电离层总电子含量TEC的监测与预报是近地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。使用基于Transformer(变形金刚)的iInformer(告密者)模型,提出中国区域电离层TEC短期预报新方法,且分别对磁静期与磁暴期电离层进行...电离层总电子含量TEC的监测与预报是近地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。使用基于Transformer(变形金刚)的iInformer(告密者)模型,提出中国区域电离层TEC短期预报新方法,且分别对磁静期与磁暴期电离层进行预测。为了分析短期电离层新模型预测效果,选取神经网络模型、线性模型、长短时记忆模型进行对比。结果表明,磁静期选定区域内iInformer模型有效适用于短期预测任务且预测精度明显优于其他对比模型,均方根误差在3个区域均低于1.45 TECU(total electron content units,总电子含量单位)。iInformer模型在应对不同数据量时,均能保持稳定的预测性能。特别是在数据集数量相对有限(少于2个月)的情况下,iInformer模型的预报精度显著优于其他模型。相较于单一数据源,多数据源下的iInformer模型预测精度有显著提升,提升幅度在2%~7.4%。展开更多
电离层TEC(Total Electron Content)扰动与多种扰动源相关联.2009年6至7月期间存在地震和日全食的扰动源.利用广州地区GPS监测网在2009年6至7月连续监测到的TEC数据,通过采用前15天数据的滑动窗口对数据进行处理,从时间序列和空间分布...电离层TEC(Total Electron Content)扰动与多种扰动源相关联.2009年6至7月期间存在地震和日全食的扰动源.利用广州地区GPS监测网在2009年6至7月连续监测到的TEC数据,通过采用前15天数据的滑动窗口对数据进行处理,从时间序列和空间分布两方面分析了华南地区电离层TEC扰动特征.结果显示,2009年6至7月华南地区电离层TEC扰动和该时期发生的地震以及日全食事件可能有关联;2009年7月多个地震发生引起的电离层扰动特征为,震前出现的是正异常,发震当天或震后有可能是正异常,也有可能是负异常;7月22日日全食当天TEC扰动为正异常,推测该正异常是地磁活动、地震活动及日全食综合效应的结果.展开更多
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
非制冷红外热像仪用于人体或者其他精准测温场景使用时,需要具有较高的测温精度,然而受外界环境温度变化和自身芯片发热的影响,会产生较为严重的温度漂移现象,从而导致测温精度受到一定的影响。为了消除这一影响,本文采用TEC作为非制冷...非制冷红外热像仪用于人体或者其他精准测温场景使用时,需要具有较高的测温精度,然而受外界环境温度变化和自身芯片发热的影响,会产生较为严重的温度漂移现象,从而导致测温精度受到一定的影响。为了消除这一影响,本文采用TEC作为非制冷探测器的制冷方案,通过Xilinx XC7A100T FPGA主控芯片合理设置带TEC的国产氧化钒红外探测器焦平面温度,实时检测探测器内部温度实现闭环高精度温控,使红外探测器尽可能工作在恒温状态。在完成基本成像的基础上,使用探测器原始数据计算并研究在5℃到55℃环境温度下打开温控和关闭温控条件下对测温精度的差异,实验结果为探测器在打开和关闭温控条件下测温精度平均为0.5℃和1.3℃,结果表明利用TEC对红外探测器做恒温控制有利于提高探测器原始数据的稳定性,可以一定程度提高测温精度。When the uncooled infrared thermal imager is used in the human body or other precise temperature measurement scenarios, it needs to have a high temperature measurement accuracy. However, due to the influence of the changes in the external environment temperature and the heating of its own chip, a relatively serious temperature drift phenomenon will occur, which will lead to a certain impact on the temperature measurement accuracy. In order to eliminate this effect, this paper uses thermoelectric cooler (TEC) as the refrigeration scheme of the uncooled detector, reasonably sets the focal plane temperature of the domestic vanadium oxide infrared detector with TEC through the Xilinx XC7A100T Field-Programmable Gate Array (FPGA) master chip, and real-time detects the internal temperature of the detector to achieve closed-loop high-precision temperature control, so that the infrared detector can work at a constant temperature as much as possible. On the basis of completing the basic imaging, the original data of the detector is used to calculate and study the difference in the temperature measurement accuracy under the conditions of opening and closing the temperature control under the ambient temperature of 5˚C to 55˚C. The experimental results show that the average temperature measurement accuracy of the detector under the conditions of opening and closing the temperature control is 0.5˚C and 1.3˚C. The results show that using TEC to control the temperature of the infrared detector is conducive to improving the stability of the detector’s original data and can improve temperature measurement accuracy to a certain extent.展开更多
The observations of Global Positioning System(GPS) scintillation,Total Electron Content(TEC)depletion,the periodic structure of TEC and Rate of TEC Index(ROTI) over south China were presented.Data were collected from ...The observations of Global Positioning System(GPS) scintillation,Total Electron Content(TEC)depletion,the periodic structure of TEC and Rate of TEC Index(ROTI) over south China were presented.Data were collected from GPS observations at stations of Shenzhen and Guangzhou from 2011 to 2012.This study reported that the ratio of simultaneous occurrences of TEC depletions with strong scintillations was higher than that of TEC depletions with weak scintillations in vernal and autumnal equinoxes of 2011 over South China.The number of the periodic structures of TEC with depletion contained was greater than that with no depletion contained corresponding to strong scintillations.The structure of the slab of plasma irregularities could be responsible for the simultaneous occurrences of TEC depletion with strong scintillations and ROTI.Before and during the occurrences of strong scintillation,there was Large-Scale Wave Structure(LSWS) which provided the seed ionization perturbation to trigger ESF irregularities and contributed to the periodic structure of TEC.展开更多
文摘电离层总电子含量TEC的监测与预报是近地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。使用基于Transformer(变形金刚)的iInformer(告密者)模型,提出中国区域电离层TEC短期预报新方法,且分别对磁静期与磁暴期电离层进行预测。为了分析短期电离层新模型预测效果,选取神经网络模型、线性模型、长短时记忆模型进行对比。结果表明,磁静期选定区域内iInformer模型有效适用于短期预测任务且预测精度明显优于其他对比模型,均方根误差在3个区域均低于1.45 TECU(total electron content units,总电子含量单位)。iInformer模型在应对不同数据量时,均能保持稳定的预测性能。特别是在数据集数量相对有限(少于2个月)的情况下,iInformer模型的预报精度显著优于其他模型。相较于单一数据源,多数据源下的iInformer模型预测精度有显著提升,提升幅度在2%~7.4%。
文摘电离层TEC(Total Electron Content)扰动与多种扰动源相关联.2009年6至7月期间存在地震和日全食的扰动源.利用广州地区GPS监测网在2009年6至7月连续监测到的TEC数据,通过采用前15天数据的滑动窗口对数据进行处理,从时间序列和空间分布两方面分析了华南地区电离层TEC扰动特征.结果显示,2009年6至7月华南地区电离层TEC扰动和该时期发生的地震以及日全食事件可能有关联;2009年7月多个地震发生引起的电离层扰动特征为,震前出现的是正异常,发震当天或震后有可能是正异常,也有可能是负异常;7月22日日全食当天TEC扰动为正异常,推测该正异常是地磁活动、地震活动及日全食综合效应的结果.
文摘非制冷红外热像仪用于人体或者其他精准测温场景使用时,需要具有较高的测温精度,然而受外界环境温度变化和自身芯片发热的影响,会产生较为严重的温度漂移现象,从而导致测温精度受到一定的影响。为了消除这一影响,本文采用TEC作为非制冷探测器的制冷方案,通过Xilinx XC7A100T FPGA主控芯片合理设置带TEC的国产氧化钒红外探测器焦平面温度,实时检测探测器内部温度实现闭环高精度温控,使红外探测器尽可能工作在恒温状态。在完成基本成像的基础上,使用探测器原始数据计算并研究在5℃到55℃环境温度下打开温控和关闭温控条件下对测温精度的差异,实验结果为探测器在打开和关闭温控条件下测温精度平均为0.5℃和1.3℃,结果表明利用TEC对红外探测器做恒温控制有利于提高探测器原始数据的稳定性,可以一定程度提高测温精度。When the uncooled infrared thermal imager is used in the human body or other precise temperature measurement scenarios, it needs to have a high temperature measurement accuracy. However, due to the influence of the changes in the external environment temperature and the heating of its own chip, a relatively serious temperature drift phenomenon will occur, which will lead to a certain impact on the temperature measurement accuracy. In order to eliminate this effect, this paper uses thermoelectric cooler (TEC) as the refrigeration scheme of the uncooled detector, reasonably sets the focal plane temperature of the domestic vanadium oxide infrared detector with TEC through the Xilinx XC7A100T Field-Programmable Gate Array (FPGA) master chip, and real-time detects the internal temperature of the detector to achieve closed-loop high-precision temperature control, so that the infrared detector can work at a constant temperature as much as possible. On the basis of completing the basic imaging, the original data of the detector is used to calculate and study the difference in the temperature measurement accuracy under the conditions of opening and closing the temperature control under the ambient temperature of 5˚C to 55˚C. The experimental results show that the average temperature measurement accuracy of the detector under the conditions of opening and closing the temperature control is 0.5˚C and 1.3˚C. The results show that using TEC to control the temperature of the infrared detector is conducive to improving the stability of the detector’s original data and can improve temperature measurement accuracy to a certain extent.
基金Supported by the National Natural Science Young Foundation of China(41704168)。
文摘The observations of Global Positioning System(GPS) scintillation,Total Electron Content(TEC)depletion,the periodic structure of TEC and Rate of TEC Index(ROTI) over south China were presented.Data were collected from GPS observations at stations of Shenzhen and Guangzhou from 2011 to 2012.This study reported that the ratio of simultaneous occurrences of TEC depletions with strong scintillations was higher than that of TEC depletions with weak scintillations in vernal and autumnal equinoxes of 2011 over South China.The number of the periodic structures of TEC with depletion contained was greater than that with no depletion contained corresponding to strong scintillations.The structure of the slab of plasma irregularities could be responsible for the simultaneous occurrences of TEC depletion with strong scintillations and ROTI.Before and during the occurrences of strong scintillation,there was Large-Scale Wave Structure(LSWS) which provided the seed ionization perturbation to trigger ESF irregularities and contributed to the periodic structure of TEC.
