The movement of sediment in estuary and on coast is directly restricted by the bed shear stress. Therefore, the research on the basic problem of sediment movement by the bed shear stress is an important way to researc...The movement of sediment in estuary and on coast is directly restricted by the bed shear stress. Therefore, the research on the basic problem of sediment movement by the bed shear stress is an important way to research the theory of sediment movement. However, there is not a measuring and computing method to measure the bed shear stress under a complicated dynamic effect like wave and current. This paper describes the measurement and test research on the bed shear stress in a long launder of direct current by the new instrument named thermal shearometer based on micro-nanotechnology. As shown by the research results, the thermal shearometer has a high response frequency and strong stability. The measured results can reflect the basic change of the bed shear stress under wave and wave-current effect, and confirm that the method of measuring bed shear stress under wave-current effect with thermal shearometer is feasible. Meanwhile, a preliminary method to compute the shear stress compounded by wave-current is put forward according to the tested and measured results, and then a reference for further study on the basic theory of sediment movement under a complicated dynamic effect is provided.展开更多
为提高全向智能轮椅床运动的平稳性和方向控制的准确性,研发了一种能护理失能老人的全向智能轮椅床。通过对移动平台进行力学和运动学分析,设计了一种精准的双闭环直流调速系统,实现了对全向智能轮椅床4个麦克纳姆轮转速的精确控制,解...为提高全向智能轮椅床运动的平稳性和方向控制的准确性,研发了一种能护理失能老人的全向智能轮椅床。通过对移动平台进行力学和运动学分析,设计了一种精准的双闭环直流调速系统,实现了对全向智能轮椅床4个麦克纳姆轮转速的精确控制,解决了全向智能轮椅床运动不稳定和方向控制偏离等问题。期望转速值确定后,通过对比经典比例积分微分(proportional integral differential, PID)算法和模糊PID算法的转速输出曲线,表明模糊PID算法更能满足全向智能轮椅床的使用要求。展开更多
基金financially supported by the National Natural Science Foundation of China(Grant No.51309158)funds from the National Key Scientific Instrument and Equipment Development Project(Grant No.2013YQ04091108)Important and Large Scientific and Technical Project of the Ministry of Communications(Grant No.201132874640)
文摘The movement of sediment in estuary and on coast is directly restricted by the bed shear stress. Therefore, the research on the basic problem of sediment movement by the bed shear stress is an important way to research the theory of sediment movement. However, there is not a measuring and computing method to measure the bed shear stress under a complicated dynamic effect like wave and current. This paper describes the measurement and test research on the bed shear stress in a long launder of direct current by the new instrument named thermal shearometer based on micro-nanotechnology. As shown by the research results, the thermal shearometer has a high response frequency and strong stability. The measured results can reflect the basic change of the bed shear stress under wave and wave-current effect, and confirm that the method of measuring bed shear stress under wave-current effect with thermal shearometer is feasible. Meanwhile, a preliminary method to compute the shear stress compounded by wave-current is put forward according to the tested and measured results, and then a reference for further study on the basic theory of sediment movement under a complicated dynamic effect is provided.
文摘为提高全向智能轮椅床运动的平稳性和方向控制的准确性,研发了一种能护理失能老人的全向智能轮椅床。通过对移动平台进行力学和运动学分析,设计了一种精准的双闭环直流调速系统,实现了对全向智能轮椅床4个麦克纳姆轮转速的精确控制,解决了全向智能轮椅床运动不稳定和方向控制偏离等问题。期望转速值确定后,通过对比经典比例积分微分(proportional integral differential, PID)算法和模糊PID算法的转速输出曲线,表明模糊PID算法更能满足全向智能轮椅床的使用要求。
