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Distributed fiber optic sensors for tunnel monitoring:A state-of-the-art review
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作者 Xuehui Zhang Honghu Zhu +1 位作者 Xi Jiang Wout Broere 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第9期3841-3863,共23页
Distributed fiber optic sensors(DFOSs)possess the capability to measure strain and temperature variations over long distances,demonstrating outstanding potential for monitoring underground infrastructure.This study pr... Distributed fiber optic sensors(DFOSs)possess the capability to measure strain and temperature variations over long distances,demonstrating outstanding potential for monitoring underground infrastructure.This study presents a state-of-the-art review of the DFOS applications for monitoring and assessing the deformation behavior of typical tunnel infrastructure,including bored tunnels,conventional tunnels,as well as immersed and cut-and-cover tunnels.DFOS systems based on Brillouin and Rayleigh scattering principles are both considered.When implementing DFOS monitoring,the fiber optic cable can be primarily installed along transverse and longitudinal directions to(1)measure distributed strains by continuously adhering the fiber to the structure’s surface or embedding it in the lining,or(2)measure point displacements by spot-anchoring it on the lining surface.There are four critical aspects of DFOS monitoring,including proper selection of the sensing fiber,selection of the measuring principle for the specific application,design of an effective sensor layout,and establishment of robust field sensor instrumentation.These four issues are comprehensively discussed,and practical suggestions are provided for the implementation of DFOS in tunnel infrastructure monitoring. 展开更多
关键词 Distributed fiber optic sensor(DFOS) Tunnel infrastructure Distributed strain sensing Point displacement monitoring Field instrumentation
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A Fiber Optic Sensor for the Simultaneous Measurement of Dual-parameter Based on Hydrogel-immobilized Enzyme Complex
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作者 TONG Yilin ZHANG Yu +2 位作者 HAN Xuecai YU Kan BAO Jiaqi 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS CSCD 2023年第6期1311-1318,共8页
A novel fiber optic sensor based on hydrogel-immobilized enzyme complex was developed for the simultaneous measurement of dual-parameter,the leap from a single parameter detecting fiber optic sensor to a fiber optic s... A novel fiber optic sensor based on hydrogel-immobilized enzyme complex was developed for the simultaneous measurement of dual-parameter,the leap from a single parameter detecting fiber optic sensor to a fiber optic sensor that can continuously detect two kinds of parameters was achieved.By controlling the temperature from high to low,the function of fiber sulfide sensor and fiber DCP sensor can be realized,so as to realize the continuous detection of dual-parameter.The different variables affecting the sensor performance were evaluated and optimized.Under the optimal conditions,the response curves,linear detection ranges,detection limits and response times of the dual-parameter sensor for testing sulfide and DCP were obtained,respectively.The sensor displays high selectivity,good repeatability and stability,which have good potentials in analyzing sulfide and DCP concentration of practical water samples. 展开更多
关键词 hydrogel-immobilized enzyme complex dual-parameter simultaneous measurement fiber optic sensor
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Modeling, Simulation and Experimental Studies of Refractometric Fiber Optic Sensor
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作者 Supriya S. Patil Arvind D. Shaligram 《Journal of Sensor Technology》 CAS 2023年第1期1-11,共11页
Refractometric fiber optic sensors have a number of applications in industry due to advantages like remote sensing ability, compact size, easy to fit, etc. A refractometric sensor contains a pair of parallel fibers an... Refractometric fiber optic sensors have a number of applications in industry due to advantages like remote sensing ability, compact size, easy to fit, etc. A refractometric sensor contains a pair of parallel fibers and a gap between the sensor probe and reflector, wherein the liquid whose refractive index is to be measured is filled. This paper describes the importance of mathematical modeling of this sensor. Ray tracing approach is used to model the sensor mathematically. This mathematical model is generalized for any scenario which is useful to avoid tedious trial and error techniques to design the sensor prototype. Mathematical modelling is a useful tool to optimize the gap distance for a detection of refractive index of liquid. The model is developed and analyzed rigorously considering adulteration of diesel by kerosene where refractive index varies from 1.44 to 1.46. Simulation experiments are carried out to optimize the gap distance which is found to be 6.8 mm using both models. Experiments are carried out where sensor probe is fabricated and results are analyzed. It is observed that for suggested gap distance sensor output varies almost linear over the entire range. 展开更多
关键词 Refractometric fiber optic sensor Mathematical Modeling Ray Tracing Technique
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A bellow pressure fiber optic sensor for static ice pressure measurements 被引量:2
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作者 崔丽琴 龙欣 秦建敏 《Applied Geophysics》 SCIE CSCD 2015年第2期255-262,276,共9页
Static ice pressure affects safe operation of hydraulic structures. However, current detection methods are hindered by the following limitations: poor real-time performance and errors owing to the partial pressure of... Static ice pressure affects safe operation of hydraulic structures. However, current detection methods are hindered by the following limitations: poor real-time performance and errors owing to the partial pressure of the surrounding wall on traditional electrical resistance strain bellow pressure sensors. We developed a fiber optic sensor with a special pressure bellow to monitor the static ice pressure on hydraulic structures and used the sensor to measure static pressure in laboratory ice growth and melting tests from -30℃ to 5℃. The sensor resolution is 0.02 kPa and its sensitivity is 2.74 × 10-4/kPa. The experiments suggest that the static ice pressure peaks twice during ice growth and melting. The first peak appears when the ice temperature drops to -15℃ owing to the liquid water to solid ice transition. The second peak appears at 0℃ owing to the thermal expansion of the ice during ice melting. The novel fiber optic sensor exhibits stable performance, high resolution, and high sensitivity and it can be used to monitor the static ice pressure during ice growth and melting. 展开更多
关键词 Static ice pressure pressure bellow fiber optic sensor improved Y-type fiber bundle
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PLASMA RESONANCE FIBER OPTIC SENSOR FOR CURE MONITORING OF EPOXY COMPOSITE
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作者 邱浩 梁大开 +1 位作者 张焕春 经亚枝 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 2001年第2期182-187,共6页
The plasma resonance fiber optic sensor has a research values in theory and is widely used in engineering because of its simple structure and high sensitivity. It is a simple and sensitive method to measure the refrac... The plasma resonance fiber optic sensor has a research values in theory and is widely used in engineering because of its simple structure and high sensitivity. It is a simple and sensitive method to measure the refractive index with optical fiber plasma wave. We make use of this characteristic to manufacture the plasma resonance fiber optic sensor which can detect the cure of epoxy compo site. We study the method of testing the solutions which have different refractive index with plasma resonance fiber optic sensor. A fiber optic sensing probe which has reliable performance and convenient operation for detecting the refractive index has been designed. The system for detecting the solution refractive index is developed and used to measure the refractive index of epoxy during the different phases in the cure process. Result shows that this system is credible and stable, the parameters tested are in accord with the facts. 展开更多
关键词 plasma wave fiber optic sensor refractive index EPOXY cure detecting
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A Fiber Optic Sensor for 2,4-dichlorophenol Analysis based on Optical Composite Oxygen-sensitive Film 被引量:3
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作者 TONG Yilin ZENG Zhihong +2 位作者 YU Kan BAO Jiaqi YIN Juanjuan 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2020年第4期743-749,共7页
A novel fiber optic sensor based on optical composite oxygen-sensitive film was developed for determination of 2,4-dichlorophenol(DCP).The optical composite oxygen-sensitive film consists of tris(2,2’-bipyridyl)dichl... A novel fiber optic sensor based on optical composite oxygen-sensitive film was developed for determination of 2,4-dichlorophenol(DCP).The optical composite oxygen-sensitive film consists of tris(2,2’-bipyridyl)dichloro ruthenium(II)hexahydrate(Ru(bpy)3Cl2)as the fluorescence indicator and iron(III)tetrasulfophthalocyanine(Fe(III)PcTs)as bionic enzyme.A lock-in amplifier was used for detecting the lifetime of the composite oxygen-sensitive film by measuring the phase delay of the sensor head.The different variables affecting the sensor performance were evaluated and optimized.Under the optimal conditions(i e,pH 6.0,25℃,Fe(III)PcTs concentration of 5.0×10^-5 mol/L),the linear detection range,detection limit and response time of the fiber optic sensor are 3.0×10^-7-9.0×10^-5 mol/L,4.8×10^-8 mol/L(S/N=3),and 220 s,respectively.The sensor displays high selectivity,good repeatability and stability,which have good potentials in analyzing DCP concentration in practical water samples. 展开更多
关键词 2 4-dichlorophenol optical composite oxygen-sensitive film fiber optic sensor phase delay
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A Fiber Optic Sensor for Determination of 2,4-dichlorophenol based on Iron(Ⅱ) Phthalocyanine Catalysis 被引量:2
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作者 王永红 TONG Yilin +4 位作者 黄俊 LI Kun LIU Huichao DING Liyun LI Mingtian 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2015年第6期1317-1320,共4页
A new fi ber optic sensor based on the oxidation of 2,4-dichlorophenol(DCP) catalyzed by iron(II) phthalocyanine(Fe(II)Pc) was developed for the determination of DCP. The optical oxygen sensing fi lm containin... A new fi ber optic sensor based on the oxidation of 2,4-dichlorophenol(DCP) catalyzed by iron(II) phthalocyanine(Fe(II)Pc) was developed for the determination of DCP. The optical oxygen sensing fi lm containing fl uorescence indicator Ru(bpy)3Cl2 was used to detect the consumption of oxygen in solution. Moreover, a lock-in amplifier was used to determine the lifetime of the sensor head by detecting its phase delay change. The results reveal that the sensor has a linear detection range of 1.0×10^-6- 9.0×10^-5 mol/L and a response time of 5 min. The sensor also has high selectivity, good repeatability and stability. It can be used effectively to determine DCP concentration in real samples. 展开更多
关键词 2 4-dichlorophenol iron(II) phthalocyanine phase delay change fiber optic sensor stability
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Review of reflective fiber optic sensors for surface topography measurement
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作者 YANG Rui-feng HU Chen-hao +2 位作者 GUO Chen-xia GAI Ting LANG Guo-wei 《Journal of Measurement Science and Instrumentation》 CAS CSCD 2018年第1期59-67,共9页
Different from the traditional contact surface topography measurement,reflective intensity-modulated fiber optic sensor(RIM-FOS)has the unique advantages of non-contact nondestructive detection.This paper briefly intr... Different from the traditional contact surface topography measurement,reflective intensity-modulated fiber optic sensor(RIM-FOS)has the unique advantages of non-contact nondestructive detection.This paper briefly introduces the principle and performance of RIM-FOS for surface topography measurement and compares with several other methods of topography measurement.Based on the review of its development process,this paper summarizes and analyses the hot issues of RIM-FOS in the surface topography measurement,then predicts the future trend for a guidance of the further study. 展开更多
关键词 reflective intensity-modulated fiber optic sensor(RIM-FOS) topography measurement probe structure interference compensation
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Application of Fiber Optic Sensor Technology in Intelligent Steel Strand
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作者 GUANLi LIUYu-qin 《Semiconductor Photonics and Technology》 CAS 2000年第1期48-53,共6页
A twisted fiber optic sensor based on intensity modulation is described. The principle and structure of the sensor and the choice of steel strand modules are introduced. The sensor is used to determine the tensile str... A twisted fiber optic sensor based on intensity modulation is described. The principle and structure of the sensor and the choice of steel strand modules are introduced. The sensor is used to determine the tensile strain and distribution. The experimental results show that the change of the transferring light power has an approximate linear relation with the outer force. The intelligent steel strands with this kind of sensor will have a good application in monitoring the concrete crack and deformation distribution in huge structures such as dams and bridges. 展开更多
关键词 fiber optic sensor Intelligent steel strands STRAIN
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A Fiber Optic Sensor for 2-cholrophenol Analysis based on Oxygen Sensing System
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作者 贡晶晶 HUANG Xinting +3 位作者 HUANG Jun DING Liyun LI Kun YUAN Yinquan 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2014年第6期1178-1182,共5页
A fiber optic 2-cholrophenol(2-CP) sensor was developed based on the fluorescence quenching of molecular oxygen on the oxygen-sensitive membrane and O2 consumption during catalytic oxidation reaction of 2-CP. The 2-... A fiber optic 2-cholrophenol(2-CP) sensor was developed based on the fluorescence quenching of molecular oxygen on the oxygen-sensitive membrane and O2 consumption during catalytic oxidation reaction of 2-CP. The 2-CP concentration can be determined by utilizing a lock-in amplifier to measure the change in the fluorescence lifetime of an oxygen-sensitive membrane, in which the tris(2,2′-bipyridyl) ruthenium(II) chloride complexes(Ru(II)(byp)3Cl2) were immobilized in cellulose acetate(CA) via simple hybridized approach. The experimental results show the good linear relationship between the phase delay of sensitive membrane and 2-CP concentration in its detection range of 1×10-7 to 1×10-5 mol/L and 1×10-5 to 1×10-4 mol/L. The detection limit of the sensor is 7×10-8 mol/L(S/N=3) and the response time is 5 min. Our experimental measurements confirmed good response characteristics of the as-prepared fiber optic 2-CP sensor, as well as its capability to detect the 2-CP concentration in practical water samples. 展开更多
关键词 fiber optic sensor 2-chlorophenol oxygen-sensitive membrane fluorescence quenching
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Experimental Study of Monitoring and Controlling of Composite Cure Process in Autoclave Featured with Fiber Optic Sensor
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作者 Boming ZHANG, Zhanjun WU , Dianfu WANG and Shanyi DU Center for composite, Harbin Institute of Technology Harbin 150001, China 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2001年第4期449-452,共4页
With the aid of the latest fiber optic sensing technology parameters in the cure process of ther- mosetting resin-matrix composite, such as temperature, viscosity,void and residual stress, can be monitored entirely an... With the aid of the latest fiber optic sensing technology parameters in the cure process of ther- mosetting resin-matrix composite, such as temperature, viscosity,void and residual stress, can be monitored entirely and efficiently.In this paper, experiment results of viscosity measurement in composite cure process in autoclave using fiber optic sensors are presented. Based on the sensed information, a computer program is utilized to control the cure process. With this technology, the cure process becomes more apparent and controllable, which will greatly improve the cured products and reduce the cost. 展开更多
关键词 Experimental Study of Monitoring and Controlling of Composite Cure Process in Autoclave Featured with fiber optic sensor
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Strain measurement of fiber optic sensor surface bonding on host material 被引量:2
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作者 Shiuh-Chuan HER Chang-Yu TSAI 《中国有色金属学会会刊:英文版》 CSCD 2009年第B09期143-149,共7页
Fiber optic sensor has been widely used as a structural health monitoring device by either embedding into or surface bonding onto the structures. The strain of optic fiber induced by the host material is strongly depe... Fiber optic sensor has been widely used as a structural health monitoring device by either embedding into or surface bonding onto the structures. The strain of optic fiber induced by the host material is strongly dependent on the bonding characteristics which include the protective coating, adhesive layer and the length of bonding. The strains between the fiber optics and host structure are not exact the same. The existence of the protective coating and adhesive layer would affect the strain measured by the surface bonding optic sensor. The analytical expression of the strain in the optic fiber induced by the host material was presented. The results were validated by the finite element method. The theoretical predictions reveal that the strain in the optical fiber is lower than the strain of host material. Parametric study shows that a long bonding length and high modulus of protective coating would increase the percentage of strain transferring into the optical fiber. Experiments were conducted by using Mach-Zehnder interferometer to measure the strain of the surface bonding optic fiber induced by the host structure. Good agreements were observed in comparison with the experimental results and theoretical predictions. 展开更多
关键词 光纤传感器 主机结构 应变测量 粘接材料 表面 结构健康监测 粘结长度 光纤应变
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Refractometric Fiber Optic Sensor for Detecting Salinity of Water
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作者 Supriya S. Patil Arvind D. Shaligram 《Journal of Sensor Technology》 2013年第3期70-74,共5页
Salinity is an important property of industrial and natural waters. It is defined as the measure of the mass of dissolved salts in a given mass of solution. High salinity has an impact on people and industries reliant... Salinity is an important property of industrial and natural waters. It is defined as the measure of the mass of dissolved salts in a given mass of solution. High salinity has an impact on people and industries reliant on water. High levels of salt can reduce crop yields, limit the choice of crops that can be grown and, at higher concentrations over long periods, can kill trees and make the land unsuitable for agricultural purposes. Salinity increases the “hardness” of water, which can mean more soap and detergents have to be used or water softeners installed and maintained. This can also cause scaling in pipes and heaters. The experimental determination of the salt content by drying and weighing presents some difficulties due to the loss of some components. The only reliable way to determine the true or absolute salinity of natural water is to make a complete chemical analysis. However, the method is time consuming and cannot yield the precision necessity for accurate work. Thus to determine salinity, one normally used method involves the measurement of a physical property such as conductivity, density or refractive index. The paper reports the refractometric fiber optic sensor for detection of salinity of water. The mathematical model is developed for detection of the refractive index of liquid and simulated in MATLAB. The fiber optic sensor probe is developed to measure the refractive index of the solution containing different amount of salt dissolved in water i.e. different molar concentrations. Experiments are carried out using the developed probe for these solutions. Experimental results are showing good agreement with the simulated results. 展开更多
关键词 fiber optic Chemical sensor Hardness of WATER REFRACTOMETRY Retro-Reflective Type fiber optic sensor SALINITY of WATER
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Quantitative Identification of Delamination Damage in Composite Structure Based on Distributed Optical Fiber Sensors and Model Updating
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作者 Hao Xu Jing Wang +3 位作者 Rubin Zhu Alfred Strauss Maosen Cao Zhanjun Wu 《Structural Durability & Health Monitoring》 EI 2024年第6期785-803,共19页
Delamination is a prevalent type of damage in composite laminate structures.Its accumulation degrades structural performance and threatens the safety and integrity of aircraft.This study presents a method for the quan... Delamination is a prevalent type of damage in composite laminate structures.Its accumulation degrades structural performance and threatens the safety and integrity of aircraft.This study presents a method for the quantitative identification of delamination identification in composite materials,leveraging distributed optical fiber sensors and a model updating approach.Initially,a numerical analysis is performed to establish a parameterized finite element model of the composite plate.Then,this model subsequently generates a database of strain responses corresponding to damage of varying sizes and locations.The radial basis function neural network surrogate model is then constructed based on the numerical simulation results and strain responses captured from the distributed fiber optic sensors.Finally,a multi-island genetic algorithm is employed for global optimization to identify the size and location of the damage.The efficacy of the proposed method is validated through numerical examples and experiment studies,examining the correlations between damage location,damage size,and strain responses.The findings confirm that the model updating technique,in conjunction with distributed fiber optic sensors,can precisely identify delamination in composite structures. 展开更多
关键词 Composite structures fiber optic sensor damage identification model updating surrogate model
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Functional Optical Fiber Sensors Detecting Imperceptible Physical/Chemical Changes for Smart Batteries
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作者 Yiding Li Li Wang +3 位作者 Youzhi Song Wenwei Wang Cheng Lin Xiangming He 《Nano-Micro Letters》 SCIE EI CAS CSCD 2024年第8期268-308,共41页
The battery technology progress has been a contradictory process in which performance improvement and hidden risks coexist.Now the battery is still a“black box”,thus requiring a deep understanding of its internal st... The battery technology progress has been a contradictory process in which performance improvement and hidden risks coexist.Now the battery is still a“black box”,thus requiring a deep understanding of its internal state.The battery should“sense its internal physical/chemical conditions”,which puts strict requirements on embedded sensing parts.This paper summarizes the application of advanced optical fiber sensors in lithium-ion batteries and energy storage technologies that may be mass deployed,focuses on the insights of advanced optical fiber sensors into the processes of one-dimensional nano-micro-level battery material structural phase transition,electrolyte degradation,electrode-electrolyte interface dynamics to three-dimensional macro-safety evolution.The paper contributes to understanding how to use optical fiber sensors to achieve“real”and“embedded”monitoring.Through the inherent advantages of the advanced optical fiber sensor,it helps clarify the battery internal state and reaction mechanism,aiding in the establishment of more detailed models.These advancements can promote the development of smart batteries,with significant importance lying in essentially promoting the improvement of system consistency.Furthermore,with the help of smart batteries in the future,the importance of consistency can be weakened or even eliminated.The application of advanced optical fiber sensors helps comprehensively improve the battery quality,reliability,and life. 展开更多
关键词 Smart battery Advanced embedded optical fiber sensor Battery internal physical/chemical state Quality-reliability-life characteristic
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An Optical Fiber Sensor for Simultaneous Measurement of pO2 and pH
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作者 Baorong Fu Xianwen Zhang +1 位作者 Huimin Cao Zhushanying Zhang 《Open Journal of Applied Sciences》 CAS 2023年第4期579-590,共12页
Whether in the monitoring of critically ill patients such as shock, respiratory failure, brain injury, or in major anesthesia surgeries, it is necessary to evaluate the patient’s pO<sub>2</sub> and pH. An... Whether in the monitoring of critically ill patients such as shock, respiratory failure, brain injury, or in major anesthesia surgeries, it is necessary to evaluate the patient’s pO<sub>2</sub> and pH. An optical fiber sensor presented is capable of monitoring the presence of oxygen partial pressure (pO<sub>2</sub>) and pH in the real-time. The sensor is based on fluorescence sensing of polymer immobilized in the oxygen/pH-sensitive membranes and covalently attached to the optical fiber probe. The design of this sensor uses LED as light source, which is an excitation light source, inducing specific wavelengths of fluorescence on the oxygen/pH-sensitive membrane. The intensity and lifetime of fluorescence are related to the pO<sub>2</sub> and pH. So the pO<sub>2</sub> and pH can be measured by the relationship between the pO<sub>2</sub>/pH values and the intensity and lifetime of fluorescence. The signal conditioning system based on DSP and STM32 was used to store and process data, and display test values. The response of the sensor for pO<sub>2</sub> and pH monitoring with nitrogen (N<sub>2</sub>) as a balancing gas in the laboratory was performed. Finally, the oxygen/pH sensing scheme presented in this work is intended for using in biological, medical and environmental applications. 展开更多
关键词 optical fiber sensor OXYGEN PH FLUORESCENCE
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Research Progress in the Key Device and Technology for Fiber Optic Sensor Network 被引量:2
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作者 Deming LIU Qizhen SUN Ping LU Li XIA Chaotan SIMA 《Photonic Sensors》 SCIE EI CAS CSCD 2016年第1期1-25,共25页
The recent research progress in the key device and technology of the fiber optic sensor network (FOSN) is introduced in this paper. An architecture of the sensor optical passive network (SPON), by employing hybrid... The recent research progress in the key device and technology of the fiber optic sensor network (FOSN) is introduced in this paper. An architecture of the sensor optical passive network (SPON), by employing hybrid wavelength division multiplexing/time division multiplexing (WDM/TDM) techniques similar to the fiber communication passive optical network (PON), is proposed. The network topology scheme of a hybrid TDM/WDM/FDM (frequency division multiplexing) three-dimension fiber optic sensing system for achieving ultra-large capacity, long distance, and high resolution sensing performance is performed and analyzed. As the most important device of the FOSN, several kinds of light source are developed, including the wideband multi-wavelength fiber laser operating at C band, switchable and tunable 2 μm multi-wavelength fiber lasers, ultra-fast mode-locked fiber laser, as well as the optical wideband chaos source, which have very good application prospects in the FOSN. Meanwhile, intelligent management techniques for the FOSN including wideband spectrum demodulation of the sensing signals and real-time fault monitoring of fiber links are presented. Moreover, several typical applications of the FOSN are also discussed, such as the fiber optic gas sensing network, fiber optic acoustic sensing network, and strain/dynamic strain sensing network. 展开更多
关键词 fiber optic sensor network fiber optic sensor laser intelligent management fiber optic gas sensing fiber optic acoustic sensing fiber optics strain sensing
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Real-Time Distributed Fiber Optic Sensor for Security Systems: Performance, Event Classification and Nuisance Mitigation 被引量:36
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作者 Seedahmed S. MAHMOUD Yuvaraja VISAGATHILAGAR Jim KATSIFOLIS 《Photonic Sensors》 SCIE EI CAS 2012年第3期225-236,共12页
The success of any perimeter intrusion detection system depends on three important performance parameters: the probability of detection (POD), the nuisance alarm rate (NAR), and the false alarm rate (FAR). The ... The success of any perimeter intrusion detection system depends on three important performance parameters: the probability of detection (POD), the nuisance alarm rate (NAR), and the false alarm rate (FAR). The most fundamental parameter, POD, is normally related to a number of factors such as the event of interest, the sensitivity of the sensor, the installation quality of the system, and the reliability of the sensing equipment. The suppression of nuisance alarms without degrading sensitivity in fiber optic intrusion detection systems is key to maintaining acceptable performance. Signal processing algorithms that maintain the POD and eliminate nuisance alarms are crucial for achieving this. In this paper, a robust event classification system using supervised neural networks together with a level crossings (LCs) based feature extraction algorithm is presented for the detection and recognition of intrusion and non-intrusion events in a fence-based fiber-optic intrusion detection system. A level crossings algorithm is also used with a dynamic threshold to suppress torrential rain-induced nuisance alarms in a fence system. Results show that rain-induced nuisance alarms can be suppressed for rainfall rates in excess of 100mm/hr with the simultaneous detection of intrusion events. The use of a level crossing based detection and novel classification algorithm is also presented for a buried pipeline fiber optic intrusion detection system for the suppression of nuisance events and discrimination of intrusion events. The sensor employed for both types of systems is a distributed bidirectional fiber-optic Mach-Zehnder (MZ) interferometer. 展开更多
关键词 Adaptive level crossings fiber optic sensor intrusion detection nuisance alarm
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A fiber optic sensor for detecting and monitoring cracks in concrete structures 被引量:11
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作者 BAO TengFei WANG JiaLin YAO Yuan 《Science China(Technological Sciences)》 SCIE EI CAS 2010年第11期3045-3050,共6页
The formation and propagation of cracks reflect the aging and pathologic changes of concrete structures and may cause problems such as seepage and long-term durability. Crack detection and monitoring is therefore an e... The formation and propagation of cracks reflect the aging and pathologic changes of concrete structures and may cause problems such as seepage and long-term durability. Crack detection and monitoring is therefore an effective way to evaluate structural health conditions. An important challenge in such a task is that the locations and orientations of cracks in concrete structures are difficult to predict due to material inhomogeneity and complexity. The number of the required conventional electric and electromagnetic sensors to cover all possible cracks may be too large to be practical for a monitoring scheme. In this paper, a fiber optic sensor with distributed crack sensing capability based on optical time domain reflectometry is proposed and its sensing principle is introduced. Experiments are conducted to obtain the optical power loss versus crack opening at different fiber inclination angles, and then a model is developed to quantify it. Finally, an experiment is performed to demonstrate the practical application of the sensor. The test results show that detecting and monitoring cracks with the sensor do not require a-priori knowledge of crack locations and orientations. 展开更多
关键词 fiber optic sensor CRACK CONCRETE
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On-Line Defect Detection of Aluminum Coating Using Fiber Optic Sensor 被引量:3
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作者 Supriya S. PATIL A. D. SHALIGRAM 《Photonic Sensors》 SCIE EI CAS CSCD 2015年第1期72-78,共7页
Aluminum metallization using the sprayed coating for exhaust mild steel (MS) pipes of tractors is a standard practice for avoiding rusting. Patches of thin metal coats are prone to rusting and are thus considered as... Aluminum metallization using the sprayed coating for exhaust mild steel (MS) pipes of tractors is a standard practice for avoiding rusting. Patches of thin metal coats are prone to rusting and are thus considered as defects in the surface coating. This paper reports a novel configuration of the fiber optic sensor for on-line checking the aluminum metaUization uniformity and hence for defect detection. An optimally chosen high bright 440 nm BLUE LED (light-emitting diode) launches light into a transmitting fiber inclined at the angle of 60° to the surface under inspection placed adequately. The reflected light is transported by a receiving fiber to a blue enhanced photo detector. The metallization thickness on the coated surface results in visually observable variation in the gray shades. The coated pipe is spirally inspected by a combination of linear and rotary motions. The sensor output is the signal conditioned and monitored with RISHUBH DAS. Experimental results show the good repeatability in the defect detection and coating non-uniformity measurement. 展开更多
关键词 fiber optic sensors on-line defect detection aluminum coating corrosion resistance color detection exhaust pipes of vehicles
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