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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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A Method for Reducing Ocean Wave-Induced Magnetic Noises in Shallow-Water MT Data Using a Complex Adaptive Filter

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Journal of Ocean University of China 2023年第1期22卷 99-106页

作者： WU Yunju LUO Ming LI Yuguo GE Jiaqi PAN Lindong College of Marine Geoscience and Key Laboratory of Submarine Geosciences and Prospecting TechniquesMinistry of EducationOcean University of ChinaQingdao 266100China Evaluation and Detection Technology Laboratory of Marine Mineral Resources Qingdao National Laboratory for Marine Science and TechnologyQingdao 266237China

In shallow-water areas,the marine magnetotelluric(MT)method faces a challenge in the investigation of seabed conductivity structures due to electrical and magnetic noises induced by ocean waves,which seriously contaminate MT *** waves can affect electric and magnetic fields to different *** general,their influence on magnetic fields is considerably greater than that on electric *** this paper,a complex adaptive filter is adopted to reduce wave-induced magnetic noises in the frequency *** processing results of synthetic and measured MT data indicate that the proposed method can effectively reduce wave-induced magnetic noises and provide reliable apparent resistivity and phase data.

关键词： shallow-water areas wave-induced magnetic noises complex adaptive filter MT data processing

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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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Lubrication condition monitoring of journal bearings in diesel engine based on thermoelectricity

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Friction 2024年第11期12卷 2532-2547页

作者： Yuhao LV Hao LIU Zhigang CHEN Weijie CHANG Hui ZHANG Hulin LI Shanghai Jiao Tong University Shanghai 200240China National Key Laboratory of Marine Engine Science and Technology Shanghai 201108China Shanghai Marine Diesel Engine Research Institute Shanghai 201108China Hunan Aviation Powerplant Research Institute Aero Engine Corporation of ChinaHunan 412002China

There is still a lack of effective lubrication condition monitoring methods in the field of diesel *** paper proposes a novel thermoelectric approach to divide the lubrication state of ***,the generation mechanism of thermoelectric potential on bearings is ***,both experimental and simulation studies are done,and a strong correlation between lubrication and thermoelectric potential is *** film thickness and temperature are further confirmed as significant factors influencing thermoelectric ***,the thermoelectric potential increases with ***,a small film thickness ratio(when the film thickness ratio is less than 4)will suppress the thermoelectric *** typical lubrication states of bearings are distinguished through thermoelectric potential and supported by the Stribeck curve ***,the significant influence of lubrication on the bearing is confirmed through the analysis of surface morphology and composition.

关键词： journal bearing lubrication state,thermoelectric potential condition monitoring

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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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Elastic-Wave Reverse Time Migration Random Boundary-Noise Suppression Based on CycleGAN

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Journal of Ocean University of China 2022年第4期21卷 849-860页

作者： XU Guohao HE Bingshou Key Laboratory of the Ministry of Education for Seafloor Science and Detection Technology Ocean University of ChinaQingdao 266100China Functional Laboratory of Marine Mineral Resources Evaluation and Exploration Technology Qingdao National Laboratoryof Marine Science and TechnologyQingdao 266100China

In elastic-wave reverse-time migration(ERTM),the reverse-time reconstruction of source wavefield takes advantage of the computing power of GPU,avoids its disadvantages in disk-access efficiency and reading and writing of temporary files,and realizes the synchronous extrapolation of source and receiver *** the existing source wavefield reverse-time reconstruction algorithms,the random boundary algorithm has been widely used in three-dimensional(3D)ERTM because it requires the least storage of temporary files and low-frequency disk access during reverse-time ***,the existing random boundary algorithm cannot completely destroy the coherence of the artificial boundary reflected *** random boundary reflected wavefield with a strong coherence would be enhanced in the cross-correlation image processing of reverse-time migration,resulting in noise and fictitious image in the migration results,which will reduce the signal-to-noise ratio and resolution of the migration section near the *** overcome the above issues,we present an ERTM random boundary-noise suppression method based on generative adversarial ***,we use the Resnet network to construct the generator of CycleGAN,and the discriminator is constructed by using the PatchGAN ***,we use the gradient descent methods to train the *** fix some parameters,update the other parameters,and iterate,alternate,and continuously optimize the generator and discriminator to achieve the Nash equilibrium state and obtain the best network ***,we apply this network to the process of reverse-time *** snapshot of noisy wavefield is regarded as a 2D matrix data picture,which is used for training,testing,noise suppression,and *** method can identify the reflected signal in the wavefield,suppress the noise generated by the random boundary,and achieve *** examples show that the proposed method can significantly improve the i

关键词： random boundary reverse-time migration generative adversarial network noise suppression

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Performance of large diameter steel tubes from a floating offshore wind turbine under lateral impact loads 9th

Performance of large diameter steel tubes from a floating of...

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9th International Conference on Collision and Grounding of Ships and Offshore Structures, ICCGS 2023

作者： Ren, Yongli Yu, Zhaolong Hua, Xugang Amdahl, Jørgen Chen, Zhengqing Key Laboratory for Bridge and Wind Engineering of Hunan Province College of Civil Engineering Hunan University Hunan Changsha China Department of Marine Technology Norwegian University of Science and Technology Norway Centre for Autonomous Marine Operations and Systems Norwegian University of Science and Technology Norway

ISBN: (纸本)9781032611303

Floating offshore wind turbines (FOWTs) are expected to be increasingly installed in the world to harvest wind power in deep waters. Offshore wind turbines are often located near the coasts close to the traffic lanes and are exposed to safety threats from collisions by passing and visiting ships. It is therefore of great importance to investigate the impact mechanics in ship-FOWT collisions and propose practical design methods to protect from the collision loads. This paper presents a series of experimental and numerical studies on the performance of steel tubes from a NREL 5 MW spar-type FOWT under lateral impact loads. The experiments are designed and conducted at a scale of 1:30, where a rigid indenter mounted on a pendulum system is accelerated to collide into the scaled tubes. Global motions of the impacted tubes are accounted for an equivalent single-degree-of-freedom (SDOF) model for the rigid FOWT motions. Finite element (FE) models were established in LS-DYNA software. The effects of impact velocity as a crucial factor on the performance of the tubes against impact loads were discussed. Existing theoretical solutions for the lateral indentation resistance of the tubes were compared to the experimental and numerical results. © 2024 The Author(s).

关键词： Offshore wind turbines

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Anchoring mechanical characteristics of Ductile-Expansion bolt

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International Journal of Mining Science and technology 2024年第8期34卷 1115-1134页

作者： Yu Chen Wang Liu Linchong Huang Hang Lin Yixian Wang Yanlin Zhao Cungang Lin State Key Laboratory for Tunnel Engineering Guangzhou 510275China Guangdong Research Center for Underground Space Exploitation Technology Guangdong Key Laboratory of Marine Civil EngineeringSchool of Civil EngineeringSun Yat-sen UniversityGuangzhou 510275China Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) Zhuhai 519082China School of Resources and Safety Engineering Central South UniversityChangsha 410083China School of Civil Engineering Hefei University of TechnologyHefei 230009China School of Energy and Safety Engineering Hunan University of Science and TechnologyXiangtan 411201China

The application of ductile rock bolts has been a crucial method for solving the problems of large deformations,energy absorption and stability control issues in deep rock *** study the anchoring mechanism of the key expansive structure,this paper proposes a novel type of bolt—the Ductile-Expansion bolt,and conducts research on anchoring mechanics,energy absorption characteristics,and failure modes of the *** addition,this paper defines the concept of load-volume ratio of metal rock bolts and proves the Ductile-Expansion bolt is capable of better improving the unit volume bearing capacity of the bolt ***,laboratory and field tests verify the Ductile-Expansion bolt had better anchoring effect than the traditional rebar bolt,with the expansion structure favorably enhancing the ductility and energy absorption performance of the ***,this paper microscopically analyzes the crack propagation and distribution morphology of the bolts by establishing a 3D coupled numerical model based on *** results illustrate the interface at the variable diameter of the Ductile-Expansion bolt serves as the transition zone between high and low stress *** expansion structure can impose radial compression on the medium around the bolt,which can improve the bolt anchorage performance.

关键词： Ductile-Expansion bolt Pull-out test Peak load Anchoring mechanical characteristics

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Advances and prospects of g-C_(3)N_(4) in lithium-sulfur batteries

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Nano Research Energy 2024年第4期3卷 114-131页

作者： Hong Yin Jin He Bo Xiao Miao Zhou Wei Wang Joao Cunha Zuxin Chen Zhaohui Hou Tianqi Zhang Zhipeng Yu School of Chemistry and Chemical Engineering Key Laboratory of Hunan Province for Advanced Carbon-based Functional MaterialsHunan Institute of Science and TechnologyYueyang 414006China International Iberian Nanotechnology Laboratory(INL) Av.Mestre Jose Veiga4715-330 BragaPortugal School of Semiconductor Science and Technology South China Normal UniversityFoshan 528225China Key Laboratory of Marine Chemistry Theory and Technology(Ocean University of China) Ministry of EducationQingdao 266100China

Lithium-sulfur(Li-S)batteries are regarded as one of the most promising candidates for next-generation high-energy-density storage systems due to their superior energy density,cost-effectiveness,and environmental ***,several critical challenges impede their practical application,including the shuttle effect,low conductivity,and volume *** carbon nitride(g-C_(3)N_(4)),with its unique structure and properties,offers potential advantages in catalysis,polarization inhibition,electron conductivity,and sulfurization resistance,which may address these *** review concentrates on applying g-C_(3)N_(4) material to enhance Li-S battery *** research progress on g-C_(3)N_(4) in this context is explored from two primary perspectives:the modification of g-C_(3)N_(4) itself and its compounding with other *** the modification of g-C_(3)N_(4),the focus is on defect engineering and the nanocrystallization of its *** terms of composites,the review examines the use of g-C_(3)N_(4) doped with metals,non-metals,graphene,porous carbon,and heterojunctions in electrodes and ***,this review proposes strategies for the rational design of g-C_(3)N_(4) materials to optimize their application in Li-S *** the current research progress and trends aims to provide new insights and directions for future research in the field.

关键词： graphitic carbon nitride defect engineering heteroatom doping rational design lithium-sulfur batteries

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