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791.
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Raymond J. Talbot Jr. 《Astrophysics and Space Science》1973,20(1):241-249
The enhanced -decay rate of ionized187Re in stars has been studied within the context of a detailed numerical model of the production ofr-process elements and their recycling through stars during the course of galactic evolution. It is concluded that the enhanced decay rate does not significantly reduce the Re-Os chronometer age for the Galaxy. Consequently, the187Re -decay half-life and the neutron cross-section ratio (186Os)/(187Os) remain as the significant uncertainties in this chronology. Unlike the uncertainties in other chronologies, both are amenable to laboratory measurements. 相似文献
793.
John P. Hagen Paul N. Swanson Robert W. Haas Fred L. Wefer Raymond W. Vogt 《Solar physics》1971,21(2):286-296
The 7 March, 1970 total solar eclipse was observed at wavelengths of 3.2 and 8.3 mm; the object being to use the knife edge of the Moon as it passed across the Sun to improve angular resolution on the Sun. This in turn would provide a radial brightness distribution of the Sun with an angular resolution of a few seconds of arc.Excellent eclipse curves were obtained at 3 mm; however, some external interference marred the 8 mm record near totality.The 8 mm brightness distribution is subject to some uncertainty, but tends to show limb brightening. The 3 mm brightness distribution shows a well defined complex limb brightening within about 1 arc min of the optical limb. The maximum brightening is approximately 30% above the average disc temperature. 相似文献
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A numerical technique called Summary Representation was used to solve the problem of seepage through a leaky sheetpile; this particular method was selected owing to its accuracy and computational speed. Seepage parameters were evaluated quantitatively and the influence of the leakiness of sheetpiles in a porous medium underlain by an impervious horizontal stratum was determined. The case of a single sheetpile was first considered, and the effect of the depth of penetration and coefficient of leakiness on the total rate of flow and on the values of the exit gradient was analysed. Next, the flow under an impervious dam was considered to assess the accuracy of the method. Finally, the case of seepage under a dam with leaky sheetpiles at both ends was studied, including the effect of the leaky sheetpiles on the uplift pressure acting along the foundation of the dam. Patterns of seepage through the flow line deformation that is caused by the leakiness of the sheetpiles. 相似文献
800.
Raymond Hide 《Pure and Applied Geophysics》1983,121(3):365-374
An outline is given of some recent and current research in the Geophysical Fluid Dynamics Laboratory of the UK Meteorological Office, on the dynamics of rotating fluids and planetary atmospheres. Many of these investigations bear on the problem of creating a theoretical framework for atmospheric predictability studies. 相似文献