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Medium-temperature baking of 1.3 GHz superconducting radio frequency single-cell cavity

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Radiation Detection Technology and Methods 2020年第4期4卷 507-512页

作者： Quan Zhou Fei-Si He Weimin Pan Peng Sha Zhenghui Mi baiqi liu Institute of High Energy Physics Chinese Academy of SciencesBeijing 100049China University of Chinese Academy of Sciences Beijing 100049China Key Laboratory of Particle Acceleration Physics and Technology Chinese Academy of SciencesBeijing 100049China Center for Superconducting RF and Cryogenics Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China

Background A reliable and repeatable post-processing technology of improving the performance of 1.3 GHz superconducting radio frequency(SRF)cavities is one of the critical technologies for the ILC and XFEL and ERL *** Three 1.3 GHz single-cell cavities were fabricated and received a baking in temperature 330℃,while the interior of the cavity stayed in ultra-high vacuum(UHV).The cavities were also vertical-tested after electropolishing(EP)with 120℃48-h baking and with nitrogen doping separately for a *** The Q_(0) of 1.3 GHz single cavity after medium-temperature baking can be 2-3×10^(10) in the accelerating gradient range of 2-35 MV/m in the 2 K vertical test in ***,the outer surface oxidation of niobium cavity caused by baking will decrease the performance of the SRF *** Medium-temperature(250-400℃)baking on the 1.3 GHz single-cell cavity will improve its Q_(0) in 2 K vertical test compared with EP followed by 120℃48-h baking baseline and reach a similar level of nitrogen doping,and the quench field will lower to a typical range of 20-30 MV/***,the cavity performance is sensitive to the baking time and temperature,which indicates that a tremendous improvement can be made on the current treatment.

关键词： Medium-temperature baking 1.3 GHz single-cell cavity Nitrogen doping

一种改进的IMU无定向动静混合高精度标定方法

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仪器仪表学报 2008年第6期29卷 1250-1254页

作者：刘百奇房建成北京航空航天大学仪器科学与光电工程学院北京100083

本文针对传统的IMU动静混合标定方法中IMU必须精确定向且实验过程复杂的问题,提出了一种改进的IMU无定向动静混合高精度标定方法,该方法仅需测试设备提供水平基准,通过6个位置的十二次旋转实验,即可标定出陀螺标度因数、常值漂移、安装... 详细信息

本文针对传统的IMU动静混合标定方法中IMU必须精确定向且实验过程复杂的问题,提出了一种改进的IMU无定向动静混合高精度标定方法,该方法仅需测试设备提供水平基准,通过6个位置的十二次旋转实验,即可标定出陀螺标度因数、常值漂移、安装误差、与g有关项和加速度计标度因数、常值偏置、安装误差等全部33个误差系数。实验结果表明,该方法与传统的动静混合高精度标定方法准确度相当,但标定的过程得到了简化,标定效率也得到了大大的提高。

关键词：捷联惯性导航系统 IMU 标定无定向动静混合

一种基于可观测度分析的SINS/GPS自适应反馈校正滤波新方法

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航空学报 2008年第2期29卷 430-436页

作者：刘百奇房建成北京航空航天大学仪器科学与光电工程学院北京100083

针对机载捷联惯导系统(SINS)/全球定位系统(GPS)组合导航系统不完全可观测导致滤波器精度下降甚至发散的问题,提出了一种基于系统状态可观测度分析的自适应反馈校正滤波新方法。该滤波方法改进了系统可观测度的归一化处理方法,将归一化... 详细信息

针对机载捷联惯导系统(SINS)/全球定位系统(GPS)组合导航系统不完全可观测导致滤波器精度下降甚至发散的问题,提出了一种基于系统状态可观测度分析的自适应反馈校正滤波新方法。该滤波方法改进了系统可观测度的归一化处理方法,将归一化处理后的系统状态可观测度作为反馈因子,对SINS系统进行自适应反馈校正。最后,将该方法应用于机载合成孔径雷达(SAR)运动补偿用SINS/GPS组合导航系统中,飞行试验结果表明该方法在系统不完全可观测的情况下有效地提高了导航精度。

关键词：组合导航卡尔曼滤波自适应反馈校正 SINS/GPS 可观测度

Meteor radar observation of circulation near mesopause over Wuhan

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Chinese Science Bulletin 2003年第15期48卷 1634-1638页

作者： XIONG Jiangang, WAN Weixin, NING baiqi & liu Libo Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China Correspondence should be addressed to Xiong Jiangang (e-mail: xjg@***) Wuhan Institute of Physics and Mathematics Chinese Academy of Sciences Wuhan China

The Wuhan meteor radar is the first all-sky meteor radar in China. The circulation near the mesopause from February to September 2002 is studied based on the data obtained by the Wuhan meteor radar. The zonal wind is usually eastward in winter from 80 to 100 km. The mean zonal wind become westward from March to early of May, when the winter circulation reverses to the summer circulation. But at the meteor heights, the zonal circulation usually becomes eastward after the middle of May. The meridional circulation is always equatorward. The peaks of the meridional wind move downward with the height, and the peak value reaches its maximum of 21 ms-1 in July. Having made a comparison between monthly mean wind and HWM93 model wind, the value of southward wind, the maximal value of eastward wind as well as the reversal height of zonal wind are found to be quite different from each other.

关键词：武汉市气象雷达带状气流数据采集中间层顶

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一种改进的高精度POS时间同步方法

仪器仪表学报 2011年第10期32卷 2198-2204页

作者：刘占超房建成刘百奇北京航空航天大学仪器科学与光电工程学院北京100191

结合现有时间同步方法及高精度POS的应用需求,提出了一种以GPS接收机输出的1PPS秒脉冲为基准,采用数字参数反馈方式,对惯性测量单元的数据采集脉冲周期进行实时修正的高精度POS时间同步方法,并给出了一种简易的POS时间同步精度测试方法... 详细信息

结合现有时间同步方法及高精度POS的应用需求,提出了一种以GPS接收机输出的1PPS秒脉冲为基准,采用数字参数反馈方式,对惯性测量单元的数据采集脉冲周期进行实时修正的高精度POS时间同步方法,并给出了一种简易的POS时间同步精度测试方法。然后结合光纤陀螺POS实际系统进行了时间同步精度测试和对比实验。结果表明,所提出的时间同步方法能够克服时钟漂移并修正时间信号传输延迟,在保证工作可靠性的同时实现了在融合点上数据的高精度同步。

关键词：位置和姿态测量系统秒脉冲时间同步时钟漂移

A study of the ionogram derived effective scale height around the ionospheric hmF2

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A study of the ionogram derived effective scale height aroun...

一种激光断面仪运动补偿用IMU/GPS/OD系统

中国科学院地质与地球物理研究所2006学术年会

作者： Libo liu,Weixing Wan,and baiqi Ning Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China

The diurnal,seasonal,and solar activity variations of the ionogram derived scale height around the ionospheric F layer peak(Hm) are statistically analyzed at Wuhan(114.4°E, 30.6°N) and the yearly variations of Hm are also investigated for Wuhan and other 12 stations where Hm data is ***,as a measure of the slope of the topside electron number density profiles,is calculated from the bottomside electron density profiles derived from vertical sounding ionograms using the UMLCAR *** indicate that the value of median Hm increases with increasing solar *** is highest in summer and lowest in winter during the daytime,while it exhibits a much smaller seasonal variation at night.A common feature presented at these 13 stations is that,Hm undergoes a yearly annual variation with a maximum in summer during the *** annual variation becomes much weak or disappears from late night to *** addition,a moderate positive correlation is found between Hm with hmF2 and a strong correlation between the bottomside thickness parameter B0 and *** later provides a new and convenient way for empirical modeling the topside ionospheric shape only from the established B0 parameter set.

关键词： ionosphere scale height electron profile annual variation

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仪器仪表学报 2012年第3期33卷 677-682页

作者：刘百奇康泰钟李建利北京航空航天大学仪器科学与光电工程学院北京100191

针对车载激光路面断面仪性能受检测车垂直振动及姿态变化影响的问题,设计并实现了一种车载激光断面仪运动补偿用IMU/GPS/OD组合测量系统,采用低成本IMU结合捷联解算算法计算检测车的三维位置、速度和姿态,通过GPS和里程仪结合最优滤波... 详细信息

针对车载激光路面断面仪性能受检测车垂直振动及姿态变化影响的问题,设计并实现了一种车载激光断面仪运动补偿用IMU/GPS/OD组合测量系统,采用低成本IMU结合捷联解算算法计算检测车的三维位置、速度和姿态,通过GPS和里程仪结合最优滤波技术抑制低成本IMU在捷联解算过程中形成的累积误差,并提出了一种基于IMU/GPS/OD组合测量系统的检测车垂直振动位移的计算方法。最后进行了室内实验验证,实验结果表明,该IMU/GPS/OD组合测量系统应用于车载激光断面仪是可行的。

关键词： IMU/GPS/OD 运动补偿垂直振动位移激光断面仪道路断面

Statistical modeling of ionospheric foF2 over Wuhan

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Statistical modeling of ionospheric foF2 over Wuhan

中国科学院地质与地球物理研究所2004学术年会

作者： Libo liu,Weixing Wan,and baiqi Ning Institute of Geology and Geophysics.Chinese Academy of Sciences,Beijing.China

[1]Half-hourly values of the critical frequency of the ionospheric F region,foF2, obtained at Wuhan Ionospheric Observatory(geographic 114.4°E,30.6°N;45.2°dip), China,during the period fiom 195 7 to 1991 have been used to investigate the solar activity dependence of the monthly median foF2,and to construct single-station models ushing Fourier expansion and cubic-B splines *** climatological models incorporate local standard time,month,and solar cycle variations of *** analyses show that,over Wuhan,the monthly median foF2 has a significantly nonlinear dependence on the current and historical solar *** the monthly median F107 in the prior month can significantly improve the accuracy of our *** the complex influence of solar activities is approximately expressed by a general nonlinear function. Our models are in good agreement with observations,with standard deviations between about 0.26 to 0.58 *** contrast,the IRI model tends to overestimate foF2 over Wuhan and has a lower accuracy with standard deviations between about 0.5 to 1 *** TERMS:2447 Ionosphere:Modeling and forecasting;2479 Ionosphere:Solar radiation and cosmic ray effects;6929 Radio Science:Ionospheric physics(2409);KEYWORDS:ionospheric foF2,F107, solar cycle variation,monthly median model

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大视场星光修正惯性导航半实物仿真系统设计

航天控制 2018年第2期36卷 70-76,82页

作者：刘百奇刘建设吕艳中国运载火箭技术研究院研究发展中心北京100076 空间物理重点实验室北京100076

针对飞行实验成本高、难度大的问题,设计并实现了一种大视场星光修正惯性导航系统的半实物仿真试验系统。该系统采用轨迹发生器模拟生成飞行过程中导航传感器数据,利用真实星敏感器与IMU的静态输出获得器件误差,结合时间软同步完成信息... 详细信息

针对飞行实验成本高、难度大的问题,设计并实现了一种大视场星光修正惯性导航系统的半实物仿真试验系统。该系统采用轨迹发生器模拟生成飞行过程中导航传感器数据,利用真实星敏感器与IMU的静态输出获得器件误差,结合时间软同步完成信息采集,通过组合导航模块实现模拟飞行过程的组合导航解算。实验结果表明,该系统具有较强的灵活性和通用性,可在地面验证星光修正惯性导航算法性能,具有一定的工程应用价值。

关键词：星光修正捷联惯导半实物仿真大视场敏感器