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In order to reduce computational redundancy, and to recognize the perturbation signals quickly and efficiently, this paper proposed a novel recognition method for Φ-OTDR system based on affinity propagation clustering. Variational mode decomposition (VMD) are utilized to accurately extract the perturbation signal characteristic information buried in the vibration signals. Moreover, in order to improve the efficiency of clustering algorithm, a novel perturbation signal selection technique was developed in this work, whose effectiveness was experimentally verified. The proposed novel recognition method is then applied to the perturbation signal detection in Φ-OTDR system. The obtained results demonstrated that the proposed method is reliable and accurately identify different perturbation categories of signals.
Shaohua Xu; Zujun Qin; Wentao Zhang; Xianming Xiong; Heng Li; Zexian Wei; Octavian Adrian Postolache; Chao Mi. A Novel Method of Recognizing Disturbance Events in Φ-OTDR Based on Affinity Propagation Clustering and Perturbation Signal Selection. IEEE Sensors Journal 2021, 21, 13272 -13282.
AMA StyleShaohua Xu, Zujun Qin, Wentao Zhang, Xianming Xiong, Heng Li, Zexian Wei, Octavian Adrian Postolache, Chao Mi. A Novel Method of Recognizing Disturbance Events in Φ-OTDR Based on Affinity Propagation Clustering and Perturbation Signal Selection. IEEE Sensors Journal. 2021; 21 (12):13272-13282.
Chicago/Turabian StyleShaohua Xu; Zujun Qin; Wentao Zhang; Xianming Xiong; Heng Li; Zexian Wei; Octavian Adrian Postolache; Chao Mi. 2021. "A Novel Method of Recognizing Disturbance Events in Φ-OTDR Based on Affinity Propagation Clustering and Perturbation Signal Selection." IEEE Sensors Journal 21, no. 12: 13272-13282.
Single-path intensity-demodulated phase-sensitive optical time-domain reflectometer ( $\varphi $ -OTDR) is susceptible to noises and random interferences, which increases the probability of missing detection of external vibrations. In the work, a dual-channel $\varphi $ -OTDR is experimentally investigated to detect pencil-break vibrations and to locate a running vehicle on a highway. For the two experiments, the double sensing channels are respective the LP 01 and LP 11 modes of a two-mode step-index fiber and two independent standard single-mode optical fibers extracted from an armored four-core cable. The Rayleigh scattering traces from the two channels are both collected and processed by the conventional differential accumulation algorithm (DAA) and standard deviation algorithm (SVA), respectively. Furthermore, a decision signal is proposed via fusing the accumulated differential signals by the DAA and the variances of the Rayleigh traces by the SVA, by which we are able to conclude whether there is a vibration signal over the sensing link. Experimental results demonstrate that our method is able to identify the vibrations caused by pencil breaks and moving vehicles, respectively, with a considerable improved reliability compared to the widely used DAA.
Zujun Qin; Jiangjiang Gao; Wangchun Zhu; Wentao Zhang. Vibration Detection Based on Multipath Information Fusion in Dual-Channel ϕ-OTDR System. IEEE Access 2021, 9, 20318 -20330.
AMA StyleZujun Qin, Jiangjiang Gao, Wangchun Zhu, Wentao Zhang. Vibration Detection Based on Multipath Information Fusion in Dual-Channel ϕ-OTDR System. IEEE Access. 2021; 9 ():20318-20330.
Chicago/Turabian StyleZujun Qin; Jiangjiang Gao; Wangchun Zhu; Wentao Zhang. 2021. "Vibration Detection Based on Multipath Information Fusion in Dual-Channel ϕ-OTDR System." IEEE Access 9, no. : 20318-20330.
As a fully distributed sensor, the phase-sensitive optical time domain reflectometer (φ-OTDR) has attracted remarkable attention in real-time vibration detection. We present a dual-channel φ-OTDR (DC-φ-OTDR), formed by two single-channel φ-OTDRs (SC-φ-OTDR), to monitor running vehicles on a highway. In the double-channel system, an improved algorithm (will be referred to as the CDM&V) is proposed to alleviate the strong dependence of vibration detection on the differential step as in the widely used conventional differential method (CDM). The DC-φ-OTDR is first tested over campus road before applying it to locate moving vehicles on the highway. For comparison purposes, both the DC-φ-OTDR and SC-φ-OTDR are used to monitor the vehicles with respective signal processing methods of the CDM and CDM&V. The experimental results at campus show that the dual-path scheme can undoubtedly reduce vibration misjudgment relative to the single one due to the very small possibility of false measurements occurred simultaneously at the same location in both channels. In signal demodulation, the CDM&V greatly relaxes the constraints on the differencing interval for identifying the vehicle-caused vibration. With a step size of 5 or lower, the CDM fails to locate the running vehicle at z=~8.5 km, but the CDM&V successfully demonstrates the feasible capability of locating the vibration. With an increase in the differential interval, both the CDM and CDM&V are able to detect the vibration signal, but with the latter showing a much better noise suppression performance and hence a larger SNR. Importantly, in comparison with the SC-φ-OTDR system, the DC-φ-OTDR exhibits a considerable enhanced SNR for the detection signal regardless of which processing algorithm (i.e., CDM, CDM&V) is used. The vehicle locations positioned by the DC-φ-OTDR are confirmed by the monitoring cameras.
Shaohua Xu; Zujun Qin; Wentao Zhang; Xianming Xiong. Monitoring Vehicles on Highway by Dual-Channel φ-OTDR. Applied Sciences 2020, 10, 1839 .
AMA StyleShaohua Xu, Zujun Qin, Wentao Zhang, Xianming Xiong. Monitoring Vehicles on Highway by Dual-Channel φ-OTDR. Applied Sciences. 2020; 10 (5):1839.
Chicago/Turabian StyleShaohua Xu; Zujun Qin; Wentao Zhang; Xianming Xiong. 2020. "Monitoring Vehicles on Highway by Dual-Channel φ-OTDR." Applied Sciences 10, no. 5: 1839.
Terahertz (THz) technologies have achieved great progress in the past few decades. Developing active devices to control the THz waves is the frontier of THz applications. In this paper, a new scheme of two-bit THz encoder is proposed. Different from the present THz modulators whose spectra at different bands are varied simultaneously, our encoder can realize the individually efficient modulation of every channel. The encoder comprises the double-sided graphene-based metamaterials, in which the graphene structures on each side are connected to the external electrodes individually. The well-designed metamaterials on the front and back sides determine the resonances at two different bands (0.20 THz and 0.33 THz) separately. Through simulating the performance of this device by changing the conductivities of the graphene on each side independently, we demonstrate two-bit encoding realized by the dual-band modulation of transmission amplitude with electronic control, and the modulation depth can reach as high as 79.6%. Our encoder can promote the development of multifunctional and integrated devices, such as frequency division multiplexers and logical circuitry, which will contribute to THz communications.
Shan Yin; Xintong Shi; Wei Huang; Wentao Zhang; Fangrong Hu; Zujun Qin; Xianming Xiong. Two-Bit Terahertz Encoder Realized by Graphene-Based Metamaterials. Electronics 2019, 8, 1528 .
AMA StyleShan Yin, Xintong Shi, Wei Huang, Wentao Zhang, Fangrong Hu, Zujun Qin, Xianming Xiong. Two-Bit Terahertz Encoder Realized by Graphene-Based Metamaterials. Electronics. 2019; 8 (12):1528.
Chicago/Turabian StyleShan Yin; Xintong Shi; Wei Huang; Wentao Zhang; Fangrong Hu; Zujun Qin; Xianming Xiong. 2019. "Two-Bit Terahertz Encoder Realized by Graphene-Based Metamaterials." Electronics 8, no. 12: 1528.
We theoretically present a method for equalizing modal gain in a six-LP-mode erbium-doped fiber amplifier by combing two sections of erbium-doped fibers (EDFs) with different doping profiles. In the two EDFs, the dopant distributions are designed to be spatially mismatched to mainly support the optical amplification of different spatial modes. The optimum fiber designs have been found by employing genetic algorithm optimization when pumped by LP11 mode, resulting in less than 1.0 dB DMG over 25 nm bandwidth in the C-band for the six-LP signal modes. In addition, tolerance study of various fiber parameters has been carried out theoretically to assess fabrication challenge in realizing a desirable amplification performance.
Shaohua Xu; Wentao Zhang; Zujun Qin. Gain equalization for a six-mode-group Er-doped fiber amplifier. Optical and Quantum Electronics 2019, 52, 20 .
AMA StyleShaohua Xu, Wentao Zhang, Zujun Qin. Gain equalization for a six-mode-group Er-doped fiber amplifier. Optical and Quantum Electronics. 2019; 52 (1):20.
Chicago/Turabian StyleShaohua Xu; Wentao Zhang; Zujun Qin. 2019. "Gain equalization for a six-mode-group Er-doped fiber amplifier." Optical and Quantum Electronics 52, no. 1: 20.