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High precision and low noise demodulation scheme using adaptive fast fourier transform for fiber-optic interferometric sensors

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Optics Express 2025年第1期33卷 817-828页

作者： Liu, Zheng Lou, Ruizhe Zhang, Lingling Feng, Lei Wang, Fuyin Yao, Qiong Wu, Weijun Xia, Ji College of Meteorology and Oceanography National University of Defense Technology Changsha410073 China Hunan Key Laboratory for Marine Detection Technology Changsha410073 China College of Information Science and Engineering Northeastern University Shenyang110819 China Hunan Institute of Advanced Technology Changsha410072 China

This paper presents an adaptive fast Fourier transform (adaptive FFT) demodulation scheme, aimed at enhancing the precision and noise suppression capability of signal processing in fiber-optic interferometric sensors. By adaptively optimizing the length of the acquired spectrum and dynamically adjusting the frequency domain resolution, the proposed scheme can precisely calculate the eigenfrequency of the reflected spectrum. Therefore, the adaptive FFT demodulation scheme can effectively enhance the extraction ability of phase quadrature demodulation signal. In comparison to traditional FFT demodulation scheme, the proposed scheme demonstrates nearly a tenfold improvement in eigenfrequency calculation accuracy. The experimental results indicate a significant improvement in the stability of the adaptive FFT demodulation scheme. The fluctuations are reduced to approximately 0.03 dB. This value is roughly equivalent to 25% of the fluctuations typically observed in traditional FFT demodulation schemes. Additionally, the adaptive FFT scheme demonstrates superior adaptability to sensors with varying optical path differences (OPDs). It maintains noise levels below -100 dB@1 kHz across sensors with different OPDs, and substantially reduces noise fluctuations compared to traditional FFT scheme. Furthermore, the proposed scheme exhibits notable advantages in crosstalk suppression for multiplexed signal demodulation. The fundamental frequency crosstalk (FFC) is reduced to below -50 dB, which is approximately 10 dB lower than that achieved by traditional FFT methods. The adaptive FFT demodulation scheme shows promising potential for applications in low noise, high precision, and dynamic signal detection within fiber-optic interferometer sensors and multiplexing arrays. © 2025 Optica Publishing Group (formerly OSA). All rights reserved.

关键词： Frequency domain analysis

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An adaptive fast fourier transform demodulation algorithm for extrinsic fiber fabry-perot sensor array crosstalk suppression

An adaptive fast fourier transform demodulation algorithm fo...

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2024 Advanced Fiber Laser Conference, AFL 2024

作者： Lou, Ruizhe Liu, Zheng Li, Congyuan Fan, SiTong Li, Dian Xia, Ji Wang, Fuyin Xiong, Shuidong Yao, Qiong College of Meteorology and Oceanography National University of Defense Technology Changsha410073 China Hunan Key Laboratory for Marine Detection Technology Changsha410073 China Hunan Institute of Advanced Technology Changsha410072 China

ISBN: (数字)9781510688889

ISBN: (纸本)9781510688872

This paper proposes an adaptive Fast Fourier Transform (FFT) demodulation algorithm based on white light interference to address the crosstalk issue in extrinsic fiber Fabry-Perot (F-P) sensor arrays. For a single F-P sensor, the signal information is primarily distributed at the corresponding eigenfrequency. When the crosstalk occurs, the reflected spectrum resulting from the superposition of multiple sensor spectra contains multiple eigenfrequencies, along with the phase information of multiple sensors. The adaptive FFT demodulation algorithm can accurately identify all the eigenfrequencies of the reflected spectrum by adaptively adjusting the sampling length of the actual collected spectrum, and then efficiently extracts the phase-orthogonal demodulation signals corresponding to different eigenfrequencies, thereby reducing the level of crosstalk and achieving precise signal demodulation. This paper takes the two-element parallel multiplexing system of fiber optic F-P sensors as the research object, discusses the crosstalk suppression mechanism of this scheme. Through numerical simulation, the relationship between crosstalk and the initial phase of the sensing system, and length of the sensor is studied. The results show that compared with traditional FFT demodulation algorithms, the proposed adaptive FFT demodulation algorithm can reduce the fundamental frequency crosstalk (FFC) by 10-15 dB, which is below -70 dB, effectively reducing the crosstalk of the sensing array and reducing the precision control requirements of cavity length. It is expected to be applied to signal demodulation of large-scale fiber F-P sensor arrays. © 2025 SPIE.

关键词： Crosstalk

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Controlled-source electromagnetic noise attenuation via a deep convolutional neural network and high-quality sounding curve screening mechanism

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Geophysics 2025年第3期90卷 WA125-WA140页

作者： Liu, Yecheng Li, Diquan Li, Jin Zhang, Xian Central South University Monitoring Ministry of Education Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Changsha China Hunan Provincial Key Laboratory of Non-ferrous Resources and Geological Hazard Detection Changsha China Central South University School of Geoscience and Info-physics Changsha China Hunan Normal University College of Information Science and Engineering Hunan Provincial Key Laboratory of Intelligent Computing and Language Information Processing Changsha China Hunan University of Finance and Economics School of Information Technology and Management Hunan Provincial Key Laboratory of Finance & Economics Big Data Science and Technology Changsha China

Strong noise is one of the biggest challenges in controlled-source electromagnetic (CSEM) exploration, which severely affects the quality of the recorded signal. We develop a novel and effective CSEM noise attenuation method that integrates a deep convolutional neural network (DCNN) with a high-quality sounding curve screening mechanism. This method first uses a DCNN to learn the large-scale noise characteristics of CSEM measured data and build a DCNN denoising model for attenuating the noise. Because some impulse noise remains after DCNN denoising, the high-quality sounding curve screening mechanism is innovatively applied to optimize the DCNN denoised data. The core of this method is the smoothness value (SV), which quantitatively evaluates the smoothness of the sounding curve (apparent resistivity curve). In effect, the mechanism segments the overall DCNN denoised data and calculates the corresponding sounding curve and its SV for each segment. The highest-quality sounding curve can be screened out by comparing the SVs of all curves as well as obtaining the highest-quality data segment present in the overall DCNN denoised data. Finally, our method is validated with synthetic and field data, demonstrating its feasibility and effectiveness in attenuating large-scale CSEM noise. The quality of CSEM data, which is heavily affected by noise, is significantly improved after processing by our method. © 2025 Society of Exploration Geophysicists. All rights reserved.

关键词： Deep neural networks

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Cooperative output regulation of heterogeneous directed multi-agent systems:a fully distributed model-free reinforcement learning framework

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Science China(Information Sciences) 2025年第2期68卷 170-185页

作者： Xiongtao SHI Yanjie LI Chenglong DU Huiping LI Chaoyang CHEN Weihua GUI Guangdong Key Laboratory of Intelligent Morphing Mechanisms and Adaptive Robotics School of Mechanical Engineering and AutomationHarbin Institute of Technology (Shenzhen) School of Automation Central South University School of Marine Science and Technology Northwestern Polytechnical University School of Information and Electrical Engineering Hunan University of Science and Technology

In this paper, the cooperative output regulation(COR) problem of a class of unknown heterogeneous multi-agent systems(MASs) with directed graphs is studied via a model-free reinforcement learning(RL) based fully distributed eventtriggered control(ETC) strategy. First, we consider the scenario that the exosystem is accessible globally to all agents, an internal model-based augmented algebraic Riccati equation(AARE) is constructed, and its solution is learned by the proposed model-free RL algorithm via online input-output data. Further, for the scenario that the exosystem is accessible only to its adjacent followers, the distributed observers are designed for each agent to get the state of the exosystem, and an internal modelbased fully distributed adaptive ETC protocol is then synthesized to construct the corresponding AARE, and the feedback gain matrix is learned in a model-free fashion. The model-free RL-based control protocol proposed in this paper can not only remove the prior knowledge of agents' dynamics, but also release the dependence on global information by the adaptive event-triggered mechanism(ETM) and the new graph-based Lyapunov function. Finally, simulation results are illustrated to show the feasibility and effectiveness of the proposed control scheme.

关键词： model-free reinforcement learning unknown heterogeneous multi-agent systems fully distributed event-triggered control directed graph

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Analysis of DOA Estimation Under Mixed-resolution Based on Conformal Arrays 16

Analysis of DOA Estimation Under Mixed-resolution Based on C...

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16th International Conference on Signal Processing Systems, ICSPS 2024

作者： Gu, Shenao Guo, Muran Key Laboratory of Advanced Marine Communication and Information Technology AVIC United Technology Center for Electromagnetic Spectrum Collaborative Detection and Intelligent cognition College of Information and Communication Engineering Harbin Engineering University Harbin150001 China

ISBN: (纸本)9781510689251

Conformal antennas typically utilize short dipoles to reduce space occupation. Conformal antenna arrays are essentially polarization-sensitive arrays with broad applicability and enhanced anti-interference capabilities. However, a practical issue that needs to be addressed is the high power consumption and resource usage resulting from high-resolution analog-to-digital converters (ADCs). In this paper, we introduce the mixed-resolution quantization method into the conformal array to alleviate the pressure on resource transmission by partially reducing the quantization resolution. The receive signal model is constructed in this paper, and a rank-deficient MUSIC algorithm suitable for the proposed scheme is developed. The direction of arrival (DOA) parameters, as well as the polarization parameters, are estimated with considerable accuracy. The power consumption and system cost are effectively reduced with a small sacrifice on parameter estimation accuracy. Numerical simulations validate the feasibility of proposed mixed-quantized conformal array. © 2025 SPIE.

关键词： Direction of arrival

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Underwater arbitrary ranging based on chirped pulse interferometry with a mode-locked laser

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Journal of Lightwave technology 2025年第11期43卷 5235-5243页

作者： Shi, Haonan Zhao, Haihan Xu, Xinyang Zhu, Zhiwei Zhai, Jingsheng Li, Xiaobo Tianjin University School of Marine Science and Technology Tianjin300072 China Research Institute of China Electronics Technology Group Corporation Science and Technology on Electro-Optical Information Security Control Laboratory No. 53 Tianjin300308 China The Chinese University of Hong Kong Department of Mechanical and Automation Engineering Hong Kong999077 Hong Kong Nanjing University of Aeronautics and Astronautics Key Laboratory of Space Photoelectric Detection and Perception Ministry of Industry and Information Technology Nanjing211106 China

Underwater distance measurement and length sensing, as fundamental functions of geoscience, are integrated into underwater robots and vessels in various forms of sensor payloads and play a crucial role in a wide range of remote sensing applications. Advanced laser-based detection systems and algorithms are essential for underwater tasks, such as detecting damage in underwater pipelines and conducting detailed structural health assessments. In this paper, we experimentally demonstrated an arbitrary underwater ranging system by the chirped pulse interferometry with a mode-locked laser. Water's inherent characteristic introduces dispersion, enabling unique distance discrimination. Adjusting the repetition frequency allows us to acquire the interference spectrum. A long fiber delay line, stabilized by the servo-controlled system, eliminates the ranging dead zone. The widest fringe of the interference spectrum, corresponding to an instantaneous repetition frequency, indicates the arbitrary measured distance. Leveraging a charge-coupled device detection module, we achieved an update rate of 13.5 Hz for the interference spectrum. Experimental results show a precise distance difference within 59.8 μm at the 5 m range underwater without the dead zone. © 2025 IEEE. All rights reserved.

关键词： Laser mode locking

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Effect of Oblique Laser Shock Peening on Fretting Fatigue of FGH95 Powder Superalloy 6

Effect of Oblique Laser Shock Peening on Fretting Fatigue of...

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2024 6th International Conference on Advanced Materials and Ecological Environment, AMEE 2024

作者： Qu, Xiangming Wang, Wenjun Zhao, Yanyun Cao, Jun Zhu, Haiyan Guo, Xiaojun Wang, Xu Zhang, Yongkang College of Mechanical Engineering Hunan Institute of Science and Technology Yueyang Hunan China Guangdong Provincial Key Laboratory of Advanced Manufacturing Technology of Marine Energy Equipment Guangdong University of Technology Guangdong Guangzhou China Foshan Yuantian Mattress Machinery Co. Ltd Guangdong Foshan China AECC Hunan Aviation Powerplant Research Institute Hunan Zhuzhou China

Due to the high-frequency vibration contact of blade tenon, the contact surface of the mortise surface of the turbine disk is prone to fretting wear and fatigue fracture. The effects of shock times of Oblique Laser Shock Peening (LSP) and temperature on the fretting fatigue properties were studied. The fretting fatigue life of Oblique LSP treated samples at room temperature could be increased by 103.0%;At high temperatures, the fretting fatigue life could be increased by 68.5%. Through the analysis of fracture morphology, the fracture developing zone of fretting fatigue and tensile fatigue samples were compared. It is revealed that the wear in the transverse contact pads would promote the initiation of fatigue cracks;Due to the compressive force of the transverse contact pads, the degree of plastic deformation of the fretting specimens would increase, the quasi-cleavage facets appeared, and the tear ridge characteristics were obvious. The results of this paper provide a reference for the Oblique LSP of the FGH95 powder superalloy turbine disk and other aero-engine parts. © Published under licence by IOP Publishing Ltd.

关键词： Fracture

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Fixed-Time Prescribed Performance Control for USV Trajectory Tracking Considering External Disturbance

Fixed-Time Prescribed Performance Control for USV Trajectory...

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International Conference on Artificial Intelligence and Autonomous Transportation, AIAT 2024

作者： Wang, Siqin Wu, Defeng You, Zheng School of Marine Engineering Jimei University Fujian Xiamen361021 China Fujian Provincial Key Laboratory of Naval Architecture and Ocean Engineering Fujian Xiamen361021 China Fujian Institute of Innovation for Marine Equipment Detection and Remanufacturing Industrial Technology Fujian Xiamen361021 China

ISBN: (纸本)9789819639762

In light of the trajectory tracking challenge for unmanned surface vehicle (USV) amidst unknown disturbances, a dynamic surface control strategy with prescribed performance has been proposed. Initially, an improved fixed-time performance function (FTPF) is constructed, and the error is equivalent transformed, which simplifies the performance constraint problem into an unconstrained problem. The function ensures that the tracking error swiftly converges to a vicinity of the origin within the designated time, and the transient performance is guaranteed. Subsequently, the dynamic surface approach is employed to avert the adverse effects of differential operations on the velocity control law. Third, a nonlinear disturbance observer is designed to deal with the external disturbance of the ocean. It can precisely estimate and counteract the disturbance term within the control law in real-time, thereby enhancing control accuracy and bolstering the system’s robustness. Finally, the simulation outcomes demonstrate that the raised approach enables the USV to swiftly follow the desired trajectory and maintain it within the prescribed limits. Through stability analysis and comparison algorithm, the superiority of this algorithm is proved. © Beijing Paike Culture Commu. Co., Ltd. 2025.

关键词： Unmanned surface vehicles

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Collision Avoidance for Unmanned Surface Vehicles Based on the PPO with DBSCAN Algorithm

Collision Avoidance for Unmanned Surface Vehicles Based on t...

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International Conference on Artificial Intelligence and Autonomous Transportation, AIAT 2024

作者： Yu, Hui Wu, Defeng Li, Guoqiang Li, Yuqin School of Marine Engineering Jimei University Fujian Xiamen361021 China Fujian Provincial Key Laboratory of Naval Architecture and Ocean Engineering Fujian Xiamen361021 China Fujian Institute of Innovation for Marine Equipment Detection and Remanufacturing Industrial Technology Fujian Xiamen361021 China

ISBN: (纸本)9789819639762

Unmanned surface vehicles (USV) have gained a significant position in ocean resource development due to their cost-effectiveness and safety. Collision avoidance is the crucial technology determining whether a USV can complete resource exploration missions. This paper proposes a novel collision avoidance algorithm incorporating designed clustering algorithm and improved deep reinforcement learning (DRL) consisting of two parts. The improved collision avoidance algorithm involves collision risk assessment based on the Density-Based Spatial Clustering of Applications with Noise (DBSCAN) Algorithm used to classify obstacle ships. Secondly, Proximal policy optimization. Finally, multi-ship collision avoidance simulation platform is established to verify the reliability of the proposed algorithm. The simulation results show the higher collision avoidance success rate than traditional algorithms. © Beijing Paike Culture Commu. Co., Ltd. 2025.

关键词： Risk assessment

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Research on Passive Direction of Arrival Estimation algorithm of Underwater Targets Based on Fiber Optic Hydrophone array 4

Research on Passive Direction of Arrival Estimation algorith...

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4th International Computational Imaging Conference, CITA 2024

作者： Yang, YaHan Hang, Dongdong Hao, GeYang Lv, XiaoPeng Yang, YuCheng Wu, GuoJun Science and Technology Service Department Qingdao Marine Science and Technology Center Qingdao266200 China Ocean Observation and Detection Department Laoshan Laboratory Qingdao266200 China Shaanxi Key Laboratory of Ocean Optics Xi'an Institute of Optics and Precision Mechanics Chinese Academy of Sciences Xi'an710119 China

ISBN: (纸本)9781510688834

To meet the demands of unmanned underwater mobile platforms, we developed a fiber optic hydrophone array that can detect weak underwater signals at a distance. We tested the performance of the hydrophone array system for passive Direction of Arrival (DOA) estimation in the Qingdao Sea area. A multiple Signal Classification Algorithm (MUSIC) was employed to estimate the direction of low-frequency narrowband signals. MUSIC demonstrated a sharper spectrum peak and a narrower main lobe beam-width compared to the Conventional Beamforming (CBF) and Minimum Variance Distortionless Response (MVDR) methods. On average, The MUSCI method can reduce the main lobe beam width by about 80% compared to the CBF and 22% compared to the MVDR. Near the 90-degree ray direction, the MUSIC can effectively overcome the Rayleigh limit and achieve super-resolution underwater passive DOA estimation. © 2025 SPIE.

关键词： Direction of arrival

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