A flexible connector of lifting pipes in a deep sea mining system is designed. The buttress thread （ based on API standard） is used and foreign experience in connector design is referred to. With this kind of connec...A flexible connector of lifting pipes in a deep sea mining system is designed. The buttress thread （ based on API standard） is used and foreign experience in connector design is referred to. With this kind of connector, the lifting pipe wiU only bear the axial force, free of moment. The strength of the connector is analyzed in detail, including the connecting strength of the buttress thread, the dynamic load of the pipe system, pressures inside and outside of the pipe, the lateral stress of the pipe wall and so on. Especially, a geometric model is built for 3-D contact stress analysis. The distribution graph of contact stress is presented. It is indicated that the strength of the spherical connector meets the demand.展开更多
Lift-off velocity of saltating sand particles in wind-blown sand located at 1.0 mm above the sand bed surface was measured using a phase Doppler particle analyzer in a wind tunnel. The results show that the probabilit...Lift-off velocity of saltating sand particles in wind-blown sand located at 1.0 mm above the sand bed surface was measured using a phase Doppler particle analyzer in a wind tunnel. The results show that the probability distribution of lift-off velocity can be expressed as a lognormal function, while that of lift-off angle follows an exponential function. The probability distribution of lift-off angle conditioned for each lift-off velocity also follows an exponential function, with a slope that becomes steeper with increasing lift-off velocity. This implies that the probability distribution of lift-off velocity is strongly dependent on the lift-off angle. However, these lift-off parameters are generally treated as an independent joint probability distribution in the literature. Numerical simulations were carried out to investigate the effects of conditional versus independent joint probability distributions on the vertical sand mass flux distribution. The simulation results derived from the conditional joint probability distribution agree much better with experimental data than those from the independent ones. Thus, it is better to describe the lift-off velocity of saltating sand particles using the conditional joint probability distribution. These results improve our understanding of saltation processes in wind-blown sand.展开更多
为适应船舶摇摆时的偏载工况,实现自动化管子处理作业需求,研制了船用一体化游车大钩。该游车大钩额定载荷达到5850 k N,主要由游车大钩本体、吊环倾斜机构、钩体旋转锁紧机构、滑车总成、双导轨总成、液压电控系统等组成,配置的旋转关...为适应船舶摇摆时的偏载工况,实现自动化管子处理作业需求,研制了船用一体化游车大钩。该游车大钩额定载荷达到5850 k N,主要由游车大钩本体、吊环倾斜机构、钩体旋转锁紧机构、滑车总成、双导轨总成、液压电控系统等组成,配置的旋转关节和钩体旋转锁紧机构可自适应船舶横摇和纵摇工况,吊环倾斜机构配合动力猫道和铁钻工实现自动化管子处理作业。经游钩本体的型式试验、联调试验和海上作业验证,该游车大钩自动化程度高,运行可靠,满足船舶自动化管子处理作业要求。展开更多
基金This research was financially supported by China Ocean Mineral Resources R &D Association (Grant No. DY105-03-02-17) .
文摘A flexible connector of lifting pipes in a deep sea mining system is designed. The buttress thread （ based on API standard） is used and foreign experience in connector design is referred to. With this kind of connector, the lifting pipe wiU only bear the axial force, free of moment. The strength of the connector is analyzed in detail, including the connecting strength of the buttress thread, the dynamic load of the pipe system, pressures inside and outside of the pipe, the lateral stress of the pipe wall and so on. Especially, a geometric model is built for 3-D contact stress analysis. The distribution graph of contact stress is presented. It is indicated that the strength of the spherical connector meets the demand.
基金supported by the Fundamental Research Funds for the Central Universities of China(GK201503053)the National Natural Science Foundation of China(41601002)
文摘Lift-off velocity of saltating sand particles in wind-blown sand located at 1.0 mm above the sand bed surface was measured using a phase Doppler particle analyzer in a wind tunnel. The results show that the probability distribution of lift-off velocity can be expressed as a lognormal function, while that of lift-off angle follows an exponential function. The probability distribution of lift-off angle conditioned for each lift-off velocity also follows an exponential function, with a slope that becomes steeper with increasing lift-off velocity. This implies that the probability distribution of lift-off velocity is strongly dependent on the lift-off angle. However, these lift-off parameters are generally treated as an independent joint probability distribution in the literature. Numerical simulations were carried out to investigate the effects of conditional versus independent joint probability distributions on the vertical sand mass flux distribution. The simulation results derived from the conditional joint probability distribution agree much better with experimental data than those from the independent ones. Thus, it is better to describe the lift-off velocity of saltating sand particles using the conditional joint probability distribution. These results improve our understanding of saltation processes in wind-blown sand.
文摘为适应船舶摇摆时的偏载工况,实现自动化管子处理作业需求,研制了船用一体化游车大钩。该游车大钩额定载荷达到5850 k N,主要由游车大钩本体、吊环倾斜机构、钩体旋转锁紧机构、滑车总成、双导轨总成、液压电控系统等组成,配置的旋转关节和钩体旋转锁紧机构可自适应船舶横摇和纵摇工况,吊环倾斜机构配合动力猫道和铁钻工实现自动化管子处理作业。经游钩本体的型式试验、联调试验和海上作业验证,该游车大钩自动化程度高,运行可靠,满足船舶自动化管子处理作业要求。
