The photometric functions of Phobos and Deimos. I - Disc-integrated photometry
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Noland, M.↗
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TRASYS: Checkout of accuracy of direct irradiation calculations for discs, trapezoids, cones, and circular paraboloids
Results of the direct irradiation link of the TRASYS program are evaluated. Several surface configurations were investigated. The accuracy of the results was examined for simple cases where the answers were analytically known. By varying an accuracy factor in the program, the amount of computer time needed to achieve different degress of accuracy was determined.
Mackeen, R. C.↗
On the phase relationship between the energetic particle flux modulation and current disc penetrations in the Jovian magnetosphere - Pioneer 10 inbound
The surface defined by the locus of field minima along field lines for an unterminated Jovian model magnetosphere is found to coincide with the surface of the model current disk which provides a good fit to the data. However, when the model is terminated by means of magnetopause currents, preservation of the fit by modifying the current distribution near the outer edge of the disk causes the minimum absolute magnetic field surface to bifurcate. Energetic electron flux time profiles that are based upon such a minimum absolute magnetic field configuration are found to be qualitatively consistent with the inbound Pioneer 10 data.
Jones, D. E.↗
Viscosity in accretion discs
Both HerX-1 and SS433 may contain accretion disks slaved to a precessing companion star. If so, it is possible to bound the effective viscosity in these disks. The results, in terms of the disk parameter alpha, are lower bounds of 0.01 for HerX-1 and of 0.1 for SS433.
Katz, J. I.↗
Modeling Jupiter's current disc - Pioneer 10 outbound
A model of the magnetic field of the Jovian current disk is presented. The model uses Euler functions and the Biot-Savart law applied to a series of concentric, but not necessarily coplanar current rings. It was found that the best fit to the Pioneer 10 outbound perturbation magnetic field data is obtained if the current disk is twisted, and also bent to tend toward parallelism with the Jovigraphic equator. The inner and outer radii of the disk appear to be about 7 and 150 Jovian radii, respectively; because of the observed current disk penetrations, the bent disk also requires a deformation in the form of a bump or wrinkle whose axis tends to exhibit spiraling. Modeling of the azimuthal field shows that it is due to a thin radial current sheet, but it may actually be due in large part to penetration of a tail current sheet as suggested by Voyager observations.
Jones, D. E.↗
NASTRAN level 16 programmer's manual updates for aeroelastic analysis of bladed discs
The programming routines for the NASTRAN Level 16program are presented. Particular emphasis is placed on its application to aeroelastic analyses, mode development, and flutter analysis for turbomachine blades.
Gallo, A. M.↗
Equatorial disc and dawn-dusk currents in the frontside magnetosphere of Jupiter - Pioneer 10 and 11
Observations by Pioneer 10 and 11 show that the strongest azimuthal fields are observed near the dawn meridian (Pioneer 10) while the weakest occur near the noon meridian (Pioneer 11), suggesting a strong local time dependence for the corresponding radial current system. Modeling studies of the radial component of the field observed by both spacecraft suggest that the corresponding azimuthal current system must also be a strong function of local time. Both the azimuthal and the radial field component signatures exhibit sharp dips and reversals, requiring thin radial and azimuthal current systems. There is also a suggestion that these two current systems either are interacting or are due, at least in part, to the same current. It is suggested that a plausible current model consists of the superposition of a thin, local-time-independent azimuthal current system plus the equatorial portion of a tail-like current system that extends into the dayside magnetosphere.
Jones, D. E.↗
New large-scale properties of the galactic gamma radiation observed by COS-B in the context of the diffuse emission within the galactic disc
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Mayer-Hasselwander, H. A.↗
Aurora on Uranus - A Faraday disc dynamo mechanism
A mechanism is proposed whereby the solar wind flowing past the magnetosphere of Uranus causes a Faraday disk dynamo topology to be established and power to be extracted from the kinetic energy of rotation of Uranus. An immediate consequence of this dynamo is the generation of Birkeland currents that flow in and out of the sunlit polar cap with the accompanying production of polar aurora. The power extracted from planetary rotation is calculated as a function of planetary dipole magnetic moment and the ionospheric conductivity of Uranus. For plausible values of ionospheric conductivity, the observed auroral power requires a magnetic moment corresponding to a surface equatorial field of the order of 4 Gauss, slightly larger than the value 1.8 Gauss given by the empirical 'magnetic Bodes law'.
Hill, T. W.↗
A user's view of optical disc applications
An overall space information system is considered. It is found that data storage is required in all elements of the system with the possible exception of the wideband communication link. The data capture facility is the first ground facility to handle space-acquired data. A typical nine-day Spacelab mission is expected to generate up to 10 to the 13th bits of data. The current storage medium for this data is approximately 4000 magnetic tapes. It is pointed out that optical disk storage provides an attractive alternative to magnetic disk and tape storage. Options to install an optical disk storage system in the GSFC data capture facility in the 1986 time frame are evaluated by NASA. Attention is given to data capture and data base applications, onboard data storage applications, and numerical computation applications.
Holcomb, L. B.↗
Diffusion instability in a bimodal disc
A simplified model of radial diffusion in a planetary disk with a bimodal size distribution is presented. The large particle component excites the small particles' dispersion velocity via gravitational scattering. The resulting small particle viscous stress goes through a maximum near optical depth = sq root 3. Such a stress profile promotes the development of high and low optical depth zones. The resulting ringlet appearance is due primarily to the distribution of small particles, which produce most of the optical depth but may constitute only a minor portion of system mass.
Ward, W. R.↗
Structure of air shower disc near the core
The longitudinal structure of the air shower disk is studied by measuring the arrival time distributions of air shower particles for showers with electron size in the range 3.2 x 10 to the 5.5. power to 3.2 x 10 to the 7.5 power in the Akeno air-shower array (930 gcm squared atmospheric depth). The average FWHM as a parameter of thickness of air shower disk increases with core distances at less than 50m. AT the present stage, dependence on electron size, zenith angle and air shower age is not apparent. The average thickness of the air shower disk within a core distance of 50m could be determined by an electromagnetic cascade starting from the lower altitude.
Inoue, N.↗
The thickness of the shower disc as observed in showers produced by primaries above 10 (19)eV
The thickness of the shower disk has been measured in showers initiated by primaries of energy to 10 the 19th power eV using the large area water Cerenkov detectors of the Haverah Park array. Results are presented which (1) provide supporting evidence for the accuracy of analysis procedures in giant showers, (2) offer an evaluation of the mini-array technique for the detection of giant showers and (3) extend earlier work on developmental fluctuations above 10 to the 19th power eV.
Lawrence, M. A.↗
Gamma radiation effects on the dynamic fatigue measurements of glass discs
Circular specimens of low iron soda lime silicate glass were blasted with grit after having a circular notch etched into their centers. After separation into two groups, one group was exposed to gamma radiation. The fracture strengths of all samples were then tested by the biaxial technique, i.e., specimens were balanced on three balls and loaded in the center by a piston. The irradiated samples had received a 140,000 Gy dose from a Co-60 source. An enhanced interaction between the ambient moisture and the grit-blasted central notch was observed in the irradiated samples, which displayed accelerated corrosion.
Ananaba, T. O. J.↗
The dynamics of a flexible bladed disc on a flexible rotor in a two-rotor system
This paper describes the development of the analysis of the transient dynamic response of a bladed disk on a flexible rotor. The rotating flexible bladed disk is considered as a module in a complete turbine engine structure. The analysis of the flexible bladed disk (FBD) module is developed for the non-equilibrated one-diameter axial mode. The FBD motion is considered as a sum of two standing axial waves constrained to the rotor. The FBD is coupled inertially and gyroscopically to its rotor support, and indirectly through connecting elements, to the adjacent rotor and/or other supporting structures. Incorporated in the basic Turbine Engine Transient Response Analysis program (TETRA), the FBD module is demonstrated with a two-rotor model where the FBD can be excited into resonance by an unbalance in the adjacent rotor and at a frequency equal to the differential rotor speed. The FBD module also allows the analysis of two flexible bladed disks in the same rotor.
Gallardo, V. C.↗
New high-resolution rocket-ultraviolet filtergrams of the solar disc
A rocket-borne solar ultraviolet telescope named Transition Region Camera was launched successfully for the third on July 13, 1982. High quality calibrated photographic images of the sun were obtained at Lyman alpha and in the continuum at 160 nm and 220 nm. The angular resolution achieved is better than one arcsec. A flare, active regions, sunspots, the 8 Mm mesostructure, the chromospheric network, bright UV grains and coronal loops were observed during the flight. The results are presented and the evolution with height in the solar atmosphere of the various structures observed is followed from one wavelength to the other, showing distinct differences. The value of the field's intensity of magnetic flux tubes is deduced from the observations.
Foing, B.↗
Flow-induced morphological instabilities - The rotating disc
The morphological stability of a rotating and solidifying disk is investigated under the assumption that delta, the thickness of the viscous boundary layer, is much larger than delta(c), the thickness of the solute boundary layer. It is found that axisymmetric disturbances with wavelengths comparable to delta respond to nonparallel flow effects and have stability characteristics quite different from disturbances in a parallel flow. These long waves are unstable because of the nonparallel flow and would decay without it. This analysis thus identifies a new mechanism of morphological change induced by flow.
Brattkus, K.↗
Viscous pulsational instability of the transonic region of isothermal geometrically thin accretion discs. I - Analytical results
Viscous instability of the transonic region of the conventional geometrically thin alpha-type accretion disks is examined analytically. For simplicity, isothermal disks and isothermal perturbations are assumed. It is found that when the value of alpha is larger than a critical value the disk is unstable against two types of perturbations. One is local propagating perturbations of inertial acoustic waves. Results suggest the possibility that unstable perturbations develop to overstable global oscillations which are restricted only in the innermost region of the disk. The other is standing growing perturbations localized just at the transonic point. The cause of these instabilities is that the azimuthal component of the Lagrangian velocity variation associated with the perturbations becomes in phase with the variation of the viscous stress force. Because of this phase matching work is done on perturbations, and they are amplified.
Kato, Shoji↗