The Global Positioning System(GPS)satellite constellation has provided long-term observations of energetic elec trons in Earth’s radiation belts,but inconsistencies among different satellites limit the direct use of ...The Global Positioning System(GPS)satellite constellation has provided long-term observations of energetic elec trons in Earth’s radiation belts,but inconsistencies among different satellites limit the direct use of their combined measurements.A comparative analysis of electron flux data from year 2000 to 2020 reveals significant deviations for several satellites,particularly NS41 and NS48 in low-flux regions,as well as scattered observations from satellites such as NS74 and NS69.These discrepancies highlight the necessity of cross-calibration to ensure data consistency.To address this,we conducted the first systematic cross-calibration of energetic electron fluxes from 25 GPS satel lites.Taking the 2.0 MeV average unidirectional differential electron fluxes and the≥2.0 MeV omnidirectional integral electron fluxes as examples,we adopted the conjunction method in magnetic coordinates(Lm,B/B0)(Lm:McIlwain L-shell parameter,B/B0:magnetic field ratio)and applied cubic polynomial fitting to achieve unified calibration using NS59 as the reference.For the 2.0 MeV differential electron fluxes,the Root-Mean-Square Deviation(RMSD)before cal ibration is on average 3.08 times larger than that after calibration,while the Correlation Coefficient(CC)increases by a factor of 1.14 on average.For the≥2.0 MeV integral electron fluxes,the corresponding values are 1.68 and 1.01,respectively.This method can be extended to other energy channels and satellites.The calibrated dataset facilitates quantitative analysis and modeling of variations in the high-energy electron distribution in medium Earth orbits.展开更多
为精准识别港口群内部公路集疏运范围,基于集疏运货车GPS数据,提出一种识别港口公路运输模式下服务范围的方法,以支撑港口群内部竞争与合作策略的决策。在对海量集疏运货车GPS数据清洗和OD(Origin-Destination)信息提取的基础上,基于DBS...为精准识别港口群内部公路集疏运范围,基于集疏运货车GPS数据,提出一种识别港口公路运输模式下服务范围的方法,以支撑港口群内部竞争与合作策略的决策。在对海量集疏运货车GPS数据清洗和OD(Origin-Destination)信息提取的基础上,基于DBSCAN(Density-Based Spatial Clustering of Applications with Noise)空间聚类算法识别出核心节点;依据节点-港口的运输频次确定OD选择概率,采用Delaunay三角剖分方法界定港口在公路运输模式下的精确服务范围。福厦泉港口群的案例结果显示:公路运输模式下3个港口的服务范围存在不同特征,腹地重叠和孤岛现象明显;竞争最激烈的区域出现在较深入的内陆区域,且服务范围的重叠现象主要出现在港口各自服务范围的末端区域。研究发现:优化运输网络与差异化定位是提升港口竞争力的关键。展开更多
星载全球导航卫星系统(global navigation satellite system,GNSS)是实现低轨卫星实时精密定轨的有效技术手段。Sentinel-6A海洋测高卫星搭载了GPS/Galileo双模接收机,为相关研究提供了数据支撑。GNSS广播星历存在较大误差,对低轨卫星...星载全球导航卫星系统(global navigation satellite system,GNSS)是实现低轨卫星实时精密定轨的有效技术手段。Sentinel-6A海洋测高卫星搭载了GPS/Galileo双模接收机,为相关研究提供了数据支撑。GNSS广播星历存在较大误差,对低轨卫星实时定轨带来了不利影响。通过额外估计空间信号测距误差(signal in space ranging error,SISRE)参数对广播星历误差进行补偿,进而提高Sentinel-6A卫星实时定轨性能。结果表明,利用SISRE参数进行补偿之后,星载GPS、Galileo和GPS+Galileo的Sentinel-6A卫星实时定轨三维精度分别达到19.8、13.9和13.3 cm,提升了48%、33%和32%;收敛时间均缩短了25%以上;载波相位观测值残差均方根(root mean square,RMS)减小了70%~90%。证明该方法是补偿低轨卫星实时定轨中广播星历误差的有效手段。展开更多
在面对复杂的安装环境时,现有无线远传大口径水表存在安装位置不清晰进而定位难的问题,严重制约了智慧水务管理的效率与准确性。为此,本文提出一款基于北斗/GPS双模定位的无线远传大表设计。在简要概述无线远传水表技术的发展史与北斗GP...在面对复杂的安装环境时,现有无线远传大口径水表存在安装位置不清晰进而定位难的问题,严重制约了智慧水务管理的效率与准确性。为此,本文提出一款基于北斗/GPS双模定位的无线远传大表设计。在简要概述无线远传水表技术的发展史与北斗GPS双模定位模块的基础上,对水表的整体结构、硬件和软件进行设计,并通过实验验证了其各项功能。此水表采用窄带物联网(Narrow Band Internet of Things,NBIoT)通信技术与北斗/GPS双模卫星导航技术的融合方案,突破了传统无线远传水表在后期维护与复杂环境适应性方面的多重瓶颈,提升了智慧水务管理的效率和准确性。展开更多
基金funded by the China Postdoctoral Science Foundation 2025M784268the National Natural Science Foundation of China Grants 42441809+1 种基金the National Natural Science Foundation of China Project U2106201the NSFC Regional Innovation and Development Joint Fund U25A20784.
摘要The Global Positioning System(GPS)satellite constellation has provided long-term observations of energetic elec trons in Earth’s radiation belts,but inconsistencies among different satellites limit the direct use of their combined measurements.A comparative analysis of electron flux data from year 2000 to 2020 reveals significant deviations for several satellites,particularly NS41 and NS48 in low-flux regions,as well as scattered observations from satellites such as NS74 and NS69.These discrepancies highlight the necessity of cross-calibration to ensure data consistency.To address this,we conducted the first systematic cross-calibration of energetic electron fluxes from 25 GPS satel lites.Taking the 2.0 MeV average unidirectional differential electron fluxes and the≥2.0 MeV omnidirectional integral electron fluxes as examples,we adopted the conjunction method in magnetic coordinates(Lm,B/B0)(Lm:McIlwain L-shell parameter,B/B0:magnetic field ratio)and applied cubic polynomial fitting to achieve unified calibration using NS59 as the reference.For the 2.0 MeV differential electron fluxes,the Root-Mean-Square Deviation(RMSD)before cal ibration is on average 3.08 times larger than that after calibration,while the Correlation Coefficient(CC)increases by a factor of 1.14 on average.For the≥2.0 MeV integral electron fluxes,the corresponding values are 1.68 and 1.01,respectively.This method can be extended to other energy channels and satellites.The calibrated dataset facilitates quantitative analysis and modeling of variations in the high-energy electron distribution in medium Earth orbits.
摘要为精准识别港口群内部公路集疏运范围,基于集疏运货车GPS数据,提出一种识别港口公路运输模式下服务范围的方法,以支撑港口群内部竞争与合作策略的决策。在对海量集疏运货车GPS数据清洗和OD(Origin-Destination)信息提取的基础上,基于DBSCAN(Density-Based Spatial Clustering of Applications with Noise)空间聚类算法识别出核心节点;依据节点-港口的运输频次确定OD选择概率,采用Delaunay三角剖分方法界定港口在公路运输模式下的精确服务范围。福厦泉港口群的案例结果显示:公路运输模式下3个港口的服务范围存在不同特征,腹地重叠和孤岛现象明显;竞争最激烈的区域出现在较深入的内陆区域,且服务范围的重叠现象主要出现在港口各自服务范围的末端区域。研究发现:优化运输网络与差异化定位是提升港口竞争力的关键。
摘要星载全球导航卫星系统(global navigation satellite system,GNSS)是实现低轨卫星实时精密定轨的有效技术手段。Sentinel-6A海洋测高卫星搭载了GPS/Galileo双模接收机,为相关研究提供了数据支撑。GNSS广播星历存在较大误差,对低轨卫星实时定轨带来了不利影响。通过额外估计空间信号测距误差(signal in space ranging error,SISRE)参数对广播星历误差进行补偿,进而提高Sentinel-6A卫星实时定轨性能。结果表明,利用SISRE参数进行补偿之后,星载GPS、Galileo和GPS+Galileo的Sentinel-6A卫星实时定轨三维精度分别达到19.8、13.9和13.3 cm,提升了48%、33%和32%;收敛时间均缩短了25%以上;载波相位观测值残差均方根(root mean square,RMS)减小了70%~90%。证明该方法是补偿低轨卫星实时定轨中广播星历误差的有效手段。
摘要在面对复杂的安装环境时,现有无线远传大口径水表存在安装位置不清晰进而定位难的问题,严重制约了智慧水务管理的效率与准确性。为此,本文提出一款基于北斗/GPS双模定位的无线远传大表设计。在简要概述无线远传水表技术的发展史与北斗GPS双模定位模块的基础上,对水表的整体结构、硬件和软件进行设计,并通过实验验证了其各项功能。此水表采用窄带物联网(Narrow Band Internet of Things,NBIoT)通信技术与北斗/GPS双模卫星导航技术的融合方案,突破了传统无线远传水表在后期维护与复杂环境适应性方面的多重瓶颈,提升了智慧水务管理的效率和准确性。