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  • General Chemistry  (4.740)
  • Analytical Chemistry and Spectroscopy  (2.128)
  • ASTROPHYSICS
  • AERODYNAMICS
  • Cell & Developmental Biology
  • 1970-1974  (9.250)
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  • 1
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    Short-range repulsive forces between atoms and molecules of atmospheric gases (1974)
    In:  CASI
    Details
    Publikationsdatum: 2006-01-11
    Beschreibung: Experimental determination of the paired interaction potential of atoms and molecules composing the atmospheres of the earth and the planets is described.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Interplanet. Medium and Phys. of the Magnetosphere (NASA-TT-F-784); p 275-281
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  • 2
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    An investigation of the cosmic radiation in the vicinity of the moon on the Luna 10, 11, and 12 artificial lunar satellites (1974)
    In:  CASI
    Details
    Publikationsdatum: 2006-01-11
    Beschreibung: Research on the primary cosmic radiation and solar cosmic rays from the Luna 10, 11, and 12 artificial lunar satellites is reviewed. Data on the vertical distribution of cosmic rays above the moon's surface are presented, and the albedo for the primary radiation is determined. The fluxes of electrons with energies from 30 to 300 keV were registered in the solar cosmic rays. Rapid variations of the electron flux were observed. The angular distributions of 0.5-10 MeV protons moving together with the corpuscular streams responsible for Forbush decreases were investigated.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Interplanet. Medium and Phys. of the Magnetosphere (NASA-TT-F-784); p 151-173
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  • 3
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    Structural formations in the interplanetary medium (1974)
    In:  CASI
    Details
    Publikationsdatum: 2006-01-11
    Beschreibung: Research on the fine structure of the interplanetary medium is reviewed. The characteristics of shock waves, filaments, and contact surfaces according to space probe measurements are discussed.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Interplanet. Medium and Phys. of the Magnetosphere (NASA-TT-F-784); p 103-123
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  • 4
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    High-frequency turbulence in the cosmic plasma (1974)
    In:  CASI
    Details
    Publikationsdatum: 2006-01-11
    Beschreibung: The problem of quasistationary high frequency Langmuir turbulence, which is one of the types of turbulence encountered in the cosmic plasma, is examined theoretically.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Interplanet. Medium and Phys. of the Magnetosphere (NASA-TT-F-784); p 83-102
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  • 5
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    Dissipation of energy in model experiments (1974)
    In:  CASI
    Details
    Publikationsdatum: 2006-01-11
    Beschreibung: Interaction studies of a plasma stream with a magnetic dipole have shown that the thickness of the plasma/field interlayer is considerably greater than the characteristic plasma dimension c/omega sub 0. Broadening of the layer is due to the formation of a collisionless shock wave. To demonstrate collisionless dissipation, the Joulean losses were calculated using the conductivity value obtained from the skin layer thickness. Analysis of the various physical processes showed that the hypothesis of collisionless dissipation of the directional plasma flow is justified.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Interplanet. Medium and Phys. of the Magnetosphere (NASA-TT-F-784); p 59-67
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  • 6
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    Certain problems in the physics of the magnetosphere (1974)
    In:  CASI
    Details
    Publikationsdatum: 2006-01-11
    Beschreibung: A review of experimental and theoretical studies devoted to analysis of physical processes in the magnetosphere is presented. Attention is focused on the interrelationships among the most important geophysical phenomena in the magnetosphere: magnetic storms, auroras, the radiation belts, and processes in the geomagnetic tail. Recommendations are submitted for future experiments that are needed for development of a theory of magnetospheric phenomena.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Interplanet. Medium and Phys. of the Magnetosphere (NASA-TT-F-784); p 1-33
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  • 7
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    Neutron stars with main sequence binary companions as low luminosity X-ray sources (1974)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-16
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astronomy and Astrophysics; 37; 1, De; Dec. 197
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  • 8
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    The interaction of interstellar gas with stellar density wave packets (1974)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: We have numerically studied the interaction between interstellar gas and a gravitational perturbation produced by a fluctuation in the stellar mass distribution. For a simple equation of state, shock waves develop even if the gravitational perturbation is aperiodic and transient. In a medium which can change thermal phase, shocks do not form and the gas makes a transition directly to the cold, dense phase. The cold material has an anomalous velocity imparted to it by the gravitational perturbation and it becomes an accretion front moving through the hot gas and capturing it. The accretion fronts trigger thermal phase change on a large scale and can reproduce the extent of observed cold clouds. Furthermore their high mass is favorable to gravitational instability and subsequent star formation.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astronomy and Astrophysics; 36; 2, No; Nov. 197
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  • 9
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    The Apsidal-motion test for models of main-sequence stars (1974)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: Apsidal-motion constants, k2, have been determined for models of homogeneous main-sequence stars constructed with the new 'Thomas-Fermi' opacities of Carson. These models are similar to those constructed with the 'hydrogenic' opacities of Cox and Stewart up to about 7 solar masses, but yield smaller values of k2 at higher masses. Nevertheless, the new theoretical constants are still systematically too large compared with most of the empirical constants known for members of well-observed binary systems. Uniform rotation is found to lower the theoretical constants only slightly. The effect of normal evolution during core hydrogen burning, however, produces good detailed agreement with observations. The primary of alpha Vir is probably evolving normally if Carson's opacities are adopted.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal; 194; Dec. 15
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  • 10
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    Main sequence models for massive zero-metal stars (1974)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: Zero-age main-sequence models for stars of 20, 10, 5, and 2 solar masses with no heavy elements are constructed for three different possible primordial helium abundances: Y=0.00, Y=0.23, and Y=0.30. The latter two values of Y bracket the range of primordial helium abundances cited by Wagoner. With the exceptions of the two 20 solar mass models that contain helium, these models are found to be self-consistent in the sense that the formation of carbon through the triple-alpha process during premain sequence contraction is not sufficient to bring the CN cycle into competition with the proton-proton chain on the ZAMS. The zero-metal models of the present study have higher surface and central temperatures, higher central densities, smaller radii, and smaller convective cores than do the population I models with the same masses.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysics and Space Science; 31; Nov. 197
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  • 11
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    Interplanetary sector structure - 1970-1972 (1974)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: Determinations of interplanetary sector structure for the years 1970-1972 reveal the persistence of sector patterns during the decreasing portion of the solar cycle. The simple two-sector pattern of 1969 persists through 1970 but develops greater complexity in 1971-1972.-
    Schlagwort(e): ASTROPHYSICS
    Materialart: Journal of Geophysical Research; 79; Dec. 1
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  • 12
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    Lifting-surface theory for a semi-infinite wing in oblique gust (1974)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: An unsteady lifting-surface theory is developed for the calculation of the airload on a semi-infinite-span thin wing in a compressible flow due to interaction with an oblique gust. By using the solutions obtained for a two-dimensional wing, the problem is formulated so that the unknown is taken to be the difference between the airload on the semi-infinite wing and that on a two-dimensional wing under the same gust conditions. Since this airload difference is nonzero only near the wing tip, the control points need be distributed in the tip region only; this significantly simplifies the numerical procedure. Results are presented for a wing with rectangular tip. The implication for noise and unsteady loads due to blade-vortex interaction for helicopter rotors is discussed.
    Schlagwort(e): AERODYNAMICS
    Materialart: AIAA Journal; 12; Dec. 197
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  • 13
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    Distinctive patterns on the surface of slowly rotating stars whose oscillations are nonlinearly coupled (1974)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: Slowly rotating stars which are oscillating at small amplitude in a broad spectrum of g-modes should display strong surface nonuniformities if even weak nonlinear coupling exists between the modes. Oscillatory power will be concentrated into distinctive patterns which rotate rigidly in spite of differential rotation in the outer stellar layers. Each pattern rotates at a constant rate slower than the star as a whole according to a very simple law of rotation. Virtually all the rotation rates are within 9 per cent of the stellar rate. Evidence is cited that the sun may be oscillating, so other stars along the main sequence may be oscillating, also. If zones obeying the predicted rotation law can be detected in a star, then the rotation rate of the stellar interior becomes known, and differential rotation is negligible over most of the stellar mass.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal; 193; Nov. 1
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  • 14
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    Planetary entry aerothermodynamics. II - Computational analyses and flight experience (1974)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: Limitations concerning the possibility to simulate all the significant flow and thermal phenomena occurring during the entry of a space vehicle into a planetary atmosphere make it necessary to rely on computational analyses to obtain the required data for the design of the spacecraft needed for the NASA missions planned for the next two decades. 'Benchmark' computer programs concerned with complete, detailed, and accurate computational solutions of entry problems are considered along with programs representing engineering approximations for cases in which the accuracy provided by the benchmark programs is not needed. The information obtainable by computational analysis has to be supplemented by actual flight experience in order to meet the goals of the NASA entry-technology program. The individual space missions planned for the coming years are examined together with the possibilities for obtaining the data needed to satisfy the entry requirements in each case.
    Schlagwort(e): AERODYNAMICS
    Materialart: Astronautics and Aeronautics; 12; Dec. 197
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  • 15
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    The ethynyl radical C2H - A new interstellar molecule (1974)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: Four new interstellar lines have been detected near 87.3 GHz. Based on laboratory ESR data these lines have been positively defined as hyperfine components of the lowest rotational transition of the ethynyl radical C2H. The observations gave precise values for the C2H rotation, spin-doubling, and hyperfine constants. C2H is probably one of the most abundant interstellar polyatomic molecules yet detected.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal; 193; Nov. 1
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  • 16
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    Influence of opacity on the pulsational stability of massive stars with uniform chemical composition. II - Modified Kramers opacity (1974)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: The pulsational stability of massive, chemically homogeneous stars of Population I has been investigated for a range of simple opacity representations consisting of a straight sum of electron-scattering and modified Kramers opacity. The critical mass for stability against nuclear-energized pulsations is found to be extraordinarily sensitive to small changes in the coefficient and/or temperature exponent of the absorption part of the opacity law. A gradual increase in the atomic absorption (dominant near the stellar surface) first raises the critical mass, then restricts the upper mass limit for instability, and finally eliminates pulsational instability at all masses.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal; 193; Nov. 1
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  • 17
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    Equation of state at ultrahigh densities. I (1974)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: Particular attention is given to the physics involved in the derivation of an equation of state for a density range from 10 g/ccm to 200,000 billion g/ccm and for the density region from 200,000 billion g/ccm to 2,000,000 billion g/ccm. Conditions in a high density regime with densities exceeding 500,000 billion g/ccm are examined. Equations of state for a gas of pure neutrons and for a gas of nucleons, electrons, and hyperons are considered.
    Schlagwort(e): ASTROPHYSICS
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  • 18
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    Cometary coma ions (1974)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: For comets whose nuclei are composed of water ice conglomerates it is shown that the ion H3O(+) can predominate to distances of 5000 km in the subsolar direction. Beyond this distance H2O(+) is the most important ion. The crossover point is a sensitive function of the rate of evaporation from the nucleus. The presence of ammonia or metals such as sodium, in concentrations greater than 0.1% H2O, can lead to NH4(+) and Na(+) ions.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal; 193; Oct. 1
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  • 19
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    An empirical line-blanketing study of Am stars (1974)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: Metallic line-blanketing coefficients have been measured over the wavelength range from 3800 to 4700 A in a sample of 20 Am and normal A stars. An expression for the logarithmic iron abundance has been calibrated in terms of effective temperature and a mean line-blocking coefficient. This makes it possible to determine the atmospheric iron abundance in sharp-lined Am and A stars with an accuracy of better than plus or minus 0.1 dex, using only line-blocking measurements and a photometric effective temperature.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal; 193; Oct. 1
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  • 20
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    Li production in alpha-alpha reactions (1974)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: The cross section for Li-7 production in alpha-alpha reactions is shown to be increased by about a factor of 2 due to the excitation levels of Li-7 and Be-7 at 478 keV and 431 keV, respectively. The cross section for Li-6 production, however, remains the same as calculated on the basis of the detailed balance principle. The lines at 478 keV and 431 keV may link Li-7 production to feasible gamma-ray observations.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astronomy and Astrophysics; 34; 3, Se; Sept
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  • 21
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    Analysis of acoustic radiation in a jet flow environment (1974)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: The analysis of sound fields from arbitrary source distributions in terms of Legendre and spherical Hankel functions is well known. The purpose of this paper is to extend this classical method of analysis to environments such as jet flows where flow and flow gradients are inherently present. The wave-equation governing the radiation of sound in such an environment is derived. The steady state flow and flow gradients in the axial and transverse directions appear as coefficients in the terms of the wave-equation. A semi-numerical method is used to solve the wave-equation in terms of modified spherical harmonics yielding the phase velocities and the directivities of an infinite set of modes. The directivity of each mode is obtained in terms of modified Legendre functions by numerical integration. Some results of these directivity and phase-velocity calculations are presented for a limited number of frequency and flow parameters. Both convective and shear refraction are shown to be important.
    Schlagwort(e): AERODYNAMICS
    Materialart: Journal of Sound and Vibration; 36; Sept. 8
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  • 22
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    Unified approach to aerodynamic sound generation in the presence of solid boundaries (1974)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: A general equation governing aerodynamic sound generation in the presence of solid boundaries is derived. It is shown that all the theories in the literature appear as special cases of this general equation. Derived special equations for propeller and fan noise are likewise shown to be more general than the conventional equations in that they make allowance for variation in retarded time over the blade surfaces.
    Schlagwort(e): AERODYNAMICS
    Materialart: Acoustical Society of America; vol. 56
    Format: text
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  • 23
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    Automatic numerical generation of body-fitted curvilinear coordinate system for field containing any number of arbitrary two-dimensional bodies (1974)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: A method for automatic numerical generation of a general curvilinear coordinate system with coordinate lines coincident with all boundaries of a general multi-connected region containing any number of arbitrarily shaped bodies is presented. With this procedure the numerical solution of a partial differential system may be done on a fixed rectangular field with a square mesh with no interpolation required regardless of the shape of the physical boundaries, regardless of the spacing of the curvilinear coordinate lines in the physical field, and regardless of the movement of the coordinate system. Numerical solutions for the lifting and nonlifting potential flow about Joukowski and Karman-Trefftz airfoils using this coordinate system generation show excellent comparison with the analytic solutions. The application to fields with multiple bodies is illustrated by a potential flow solution for multiple airfoils.
    Schlagwort(e): AERODYNAMICS
    Materialart: Journal of Computational Physics; 15; July 197
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  • 24
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    Analysis of propagation of waves of acoustic frequencies in curved ducts (1974)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: The propagation of waves of acoustic frequencies in curved ducts of rectangular cross section is studied for the first four modes. The analysis makes use of Bessel functions of the order (n + 1/2) to construct curves of wavenumber in the duct versus imposed wavenumber and to determine the profile of vibrational velocities. A wide range of duct widths and unrestricted radii of curvature have been considered. The characteristics of motion in a bend are compared with propagation of waves in a straight duct, and important differences in the behavior of waves are noted.
    Schlagwort(e): AERODYNAMICS
    Materialart: Acoustical Society of America; vol. 56
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  • 25
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    Axial flow measurements in trailing vortices (1974)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: A scanning laser Doppler velocimeter was used to measure the axial velocity defect in the cores of trailing vortices behind a lifting airfoil of rectangular planform. Data were obtained at several different angles of attack and downstream distances ranging from 30 to 1000 chord lengths. The test was designed to obtain continuous data from the near field into the far field while removing uncertainties associated with the interpretation of data obtained by the hydrogen bubble technique. The measured velocities of V sub x/U sub infinity are compared with those predicted. The agreement is remarkably good over the entire range of downstream distances, which supports the credibility of calculating axial velocities using the results of Moore and Saffman (1973).
    Schlagwort(e): AERODYNAMICS
    Materialart: AIAA Journal; 12; Aug. 197
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  • 26
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    Vortex measurements behind a swept wing transport model (1974)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: A backscatter laser Doppler velocimeter which simultaneously senses the axial and the tangential components of the velocity has been used to measure the velocity distributions in the near wake of a swept wing semispan transport model in a wind tunnel. The model configuration included nacelles, pylons, antishock bodies, and wing flaps which could be deflected 27 deg. Typical wake vortex velocity profiles are presented for the flaps-retracted and the flaps-deployed 27 deg configurations, respectively.
    Schlagwort(e): AERODYNAMICS
    Materialart: Journal of Aircraft; 11; June 197
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  • 27
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    Shock shapes of blunt bodies in hypersonic helium, air, and CO2 flows (1974)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: A primary factor governing hypersonic flowfield characteristics of blunt vehicles entering planetary atmospheres is the normal shock density ratio. Hence, a means of duplicating or simulating the high density ratios experienced during planetary entry is needed. One facility having the capability of generating a range of hypersonic-hypervelocity flow conditions in arbitrary test gases is the expansion tube. Preliminary shock shape results obtained in the Langley 6-in. expansion tube at hypersonic conditions are presented. Normal shock density ratios from approximately 4 to 19 were generated using helium, air, and CO2 test gases at freestream velocities from 5 to 7 km/sec. Test models were a flat-faced cylinder and the Viking aeroshell.
    Schlagwort(e): AERODYNAMICS
    Materialart: AIAA Journal; 12; Mar. 197
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  • 28
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    Computation of transonic flow about lifting wing-cylinder combinations (1974)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: Some results are described for a lifting rectangular wing centrally located on a circular-cylindrical body. This simple configuration has been utilized in order to assess the merits of a mapping technique for wing-body configurations. The procedure employed makes use of a coordinate transformation to simplify specification of the surface boundary condition in the computation of the flow about the wing. The method can be extended to incorporate wing sweep, finite length body of noncircular cross section, and arbitrary wing placement; however, these extensions involve a considerable increase in complexity of the problem.
    Schlagwort(e): AERODYNAMICS
    Materialart: Journal of Aircraft; 11; Apr. 197
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  • 29
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    A vortex entrainment model applied to slender delta wings (1974)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: A mathematical model of the vortex flow over a slender sharp-edged delta wing is proposed, and is shown to provide good agreement with the experiment. Although the technique requires experimental data in the form of the vortex core locations, it does account for the previously ignored mass entrainment of the vortex core.
    Schlagwort(e): AERODYNAMICS
    Materialart: AIAA Journal; 12; Jan. 197
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  • 30
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    Extraction of derivatives from flight data for several aircraft, using the LRC interactive computer system (1974)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: Results are presented of a procedure for estimating stability and control parameters from flight data, by using maximum likelihood methods employing an interactive computer system, which was established at the NASA Langley Research Center. Problems encountered are discussed.
    Schlagwort(e): AERODYNAMICS
    Materialart: Parameter Estimation Tech. and Appl. in Aircraft Flight Testing; p 49-76
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  • 31
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    Identification of aircraft stability and control derivatives in the presence of turbulence (1974)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: A maximum likelihood estimator for a linear system with state and observation noise is developed to determine stability and control derivatives from flight data obtained in the presence of turbulence. The formulation for the longitudinal short-period mode is presented briefly, including a special case that greatly simplifies the problem if the measurement noise on one signal is negligible. The effectiveness and accuracy of the technique are assessed by applying it first to simulated flight data, in which the true parameter values and state noise are known, then to actual flight data obtained in turbulence. The results are compared with data obtained in smooth air and with wind-tunnel data. The complete maximum likelihood estimator, which accounts for both state and observation noise, is shown to give the most accurate estimate of the stability and control derivatives from flight data obtained in turbulence. It is superior to the techniques that ignores state noise and to the simplified method that neglects the measurement noise on the angle-of-attack signal.
    Schlagwort(e): AERODYNAMICS
    Materialart: Parameter Estimation Tech. and Appl. in Aircraft Flight Testing; p 77-114
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    A comparison of two methods of extracting stability derivatives from flight test data (1974)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: Two methods for extracting stability derivatives from flight data are compared. A modified Newton-Raphson quasilinearization minimization technique and a digital-analog (hybrid) matching technique were used to analyze the same data maneuvers obtained from two aircraft. About 70 maneuvers from an F-111E aircraft were analyzed over a Mach number range of 0.3 to 2.0 and an angle of attack range of 3 to 19 degrees. About 20 maneuvers were analyzed for the X-24A lifting body at Mach numbers of 0.5, 0.8, and 0.9, and an angle of attack range of 4 to 13 degrees. Stability derivatives were extracted from these maneuvers and the results from the two techniques, along with wind tunnel results, were compared.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA. Flight Res. Center Parameter Estimation Tech. and Appl. in Aircraft Flight Testing; p 43-48
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  • 33
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    The stability of supermassive stars in the Parametrized Post-Newtonian framework (1974)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: The binding energy and stability of supermassive stars (SMS's) are examined in the framework of the Parametrized Post-Newtonian (PPN) formalism of Will and Nordvedt. The PPN formalism encompasses the post-Newtonian limit of virtually every theory of gravity, differentiating between theories by means of nine PPN parameters. A general expression is derived for the energy integral in the PPN framework, and those theories in which the energy will be conserved are defined. In all such theories, a SMS of radius less than a critical radius will be unstable against adiabatic radial perturbations. Present experimental limits on the PPN parameters gamma and beta do not exclude the possibility of the existence of stable, non-rotating, hydrogen-burning SMS's of masses an order of magnitude larger than the upper limit for the mass of such stars predicted in general relativity.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysics and Space Science; 31; Dec. 197
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  • 34
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    A comparison of homogeneous stellar models based on the Cox-Stewart and Carson opacities (1974)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal; 194; Dec. 15
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  • 35
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    Fine-scale structure of a cold hydrogen layer (1974)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: Neutral-hydrogen absorption-line interferometer observations are reported for five continuum radio sources situated behind an extensive layer of cold interstellar H I gas. In contrast to low-spatial-resolution emission-line observations reported earlier which show the large-scale uniformity of the layer, the high-spatial-resolution absorption-line observations reveal variations in the velocity and density within the layer. The new results together with the old indicate the apparent coexistence of a large-scale mechanism for triggering the formation of cold hydrogen and an instability mechanism leading to small-scale irregularities.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal; 194; Dec. 1
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  • 36
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    Degeneracy effects of neutrino mass ejection in supernovae (1974)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: A neutrino mechanism is discussed in order to explain supernovae in massive stars. An argument is presented for supernova mass ejection through leptonic neutrino transport characteristics suppressed by the arbitrary zero chemical potential condition. Results show that lepton conservation effects may be important in supernova neutrino transport. At low temperature and density the diffusion approximation becomes less precise because of the long mean free paths of low energy neutrinos. The amount of equilibrium neutrino spectrum affected here is small over most of the collapsing supernova structure.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Nature; 252; Nov. 22
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  • 37
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    Correlation for estimating vortex rotational velocity downstream dependence (1974)
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    Publikationsdatum: 2011-08-16
    Beschreibung: Description of a correlation, derived from water tank measurements in the wake of wings towed under water, that makes it possible to predict the downstream distance behind an aircraft in flight where its trailing vortex will begin to decay. Comparisons of measured and predicted data are discussed.
    Schlagwort(e): AERODYNAMICS
    Materialart: Journal of Aircraft; 11; Nov. 197
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  • 38
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    Roll-up of aircraft trailing vortices using artificial viscosity (1974)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: The artificial viscosity method of Kuwahara and Takami (1973) is used to calculate the roll-up of trailing vortices behind a number of practical aerodynamic configurations. Where possible, the results are compared for core location with available experimental data.
    Schlagwort(e): AERODYNAMICS
    Materialart: Journal of Aircraft; 11; Nov. 197
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  • 39
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    Weak interstellar lines in the visible spectrum of zeta Ophiuchi (1974)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal; 193; Oct. 1
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  • 40
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    On the theory of thermal runaway in the hydrogen envelope of a white dwarf (1974)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: An evolutionary sequence was calculated for a white dwarf on which a hydrogen rich envelope is assumed to increase with time. The stellar models were computed by integrating numerically the system of stellar structure equations by means of the Henyey method. The accretion of matter was assumed to be quasi-static. Near the point of the chemical discontinuity, a temperature maximum is shown to arise, and hydrogen ignites; a thin shell energy source is formed which is thermally unstable. The resulting thermal runaway was investigated numerically and by means of a simple approximation based on the energy balance in the hydrogen burning shell source.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrometrics and Astrophysics, No. 17 (NASA-TT-F-15768); p 1-55
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  • 41
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    Estimates of the Venus atmosphere optical characteristics with application to the problem of photographing its clouds and surface (1974)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: Optical parameters investigated and solved for included: (1) cloud layer albedo and cloud cover optical thickness; (2) planetary surface self-radiation influence; (3) light flux distribution as function of atmospheric height; (4) upper estimate of the observed contrasts; (5) surface optical parameters; and (6) contrast decrease with altitude.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Space Iconics (NASA-TT-F-798); p 121-135
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  • 42
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    Applicability of the diffusion approximation (1974)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: Several methods using an approximate form of the scattering indicatrix are discussed for simplifying the calculation of radiation transport in planetary atmospheres.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Space Iconics (NASA-TT-F-798); p 75-84
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  • 43
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    Influence of ablation impurities on blunt body re-entry ionization (1974)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: Electron density profiles which include the effect of an ablated sodium impurity were computed for the boundary layer on a blunt-nosed body re-entering the atmosphere at 7.62 km/sec. Profiles are computed from the nose to a distance of four diameters along the RAM C-payload. A finite-difference, laminar, nonequilibrium chemistry boundary-layer program was used. Comparison of theory with S-band diagnostic antenna results, electron concentration deduced from X- and C-band attenuation data, and Langmuir probe data at several different aft body locations show that agreement is good at high altitude. At the lower altitudes there is disagreement between theory and S-band antenna data where the apparent discrepancy is attributed to the three-body recombination rate constant used for deionization of sodium coupled with the effect of angle of attack.
    Schlagwort(e): AERODYNAMICS
    Materialart: AIAA Journal; 12; June 197
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  • 44
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    Some after-dinner reflections on system identification (1974)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: The growth of the field of system identification is discussed along with changes in methodology which have taken place in recent years. The similarity between pattern recognition and system identification is pointed out, involving the modelling in the latter and the feature selection problem in the former. It is stated that once a model is formulated, including the disturbances and measurement errors, the parameter finding can be formulated as a statistical estimation problem. The various techniques and their application are discussed.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA. Flight Res. Center Parameter Estimation Tech. and Appl. in Aircraft Flight Testing; p 381-385
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  • 45
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    Systems identification - reprise and projections (1974)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: A state-of-the-arts review is given for the field of system identification. Progress in the field is traced from the early models of dynamic systems by Sir Isaac Newton up to the present day use of advanced techniques for numerous applications.
    Schlagwort(e): AERODYNAMICS
    Materialart: Parameter Estimation Tech. and Appl. in Aircraft Flight Testing; p 375-379
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  • 46
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    A new criterion for modeling systems (1974)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: The criterion that is proposed is an expected value of the mean square response error as an alternative to testing a model against new data. Modeling with respect to this new criterion does not change the estimate for a given model format from a maximum likelihood estimate or mean square response error estimate. The new criterion does, however, provide a means of comparing models with different formats and varying complexity. A numerical example is used to illustrate the application of the proposed criteria and the problem of searching for the best model. For all but the most trivial system identification problems, it is shown that a prohibitive number of combinations of terms of the model must be investigated to ensure the final model is best.
    Schlagwort(e): AERODYNAMICS
    Materialart: Parameter Estimation Tech. and Appl. in Aircraft Flight Testing; p 291-313
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  • 47
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    Effects of flight instrumentation errors on the estimation of aircraft stability and control derivatives (1974)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: An error analysis program based on an output error estimation method was used to evaluate the effects of sensor and instrumentation errors on the estimation of aircraft stability and control derivatives. A Monte Carlo analysis was performed using simulated flight data for a high performance military aircraft, a large commercial transport, and a small general aviation aircraft for typical cruise flight conditions. The effects of varying the input sequence and combinations of the sensor and instrumentation errors were investigated. The results indicate that both the parameter accuracy and the corresponding measurement trajectory fit error can be significantly affected. Of the error sources considered, instrumentation lags and control measurement errors were found to be most significant.
    Schlagwort(e): AERODYNAMICS
    Materialart: Parameter Estimation Tech. and Appl. in Aircraft Flight Testing; p 261-280
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  • 48
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    Nonlinear parameter identification: Ballistic range experience applicable to flight testing (1974)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: The parameter identification scheme being used is a differential correction least squares procedure (Gauss-Newton method). The position, orientation, and derivatives of these quantities with respect to the parameters of interest (i.e., sensitivity coefficients) are determined by digital integration of the equations of motion and the parametric differential equations. The application of this technique to three vastly different sets of data is used to illustrate the versatility of the method and to indicate some of the problems that still remain.
    Schlagwort(e): AERODYNAMICS
    Materialart: Parameter Estimation Tech. and Appl. in Aircraft Flight Testing; p 191-195
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  • 49
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    Lyman-alpha imagery of Comet Kohoutek (1974)
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    Publikationsdatum: 2011-08-16
    Beschreibung: Electrographic imagery of Comet Kohoutek in the 1100-1500 A wavelength range was obtained from a sounding rocket on Jan. 8, 1974, and from the Skylab space station on 13 occasions between Nov. 26, 1973 and Feb. 2, 1974. These images are predominantly due to Lyman-alpha (1216 A) emission from the hydrogen coma of the comet. The rocket pictures have been calibrated for absolute sensitivity and a hydrogen production rate has been determined. However, the Skylab camera suffered degradation of its sensitivity during the mission, and its absolute sensitivity for each observation can only be estimated by comparison of the comet images with those taken by the rocket camera, with imagery of the geocoronal Lyman-alpha glow, of the moon in reflected Lyman-alpha, and of ultraviolet-bright stars. The rocket and geocoronal comparisons are used to derive a preliminary, qualitative history of the development of the cometary hydrogen coma and the associated hydrogen production rate.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Icarus; 23; Dec. 197
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  • 50
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    Interpretation of the anti-tail of Comet Kohoutek as a particle flow phenomenon (1974)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: The appearance of a 'sunward' spike, opposite in apparent orientation to the normal Type-II tail in Comet Kohoutek is interpreted as evidence for large particles ejected near perihelion. It is shown that the shape and orientation can be satisfactorily explained in this manner, after consideration of the increased mass flow at decreasing heliocentric distance. The apparent length of the spike can be a measure of the particle size and density, and a value of about 0.004 g/sq cm for the product of particle size and density fits the Skylab observations.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Icarus; 23; Dec. 197
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  • 51
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    A comment on gamma ray lines from He-4 (1974)
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    Publikationsdatum: 2011-08-16
    Beschreibung: It is pointed out that excited states of He-4 cannot produce gamma ray line emission of astrophysical significance, contrary to a recent suggestion of Reina et al. (1974). The only possible gamma-ray lines in He-4 are above 25 MeV, but their excitation cross sections appear to be so small that they are probably of little astrophysical significance.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astronomy and Astrophysics; 36; 2, No; Nov. 197
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  • 52
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    Violation of the Vogt-Russell theorem for homogeneous nondegenerate stars (1974)
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    Publikationsdatum: 2011-08-16
    Beschreibung: A systematic study is made of the number and types of solutions of the equilibrium equations of stellar structure, in the case of homogeneous stars of Population I over the mass range 2-1000 solar masses, with four different opacity representations. A variant of the usual fitting method permits the simultaneous investigation of convergence and tendency toward multiplicity of the solutions. Quadratic interpolation and extrapolation of Carson's new opacity tables produces a very large opacity at low temperatures that greatly affects the loose outer layers of massive stars, while leaving the cores practically unaffected. As a result, over a small mass range, well above 100 solar masses, triple solutions exist, always near an effective temperature of log Te = 4.73. A simple classification of the known exceptions to the Vogt-Russell theorem on the uniqueness of stellar structure is given.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal; 194; Dec. 15
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  • 53
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    Neutrino emission from plasmons in strong magnetic fields (1974)
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    Publikationsdatum: 2011-08-16
    Beschreibung: Neutrino pair emission from stellar interiors is investigated. The paper indicates that the proposed enhanced emission mode is a part of a transverse mode spectrum with a refraction index in the limit of infinity. It is concluded that in an astrophysical sense a very strong magnetic field does not have a significant effect on the emission rate of neutrinos from plasmons.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysics and Space Science; 31; Nov. 197
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    X rays predicted from flares of UV Ceti stars (1974)
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    Publikationsdatum: 2011-08-16
    Schlagwort(e): ASTROPHYSICS
    Materialart: Nature; 252; Dec
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  • 55
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    Evidence for a corona of beta Geminorum (1974)
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    Publikationsdatum: 2011-08-16
    Beschreibung: A spectrometer was used on the satellite Copernicus to observe a chromospheric L alpha emission from the K0 giant beta Gem at 1218.4 A. This emission appears to be in the corona at temperatures near 260,000 deg K, since the ion it is identified with requires 77.4 eV to be produced.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal; 193; Nov. 1
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    Tentative identification of U93.174 as the molecular ion N2H/+/ (1974)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: On the basis of a consideration of the rotation constant and the hyperfine structure together with the results of an ab initio structural calculation it is suggested that the three closely space new interstellar lines near 93.174 GHz reported by Turner (1974) might have been produced by the molecular ion N2H(+). It is pointed out that the identification of N2H(+) is reasonable also in terms of current ideas of interstellar chemistry.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal; 193; Oct. 15
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    Aerodynamics of jet flap and rotating cylinder flap STOL concepts (1974)
    In:  CASI
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    Publikationsdatum: 2012-05-22
    Beschreibung: The aerodynamic effectiveness of various propulsive lift concepts to provide for the low speed performance and control required for short takeoff and landing aircraft is discussed. The importance of the interrelationship between the propulsion system and aerodynamic components of the aircraft is stressed. The relative effectiveness of different lift concepts was evaluated through static and wind tunnel tests of various aerodynamic models and propulsion components, simulations of aircraft, and in some cases, flight testing of research aircraft incorporating the concepts under study. Results of large scale tests of lift augmentation devices are presented. The results of flight tests of STOL research aircraft with augmented jet flaps and rotating cylinder flaps are presented to show the steeper approach flight paths at low forward speeds.
    Schlagwort(e): AERODYNAMICS
    Materialart: AGARD V/STOL Aerodyn.; 6 p
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    Absolute radiometry and the solar constant (1974)
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    Publikationsdatum: 2011-08-16
    Beschreibung: A series of active cavity radiometers (ACRs) are described which have been developed as standard detectors for the accurate measurement of irradiance in absolute units. It is noted that the ACR is an electrical substitution calorimeter, is designed for automatic remote operation in any environment, and can make irradiance measurements in the range from low-level IR fluxes up to 30 solar constants with small absolute uncertainty. The instrument operates in a differential mode by chopping the radiant flux to be measured at a slow rate, and irradiance is determined from two electrical power measurements together with the instrumental constant. Results are reported for measurements of the solar constant with two types of ACRs. The more accurate measurement yielded a value of 136.6 plus or minus 0.7 mW/sq cm (1.958 plus or minus 0.010 cal/sq cm per min).
    Schlagwort(e): ASTROPHYSICS
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    An experimental test of the homogeneity of the interstellar medium (1974)
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    Publikationsdatum: 2011-08-16
    Beschreibung: Observations of nonthermal continuum radio emission at 750 MHz and hydrogen-line emission at 1420 MHz have been compared in order to test the extent to which cosmic-ray electrons, magnetic fields, and hydrogen gas coexist in the interstellar medium. If the interstellar medium is homogeneous in the sense that its constituents are mixed together and can interact, then regions of line and continuum emission should be spatially correlated. The measurements indicate that at most 28% of continuum emission in the Galaxy comes from such a homogeneous medium. The remaining nonthermal emission agrees in magnitude with the residual emission found by Berkhuijsen after subtraction of the polarized component of nonthermal emission. In addition, the data discussed here show that the major filamentary structures found in the two forms of emission rarely coincide spatially. Consequently, both the average and the exceptional structure in the medium indicate that the synchrotron-radiating magnetoplasma and the neutral hydrogen gas are not closely interacting in the present state of the medium.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal; 194; Dec. 1
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    Origin of fifteen cosmic dust particles intercepted by Pioneer 8 and 9 (1974)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: Consistent data for more than 8 years have been obtained from two identical cosmic dust particle experiments on board the space probes Pioneer 8 and 9. The two spacecraft are in direct heliocentric orbits with perihelia between 0.75 AU and 1.00 AU. On the basis of the data it is concluded that the majority of dust particles having elliptical orbits detected by the two space probes show orbital characteristics of Apollo group asteroids which originated from residual nuclei of short-period comets.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Nature; 252; Dec. 13
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    A generalized-capacity-matrix technique for computing aerodynamic flows (1974)
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    Publikationsdatum: 2011-08-16
    Beschreibung: A numerical generalized-capacity-matrix technique is developed for application to aerodynamic flow computations. This technique allows the very fast direct (noniterative) numerical elliptic solvers to be used in problems with arbitrary internal boundaries and with a wide class of boundary conditions, including numerical application of the Kutta condition on an airfoil without iteration. Accuracy, speed, and usefulness of the technique are demonstrated with linear problems for potential flows over airfoil shapes. The method's main advantages, however, can be exploited within iterative procedures for a variety of complex flow problems governed by systems of equations not necessarily elliptic or linear.
    Schlagwort(e): AERODYNAMICS
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    Fast direct numerical solution of the nonhomogeneous Cauchy-Riemann equations (1974)
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    Publikationsdatum: 2011-08-16
    Beschreibung: A fast direct (noniterative) 'Cauchy-Riemann Solver' is developed for solving the finite-difference equations representing systems of first-order elliptic partial differential equations in the form of the nonhomogeneous Cauchy-Riemann equations. The method is second-order accurate and requires approximately the same computer time as a fast cyclic-reduction Poisson solver. The accuracy and efficiency of the direct solver are demonstrated in an application to solving an example problem in aerodynamics: subsonic inviscid flow over a biconvex airfoil. The analytical small-perturbation solution contains singularities, which are captured well by the computational technique. The algorithm is expected to be useful in nonlinear subsonic and transonic aerodynamics.
    Schlagwort(e): AERODYNAMICS
    Materialart: Journal of Computational Physics; 15; May 1974
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  • 63
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    Estimation of longitudinal aerodynamic coefficients and comparison with wind-tunnel values (1974)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: Some recent experience at Ames Research Center in the estimation of aerodynamic coefficients for the Lear-Jet and the Augmentor Wing Jet STOL Research Aircraft is reviewed. The coefficients estimated from flight data are compared with values based on large-scale wind-tunnel tests. The results obtained by the regression and quasilinearization identification techniques are also compared. The regression method generally provides the lower standard deviation in the coefficient estimates and provides the better fit to the wind-tunnel values. The addition of nonlinear terms in the aerodynamic equations decreases the difference between the estimated and measured time histories but also increases the standard deviation in the estimated coefficient values.
    Schlagwort(e): AERODYNAMICS
    Materialart: Parameter Estimation Tech. and Appl. in Aircraft Flight Testing; p 125-148
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  • 64
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    Vortex-induced heating to cone flaps at Mach 6 (1974)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: Discussion of the local heating effect on the lee-side control flaps of supersonic configurations due to the interaction between vortices and leeward control surfaces at an angle of attack. Considerations are given for an appropriate positioning of control flaps to alleviate such interactions and the resulting thermal effect. Tests are carried out on a sharp right circular cone with two types of flap configurations in a study of oil flow patterns about the cone at selected angles of attack. Splitting of flaps and moving them to positions away from the symmetry plane did reduce the heating but also reduced the average flap pressure and increased flow complexity.
    Schlagwort(e): AERODYNAMICS
    Materialart: Journal of Spacecraft and Rockets; 11; Mar. 197
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  • 65
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    An improved static probe design (1974)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: A new static probe design is described in which the static holes are located much closer to the tip than in conventional probes. The new probe shows promise for use in some situations where conventional probes become highly inaccurate. An additional advantage of the new design is that, when used in static pressure survey rakes, the probes can be located much closer together than in conventional designs and still ensure that disturbances from neighboring probe tips do not affect the static readings.
    Schlagwort(e): AERODYNAMICS
    Materialart: AIAA Journal; 12; Apr. 197
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  • 66
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    Vortex-induced heating to a cone-cylinder body at Mach 6 (1974)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: Presented data on vortex-induced heating in a cone-cylinder body at Mach 6 show that the most severe heating need not occur as a result of the interaction of the primary vortices with the lee surface, even though this interaction produces a large, well-defined featherline oil smear. It is pointed out that the severity of vortex-induced heating is extremely sensitive to Reynolds number and geometry and that there exists a 'threshold Reynolds number' below which vortex-induced heating decreases abruptly.
    Schlagwort(e): AERODYNAMICS
    Materialart: Journal of Spacecraft and Rockets; 11; Feb. 197
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  • 67
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    Simulation of real-gas effects for Mars entry (1974)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: The changes in aerodynamic characteristics due to real-gas effects associated with high speed flight (characterized by large shock density ratios) are primarily the result of changes in surface pressures acting on the forebody. The surface pressures are affected by a change in shock density ratio (real-gas effects) in two ways. First, the level of pressure at the stagnation point relative to freestream dynamic pressure is changed, and second, the distribution of surface pressure relative to stagnation-point pressure is changed. The density-ratio effect on the stagnation point pressure level can be estimated by considering the flow of a perfect gas about a blunt body.
    Schlagwort(e): AERODYNAMICS
    Materialart: Journal of Spacecraft and Rockets; 11; Jan. 197
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  • 68
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    V/STOL aerodynamics: A review of the technology (1974)
    In:  CASI
    Details
    Publikationsdatum: 2012-05-22
    Beschreibung: An analysis of the development and technological applications of V/STOL aircraft is presented. The use of V/STOL aircraft to overcome the limitations of conventional aircraft is discussed. The aspects of V/STOL aircraft which are considered are: (1) economic penalties of propulsive lift, (2) advantages of propulsive lift, (3) potential improvements in V/STOL aircraft, (4) the aerodynamics of V/STOL aircraft, and (5) proposals for additional research in V/STOL development.
    Schlagwort(e): AERODYNAMICS
    Materialart: AGARD V/STOL Aerodyn.; 13 p
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  • 69
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    Upper atmospheres and diagnostic measurements (1974)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: Candidate space missions to study the temperature profiles, and ratios of hydrogen to helium in outer planet atmospheres are discussed in terms of scientific payloads for optical occultation, radio occultation, and thermometer measurements.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Dynatrend, Inc. Proc. of Outer Planet Probe Technol. Workshop, Sect. 1 through 11; 8 p
    Format: application/pdf
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  • 70
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    Estimates of the size of particles in Saturn's rings and their cosmogonic implications (1974)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: Near infrared ice band measurements, radar and radio observations, and implications of the size estimates of particles in Saturn's rings are discussed. The measurements are compared to the Poynting-Robetson effect and a possible mechanism by which the size of the particles may significantly change after the initial formulation of the material in the rings is proposed.
    Schlagwort(e): ASTROPHYSICS
    Materialart: The Rings of Saturn; p 107-123
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  • 71
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    The atmosphere of the rings of Saturn (1974)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: Outgassing of H and OH from Saturn's rings and the possibility of detecting it are examined. The source gas around the rings is computed after which the products of ice, H2O, H, and OH and the physical mechanisms that produce these species are given. Production rates for the ice products are discussed.
    Schlagwort(e): ASTROPHYSICS
    Materialart: NASA, Washington The Rings of Saturn; p 125-129
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  • 72
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    Distribution and size of elements of Saturn's rings as inferred from 12-cm radar observations (1974)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: A 64m radar antenna was used to observe Saturn's rings at 12.6 cm wavelength, with reduced Doppler spread. The results show a positive radar return corresponding to about a 60 percent return from an isotropic scatterer with the projected area of the rings, allowing for the Cassini division. A radar spectrogram of the rings is shown with power density plotted against Doppler frequency shift.
    Schlagwort(e): ASTROPHYSICS
    Materialart: NASA, Washington The Rings of Saturn; p 73-82
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  • 73
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    Variations in the infrared brightness temperature of Saturn's rings (1974)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: After adjusting for the decreased Sun-Saturn distance and adjusting all measurements to B ring values only, it is shown that the temperature variations are not as large as was thought. Various models of the multilayer agglomerate of particles of Saturn's rings are evaluated. It is recommended that the difference between the 11 and 20 micron brightness temperatures should be explained by a satisfactory model.
    Schlagwort(e): ASTROPHYSICS
    Materialart: NASA, Washington The Rings of Saturn; p 65-72
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  • 74
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    Saturn's ring particles and space vehicle design (1974)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: Spacecraft design is discussed for probing Saturn's rings. Ring particles are also considered, emphasizing material outside of ring A and the hazard this might imply to a spacecraft crossing the ring plane beyond ring A.
    Schlagwort(e): ASTROPHYSICS
    Materialart: NASA, Washington The Rings of Saturn; p 29-38
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  • 75
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    Ring particle sizes and composition derived from eclipse cooling curves and reflection spectra (1974)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: The probable chemistry of the Saturn rings is reviewed. Reflectance spectra for H20 and NH3 frosts and Saturn's rings are compared, along with temperature dependence of 1.6 microns water frost feature. The reflection spectra of Galilean satellite J2 and water frost are also reviewed.
    Schlagwort(e): ASTROPHYSICS
    Materialart: NASA, Washington The Rings of Saturn; p 51-63
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  • 76
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    Model of Saturn's rings that satisfies the observed phase curve for optical scattering (1974)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: The effects of multiple anisotropic scattering were calculated, including the solar penumbra effect for shadowing computations. The classical model was matched to observations, including the wavelength dependence, by varying the particle albedo as a function of wavelength. A scattering diagram is also presented showing the relative amount of primary and higher-order scattering necessary to match the B ring brightness and the shape of the phase curve.
    Schlagwort(e): ASTROPHYSICS
    Materialart: NASA, Washington The Rings of Saturn; p 17-28
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  • 77
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    Structure of Saturn's rings: Optical and dynamical considerations (1974)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: The photometric phase curves of Saturn's rings are considered, as well as a conflict between dynamical and photometric models of the rings. The dependence of ring brightness on angular separation of the earth and sun as viewed from Saturn is discussed. The nonlinear brightness surge is interpreted. Some quantitative calculations were carried out for bodies in and near the asteroidal belt. Predicted density profiles of the ring obtained with Mimas in an eccentric orbit and in a circular orbit are also included.
    Schlagwort(e): ASTROPHYSICS
    Materialart: NASA, Washington The Rings of Saturn; p 3-15
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  • 78
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    A general purpose stabilised balloon platform (1974)
    In:  CASI
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    Publikationsdatum: 2016-06-07
    Beschreibung: The development of a three axis stabilized balloon platform capable of being operated in three modes of increasing accuracy is discussed. The system relies on angular motion sensing for primary feedback with linear accelerometers, magnetometers, and a star sensor for positional information. When under primary control the system will acquire and stabilize on any accessible part of the celestial sphere. A video verification system is included to provide pointing confirmation. Under improved accuracy control, the star sensor is used to lock onto a target star.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA. Ames Res. Center Telescope Systems for Balloon-Borne Res.; p 284-293
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  • 79
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    Air Force Cambridge Research Laboratories balloon operations (1974)
    In:  CASI
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    Publikationsdatum: 2016-06-07
    Beschreibung: The establishment and functions of the AFCRL balloon operations facility are discussed. The types of research work conducted by the facility are defined. The facilities which support the balloon programs are described. The free balloon and tethered balloon capabilities are analyzed.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA. Ames Res. Center Telescope Systems for Balloon-Borne Res.; p 160-164
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  • 80
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    Balloon platform for extended-life astronomy research (1974)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: A configuration has been developed for a long-life balloon platform to carry pointing telescopes weighing as much as 80 pounds (36 kg) to point at selected celestial targets. A platform of this configuration weighs about 375 pounds (170 kg) gross and can be suspended from a high altitude super pressure balloon for a lifetime of several months. The balloon platform contains a solar array and storage batteries for electrical power, up and down link communications equipment, and navigational and attitude control systems for orienting the scientific instrument. A biaxial controller maintains the telescope attitude in response to look-angle data stored in an on-board computer memory which is updated periodically by ground command. Gimbal angles are computed by using location data derived by an on-board navigational receiver.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA. Ames Res. Center Telescope Systems for Balloon-Borne Res.; p 136-144
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  • 81
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    An orientable, stabilized balloon-borne gondola for around-the-world flights (1974)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: A system capable of pointing a balloon-borne telescope at selected celestial objects to an accuracy of approximately 10 arc minutes for an extended period (weeks to months) without reliance on telemetry is described. A unique combination of a sun/star tracker, an on-board computer, and a gyrocompass is utilized for navigation, source acquisition and tracking, and data compression and recording. The possibilities for intelligent activities by the computer are also discussed.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA. Ames Res. Center Telescope Systems for Balloon-Borne Res.; p 71-80
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  • 82
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    Experimental and analytical studies in tilt-rotor aeroelasticity (1974)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: An overview of an experimental and analytical research program underway for studying the aeroelastic and dynamic characteristics of tilt-rotor VTOL aircraft is presented. Selected results from several investigations of scaled models in the transonic dynamics tunnel, as well as some results from a test of a flight-worthy proprotor in the full-scale wind tunnel are shown and discussed with a view toward delineating various aspects of dynamic behavior peculiar to proprotor aircraft. Included are such items as proprotor/pylon stability, whirl flutter, gust response, and blade flapping. Theoretical predictions are shown to be in agreement with the measured stability and response behavior.
    Schlagwort(e): AERODYNAMICS
    Materialart: Its Rotorcraft Dyn.; p 171-184
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  • 83
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    Theory and comparison with tests of two full-scale proprotors (1974)
    In:  CASI
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    Publikationsdatum: 2016-06-07
    Beschreibung: A nine degrees-of-freedom theoretical model was developed for investigations of the dynamics of a proprotor operating in high inflow axial flight on a cantilever wing. The theory is described, and the results of the analysis are presented for two proprotor configurations: a gimballed, stiff-inplane rotor, and a hingeless, soft-inplane rotor. The influence of various elements of the theory are discussed, including the modeling used for the blade and wing aerodynamics, and the influence of the rotor lag degree of freedom. The results from full-scale tests of the two proprotors are presented and compared with the theoretical results.
    Schlagwort(e): AERODYNAMICS
    Materialart: Its Rotorcraft Dyn.; p 159-169
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  • 84
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    Rotating stars (1974)
    In:  CASI
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    Publikationsdatum: 2016-06-07
    Schlagwort(e): ASTROPHYSICS
    Materialart: JPL Proc. of the Intern. Colloq. on Drops and Bubbles, Vol. 1; p 11-34
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  • 85
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    The fission theory of binary stars (1974)
    In:  CASI
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    Publikationsdatum: 2016-06-07
    Schlagwort(e): ASTROPHYSICS
    Materialart: JPL Proc. of the Intern. Colloq. on Drops and Bubbles, Vol. 1; p 1-10
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  • 86
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    Comparison of the experimental aerodynamic characteristics of theoretically and experimentally designed supercritical airfoils (1974)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-28
    Beschreibung: A lifting airfoil theoretically designed for shockless supercritical flow utilizing a complex hodograph method has been evaluated in the Langley 8-foot transonic pressure tunnel at design and off-design conditions. The experimental results are presented and compared with those of an experimentally designed supercritical airfoil which were obtained in the same tunnel.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-TM-X-3082 , L-9548 , NAS 1.15:X-3082
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  • 87
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    A study of the nonlinear aerodynamics of bodies in nonplanar motion (1974)
    In:  CASI
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    Publikationsdatum: 2019-06-27
    Beschreibung: Concepts from the theory of functionals are used to develop nonlinear formulations of the aerodynamic force and moment systems acting on bodies in large-amplitude, arbitrary motions. The analysis, which proceeds formally once the functional dependence of the aerodynamic reactions upon the motion variables is established, ensures the inclusion, within the resulting formulation, of pertinent aerodynamic terms that normally are excluded in the classical treatment. Applied to the large-amplitude, slowly varying, nonplanar motion of a body, the formulation suggests that the aerodynamic moment can be compounded of the moments acting on the body in four basic motions: steady angle of attack, pitch oscillations, either roll or yaw oscillations, and coning motion. Coning, where the nose of the body describes a circle around the velocity vector, characterizes the nonplanar nature of the general motion.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-TR-R-421 , A-5057
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  • 88
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    Limits on the neutral hydrogen content of Coma and other clusters of galaxies (1974)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astronomy and Astrophysics; 36; 3, De; Dec. 197
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  • 89
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    Binary stellar winds (1974)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: Stellar winds from a binary star will interact with each other along a contact discontinuity. We discuss qualitatively the geometry of the flow and field resulting from this interaction in the simplest case where the stars and winds are identical. We consider the shape of the critical surface (defined as the surface where the flow speed is equal to the sound speed) as a function of stellar separation and the role of shock waves in the flow field. The effect of stellar spin and magnetic sectors on the field configuration is given. The relative roles of mass loss and magnetic torque in the evolution of orbital parameters are discussed.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysics and Space Science; 31; Dec. 197
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  • 90
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    A search for microwave emission from CH in Comet Kohoutek /1973f/ (1974)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: A search was conducted for the three 9-cm transitions of the ground state Lambda-doublet of CH in comet Kohoutek, using the CSIRO 64-m radio telescope and the Onsala Space Observatory's 25.6-m telescope. No lines were detected during the observing periods, and upper limits are given for the corresponding antenna temperatures.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Icarus; 23; Dec. 197
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  • 91
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    Molecule searches in Comet Kohoutek /1973f/ at microwave frequencies (1974)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: Nine transitions of the possible parent molecules H2O, NH3, CH3OH and N2O as well as the OH radical were searched for in Comet Kohoutek (1973f) in the frequency range 22.2-25.2 GHz. These molecules were not detected, but the upper limits for the optical depth, mean column density and the production rate are derived for each of the molecules. These results are discussed and compared with the reported detections of HCN and CH3CN emission and OH absorption.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Icarus; 23; Dec. 197
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  • 92
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    On the nature of the anti-tail of Comet Kohoutek /1973f/. I - A working model (1974)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: The model derived for the anti-tail of Comet Kohoutek describes it as a flat formation, confined essentially to the comet's orbit plane and composed of relatively heavy particles (mostly in the size range 0.1-1 mm) whose motions are controlled by solar gravity and solar radiation pressure. Almost all the material was produced by the comet before perihelion at a rate about an order of magnitude higher than for Comets Arend-Roland and Bennett. The latent heat of vaporization of the particle material is estimated at 40-45 kcal/mole or higher.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Icarus; 23; Dec. 197
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  • 93
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    Simple methods for determining the virtual origin of turbulent boundary layers in hypersonic flow on sharp-edged flat plates (1974)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: Two methods for determining the virtual origin of turbulent boundary layers in hypersonic flow are evaluated. The results of the analyses are restricted to wind-tunnel models having sharp-edged surfaces with zero or small pressure gradients. Virtual origin and skin friction estimates from these two methods are compared with values from a base method for which the virtual origin is calculated from the measured momentum thickness at a station downstream of boundary layer transition.
    Schlagwort(e): AERODYNAMICS
    Materialart: ASME PAPER 74-APM-V
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  • 94
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    An upper limit on the evolution of carbon monoxide from Comet Kohoutek (1974)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: An upper limit on the rate of evolution of CO from Comet Kohoutek has been obtained from a search for resonant scattering of sunlight near 4.7 microns. The observations were made approximately two months after perihelion. The rate of evolution of CO at that time was apparently less than that of CH3CN observed before perihelion.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Icarus; 23; Dec. 197
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  • 95
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    Interstellar carbon I lines in zeta Ophiuchi (1974)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: With two f-values of C I lines obtained from the spectra of zeta Pup and gamma(2) Vel, it is shown that the interstellar C I spectrum in zeta Oph obeys an optical-depth relation similar to that for Na I, and the relative strengths of 19 multiplets are determined from this relation. The dominant processes which excite neutral carbon are used to calculate populations of the fine-structure levels as functions of the density of H nuclei and the temperature, and evidence is found that the C I lines are formed in the dense cloud in front of zeta Oph at a heliocentric velocity of -14.4 km/s. It is noted that the observed column-density ratios of the neutral carbon fine-structure levels lead to a total H nuclei density of about 220 to 660 per cu cm, while the electron density and observed C(+) abundance indicate a value of 10,000 per cu cm, with a 0.05 pc thick gas layer.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astronomy and Astrophysics; 37; 2, De; Dec. 197
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  • 96
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    CNO abundances and hydrodynamic models of the nova outburst. III - 0.5 solar mass models with enhanced carbon, oxygen, and nitrogen (1974)
    In:  Other Sources
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: Consideration of the evolution of thermonuclear runaways in the hydrogen-rich envelopes of 0.5 solar mass carbon-oxygen white dwarfs. The larger radii of these stars, compared with the 1.00 solar mass white dwarfs, results in a lesser degree of degeneracy at the same depth in the star. Four models of luminosity with .00355 solar luminosity, differing only in the initial abundances of C-12, N-14, and O-16, are presented. The degree of enhancement required to produce mass ejection, and thereby a nova-type outburst, is greater than for the 1.00 solar mass model. Nevertheless, the evolution of the 0.5 solar mass model that ejected material is very similar to that of the 1.00 solar mass models, and it also ejects significant amounts of C-13, N-15, and O-17 into the interstellar medium. The 0.5 solar mass outburst is considerably less intense than the 1.00 solar mass outburst (even under optimum conditions), and this lower mass behavior is interpreted as associated with the observed outburst of the slowest novae.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal; 192; Sept. 15
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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  • 97
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    Ultraviolet spectrophotometry of Sirius from Gemini 12 (1974)
    In:  Other Sources
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: The spectral energy distribution of Sirius between 2500 and 3700 A at a resolution of 7 A is obtained from plates taken on Gemini 12. The agreement with other observations and the most recent line-blanketed model atmospheres is good. The equivalent width of the Mg II doublet near 2800 A is 6.0 A, if the continuum level is represented by regions near 2650 and 2910 A. This is consistent with expectations for a hot Am star and implies line blocking of up to 15% in this wavelength region.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal; 192; Sept. 15
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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  • 98
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    Forward slanted slot throat stability bypass to increase the stable airflow range of a Mach 2.5 inlet with 60 percent internal contraction (1974)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: The results of an experimental investigation to increase the stable airflow operating range of a supersonic mixed-compression inlet are presented. Two forward-slanted slot stability-bypass entrance configurations were tested. In terms of diffuser-exit corrected airflow, a large inlet stable airflow range of 18.5 percent was obtained with the superior configuration if a constant pressure was maintained in the bypass plenum. Limited unstart angle-of-attack data are presented.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-TM-X-2973 , E-7706
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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  • 99
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    Effect of screen-induced total-pressure distortion on axial-flow compressor stability (1974)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: An experimental investigation was made to determine the effects of screen-induced total-pressure distortions on two J85-GE-13 turbojet engines. Results were compared to those from a previous program run with a third engine. All compressors were found to be sensitive to a critical angle of circumferential distortion equal to 60 deg., and they all adhered closely to the parallel compressor model. The sensitivity of compressor exit pressure to virtually any type of distortion pattern can be determined by defining stall lines for undistorted, hub radial distorted, and tip radial distorted inflows. The effect of multiple sectors of circumferential distortion is defined.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-TM-X-3017 , E-7792
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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  • 100
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    Combined Quadrupole-dipole Model for Inlet Flow Distortion Noise from a Subsonic Fan (1974)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: A combined quadrupole-dipole model has been developed for the noise generated by inlet flow distortion in a subsonic fan. A formula is derived for the total upstream-radiated acoustic power in each tone as a function of the design parameters of the fan and the properties of the inlet flow distortion. Numerical results are obtained for values of the parameters corresponding to various quiet fans. The analysis is compared with noise measurements taken on a 51-cm (20-in.) diameter research fan as well as with those taken on a number of full-scale fan stages. Fairly good agreement was obtained. It should therefore be possible to use this model to study the noise-reduction potential of the various fan design parameters.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-TN-D-7676 , E-7881
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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