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165 results on '"Yang, Xiaojia"'

43. Stress corrosion cracking behavior of high-strength mooring-chain steel in the SO2-polluted coastal atmosphere.

Author

Liu, Menghao, Liu, Zhiyong, Du, Cuiwei, Zhan, Xiaoqin, Yang, Xiaojia, and Li, Xiaogang

Abstract

21Cr2NiMo steel is widely used to stabilize offshore oil platforms; however, it suffers from stress-corrosion cracking (SCC). Herein, we studied the SCC behavior of 21Cr2NiMo steel in SO2-polluted coastal atmospheres. Electrochemical tests revealed that the addition of SO2 increased the corrosion current. Rust characterization showed that SO2 addition densfied the corrosion products and promoted pitting. Furthermore, slow strain rate tests demonstrated a high susceptibility to SCC in high SO2 contents. Fracture morphologies revealed that the stress-corrosion cracks initiated at corrosion pits and the crack propagation showed transgranular and intergranular cracking modes. In conclusion, SCC is mix-controlled by anodic dissolution and hydrogen embrittlement mechanisms. [ABSTRACT FROM AUTHOR]

Published
2022
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46. Modeling of GBAS VDB Signal Propagation Path Loss in Airport Using Parabolic Equation

Author

Yang Zhengbo, Yang Xiaojia, Ye Jiaquan, Jing Liu, and Ping Yang

Subjects
Radio propagation, GNSS augmentation, Computer science, Control theory, Transmitter, Path loss, Signal
Abstract

In the near future, the Ground Based Augmentation System (GBAS) is intending to provide navigation service for aircrafts and vehicles operation in apron, which requires more stringent navigation performance. The artificial structures in airport will affect the characteristics of signal in space of GBAS Very high frequency Data Broadcast (VDB) transmitter. In order to evaluate their effects on the performance of GBAS VDB, path loss of VDB signal propagating in airport must be analyzed. In cylindrical coordinates, the three dimension (3D) Parabolic Equation (PE) method combing with grid tessellation is proposed to predict GBAS VDB signal propagation path loss in airport. This method can take the lateral propagation effects into consideration and achieve a uniform solution resolution in all azimuths along the radical direction. Simulation results demonstrate the efficiency and numerical stability of this method.

Published
2019

47. A Multi-Navigation Data Fusion Algorithm for Vehicle Localization in Airport

Author

Yang Xiaojia, Ye Jiaquan, Ping Yang, Jing Liu, and Yang Zhengbo

Subjects
0303 health sciences, Kullback–Leibler divergence, GNSS augmentation, Computer science, Real-time computing, 020206 networking & telecommunications, Ground based augmentation system, 02 engineering and technology, Sensor fusion, 03 medical and health sciences, Robustness (computer science), Data fusion algorithms, 0202 electrical engineering, electronic engineering, information engineering, Multipath propagation, 030304 developmental biology
Abstract

Precise and robust localization is an essential factor for the guidance of vehicles driving in the airport in low visibility operation. Ground Based Augmentation System (GBAS) solution can provide satisfactory positioning in open areas, however, its performance suffered in apron area due to the effects of multipath. In order to have safe and efficient localization for vehicles, a multi-navigation data fusion algorithm is employed by using Kullback-Leibler Divergence (KLD) metric, we show how to combine GBAS and other sensory information to acquire more reliable localization. Simulation results indicate the accuracy and robustness of the proposed method.

Published
2019

48. Low Pass Filters Design Using Hybrid Taguchi and PSO Optimization Method

Author

Yang Xiaojia, Yang Zhengbo, Ye Jiaquan, Ping Yang, and Jing Liu

Subjects
Optimal design, Computer science, Low-pass filter, MathematicsofComputing_NUMERICALANALYSIS, Process (computing), Particle swarm optimization, 02 engineering and technology, 010501 environmental sciences, 01 natural sciences, Taguchi methods, GNSS applications, Control theory, 0202 electrical engineering, electronic engineering, information engineering, 020201 artificial intelligence & image processing, 0105 earth and related environmental sciences, Numerical stability, Premature convergence
Abstract

Low pass filters are useful and necessary for direct conversion GNSS SDR, which is reconfigurable for multi-band navigation satellite systems. This paper addresses a novel low pass filter optimal design methodology, which using hybrid Taguchi and particle swarm optimization (PSO). In the optimization process, the Taguchi method is utilized to overcome the premature convergence and stagnation problem of PSO. A comparison of simulation results reveals the method’s efficiency as well as its numerical stability.

Published
2019

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