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  • General Chemistry  (4.740)
  • SPACE RADIATION  (1.972)
  • Chemical Engineering  (1.794)
  • STRUCTURAL MECHANICS  (1.510)
  • Cell & Developmental Biology
  • 1970-1974  (10.976)
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  • 101
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    Identification of structural parameters from helicopter dynamic test data (1974)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: 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.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Ames Res. Center Rotorcraft Dyn.; p 239-248
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  • 102
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    Application of antiresonance theory to helicopters (1974)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: 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.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Ames Res. Center Rotorcraft Dyn.; p 101-106
    Format: application/pdf
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  • 103
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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
    Publikationsdatum: 2016-06-07
    Beschreibung: 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.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Ames Res. Center Rotorcraft Dyn.; p 67-80
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  • 104
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    Neutron propagation and 2.2 MeV gamma-ray line production in the solar atmosphere (1974)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: The 2.2 MeV gamma ray line intensity from the sun was calculated using a Monte Carlo method for neutron propagation in the solar atmosphere. Detailed results are provided on the total gamma ray yield per neutron and on the time profile of the 2.2 MeV line from an instantaneous and monoenergetic neutron source. The parameters which have the most significant effects on the line intensity are the energies of the neutrons, the position of the neutron source on the sun, and the abundance of He-3 in the photosphere. For an isotropic neutron source which is not too close to the limb of the sun, the gamma ray yield is between about 0.02 to 0.2 photons per neutron, provided that the neutron energies are in the range 1 to 100 MeV and the ratio He-3/H is less than about .00005.
    Schlagwort(e): SPACE RADIATION
    Materialart: NASA-TM-X-70568 , X-660-74-5
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  • 105
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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
    Publikationsdatum: 2019-06-27
    Beschreibung: 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.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA-TN-D-7346 , A-4966
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  • 106
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    Transverse vibrations of non-uniform beams (1974)
    In:  Other Sources
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: 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.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: Journal of Sound and Vibration; 37; Dec. 22
    Format: text
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  • 107
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    Non-linear behavior of fiber composite laminates (1974)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: 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.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA-CR-2313 , TFR/7309
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  • 108
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    Failure criteria for viscoelastic materials (1974)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: 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.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA-CR-138125 , GALCIT-120
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  • 109
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    Advance development of a technique for characterizing the thermomechanical properties of thermally stable polymers (1974)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: 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.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA-CR-138123
    Format: application/pdf
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  • 110
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    Analysis of laminated, composite, circular cylindrical shells with general boundary conditions (1974)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: 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.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA-TR-R-412 , L-8828
    Format: application/pdf
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  • 111
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    Holographic nondestructive tests performed on composite samples of ceramic-epoxy-fiberglass sandwich structure (1974)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: 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.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA-TR-R-430 , M-461
    Format: application/pdf
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  • 112
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    Procedures for experimental measurement and theoretical analysis of large plastic deformations (1974)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: 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.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA-TM-X-3027 , E-7661
    Format: application/pdf
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  • 113
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    Analysis of three-point-bend test for materials with unequal tension and compression properties (1974)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: 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.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA-TN-D-7572 , E-7544
    Format: application/pdf
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  • 114
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    FORTRAN 4 programs for summarization and analysis of fracture trace and lineament patterns (1974)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: 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.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA-TM-X-70596 , X-644-74-3
    Format: application/pdf
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  • 115
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    The distribution of cosmic rays in the galaxy and their dynamics as deduced from recent gamma-ray observations (1974)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: Recent data from SAS-2 on the galactic gamma ray line flux as a function of longitude reveal a broad maximum in the gamma ray intensity in the region absolute value of l approximately smaller than 30 deg. These data imply that the low energy galactic cosmic ray flux varies with galactocentric distance and is about an order of magnitude higher than the local value in a toroidal region between 4 and 5 kpc from the galactic center. This enhancement can be plausibly accounted for by first order Fermi acceleration, compression and trapping of cosmic rays consistent with present ideas of galactic dynamics and galactic structure theory. Calculations indicate that cosmic rays in the 4 to 5 kpc region are trapped and accelerated over a mean time of the order of a few million years or about 2 to 4 times the assumed trapping time in the solar region of the galaxy.
    Schlagwort(e): SPACE RADIATION
    Materialart: NASA-TM-X-70597 , X-640-74-17
    Format: application/pdf
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  • 116
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    SAS-2 observations of the high energy gamma radiation from the Vela region (1974)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: Data from a scan of the galactic plane by the SAS-B high energy gamma ray experiment in the region 250 deg smaller than 12 smaller than 290 deg show a statistically significant excess over the general radiation from the galactic plane for gamma radiation of energy larger than 100 MeV. If the enhanced gamma radiation results from interactions of cosmic rays with galactic matter, as the energy spectrum suggests, it seems reasonable to associate the enhancement with large scale galactic features, such as spiral arm segments in that direction, or with the region surrounding the Vela supernova remnant with which PSR 0833-45 is associated. If the excess is attributed to cosmic rays released from the supernova interacting with the interstellar matter in that region, than on the order of 3 x 10 to the 50th power ergs would have been released by that supernova in the form of cosmic rays.
    Schlagwort(e): SPACE RADIATION
    Materialart: NASA-TM-X-70602 , X-662-74-58
    Format: application/pdf
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  • 117
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    Sensitivity analysis of torsional vibration characteristics of helicopter rotor blades. Part 2: Aerodynamics and sensitivity analysis (1974)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: 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.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA-CR-2380
    Format: application/pdf
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  • 118
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    Solar cosmic ray composition above 10 MeV/nucleon and its energy dependence in the 4 August 1972 event (1974)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: Observations of the proton, helium (C,N,O) and Fe-group nuclei fluxes made during the large 4 August 1972 solar particle event are presented. The results show a small, but significant variation of the composition of multicharged nuclei as a function of energy in the energy region above 10 MeV/nucleon. In particular, the He/(C,N,O) abundance ratio varies by a factor approximately 2 between 10 and 50 MeV/nucleon, and the Fe-group/(C,N,O) ratio suggests a similar variation. Abundance ratios from the 4 August 1972 event are compared as a function of energy with ratios measured in other solar events. At energies approximately greater than 50 MeV/nucleon, the He/(C,N,O) abundance ratio for August 1972 is consistent with all earlier measurements made above that energy.
    Schlagwort(e): SPACE RADIATION
    Materialart: NASA-TM-X-70590 , X-662-74-32
    Format: application/pdf
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  • 119
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    Measurement of cosmic ray positron and negatron spectra between 50 and 800 MeV (1974)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: A balloon-borne magnetic spectrometer was used to measure the spectra of cosmic ray positrons and negatrons at energies between 50 and 800 MeV. Comparisons of the separate positron and negatron spectra observed near the earth with their expected intensities in interstellar space can be used to investigate the complex (and variable) interaction of galactic cosmic rays with the expanding solar wind. The present measurements, which have established finite values or upper limits for the positron and negatron spectral between 50 and 800 MeV, have confirmed earlier evidence for the existence of a dominant component of negatrons from primary sources in the galaxy. The present results are shown to be consistent with the hypothesis that the positron component is in fact mainly attributable to collisions between cosmic ray nuclei and the interstellar gas. The estimate of the absolute intensities confirm the indications from neutron monitors that in 1972 the interplanetary cosmic ray intensities were already recovering toward their high levels observed in 1965.
    Schlagwort(e): SPACE RADIATION
    Materialart: NASA-TM-X-70580 , X-660-74-16
    Format: application/pdf
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  • 120
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    Assembly and analysis of fragmentation data for liquid propellant vessels (1974)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: 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.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA-CR-134538
    Format: application/pdf
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  • 121
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    Stress anisotropy and concentration effects in high pressure measurements (1974)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: 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.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA-CR-142600 , REPT-2345
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  • 122
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    Elastic moduli of precompressed pyrophyllite used in ultrahigh pressure research (1974)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: The propagation of ultrasonic pulses in pyrophyllite specimens was studied to determine the effect of specimen precompression on the measured elastic moduli. Measurements were made at room pressure and, for the precompressed specimens, to pressures of 3 kbar. Pyrophyllite was found to be elastically anisotropic, apparently the result of the fabric present in our material. The room pressure adiabatic bulk modulus as measured on specimens made of isostatically compacted powered pyrophyllite was determined to be 96.1 kbar. The wave speeds of ultrasonic pulses in pyrophyllite were found to decrease with increasing specimen precompression. A limiting value of precompression was found, above which no further decrease in wave speed was observed. For the shear wave speeds this occurs at 10 kbar while for the longitudinal wave at 25 kbar. In the limit, the shear waves propagate 20% slower than in the unprecompressed samples; for the longitudinal wave the difference is 30%.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA-CR-142598 , REPT-2366
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  • 123
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    Contact and crack problems for an elastic wedge (1974)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: The contact and the crack problems for an elastic wedge of arbitrary angle are considered. The problem is reduced to a singular integral equation which, in the general case, may have a generalized Cauchy kernel. The singularities under the stamp as well as at the wedge apex were studied, and the relevant stress intensity factors are defined. The problem was solved for various wedge geometries and loading conditions. The results may be applicable to certain foundation problems and to crack problems in symmetrically loaded wedges in which cracks initiate from the apex.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA-CR-132640
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  • 124
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    A new model of atmospheric gamma rays and its implications for measurement of diffuse cosmic gamma rays from within the atmosphere (1974)
    In:  Other Sources
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: A semi-empirical model is discussed which describes atmospheric gamma rays in the range 0.3 less then or equal to E less than or equal to 10 MeV based on the production per unit mass of air. The model is based on the concept of a source strength (photon/g sec MeV) which is energy- and depth-dependent, and derived from measured fluxes. Quantities such as directional fluxes, angular distributions, and growth curves are calculated directly from this model. The source function is described by four energy-dependent parameters determined empirically from fluxes measured with a 7.5 cm x 7.5 cm Nal counter over the atmospheric depth range from 3.5 to 500 g/sq cm. From S(E,x), obtained for both continuum and discrete gamma rays at lambda = 40 deg, the depth and angle dependence of directional fluxes were calculated. Growth-curve predictions needed to separate atmospheric from diffuse cosmic fluxes were determined.
    Schlagwort(e): SPACE RADIATION
    Materialart: ESRO The Context and Status of Gamma Ray Astronomy; p 137-145
    Format: text
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  • 125
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    The spectrum of cosmic electron with energies between 6 and 100 GeV (1974)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: This experiment was carried out during three balloon flights which provided a total exposure of 3500 + or - 60 sq m sec sterad at an average depth of 4.8 g/sq cm The detector, in which the development of cascade showers in a 33.7 rl absorber was sampled by 10 scintillation counters and 216 Geiger-Muller tubes, was calibrated at the Cornell Electron Synchrotron, the separation of cosmic electrons from the nuclear background was confirmed by extensive analysis of data from the flights, from the calibration and from ground level exposure. The spectral intensity of primary cosmic ray electrons were found in particles/sq m sec sterad GeV. Similarly, the ground level spectrum of secondary cosmic ray electrons was also found. The steepness of the spectrum of cosmic electrons relative to that of nuclei implies one of the following conclusions: either the injection spectrum of electrons is steeper than that of nuclei, or the electron spectrum has been steepened by Compton/synchrotron losses in the energy range covered by the experiment.
    Schlagwort(e): SPACE RADIATION
    Materialart: NASA-CR-141287 , TR-75-019
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  • 126
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    1-millimeter continuum radiation from Orion Molecular Cloud 2 (1974)
    In:  Other Sources
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: The 1-mm continuum flux from Orion Molecular Cloud 2 (OMC-2), measured with a 1-inch beam, is found to be 0.05 plus or minus 0.01 of that from the Becklin-Neugebauer/Kleinmann-Low (BN/KL) complex. This implies that the average density of dust within OMC-2 is about an order of magnitude less than within the BN/KL region.
    Schlagwort(e): SPACE RADIATION
    Materialart: Astrophysical Journal; 192; Aug. 15
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    A search for X-rays from supernova 1972e with Uhuru and OSO-7 (1974)
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    Publikationsdatum: 2019-06-27
    Beschreibung: The results of observations performed with X-ray detectors aboard OSO-7 and Uhuru at 13 different times ranging from 16 months before to 2 years after Sn 1972e maximum light are reported. Only one possible (3.2 sigma) positive result was found. The absence of any sizable flux contradicts the model of Shklovsky and imposes limitations on the model of Colgate and McKee.
    Schlagwort(e): SPACE RADIATION
    Materialart: Astrophysical Journal; 192; Sept. 1
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  • 128
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    Cosmic-ray streaming perpendicular to the mean magnetic field (1974)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: Starting from a quasi-linear approximation for the ensemble-averaged particle distribution function in a random magnetic field, the complete diffusion tensor is derived. This is done by assuming a simple form for the ensemble-averaged distribution function, explicitly retaining all components of the streaming flux. This derivation obtains the antisymmetric terms in a natural manner. The necessary dropping of higher-order terms gives a criterion for the lower-energy limit of validity of the perpendicular and antisymmetric diffusion coefficients. The limit for the assumed distribution function is about 0.8 GV rigidity in the interplanetary field near 1 AU.
    Schlagwort(e): SPACE RADIATION
    Materialart: Astrophysical Journal; 192; Sept. 1
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  • 129
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    A new model for the high-frequency decametric radiation from Jupiter (1974)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: It is generally accepted that the Jupiter decametric noise bursts occur at frequencies directly related to the electron gyrofrequencies in the Jupiter ionosphere, and it is frequently suggested that the radiation occurs at the gyrofrequency. The recent Pioneer 10 measurement of a 4-G-(R sub 5) cubed dipole moment provides some basis for a more detailed analysis of the local wave mode involved in the radiation. The direct measurement of a relatively small planetary dipole moment suggests that phenomena associated with local ionospheric wave modes having frequencies higher than local gyrofrequencies should be considered for at least some of the emissions. A possible explanation for certain intense high-frequency Jupiter noise bursts is discussed which is based on a wave-wave coupling mechanism that involves the radiation field and the (n + 1/2) gyrofrequency electrostatic modes.
    Schlagwort(e): SPACE RADIATION
    Materialart: NSSDC-ID-68-014A-14-OS , NSSDC-ID-68-014A-24-PS , Journal of Geophysical Research; 79; Sept. 1
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  • 130
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    Measurements of the Jovian radiation belts (1974)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: The University of California at San Diego trapped radiation detector measured proton and electron fluxes, angular distributions, and energy spectra throughout the Pioneer 10 fly by of Jupiter in December 1973. The instrumentation and calibrations are described, and good values for particle fluxes in the inner and outer regions are presented. The major features of the Jovian radiation belts are described, with preliminary discussions of their meanings.
    Schlagwort(e): SPACE RADIATION
    Materialart: Journal of Geophysical Research; 79; Sept. 1
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  • 131
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    Evidence from charged particle studies for the distortion of the Jovian magnetosphere (1974)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: Consideration of the relationship between the rotation of Jupiter's magnetic field and time variations in the intensity of approximately 6- to 30-MeV electrons observed by the University of Chicago experiment on Pioneer 10 in the outer regions of Jupiter's magnetosphere (R greater than 20 Jupiter radii). For R equal to or greater than 40 Jupiter radii the authors' observations are found to be consistent with rigid corotation of the magnetosphere with Jupiter. For R equal to or greater than 40 Jupiter radii, significant deviations from rigid corotation appear with the observed phase of the intensity variations leading the phase expected for rigid corotation on the inbound pass and lagging on the outbound pass. From a different point of view it is found that the time delay between the observed times of intensity minimums and the times expected on the basis of a rigid 9 hour 55 minute period for the intensity variations increased steadily while Pioneer 10 was within the magnetosphere and had reached approximately a ten hour time difference when the spacecraft left the magnetosphere at R approximately equal to 98 Jupiter radii outbound.
    Schlagwort(e): SPACE RADIATION
    Materialart: Journal of Geophysical Research; 79; Sept. 1
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  • 132
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    Ionization mechanisms of the intercloud medium (1974)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: A generalized treatment of the ionization equilibrium of the intercloud medium is developed, which is model-independent in the steady-state approximation, and which is suited to an interpretation of ultraviolet absorption data. It is found that the most satisfactory models require the presence of density inhomogeneities along the line of sight. In all models considered for lambda Sco, 2-MeV cosmic rays and X rays are found to lead to large disagreements with the observations, and data on upsilon Sco, alpha Leo, and other stars seem to support this conclusion. Therefore, it would seem that these cannot be the physical agents responsible for the bulk of the ionization of the gas. An alternative model is developed, in which the ionization below 24.58 eV is provided by ultraviolet photons. This model appears to satisfy theoretical requirements, and leads to good agreement with the data.
    Schlagwort(e): SPACE RADIATION
    Materialart: Astrophysical Journal; 191; July 1
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  • 133
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    Observation of transiron solar-flare nuclei in an Apollo 16 command-module window (1974)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: The first measurements of the fluence of solar particles with nuclear charges not less than 32 and 44 are presented, along with the enhancement factors found. Using a track-etching technique, these transiron nuclei were detected in a window from the Apollo 16 command module which was exposed outside the magnetosphere during the solar-particle event of Apr. 18, 1972.
    Schlagwort(e): SPACE RADIATION
    Materialart: Astrophysical Journal; 190; June 15
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  • 134
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    Decameter type IV bursts associated with coronal transients (1974)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: The characteristics of four moving type IV burst observed with a 65- to 20-MHz swept-frequency interferometer are discussed. All four bursts were associated with depletions in the electron content of the white light corona. Characteristics of the bursts are not unique i.e., they differ in source size, structure, duration, and their association with other radio bursts. Following Smerd and Dulk (1971), it is assumed that a shock wave, moving out from the flare site is responsible for the expansion of a magnetic arch or the ejection of a plasmoid which is observed as the usual type IV burst. Behind the shock wave, the compressed coronal gas moves outward, and as it expands it causes a depletion of electrons in the inner corona. After the passage of the shock wave, sometimes the coronal magnetic field structure is restored to its initial situation, as evidenced by the observation of homologous transients.
    Schlagwort(e): SPACE RADIATION
    Materialart: Solar Physics; 34; Feb. 197
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  • 135
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    Derivatives of eigenvalues and eigenvectors for a general matrix (1974)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: Expressions are obtained for the derivatives of the eigenvalues and eigenvectors which are expressions of only one left-hand and one right-hand eigenvector. The approach described makes use of a Choleski decomposition or some other decomposition method. The method may be extended to find any order of derivative of the eigenvalue and eigenvector. The expressions obtained for finding the derivatives of eigenvalues and eigenvectors for nonself-adjoint systems may be applied to self-adjoint systems.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: AIAA Journal; 12; May 1974
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  • 136
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    A three-dimensional study of 30- to 300-MeV atmospheric gamma rays (1974)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: A three-dimensional study of atmospheric gamma rays with energy greater than 30 MeV has been carried out. A knowledge of these atmospheric secondaries has significant applications to the study of cosmic gamma rays. For detectors carried on balloons, atmospherically produced gamma rays are the major source of background. For satellite detectors, atmospheric secondaries provide a calibration source. Experimental results were obtained from four balloon flights from Palestine, Texas, with a 15 cm by 15 cm digitized wire grid spark chamber. The energy spectrum for downward-moving gamma rays steepens with increasing atmospheric depth. Near the top of the atmosphere, the spectrum steepens with increasing zenith angle. A new model of atmospheric secondary production has calculated the depth, the energy, and the zenith angle dependence of gamma rays above 30 MeV, using a comprehensive three-dimensional Monte Carlo model of the nucleon-meson-electromagnetic cascade.
    Schlagwort(e): SPACE RADIATION
    Materialart: Journal of Geophysical Research; 79; Apr. 1
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  • 137
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    Mariner 6, 7, and 9 ultraviolet spectrometer experiment - Analysis of hydrogen Lyman alpha data (1974)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: Four Lyman alpha airglow measurements of the limb and disk of Mars, made by ultraviolet spectrometers on Mariner 6 and 7 in 1969 and Mariner 9 in 1971, are analyzed to determine the amount and distribution of atomic hydrogen above 80 km. The variation of atomic hydrogen with altitude is calculated by using time-independent chemical diffusion models from 80 to 250 km, and an exospheric model is used above 250 km. By employing radiative transfer theory that includes effects of pure absorption and accounts for temperature variations in the atmosphere, a spherical model of the airglow Lyman alpha emission is used to produce theoretical intensities for comparison with the data. It is found that (1) the exospheric temperature and distribution in 1971 are consistent with those determined in 1969, (2) the vertical optical depth above 80 km was 2.2 in 1969 and 5 in 1971, and (3) the derived atomic hydrogen distribution from 80 to 250 km requires a source of atomic hydrogen above 80 km. Comparison of observed profiles with chemical diffusion models implies a large downward flow of atomic hydrogen at 80 km coupled with a large upward flow of molecular hydrogen.-
    Schlagwort(e): SPACE RADIATION
    Materialart: Journal of Geophysical Research; 79; Apr. 1
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  • 138
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    An experimental-theoretical study of free vibrations of plates on elastic point supports (1974)
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    Publikationsdatum: 2019-06-27
    Beschreibung: A theoretical and experimental study is made to investigate the effect on plate vibrations of varying the stiffness of corner elastic point supports. An experiment is conducted in which the bending stiffness of horizontal beams is used to support a square plate at its four corners. The stiffness of these supports can be varied over such a range that the plate fundamental frequency is lowered to 40% of the rigid support frequency. The variation with support stiffness of the frequencies of the first eight plate modes is measured and is compared with results from a theoretical model in which a Rayleigh-Ritz analysis is used which approximates the plate mode shapes as products of free-free beam modes. The elastic point supports are modeled both as massless translational springs and springs with tip masses, which are included to better represent the experimental supports.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: Journal of Sound and Vibration; 32; Feb. 22
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  • 139
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    Cosmic ray scintillations. II - General theory of interplanetary scintillations (1974)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: The motion of charged particles in a stochastic magnetic field with nonzero mean is considered via a generalized quasi-linear expansion of Liouville's equation. The general result is an equation relating cosmic ray scintillations to magnetic fluctuations and to cosmic ray gradients. The resonant interaction between particles and the random magnetic field is considered in detail, and the effect of nonlinear terms in the equations is considered. The nonlinear terms are important in damping out initial conditions and in determining conditions near cyclotron resonances. The application of the theory to the propagation of cosmic rays during quiet times in interplanetary space is considered. It is concluded that cosmic ray scintillations in interplanetary space may provide useful information about interplanetary particles and fields and also about nonlinear plasma interactions.
    Schlagwort(e): SPACE RADIATION
    Materialart: Journal of Geophysical Research; 79; Mar. 1
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  • 140
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    Design manual: Oxygen Thermal Test Article (OTTA) (1974)
    In:  CASI
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    Publikationsdatum: 2019-06-27
    Beschreibung: The characteristics of a cryogenic tank for storing liquid hydrogen, nitrogen, oxygen, methane, or helium for an extended period of time with minimum losses are discussed. A description of the tank and control module, assembly drawings and details of major subassemblies, specific requirements controlling development of the system, thermal concept considerations, thermal analysis methods, and a record of test results are provided. The oxygen thermal test article thermal protection system has proven that the insulation system for cryogenic vessels is effective.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA-CR-140209 , ER15961
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  • 141
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    Research on the elastic stability of large shells (1974)
    In:  CASI
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    Publikationsdatum: 2019-06-27
    Beschreibung: Tests were conducted to determine the elastic stability of large shell structures. The configuration of the shells and the instrumentation used in the measurements are described. The testing procedures are explained. Results of the stress analysis are plotted in polar graph form to show the areas of strain in micro inches at the outer surface of the skin and the inner lip of the stringer.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA-CR-139665 , SAPR-6
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  • 142
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    Method and apparatus for decoding compatible convolutional codes (1974)
    In:  CASI
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    Publikationsdatum: 2019-06-27
    Beschreibung: This invention relates to learning decoders for decoding compatible convolutional codes. The decoder decodes signals which have been encoded by a convolutional coder and allows performance near the theoretical limit of performance for coded data systems. The decoder includes a sub-bit shift register wherein the received sub-bits are entered after regeneration and shifted in synchronization with a clock signal recovered from the received sub-bit stream. The received sub-bits are processed by a sub-bit decision circuit, entered into a sub-bit shift register, decoded by a decision circuit, entered into a data shift register, and updated to reduce data errors. The bit decision circuit utilizes stored sub-bits and stored data bits to determine subsequent data-bits. Data errors are reduced by using at least one up-date circuit.
    Schlagwort(e): STRUCTURAL MECHANICS
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  • 143
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    Causes of forbush decreases and other cosmic ray variations (1974)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: The relationship between neutron monitor variations and the intensity variations of the interplanetary magnetic field is studied, using Deep River data and IMP-series satellite data. In over 80% of the cases studied, identifiable depressions of the cosmic ray intensity are associated with magnetic field enhancements of several hours duration and intensity above 10 gamma. Conversely, each magnetic field enhancement has an identifiable effect (though not necessarily a marked depression) on the cosmic ray intensity. Long lasting Forbush decreases are found to be the consequence of the successive action of several such features. An explanation is presented and discussed.
    Schlagwort(e): SPACE RADIATION
    Materialart: NASA-TM-X-70726 , X-690-74-224
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  • 144
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    Heavy solar cosmic rays in the January 25, 1971 solar flares (1974)
    In:  CASI
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    Publikationsdatum: 2019-06-27
    Beschreibung: A detailed study of the charge composition of heavy solar cosmic rays measured in the January 25, 1971 solar flare including differential fluxes for the even charged nuclei from carbon through argon is presented. The measurements are obtained for varying energy intervals for each nuclear species in the energy range from 10 to 35 MeV/nucleon. In addition, abundances relative to oxygen are computed for all the above nuclei in the single energy interval from 15 to 25 MeV/nucleon. This interval contains measurements for all of the species and as a result requires no spectral extrapolations. An upper limit for the abundance of calcium nuclei is also presented. These measurements, when combined with other experimental results, enable the energy dependence of abundance measurements as a function of nuclear charge to be discussed. It is seen that at energies above about 10 MeV/nucleon, the variations of abundance ratios are limited to about a factor of 3 from flare to flare, in spite of large variations in other characteristics of these solar events.
    Schlagwort(e): SPACE RADIATION
    Materialart: NASA-TM-X-70731 , X-662-74-231
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  • 145
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    Temperature dependence of emission measure in solar X-ray plasmas. 1: Non-flaring active regions (1974)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: X-ray and ultraviolet line emission from hot, optically thin material forming coronal active regions on the sun may be described in terms of an emission measure distribution function, Phi (T). A relationship is developed between line flux and Phi (T), a theory which assumes that the electron density is a single-valued function of temperature. The sources of error involved in deriving Phi (T) from a set of line fluxes are examined in some detail. These include errors in atomic data (collisional excitation rates, assessment of other mechanisms for populating excited states of transitions, element abundances, ion concentrations, oscillator strengths) and errors in observed line fluxes arising from poorly - known instrumental responses. Two previous analyses are discussed in which Phi (T) for a non-flaring active region is derived. A least squares method of Batstone uses X-ray data of low statistical significance, a fact which appears to influence the results considerably. Two methods for finding Phi (T) ab initio are developed. The coefficients are evaluated by least squares. These two methods should have application not only to active-region plasmas, but also to hot, flare-produced plasmas.
    Schlagwort(e): SPACE RADIATION
    Materialart: NASA-TM-X-70725 , X-682-74-220
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  • 146
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    Two high resolution velocity vector analyzers for cosmic dust particles (1974)
    In:  CASI
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    Publikationsdatum: 2019-06-27
    Beschreibung: Methods are described to measure velocities and angles of incidence of charged cosmic dust particles with precisions of about 1 percent and 1 degree, respectively. Both methods employ four one-dimensional position-sensitive detectors in series. The first method utilizes a charge-dividing technique while the second utilizes a time-of-flight technique for determining the position of a particle inside the instrument. The velocity vectors are measured although mechanical interaction between the particle and the instrument is completely avoided. Applications to cosmic dust composition and collection experiments are discussed. The range of radii of measurable particles is from about 0.01 to 100 microns at velocities from 1 to 80 km/s.
    Schlagwort(e): SPACE RADIATION
    Materialart: NASA-TM-X-70727 , X-672-74-226
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  • 147
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    Ultrasonic measurement of stress in railroad wheels and in long lengths of welded rail (1974)
    In:  CASI
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    Publikationsdatum: 2019-06-27
    Beschreibung: The failure of high speed emergency braking is discussed for railroad wheels and track. It is shown that high compressive residual stresses exist in the rims of new wheels which generate excessive heat, reducing the stress levels. Thermal stresses that build up in continuous lengths of welded track are reported and nondestructive methods of measuring stresses in thick steel are presented for identification, replacement, or adjustment before hazardous failures occur.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA-TM-X-64863
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  • 148
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    Evaluation of a metal shear web selectively reinforced with filamentary composites for space shuttle application (1974)
    In:  CASI
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    Publikationsdatum: 2019-06-27
    Beschreibung: A final program summary is reported for test and evaluation activities that were conducted for space shuttle web selection. Large scale advanced composite shear web components were tested and analyzed to evaluate application of advanced composite shear web construction to a space shuttle orbiter thrust structure. The shear web design concept consisted of a titanium-clad + or - 45 deg boron/epoxy web laminate stiffened with vertical boron-epoxy reinforced aluminum stiffeners and logitudinal aluminum stiffening. The design concept was evaluated to be efficient and practical for the application that was studied. Because of the effects of buckling deflections, a requirement is identified for shear buckling resistant design to maximize the efficiency of highly-loaded advanced composite shear webs.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA-CR-2409 , D180-17969-1
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  • 149
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    Solar cycle variation of large-scale coronal structures (1974)
    In:  CASI
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    Publikationsdatum: 2019-06-27
    Beschreibung: A green line intensity variation is associated with the interplanetary and photospheric magnetic sector structure. This effect depends on the solar cycle and occurs with the same amplitude in the latitude range 60 deg N - 60 deg S. Extended longitudinal coronal structures are suggested, which indicate the existence of closed magnetic field lines over the neutral line, separating adjacent regions of opposite polarities on the photospheric surface.
    Schlagwort(e): SPACE RADIATION
    Materialart: NASA-CR-139500 , SU-IPR-569
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  • 150
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    Solar rotating magnetic dipole? (1974)
    In:  CASI
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    Publikationsdatum: 2019-06-27
    Beschreibung: A magnetic dipole rotating around an axis perpendicular to the rotation axis of the sun can account for the characteristics of the surface large-scale solar magnetic fields through the solar cycle. The polarity patterns of the interplanetary magnetic field, predictable from this model, agree with the observed interplanetary magnetic sector structure.
    Schlagwort(e): SPACE RADIATION
    Materialart: NASA-CR-139501 , SU-IPR-570
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  • 151
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    The spiral interplanetary magnetic field: A polarity and sunspot cycle variation (1974)
    In:  CASI
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    Publikationsdatum: 2019-06-27
    Beschreibung: Spacecraft observations near the earth of the yearly average direction of the interplanetary magnetic field during the sunspot maximum year 1968 showed a deviation from the spiral field. The angle between the average field direction when the field polarity was away from the sun and the average direction for toward polarity was 168 deg, rather than 180 deg. This effect appears to have a sunspot cycle variation.
    Schlagwort(e): SPACE RADIATION
    Materialart: NASA-CR-139499 , SU-IPR-573
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  • 152
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    Radial gradient of solar wind velocity from 1 to 5 AU (1974)
    In:  CASI
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    Publikationsdatum: 2019-06-27
    Beschreibung: Solar wind velocities have been measured on a daily basis from data obtained by the Ames Research Center plasma analyzers on both Pioneer 10 and Pioneer 11. A comparison between the time profiles of the solar wind velocities observed at the two spacecraft shows that the solar wind has the same major features, such as high velocity streams, out to at least 5 astronomical units (AU) from the sun. Major features in the velocity time profile observed first at Pioneer 11 are seen later at Pioneer 10 with a delay consistent with the respective heliocentric longitudes of the two spacecraft, their radial distances from the sun, and the solar wind velocity. A more detailed comparison between the velocity measurements made at Pioneer 10 and Pioneer 11 shows that the range of solar wind velocities decreases with increasing radial distance from the sun. Although the average value of the solar wind velocity as measured over a sufficiently long period is approximately the same at both spacecraft, the deviations to higher and lower velocities are less at a greater radial distance from the sun.
    Schlagwort(e): SPACE RADIATION
    Materialart: NASA-TM-X-62372
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  • 153
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    Digital communication system (1974)
    In:  CASI
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    Publikationsdatum: 2019-06-27
    Beschreibung: A digital communication system is reported for parallel operation of 16 or more transceiver units with the use of only four interconnecting wires. A remote synchronization circuit produces unit address control words sequentially in data frames of 16 words. Means are provided in each transceiver unit to decode calling signals and to transmit calling and data signals. The transceivers communicate with each other over one data line. The synchronization unit communicates the address control information to the transceiver units over an address line and further provides the timing information over a clock line. A reference voltage level or ground line completes the interconnecting four wire hookup.
    Schlagwort(e): STRUCTURAL MECHANICS
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  • 154
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    Coherent receiver employing nonlinear coherence detection for carrier tracking (1974)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: The concept of nonlinear coherence employed in carrier tracking to improve telecommunications efficiency is disclosed. A generic tracking loop for a coherent receiver is shown having seven principle feedback signals which may be selectively added and applied to a voltage controlled oscillator to produce a reference signal that is phase coherent with a received carrier. An eighth feedback signal whose nonrandom components are coherent with the phase detected and filtered carrier may also be added to exploit the sideband power of the received signal. A ninth feedback signal whose nonrandom components are also coherent with the quadrature phase detected and filtered carrier could be additionally or alternatively included in the composite feedback signal to the voltage controlled oscillator.
    Schlagwort(e): STRUCTURAL MECHANICS
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  • 155
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    On thermal stress failure of the SNAP-19A RTG heat shield (1974)
    In:  CASI
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    Publikationsdatum: 2019-06-27
    Beschreibung: Results of a study on thermal stress problems in an amorphous graphite heat shield that is part of the launch-abort protect system for the SNAP-19A radio-isotope thermoelectric generators (RTG) that will be used on the Viking Mars Lander are presended. The first result is from a thermal stress analysis of a full-scale RTG heat source that failed to survive a suborbital entry flight test, possibly due to thermal stress failure. It was calculated that the maximum stress in the heat shield was only 50 percent of the ultimate strength of the material. To provide information on the stress failure criterion used for this calculation, some heat shield specimens were fractured under abort entry conditions in a plasma arc facility. It was found that in regions free of stress concentrations the POCO graphite heat shield material did fracture when the local stress reached the ultimate uniaxial stress of the material.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA-TM-X-3097 , A-5516
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  • 156
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    Stress intensity factors for deep cracks emanating from the corner formed by a hole intersecting a plate surface (1974)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: A technique consisting of freezing photo-elasticity and a numerical method was used to obtain stress intensity factors for natural cracks emanating from the corner at which a hole intersects a plate surface. Geometries studied were: (1) crack depth to thickness ratios of approximately 0.2, (2) 0.5 and 0.75; (3) crack depth to crack length ratios of approximately 1.0 to 2.0; and (4) crack length to hole radius ratios of about 0.5 to 2.0. All final crack geometries were grown under monotonic loading and growth was not self similar, with most of the growth occuring through the thickness under remote extension. Stress intensity factors were determined at the intersection of the flaw border.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA-CR-132484 , VPI-E-74-1-REV
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  • 157
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    Application of a substructuring technique to the problem of crack extension and closure (1974)
    In:  CASI
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    Publikationsdatum: 2019-06-27
    Beschreibung: A substructuring technique, originally developed for the efficient reanalysis of structures, is incorporated into the methodology associated with the plastic analysis of structures. An existing finite-element computer program that accounts for elastic-plastic material behavior under cyclic loading was modified to account for changing kinematic constraint conditions - crack growth and intermittent contact of crack surfaces in two dimensional regions. Application of the analysis is presented for a problem of a centercrack panel to demonstrate the efficiency and accuracy of the technique.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA-CR-132458 , RE-480
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  • 158
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    Deformation characteristics and time-dependent notch sensitivity of Udimet 700 at intermediate temperatures (1974)
    In:  CASI
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    Publikationsdatum: 2019-06-27
    Beschreibung: Time dependent notch sensitivity was observed in Udimet 700 sheet, bar, and investment castings between 1000 and 1400 F (538 -760 C), but not at 1600 F (871 C). As was the case for modified Waspaloy, Waspaloy and Inconel 718, it occurred in notched specimens loaded below the yield strength when the creep deformation was localized. For each alloy and notched specimen geometry, a stress-average particle size zone can be defined that characterizes the notch sensitive behavior.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA-CR-134613 , REPT-043680-20-F
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  • 159
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    Analysis of wing-body interaction flutter for a preliminary space shuttle design (1974)
    In:  CASI
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    Publikationsdatum: 2019-06-27
    Beschreibung: Subsonic flutter analyses for a preliminary space shuttle design were performed to determine the effect of wing-body aerodynamic interaction on the vehicle flutter speed. It was found that the proximity of the large bodies of the shuttle to the wing reduces critical flutter speed by 11%. Aerodynamic reflection off the bodies is the dominant interaction effect while aerodynamic forces caused by body motion are of secondary importance in most cases. The analyses employed a doublet-lattice representation of the space shuttle, where in the wing and body surfaces were modeled by a lattice of nonplanar lifting surface elements. Axial singularities were introduced to account for body incidence, volume, and camber (slender body) effects. A series of studies on the placement and number of these elements was performed to ensure convergence of the results.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA-CR-2429
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  • 160
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    Analysis of complex elastic structures by a Rayleigh-Ritz component modes method using Lagrange multipliers (1974)
    In:  CASI
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    Publikationsdatum: 2019-06-27
    Beschreibung: The free vibrations of elastic structures of arbitrary complexity were analyzed in terms of their component modes. The method was based upon the use of the normal unconstrained modes of the components in a Rayleigh-Ritz analysis. The continuity conditions were enforced by means of Lagrange Multipliers. Examples of the structures considered are: (1) beams with nonuniform properties; (2) airplane structures with high or low aspect ratio lifting surface components; (3) the oblique wing airplane; and (4) plate structures. The method was also applied to the analysis of modal damping of linear elastic structures. Convergence of the method versus the number of modes per component and/or the number of components is discussed and compared to more conventional approaches, ad-hoc methods, and experimental results.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA-CR-138942 , AMS-1159
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  • 161
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    Energetic solar proton versus terrestrially trapped proton fluxes for the active years 1977 - 1983 (1974)
    In:  CASI
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    Publikationsdatum: 2019-06-27
    Beschreibung: Ratios of solar to trapped proton fluences were computed for circular-orbit, geocentric space missions to be flown during the active phase of the next solar cycle (1977-1983). The ratios are presented as functions of orbit altitude and inclination, mission duration, proton energy threshold, and the chance the mission planner is willing to take that the actually encountered solar proton fluence will exceed the design fluence provided by the statistical solar proton model. It is shown that the ratio is most sensitively dependent on orbit altitude and inclination, with trapped protons dominant for low inclination, low and mid altitude orbits and for high inclination, mid altitude orbits. Conversely, solar protons are dominant for high inclination, low altitude orbits, and for low and high inclination, high altitude orbits.
    Schlagwort(e): SPACE RADIATION
    Materialart: NASA-TM-X-70716 , X-601-74-221
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  • 162
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    Interplantetary streams and their interaction with the earth (1974)
    In:  CASI
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    Publikationsdatum: 2019-06-27
    Beschreibung: Plasma and magnetic field observations of interplanetary streams near 1 AU are summarized. Two types of streams have been identified corotating streams and flare-associated, and other flow patterns are present due to interactions among streams. The theory of corotating streams, which attributes them to a high temperature region near the sun, satisfactorily explains many of the effects observed at 1 AU. A correspondingly complete theory of flare-associated streams does not exist. Streams are a key link in the chain that connects solar and geomagnetic activity. The factors that most influence geomagnetic activity are probably related to streams and determined by the dynamics of streams. The evolution of streams on scales of 27 days and 11 years probably determines the corresponding variations of geomagnetic activity.
    Schlagwort(e): SPACE RADIATION
    Materialart: NASA-TM-X-70714 , X-692-74-216
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  • 163
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    Trapped particle and solar proton radiation prediction for ISEE (IME): Mother-daughter mission (1974)
    In:  CASI
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    Publikationsdatum: 2019-06-27
    Beschreibung: The charged particle fluxes incident on spacecrafts in very eccentric orbits were investigated in support of the International Sun-Earth Explorer (International Magnetospheric Explorer) For this purpose, two flightpaths were considered having identical inclinations but different perigee altitudes (240 and 1364 kilometers, respectively). Apogee altitude was approximately the same for both cases (about 22 earth radii). For each of the two perigee altitudes investigated, two nominal trajectories were generated, having identical orbital configurations but with their major axes rotated by 180 deg in the plane of orbit, which resulted in placing the initial apogee into into opposite hemispheres. This was done in order to determine the corresponding variation in the vehicle-encountered particle intensities. Estimates of average energetic solar proton fluxes are given for a one year mission duration at selected integranlenergies ranging from E 10 to E 100 MeV. Results are summarized and discussed.
    Schlagwort(e): SPACE RADIATION
    Materialart: NASA-TM-X-70696 , X-601-74-204
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  • 164
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    Rotation in vibration, optimization, and aeroelastic stability problems (1974)
    In:  CASI
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    Publikationsdatum: 2019-06-27
    Beschreibung: The effects of rotation in the areas of vibrations, dynamic stability, optimization, and aeroelasticity were studied. The governing equations of motion for the study of vibration and dynamic stability of a rapidly rotating deformable body were developed starting from the nonlinear theory of elasticity. Some common features such as the limitations of the classical theory of elasticity, the choice of axis system, the property of self-adjointness, the phenomenon of frequency splitting, shortcomings of stability methods as applied to gyroscopic systems, and the effect of internal and external damping on stability in gyroscopic systems are identified and discussed, and are then applied to three specific problems.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA-CR-138805
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  • 165
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    Midlatitude electron precipitation: A possible source of contamination of galactic X and gamma-ray measurements (1974)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: The effect of trapped and precipitated particles in the magnetosphere on the measurement of galactic X-rays and gamma rays is discussed. To minimize contamination caused by electron precipitation, most galactic X-ray and gamma ray measurements are conducted at equatorial or relatively low to middle latitudes where the influence of auroral effects is expected to be small. Substorm-related VLF phase perturbations also affect the measurements. If such perturbation are indicative of electron precipitation at middle to low latitudes, then their relatively high frequency of occurrence, as many as 100 per year, is evidence that electron precipitation at these latitudes may pose a problem to some galactic X-ray and gamma ray measurements. Charts and maps are presented to show: (1) phase recordings from sixteen sub-ionospheric VLF propagation paths, (2) map of great circle propagation paths, (3) ionization rates in the nighttime ionosphere due to several sources, and (4) computer phase variation for the NLK-APL path versus electron flux for different e-folding energies.
    Schlagwort(e): SPACE RADIATION
    Materialart: NASA. Goddard Space Flight Center Proc. of the Workshop on Electron Contamination in X-ray Astronomy Expt.; 14 p
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  • 166
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    Coordinate transformations for studies of interactions between interplanetary and geomagnetic fields (1974)
    In:  CASI
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    Publikationsdatum: 2019-06-27
    Beschreibung: A graphical procedure is provided for performing coordinate transformations between the geocentric-solar-equatorial, geocentric-solar-ecliptic and geocentric-solar-magnetospheric coordinate systems. The procedure is designed to facilitate intercomparison of previous studies of interactions between interplanetary and geomagnetic fields that made use of these coordinate systems. The interaction in the geocentric-solar-magnetosphere system has been shown to give the most consistent results.
    Schlagwort(e): SPACE RADIATION
    Materialart: NASA-TM-X-70684 , X-621-74-179
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  • 167
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    Technique for recovery of voice data from heat damaged magnetic tape (1974)
    In:  CASI
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    Publikationsdatum: 2019-06-27
    Beschreibung: A method for conditioning, and thus enabling retrieval of intelligence from, magnetic tapes after damage from heat has caused the tape to wrinkle and curl severely thereby reducing tape width to less than one-half its original size. The damaged tape is superposed on a first piece of splicing tape with the oxide side of the magnetic tape in contact with the adhesive side of the splicing tape and then carefully smoothed by a special tool. A second piece of splicing tape is placed on the backing side of the magnetic tape then the resulting tape stack is trimmed to the original width of the magnetic tape. After the first piece of splicing tape is carefully removed from the oxide side of the damaged magnetic tape, the resulting magnetic tape is then ready to be placed into a recorder for playback.
    Schlagwort(e): STRUCTURAL MECHANICS
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  • 168
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    Gravitational-wave bursts from the nuclei of distant galaxies and quasars: Proposal for detection using Doppler tracking of interplanetary spacecraft (1974)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: Supermassive black holes which exist in the nuclei of many quasars and galaxies are examined along with the collapse which forms these holes and subsequent collisions between them which produce strong, broad-band bursts of gravitational waves. Such bursts might arrive at earth as often as 50 times per year--or as rarely as once each 300 years. The detection of such bursts with dual-frequency Doppler tracking of interplanetary spacecraft is considered.
    Schlagwort(e): SPACE RADIATION
    Materialart: NASA-CR-145432
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  • 169
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    SAS-2 observations of the galactic gamma radiation from the Vela region (1974)
    In:  CASI
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    Publikationsdatum: 2019-06-27
    Beschreibung: Data from a scan of the galactic plane by the SAS-2 high energy gamma ray experiment in the region 250 deg l2 290 deg show a statistically-significant excess over the general radiation from the galactic plane for gamma radiation of energy 100 MeV in the region 260 deg l2 270 deg and -7.5 deg b2 0 deg. If the enhanced gamma radiation results from interactions of cosmic rays with galactic matter, as the energy spectrum suggests, it seems reasonable to associate the enhancement with large scale galactic features, such as spiral arm segments in that direction, or with the region surrounding the Vela supernova remnant, with which PSR 0833-45 is associated. If the excess is attributed to cosmic rays released from this supernova interacting with the interstellar matter in that region, then on the order of 3.10 to the 50th power ergs would be released by that supernova in the form of cosmic rays.
    Schlagwort(e): SPACE RADIATION
    Materialart: NASA-TM-X-72582
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  • 170
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    A numerically efficient finite element hydroelastic analysis. Volume 2: Implementation in NASTRAN, part 2 (1974)
    In:  CASI
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    Publikationsdatum: 2019-06-27
    Beschreibung: For abstract, see N76-13529.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA-CR-132684-VOL-2-PT-2
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  • 171
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    A numerically efficient finite element hydroelastic analysis. Volume 2: Implementation in NASTRAN, part 1 (1974)
    In:  CASI
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    Publikationsdatum: 2019-06-27
    Beschreibung: Details are presented of the implementation of the new formulation into NASTRAN including descriptions of the DMAP statements required for conversion of the program and details pertaining to problem definition and bulk data considerations. Details of the current 1/8-scale space shuttle external tank mathematical model, numerical results and analysis/test comparisons are also presented. The appendices include a description and listing of a FORTRAN program used to develop harmonic transformation bulk data (multipoint constraint statements) and sample bulk data information for a number of hydroelastic problems.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA-CR-132684-VOL-2-PT-1
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  • 172
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    Theory of buckling and post-buckling behavior of elastic structures (1974)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: The present paper provides a unified, general presentation of the basic theory of the buckling and post-buckling behavior of elastic structures in a form suitable for application to a wide variety of special problems. The notation of functional analysis is used for this purpose. Before the general analysis, simple conceptual models are used to elucidate the basic concepts of bifurcation buckling, snap buckling, imperfection sensitivity, load-shortening relations, and stability. The energy approach, the virtual-work approach, and mode interaction are discussed. The derivations and results are applicable to continua and finite-dimensional systems. The virtual-work and energy approaches are given separate treatments, but their equivalence is made explicit. The basic concepts of stability occupy a secondary position in the present approach.
    Schlagwort(e): STRUCTURAL MECHANICS
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  • 173
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    Plastic buckling (1974)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: The present article is concerned mainly with the post-bifurcation and imperfection-sensitivity aspects of plastic buckling. A simple two-degree-of-freedom model is used to introduce post-bifurcation behavior and a second model illustrates features of the behavior of continuous solids and structures. Hill's bifurcation criterion for a class of three-dimensional solids is applied to the Donnell-Mushtari-Vlasov (DMV) theory of plates and shells. A general treatment of the initial post-bifurcation behavior of plates and shells is given within the context of the DMV theory. This is illustrated by problems involving columns and circular plates under radial compression. Numerical results are given for a column under axial compression, a circular plate under radial compression, and spherical and cylindrical shells.
    Schlagwort(e): STRUCTURAL MECHANICS
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  • 174
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    Three-dimensional growth characteristics of a plane crack subjected to concentrated forces (1974)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: A combination of longitudinal shear and normal forces acting on a half-plane crack is shown to lead to predictions of crack growth qualitatively similar to those obtained by Knauss (1970) for crack propagation in antiplane shear. The presented results, based on the strain-energy-density fracture criterion, predict the direction of growth and the load which initiates it.
    Schlagwort(e): STRUCTURAL MECHANICS
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  • 175
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    Thermoelastic constitutive equations for chemically hardening materials (1974)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: Thermoelastic constitutive equations are derived for a material undergoing solidification or hardening as the result of a chemical reaction. The derivation is based upon a two component model whose composition is determined by the degree of hardening, and makes use of strain-energy considerations. Constitutive equations take the form of stress rate-strain rate relations, in which the coefficients are time-dependent functions of the composition. Specific results are developed for the case of a material of constant bulk modulus which undergoes a transition from an initial liquidlike state into an isotropic elastic solid. Potential applications are discussed.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: ASME PAPER 74-WA/APM-7
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  • 176
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    Steady-state solution to the conduction problem of a spherical balloon radiometer, phases 1 and 2 (1974)
    In:  CASI
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    Publikationsdatum: 2019-06-27
    Beschreibung: A satellite system proposed for observing the earth's radiation balance employing spherical balloon radiometers is investigated. In the steady-state condition of radiative equilibrium, the magnitudes of absorbed external irradiances are sensed by internal radiometers mounted on the skin of each balloon. The temperatures of the radiometers are monitored as a measure of the balloons' internal irradiances (equal to absorbed external irradiances) and telemetered to earth. The effect of the magnitude of irradiant sources, balloon thickness, and thermal conductivity on the conduction of heat is assessed mathematically in order to determine its impact on measurement accuracy. Results indicate that observations are acceptable during daytime and nighttime modes of operation.
    Schlagwort(e): SPACE RADIATION
    Materialart: NASA-CR-132624
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  • 177
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    An investigation of ESSA 7 radiation data for use in long-term earth energy experiments, phases 1 and 2 (1974)
    In:  CASI
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    Publikationsdatum: 2019-06-27
    Beschreibung: The results are presented of an investigation of ESSA 7 satellite radiation data for use in long-term earth energy experiments. Satellite systems for performing long-term earth radiation balance measurements over geographical areas, hemispheres, and the entire earth for periods of 10 to 30 years are examined. The ESSA 7 satellite employed plate and cone radiometers to measure earth albedo and emitted radiation. Each instrument had a black and white radiometer which discriminated the components of albedo and emitted radiation. Earth measurements were made continuously from ESSA 7 for ten months. The ESSA 7 raw data is processed to a point where it can be further analyzed for: (1) development of long-term earth energy experiments; and (2) document climate trends.
    Schlagwort(e): SPACE RADIATION
    Materialart: NASA-CR-132623
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  • 178
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    Pitch-angle scattering of charged particles in a random magnetic field (1974)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: A calculation is presented in terms of the pitch angle that determines the conditions under which a Fokker-Planck equation gives a reasonable approximation of the pitch-angle scattering of low rigidity particles to first order in a random magnetic field. The formulation shows that the correlation scale of the fluctuation of the magnetic field about its mean does not enter directly into the approximation. The calculation is carried out for transverse magnetic fluctuations for which the magnetic field magnitude is constant to the order considered.
    Schlagwort(e): SPACE RADIATION
    Materialart: Astrophysical Journal; 194; Dec. 1
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  • 179
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    Cross correlation between cosmic-ray fluctuations and interplanetary magnetic-field fluctuations (1974)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: Study of the cross-correlation between cosmic-ray intensity fluctuations and the interplanetary magnetic field, using the low-frequency limit of the theory of the interplanetary scintillations of cosmic rays. Cross-spectral analysis of the flux of the Alert neutron monitor and simultaneous values of the interplanetary magnetic field components are presented which support the theory. A model of cosmic-ray fluctuations is described, with effects of gradients and interplanetary sector structure dominating for very low frequencies (less than or about equal to .000005 Hz) and magnetic-field induced interplanetary scintillations of cosmic rays dominating for higher frequencies.
    Schlagwort(e): SPACE RADIATION
    Materialart: Geophysical Research Letters; 1; Dec. 197
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  • 180
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    Reanalysis information for eigenvalues derived from a differential equation analysis formulation (1974)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: The investigation reported demonstrates that in the case considered perturbation methods can be used in a straightforward manner to obtain reanalysis information. A perturbation formula for the buckling loads of a general shell of revolution is derived. The accuracy of the obtained relations and their range of application is studied with the aid of a specific example involving a particular stiffened shell of revolution.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: AIAA Journal; 12; Dec. 197
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  • 181
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    The comparative spectra of cosmic-ray protons and helium nuclei (1974)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Schlagwort(e): SPACE RADIATION
    Materialart: Astrophysics and Space Science; 30; Oct. 197
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  • 182
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    A stiffness derivative finite element technique for determination of crack tip stress intensity factors (1974)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: A finite element technique for determination of elastic crack tip stress intensity factors is presented. The method, based on the energy release rate, requires no special crack tip elements. Further, the solution for only a single crack length is required, and the crack is 'advanced' by moving nodal points rather than by removing nodal tractions at the crack tip and performing a second analysis. The promising straightforward extension of the method to general three-dimensional crack configurations is presented and contrasted with the practical impossibility of conventional energy methods.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: International Journal of Fracture; 10; Dec. 197
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  • 183
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    A note on the interference of two collinear cracks in a cylindrical shell (1974)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: A simple interference problem in shells is evaluated and the results are compared with the obtained data for flat plates. A pressurized shallow cylindrical shell containing two collinear axial through cracks of equal lengths is investigated. It is found that as the size of the net ligament between the two cracks approaches zero, the stress intensity factors at the inner crack tips go to infinity, and the factors at the outer tips approach values that correspond to a single crack except that they are twice as long.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: International Journal of Fracture; 10; Dec. 197
    Format: text
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  • 184
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    Cosmic ray anisotropies observed late in the decay phase of solar flare events (1974)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: Data was obtained from instrumentation on Explorers 34 and 41 on cosmic-ray anisotropy and magnetic field vectors during five solar flare events. The analysis was conducted in the energy range from 0.7 to 7.6 MeV, of the late decay phase, to evaluate the dependence of net cosmic-ray anisotropy vector amplitude and direction on the magnetic field azimuth. Results showed that in the late decay phase the direction of the net cosmic-ray anisotropy vector was invariant in relation to the direction of the magnetic field, particle energy, and species. Within the statistical error of the available data the invariant direction was perpendicular to the mean magnetic field direction.
    Schlagwort(e): SPACE RADIATION
    Materialart: Solar Physics; 38; Sept
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  • 185
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    Observation of a cosmic gamma-ray burst on Apollo 16. II - X-ray time profile and source location (1974)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: A burst of X-rays was detected during the trans-earth coast phase of Apollo 16 on Apr. 27, 1972 at 10:68 UT, simultaneously with the observation of a transient event by a gamma-ray spectrometer aboard the same spacecraft. The two instruments provide a broad energy range of more than three orders of magnitude for describing the spectral distribution of this event. The conclusion that the incident flux was X-rays and not charged particles is based on the fact that the particle flux detectors in the Apollo gamma ray spectrometer and on the Vela 6A, which also observed the event, did not respond. The time variation of the total count rate in the X-ray range before and after corrections for detector geometry and the analysis for source direction is presented.
    Schlagwort(e): SPACE RADIATION
    Materialart: Astrophysical Journal; 194; Nov. 15
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  • 186
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    Observation of a cosmic gamma-ray burst on Apollo 16. I - Temporal variability and energy spectrum (1974)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: A cosmic gamma-ray event occurring April 27, 1972 at 10.68 UT was observed by gamma-ray and X-ray spectrometers on Apollo 16 as well as by Vela 6A. Analysis has yielded a detailed time profile of the entire event, an energy spectrum covering three order of magnitude (2.0 to 7.9 KeV and 0.067 to 5.1 MeV) and a source location. A well-defined onset prior to the main impulse period and a probable precursor are reported. The total energy of the event over the observed range was 2 x 10 to the minus 4th power ergs/sq cm. The data indicate the presence of a hard component which persists during the entire event, with a softer variable component becoming dominant during the most explosive burst portion.
    Schlagwort(e): SPACE RADIATION
    Materialart: Astrophysical Journal; 194; Nov. 15
    Format: text
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  • 187
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    Composition of heavy cosmic rays from 25 to 180 MeV per atomic mass unit (1974)
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    Publikationsdatum: 2019-06-27
    Beschreibung: Relative abundances of elements from neon through zinc in the energy range from 25 to 180 MeV per amu have been determined from particle tracks in polycarbonate detectors exposed on the Apollo 16 mission. The ratios of elemental abundances of Ne + Si and 17 less than Z less than 25 to Fe + Co + Ni are found to be 5.8 plus or minus 1.9 and 2.1 plus or minus 0.7, respectively, in agreement with the results from cellulose triacetate detectors by O'Sullivan et al. (1973). These results imply that the heavy particles observed are predominantly galactic in origin. The availability to investigators of unetched plastic detectors exposed to solar-flare particles on the Apollo 16 mission is noted.
    Schlagwort(e): SPACE RADIATION
    Materialart: Astrophysical Journal; 193; Nov. 1
    Format: text
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  • 188
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    Static aeroelasticity and the flying wing, revisited (1974)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: The roll dynamic behavior of some wing configurations is examined. Analysis shows that the static divergence instability which occurs for symmetrical or clamped sweptforward wings is modified by roll freedom. The instability found in the present highly idealized analysis is still of an aperiodic nature, but at a speed above the conventional divergence speed. The magnitude of this difference is seen to be a function of the ratio of the wing roll mass moment of inertia to the mass moment of inertia of the wing about the roll axis, and this difference may be quite significant.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: Journal of Aircraft; 11; Nov. 197
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  • 189
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    Cosmic-ray exposure history at the Apollo 16 and other lunar sites - Lunar surface dynamics (1974)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: Concordant Kr-81/Kr exposure ages for four station 11 breccias indicate an age of 50.3 plus or minus 0.8 m.y. for North Ray Crater. Ray structures visible from orbital photography suggest that stations 8 and 9 should contain a substantial amount of South Ray ejecta. Concordant Kr-81/Kr exposure ages at these sites indicate an age for South Ray Crater of 2.04 plus or minus 0.08 m.y. Surface effects show good general agreement with this young age, but discrepancies on a sample-by-sample basis seem to indicate that extensive presurface irradiations must have occurred.
    Schlagwort(e): SPACE RADIATION
    Materialart: Geochimica et Cosmochimica Acta; 38; Oct. 197
    Format: text
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  • 190
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    The radiation belts of Jupiter (1974)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: The cloud of relativistic electrons which forms the Jupiter radiation belts at a distance of a few Jovian radii from the planet is considered. The inner belt is shown to consist of electrons with about three times the energy of those in the outer zone, and to have an equatorial density which is about one half the peak density in the outer zone. The pitch angle distribution of the electrons in the outer zone becomes gradually more confined to the magnetic equator with increasing distance from the planet.
    Schlagwort(e): SPACE RADIATION
    Materialart: Icarus; 23; Sept
    Format: text
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  • 191
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    Eigenproblem solution of damped structural systems (1974)
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    Publikationsdatum: 2019-06-27
    Beschreibung: This article presents an efficient numerical algorithm and a complete listing of the associated computer program, developed for the eigenproblem solution of discrete damped structures, including spinning ones. The numerically stable procedure is based on a combined Sturm sequence and inverse iteration technique, which fully exploits the banded form of the relevant matrices and proves to be most substantially economical when compared to similar existing softwares. Numerical results are presented for representative structures, solved by the present computer program written in FORTRAN V for the JPL UNIVAC 1108 computer.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: International Journal for Numerical Methods in Engineering; 8; 4, 19; 1974
    Format: text
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  • 192
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    Effects of interplanetary shock waves on energetic charged particles (1974)
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    Publikationsdatum: 2019-06-27
    Beschreibung: Experimental data on the influence of interplanetary perpendicular and oblique shock waves on the ambient energetic protons are presented along with a theoretical analysis of the acceleration of particles in almost perpendicular shock waves. It was found that low-energy protons can be accelerated in perpendicular shock waves by repeated crossings of the shock front up to a maximum energy given by the product of their initial energy times the ratio of the magnetic fields. High-energy protons need to stay at the shock front for longer times than low-energy protons in order to reach the same relative energy gain. In the theoretical study of proton acceleration at almost perpendicular shock waves, it was found that protons reflected at shock waves with the angle between the upstream magnetic field and the shock normal greater than about 80 deg achieve large energy gains at the shock front. The larger this angle, the higher the energy gain. However, the reflection and energization of protons at these shock waves is not 'instantaneous', neither is it a one-step process: it is performed through repeated crossings of the shock front.
    Schlagwort(e): SPACE RADIATION
    Materialart: Journal of Geophysical Research; 79; Oct. 1
    Format: text
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  • 193
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    Modulation of cosmic ray protons and helium nuclei near solar maximum (1974)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: Balloon observations of proton and helium spectra in 1970, 1971, and 1972, which extend previous work for the period 1965-1969, reveal a factor of about 1.85 deviation from a single-valued regression at low rigidities. This deviation decreases with increasing rigidity for both species. The period 1969-197 is unique, because time variations at low and high energies were anticorrelated. When satellite observations are used to extend the balloon observations to energies below 100 MeV/nucleon, the proton spectrum shows a steeper slope in 1970 and 1972 than the characteristic J = AT spectrum observed during 1965-1969. The slope of the helium spectrum became continuously flatter during the same period (1970-1972). Computer-generated spectra based on simple two-parameter modulation models describe the basic features of the observations, if one of the variable parameters is used to characterize the rigidity dependence of the diffusion coefficient. On the other hand, models that do not allow such a variation are not consistent with the observations.
    Schlagwort(e): SPACE RADIATION
    Materialart: Journal of Geophysical Research; 79; Oct. 1
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  • 194
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    The diffusive idealization of charged-particle transport in random magnetic fields (1974)
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    Publikationsdatum: 2019-06-27
    Beschreibung: The uniqueness and accuracy of the equations which describe the transport of charged particles diffusing in a random magnetic field parallel to a relatively large guiding field is examined. With regard to uniqueness, it is found that the same coefficient of diffusion is obtained by three methods that have apparently led to discrepancies in previous work. With regard to accuracy, it is found that two corrections must be added to Fick's law in which the diffusive flux is proportional to the gradient of the density. Explicit expressions are given for a characteristic time and a characteristic length which describe the corrections.
    Schlagwort(e): SPACE RADIATION
    Materialart: Astrophysical Journal; 193; Oct. 1
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  • 195
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    Interaction of metagalactic X-UV radiation with galactic hydrogen (1974)
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    Publikationsdatum: 2019-06-27
    Beschreibung: Calculations show that the existence of a metagalactic X-UV flux of the intensity required to explain the high-latitude soft X-ray observations, plus a reasonable extrapolation toward lower energies, is consistent with the existence of neutral hydrogen in galaxies. Shielding by H II slabs can be effective both in the solar neighborhood and in the peripheries of galaxies out to a radius of 30 to 40 kpc. At earlier cosmological epochs shielding is less efficient. The soft X-ray spectrum as observed by Yentis et al. (1972) is difficult to reconcile with a purely extragalactic origin for the flux. A local source of ionization also may be necessary to explain the pulsar dispersion data.
    Schlagwort(e): SPACE RADIATION
    Materialart: Astronomy and Astrophysics; 34; 3, Se; Sept
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  • 196
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    Analysis of twisting stiffness for a multifiber composite layer (1974)
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    Publikationsdatum: 2019-06-27
    Beschreibung: The twisting stiffness of a rectangular cross section consisting of a single row of solid circular cross-section fibers embedded in a matrix is analyzed. The problem is formulated as a Dirichlet torsion problem of a multielement region and solved by the boundary-point least-squares method. Numerical results for a single-fiber square cross section compare favorably with previous relaxation-method results. New numerical results for three and five-fiber composites suggest that the torsional rigidity of a multifiber composite can be approximated from the torsional rigidities of single and three-fiber models.
    Schlagwort(e): STRUCTURAL MECHANICS
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  • 197
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    Interstellar scattering of pulsar radiation. 1: Scintillation (1974)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: An investigation of the intensity fluctuations of 28 pulsars near 0.4 GHz indicates that scintillation spectra have a Gaussian shape, scintillation indices are near unity, and the scintillation bandwidth depends linearly on dispersion measure. Observations near 2.5 GHz suggest a strong dependence of the frequency at which scintillation indices fall below unity on dispersion measure. Multistation measurements of scintillation provide values or limits for the scale size of the scattering diffraction pattern. The dependences of scattering parameters on dispersion measure is discussed in terms of the current models. It is suggested that any line of sight through the galaxy encounters increasingly rare, increasingly large deviations of thermal electron density on the scale of 10 to the 11th power cm.
    Schlagwort(e): SPACE RADIATION
    Materialart: NASA-TM-X-70789 , X-693-74-316
    Format: application/pdf
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  • 198
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    Sizing of complex structure by the integration of several different optimal design algorithms (1974)
    In:  CASI
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    Publikationsdatum: 2019-06-27
    Beschreibung: Practical design of large-scale structures can be accomplished with the aid of the digital computer by bringing together in one computer program algorithms of nonlinear mathematical programing and optimality criteria with weight-strength and other so-called engineering methods. Applications of this approach to aviation structures are discussed with a detailed description of how the total problem of structural sizing can be broken down into subproblems for best utilization of each algorithm and for efficient organization of the program into iterative loops. Typical results are examined for a number of examples.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: L-9738 , AGARD Structural Optimization; 19 p
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  • 199
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    On the effect of orthotropy in a cracked cylindrical shell (1974)
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    Publikationsdatum: 2019-06-27
    Beschreibung: A pressurized cylindrical shell containing a longitudinal crack is considered. It is assumed that the material has a special orthotropy - namely, that the shear modulus of the sheet may be evaluated from the measured Young's moduli and the Poisson's ratios and is not an independent material constant. Two examples, one for a mildly orthotropic (titanium) and the other for a strongly orthotropic (graphite) material approximately satisfying the condition of special orthotropy are given. The results show that the stress intensity factors are rather strongly dependent on the degree of orthotropy.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: International Journal of Fracture; 10; Sept
    Format: text
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  • 200
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    Dynamic analysis of an elastic plate on a thin, elastic foundation (1974)
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    Publikationsdatum: 2019-06-27
    Beschreibung: A review, correction, and extension of Vlasov and Leont'ev's (1966) analysis of beams, plates, and shells on elastic foundations is presented, and an improved theory for the motion of an elastic foundation is developed. The interaction of two or more plates resting on a common foundation is included. A simplified model is derived which appears useful for some applications.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: Journal of Sound and Vibration; 35; Aug. 8
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