The Taklamakan Desert in China is one of the major source regions for Asian dust particles.All balloon-borne measurements in this report were carried out in Dunhuang,in the Taklamakan Desert,during calm weather condit...The Taklamakan Desert in China is one of the major source regions for Asian dust particles.All balloon-borne measurements in this report were carried out in Dunhuang,in the Taklamakan Desert,during calm weather conditions.The aerosol number concentration,size distribution,mass concentration,and horizontal mass flux due to westerly wind were investigated.The measurements were performed on 17 August 2001,17 October 2001,11 January 2002,and 30 April 2002.Five channels(0.3,0.5,0.8,1.2,and 3.6μm in diameter)were used in the Optical Particle Counter for particle measurements.The aerosol number concentration in the winter season(11 January 2002)at 3–5 km was very high.Variation of free-tropospheric aerosols on 30 April 2002 was noticeable.A super-micron range was noticeable in the size distribution of all the measurements.Many variations in temperature and aerosol concentration were found at these inversion points.High values of estimated mass concentration of aerosols were frequently observed in the atmosphere near the ground(i.e.,1–2 km);and interestingly,relatively high concentrations were frequently detected above 2 km from the surface.Wind patterns observed using ERA-Interim data at 500 and 850 hPa showed that westerly winds dominated in the Taklamakan Desert during the observation period.The average horizontal mass flux of background Asian dust due to westerly wind was observed to fall within the range of 58.5–1219 tons km?2 d?1.Vertical profiles of aerosol number concentrations showed that significant transport of aerosols dominated in the westerly region(i.e.,4–7 km).展开更多
Rotor time constant is an important parameter for the indirect lleld oraentateO control of mauc- tion motor. Incorrect rotor tittle constant value will cause the flux observer generating a wrong angu- lar orientation ...Rotor time constant is an important parameter for the indirect lleld oraentateO control of mauc- tion motor. Incorrect rotor tittle constant value will cause the flux observer generating a wrong angu- lar orientation of the rotor field. A new approach serves for rotor time constant on-line adaptation by setting the stator current to be zero for a short period. A smooth eorrector is designed to prevent ab- normal detection result from making adaptation. Impact of zero current duration on detection error and rotor speed is analyzed by experiments.展开更多
为了改善扩张状态观测器(ESO)的估计效果及解决自抗扰控制中b_0参数的整定问题,提出了一种基于N4SID(numerical algorithms for subspace state space system identification)的线性自抗扰控制策略.使用N4SID子空间辨识方法对系统模型...为了改善扩张状态观测器(ESO)的估计效果及解决自抗扰控制中b_0参数的整定问题,提出了一种基于N4SID(numerical algorithms for subspace state space system identification)的线性自抗扰控制策略.使用N4SID子空间辨识方法对系统模型的未知参数及线性自抗扰控制(LADRC)中的b_0参数进行辨识,减少被控系统的不确定因素,从而提高了扩张状态观测器对系统广义扰动的估计能力.仿真结果表明,该方法有效地改善了LADRC的控制效果,提高了扩张状态观测器的估计能力.展开更多
基金supported by the National Natural Science Foundations of China [grant numbers 41590871 and 41475136]the International Science&Technology Cooperation Program of China [grant number 2013DFG22820]
文摘The Taklamakan Desert in China is one of the major source regions for Asian dust particles.All balloon-borne measurements in this report were carried out in Dunhuang,in the Taklamakan Desert,during calm weather conditions.The aerosol number concentration,size distribution,mass concentration,and horizontal mass flux due to westerly wind were investigated.The measurements were performed on 17 August 2001,17 October 2001,11 January 2002,and 30 April 2002.Five channels(0.3,0.5,0.8,1.2,and 3.6μm in diameter)were used in the Optical Particle Counter for particle measurements.The aerosol number concentration in the winter season(11 January 2002)at 3–5 km was very high.Variation of free-tropospheric aerosols on 30 April 2002 was noticeable.A super-micron range was noticeable in the size distribution of all the measurements.Many variations in temperature and aerosol concentration were found at these inversion points.High values of estimated mass concentration of aerosols were frequently observed in the atmosphere near the ground(i.e.,1–2 km);and interestingly,relatively high concentrations were frequently detected above 2 km from the surface.Wind patterns observed using ERA-Interim data at 500 and 850 hPa showed that westerly winds dominated in the Taklamakan Desert during the observation period.The average horizontal mass flux of background Asian dust due to westerly wind was observed to fall within the range of 58.5–1219 tons km?2 d?1.Vertical profiles of aerosol number concentrations showed that significant transport of aerosols dominated in the westerly region(i.e.,4–7 km).
基金Supported by the National Natural Science Foundation of China(No.51276016)the Fundamental Research Funds for the Central University(No.FRF-TP-12-059A)
文摘Rotor time constant is an important parameter for the indirect lleld oraentateO control of mauc- tion motor. Incorrect rotor tittle constant value will cause the flux observer generating a wrong angu- lar orientation of the rotor field. A new approach serves for rotor time constant on-line adaptation by setting the stator current to be zero for a short period. A smooth eorrector is designed to prevent ab- normal detection result from making adaptation. Impact of zero current duration on detection error and rotor speed is analyzed by experiments.
文摘为了改善扩张状态观测器(ESO)的估计效果及解决自抗扰控制中b_0参数的整定问题,提出了一种基于N4SID(numerical algorithms for subspace state space system identification)的线性自抗扰控制策略.使用N4SID子空间辨识方法对系统模型的未知参数及线性自抗扰控制(LADRC)中的b_0参数进行辨识,减少被控系统的不确定因素,从而提高了扩张状态观测器对系统广义扰动的估计能力.仿真结果表明,该方法有效地改善了LADRC的控制效果,提高了扩张状态观测器的估计能力.
