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Fast-Response Fiber-Optic FPI Temperature Sensing System Based on Modulated Grating Y-Branch Tunable Laser

Photonic Sensors 2024年第1期14卷 59-72页

作者： Yang CHEUNG Zhenguo JING Qiang LIU Ang LI Yueying LIU Yihang GUO Sen ZHANG Dapeng ZHOU Wei PENG School of Physics Dalian University of TechnologyDalian 116024China School of Optoelectronic Engineering and Instrumentation Science Dalian University of TechnologyDalian 116024China School of Computer and Electronic Information/School of Artificial Intelligence Nanjing Normal UniversityNanjing 210023China

In this paper,a cost-effective and miniaturized instrument is proposed,which is based on a tunable modulated grating Y-branch(MG-Y)laser for rapid temperature measurement using a Fabry-Perot interferometer(FPI)*** FPI sensor with a 1463-μm cavity length is a short segment of a capillary tube sandwiched by two sections of single-mode fibers(SMFs).This system has a broad tunable range(1527 nm-1567 nm)with a wavelength interval of 8 pm and a tuning rate of 100 *** sensing experiments are carried out to investigate the performance of the system by demodulating the absolute cavity length of the FPI sensor using a cross-correlation *** results show that the sensor can reach the response time as short as 94 ms with the sensitivity of 802 pm/*** from the homemade and integrated essential electrical circuits,the entire system has the small size,low cost,and practical application potential to be used in the harsh environment for rapid temperature measurement.

关键词： MG-Y laser interrogator rapid temperature measurement cross-correlation algorithm

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Wide Range and High-Precision 1PPS Time Interval Measurement Method

Wide Range and High-Precision 1PPS Time Interval Measurement...

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2023 Joint Conference of the European Frequency and Time Forum and IEEE International Frequency Control Symposium, EFTF/IFCS 2023

作者： Ruilin, Zhang Zhiqi, Li Haifeng, Wang Jian, Chang Zhixin, Cao Xiangyang, Wei Zhe, Tan School of Mechano-Electronic Engineering Xidian University Xi'an China Beijing Institute of Radio Metrology and Measurement Science and Technology on Metrology and Calibration Laboratory Beijing China

ISBN: (纸本)9798350311426

High precision time interval measurement between two 1PPS signals is important in timekeeping. In time interval measurement between two 1PPS, the method of using the surface acoustic wave filter (SWAF) as the time-interpolator and calculating the time interval through the cross-correlation algorithm has high resolution and accuracy. However, the narrow pulses generated by the event start and end edges excite the SAWF. The response of SAWF has a duration of 200ns. Time intervals smaller than the response duration cannot be measured. The cross-correlation method also limits the measurement speed. In this paper, FPGA is used as the delay module to delay two 1PPS signals respectively. By measuring the time interval between each 1PPS signal and their delay signals respectively, the measurement dead zone is avoided. The calculation time is saved by gradually reducing the number of interpolation steps. Two 1PPS from the hydrogen maser were measured at room temperature and the results showed that the RMS error of this work is higher than 4.5ps and the resolution is higher than 2ps for the time interval of two 1PPS signals when the ADC is 14bit. © 2023 IEEE.

关键词： cross-correlation algorithm sample reconstruction time interpolation time interval measurement

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Research on co-phasing detection of segmented mirror based on convolutioned neural networks

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OPTICS AND LASER TECHNOLOGY 2023年第1期167卷

作者： Li, Bin Yang, Akun Li, Yanbing Sun, Zhaoxiang Wu, Jian Chen, Nan Chen, Mo East China Jiaotong Univ Intelligent Electromech Equipment Innovat Res Inst Nanchang 330013 Peoples R China Xinyu Univ Sch New Energy Sci & Engn Xinyu 338004 Peoples R China Chinese Acad Sci Inst Opt & Elect Chengdu 610209 Peoples R China

To build a greater than 10 m aperture telescope, it is necessary to use the technique of segmented mirror. Although segmented mirror enables the construction of very large aperture telescopes, they also require fine cophasing of the sub-mirrors in order to achieve the imaging capability of the whole mirror with the same aperture. As a result, there is urgently necessary to develop a large range, high precision, and fast co-phasing errors measurement technique. In this paper, a new method of two-wavelength co-phasing detection based on convolutional neural network is proposed to address the problem of slow detection speeds and low accuracy in the detection of large-range co-phasing errors (piston) by the current two-wavelength co-phasing detection method based on the cross-correlation algorithm. Firstly, the co-phasing detection dataset with piston detection range [-10.5 & mu;m, 10.5 & mu;m] at wavelengths of 737 nm and 750 nm was analyzed by theory and simulation, and the rapidity and accuracy of the method of two-wavelength co-phasing detection based on convolutional neural network were verified by this dataset, and the accuracy of the training set was greater than 99.9% and the RMS value of the test sample error was 9.8 nm. This paper further discusses the tolerances for eccentricity and gap errors required for using the neural network detection method. When the gap error or eccentricity error is less than 0.2, the piston error can be directly detected using the convolutional neural network.

关键词： Segmented mirror Co-phasing errors Convolutional neural network cross-correlation algorithm

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Adaptive large-scale particle image velocimetry method for physical model experiments of flood propagation with complex flow patterns

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MEASUREMENT 2022年 198卷

作者： Hou, Jingming Yang, Lu Wang, Xinhong Chai, Jie Zhang, Zongxiao Li, Xuan Shao, Jianbin Du, Ying'en Bai, Ganggang Xian Univ Technol State Key Lab Ecohydraul Northwest Arid Reg China Xian 710048 Shaanxi Peoples R China Northwest A&F Univ Yangling 712100 Shaanxi Peoples R China

This work presents an Adaptive Large Scale Particle Image Velocimetry method (ALSPIV), which measures surface velocity of a physical model experiment with complex flow pattern. In the experiment, the eleven low-cost, high-resolution surveillance cameras are adopted to achieve a large-scale flow field in real time. The lenses of them are shined perpendicularly on water surface to minimize perspective distortion. A camera calibration method is also designed to enhance measurement accuracy. In addition, an adaptive cross-correlation algorithm can contribute to cross-correlation and a lower signal-to-noise ratio. Finally, an experimental method is employed to verify the ALSPIV method's accuracy, and the surface velocity distributions under three different steady flows are measured to demonstrate its applicability. Results show that the method is demonstrated to be a low-cost and automatic flow diagnostic tool and an accurate means of measuring surface velocities in the physical model experiments of flood propagation with complex flow patterns.

关键词： ALSPIV Complex flow patterns cross-correlation algorithm Physical model experiment Surface velocity measurement

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Optimization in PIV algorithm for visualizing vortices in bubble wake

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FLOW MEASUREMENT AND INSTRUMENTATION 2022年 86卷

作者： Ye, Xinwei Niu, Xiaojing Tsinghua Univ Dept Hydraul Engn State Key Lab Hydrosci & Engn Beijing Peoples R China Tsinghua Univ Dept Hydraul Engn Beijing 100084 Peoples R China

The PIV (Particle image velocimetry) is the most commonly used method for flow field observation because of its high efficiency and non-interference to the flow field. This study aims to clarify the optimal parameter conditions used in the cross-correlation algorithm of PIV for flow fields with vortices. The influence factors on the error of the cross-correlation algorithm are analyzed and discussed using a synthetic flow field, including the seeding conditions, the velocity gradient and vortex size. It is confirmed that the minimum particle number density per interrogation window is about 10, which generally limits the minimum size of the window. For a vortex, when the vortex size is fixed, the velocity gradient corresponding to the characteristic velocity both controls the lower and upper limitation of window size. For a relatively small vortex, generally a window not larger than the vortex size is asked. Then, a strategy to improve the observation based on the existing equipment is discussed and applied to visualize a rising bubble wake based on LIF (Laser-induced fluorescence) images.

关键词： PIV cross-correlation algorithm Vortex Error analysis Bubble

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A New Method of Eddy Current Impedance-Extracting and Hardness-Classifying for Valves

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IEEE ACCESS 2020年 8卷 46781-46794页

作者： Hu Pengfei Xie Qingsheng Huang Haisong Guizhou Univ Minist Educ Key Lab Adv Mfg Technol Guiyang 550025 Peoples R China Guizhou Prov Inst Metro Log Testing Guiyang 550003 Peoples R China

This paper describes a new method of eddy current impedance extraction and hardness classification for valves, which is used in online classification. A finite element simulation is conducted to estimate the base magnetic response in specimens with various initial permeabilities, and a scatter diagram between the hardness calibration and initial permeability is plotted experimentally;thus, the hardness classification model is obtained by using the initial permeability as the intermediate variable. A lock-in amplifier is commonly used to measure the amplitudes of impedance components in conventional eddy current testing. This study replaces the lock-in amplifier with a cross-correlation algorithm with the objective of integrating the impedance processing with the subsequent classification. Moreover, an incremental and decremental support vector machine is used to classify the valve specimens based on the extracted impedance due to its demonstrated excellent performance for both linearly separable and nonlinearly indivisible problems. The cross-correlation algorithm and the incremental and decremental support vector machine are implemented on a field-programmable gate array, which has the advantage of parallel processing and can satisfy the online requirements. A comparison with the traditional impedance comparison method shows that the proposed method not only is suitable for online hardness classification but also achieves good performance in correlating impedance amplitude changes caused by a temperature increase of the coil and various heat treatment conditions with the hardness values.

关键词： Eddy current testing finite element model cross-correlation algorithm incremental and decremental support vector machine impedance extraction hardness classification

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Hyperspectral image-based analysis of thermal damage for ex-vivo bovine liver utilizing radiofrequency ablation

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SURGICAL ONCOLOGY-OXFORD 2021年 38卷 101564-101564页

作者： Aref, Mohamed Hisham Aboughaleb, Ibrahim H. Youssef, Abou-Bakr M. El-Sharkawy, Yasser H. Mil Tech Coll Biomed Engn Dept Cairo Egypt Cairo Univ Syst & Biomed Engn Dept Giza Egypt

Background & objective: Thermal ablation is the predominant methodology to treat liver tumors for segregating patients who are not permitted to have surgical intervention. However, noticing or predicting the size of the thermal strategies is a challenging endeavor. We aim to analyze the effects of ablation district volume following radiofrequency ablation (RFA) of ex-vivo liver exploiting a custom Hyperspectral Imaging (HSI) system. Materials and methods: RFA was conducted on the ex-vivo bovine liver at focal and peripheral blood vessel sites and observed by Custom HSI system, which has been designed to assess the exactness and proficiency using visible and near-infrared wavelengths region for tissue thermal effect. The experiment comprised up to ten trials with RFA. The experiment was carried out in two stages to assess the percentage of the thermal effect on the investigated sample superficially and for the side penetration effect. Measuring the diffuse reflectance (R , d) of the sample to identify the spectral reflectance shift which could differentiate between normal and ablated tissue exploiting the designed cross-correlation algorithm for monitoring of thermal ablation. Results: Determination of the diffuse reflection (R , d) spectral signature responses from normal, thermal effected, and thermal ablation regions of the investigated liver sample. Where the ideal wavelength range at (600-640 nm) could discriminate between these different regions. Then, exploited the converted RGB image of the HS liver tissue after RFA for more validations which shows that the optimum wavelength for differentiation at (530-560 nm and 600-640 nm). Finally, applying statistical analysis to validate our results presenting that wavelength 600 nm had the highest standard deviation (delta) to differentiate between various thermally affected regions regarding the normal tissue and wavelength 640 nm shows the highest (delta) to differentiate between the ablated and normal regions. Concl

关键词： Liver tumor Hyperspectral imaging Radiofrequency thermal Ablation cross-correlation algorithm Liver tissue thermal Effect Spectral signature

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Study on the co-phasing simulation and experimental of segmented mirror based on broadband light

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Optica Acta: International Journal of Optics 2024年第1-3期71卷

作者： Bin Li Yinling Liu Akun Yang Nan Chen Jian Wu Mo Chen a Intelligent Electromechanical Equipment Innovation Research Institute of East China Jiao-tong University Nanchang People’s Republic of China b Institute of Optics and Electronics Chinese Academy of Sciences Chengdu People’s Republic of China

At present, the co-phasing detection algorithms for segmented mirrors struggle to balance the measurement range and accuracy. This paper proposes a coarse co-phasing measurement method using the incoherent properties of a broadband (400–800 nm) light source combined with the incoherence of two semicircular diffraction patterns of visible light as a template to detect the piston error, and a narrowband algorithm for fine co-phasing measurement. The diversity factors between template patterns and actual diffraction patterns can be calculated by the cross-correlation algorithm. This proposed method addresses long measurement time caused by low target flow rate and is characterized by wide measurement range, high precision and high energy utilization. The method is theoretically researched and simulated and an experimental system which was constructed to verify the effectiveness of this method achieves 15 nm detection accuracy, and the measurement range using the proposed method can match the measurement range of the actuator.

关键词： Segmented mirrors cross-correlation algorithm phase detection broadband light

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Quantitative characterization of the interfacial roughness and thickness of inhomogeneous coatings based on ultrasonic reflection coefficient phase spectrum

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NDT & E INTERNATIONAL 2019年 102卷 16-25页

作者： Ma, Zhiyuan Luo, Zhongbing Lin, Li Krishnaswamy, Sridhar Lei, Mingkai Dalian Univ Technol NDT & E Lab Dalian 116024 Peoples R China Northwestern Univ Ctr Smart Struct & Mat Evanston IL 60208 USA Dalian Univ Technol Sch Mat Sci & Engn Surface Engn Lab Dalian 116024 Peoples R China

Aim at nondestructively characterizing the interfacial roughness of coatings, ultrasonic reflection coefficient phase spectrum (URCPS) as a function of interfacial roughness is derived based on the phase screen approximation theory [1]. For inhomogeneous coatings, the attenuation coefficient alpha(f) shows a non-negligible effect on the URCPS. The relationship of alpha(f) on frequency f is used to decouple the URCPS. The constructed URCPS is used to determine the interfacial roughness and thickness of specimens through a two-parameter inversion utilizing the cross-correlation algorithm. The effects of the coating inhomogeneity (such as porosity) on the roughness measurement are analyzed through numerical calculation. A series of simulations with interfacial roughness from 6.2 to 12.7 mu m indicate that measurement errors of the thickness are all less than 8.0%. The relative errors of the measured roughness of models without porosity and models with the porosity of 3% are less than 11.8%. For the models with porosity 5%, when the roughness is larger than 10.3 mu m, the relative error is still larger than 11.7%. Ultrasonic experiments were carried out on a tungsten carbide (WC-Ni) coating utilizing water immersion, flat transducer. The WC-Ni coating, with unknown interfacial roughness, was sprayed on a stainless steel using the high-velocity oxygen fuel (HVOF) method. Experimental results show that the interfacial roughness of specimen obtained by the proposed ultrasonic measurement are in good agreement with that of SEM observations, the absolute error of the measured roughness is less than 1.4 mu m and the relative error was less than 11.0%.

关键词： Ultrasonic Phase spectrum WC-Ni coating Interfacial roughness cross-correlation algorithm

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Identification of the Velocity, Thickness, and Interfacial Roughness of Coating Using Full Time-Domain URCPS: cross-correlation-Based Inverse Problem

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JOURNAL OF NONDESTRUCTIVE EVALUATION, DIAGNOSTICS AND PROGNOSTICS OF ENGINEERING SYSTEMS 2019年第1期2卷 011008页

作者： Ma, Zhiyuan Lin, Li Jin, Shijie Lei, Mingkai Dalian Univ Technol NDT&E Lab Dalian 116024 Peoples R China Dalian Univ Technol Sch Mat Sci & Engn Surface Engn Lab Dalian 116024 Peoples R China

Aiming at characterizing interfacial roughness of thin coatings with unknown sound velocity and thickness, we derive a full time-domain ultrasonic reflection coefficient phase spectrum (URCPS) as a function of interfacial roughness based on the phase screen approximation theory. The constructed URCPS is used to determine the velocity, thickness, and interfacial roughness of specimens through the cross-correlation algorithm. The effect of detection frequency on the roughness measurement is investigated through the finite element method. A series of simulations were implemented on Ni-coating specimens with a thickness of 400 mu m and interfacial roughness of 1.9-39.8 mu m. Simulation results indicated that the measurement errors of interfacial roughness were less than 10% when the roughness satisfies the relationship of Rq = 1.6-10.0%lambda. The measured velocity and thicknesses were in good agreement with those imported in simulation models with less than 9.3% error. Ultrasonic experiments were carried out on two Ni-coating specimens through a flat transducer with an optimized frequency of 15 MHz. Compared with the velocities measured by time-of-flight (TOF) method, the relative errors of inversed velocities were all less than 10%. The inversed thicknesses were in good agreement with those observed by optical microscopy with less than 10.9% and 7.6% error. The averaged interfacial roughness determined by the ultrasonic inversion method was 16.9 mu m and 30.7 mu m, respectively. The relative errors were 5.1% and 2.0% between ultrasonic and confocal laser scanning microscope (CLSM) method, respectively.

关键词： ultrasonic phase spectrum interfacial roughness inverse problem cross-correlation algorithm

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