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31.
Calculations have been made to determine the effects of atmospheric drag and gravity on impact ejecta trajectories on Venus, Mars, and the Earth. The equations of motion were numerically integrated for a broad range of body sizes, initial velocities, and initial elevation angles. A dimensionless parameter was found from approximate analytic solutions which correlated the ejecta range, final impact angle, and final impact velocity for all three planets. 相似文献
32.
Donn S. Gorsline 《Geo-Marine Letters》1984,4(3-4):133-138
Fine-grained sediments comprise about 70% of all sediments and sedimentary rocks. In the past decade, research on these deposits has increasingly looked at processes and process-responses. While much of the earlier work was devoted to large-scale stratigraphic and petrologic studies, the present active frontiers appear to be in microstratigraphy, properties of grain aggregates and bulk characteristics, and the origins of these aggregates. Clays have historically been well studied, but silts are relatively poorly understood. Much of the geologic record must be reexamined. 相似文献
33.
Summary Infrasound has been recorded at long range from the launch and the re-entry of the first stage booster of Saturn V rockets. Detailed study has been made with the use of an acoustic ray-tracing procedure that involved actual temperature and wind data at the launch site and along the propagation path. Details of signal arrival times and duration are shown to be controlled by the nature of the ground-based sound channel, which in turn is determined by the atmospheric structure below about 60 km. Fluctuations in signal amplitudes are explained on the basis of interference of acoustic rays. 相似文献