On the basis of the gain-scheduled H∞ design strategy, a novel active fault-tolerant control scheme is proposed. Under the assumption that the effects of faults on the state-space matrices of systems can be of affine...On the basis of the gain-scheduled H∞ design strategy, a novel active fault-tolerant control scheme is proposed. Under the assumption that the effects of faults on the state-space matrices of systems can be of affine parameter dependence, a reconfigurable robust H∞ linear parameter varying controller is developed. The designed controller is a function of the fault effect factors that can be derived online by using a well-trained neural network. To demonstrate the effectiveness of the proposed method, a double inverted pendulum system, with a fault in the motor tachometer loop, is considered.展开更多
Based on the experimental results, in which the fabricated error of the double layer frequency selective surface (FSS) leads to the transmission loss and the resonant frequency leaves away the design resonant frequenc...Based on the experimental results, in which the fabricated error of the double layer frequency selective surface (FSS) leads to the transmission loss and the resonant frequency leaves away the design resonant frequency, the inter-layer separation distance (ISD) and the unit cell aligning error (UAE) were used as main variables to study the transmission performance attenuation of the double layer FSS configuration. The numerical analysis model for ISD and UAE was established and also was used to simulate the ring unit cell FSS transmission performance by the finite element and periodic moment methods. The double layer ring aperture FSS configuration designed was used as the numerical model. As a result of the numerical analysis, it is shown that both ISD and UAE produce insertion transmission loss (ITL) and insertion phase distortion (IPD) directly. Furthermore, ISD results in more loss of the amplitude of the transmitted signal for the FSS than UAE. It is significant for the designer of the multiplayer FSS to assign the fabricated error of the FSS dielectric layers. The UAE introduces the insertion phase variation badly.展开更多
This paper describes what is thought to be the first generation of a continuous wave deep ultraviolet laser at 275 nm by efficient frequency doubling of a blue-diode-pumped Pr:YLF laser at 550 nm.By employing a novel ...This paper describes what is thought to be the first generation of a continuous wave deep ultraviolet laser at 275 nm by efficient frequency doubling of a blue-diode-pumped Pr:YLF laser at 550 nm.By employing a novel fast-axis collimated blue semiconductor laser as the pump source,combined with a folded cavity and innovation coating technology,and utilizing a Brewster-cut BBO crystal for intracavity frequency doubling,TEM00 mode deep UV laser radiation at 275 nm with an output power of 351 mW is obtained.This marks the first report of achieving 275 nm laser generation based on Pr:LiYF4 to date.展开更多
随着风电大规模的并网,其所具有的“零惯量”特征使电网惯量水平降低,频率特性恶化。为寻求风电并网对系统惯量水平的影响规律,明晰系统运行边界,对风电并网系统的惯量特性及最小惯量需求展开研究评估。首先,在同步发电机不同运行方式下...随着风电大规模的并网,其所具有的“零惯量”特征使电网惯量水平降低,频率特性恶化。为寻求风电并网对系统惯量水平的影响规律,明晰系统运行边界,对风电并网系统的惯量特性及最小惯量需求展开研究评估。首先,在同步发电机不同运行方式下,基于理论推导出评估风电并网系统惯量特性变化的计算表达式,并分析系统惯量特性的变化规律。在风电附加虚拟惯量控制情况下,以惯量响应过程提供的能量为出发点,基于系统惯量削弱量和风电虚拟惯量的平均惯量支撑功率,定义了一项惯量变化系数COIC,以此来判定系统惯量水平变化情况。其次,建立考虑风电渗透率的改进系统频率响应模型(System frequency response,SFR),量化系统惯量与风电渗透率的关系,给出了风电并网系统最小惯量评估方法。最后,搭建了含风电接入的4机2区域模型,对理论分析结果和评估方法进行了仿真验证。展开更多
文摘On the basis of the gain-scheduled H∞ design strategy, a novel active fault-tolerant control scheme is proposed. Under the assumption that the effects of faults on the state-space matrices of systems can be of affine parameter dependence, a reconfigurable robust H∞ linear parameter varying controller is developed. The designed controller is a function of the fault effect factors that can be derived online by using a well-trained neural network. To demonstrate the effectiveness of the proposed method, a double inverted pendulum system, with a fault in the motor tachometer loop, is considered.
文摘Based on the experimental results, in which the fabricated error of the double layer frequency selective surface (FSS) leads to the transmission loss and the resonant frequency leaves away the design resonant frequency, the inter-layer separation distance (ISD) and the unit cell aligning error (UAE) were used as main variables to study the transmission performance attenuation of the double layer FSS configuration. The numerical analysis model for ISD and UAE was established and also was used to simulate the ring unit cell FSS transmission performance by the finite element and periodic moment methods. The double layer ring aperture FSS configuration designed was used as the numerical model. As a result of the numerical analysis, it is shown that both ISD and UAE produce insertion transmission loss (ITL) and insertion phase distortion (IPD) directly. Furthermore, ISD results in more loss of the amplitude of the transmitted signal for the FSS than UAE. It is significant for the designer of the multiplayer FSS to assign the fabricated error of the FSS dielectric layers. The UAE introduces the insertion phase variation badly.
文摘This paper describes what is thought to be the first generation of a continuous wave deep ultraviolet laser at 275 nm by efficient frequency doubling of a blue-diode-pumped Pr:YLF laser at 550 nm.By employing a novel fast-axis collimated blue semiconductor laser as the pump source,combined with a folded cavity and innovation coating technology,and utilizing a Brewster-cut BBO crystal for intracavity frequency doubling,TEM00 mode deep UV laser radiation at 275 nm with an output power of 351 mW is obtained.This marks the first report of achieving 275 nm laser generation based on Pr:LiYF4 to date.
文摘随着风电大规模的并网,其所具有的“零惯量”特征使电网惯量水平降低,频率特性恶化。为寻求风电并网对系统惯量水平的影响规律,明晰系统运行边界,对风电并网系统的惯量特性及最小惯量需求展开研究评估。首先,在同步发电机不同运行方式下,基于理论推导出评估风电并网系统惯量特性变化的计算表达式,并分析系统惯量特性的变化规律。在风电附加虚拟惯量控制情况下,以惯量响应过程提供的能量为出发点,基于系统惯量削弱量和风电虚拟惯量的平均惯量支撑功率,定义了一项惯量变化系数COIC,以此来判定系统惯量水平变化情况。其次,建立考虑风电渗透率的改进系统频率响应模型(System frequency response,SFR),量化系统惯量与风电渗透率的关系,给出了风电并网系统最小惯量评估方法。最后,搭建了含风电接入的4机2区域模型,对理论分析结果和评估方法进行了仿真验证。
