延迟是全球卫星导航定位中重要的误差源之一,提高电离层TEC建模和预报精度对改善卫星导航定位精度至关重要.本文构建了以太阳辐射通量指数F_(10.7)、地磁活动指数Dst、地理坐标和中国科学院(Chinese Academy of Sciences,CAS)GIM数据为...延迟是全球卫星导航定位中重要的误差源之一,提高电离层TEC建模和预报精度对改善卫星导航定位精度至关重要.本文构建了以太阳辐射通量指数F_(10.7)、地磁活动指数Dst、地理坐标和中国科学院(Chinese Academy of Sciences,CAS)GIM数据为输入参数的NeuralProphet神经网络模型(NP模型),实现在2015年3月特大磁暴期中国区域电离层TEC短期预报.为验证NP模型的预报精度,本文同时构建了长短期记忆神经网络(Long Short-term Memory Neural Network,LSTM)模型进行对比分析.结果统计分析表明,NP模型在磁暴期(2015年DOY076-078)TEC预报值RMSE和RD分别为0.83 TECU和3.13%,绝对和相对精度较LSTM模型分别提高1.49 TECU和10.25%;且NP模型RMSE优于1.5 TECU的比例达97.24%,远高于LSTM模型.NP模型预报值与CAS具有较好一致性和无偏性,偏差均值仅为-0.01 TECU,而LSTM模型预报值的均值偏大,偏差均值为1.49 TECU.从低纬到中纬度的三个纬度带内,NP模型RMSE分别为1.12、0.83和0.44 TECU,精度比LSTM模型提高1.94、1.56和1.23 TECU.整体上,在磁暴期NP模型预报性能明显优于LSTM模型,能够精细描述中国区域电离层TEC时空变化.展开更多
The global ionosphere maps(GIM)provided by the International GNSS Service(IGS)are extensively utilized for ionospheric morphology monitoring,scientific research,and practical application.Assessing the credibility of G...The global ionosphere maps(GIM)provided by the International GNSS Service(IGS)are extensively utilized for ionospheric morphology monitoring,scientific research,and practical application.Assessing the credibility of GIM products in data-sparse regions is of paramount importance.In this study,measurements from the Crustal Movement Observation Network of China(CMONOC)are leveraged to evaluate the suitability of IGS-GIM products over China region in 2013-2014.The indices of mean error(ME),root mean square error(RMSE),and normalized RMSE(NRMSE)are then utilized to quantify the accuracy of IGS-GIM products.Results revealed distinct local time and latitudinal dependencies in IGS-GIM errors,with substantially high errors at nighttime(NRMSE:39%)and above 40°latitude(NRMSE:49%).Seasonal differences also emerged,with larger equinoctial deviations(NRMSE:33.5%)compared with summer(20%).A preliminary analysis implied that the irregular assimilation of sparse IGS observations,compounded by China’s distinct geomagnetic topology,may manifest as error variations.These results suggest that modeling based solely on IGS-GIM observations engenders inadequate representations across China and that a thorough examination would proffer the necessary foundation for advancing regional total electron content(TEC)constructions.展开更多
电离层总电子含量(Total Electron Content,TEC)的预测是空间环境研究的重要内容,对卫星通讯和导航定位等有重要意义。设计了一个包含注意力机制的LSTM预测模型,利用连续5天的TEC来预测未来1天的TEC。在两个站点上将本文提出的模型与AR...电离层总电子含量(Total Electron Content,TEC)的预测是空间环境研究的重要内容,对卫星通讯和导航定位等有重要意义。设计了一个包含注意力机制的LSTM预测模型,利用连续5天的TEC来预测未来1天的TEC。在两个站点上将本文提出的模型与ARIMA和LSTM进行了对比实验。结果表明,所提模型的拟合程度可达0.9965,明显优于对比模型。展开更多
基于IGS全球观测站观测数据及IGS电离层格网数据,分析了2018年8月26日地磁暴事件引发的北半球地区电离层总电子含量(TEC)异常变化和观测数据质量变化。结果表明,北半球TEC异常存在纬度差异,高纬地区响应快,低纬地区异常值变化大;磁暴期...基于IGS全球观测站观测数据及IGS电离层格网数据,分析了2018年8月26日地磁暴事件引发的北半球地区电离层总电子含量(TEC)异常变化和观测数据质量变化。结果表明,北半球TEC异常存在纬度差异,高纬地区响应快,低纬地区异常值变化大;磁暴期间高纬地区观测数据周跳变化明显,数据完整率在北半球范围内都有下降,最大下降出现在高纬地区,达38.65%,数据质量与TEC异常变化规律较为一致。对GPS双频精密单点定位(Precise Point Positioning,PPP)结果进行分析,发现磁暴期间高纬地区测站动态PPP定位误差显著增大,水平和垂直均方根误差增至约0.7m及1.8m,静态PPP部分测站受影响。RTK观测在磁暴期间也存在受影响的可能,表现为固定率下降,定位误差增大。展开更多
恒温混匀仪是医学和生物学等领域中常用的仪器,精确的温度控制是确保恒温混匀仪正常工作的关键。本文提出了一种基于TEC(Thermal Electronic Cooler)的智能PID(Proportional Integral Derivative)温度控制系统制,通过离散测量数据库中...恒温混匀仪是医学和生物学等领域中常用的仪器,精确的温度控制是确保恒温混匀仪正常工作的关键。本文提出了一种基于TEC(Thermal Electronic Cooler)的智能PID(Proportional Integral Derivative)温度控制系统制,通过离散测量数据库中的多项式回归,对PID常数进行表征,为目标温度选择正确的值。结果表明:该系统的超调小于0.005℃,准确度小于±0.05℃,可确保在不同的环境温度下保持最佳的工作性能,实现最优的温控。展开更多
基金the National Key R&D Program of China(Grant No.2022YFF0503702)the National Natural Science Foundation of China(Grant Nos.42074186,41831071,42004136,and 42274195)+1 种基金the Natural Science Foundation of Jiangsu Province(Grant No.BK20211036)the Specialized Research Fund for State Key Laboratories,and the University of Science and Technology of China Research Funds of the Double First-Class Initiative(Grant No.YD2080002013).
文摘The global ionosphere maps(GIM)provided by the International GNSS Service(IGS)are extensively utilized for ionospheric morphology monitoring,scientific research,and practical application.Assessing the credibility of GIM products in data-sparse regions is of paramount importance.In this study,measurements from the Crustal Movement Observation Network of China(CMONOC)are leveraged to evaluate the suitability of IGS-GIM products over China region in 2013-2014.The indices of mean error(ME),root mean square error(RMSE),and normalized RMSE(NRMSE)are then utilized to quantify the accuracy of IGS-GIM products.Results revealed distinct local time and latitudinal dependencies in IGS-GIM errors,with substantially high errors at nighttime(NRMSE:39%)and above 40°latitude(NRMSE:49%).Seasonal differences also emerged,with larger equinoctial deviations(NRMSE:33.5%)compared with summer(20%).A preliminary analysis implied that the irregular assimilation of sparse IGS observations,compounded by China’s distinct geomagnetic topology,may manifest as error variations.These results suggest that modeling based solely on IGS-GIM observations engenders inadequate representations across China and that a thorough examination would proffer the necessary foundation for advancing regional total electron content(TEC)constructions.
文摘电离层总电子含量(Total Electron Content,TEC)的预测是空间环境研究的重要内容,对卫星通讯和导航定位等有重要意义。设计了一个包含注意力机制的LSTM预测模型,利用连续5天的TEC来预测未来1天的TEC。在两个站点上将本文提出的模型与ARIMA和LSTM进行了对比实验。结果表明,所提模型的拟合程度可达0.9965,明显优于对比模型。
文摘基于IGS全球观测站观测数据及IGS电离层格网数据,分析了2018年8月26日地磁暴事件引发的北半球地区电离层总电子含量(TEC)异常变化和观测数据质量变化。结果表明,北半球TEC异常存在纬度差异,高纬地区响应快,低纬地区异常值变化大;磁暴期间高纬地区观测数据周跳变化明显,数据完整率在北半球范围内都有下降,最大下降出现在高纬地区,达38.65%,数据质量与TEC异常变化规律较为一致。对GPS双频精密单点定位(Precise Point Positioning,PPP)结果进行分析,发现磁暴期间高纬地区测站动态PPP定位误差显著增大,水平和垂直均方根误差增至约0.7m及1.8m,静态PPP部分测站受影响。RTK观测在磁暴期间也存在受影响的可能,表现为固定率下降,定位误差增大。
文摘恒温混匀仪是医学和生物学等领域中常用的仪器,精确的温度控制是确保恒温混匀仪正常工作的关键。本文提出了一种基于TEC(Thermal Electronic Cooler)的智能PID(Proportional Integral Derivative)温度控制系统制,通过离散测量数据库中的多项式回归,对PID常数进行表征,为目标温度选择正确的值。结果表明:该系统的超调小于0.005℃,准确度小于±0.05℃,可确保在不同的环境温度下保持最佳的工作性能,实现最优的温控。
