利用Weaver海浪模型,对拖曳式Overhauser海洋磁场传感器海浪磁噪声与深度、波幅等之间的关系进行了理论分析,证明了在极端海况条件下对海浪磁噪声进行抑制的必要性.为提高海洋磁测灵敏度,提出了一种基于改进的Sage-Husa自适应Kalman算...利用Weaver海浪模型,对拖曳式Overhauser海洋磁场传感器海浪磁噪声与深度、波幅等之间的关系进行了理论分析,证明了在极端海况条件下对海浪磁噪声进行抑制的必要性.为提高海洋磁测灵敏度,提出了一种基于改进的Sage-Husa自适应Kalman算法的海浪磁场噪声抑制方法.仿真结果表明,该方法能在不需要先验的噪声统计或实时参考噪声的情况下,实现磁场噪声协方差的快速收敛;且与常规的Sage-Husa算法相比,改进后的Sage-Husa算法降低了对初始参数的依赖性.另外,设计了一种拖曳式Overhauser海洋磁场传感器测试仪来测试上述算法.对比结果表明该方法不仅实现了磁场噪声统计参数的自适应估计,而且比经典Kalman滤波具有更好的滤波效果;此外,海浪磁噪声的功率谱密度由50 p T/Hz1/2@1Hz下降到6 p T/Hz1/2@1Hz.展开更多
We report the first atomically resolved scanning tunneling microscope （STM） imaging in a water-cooled magnet （WM）, for which extremely harsh vibrations and noise have been the major challenge. This custom WM-STM f...We report the first atomically resolved scanning tunneling microscope （STM） imaging in a water-cooled magnet （WM）, for which extremely harsh vibrations and noise have been the major challenge. This custom WM-STM features an ultra-rigid and compact scan head in which the coarse approach is driven by our newly designed TunaDrive piezoelectric motor. A three-level spring hanging system is used for vibration isolation. Room-temperature raw-data images of graphite with quality atomic resolution were acquired in the presence of very strong magnetic fields, with a field strength up to 27 T, in a 32-mm-diameter bore WM with a maximum field strength of 27.5 T at a power rating of 10 MW, calibrated by nuclear magnetic resonance （NMR）. This record field strength of 27 T exceeds the maximal field strength achieved by the conventional supercon- ducting magnets. Besides, our WM-STM has paved the way to STM imaging using a 45 T, 32-mm-diameter bore hybrid magnet, which is the world＇s flagship magnet, producing the strongest steady magnetic field.展开更多
文摘利用Weaver海浪模型,对拖曳式Overhauser海洋磁场传感器海浪磁噪声与深度、波幅等之间的关系进行了理论分析,证明了在极端海况条件下对海浪磁噪声进行抑制的必要性.为提高海洋磁测灵敏度,提出了一种基于改进的Sage-Husa自适应Kalman算法的海浪磁场噪声抑制方法.仿真结果表明,该方法能在不需要先验的噪声统计或实时参考噪声的情况下,实现磁场噪声协方差的快速收敛;且与常规的Sage-Husa算法相比,改进后的Sage-Husa算法降低了对初始参数的依赖性.另外,设计了一种拖曳式Overhauser海洋磁场传感器测试仪来测试上述算法.对比结果表明该方法不仅实现了磁场噪声统计参数的自适应估计,而且比经典Kalman滤波具有更好的滤波效果;此外,海浪磁噪声的功率谱密度由50 p T/Hz1/2@1Hz下降到6 p T/Hz1/2@1Hz.
文摘We report the first atomically resolved scanning tunneling microscope （STM） imaging in a water-cooled magnet （WM）, for which extremely harsh vibrations and noise have been the major challenge. This custom WM-STM features an ultra-rigid and compact scan head in which the coarse approach is driven by our newly designed TunaDrive piezoelectric motor. A three-level spring hanging system is used for vibration isolation. Room-temperature raw-data images of graphite with quality atomic resolution were acquired in the presence of very strong magnetic fields, with a field strength up to 27 T, in a 32-mm-diameter bore WM with a maximum field strength of 27.5 T at a power rating of 10 MW, calibrated by nuclear magnetic resonance （NMR）. This record field strength of 27 T exceeds the maximal field strength achieved by the conventional supercon- ducting magnets. Besides, our WM-STM has paved the way to STM imaging using a 45 T, 32-mm-diameter bore hybrid magnet, which is the world＇s flagship magnet, producing the strongest steady magnetic field.
