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
In this paper an optically-powered optical fiber sensor for pressure measurement is introduced.Differential strain gauges of diffused silicon are employed as sensing elements and a micro-power-consumption circuit is u...In this paper an optically-powered optical fiber sensor for pressure measurement is introduced.Differential strain gauges of diffused silicon are employed as sensing elements and a micro-power-consumption circuit is used in the probe.Pulse width modulation and pulse position modulation are adopted for signal processing.展开更多
A practical optical fiber differential pressure sensor is presented at first. Then the techniques of light source feedback, set up of reference channel, proportional measurement and other methods to improve the stabil...A practical optical fiber differential pressure sensor is presented at first. Then the techniques of light source feedback, set up of reference channel, proportional measurement and other methods to improve the stability of the system as well as to reduce the interference with same nature are emphatically discussed. Finally, the experiment results of the developed instrument are given.展开更多
The ratio measurement by means of the sensing optical fiber and the reference fiber with different beginning positions, and the technique to improve the stability of the sensor are first described. Then the ability to...The ratio measurement by means of the sensing optical fiber and the reference fiber with different beginning positions, and the technique to improve the stability of the sensor are first described. Then the ability to restrain and compensate the interference of the same nature through the double channel ratio measurement is illustrated. Finally, the performance of sensor and its engineering design are discussed.展开更多
An optically powered sensor for measuring pressure which is linked by optical fiber is developed in new scheme. Its pulse position modulation (PPM) optical signal and optical supply power for electronics in probe are...An optically powered sensor for measuring pressure which is linked by optical fiber is developed in new scheme. Its pulse position modulation (PPM) optical signal and optical supply power for electronics in probe are transmitted via a single optical fiber. The optical power is carried by a 1 300 nm laser diode (LD) and the sensing data are carried by a 850 nm LED. The remote probe uses all CMOS chips and particular modulations (PPM and PWM). Its electrical consumption including signal manipulation and LED driven current from optically converted is less than 100 μW. The laser diode supplies 5 mW optical power into the fiber. A photodetector converts sufficiently this power into electrical power to drive the whole probe operation. The optically powered distance gets up to 500 m. The novel sensor combines optical fiber and electronics technology into a system. Because of using the principle of ratio measurement between measured and reference signals, as well as light feedback,the system is available with high reliable, outstanding accuracy and repeatability.展开更多
An optical fiber pressure sensor has been developed for the measurement in human body.The sensing element is possessed of a membrane structure,which is fabricated by micromachining.The fabrication process includes ani...An optical fiber pressure sensor has been developed for the measurement in human body.The sensing element is possessed of a membrane structure,which is fabricated by micromachining.The fabrication process includes anisotropic wet etching on the silicon wafer.For the transmitting source and signal light,a multimode optical fiber 50/125 μm (core/clad)in diameter was used.The intensity of the light reflected back into the fiber varies with the membrane deflection,which is s function of pressure.The deflection of the membrane by applied pressure can be mathematically described.展开更多
In order to detect the refractive index of liquid with high precision,based on modular interference,Mach-Zehnder optical fiber refractive rate sensor was studied.Sensor structure is composed of ordinary single-mode fi...In order to detect the refractive index of liquid with high precision,based on modular interference,Mach-Zehnder optical fiber refractive rate sensor was studied.Sensor structure is composed of ordinary single-mode fiber and multimode fiber,according to the singlemode multimode singlemode sequence to fuse together,and the fused optical fiber is used to process the taper.As a result,the diameter of the sensing head is about 10μm.Experimental results show that,as liquid refractive index increases range from 1.33 to 1.35,the loss peak of the transmission spectrum will shift to long wave direction.展开更多
In recent years, advanced composite structures are used extensively in many industries such as aerospace, aircraft, automobile, pipeline and civil engineering. Reliability and safety are crucial requirements posed by ...In recent years, advanced composite structures are used extensively in many industries such as aerospace, aircraft, automobile, pipeline and civil engineering. Reliability and safety are crucial requirements posed by them to the advanced composite structures be- cause of their harsh working conditions. Therefore, as a very important measure, structural health monitoring （SHM） in-service is deft- nitely demanded for ensuring their safe working in-situ. In this paper, fiber Bragg grating （FBG） sensors are surface-mounted on the hoop and in the axial directions of a FRP pressure vessel to monitor the strain status during its pressurization. The experimental results show that the FBG sensors could be used to monitor the strain development and determine the ultimate failure strain of the composite pressure vessel.展开更多
The pressure distribution in an arcing chamber is critically important for the SF6 puffer circuit breaker design. In this paper, the pressure variation of four locations in the nozzle was measured by piezoresistive an...The pressure distribution in an arcing chamber is critically important for the SF6 puffer circuit breaker design. In this paper, the pressure variation of four locations in the nozzle was measured by piezoresistive and fiber optical pressure sensors at two current levels of 10 kA and 50 kA. An arc voltage measurement was also taken. The results demonstrate that using either type of sensor with a connecting tube is able to detect the fast pressure variation in circuit breakers, however the possible distortion and delay to the pressure transient caused by the tube need further study.展开更多
A nonlinearity-compensation-free optical frequency domain reflectometry(OFDR)scheme is proposed and experimentally demonstrated based on the electrically-controlled optical frequency sweep.In the proposed scheme,the l...A nonlinearity-compensation-free optical frequency domain reflectometry(OFDR)scheme is proposed and experimentally demonstrated based on the electrically-controlled optical frequency sweep.In the proposed scheme,the linear frequency sweep light is generated by propagating an ultra-narrow-linewidth continuous-wave(CW)light through an electro-optic frequency shifter which consists of a dual-parallel Mach-Zehnder modulator(DPMZM)and an electronic 90°hybrid,where the electro-optic frequency shifter is driven by a linear frequency modulated signal generated by a direct digital synthesizer(DDS).Experimental results show that the spatial resolution and signal-to-noise ratio(SNR)of the proposed OFDR scheme without the nonlinear phase compensation are comparable to those of OFDR employing a commercial tunable laser source(TLS),an auxiliary interferometer,and a software-based nonlinear phase compensation method.The proposed OFDR scheme is helpful to reduce the complexity of the optical structure and eliminate the difficulty of developing the nonlinear phase compensation algorithm.展开更多
The accurate evaluation of pore pressure and injected volume is crucial for the laboratory characterization of hydromechanical responses of rock fractures. This study reports a series of laboratory experiments to syst...The accurate evaluation of pore pressure and injected volume is crucial for the laboratory characterization of hydromechanical responses of rock fractures. This study reports a series of laboratory experiments to systematically demonstrate the effects of external temperature and dead volume on laboratory measurements of pore pressure and injected volume in a rock fracture. We characterize the hydraulic aperture of the fracture as a function of effective normal stress using the exponential aperture model.This model is then employed to predict the pore pressure change and injected volume in the fracture without the influences of external temperature and dead volume. The external temperature changes in the cyclic loading test due to the Joule-Thompson effect for fluids. The effect of external temperature on pore pressure change in the fracture can be well explained by thermal pressurization of fluids. Our results also show that the external dead volume can significantly lower the pore pressure change in the fracture during the cyclic loading test under undrained conditions. The injected volume can also be substantially enlarged due to the external dead volume in a typical pore pressure system. Internal measurement of the pore pressure in the fracture using a fiber optic sensor cannot exclude the influences of external temperature and dead volume, primarily because of the good hydraulic communication between the fracture and pore pressure system. This study suggests that the effects of external temperature and dead volume on pore pressure response and injected volume should be evaluated for accurate laboratory characterization and inter-laboratory comparison.展开更多
Based on thinned fiber Bragg grating and polymer material, we propose a novel high-sensitivity pressure sensor and obtained a new contribution to the pressure sensitivity, which is dependent on the derivative of the e...Based on thinned fiber Bragg grating and polymer material, we propose a novel high-sensitivity pressure sensor and obtained a new contribution to the pressure sensitivity, which is dependent on the derivative of the effective refractive index （RI） of core mode with respect to the surrounding medium RI, as well as on the relationship between the polymer RI and the pressure; moreover, it is inversely proportional to Young＇s modulus of the polymer material. For the polymer with Young＇s modulus of 1.0 MPa, the total pressure sensitivity 1.54×10-2 MPa-1 can be obtained.展开更多
A new type optical fiber sensor--Tip timing Sensor is introduced in this paper. It is mostly used in vibration measurement of turbine blade, which can realize real-time and non-contact measurement.
基金supported by the National Natural Science Foundation of China(No.51279122)the Graduate Innovation Foundation of Taiyuan University of Technology(No.2013A019)
文摘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.
文摘In this paper an optically-powered optical fiber sensor for pressure measurement is introduced.Differential strain gauges of diffused silicon are employed as sensing elements and a micro-power-consumption circuit is used in the probe.Pulse width modulation and pulse position modulation are adopted for signal processing.
文摘A practical optical fiber differential pressure sensor is presented at first. Then the techniques of light source feedback, set up of reference channel, proportional measurement and other methods to improve the stability of the system as well as to reduce the interference with same nature are emphatically discussed. Finally, the experiment results of the developed instrument are given.
文摘The ratio measurement by means of the sensing optical fiber and the reference fiber with different beginning positions, and the technique to improve the stability of the sensor are first described. Then the ability to restrain and compensate the interference of the same nature through the double channel ratio measurement is illustrated. Finally, the performance of sensor and its engineering design are discussed.
文摘An optically powered sensor for measuring pressure which is linked by optical fiber is developed in new scheme. Its pulse position modulation (PPM) optical signal and optical supply power for electronics in probe are transmitted via a single optical fiber. The optical power is carried by a 1 300 nm laser diode (LD) and the sensing data are carried by a 850 nm LED. The remote probe uses all CMOS chips and particular modulations (PPM and PWM). Its electrical consumption including signal manipulation and LED driven current from optically converted is less than 100 μW. The laser diode supplies 5 mW optical power into the fiber. A photodetector converts sufficiently this power into electrical power to drive the whole probe operation. The optically powered distance gets up to 500 m. The novel sensor combines optical fiber and electronics technology into a system. Because of using the principle of ratio measurement between measured and reference signals, as well as light feedback,the system is available with high reliable, outstanding accuracy and repeatability.
基金supported by National Science Foundation of the U.S.,under fund cite NSF 03-512supported by National‘863 Project'of China,under fund cite A05106AA5114.
文摘An optical fiber pressure sensor has been developed for the measurement in human body.The sensing element is possessed of a membrane structure,which is fabricated by micromachining.The fabrication process includes anisotropic wet etching on the silicon wafer.For the transmitting source and signal light,a multimode optical fiber 50/125 μm (core/clad)in diameter was used.The intensity of the light reflected back into the fiber varies with the membrane deflection,which is s function of pressure.The deflection of the membrane by applied pressure can be mathematically described.
基金National Natural Science Foundation of China(No.61405127)Shanxi Province Science Foundation for Youths(No.2014021023-1)+1 种基金Scientific and Technologial Innovation Programs of Higher Education Institutions in Shanxi ProvinceProgram for Top Young Academic Leaders of Higher Learning Institutions in Shanxi Province
文摘In order to detect the refractive index of liquid with high precision,based on modular interference,Mach-Zehnder optical fiber refractive rate sensor was studied.Sensor structure is composed of ordinary single-mode fiber and multimode fiber,according to the singlemode multimode singlemode sequence to fuse together,and the fused optical fiber is used to process the taper.As a result,the diameter of the sensing head is about 10μm.Experimental results show that,as liquid refractive index increases range from 1.33 to 1.35,the loss peak of the transmission spectrum will shift to long wave direction.
文摘In recent years, advanced composite structures are used extensively in many industries such as aerospace, aircraft, automobile, pipeline and civil engineering. Reliability and safety are crucial requirements posed by them to the advanced composite structures be- cause of their harsh working conditions. Therefore, as a very important measure, structural health monitoring （SHM） in-service is deft- nitely demanded for ensuring their safe working in-situ. In this paper, fiber Bragg grating （FBG） sensors are surface-mounted on the hoop and in the axial directions of a FRP pressure vessel to monitor the strain status during its pressurization. The experimental results show that the FBG sensors could be used to monitor the strain development and determine the ultimate failure strain of the composite pressure vessel.
文摘The pressure distribution in an arcing chamber is critically important for the SF6 puffer circuit breaker design. In this paper, the pressure variation of four locations in the nozzle was measured by piezoresistive and fiber optical pressure sensors at two current levels of 10 kA and 50 kA. An arc voltage measurement was also taken. The results demonstrate that using either type of sensor with a connecting tube is able to detect the fast pressure variation in circuit breakers, however the possible distortion and delay to the pressure transient caused by the tube need further study.
基金the National Natural Science Foundation of China under Grants No.61927821 and No.61575037.
文摘A nonlinearity-compensation-free optical frequency domain reflectometry(OFDR)scheme is proposed and experimentally demonstrated based on the electrically-controlled optical frequency sweep.In the proposed scheme,the linear frequency sweep light is generated by propagating an ultra-narrow-linewidth continuous-wave(CW)light through an electro-optic frequency shifter which consists of a dual-parallel Mach-Zehnder modulator(DPMZM)and an electronic 90°hybrid,where the electro-optic frequency shifter is driven by a linear frequency modulated signal generated by a direct digital synthesizer(DDS).Experimental results show that the spatial resolution and signal-to-noise ratio(SNR)of the proposed OFDR scheme without the nonlinear phase compensation are comparable to those of OFDR employing a commercial tunable laser source(TLS),an auxiliary interferometer,and a software-based nonlinear phase compensation method.The proposed OFDR scheme is helpful to reduce the complexity of the optical structure and eliminate the difficulty of developing the nonlinear phase compensation algorithm.
基金supported by the Research Fund of the State Key Laboratory of Coal Resources and Safe Mining,China University of Mining and Technology,China (Grant No. SKLCRSM21KF002)supported by the Initiative and Networking Fund of Helmholtz Association (Germany) for the Helmholtz Young Investigator Group ARES (Contract No. VH-NG-1516)。
文摘The accurate evaluation of pore pressure and injected volume is crucial for the laboratory characterization of hydromechanical responses of rock fractures. This study reports a series of laboratory experiments to systematically demonstrate the effects of external temperature and dead volume on laboratory measurements of pore pressure and injected volume in a rock fracture. We characterize the hydraulic aperture of the fracture as a function of effective normal stress using the exponential aperture model.This model is then employed to predict the pore pressure change and injected volume in the fracture without the influences of external temperature and dead volume. The external temperature changes in the cyclic loading test due to the Joule-Thompson effect for fluids. The effect of external temperature on pore pressure change in the fracture can be well explained by thermal pressurization of fluids. Our results also show that the external dead volume can significantly lower the pore pressure change in the fracture during the cyclic loading test under undrained conditions. The injected volume can also be substantially enlarged due to the external dead volume in a typical pore pressure system. Internal measurement of the pore pressure in the fracture using a fiber optic sensor cannot exclude the influences of external temperature and dead volume, primarily because of the good hydraulic communication between the fracture and pore pressure system. This study suggests that the effects of external temperature and dead volume on pore pressure response and injected volume should be evaluated for accurate laboratory characterization and inter-laboratory comparison.
基金Supported by the National Natural Science Foundation of China (50802069)
文摘Based on thinned fiber Bragg grating and polymer material, we propose a novel high-sensitivity pressure sensor and obtained a new contribution to the pressure sensitivity, which is dependent on the derivative of the effective refractive index （RI） of core mode with respect to the surrounding medium RI, as well as on the relationship between the polymer RI and the pressure; moreover, it is inversely proportional to Young＇s modulus of the polymer material. For the polymer with Young＇s modulus of 1.0 MPa, the total pressure sensitivity 1.54×10-2 MPa-1 can be obtained.
文摘A new type optical fiber sensor--Tip timing Sensor is introduced in this paper. It is mostly used in vibration measurement of turbine blade, which can realize real-time and non-contact measurement.
