The pavement layered structures are composed of surface layer,road base and multi-layered soil foundation.They can be undermined over time by repeated vehicle loads.In this study,a hybrid numerical method which can ev...The pavement layered structures are composed of surface layer,road base and multi-layered soil foundation.They can be undermined over time by repeated vehicle loads.In this study,a hybrid numerical method which can evaluate the displacement responses of pavement structures under dynamic falling weight deflectometer(FWD)loads.The proposed method consists of two parts:(a)the dynamic stiffness matrices of the points at the surface in the frequency domain which is based on the domain-transformation and dual vector form equation,and(b)interpolates the dynamic stiffness matrices by a continues rational function of frequency.The mixed variables formulation(MVF)can treat multiple degree of freedom systems with considering the coupling term between degree of freedoms.The accuracy of the developed method has been demonstrated by comparison between the proposed method and published results from the other method.Then the proposed method can be applied as a forward calculation technique to emulate the falling weight deflectometer test for multi-layered pavement structures.展开更多
常规Duffing振子检测方法只能确定待测弱信号的有无及幅值大小,却无法给出其在时域上的分布信息,且待测信号包络有起伏时会引起Duffing振子系统的误判。针对上述问题,本文提出可变幅值系数的短时Duffing振子阵列检测方法。应用互模糊函...常规Duffing振子检测方法只能确定待测弱信号的有无及幅值大小,却无法给出其在时域上的分布信息,且待测信号包络有起伏时会引起Duffing振子系统的误判。针对上述问题,本文提出可变幅值系数的短时Duffing振子阵列检测方法。应用互模糊函数推导出随机振幅包络起伏信号通过短时处理可以降低包络起伏因素对Duffing振子检测性能的影响,对信号加时间窗的短时处理可以保证窗内信号近似平稳,并可同时获得待测信号在时域上的分布信息。为克服相图判别法定性分析的不足,降低待测信号与内置策动力合成的总策动力幅值小于跃变阈值时出现的漏报误判概率,提出可变幅值系数的Poincare映射集判别方法,给出了量化统计判别结果。仿真及实测水声信号检测结果表明,在-33 d B的低信噪比背景下仍可实现信号的检测判别。展开更多
无刷直流电机(brushless direct current motor,BLDCM)是一种非线性的系统,传统比例积分(proportional-integral,PI)控制存在响应速度慢、动态性能差等问题。针对无刷直流电机运行过程的精准控制存在系统不确定性问题,通过将时变论域、...无刷直流电机(brushless direct current motor,BLDCM)是一种非线性的系统,传统比例积分(proportional-integral,PI)控制存在响应速度慢、动态性能差等问题。针对无刷直流电机运行过程的精准控制存在系统不确定性问题,通过将时变论域、变积分逻辑、区间二型模糊集合综合判断与模糊比例积分微分(proportional-integral-derivative,PID)控制规则相结合,提出了一种新型的二型模糊变积分PID控制器,解决了传统PI控制与一型模糊控制的转速跟踪不足、容易偏离目标转速等问题。仿真结果表明,将二型模糊变积分PID控制算法应用在双闭环调速系统中,获得了更快的转速响应速度、更强的鲁棒性以及更小的超调量,所提方法为无刷直流电机系统提供了新的控制思路。展开更多
基金The authors are grateful for the financial support of the National Key Research and Development Program of China(No.2016YFC0802400)the National Natural Science Foundation of China under Grant No.(51508203,51678536,41404096)+2 种基金the Outstanding Young Talent Research Fund of Zhengzhou University(1621323001)Program for Innovative Research Team(in Science and Technology)in University of Henan Province(18IRTSTHN007)the Program for Science and Technology Innovation Talents in Universities of Henan Province(Grant No.19HASTIT043),and the authors extend their sincere gratitude.
文摘The pavement layered structures are composed of surface layer,road base and multi-layered soil foundation.They can be undermined over time by repeated vehicle loads.In this study,a hybrid numerical method which can evaluate the displacement responses of pavement structures under dynamic falling weight deflectometer(FWD)loads.The proposed method consists of two parts:(a)the dynamic stiffness matrices of the points at the surface in the frequency domain which is based on the domain-transformation and dual vector form equation,and(b)interpolates the dynamic stiffness matrices by a continues rational function of frequency.The mixed variables formulation(MVF)can treat multiple degree of freedom systems with considering the coupling term between degree of freedoms.The accuracy of the developed method has been demonstrated by comparison between the proposed method and published results from the other method.Then the proposed method can be applied as a forward calculation technique to emulate the falling weight deflectometer test for multi-layered pavement structures.
文摘常规Duffing振子检测方法只能确定待测弱信号的有无及幅值大小,却无法给出其在时域上的分布信息,且待测信号包络有起伏时会引起Duffing振子系统的误判。针对上述问题,本文提出可变幅值系数的短时Duffing振子阵列检测方法。应用互模糊函数推导出随机振幅包络起伏信号通过短时处理可以降低包络起伏因素对Duffing振子检测性能的影响,对信号加时间窗的短时处理可以保证窗内信号近似平稳,并可同时获得待测信号在时域上的分布信息。为克服相图判别法定性分析的不足,降低待测信号与内置策动力合成的总策动力幅值小于跃变阈值时出现的漏报误判概率,提出可变幅值系数的Poincare映射集判别方法,给出了量化统计判别结果。仿真及实测水声信号检测结果表明,在-33 d B的低信噪比背景下仍可实现信号的检测判别。
文摘无刷直流电机(brushless direct current motor,BLDCM)是一种非线性的系统,传统比例积分(proportional-integral,PI)控制存在响应速度慢、动态性能差等问题。针对无刷直流电机运行过程的精准控制存在系统不确定性问题,通过将时变论域、变积分逻辑、区间二型模糊集合综合判断与模糊比例积分微分(proportional-integral-derivative,PID)控制规则相结合,提出了一种新型的二型模糊变积分PID控制器,解决了传统PI控制与一型模糊控制的转速跟踪不足、容易偏离目标转速等问题。仿真结果表明,将二型模糊变积分PID控制算法应用在双闭环调速系统中,获得了更快的转速响应速度、更强的鲁棒性以及更小的超调量,所提方法为无刷直流电机系统提供了新的控制思路。
