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131 results on '"Yu, Zhangjun"'

5. High Spatial Resolution Distributed Birefringence Measurement in Km Level Length PM Fiber Based on Polarization OFDR

Author

Lin, Cuofu, Xie, Dongcheng, Yang, Jun, Zhang, Xiang, Zou, Chen, Yu, Zhangjun, Wang, Yuncai, and Qin, Yuwen

Abstract

This paper proposes a distributed birefringence measurement method for long-distance polarization maintaining fiber (PMF) based on polarization optical frequency domain reflectometry (P-OFDR). Distinguished from the existing ways, the method characterizes birefringence by the internal strain of the PMF, and cuts off the dependence of birefringence measurements on the wavelength of the interrogated laser. It obtains the internal strain through the cross-correlation of the Rayleigh backscattering (RBS) spectra from the two orthogonal axes of polarization. The measured internal strain is converted to birefringence according to the parameters of the PMF. In addition, a delay correction method is proposed for overcome the degradation of the RBS spectra correlation due to birefringence delay, and extends the measurement distance. In the experiments, the distributed birefringence measurement in 5020 m PMF is achieved with a spatial resolution of 10 cm and a measurement accuracy of 1.4 × 10−7. The single sweep is faster at only 1 second and offers excellent stability. Finally, we demonstrate the application of the method in a fiber coil. The measured distributed birefringence of the coil is symmetric. Stress concentration due to temperature variations and winding defects is clearly visible in the results. The method is helpful for quality evaluation of polarization maintaining devices and PMF, as well as potentially applying to birefringence-based distributed sensing.

Published
2024
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6. Distributed Chromatic Dispersion Compensation Method Based on Mismatch Factor for High Resolution OFDR

Author

Zou, Chen, Xie, Dongcheng, Lin, Cuofu, Yu, Zhangjun, Zhu, Yunlong, Zhu, Yao, Dang, Fanyang, Yuan, Yonggui, Yang, Jun, Wang, Yuncai, and Qin, Yuwen

Abstract

Optical frequency domain reflectometry (OFDR) can provide a powerful tool for fiber components and devices diagnosis and characterization. However, apart from laser source phase noise, the impact of the chromatic dispersion effect on the system is severely increased with the measurement length and laser tunable range. We propose a distributed chromatic dispersion compensation method for the device under the test (DUT) with complex structures containing different dispersive media connections in OFDR. Based on the mismatch factor (which is related to the difference in dispersion coefficient between the reference fiber and DUT), chromatic dispersion errors in the signal from different dispersion mediums can be compensated segment by segment by constructing the dispersion phase error signal. The compensation method is evaluated by experiments on DUT with multiple material dispersion (including reduced-cladding single-mode fiber (RC SMF) and dispersion compensation fiber (DCF)) and various measurement distances. Finally, we experimentally analyzed the internal reflection of a multifunctional integrated optical chip (MFIOC). Sweeping the laser source by 160 nm, the input coupling, output coupling, beam splitting, and defect points are individually revealed with a high resolution better than 15 $\mu$m. We believe that this approach enables high-precision quantitative measurements as well as accurate identification and localization of fault diagnosis for optical fibers and devices.

Published
2024
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14. Zero-Velocity Update-Based GNSS/IMU Tightly Coupled Algorithm with the Constraint of the Earth's Rotation Angular Velocity for Cableway Bracket Deformation Monitoring.

Author

Zhang, Song, Zhang, Qiuzhao, Yu, Ruipeng, Yu, Zhangjun, Zhang, Chu, and He, Xinyue

Subjects
CONSTRAINT algorithms, ANGULAR velocity, GLOBAL Positioning System, ROTATION of the earth, KALMAN filtering, WIRE rope, ROTATIONAL motion
Abstract

Cableways have been widely used in industrial areas, cities, and scenic spots due to their advantages, such as being a convenient mode of transportation, time-saving, labor-saving, and low cost, as well as offering environmental protection. To ensure the safe operation of a cableway, based on the characteristic that the velocity of the cableway bracket is approximately zero in a static deformation monitoring environment, a deformation monitoring method called zero velocity update (ZUPT)-based GNSS/IMU tightly coupled algorithm with the constraint of the Earth's rotation angular velocity was proposed. The proposed method can effectively solve the problem of a single GNSS being unable to output attitude, which is directly related to the status of wire ropes and cable cars. Meanwhile, ZUPT is used to restrain the Kalman filter's divergence when IMU is stationary. However, the improvements of ZUPT on attitude are not obvious, so the constraint of the Earth's rotation angular velocity was applied. The performance of the proposed method was evaluated through monitoring the cableway bracket of the Yimeng Mountain Tourism area in Shandong. Compared with the ZUPT-based GNSS/IMU tightly coupled algorithm (ZUPT-TC), the proposed method can further constrain the error accumulation of IMU while stationary and, therefore, it can provide reliable position and attitude information on cableway brackets. [ABSTRACT FROM AUTHOR]

Published
2023
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24. Singular value decomposition‐based iterative robust cubature Kalman filtering and its application for integrated global positioning system/strapdown inertial navigation system navigation

Author

Vladimír Sedlák, Yunrui Zhang, Yu Zhangjun, Nanshan Zheng, and Qiuzhao Zhang

Subjects
cubature Kalman filter, integrated navigation system, Cubature kalman filter, Computer science, business.industry, singular value decomposition, TK5101-6720, Kalman filter, non‐linear filter, Control theory, Singular value decomposition, Telecommunication, Global Positioning System, Electrical and Electronic Engineering, business, Inertial navigation system
Abstract

The issue of non‐linear robust state estimation in the integration of a strapdown inertial navigation system and global positioning system is addressed in this study. Based on the cubature Kalman filtering frame, a non‐linear robust filter called a robust cubature Kalman filter (RCKF) was introduced to address the outliers and the inaccurate model. It has been found that the determination of an optimal restriction parameter is crucial for maintaining the robustness and accuracy of the non‐linear robust filter. Unfortunately, the value of this restriction parameter is always determined by experience. In this study, an iterative strategy was proposed to adaptively attain the optimal restriction parameter without much previous experience. To improve the computational stability of the iterative non‐linear robust filter, a singular value decomposition strategy was adopted simultaneously. Two case studies indicate that the iterative RCKF can achieve greater robustness and accuracy using the methodology discussed in this study.

Published
2021

29. Distributed Polarization Measurement for Fiber Sensing Coils: A Review

Author

Yu Zhangjun, Dang Fanyang, Jun Yang, Zhang Xiang, Yuncai Wang, Yonggui Yuan, Yuwen Qin, Lin Cuofu, and Libo Yuan

Subjects
White light interferometry, Optical fiber, Materials science, law, Dynamic range, Electromagnetic coil, Acoustics, Frequency domain, Polarization-maintaining optical fiber, Time domain, Spatial frequency, Atomic and Molecular Physics, and Optics, law.invention
Abstract

Distributed polarization measurement is a significant way to evaluate polarization-maintaining fiber. It can assess the fiber's polarization preserving ability and locate internal defects and external perturbations of a long-distance PM fiber. Distributed polarization crosstalk of a fiber-optic polarization device accurately describes its time-dependent optical performance. Therefore, distributed polarization measurement technology can be used to predict and prevent the performance degradation and failure. However, the remaining shortcomings of existing measurement methods are low dynamic range, short measurement length, inadequate spatial resolution, and low diagnostic ability. This paper reviews recent advances in solving the above issues and presents ways to obtain high performances: a dynamic range > 90 dB, a measurement length > 10 km, a full range spatial resolution < 10 cm, and developments in time domain, frequency domain, and time-frequency domain diagnosis methods. All these high-performance techniques have led to more effective diagnosis of fiber optic sensing coils. This can be demonstrated by a series of comparative measurements and analysis of three PM fiber optic sensing coils in various configurations such as a randomly-wound spool of fiber and a free-standing coil quadrupole-pattern-wound from it, a second coil with and without a flange at various temperatures, and a third coil spliced to a Y waveguide. Each is one of the key configurations during the production processes or the application of the fiber sensing coil. The technical progress reviewed here will greatly promote the development, production, and application of fiber sensing coils.

Published
2021

30. High Accuracy Distributed Polarization Extinction Ratio Measurement For a Polarization-Maintaining Device With Strong Polarization Crosstalk

Author

Jun Yang, Pengbai Xu, Xinyong Dong, Yonggui Yuan, Yu Zhangjun, Yuwen Qin, Yuncai Wang, Libo Yuan, and Chengcheng Hou

Subjects
Physics, White light interferometry, Interferometry, Optics, Extinction ratio, Electromagnetic coil, business.industry, Device under test, Polarization-maintaining optical fiber, Polarization (waves), Residual, business, Atomic and Molecular Physics, and Optics
Abstract

Polarization extinction ratio (PER) is a quantitative indicator of the polarization-maintaining (PM) ability of a device. In this work, we present a distributed PER measurement method based on white-light interferometry. It can accurately measure the PER distribution of a PM device even in the presence of strong polarization crosstalk. We show that the distributed PER can be expressed as the reciprocal of the accumulated polarization crosstalk along the device. Thus, the PER distribution of a PM device can be calculated from the distributed polarization crosstalk. In the presence of strong polarization crosstalk, we introduced a concept of polarization crosstalk induced loss to prove that there is a significant error of the measured distributed polarization crosstalk. The error can be accurately estimated and be calibrated out from the measurement result. To verify the measurement method and the calibration accuracy, we used a commercial PER meter that can only measure the total PER of a device as the reference. We simulated a quasi-distributed PER device under test (DUT) by successively splicing 15 pieces of PM fibers and measured its total PER after splicing each piece of fiber. The calculated distributed PER of the DUT after error calibration matches well with the quasi-distributed result at the corresponding locations. Finally, we applied the method to measure the distributed PER and total PER of a PM fiber coil. After error calibration, the residual error (i.e., the difference with the commercial PER meter) in the total PER, thus of the distributed PER, is less than 0.1 dB.

Published
2021

31. Principles and Applications of Seismic Monitoring Based on Submarine Optical Cable.

Author

Yu, Junzhe, Xu, Pengbai, Yu, Zhangjun, Wen, Kunhua, Yang, Jun, Wang, Yuncai, and Qin, Yuwen

Subjects
OPTICAL sensors, SUBMARINE cables, FIBER Bragg gratings, OPTICAL interferometers
Abstract

Submarine optical cables, utilized as fiber-optic sensors for seismic monitoring, are gaining increasing interest because of their advantages of extending the detection coverage, improving the detection quality, and enhancing long-term stability. The fiber-optic seismic monitoring sensors are mainly composed of the optical interferometer, fiber Bragg grating, optical polarimeter, and distributed acoustic sensing, respectively. This paper reviews the principles of the four optical seismic sensors, as well as their applications of submarine seismology over submarine optical cables. The advantages and disadvantages are discussed, and the current technical requirements are concluded, respectively. This review can provide a reference for studying submarine cable-based seismic monitoring. [ABSTRACT FROM AUTHOR]

Published
2023
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38. A State-Domain Robust Chi-Square Test Method for GNSS/INS Integrated Navigation

Author

Ke Yu, Nanshan Zheng, Yu Zhangjun, and Qiuzhao Zhang

Subjects
Article Subject, Covariance matrix, Computer science, Test method, Kalman filter, Fault detection and isolation, Domain (software engineering), Control and Systems Engineering, GNSS applications, Robustness (computer science), Singular value decomposition, T1-995, Electrical and Electronic Engineering, Instrumentation, Algorithm, Technology (General)
Abstract

Aiming at abrupt faults in GNSS/INS integrated systems in complex environments, classical fault detection algorithms are mostly developed from the measurement domain. A robust chi-square test method based on the state domain is proposed in this paper. The fault detection statistic is built based on the difference between the prior state estimation and the posterior state estimation in Kalman filtering. To improve the calculation stability, singular value decomposition (SVD) is used to factor the covariance matrix of the difference. The relevant formulas of the proposed method were theoretically derived, and the relationship between the proposed method and the existing innovation chi-square test method was revealed. The proposed method was compared with state-of-the-art chi-square test methods and verified by GNSS/INS integrated navigation experiments using simulation data and real data. The experimental results show that the proposed method (a) directly works in the state domain, (b) does not require the known real system state, (c) has computational efficiency and good robustness, and (d) accurately detects abrupt faults.

Published
2021
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41. 超长光纤干涉仪甚低频段1/f噪声影响研究

Author

Tian Shuaifei, 田帅飞, primary, Yang Jun, 杨军, additional, Yuan Yonggui, 苑勇贵, additional, Zhang Yibo, 张毅博, additional, Zhu Haibo, 祝海波, additional, An Ran, 安然, additional, Yu Zhangjun, 喻张俊, additional, Wang Yuncai, 王云才, additional, and Qin Yuwen, 秦玉文, additional

Published
2021
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44. 超长光纤干涉仪甚低频段1/f噪声影响研究

Author

田帅飞 Tian Shuaifei, 杨军 Yang Jun, 苑勇贵 Yuan Yonggui, 张毅博 Zhang Yibo, 祝海波 Zhu Haibo, 安然 An Ran, 喻张俊 Yu Zhangjun, 王云才 Wang Yuncai, and 秦玉文 Qin Yuwen

Subjects
Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials
Published
2021

48. High-resolution distributed polarization crosstalk measurement for polarization maintaining fiber with considerable dispersion

Author

Yu, Zhangjun, primary, Yang, Jun, additional, Yuan, Yonggui, additional, Li, Hanyang, additional, Hou, Changbo, additional, Hou, Chengcheng, additional, Zhang, Haoliang, additional, Tian, Shuaifei, additional, Lu, Xu, additional, Zhang, Xiaojun, additional, Jiang, Fuqiang, additional, Zhu, Zheng, additional, Zhang, Jianzhong, additional, Zhang, Yu, additional, Liu, Zhihai, additional, and Yuan, Libo, additional

Published
2018
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