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  • STRUCTURAL MECHANICS  (795)
  • ASTROPHYSICS
  • 1980-1984  (780)
  • 1970-1974  (746)
  • 1935-1939
  • 1980  (780)
  • 1974  (417)
  • 1970  (329)
Collection
Years
  • 1980-1984  (780)
  • 1970-1974  (746)
  • 1935-1939
Year
  • 1
    Publication Date: 2005-11-27
    Description: Theoretical calculations and holographic measurements on transverse deflections of astronomical mirror blank
    Keywords: STRUCTURAL MECHANICS
    Type: NASA, WASHINGTON OPT. TELESCOPE TECHNOL. 1970; P 287-270
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  • 2
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    In:  CASI
    Publication Date: 2005-11-27
    Description: Dynamic analysis to predict space vehicle response to atmospheric disturbances with reference to space shuttle
    Keywords: STRUCTURAL MECHANICS
    Type: SPACE TRANSPORTATION SYSTEM TECHNOL. SYMP., VOL. 2 JUL. 1970; P 331-348
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  • 3
    Publication Date: 2005-11-27
    Description: Load alleviation and structural mode control potential for space shuttle vehicle
    Keywords: STRUCTURAL MECHANICS
    Type: SPACE TRANSPORTATION SYSTEM TECHNOL. SYMP., VOL. 2 JUL. 1970; P 349-363
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  • 4
    Publication Date: 2005-11-27
    Description: Basic vibration characteristics and random response in thin panels
    Keywords: STRUCTURAL MECHANICS
    Type: SPACE TRANSPORTATION SYSTEM TECHNOL. SYMP., VOL. 2 JUL. 1970; P 43-57
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  • 5
    Publication Date: 2005-11-27
    Description: Communications satellite antenna structure dynamic response to random loads in launch environment
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. LEWIS RES. CENTER SPACE TRANSPORTATION SYSTEM TECHNOL. SYMP., VOL. 2 JUL. 1970; P 301-329
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  • 6
    Publication Date: 2005-11-27
    Description: Staging dynamics for piggyback space shuttles
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. LEWIS RES. CENTER SPACE TRANSPORTATION SYSTEM TECHNOL. SYMP., VOL. 2 JUL. 1970; P 123-142
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  • 7
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    Publication Date: 2005-11-27
    Description: Lifting and control surface flutter on space shuttles
    Keywords: STRUCTURAL MECHANICS
    Type: SPACE TRANSPORTATION SYSTEM TECHNOL. SYMP., VOL. 2 JUL. 1970; P 177-198
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  • 8
    Publication Date: 2005-11-27
    Description: Control systems for vibration isolation of large structures and vacuum chambers
    Keywords: STRUCTURAL MECHANICS
    Type: NASA, WASHINGTON OPT. TELESCOPES TECHNOL. 1970; P 733-749
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  • 9
    Publication Date: 2005-11-27
    Description: Thermal environment effects on alignment behavior of structural joints and assemblies of reentry vehicle and Mars landing module
    Keywords: STRUCTURAL MECHANICS
    Type: OPT. TELESCOPE TECHNOL. 1970; P 335-349
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  • 10
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    In:  CASI
    Publication Date: 2005-11-27
    Description: Vibration response and acoustic fatigue characteristics of space shuttle thermal protection system design concepts
    Keywords: STRUCTURAL MECHANICS
    Type: SPACE TRANSPORTATION SYSTEM TECHNOL. SYMP., VOL. 2 JUL. 1970; P 273-284
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  • 11
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    In:  CASI
    Publication Date: 2005-11-27
    Description: Dynamic model for obtaining response data for space shuttle
    Keywords: STRUCTURAL MECHANICS
    Type: SPACE TRANSPORTATION SYSTEM TECHNOL. SYMP., VOL. 2 JUL. 1970; P 29-42
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  • 12
    Publication Date: 2005-11-27
    Description: Pogo effect influence on aerodynamic phenomena in rocket afterbody
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. LEWIS RES. CENTER SPACE TRANSPORTATION SYSTEM TECHNOL. SYMP., VOL. 2 JUL. 1970; P 263-265
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  • 13
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    In:  CASI
    Publication Date: 2005-11-27
    Description: Ring reinforcements for damping structural deformation in orthotropic mirror design
    Keywords: STRUCTURAL MECHANICS
    Type: NASA, WASHINGTON OPT. TELESCOPE TECHNOL. 1970; P 283-286
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  • 14
    Publication Date: 2005-11-27
    Description: Finite element method for structural design of astronomical mirrors
    Keywords: STRUCTURAL MECHANICS
    Type: NASA, WASHINGTON OPT. TELESCOPE TECHNOL. 1970; P 249-255
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  • 15
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    In:  CASI
    Publication Date: 2005-11-27
    Description: Transient loading considerations for shuttle design
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. LEWIS RES. CENTER SPACE TRANSPORTATION SYSTEM TECHNOL. SYMP., VOL. 2 JUL. 1970; P 79-100
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  • 16
    Publication Date: 2005-11-27
    Description: Assessment of techniques for determining eigenvalues of large systems
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. LEWIS RES. CENTER SPACE TRANSPORTATION SYSTEM TECHNOL. SYMP., VOL. 2 JUL. 1970; P 4-27
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  • 17
    Publication Date: 2005-11-27
    Description: Using finite element method in analysis and design of optical space telescopes
    Keywords: STRUCTURAL MECHANICS
    Type: OPT. TELESCOPE TECHNOL. 1970; P 401-415
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  • 18
    Publication Date: 2005-11-27
    Description: Structural analysis for optimal load carrying substrate members of lightweight astronomical mirror
    Keywords: STRUCTURAL MECHANICS
    Type: NASA, WASHINGTON OPT. TELESCOPE TECHNOL. 1970; P 257-280
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  • 19
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    In:  CASI
    Publication Date: 2005-11-27
    Description: User checklist for spacecraft boom selection with review of structural, electrical and mechanical properties
    Keywords: STRUCTURAL MECHANICS
    Type: JPL PROC. OF THE 4TH AEROSPACE MECH. SYMP. 15 JAN. 1970; P 51-54
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  • 20
    Publication Date: 2005-11-27
    Description: Acoustic, vibration, and shock environments in designing orbital telescopes
    Keywords: STRUCTURAL MECHANICS
    Type: OPT. TELESCOPE TECHNOL. 1970; P 389-400
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  • 21
    Publication Date: 2005-11-27
    Description: Coupled structure-propulsion system instability /POGO/ prevention on space shuttle
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. LEWIS RES. CENTER SPACE TRANSPORTATION SYSTEM TECHNOL. SYMP., VOL. 2 JUL. 1970; P 249-262
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  • 22
    Publication Date: 2005-11-27
    Description: Supersonic panel flutter of space shuttle heat shields with flexible supports
    Keywords: STRUCTURAL MECHANICS
    Type: SPACE TRANSPORTATION SYSTEM TECHNOL. SYMP., VOL. 2 JUL. 1970; P 199-221
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  • 23
    Publication Date: 2005-11-27
    Description: Design and development of deployment fixture for simulated zero gravity testing of large area solar array
    Keywords: STRUCTURAL MECHANICS
    Type: JPL PROC. OF THE 4TH AEROSPACE MECH. SYMP. 15 JAN. 1970; P 83-89
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  • 24
    Publication Date: 2005-11-27
    Description: Mechanical and thermal properties of materials for five spacecraft boom designs
    Keywords: STRUCTURAL MECHANICS
    Type: JPL PROC. OF THE 4TH AEROSPACE MECH. SYMP. 15 JAN. 1970; P 43-45
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  • 25
    Publication Date: 2005-11-27
    Description: Customer opinion of design of aerospace mechanisms
    Keywords: STRUCTURAL MECHANICS
    Type: JPL PROC. OF THE 4TH AEROSPACE MECH. SYMP. 15 JAN. 1970; P 91-94
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  • 26
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    Publication Date: 2005-11-27
    Description: Performance summary and spacecraft applications of booms with future trends
    Keywords: STRUCTURAL MECHANICS
    Type: JPL PROC. OF THE 4TH AEROSPACE MECH. SYMP. 15 JAN. 1970; P 55-72
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  • 27
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    In:  CASI
    Publication Date: 2004-10-30
    Description: Space shuttle liftoff dynamics
    Keywords: STRUCTURAL MECHANICS
    Type: SPACE TRANSPORTATION SYSTEM TECNOL. SYMP., VOL. 2 JUL. 1970; P 101-122
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  • 28
    Publication Date: 2006-04-25
    Description: NASA computer program for dynamic structural analysis in stress and thermal deformation problems
    Keywords: STRUCTURAL MECHANICS
    Type: NIFICANT ACCOMPLISHMENTS IN SCI. AND TECHNOL. AT GODDARD SPACE FLIGHT CENTER 1970; P 221-224
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  • 29
    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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  • 30
    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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  • 31
    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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  • 32
    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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  • 33
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    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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  • 34
    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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  • 35
    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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  • 36
    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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  • 37
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    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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  • 38
    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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  • 39
    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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  • 40
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    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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  • 41
    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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  • 42
    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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  • 43
    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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  • 44
    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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  • 45
    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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  • 46
    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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  • 47
    Publication Date: 2011-08-16
    Description: Bond rupture and fracture in semicrystalline polymers, noting agreement with random length molecular tie chain scission model
    Keywords: STRUCTURAL MECHANICS
    Type: ; TROPHYSICAL JOURNAL
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  • 48
    Publication Date: 2011-08-16
    Description: Optimum design for buckling prevention in cylindrical shells under lateral pressure
    Keywords: STRUCTURAL MECHANICS
    Type: BL. IN STRESS ANALYSIS AND OPTIMUM DESIGN FEB. 1970 (SEE N71-24642 13-32) 13-32/
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  • 49
    Publication Date: 2011-08-16
    Description: Stress analysis of unidirectionally reinforced, composite plates with holes
    Keywords: STRUCTURAL MECHANICS
    Type: BL. IN STRESS ANALYSIS AND OPTIMUM DESIGN FEB. 1970 (SEE N71-24642 13-32) 13-32/
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  • 50
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    Publication Date: 2011-08-16
    Description: Stress analysis of thin shells with large deflections loaded into strain hardening range
    Keywords: STRUCTURAL MECHANICS
    Type: BL. IN STRESS ANALYSIS AND OPTIMUM DESIGN FEB. 1970 (SEE N71-24642 13-32) 13-32/
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  • 51
    Publication Date: 2011-08-16
    Description: Stress concentration on five ply, fiber reinforced plates with circular holes
    Keywords: STRUCTURAL MECHANICS
    Type: BL. IN STRESS ANALYSIS AND OPTIMUM DESIGN FEB. 1970 (SEE N71-24642 13-32) 13-32/
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  • 52
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    Publication Date: 2011-08-16
    Description: Behavior of various alloys, polymers and composites
    Keywords: STRUCTURAL MECHANICS
    Type: MATER. RES. SEP. 1970; P 37-55
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  • 53
    Publication Date: 2011-08-16
    Description: Structural configurations effect on momentum imparted to spacecraft by hypervelocity meteoroid impact
    Keywords: STRUCTURAL MECHANICS
    Type: ; ADEMIE DES SCIENCES
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  • 54
    Publication Date: 2011-08-16
    Description: Stress-strain diagram for nonhomogeneous composite with circular inclusion using Hookes law
    Keywords: STRUCTURAL MECHANICS
    Type: BL. IN STRESS ANALYSIS AND OPTIMUM DESIGN FEB. 1970 (SEE N71-24642 13-32) 13-32/
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  • 55
    Publication Date: 2011-08-16
    Description: FORTRAN program for stresses in nonhomogeneous elastic plate with circular hole
    Keywords: STRUCTURAL MECHANICS
    Type: BL. IN STRESS ANALYSIS AND OPTIMUM DESIGN FEB. 1970 (SEE N71-24642 13-32) 13-32/
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  • 56
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    Publication Date: 2011-08-16
    Description: Aeroelastic and aerothermoelastic development of winged interorbital space shuttle concerning panel flutter, stability and nonstationary lifting surface theory
    Keywords: STRUCTURAL MECHANICS
    Type: ; ADEMIE DES SCIENCES
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  • 57
    Publication Date: 2011-08-16
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics; 37; 1, De; Dec. 197
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  • 58
    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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  • 59
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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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  • 60
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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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  • 61
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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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  • 62
    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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  • 63
    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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  • 64
    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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  • 65
    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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  • 66
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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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  • 67
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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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  • 68
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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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  • 69
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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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  • 70
    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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  • 71
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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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  • 72
    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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  • 73
    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
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  • 74
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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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  • 75
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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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  • 76
    Publication Date: 2011-08-16
    Description: Fracture mechanics applications in stress analysis and structural design, considering rocket motor case failure
    Keywords: STRUCTURAL MECHANICS
    Type: ; DIOTEKHNIKA (
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  • 77
    Publication Date: 2011-08-16
    Description: Filamentary crystal growth associated with hypervelocity microparticles impact upon Cu foil
    Keywords: STRUCTURAL MECHANICS
    Type: ; ADEMIE DES SCIENCES
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  • 78
    Publication Date: 2011-08-16
    Description: Nonconservative problems motion stability analysis based on restricted admissible displacements, establishing two variational principles
    Keywords: STRUCTURAL MECHANICS
    Type: ; ADEMIE DES SCIENCES
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  • 79
    Publication Date: 2011-08-16
    Description: Longitudinal wave propagation in variable section bars, solving hyperbolic equation of motion by perturbation method
    Keywords: STRUCTURAL MECHANICS
    Type: ; YAL SOCIETY (
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  • 80
    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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  • 81
    Publication Date: 2011-08-16
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; 194; Dec. 15
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  • 82
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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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  • 83
    Publication Date: 2011-08-16
    Keywords: STRUCTURAL MECHANICS
    Type: AIAA Journal; 12; Dec. 197
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  • 84
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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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  • 85
    Publication Date: 2011-08-16
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; 193; Oct. 1
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  • 86
    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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  • 87
    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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  • 88
    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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  • 89
    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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  • 90
    Publication Date: 2011-08-18
    Keywords: ASTROPHYSICS
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  • 91
    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.
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  • 92
    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
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  • 93
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    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
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  • 94
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    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
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  • 95
    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
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  • 96
    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
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  • 97
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    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
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  • 98
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    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
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  • 99
    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
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  • 100
    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
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