用φ185 mm管坯生产φ108~146 mm无缝钢管时,管坯单个质量小,换工具频繁,设备调整多,故障率高,限制了φ177 mm PQF连轧管机组的产能。研究了φ177 mm PQF连轧管机组的微张力定(减)径工艺,对其孔型、张力、各机架钢管壁厚、速度及力能参...用φ185 mm管坯生产φ108~146 mm无缝钢管时,管坯单个质量小,换工具频繁,设备调整多,故障率高,限制了φ177 mm PQF连轧管机组的产能。研究了φ177 mm PQF连轧管机组的微张力定(减)径工艺,对其孔型、张力、各机架钢管壁厚、速度及力能参数进行设计,并用数学解析方法在电子表格中将参数的计算编辑成程序。该方法具有简单、直观、易操作和易修改的特点。展开更多
Using impulse hypothesis to solve far-distance rendezvous is difficult to be realized in a real project and the guidance accuracy cannot be controlled. A two-maneuver guidance law is designed for the two-impulse rende...Using impulse hypothesis to solve far-distance rendezvous is difficult to be realized in a real project and the guidance accuracy cannot be controlled. A two-maneuver guidance law is designed for the two-impulse rendezvous problem. The velocity gain guidance is applied to the first maneuver and the time-cut-off law is applied to the second one. Theoretical and simulation results show that the plan is credible. Accuracy requirements in fardistance rendezvous and in transform to close-in rendezous can be met.展开更多
To investigate the feasibility and effectiveness of the designed control system used for driving and steering of an electric scooter, a model of differential steering was developed. The function of electronic differen...To investigate the feasibility and effectiveness of the designed control system used for driving and steering of an electric scooter, a model of differential steering was developed. The function of electronic differential steering was realized by controlling the speed of right or left wheel and the corresponding speed difference. The control system was simulated with MATLAB/SIMUL1NK and ADAMS. It is found that the motor load torque is proportional to the tire vertical force, so the adhesive capacity is met. The electric scooter can operate stably on the slope road at a speed of more than 1.5 m/s and turn stably at yawing velocities of 10° and 90°per second.展开更多
Taking cemented coal gangue pipeline transportation system in Suncun Coal Mine, Xinwen Mining Group, Shandong Province, China, as an example, the hydraulic calculation approaches and process about gravity pipeline tra...Taking cemented coal gangue pipeline transportation system in Suncun Coal Mine, Xinwen Mining Group, Shandong Province, China, as an example, the hydraulic calculation approaches and process about gravity pipeline transportation of backfill slurry were investigated. The results show that the backfill capability of the backfill system should be higher than 74.4 m3/h according to the mining production and backfill times in the mine; the minimum velocity (critical velocity) and practical working velocity of the backfill slurry are 1.44 and 3.82 m/s, respectively. Various formulae give the maximum ratio of total length to vertical height of pipeline (L/H ratio) of the backfill system of 5.4, and then the reliability and capability of the system can be evaluated.展开更多
The friction coefficients between the surfaces of a ball and a disc lubricated by a space lubricating oil No.4129 were measured at various operating conditions on a ball-disc friction test rig. Friction characteristic...The friction coefficients between the surfaces of a ball and a disc lubricated by a space lubricating oil No.4129 were measured at various operating conditions on a ball-disc friction test rig. Friction characteristic curves were obtained under sliding and rolling movements at point contact. A new model for calculation of the friction coefficient was presented. The results show that the bigger the load is, the larger the friction coefficient becomes. The rolling speed ranging from 1 m/s to10 m/s has an important effect on the friction coefficient. The friction coefficient increases with the increase in sliding speed and the decrease in rolling speed. The linear variation region of the friction coefficient versus the sliding speed at high rolling speed is wider than that at low rolling speed. The model for calculation of the friction coefficient is accurate for engineering use.展开更多
文摘用φ185 mm管坯生产φ108~146 mm无缝钢管时,管坯单个质量小,换工具频繁,设备调整多,故障率高,限制了φ177 mm PQF连轧管机组的产能。研究了φ177 mm PQF连轧管机组的微张力定(减)径工艺,对其孔型、张力、各机架钢管壁厚、速度及力能参数进行设计,并用数学解析方法在电子表格中将参数的计算编辑成程序。该方法具有简单、直观、易操作和易修改的特点。
文摘Using impulse hypothesis to solve far-distance rendezvous is difficult to be realized in a real project and the guidance accuracy cannot be controlled. A two-maneuver guidance law is designed for the two-impulse rendezvous problem. The velocity gain guidance is applied to the first maneuver and the time-cut-off law is applied to the second one. Theoretical and simulation results show that the plan is credible. Accuracy requirements in fardistance rendezvous and in transform to close-in rendezous can be met.
基金Supported by Scientific and Technological Project of Chongqing (CSTC2009AC6051)
文摘To investigate the feasibility and effectiveness of the designed control system used for driving and steering of an electric scooter, a model of differential steering was developed. The function of electronic differential steering was realized by controlling the speed of right or left wheel and the corresponding speed difference. The control system was simulated with MATLAB/SIMUL1NK and ADAMS. It is found that the motor load torque is proportional to the tire vertical force, so the adhesive capacity is met. The electric scooter can operate stably on the slope road at a speed of more than 1.5 m/s and turn stably at yawing velocities of 10° and 90°per second.
基金Project(50490270) supported by the National Natural Science Foundation of China
文摘Taking cemented coal gangue pipeline transportation system in Suncun Coal Mine, Xinwen Mining Group, Shandong Province, China, as an example, the hydraulic calculation approaches and process about gravity pipeline transportation of backfill slurry were investigated. The results show that the backfill capability of the backfill system should be higher than 74.4 m3/h according to the mining production and backfill times in the mine; the minimum velocity (critical velocity) and practical working velocity of the backfill slurry are 1.44 and 3.82 m/s, respectively. Various formulae give the maximum ratio of total length to vertical height of pipeline (L/H ratio) of the backfill system of 5.4, and then the reliability and capability of the system can be evaluated.
基金supported by the National Science Foundation of China (51105131)the Excellent Youth Foundation of Henan Scientific Committee (12410050002)the Creative Talent Foundation at Universities of Henan Province (2011HASTIT1016)
文摘The friction coefficients between the surfaces of a ball and a disc lubricated by a space lubricating oil No.4129 were measured at various operating conditions on a ball-disc friction test rig. Friction characteristic curves were obtained under sliding and rolling movements at point contact. A new model for calculation of the friction coefficient was presented. The results show that the bigger the load is, the larger the friction coefficient becomes. The rolling speed ranging from 1 m/s to10 m/s has an important effect on the friction coefficient. The friction coefficient increases with the increase in sliding speed and the decrease in rolling speed. The linear variation region of the friction coefficient versus the sliding speed at high rolling speed is wider than that at low rolling speed. The model for calculation of the friction coefficient is accurate for engineering use.
