介绍了轨道型被动NES(Nonlinear Energy Sink),并对附加NES装置的5层钢框架进行了白噪声激励下的振动台实验,结果表明了NES能在多个频率范围内抑制结构振动。基于NES的这种优点,将其应用到高层结构的风振控制上。采用线性回归方法的AR模...介绍了轨道型被动NES(Nonlinear Energy Sink),并对附加NES装置的5层钢框架进行了白噪声激励下的振动台实验,结果表明了NES能在多个频率范围内抑制结构振动。基于NES的这种优点,将其应用到高层结构的风振控制上。采用线性回归方法的AR模型,模拟了不同高度处的脉动风速时程作为建筑结构的外部激励。以脉动风激励下高层建筑顶层的加速度为控制目标,对NES的质量、轨道表达式和黏滞阻尼参数进行了一系列优化,选择较优的参数对NES控制下某结构的脉动风致振动进行了仿真计算。计算结果表明:NES可以有效减小脉动风作用下建筑结构的最大加速度与加速度均方根,并且其可以同时减小结构多个模态的振动,从而提高风载荷下高层建筑的舒适度。展开更多
In this paper,E-H mode transition in magnetic-pole-enhanced inductively coupled neon-argon mixture plasma is investigated in terms of fundamental plasma parameters as a function of argon fraction(0%-100%),operating pr...In this paper,E-H mode transition in magnetic-pole-enhanced inductively coupled neon-argon mixture plasma is investigated in terms of fundamental plasma parameters as a function of argon fraction(0%-100%),operating pressure(1 Pa,5 Pa,10 Pa and 50 Pa),and radio frequency(RF)power(5-100 W).An RF compensated Langmuir probe and optical emission spectroscopy are used for the diagnostics of the plasma under study.Owing to the lower ionization potential and higher collision cross-section of argon,when its fraction in the discharge is increased,the mode transition occurs at lower RF power;i.e.for 0%argon and1 Pa pressure,the threshold power of the E-H mode transition is 65 W,which reduces to 20 W when the argon fraction is increased.The electron density increases with the argon fraction at afixed pressure,whereas the temperature decreases with the argon fraction.The relaxation length of the low-energy electrons increases,and decreases for high-energy electrons with argon fraction,due to the Ramseur effect.However,the relaxation length of both groups of electrons decreases with pressure due to reduction in the mean free path.The electron energy probability function(EEPF)profiles are non-Maxwellian in E-mode,attributable to the nonlocal electron kinetics in this mode;however,they evolve to Maxwellian distribution when the discharge transforms to H-mode due to lower electron temperature and higher electron density in H-mode.The tail of the measured EEPFs is found to deplete in both E-and H-modes when the argon fraction in the discharge is increased,because argon has a much lower excitation potential(11.5 eV)than neon(16.6 eV).展开更多
文摘介绍了轨道型被动NES(Nonlinear Energy Sink),并对附加NES装置的5层钢框架进行了白噪声激励下的振动台实验,结果表明了NES能在多个频率范围内抑制结构振动。基于NES的这种优点,将其应用到高层结构的风振控制上。采用线性回归方法的AR模型,模拟了不同高度处的脉动风速时程作为建筑结构的外部激励。以脉动风激励下高层建筑顶层的加速度为控制目标,对NES的质量、轨道表达式和黏滞阻尼参数进行了一系列优化,选择较优的参数对NES控制下某结构的脉动风致振动进行了仿真计算。计算结果表明:NES可以有效减小脉动风作用下建筑结构的最大加速度与加速度均方根,并且其可以同时减小结构多个模态的振动,从而提高风载荷下高层建筑的舒适度。
基金partially supported by Quaid-i-Azam University URF for the year 2019-2020Higher Education Commission(HEC)P.No.820 for Plasma Physics Gomal University(D I Khan)。
文摘In this paper,E-H mode transition in magnetic-pole-enhanced inductively coupled neon-argon mixture plasma is investigated in terms of fundamental plasma parameters as a function of argon fraction(0%-100%),operating pressure(1 Pa,5 Pa,10 Pa and 50 Pa),and radio frequency(RF)power(5-100 W).An RF compensated Langmuir probe and optical emission spectroscopy are used for the diagnostics of the plasma under study.Owing to the lower ionization potential and higher collision cross-section of argon,when its fraction in the discharge is increased,the mode transition occurs at lower RF power;i.e.for 0%argon and1 Pa pressure,the threshold power of the E-H mode transition is 65 W,which reduces to 20 W when the argon fraction is increased.The electron density increases with the argon fraction at afixed pressure,whereas the temperature decreases with the argon fraction.The relaxation length of the low-energy electrons increases,and decreases for high-energy electrons with argon fraction,due to the Ramseur effect.However,the relaxation length of both groups of electrons decreases with pressure due to reduction in the mean free path.The electron energy probability function(EEPF)profiles are non-Maxwellian in E-mode,attributable to the nonlocal electron kinetics in this mode;however,they evolve to Maxwellian distribution when the discharge transforms to H-mode due to lower electron temperature and higher electron density in H-mode.The tail of the measured EEPFs is found to deplete in both E-and H-modes when the argon fraction in the discharge is increased,because argon has a much lower excitation potential(11.5 eV)than neon(16.6 eV).
