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Performance of BDGIM, Klobuchar, NTCM-G and NeQuick-G models during 25TH solar cycle

Advances in space Research 2025年第10期75卷 7654-7667页

作者： Xu, Hanying Li, Min Yuan, Yunbin Zhang, Ting Zhang, Wenyao State Key Laboratory of Precision Geodesy and Positioning Innovation Academy for Precision Measurement Science and Technology CAS Wuhan China University of Chinese Academy of Sciences Beijing China

The ionospheric delay in Global Navigation Satellite System (GNSS) constitutes the majority of error sources in navigation and positioning and affects the accuracy for single-frequency (SF) users. Unlike dual-frequency users who reduce ionospheric delay by using the ionospheric elimination combination, SF users need to use external data sources such as the global broadcast ionospheric model to reduce the ionospheric delay. Moreover, with the arrival of 25th solar cycle, the increasing of solar activity level is further affecting the performance of ionospheric correction. To conduct a comprehensive evaluation of ionospheric models during the 25th solar cycle, we assessed four models: three operational models recommended by interface control documents (BDGIM, GPS Klobuchar, and NeQuick-G), as well as the NTCM-G model, which is based on Galileo broadcast coefficients. Our analysis utilized datasets from both continental and oceanic regions over the period from January 2020 to December 2023. For continental regions, the GNSS TEC data obtained from 33 individual monitoring stations are used as a reference data source. For oceanic regions, the TEC data obtained from JASON-3 altimeters are selected as the reference value. According to the comparison between JASON-3 TEC dataset and TEC dataset obtained from the four tested ionospheric models, the assessment demonstrates that the performances of tested models are strongly affected by solar activity. Specifically, BDGIM, Klobuchar, NTCM-G and NeQuick-G exhibit the RMS values of 4.36, 5.67, 5.06 and 5.84 TECU in low solar activity in 2020, and 9.99, 13.44, 10.64 and 9.50 TECU in high solar condition in 2023, respectively. In addition, as the validation against International GNSS Service (IGS) final Global Ionospheric Maps (GIMs) products shows, the average global RMS values of BDGIM, Klobuchar, NTCM-G and NeQuick-G are 5.23, 8.43, 4.95 and 6.22 TECU, respectively. BDGIM performs the best in low latitudes, NeQuick-G shows the h

关键词： Global positioning system

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The Influence of Modeling Accuracy of Spatial Harmonic Reducers on Fatigue Life Analysis

The Influence of Modeling Accuracy of Spatial Harmonic Reduc...

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2024 International Conference Optoelectronic Information and Optical Engineering, OIOE 2024

作者： Han, Jingyu Ruan, Ping Xie, Youjin Wang, Jiahao Peng, Bo Qu, Yun School of Optoelectronics University of Chinese Academy of Sciences Beijing100049 China Xi’an Institute of Optics and Precision Mechanics of CAS Xi’an710119 China Key Laboratory of Space Precision Measurement Technology of CAS Xi’an710119 China

ISBN: (数字)9781510688209

ISBN: (纸本)9781510688193

Harmonic reducers are widely used in various mechanisms of spacecraft, such as mechanism deployment, motion actuation, and precision pointing, due to their advantages of high single-stage reduction ratio, high transmission efficiency, small size, and large load capacity. For the application of spatial harmonic reducers in Solar Array Drive Assembly (SADA), in this paper, based on the envelope theory, a refined modeling of the commonly used double circular arc tooth profile harmonic reducer in space is completed. Static and transient dynamic finite element analysis of the complex harmonic model is carried out using ANSYS Workbench to study the motion and force distribution of the harmonic reducer under low-speed light-load conditions. The results are compared with those of the commonly used simplified tooth profile models to investigate the influence of tooth profile modeling on the calculation results, and a method to improve the convergence of the complex model is proposed. Based on the static and transient dynamic analysis results, fatigue analysis is conducted using nCode DesignLife, and the failure modes of the space harmonic reducer are identified, and conducted a lifetime prediction. © 2025 SPIE.

关键词： Failure modes

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Analysis of thermal radiation stray light in long-wave infrared refrigeration optical system 10

Analysis of thermal radiation stray light in long-wave infra...

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10th Symposium on Novel Optoelectronic Detection technology and Applications

作者： Wang, Xingfeng Liu, Kai Zhu, Chenxi Yu, Jiadong Liu, Zhaohui Zhou, Liang Xi'an Institute of Optics and Precision Mechanics Chinese Academy of Sciences Shaanxi Xi'an710119 China Key Laboratory of Space Precision Measurement Technology Chinese Academy of Sciences Shaanxi Xi'an710119 China

ISBN: (数字)9781510688155

ISBN: (纸本)9781510688148

Long wave infrared detection technology is widely used in environmental monitoring, medical diagnosis, fundamental research and other fields. However, the thermal radiation generated by the opto-mechanical structure of long wave infrared systems may cause additional response when reaching the detector, which degrades the system performance, and may result in detection failure in severe cases. In order to clarify the impact of thermal radiation on the detection performance and identify the key components that generate thermal radiation stray light (TRSL) in the system, in this work, a simulation model for a long wave infrared optical system operating at 7.7~9.3 μm is built, based on which the TRSL is studied. It is found that 91.24% of the TRSL of the system mainly comes from the filter, and the light is distributed throughout the entire field of view (FOV). The rest of TRSL is resulted from the planar beamsplitters and the imaging lenses groups (e.g., beamsplitters frame, the lens frame and lens tube), and the light is mainly distributed in the outer circle of the detector FOV. Furthermore, TRLS at discrete temperature between 293.15 K and 113.15 K is analyzed. When the temperature of the system is decreased to 173.15 K, the total amount of the TRLS, the TRLS of the filter and the rest of TRLS are also decreased to the order of 1e-6 W, 1e-6 W and 1e-7 W, respectively, which indicates that apart from refrigerating the optical system, filter refrigerating is also effective in multispectral infrared refrigeration optical system. © 2025 SPIE.

关键词： Stray light

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Ocean multi-GNSS kinematic PPP time transfer with Doppler observations and different system clock parameter solution strategies

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GPS Solutions 2025年第3期29卷 1-16页

作者： Han, Jinyang Zhang, Jie Zhong, Shiming Peng, Bibo Lu, Runmin Liang, Zihan Hu, Zecheng Gao, Fan Huang, Wenjian State Key Laboratory of Precision Geodesy Innovation Academy for Precision Measurement Science and Technology CAS Wuhan China National Geodetic Observatory Innovation Academy for Precision Measurement Science and Technology Chinese Academy of Sciences Wuhan China College of Earth and Planetary Sciences University of Chinese Academy of Sciences Beijing China School of Space Science and Physics Shandong University Weihai China

Precise Point Positioning (PPP) technology has been widely applied in the field of time transfer, but most current research on PPP time transfer focuses on static environments, with less research being conducted in kinematic oceanic environments. To explore the performance of Multi-global Navigation Satellite System (GNSS) kinematic PPP time transfer in ocean environments, a set of measured ocean GNSS data was selected, and four experimental strategies were employed to compare the time and frequency transfer performance of single GPS and multi-GNSS kinematic PPP under different elevation cutoff angles, as well as to examine the effects of different system clock parameter solution strategies and additional Doppler observation constraint positions on kinematic PPP time transfer. The experimental results show that: (1) when the common clock strategy is used to eliminate the influence of the clock source, the precision of ocean multi-GNSS kinematic PPP time transfer is better than 0.5 ns, the frequency stability at 1 s and 40,000 s averaging time is better than 5 × 10−11 and 9 × 10−15; (2) the clock parameter strategy of estimating a common clock and using Random Walk (RW) model to constrain the Inter System Biases (ISBs) for other systems has better time transfer precision and long-term frequency stability than the strategy for estimating each GNSS clock; (3) the use of Doppler observation constraint positions can improve the medium-term frequency stability, and when data interruption occurs, the time transfer precision is improved by more than 20%.

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Research on unit infrared scanning imaging technology based on combined galvanometer

Research on unit infrared scanning imaging technology based ...

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2024 International Conference on Optoelectronic Materials and Devices, ICOMD 2024

作者： Zhao, Jiannan Han, Weiqiang Fan, Zhenjie National Laboratory on Adaptive Optics Chinese Academy of Science Chengdu610209 China Key Laboratory of Science and Technology on Space Optoelectronic Precision Measurement Chinese Academy of Science Chengdu610209 China Institute of Optics and Electronics Chinese Academy of Science Chengdu610209 China University of Chinese Academy of Science Beijing100049 China

ISBN: (数字)9781510689046

ISBN: (纸本)9781510689039

To address the issues of low frame rates and non-uniformity in traditional infrared focal plane array imaging, a scanning imaging method based on infrared unit detectors is proposed. This method utilizes a combination of resonant mirrors and galvanometer-based scanning mirrors to sequentially acquire infrared point source information from the target. The collected data is then focused through optical lenses onto an infrared unit fiber-optic detector, where photoelectric conversion occurs to generate electrical signals for each pixel. Subsequently, a data acquisition card is employed to collect and process these electrical signals, resulting in the generation of infrared grayscale images. Experimental results demonstrate that the infrared point detector scanning imaging method enables wide-field and high-frame-rate imaging of infrared scenes. Furthermore, the simplicity and cost-effectiveness of point detector fabrication effectively overcome the high-cost limitations associated with traditional large focal plane array imaging, thereby promoting the broader application of infrared imaging technology. © 2025 SPIE.

关键词： Mirrors

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Influence of imaging quality of polarimetric imaging detection system on polarization measurement accuracy

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Optics and Laser technology 2025年 189卷

作者： Wang, Xingfeng Lu, Zhizhou Zhou, Liang Jiang, Kai Zhu, Chenxi Jia, Wentao Xie, Meilin Yang, Jianfeng Liu, Kai Xi'an Institute of Optics and Precision Mechanics Chinese Academy of Sciences Xi'an710119 China Key Laboratory of Space Precision Measurement Technology Chinese Academy of Sciences Xi'an710119 China Chongqing401332 China

Polarimetric imaging detection (PoID) has become an indispensable tool to acquire information efficiently and realize measurement precisely in a wide variety of fields. However, the quantitative evaluation model to characterize the relationship between system imaging quality and polarization measurement error in polarimetric imaging detection system (PoIDS) has been less explored, which limits further improvement of measurement accuracy. Here, based on scalar diffraction and aberration theory, we propose a quantitative model to evaluate the influence between the ideal and actual optical systems where the aberrations are in the same polarimetric modulation period. The proposed model incorporated the PoID methods based on Stokes parametric characterization is used to analyze the PoIDs for the observed solar magnetic field. The results show that when not being affected by distortion, the polarization measurement error would decrease with the decrease of the monochromatic aberration of the optical system. Furthermore, systematic errors exhibited stabilization when the root-mean-square (RMS) of the optical system aberration was reduced to below λ/38. Notably, for RMS values below λ/25, the system not only satisfied but exceeded the specified accuracy thresholds, a polarization background of 0.0005 solar continuum intensity (Ic) and a polarization crosstalk of 0.015. The proposed approach contributes a theoretical model for PoIDS, such as determination of design metric based on measurement accuracy and the evaluation of the measurement accuracy for actual system in the later stage. © 2025 Elsevier Ltd

关键词： Systematic errors

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The effect of solar activity on the ionosphere in the southern hemisphere's MSNA region

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Advances in space Research 2025年

作者： Meng, Di Zhao, Zhenzhen Zhang, Ting Wang, Kaixin Zhang, Zhihao Feng, Jiandi School of Civil Engineering and Geomatics Shandong University of Technology Zibo255000 China State Key Laboratory of Precision Geodesy Innovation Academy for Precision Measurement Science and Technology CAS Wuhan430077 China University of Chinese Academy of Sciences Beijing100049 China

Ionospheric empirical models have worse accuracy in describing the Mid-latitude Summer Night Anomaly (MSNA). MSNA variations are mainly affected by solar activity. The study uses GPS TEC data, CODE TEC data, and solar activity index data, applying time series and correlation analyses, to study the effects of different solar activities on the ionosphere in the southern hemisphere MSNA region. Results show that: (1) the MSNA phenomenon in the Southern Hemisphere usually occurs in January–February and November–December, and mainly occurs in the region of (60°S–70°S, 80°W–120°W), and the degree of longitudinal changes in its range is more prominent than that of latitudinal changes during the occurrence of MSNA. (2) The TEC usually reaches its maximum before midnight in years with low solar activity, and the number of days on which the TEC reaches its maximum before midnight is more than the number of days on which it reaches its maximum after midnight. (3) The MSNA index shows a low degree of linear correlation with the solar activity F10.7 index, with a correlation coefficient of only –0.20. © 2025 COSPAR

关键词： Ionospheric measurement

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Construction of Ghost Imaging LiDAR System Based on Dual Fast Mirrors

Construction of Ghost Imaging LiDAR System Based on Dual Fas...

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IEEE Information technology and Mechatronics Engineering Conference (ITOEC)

作者： Xie Meilin Cao Yu Guo Shan Li Sa Guo Min Wang Haitao Wang Zhaopeng Wang Lei Han Junfeng Key Laboratory of Space Precision Measurement Technology Xi’an Institute of Optics and Precision Mechanics Chinese Academy of Sciences Xi’an China Pilot National Laboratory for Marine Science and Technology Qingdao China Collaborative Innovation Center of Extreme Optics Shanxi University Taiyuan China

ISBN: (数字)9798331529482

ISBN: (纸本)9798331529499

Influenced by factors such as system bandwidth, rotational inertia, and tracking range in the GI LiDAR system, reliance on a large inertia tracking mechanism alone is challenging. Conversely, a small inertia tracking system may struggle to satisfy the system’s operational range needs. A composite axis control system is formed by combining a large inertia tracking system with a small inertia one to fulfill the tracking accuracy demands. In order to enhance the receiving aperture of the GI LiDAR system, this paper introduces a GI LiDAR system based on dual fast mirrors. Furthermore, a high-precision composite axis PAT control method is introduced to address the motion blur issue with the framework of the dual fast mirrors-based GI LiDAR system.

关键词： Laser radar Accuracy Mechatronics Tracking Optical design Apertures Laser stability Optical imaging Laser modes Mirrors

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Research on the Collaborative Control Method of the Turntable and the High-Speed Momentum wheel under High Inertia Load

Research on the Collaborative Control Method of the Turntabl...

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IEEE Information technology and Mechatronics Engineering Conference (ITOEC)

作者： Cao Yu Li Sa Gao Xiong Guo Shan Wang Zhaopeng Wang Haitao Wan Wei Xie Meilin Key Laboratory of Space Precision Measurement Technology Xi'an Institute of Optics and Precision Mechanics Chinese Academy of Sciences Xi'an China Pilot National Laboratory for Marine Science and Technology Qingdao China Collaborative Innovation Center of Extreme Optics Shanxi University Taiyuan China University of Chinese Academy of Sciences Beijing China

ISBN: (数字)9798331529482

ISBN: (纸本)9798331529499

Reconnaissance and surveillance satellites are an important part of a country's strategic early warning system and also a key means for the construction and development of the ability to control space information rights. Electronic reconnaissance satellites, as an important link in intelligence reconnaissance and strategic early warning, rely on their wide frequency band, high-timeliness information transmission, and intelligent information processing, and possess relatively strong support capabilities. They have become the foundation and support of the current informationized combat system. In order to obtain ground intelligence comprehensively and effectively, electronic reconnaissance satellites must adopt large receiving antennas with high sensitivity. In response to the urgent need for payload lightweighting at present, it is necessary to study the collaborative control method of the turntable and the high-speed despun Momentum wheel under high inertia load. The despun collaborative control of the turntable and the high-speed Momentum wheel usually requires multiple processors to achieve the synchronous control of the turntable and the Momentum wheel respectively. In this paper, through the DSP, a control method that nests the system-wide algorithm interrupt and the high-speed Momentum wheel motor commutation interrupt is adopted to realize the real-time four-quadrant control of the turntable and the high-speed Momentum wheel. Finally, after experimental tests, when the turntable rotation speed is 90°/s and the load inertia is 60 kg, the residual torque of the turntable subsystem is less than 0.1 Nm, and the speed stability of the turntable reaches 0.2°/s.

关键词： Torque Satellites Surveillance Wheels Collaboration Information processing Reconnaissance Control systems Steady-state Testing

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Generating Reliable Initial Velocity Models for Full-waveform Inversion with Well and Structural Constraints

arXiv

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arXiv 2025年

作者： Zhang, Qingchen Cheng, Shijun Chen, Wei Mao, Weijian Key Laboratory of Exploration Technology for Oil and Gas Resources of Ministry of Education Yangtze University Wuhan430100 China Cooperative Innovation Center of Unconventional Oil and Gas Ministry of Education Yangtze University Hubei Province Wuhan430100 China Division of Physical Science and Engineering King Abdullah University of Science and Technology Thuwal23955-6900 Saudi Arabia Research Center for Computational and Exploration Geophysics State Key Laboratory of Precision Geodesy Innovation Academy for Precision Measurement Science and Technology CAS Wuhan430077 China

Full waveform inversion (FWI) plays an important role in velocity modeling due to its high-resolution advantages. However, its highly non-linear characteristic leads to numerous local minimums, which is known as the cycle-skipping problem. Therefore, effectively addressing the cycle-skipping issue is crucial to the success of FWI. Well-log data contain rich information about subsurface medium parameters, providing inherent advantages for velocity modeling. Traditional well-log data interpolation methods to build velocity models have limited accuracy and poor adaptability to complex geological structures. This study introduces a well interpolation algorithm based on a generative diffusion model (GDM) to generate initial models for FWI, addressing the cycle-skipping problem. Existing convolutional neural network (CNN)-based methods face difficulties in handling complex feature distributions and lack effective uncertainty quantification, limiting the reliability of their outputs. The proposed GDM-based approach overcomes these challenges by providing geologically consistent well interpolation while incorporating uncertainty assessment. Numerical experiments demonstrate that the method produces accurate and reliable initial models, enhancing FWI performance and mitigating cycle-skipping issues. Copyright © 2025, The Authors. All rights reserved.

关键词： Well logging

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