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A feedback control method for phase signal demodulation in fber-optic hydrophones
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作者 Zhiqiang LIU Lei XIA +3 位作者 Qiangfeng LYU Bin WU Ronghua HUAN Zhilong HUANG 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2024年第3期515-528,共14页
In the realm of acoustic signal detection,the identification of weak signals,particularly in the presence of negative signal-to-noise ratios,poses a significant challenge.This challenge is further heightened when sign... In the realm of acoustic signal detection,the identification of weak signals,particularly in the presence of negative signal-to-noise ratios,poses a significant challenge.This challenge is further heightened when signals are acquired through fiber-optic hydrophones,as these signals often lack physical significance and resist clear systematic modeling.Conventional processing methods,e.g.,low-pass filter(LPF),require a thorough understanding of the effective signal bandwidth for noise reduction,and may introduce undesirable time lags.This paper introduces an innovative feedback control method with dual Kalman filters for the demodulation of phase signals with noises in fiber-optic hydrophones.A mathematical model of the closed-loop system is established to guide the design of the feedback control,aiming to achieve a balance with the input phase signal.The dual Kalman filters are instrumental in mitigating the effects of signal noise,observation noise,and control execution noise,thereby enabling precise estimation for the input phase signals.The effectiveness of this feedback control method is demonstrated through examples,showcasing the restoration of low-noise signals,negative signal-to-noise ratio signals,and multi-frequency signals.This research contributes to the technical advancement of high-performance devices,including fiber-optic hydrophones and phase-locked amplifiers. 展开更多
关键词 feedback control method fiber-optic hydrophone acoustic signal detection phase signal
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Recent Progress in Fiber-Optic Hydrophones 被引量:8
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作者 Zhou MENG Wei CHEN +3 位作者 Jianfei WANG Xiaoyang HU Mo CHEN Yichi ZHANG 《Photonic Sensors》 SCIE EI CAS CSCD 2021年第1期109-122,共14页
Fiber-optic hydrophone (FOH) is a significant type of acoustic sensor, which can be used in both military and civilian fields such as underwater target detection, oil and natural gas prospecting, and earthquake inspec... Fiber-optic hydrophone (FOH) is a significant type of acoustic sensor, which can be used in both military and civilian fields such as underwater target detection, oil and natural gas prospecting, and earthquake inspection. The recent progress of FOH is introduced from five aspects, including large-scale FOH array, very-low-frequency detection, fiber-optic vector hydrophone (FOVH), towed linear array, and deep-sea and long-haul transmission. The above five aspects indicate the future development trends in the FOH research field, and they also provide a guideline for the practical applications of FOH as well as its array. 展开更多
关键词 fiber-optic hydrophone large-scale array very-low-frequency detection fiber-optic vector hydrophone towed linear array deep sea long-haul fiber transmission
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Subsurface multi-physical characterization of mountain excavation and city construction in loess plateau with a fiber-optic sensing system 被引量:1
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作者 Jie Liu Bin Shi +3 位作者 Kai Gu Meng-Ya Sun Jun-Cheng Yao He-Ming Han 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第8期2935-2946,共12页
Mountain excavation and city construction(MECC)projects being launched in the Loess Plateau in China involve the creation of large-scale artificial land.Understanding the subsurface evolution characteristics of the ar... Mountain excavation and city construction(MECC)projects being launched in the Loess Plateau in China involve the creation of large-scale artificial land.Understanding the subsurface evolution characteristics of the artificial land is essential,yet challenging.Here,we use an improved fiber-optic monitoring system for its subsurface multi-physical characterization.The system enables us to gather spatiotemporal distribution of various parameters,including strata deformation,temperature,and moisture.Yan’an New District was selected as a case study to conduct refined in-situ monitoring through a 77 m-deep borehole and a 30 m-long trench.Findings reveal that the ground settlement involves both the deformation of the filling loess and the underlying intact loess.Notably,the filling loess exhibits a stronger creep capability compared to underlying intact loess.The deformation along the profile is unevenly distributed,with a positive correlation with soil moisture.Water accumulation has been observed at the interface between the filling loess and the underlying intact loess,leading to a significant deformation.Moreover,the temperature and moisture in the filling loess have reached a new equilibrium state,with their depths influenced by atmospheric conditions measuring at 31 m and 26 m,respectively.The refined investigation allows us to identify critical layers that matter the sustainable development of newly created urban areas,and provide improved insights into the evolution mechanisms of land creation. 展开更多
关键词 Mountain excavation and city construction fiber-optic monitoring Multi-physical characterization Compacted loess
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Fiber-Optic Sensors and Their Practical Research in the Internet of Things
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作者 Hanqing Liu 《Journal of Electronic Research and Application》 2024年第5期1-5,共5页
With the rapid development of the Internet of Things(IoT)technology,fiber-optic sensors,as a kind of high-precision and high-sensitivity measurement tool,are increasingly widely used in the field of IoT.This paper out... With the rapid development of the Internet of Things(IoT)technology,fiber-optic sensors,as a kind of high-precision and high-sensitivity measurement tool,are increasingly widely used in the field of IoT.This paper outlines the advantages of fiber-optic sensors over traditional sensors,such as high precision,strong resistance to electromagnetic interference,and long transmission distance.On this basis,the paper discusses the application scenarios of fiber-optic sensors in the Internet of Things,including environmental monitoring,intelligent industry,medical and health care,intelligent transportation,and other fields.It is hoped that this study can provide theoretical support and practical guidance for the further development of fiber-optic sensors in the field of the Internet of Things,as well as promote the innovation and application of IoT. 展开更多
关键词 fiber-optic sensor Internet of Things Practical application
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Thermal integrity profiling of cast-in-situ piles in sand using fiber-optic distributed temperature sensing 被引量:1
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作者 Jing Wang Honghu Zhu +4 位作者 Daoyuan Tan Zili Li Jie Li Chao Wei Bin Shi 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2023年第12期3244-3255,共12页
Defects in cast-in-situ piles have an adverse impact on load transfer at the pile‒soil interface and pile bearing capacity. In recent years, thermal integrity profiling (TIP) has been developed to measure temperature ... Defects in cast-in-situ piles have an adverse impact on load transfer at the pile‒soil interface and pile bearing capacity. In recent years, thermal integrity profiling (TIP) has been developed to measure temperature profiles of cast-in-situ piles, enabling the detection of structural defects or anomalies at the early stage of construction. However, using this integrity testing method to evaluate potential defects in cast-in-situ piles requires a comprehensive understanding of the mechanism of hydration heat transfer from piles to surrounding soils. In this study, small-scale model tests were conducted in laboratory to investigate the performance of TIP in detecting pile integrity. Fiber-optic distributed temperature sensing (DTS) technology was used to monitor detailed temperature variations along model piles in sand. Additionally, sensors were installed in sand to measure water content and matric suction. An interpretation method against available DTS-based thermal profiles was proposed to reveal the potential defective regions. It shows that the temperature difference between normal and defective piles is more obvious in wet sand. In addition, there is a critical zone of water migration in sand due to the water absorption behavior of cement and temperature transfer-induced water migration in the early-age concrete setting. These findings could provide important insight into the improvement of the TIP testing method for field applications. 展开更多
关键词 Geotechnical monitoring Distributed temperature sensing(DTS) Pile defect fiber-optic thermal integrity profiling(FO-TIP) Heat transfer Pile‒soil interface
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Dual-channel fiber-optic surface plasmon resonance sensor with cascaded coaxial dual-waveguide D-type structure and microsphere structure 被引量:1
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作者 李玲玲 魏勇 +4 位作者 刘春兰 任卓 周爱 刘志海 张羽 《Chinese Physics B》 SCIE EI CAS CSCD 2023年第2期201-208,共8页
To address the restriction of fiber-optic surface plasmon resonance(SPR) sensors in the field of multi-sample detection, a novel dual-channel fiber-optic SPR sensor based on the cascade of coaxial dual-waveguide D-typ... To address the restriction of fiber-optic surface plasmon resonance(SPR) sensors in the field of multi-sample detection, a novel dual-channel fiber-optic SPR sensor based on the cascade of coaxial dual-waveguide D-type structure and microsphere structure is proposed in this paper. The fiber sidepolishing technique converts the coaxial dual-waveguide fiber into a D-type one, and the evanescent wave in the ring core leaks, generating a D-type sensing region;the fiber optic fused ball push technology converts the coaxial dual waveguides into microspheres, and the stimulated cladding mode evanescent wave leaks, producing the microsphere sensing region. By injecting light into the coaxial dual-waveguide middle core alone, the sensor can realize single-stage sensing in the microsphere sensing area;it can also realize dual-channel sensing in the D-type sensing area and microsphere sensing area by injecting light into the ring core. The refractive index measurement ranges for the two channels are 1.333–1.365 and 1.375–1.405, respectively, with detection sensitivities of 981.56 nm/RIU and 4138 nm/RIU. The sensor combines wavelength division multiplexing and space division multiplexing technologies, presenting a novel research concept for multi-channel fiber SPR sensors. 展开更多
关键词 coaxial dual-waveguide optical fiber D structure optical fiber microsphere structure dual-channel fiber-optic surface plasmon resonance(SPR)sensor
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Testing an improved cymbal hydrophone
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作者 陈晟 林关成 《Journal of Marine Science and Application》 2009年第4期328-332,共5页
Cymbal hydrophones have small volume and high sensitivity, but their reception is not stable enough, and their reception is in too narrow a frequency band. In order to overcome these inadequacies, the structure of the... Cymbal hydrophones have small volume and high sensitivity, but their reception is not stable enough, and their reception is in too narrow a frequency band. In order to overcome these inadequacies, the structure of the cymbal hydrophone was improved. The single ceramic piezoelectric element was replaced with a double one, the radius of the ceramic piezoelectric element was reduced, and a parallel circuit was added. A static analysis of this new structure was developed, and then simulations were made of both the traditional and new hydrophone structure using finite element software. Tests were then conducted in a tank. The results showed that the improved hydrophone has reception in a wider frequency band, reception performance is stable within this frequency band, and sensitivity is still high. 展开更多
关键词 cymbal hydrophone sensitivity resonance frequency parallel connection frequency band
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A Bionic Fish Cilia Median-Low Frequency Three-Dimensional Piezoresistive MEMS Vector Hydrophone 被引量:6
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作者 Guo-jun Hang Zhen Li +3 位作者 Shu-juan Wu Chen-yang Xue Shi-e Yang Wen-dong Zhang 《Nano-Micro Letters》 SCIE EI CAS 2014年第2期136-142,共7页
A bionic fish cilia median-low frequency three-dimensional MEMS vector hydrophone is reported in this paper. The piezoresistive reasonable position was obtained through finite element analysis by ANSYS and the structu... A bionic fish cilia median-low frequency three-dimensional MEMS vector hydrophone is reported in this paper. The piezoresistive reasonable position was obtained through finite element analysis by ANSYS and the structure was formed by MEMS processes including lithography, ion implantation, PECVD and etching,etc. The standing wave barrel results show that the lowest sensitivity of the hydrophone is-200 d B and reach up to-160 d B(in which the voltage amplification factor is 300). It has a good frequency response characteristics in 25 Hz ~ 1500 Hz band. Directivity tests displayed that the hydrophone has a good "8"-shaped directivity,in which the resolution is not less than 30 d B, and asymmetry of the maximum axial sensitivity value is less than 1.2 d B. 展开更多
关键词 MEMS vector hydrophone BIONIC ANSYS Median-low frequency
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Ultrasonic sensitivity-improved fiber-optic Fabry-Perot interferometer using a beam collimator and its application for ultrasonic imaging of seismic physical models 被引量:3
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作者 Zhi-Hua Shao Xue-Guang Qiao +1 位作者 Feng-Yi Chen and Qiang-Zhou Rongt 《Chinese Physics B》 SCIE EI CAS CSCD 2018年第9期128-136,共9页
An ultrasonic sensitivity-improved fiber-optic Fabry-Perot interferometer (FPI) is proposed and employed for ultra- sonic imaging of seismic physical models (SPMs). The FPI comprises a flexible ultra-thin gold fil... An ultrasonic sensitivity-improved fiber-optic Fabry-Perot interferometer (FPI) is proposed and employed for ultra- sonic imaging of seismic physical models (SPMs). The FPI comprises a flexible ultra-thin gold film and the end face of a graded-index multimode fiber (MMF), both of which are enclosed in a ceramic tube. The MMF in a specified length can collimate the diverged light beam and compensate for the light loss inside the air cavity, leading to an increased spectral fringe visibility and thus a steeper spectral slope. By using the spectral sideband filtering technique, the collimated FP1 shows an improved ultrasonic response. Moreover, two-dimensional images of two SPMs are achieved in air by recon- structing the pulse-echo signals through using the time-of-flight approach. The proposed sensor with easy fabrication and compact size can be a good candidate for high-sensitivity and high-precision nondestructive testing of SPMs. 展开更多
关键词 fiber-optic sensor Fabry-Perot interferometer seismic physical model
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Monitoring the hydrolyzation of aspirin during the dissolution testing for aspirin delayed-release tablets with a fiber-optic dissolution system 被引量:4
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作者 Yan Wang Ping-Ping Xu +4 位作者 Xin-Xia Li Kun Nie Ming-Fu Tuo Bin Kong Jian Chen 《Journal of Pharmaceutical Analysis》 CAS 2012年第5期386-389,共4页
The purpose of this study was to investigate the hydrolyzation of aspirin during the process of dissolution testing for aspirin delayed-release tablets. Hydrolysis product of salicylic acid can result in adverse effec... The purpose of this study was to investigate the hydrolyzation of aspirin during the process of dissolution testing for aspirin delayed-release tablets. Hydrolysis product of salicylic acid can result in adverse effects and affect the determination of dissolution rate assaying. In this study, the technique of differential spectra was employed, which made it possible to monitor the dissolution testing in situ. The results showed that the hydrolyzation of aspirin made the percentage of salicylic acid exceed the limit of free salicylic acid (4.0), and the hydrolyzation may affect the quality detection of aspirin delayed-release tablets. 展开更多
关键词 Aspirin delayed-releasetablets Drug dissolution test fiber-optic dissolution system UV-vis spectrum
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Influence of array elements’ consistency on SNR of hydrophone array 被引量:3
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作者 ZHANG Xiao-yong SHANG Zhen-zhen +1 位作者 JI Song-xiang ZHANG Guo-jun 《Journal of Measurement Science and Instrumentation》 CAS CSCD 2019年第3期241-245,共5页
The influence of array element’s consistency on the hydrophone array’s signal-to-noise ratio (SNR) is studied. The consistency of array elements means the outputs of all the array’s elements are the same, that is t... The influence of array element’s consistency on the hydrophone array’s signal-to-noise ratio (SNR) is studied. The consistency of array elements means the outputs of all the array’s elements are the same, that is to say, the outputs have the same phase and amplitude when their inputs are the same. The relationship between the SNR and the correlation coefficient of signal and the relationship between the SNR and the correlation coefficient of noise are given. Hydrophone array’s gain with the output of elements’ inconsistent phase and amplitude is analyzed theoretically. When the signal is single-frequency, the gain expression of two-elements array is deduced. Then the gain is calculated when the phase difference is 10° and the amplitude difference is 3 dB. The theoretical analysis is verified through simulation. The simulation results show the variation rule of array’s SNR when the consistency changes: the array SNR gain is greatly affected by the consistency of the elements’ output and the gain decreases as the consistency decreases and the gain may be negative when the amplitude response becomes worse. 展开更多
关键词 hydrophone element array CONSISTENCY signal-to-noise ratio (SNR) GAIN
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Method for Measuring Self-noise of Vector Hydrophones 被引量:1
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作者 Zhi Li Hongjuan Chen 《Journal of Marine Science and Application》 CSCD 2017年第3期370-374,共5页
The Vector Hydrophone(VH) is widely used to remotely detect underwater targets. Accurately measuring the self-noise of the VH provides an important basis for evaluating the performance of the detection system in which... The Vector Hydrophone(VH) is widely used to remotely detect underwater targets. Accurately measuring the self-noise of the VH provides an important basis for evaluating the performance of the detection system in which it is utilized, since the ability to acquire weak signals is determined by the VH self-noise level. To accurately measure the VH self-noise level in actual working conditions, the Dual-channel Transfer Function Method(DTFM) is proposed to reduce ambient background noise interference. In this paper, the underlying principles of DTFM in reducing ambient background noise is analyzed. The numerical simulations to determine the influence of ambient background noise, and the sensitivity difference of the two VHs on the measurement results are studied. The results of measuring the VH self-noise level in a small laboratory water tank by using DTMF indicate that ambient background noise interference can be reduced effectively by employing DTMF, more accurate self-noise level can be obtained as well. The DTMF provides an effective method for accurately measuring the self-noise level of VHs and also provides technical support for the practical application of the VH in underwater acoustics. 展开更多
关键词 SELF-NOISE vector hydrophone acoustic measurement underwater transducer transfer function method
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Design of fiber-optic collector for spectrometer based on curved mirror 被引量:1
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作者 ZHUANG Xin-gang WANG Li-li +2 位作者 SHAO Xiu-mei FANG Jia-xiong JIANG Ben-he 《Journal of Measurement Science and Instrumentation》 CAS CSCD 2017年第1期97-102,共6页
To enlarge the detection range of traditional fiber-optic spectrometer,two rotating parabolic mirrors were first used in the design of fiber-optic collector for spectrometer,which can extend the detection range of spe... To enlarge the detection range of traditional fiber-optic spectrometer,two rotating parabolic mirrors were first used in the design of fiber-optic collector for spectrometer,which can extend the detection range of spectrometer from centimeter-scale to50m,as a super-low altitude remote sensing detector under passive lighting conditions.According to the performance requirements of fiber-spectrometer for optical collector,this study deduced the calculation formulae of design size of parabolic optical collector applied to different sensitivity spectrometers,different detection targets,different detection ranges and different weathers.Based on the calculation results,the model of fiber-optic collector with a diameter of16mm and a height of7.8mm was designed by ZEMAX.And then,TracePro,a light simulation software,was applied to ray tracing.The simulation results of optical radiation magnification agrees well with theoretical value,and the relative error is less than0.78%.This optical collector can effectively extend the detection range of spectrometer and expand its application fields and scopes.Compared with traditional refractive optical collector,it has several advantages of compact structure,low weight and low cost. 展开更多
关键词 fiber-optic collector fiber-spectrometer rotating parabolic mirror infrared radiation atmospheric transmission
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A Design of High-precision High-Voltage Fiber-Optic Analog Signal Isolation Converter 被引量:1
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作者 李建伟 许留伟 +1 位作者 刘小宁 杨雷 《Plasma Science and Technology》 SCIE EI CAS CSCD 2002年第3期1281-1287,共7页
This paper introduces a design of high-precision high-voltage fiber-optic analog sig-nal isolation converter based on the technology of Voltage-to-Frequency (V/F) and Frequency-to-Voltage (F/V) conversion. It describe... This paper introduces a design of high-precision high-voltage fiber-optic analog sig-nal isolation converter based on the technology of Voltage-to-Frequency (V/F) and Frequency-to-Voltage (F/V) conversion. It describes the principle, system configuration and hardware design. 展开更多
关键词 In DESIGN A Design of High-precision High-Voltage fiber-optic Analog Signal Isolation Converter FVC VFC
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A New Method for Matched Field Localization Based on Two-Hydrophone 被引量:2
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作者 李焜 方世良 《China Ocean Engineering》 SCIE EI CSCD 2015年第1期105-120,共16页
The conventional matched field processing (MFP) uses large vertical arrays to locate an underwater acoustic target. However, the use of large vertical arrays increases equipment and computational cost, and causes so... The conventional matched field processing (MFP) uses large vertical arrays to locate an underwater acoustic target. However, the use of large vertical arrays increases equipment and computational cost, and causes some problems such as element failures, and array tilting to degrade the localization performance. In this paper, the matched field localization method using two-hydrophone is proposed for underwater acoustic pulse signals with an unknown emitted signal waveform. Using the received signal of hydrophones and the ocean channel pulse response which can be calculated from an acoustic propagation model, the spectral matrix of the emitted signal for different source locations can be estimated by employing the method of frequency domain least squares. The resulting spectral matrix of the emitted signal for every grid region is then multiplied by the ocean channel frequency response matrix to generate the spectral matrix of replica signal. Finally, the matched field localization using two-hydrophone for underwater acoustic pulse signals of an unknown emitted signal waveform can be estimated by comparing the difference between the spectral matrixes of the received signal and the replica signal. The simulated results from a shallow water environment for broadband signals demonstrate the significant locali- zation performance of the proposed method. In addition, the localization accuracy in five different cases are analyzed by the simulation trial, and the results show that the proposed method has a sharp peak and low sidelobes, overcoming the problem of high sidelobes in the conventional MFP due to lack of the number of elements. 展开更多
关键词 two-hydrophone least squares matchedfield source localization
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Using Brillouin fiber-optic ring laser to provide base station with uplink optical carrier in a 10 GHz radio over fiber system 被引量:1
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作者 陈昊硕 林如俭 叶家骏 《Journal of Shanghai University(English Edition)》 CAS 2009年第6期450-453,共4页
In this paper, a 10 GHz radio over fiber system is analyzed. The Brillouin fiber-optic ring laser is used in the center station (CS) to suppress the optical carrier for the modulation depth enhancement. Simultaneous... In this paper, a 10 GHz radio over fiber system is analyzed. The Brillouin fiber-optic ring laser is used in the center station (CS) to suppress the optical carrier for the modulation depth enhancement. Simultaneously, the Stockes wave induced by the Brillouin amplification injects and locks the Fabry-Perot (FP) laser to output a signal-mode optical source, which works as the uplink optical carrier. 展开更多
关键词 radio over fiber (RoF) Brillouin fiber-optic ring laser Fabry-Perot (FP) laser
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Experimental Measurements of the Sensitivity of Fiber-optic Bragg Grating Sensors with a Soft Polymeric Coating under Mechanical Loading,Thermal and Magnetic under Cryogenic Conditions 被引量:2
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作者 关明智 王省哲 +2 位作者 辛灿杰 周又和 马力祯 《Chinese Physics Letters》 SCIE CAS CSCD 2015年第1期140-144,共5页
The strain and temperature sensing performance of fiber-optic Bragg gratings (FBGs) with soft polymeric coating, which can be used to sense internal strain in superconducting coils, are evaluated under variable cryo... The strain and temperature sensing performance of fiber-optic Bragg gratings (FBGs) with soft polymeric coating, which can be used to sense internal strain in superconducting coils, are evaluated under variable cryogenic field and magnetic field. The response to a temperature and strain change of coated-soft polymeric FBGs is tested by comparing with those of coated-metal FBGs. The results indicate that the coated-soft polymeric FBGs can freely detect temperature and thermal strain, their At variable magnetic field, the tested results indicate accuracy and repeatability are also discussed in detail. that the cross-coupling effects of FBGs with different matrixes are not negligible to measure electromagnetic strain during fast excitation. The present results are expected to be able to provide basis measurements on the strain of pulsed superconducting magnet/cable (cable- around-conduit conductors, cable-in-conduit conductors), independently or utilized together with other strain measurement methods. 展开更多
关键词 FBG net Experimental Measurements of the Sensitivity of fiber-optic Bragg Grating Sensors with a Soft Polymeric Coating under Mechanical Loading Thermal and Magnetic under Cryogenic Conditions
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Design and Benchmark Tests of a Multi-Channel Hydrophone Array System for Dolphin Echolocation Recordings
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作者 Josefin Starkhammar Mats Amundin +3 位作者 Johan Nilsson Tomas Jansson Monica Almqvist Hans W. Persson 《Open Journal of Acoustics》 2012年第3期121-130,共10页
This paper describes in depth the design and application considerations of a computer based measurement system enabling 1 MS/s simultaneous sampling of 47 hydrophones for cross sectional recordings of echolocation bea... This paper describes in depth the design and application considerations of a computer based measurement system enabling 1 MS/s simultaneous sampling of 47 hydrophones for cross sectional recordings of echolocation beams of toothed whales (Odontocetes). An earlier prototype version of the system has previously only been presented as a brief proof of principle that did not offer a complete description of the software and hardware solution. Crucial hardware and software design considerations of the further developed system include the re-arm times of the burst mode sampling and the dual-core distributed execution of the software components. The rearm time was measured to 283 μs, using a 550 μs long sample window around each click. This enables burst mode sampling of clicks with an inter-click interval as short as 833 μs. It is shown through both synthetic benchmark tests of the system and through field measurements of bottlenose dolphins (Tursiops truncatus) and a beluga whale (Delphinapterus leucas) that it is capable of acquiring, analyzing and visualizing data in run-time. It operates effectively also in highly reverberant surroundings like concrete pools and shallow waters. Burst mode sampling allows the system to block reflections with 0.3 - 0.5 m longer propagation paths than the direct path. It is suggested that the system’s compliance to reverberant recording sites makes it valuable in future dolphin echolocation studies. 展开更多
关键词 DOLPHIN ECHOLOCATION Measurement SYSTEM hydrophone Array BURST Mode Sampling
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Review of Fiber-optic Distributed Acoustic Sensing Technology 被引量:2
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作者 Zhicheng ZHONG Kuiyuan LIU +1 位作者 Xue HAN Jun LIN 《Instrumentation》 2019年第4期47-58,共12页
A distributed optical-fiber acoustic sensor is an acoustic sensor that uses the optical fiber itself as a photosensitive medium,and is based on Rayleigh backscattering in an optical fiber.The sensor is widely used in ... A distributed optical-fiber acoustic sensor is an acoustic sensor that uses the optical fiber itself as a photosensitive medium,and is based on Rayleigh backscattering in an optical fiber.The sensor is widely used in the safety monitoring of oil and gas pipelines,the classification of weak acoustic signals,defense,seismic prospecting,and other fields.In the field of seismic prospecting,distributed optical-fiber acoustic sensing(DAS)will gradually replace the use of the traditional geophone.The present paper mainly expounds the recent application of DAS,and summarizes recent research achievements of DAS in resource exploration,intrusion monitoring,pattern recognition,and other fields and various DAS system structures.It is found that the high-sensitivity and long-distance sensing capabilities of DAS play a role in the extensive monitoring applications of DAS in engineering.The future application and development of DAS technology are examined,with the hope of promoting the wider application of the DAS technology,which benefits engineering and society. 展开更多
关键词 fiber-optic Distributed Acoustic Sensor Rayleigh Backscatter GEOPHONE Φ-optical Time-domain Reflectometry
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An Improved Cymbal Hydrophone Made of Lanthanum-Modified Lead Zirconate Titanite
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作者 陈晟 孙超 《Journal of Southwest Jiaotong University(English Edition)》 2009年第2期148-152,共5页
Lanthanum-modified lead zirconate titanite (PLZT) piezoelectric ceramics has higher piezoelectric and dielectric properties compared with the common lead zirconate titanite (PZT) ceramics. These properties endue t... Lanthanum-modified lead zirconate titanite (PLZT) piezoelectric ceramics has higher piezoelectric and dielectric properties compared with the common lead zirconate titanite (PZT) ceramics. These properties endue the cymbal hydrophones made of PLZT usually with stable performance but lower receiving sensitivity. In order to improve the sensitivity, through a static analysis on hydrophone we did some changes for the PLZT hydrophone by reducing the radius of the piezoelectric ceramics and sealing its boundary. Furthermore, ANSYS simulations were made, and the experiments for the improved PLZT hydrophone and the original one were carried out in water pool. The results show that the receiving sensitivity of the improved cymbal hydrophone made of PLZT is 3 -4 dB higher than that of the original, and that the frequency response still keeps flat within 18 kHz band. 展开更多
关键词 Lanthanum-modified lead zirconate titanite (PLZT) Cymbal hydrophone Sensitivity
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