-134538
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    Stress anisotropy and concentration effects in high pressure measurements (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Sodium chloride is used as an internal pressure standard in high pressure research. Possible corrections are discussed which are needed in the calibration of this standard due to the independent effects of stress anisotropy and stress concentration in pressure vessels. The first is due to the lack of a truly hydrostatic state of stress in solid state pressure vessels. The second is due to the difference in the compressibilities between the pressure transmitting substances (sodium chloride) and a stiffer test specimen. These two corrections are then combined and a total correction, as a function of measured pressure, is discussed for two systems presently in use. The predicted value of the combined effect is about 5-10% of the pressure at 30 GPa.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-CR-142600 , REPT-2345
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