Based on the Coupled Ocean-Atmospheric Response Experiment （COARE） bulk algorithm and the Naval Postgraduate School （NPS） model, a universal evaporation duct （UED） model that can flexibly accommodate the latest ...Based on the Coupled Ocean-Atmospheric Response Experiment （COARE） bulk algorithm and the Naval Postgraduate School （NPS） model, a universal evaporation duct （UED） model that can flexibly accommodate the latest improvements in component （such as stability function, velocity roughness, and scalar roughness） schemes for different stratification and wind conditions, is proposed in this paper. With the UED model, the sensitivity of the model-derived evaporation duct height （EDH） to stability function （ψ）, ocean wave effect under moderate to high wind speeds, and scalar roughness length parameterization, is investigated, and relative contributions of these factors are compared. The results show that the stability function is a key factor influencing the simulated EDH values. Under unstable conditions, the EDH values from stability functions of Fairall et al. （1996） and Hu and Zhang （1992） are generally higher than those from others; while under stable conditions, unreasonably high EDHs can be avoided by use of the stability functions of Hu and Zhang （1992） and Grachev et al. （2007）. Under moderate to high wind speeds, the increase in velocity roughness length z0 due to consideration of the true ocean wave effect acts to reduce modeled EDH values; this trend is more pronounced under stable conditions. Although the scalar roughness length parameterization has a minor effect on the model-derived EDH, a positive correlation is found between the scalar roughness length z0q and the model-derived EDH.展开更多
磁悬浮控制力矩陀螺(MSCMG,Magnetically Suspended Control MomentGyro)是大型航天器姿态控制的关键执行机构,影响MSCMG输出力矩准确度的一个关键因素是其框架伺服系统的控制精度.为提高MSCMG框架伺服系统的抗干扰能力和控制精度,提出...磁悬浮控制力矩陀螺(MSCMG,Magnetically Suspended Control MomentGyro)是大型航天器姿态控制的关键执行机构,影响MSCMG输出力矩准确度的一个关键因素是其框架伺服系统的控制精度.为提高MSCMG框架伺服系统的抗干扰能力和控制精度,提出了一种基于角加速度的干扰观测器.其设计思想是:卡尔曼滤波器利用角位置估计出角速度并送往状态观测器以获取准确的角加速度,角加速度和电流作为干扰观测器的输入以获得补偿电流,补偿电流加到电流环的输入端以补偿各种干扰.干扰观测器结构简单,抗干扰能力强.实验表明:该方法有效地提高了MSCMG框架伺服系统的角速度精度与稳定度.展开更多
基金Supported by the National Natural Science Foundation of China(41205004,41230421,and 41105065)China Meteorological Administration Special Public Welfare Research Fund(GYHY201106004)
文摘Based on the Coupled Ocean-Atmospheric Response Experiment （COARE） bulk algorithm and the Naval Postgraduate School （NPS） model, a universal evaporation duct （UED） model that can flexibly accommodate the latest improvements in component （such as stability function, velocity roughness, and scalar roughness） schemes for different stratification and wind conditions, is proposed in this paper. With the UED model, the sensitivity of the model-derived evaporation duct height （EDH） to stability function （ψ）, ocean wave effect under moderate to high wind speeds, and scalar roughness length parameterization, is investigated, and relative contributions of these factors are compared. The results show that the stability function is a key factor influencing the simulated EDH values. Under unstable conditions, the EDH values from stability functions of Fairall et al. （1996） and Hu and Zhang （1992） are generally higher than those from others; while under stable conditions, unreasonably high EDHs can be avoided by use of the stability functions of Hu and Zhang （1992） and Grachev et al. （2007）. Under moderate to high wind speeds, the increase in velocity roughness length z0 due to consideration of the true ocean wave effect acts to reduce modeled EDH values; this trend is more pronounced under stable conditions. Although the scalar roughness length parameterization has a minor effect on the model-derived EDH, a positive correlation is found between the scalar roughness length z0q and the model-derived EDH.
文摘磁悬浮控制力矩陀螺(MSCMG,Magnetically Suspended Control MomentGyro)是大型航天器姿态控制的关键执行机构,影响MSCMG输出力矩准确度的一个关键因素是其框架伺服系统的控制精度.为提高MSCMG框架伺服系统的抗干扰能力和控制精度,提出了一种基于角加速度的干扰观测器.其设计思想是:卡尔曼滤波器利用角位置估计出角速度并送往状态观测器以获取准确的角加速度,角加速度和电流作为干扰观测器的输入以获得补偿电流,补偿电流加到电流环的输入端以补偿各种干扰.干扰观测器结构简单,抗干扰能力强.实验表明:该方法有效地提高了MSCMG框架伺服系统的角速度精度与稳定度.
