Research on ionospheric plasma bubbles affecting GLS operation with SBAS information-assisted monitoringLi, Shifang; Yin, Ping
doi: 10.1088/1742-6596/3073/1/012004pmid: N/A
GLS is facing ionospheric delay anomalies that may lead to positioning errors exceeding the safety threshold, thereby threatening flight safety. SBAS usually uses ionospheric delay correction models to help users correct errors, but whether its data can be further used to monitor ionospheric threats still needs further research. This article uses multi-resolution ionospheric tomography technology and the Kriging method to statistically analyze the vertical delay difference between adjacent grid points in the low latitude region of China where ionospheric plasma bubbles appeared on February 21, 2021. The aim is to investigate whether SBAS ionospheric grid information can assist GLS in monitoring large spatial gradients. The research results indicate that when a certain grid is relatively close to the airport location and the edge of the ionospheric anomaly area, the absolute delay difference between the four grid points in the grid is greater than a certain threshold. It is judged that there is a large spatial gradient in this grid area, achieving the auxiliary effect of SBAS ionospheric grid information.
Evaluation and analysis of enhanced positioning performance for typical low earth orbit satellite constellation navigationYu, Xingwang; Luo, Daijian; Liu, Ji; Lv, Hongbo; Ding, Lele
doi: 10.1088/1742-6596/3073/1/012025pmid: N/A
In recent years, the development of low-orbit satellite navigation enhancement systems has been rapid. Low-orbit navigation satellites have relatively low orbital altitudes, high signal landing power, and fast speed, which are expected to solve the problem of long convergence time for real-time precise single-point positioning of GNSS. This article evaluates and analyses the enhanced positioning performance of typical low-orbit satellite constellations. The study selected three representative low-orbit satellite constellations, combined with GPS, BDS, and GALILEO global satellite navigation systems. By establishing evaluation models and simulating data, a comprehensive evaluation was conducted on the coverage performance of precise point positioning. The results indicate that low-orbit satellite constellations have significant advantages in navigation enhancement and can effectively shorten the convergence time of GNSS precise point positioning. At the same time, the study also revealed the performance differences between different constellation systems, providing important references for the design and optimization of future low-orbit satellite navigation systems.
Orbit monitoring and space environment simulations of the satellite M26 of BDSWang, Xiaoya; Jiang, Hu
doi: 10.1088/1742-6596/3073/1/012003pmid: N/A
No. 3 BeiDou navigation satellite system (No. 3 BDS) has been open to worldwide users since 2020. Its navigation service benefits more and more people from different countries. The satellite M26 is one of the standby satellites of BDS, which was sent into its operation orbit by the end of the year 2023. Its functions include stabilizing BDS, replacing the nearly retired satellite, and carrying out assessments of the new concept of GNSS. Due to the importance of satellite M26, authors have gathered the key orbit elements information; the orbit altitude, eccentricity and orbit inclination have been completely monitored and analyzed since its launch into working orbit. Based on the orbit elements, space environment effects for the first 271-day stay in orbit of M26 are simulated and space collision probability between M26 and other objects is studied. This work will partially support M26 to quickly join in the routine operation of BDS.
Numerical simulation of infrared radiation characteristics for turbofan engine exhaust plumeLi, Haonan; Feng, Rui; Li, Zhaoming; Liao, Yurong; Yang, Xinyan; Feng, Qirui
doi: 10.1088/1742-6596/3073/1/012012pmid: N/A
This study proposes a numerical simulation-based computational model for engine nozzle parameters, establishing a dynamic mapping relationship between nozzle performance parameters and spectral-domain characteristics by coupling flow field properties with spectral radiation analysis. A 2D axisymmetric nozzle and plume flow field model was developed using the Reynolds-Averaged Navier-Stokes (RANS) turbulence model and the Discrete Ordinates (DO) radiation transfer method. The gas composition distribution and infrared radiation characteristics of an aeroengine under specific bypass ratios (BPR) and fuel flow rates were analyzed. Results indicate: (1) The maximum plume temperature reaches 1090 K, with peak H2O and CO2 concentrations of 2.61% and 2.72%, respectively; (2) Long-wave infrared (8.3–20 μm) exhibits the largest radiative area, while mid-wave infrared (3.8–8.3 μm) achieves the highest radiative intensity.
Longitudinal leveling analysis and transition corridor study for tilt-rotor UAVsXi, Yangyang; Wang, Yujie; Sun, Shaofang; Lu, Yafei; Shao, Shuai
doi: 10.1088/1742-6596/3073/1/012019pmid: N/A
Tilt-rotor UAVs have the compound advantages of agile vertical takeoff and landing and high range time cruise, but also have the technical challenges of complex maneuver distribution and difficult flight control in transition mode. In this paper, a transition corridor calculation method based on steady-state leveling conditions for tilt-rotor UAVs is proposed, and the quantitative modeling and influencing factors of the transition corridor are investigated. First, a quadrotor tiltrotor UAV model is introduced, and then a longitudinal three-degree-of-freedom dynamics model is established. The transition corridor is defined as a safe velocity interval that satisfies the balance of force and moment under different rotor tilt angles. By introducing the least squares iterative algorithm to solve the constrained optimization problem containing parameters such as angle of attack, thrust distribution, rudder deflection, etc., the numerical computation flow of the transition corridor is constructed. In turn, the parameter sensitivity analysis is completed. The results of this paper provide a theoretical basis for the design of the transition control law and the optimization of the overall parameters of the tilt-rotor UAV. Future research can further improve the corridor’s robustness by combining the dynamic disturbance analysis and intelligent control strategy.
Improved SFFT algorithm for weak signal acquisition in BeiDou satellite navigationBai, Yu; Xing, Jianping; Sun, Peng; He, Siqi; Sun, Kaiping
doi: 10.1088/1742-6596/3073/1/012030pmid: N/A
Satellite signal acquisition is a critical component for BeiDou receivers to achieve PNT functionality, with its performance directly determining system availability in complex environments. Traditional time-frequency two-dimensional parallel search methods face two major bottlenecks: computational complexity increases dramatically when processing high-dynamic Doppler shifts, and under weak signal conditions, they struggle to meet high-sensitivity, low-power requirements due to the squaring loss effect and elevated noise floor. To address these challenges, this paper proposes an innovative acquisition architecture. 1) Combining an equivalent frequency compensation cyclic shift search mechanism with sparse Fourier transform (SFT), eliminating traditional two-dimensional traversal, and transforming Doppler search into cyclic shifts to reconstruct frequency search logic. 2) Introducing SFT to efficiently utilize the frequency-domain sparsity of BeiDou signals, computing only significant frequency components to optimize frequency-domain correlation efficiency. 3) Designing an improved differential coherent integration algorithm. For weak signal acquisition, differential coherent technology is applied by constructing a phase difference model between adjacent symbol periods, effectively canceling data bit transition effects and significantly suppressing noise floor elevation, achieving an SNR gain improvement of approximately 3 dB. Compared to conventional methods, under the same hardware conditions, the proposed solution reduces computational complexity by 62 % and improves acquisition sensitivity by 4 dB. For weak signals at -45 dBm, the acquisition success rate reaches 95 %. The novel “Doppler cyclic shift search-SFT” fusion architecture and differential coherent technology provide a new technical approach for efficient, high-sensitivity BeiDou signal acquisition, demonstrating significant theoretical breakthroughs and broad engineering application prospects.
Second order model based on time series clock bias decomposition and kalman filter estimation to alleviate Time synchronization attacksXu, Longwei; Zhang, Haizhen; Wu, Zhongwang
doi: 10.1088/1742-6596/3073/1/012029pmid: N/A
This article mainly studies the spoofing attack problem faced by the Beidou system, with a focus on the detection and mitigation methods of the second type of time synchronization attack. We propose a clock decomposition method based on the fusion of the binomial model and Kalman filter using time series clock decomposition. This method decomposes the clock bias sequence into trend and residual terms, uses a sliding window weighted least squares fitting binomial model to capture long-term trends, and dynamically tracks the short-term fluctuations of residual terms through Kalman filtering, achieving high-precision prediction of clock bias and dynamic correction of attack errors. The results indicate that the root mean square error of the improved method is reduced by one order of magnitude compared to the traditional binomial model.
Ship deformation monitoring method based on time-delay inertial measurementWang, Junjun; Liu, Xianjun; Wang, Yabo; Yang, Jian
doi: 10.1088/1742-6596/3073/1/012014pmid: N/A
For the ship deformation measurement system composed of two sets of inertial navigation systems, based on the traditional inertial measurement matching method, a method for monitoring the hull deformation based on time-delay inertial measurement is proposed. This method uses the output of the gyroscope to establish the measurement equation. Taking into account the influence of the time-delay error in practical applications on the accuracy of hull deformation monitoring, an extended dimension Kalman filter with the introduction of the time delay quantity is designed. The simulation results show that this method can effectively estimate the time delay error and significantly improve the accuracy of hull deformation monitoring.