Calculating palaeomagnetic poles for oceanic plates     

Richard G. Gordon  Allan Cox 《Geophysical Journal International》1980,63(3):619-640

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The information available for determining palaeopoles for oceanic plates includes data of four types: (1) palaeomagnetic measurements of inclinations but not declinations from core samples; (2) palaeopoles determined from magnetic anomalies over seamounts; (3) phase shifts of linear magnetic anomalies; and (4) palaeoequators determined from geological analysis of sediment cores. A method is presented which combines these different kinds of data and their respective confidence limits to yield a best fit pole, a confidence ellipse, estimates of the data importances and goodness of fit parameters. Using this method we calculate the Campanian pole position for the Pacific plate which is shown by a chi-squared test to be a reasonable fit to the data. We conclude that the method should be a useful tool for calculating pole paths for oceanic plates such as the Pacific and Indian plates.  相似文献   

A possible edge effect in enhanced network     

Harrison P. Jones  Douglas R. Brown 《Solar physics》1977,52(2):337-342

K-line observations of enhanced network taken with the NASA/SPO Multichannel Spectrometer on 28 September 1975 in support of OSO-8 are discussed. The data show a correlation between core brightness and asymmetry for spatial scans which cross enhanced network boundaries. The implications of this result concerning mass flow in and near supergranule boundaries are discussed.  相似文献   

A new map of crustal 'terranes' in the United States from COCORP deep seismic reflection profiling   总被引：3，自引：0，他引：3  

Larry D. Brown 《Geophysical Journal International》1991,105(1):3-13

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STRUCTURAL TENSION,MIGRATION, AND DEVELOPMENT: A CASE STUDY OF VENEZUELA*     

Victoria A. Lawson  Lawrence A. Brown 《The Professional geographer》1987,39(2):179-188

Mismatch of labor demand and supply, resulting from economic growth, is referred to here as structural tension. Spatial variations in structural tension are identified for Venezuelan states in 1971. Positive tension, indicating overutilization of human resources, prevails in urban areas. By contrast, rural locales exhibit underutilization due to rapid labor force growth without parallel increases in employment opportunities. Influence of structural tension, coupled with other migration determinants, upon destination choice by economically active immigrants is explored. Structural tension emerges as strongly significant for the total sample, displacing wages from the model. This is consistent with our contention that wages are a less precise indicator of labor supply and demand.  相似文献   

Coronal scattering as a source of flare-associated polarized hard X-rays     

Hudson  H.S.  Hurford  G.J.  Brown  J.C. 《Solar physics》2003,214(1):171-175

We consider the scattering of flare-associated X-rays above 1 keV at coronal heights, particularly from regions of enhanced density. This includes a discussion of the polarization of the scattered X-rays. Although the scattered radiation would not be bright by comparison with the total hard X-ray flux from a flare, its detectability would be enhanced for events located a few degrees behind the limb for which the dominant `footpoint' hard X-ray sources are occulted. Thus we predict that major flares occurring beyond the solar limb may be detectable via scattering in density enhancements that happen to be visible above the limb, and that such sources may be strongly polarized. Since thin-target bremsstrahlung will generally greatly exceed the scattered thick-target flux in flare loops themselves, these considerations apply only to coronal structures that do not contain significant populations of non-thermal electrons.  相似文献   

Seismic area zones: myth or reality?     

Gordon Woo 《地学学报》1994,6(5):535-536

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Flat rotation curves according to the fragmentation/shear flow model of galaxy formation     

Wilbur K. Brown 《Astrophysics and Space Science》1984,105(1):109-130

Initial conditions are derived from the fragmentation/shear flow model of galaxy formation and are used as input to the viscous action presumed to begin as soon as a galactic disk forms. A simple differential equation is found to describe the turbulent viscous evolution of a flat disk. Solutions to this equation produce rotation curves that closely resemble those observed in spiral and elliptical galaxies. For spirals, by using the mass distributions derived from the rotation curves and from Seiden's theory of star formation, exponential luminosity profiles are produced.Los Alamos National Laboratory is operated by the University of California for the United States Department of Energy under contract W-7405-ENG-36.  相似文献   

Sightings of Cetacea During Two Trans-Atlantic Yacht Races     

Brown  S. G.; Jones  S. J.; Boyde  A. 《ICES Journal of Marine Science》1971,34(1):106-120

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A model of the formation of spherical galaxies     

Wilbur K. Brown 《Astrophysics and Space Science》1980,72(1):15-31

Galactic mass distributions produced by the fragmentation model (in addition to those published previously) are examined. This is done by allowing the cubical fragment to assume any orientation in space. All distributions examined closely resemble observed galactic luminosity profiles, and, among the variety produced, was found the special logI versusr ^1/4 behavior of de Vaucouleurs' empirical law as well as the exponential behavior of spirals. Because of the apparent success of the model, the initial conditions and analytical methods are re-examined in detail.  相似文献   

Application of theE-ε turbulence closure model to separated atmospheric surface-layer flows     

G. E. Liston  R. L. Brown  J. Dent 《Boundary-Layer Meteorology》1993,66(3):281-301

Neutrally buoyant atmospheric surface-layer flow over a thin vertical wall has been studied using a turbulence closure scheme designed specifically to address flow problems containing high shears. The turbulent flow model consists of a general solution of the time averaged, steady state, twodimensional Navier-Stokes equations, where theE- turbulence model has been used to close the system of equations. Model output compares favorably with measurements made in both a full-scale field study and in an atmospheric wind tunnel. In the simulation of flow over a solid wall, two recirculation eddies are produced. The smallest eddy is located windward of the wall with a separation point located atx/h=–0.8, and the largest is located in the lee of the wall atx/h=5.8. Immediately downwind of the wall top, the turbulent kinetic energy, the energy dissipation rate, and the momentum flux all reach a local maximum. These peak values generally maintain their height positionz/h=1.0, but decrease progressively downwind. The turbulent viscosity is strongly modified under the influence of the wall, with a local maximum forming in the lee of the wall top, and a local minimum forming at a heightz/h=2.0 above the lee recirculation eddy. The surface momentum flux reduction due to the presence of the wall begins atx/h=–10.0. Minimum zero fluxes occur at the surface separation points, and a local peak in momentum flux is produced at the centers of each recirculation eddy. Downwind of the wall, the modeled surface flux reaches an equilibrium at roughlyx/h=30.0.  相似文献