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61.
62.
Herbert A. Beebe 《Solar physics》1971,17(2):304-315
The formation of the solar Caii K-line core is studied under the assumption of a two component chromosphere for many atmosphere models, which are tested by comparing observed and calculated average intensity profiles at several places on the solar disk. Non-LTE-line profile calculations are made using model atoms of two and three bound levels while the value and depth of the temperature minimum and turbulent velocity gradient are varied. A critique of several broad types of models is provided.Limb darkening of the entire core, a K1 radiation temperature of 4300 K and increasing limbward separation of the K2 peaks are predicted by a combination of a cool component, covering 90% of the solar disk, and a hot component, representing the bright calcium network. The optimum cool component is characterized by a 4200 K temperature minimum and low ( 1 km/sec) microturbulent velocities. The hot component begins its outward temperature rise in the photosphere at 4300 K and is never more than 500 K hotter than the cool component.Publications of the Goethe Link Observatory, Indiana University, No. 116.Presently at New Mexico State University, Las Cruces, New Mexico. 相似文献
63.
Earlier analyses of the Pioneer 8 and 9 experimental meteoroid data have shown that the detectors on these two spacecraft are intercepting meteoroids with hyperbolic orbital parameters. It is shown in this paper that these results are entirely consistent with and, indeed, to be expected from other observations of the interplanetary meteoroid complex. Collisional breakup of meteoroids and post-collision radiation pressure modification of their orbits is found to be a sufficient cause for the observed results. Details of the calculations as well as of the results are presented. 相似文献
64.
Copper concentrations in surface waters off the southeastern United States coast range from 0.02 to 0.33 μg/kg (0.3–5.2 nmol/kg). Mean concentrations are lowest in Onslow Bay (0.07 μg/kg) and highest over the Blake Plateau (0.20 μg/kg). An explanation, compatible with the hydrography and hydrodynamics of the area, is proposed for the observed regional variations. 相似文献
65.
Testing the theoretical notion that differences in entrepreneurial skill can enhance the viability of a poor location or detract from the qualities of a good location, this study reviews the historical experience of a number of retailing establishments operated by different firms at the same sites. The ultimate success of stores that had done poorly under previous management tends to confirm that a location is “good'’only so long as the retailer employs effective merchandising and operating policies. 相似文献
66.
Herbert Knothe 《Celestial Mechanics and Dynamical Astronomy》1969,1(1):36-45
In an axially symmetric three-dimensional Riemann-spaceg ik(u 1,u 2)?u 3 represents the cyclic parameter-, a gravitational potential ?(u 1,u 2) is given. For all masspoints with equal total energy and equal angular momentum there exists a function Ψ(u 1,u 2) by means of which the equations of motion can be reduced to a simple ordinary second-order differential equation. The function ? can be interpreted as the velocity with which the masspoint moves in the two-dimensional spaceu 1,u 2. Of particular interest is the case where the spaceu 1,u 2,u 3 is Euclidean. Ifu 1,u 2 are Cartesian coordinates in a planeu 3=const., and if the tangent vector of the trajectoryu 1(t)u 2(t) has the components cosω, sinω it is shown that the triple integral $$\smallint \smallint \smallint \psi du^1 du^2 d\omega $$ is an invariant integral in Cartan's sense, in other words, if the integral is extended over a domain in a meridian plane at timet=0, it keeps its value at any time. 相似文献
67.
68.
Ohne Zusammenfassung 相似文献
69.
70.
Marthinus Cloete Rodger J. Hart Herbert K. Schmid Martyn Drury Chris M. Demanet K. Vijaya Sankar 《Contributions to Mineralogy and Petrology》1999,137(3):232-245
Submicroscopic opaque particles from highly shocked granite-gneisses close to the core of the Vredefort impact structure
have been investigated by means of micro-analytical techniques with high spatial resolution such as electron diffraction,
orientation contrast imagery and magnetic force microscopy. The opaque particles have been identified as nano- to micro-sized
magnetite that occur in several distinct modes. In one sample magnetite occurs along relict planar deformation features (PDFs)
in quartz, generally accepted as typical shock lamellae. The magnetite particles along shock lamellae in quartz grains virtually
all show uniform crystallographic orientations. In most instances, the groups of magnetite within different quartz grains
are systematically misorientated such that they share a subparallel <101> direction. The magnetite groups of all measured
quartz grains thus appear to have a crystallographic preferred orientation in space. In a second sample, orientations of magnetite
particles have been measured in microfractures (non-diagnostic of shock) of quartz, albite and in the alteration halos, (e.g.
biotite grains breaking down to chlorite). The crystallographic orientations of magnetite particles are diverse, with only
a minor portion having a preferred orientation. Scanning electron microscopy shows that magnetite along the relict PDFs is
invariably associated with other microcrystalline phases such as quartz, K-feldspar and biotite. Petrographic observations
suggest that these microcrystalline phases crystallized from locally formed micro-melts that intruded zones of weakness such
as microfractures and PDFs shortly after the shock event. The extremely narrow widths of the PDFs suggest that heat may have
dissipated rapidly resulting in melts crystallizing relatively close to where they were generated. Magnetic force microscopy
confirms the presence of magnetic particles along PDFs. The smallest particles, <5 μm with high aspect ratios 15:1 usually
exhibit intense, uniform magnetic signals characteristic of single-domain magnetite. Consistent offsets between attractive
and repulsive magnetic signals of individual single-domain particles suggest consistent directions of magnetization for a
large proportion of particles.
Received: 16 November 1998 / Accepted: 17 May 1999 相似文献