The hominins of Shizilukou chose pebbles/cobbles from the nearby river shoal for flaking and tool making. The principal flaking technique is direct hard hammer percussion. Anvil- chipping and ...bi-polar technique were also used. Cores analysis shows a rather intense utilization rate, and no classic Levallois method was identified. Three operational chains could be identified in the tool production process: heavy-duty tools made on large-sized cobbles; reduction sequence that produced small flake blanks for light-duty tools; and the production of large flake blanks for heavy-duty tools. Light-duty tools like side scrapers, end scrapers, notches, points, awls and burins account for the
The Hanzhong Basin, located in the upper catchment of the Hanjiang River in the southern piedmont of the Qinling Mountains, central China. In the early 1980s, more than 10 Paleolithic open-air sites ...were identified from the basin. Those sites are distributed between the third to fifth terraces in the Hanjiang (Hanshui) River and its branches. The former analysis suggests that the lithic assemblage from the surface collection not only include cores, flakes, choppers, spheroids, scrapers, points, but also contain Acheulian-type tools such as hand-axes and picks. Some geologists put those site in the Middle Pleistocene based on the analysis of
Digital Servos with good performance and high accurate control via digital signal is the future development direction of robot. The form, the function and the principle of the digital servos are ...expatiated in the paper. System design section is composed of hardware design and software design. Each part of the hardware design complies with the modular design principles, every block is given in detail. And the software design mainly introduces data packet format of AX-12 and how to achieve half-duplex asynchronous serial communication between controller and AX-12. The application shows this digital servos controller can control AX-12, and it has been applied to obstacle avoidance for wheeled mobile robot.
New complete BV light curves of BL Eri are presented. Light-curve variability and asymmetry are seen in both B and V bands, and the observed times of light minimum indicate period changes. The light ...curves have been analyzed by using the light-curve-synthesis method. Our photometric solution reveals that BL Eri is a contact binary with a common convective envelope. An examination of the available photometric and spectroscopic data indicates that the light-curve variability may be due to changes of the component radii and the light-curve asymmetry may be consistent with starspot activity on one or both components.
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