Herein, a precise positioning system for mine personnel based on the ultra wide band (UWB) technology is proposed, and the basic principle of typical SDS-TWR algorithm is analyzed. Using mine CAD drawings and two-dimensional (2D) coordinate positioning algorithm, this is the first study to realize a comprehensive management system of real-time, dynamic, synchronous tracking and monitoring, high-precision positioning, and trajectory playback in a 2D-CAD plane. The system has been tested at the Mazhuang Iron Mine of Laiwu Mining. Experimental results show that within 200 m of the UWB signal coverage, the positioning error of the system with respect to a static target is less than 30 cm, and the positioning error of a dynamic target is less than 1.65 m with a moving speed of 25 km/h. The system meets the requirements of personnel positioning in coal mines and has a broad market potential and application values.

There is a great demand for online monitoring of various characteristic gases in the precision fermentation process. In this paper, based on the tunable diode laser absorption spectroscopy (TDLAS) technology, the carbon dioxide monitoring and analysis system was developed for the detection of gases in the precision fermentation process. The measurement range of 0~2% and the response time of 5.46 s were realized. In addition, the measurement error can be lower than 0.08% within the full measurement range. The results of field test demonstrated the advantages of high sensitivity, excellent stability, and reliability of the developed CO₂ monitoring system. The CO2 monitoring system based on the TDLAS technology is extremely suitable for insitu characteristic gas monitoring and has great application potential in the precision fermentation process. 

Aiming at the demand of high-precision water pressure measurement in wells, this paper designed a high-sensitivity fiber Bragg grating pressure sensor based on the pressure sensing characteristics of bellows and a cantilever beam-based lever amplification structure. The axial structure of the bellows under pressure is amplified by the lever structure connected by the hinge to the axial strain of the FBG to achieve high-precision measurement of pressure. The mechanical model of the mechanical structure of the sensor is established. The mathematical expression of the wavelength change and pressure of the FBG in the sensor is derived. The pressure sensitivity of the sensor is simulated by the finite element method. The simulated and experimental pressure sensitivities of the sensor are 14.8 pm/kPa and 14.1 pm/kPa, respectively, which are in good agreement. The pressure sensor can accurately measure a certain range of pressure, and by changing the lever arm length parameter, the sensitivity can be changed and the measuring range can be adjusted.

Optical fiber sensors based on fiber Bragg grating(FBG), Fabry-Perot cavity (FP cavity) and distributed system were discussed here, their application status in nuclear environment was introduced in detail and the influence of nuclear radiation on the sensors were summarized. Among sensors based on FBG written on naked and doped optical fibers, gratings written on pure silicon fibers and fibers doped with some fluorine (F) show the best properties. When it comes to distributed optical fiber sensors, compared with sensors based on Rayleigh scattering, the ones based on Brillouin and Raman scattering can be more radiation resistive to some extent. For FP cavity based optical fiber sensors, they cannot work normally in nuclear radiation environment for their unique structures. At present, the application of optical fiber sensors in nuclear radiation environment is still strictly limited because of the sensitivity of optical fiber to nuclear radiation,for the shift of peak wavelengths and signal attenuation always occur on the radiated fibers, which affect the long-term stability of the fibers.In order to realize the large-scale application of optical fiber sensors in nuclear radiation environment, the future development direction is to develop optical fibers with stronger radiation resistance and find novel calibration and signal processing methods to improve the response accuracy of sensors.

Aiming at the high precision and rapid measurement of the downhole temperature profile, a new kind of walking highprecision fiber grating temperature sensor was designed in this paper. The ultrafine stainless steel tube was used for pressure encapsulation. The theoretical simulation of the temperature response speed was carried out, and the impact of the downhole high pressure on the measurement accuracy was analyzed. The sensor with a diameter of 1.2 mm was demodulated by commercial highprecision demodulator. The results show that the resolution of the FBG temperature sensor is better than 0.01 ^oC, the linear range of the temperature reaches 175 ^oC, the response time is less than 108 ms, and the resistance to pressure is up to 100 MPa. This sensor can meet the needs of rapid measurement of the oil well temperature profile.

For the problem that the phasesensitive distributed vibration detection system is susceptible to environmental noise in practical engineering applications, theoretical simulation and field test verification of the filtering algorithm were performed on the system signal. The results show that the highpass filtered differential and average processing of the original signal can effectively remove largescale, lowfrequency and periodic noise signals in the environment. The system signalnoise ratio is improved by 50% and the detection effect is enhanced.

To solve the problem of pipe thickness online nondestructive testing in the explosive surroundings of oil refinery area, a novel EMAT system with maximum lift-off value of 6 mm has been developed in the way of focusing magnetic field and optimizing the testing coil. Experiment results show that the testing accuracy was less than 0.05 mm for standard test block with thickness of 22 mm and the serviced pipeline with thickness of 12.16 mm when the condition of liftoff value was less than 6 mm. The developed EMAT system in this work can satisfy the requirement of pipeline thickness detection in the refining factory, which provides the ability of explosionproof design and certification for EMAT technology.

Laser-induced breakdown spectroscopy (LIBS) technique is widely used to analyze the composition and the concentration of elements in materials，which is based on the atomic excitation and emission spectrum. It has many advantages, such as rapid, multielement simultaneous detection and without sample pretreatment. In this paper, research progress on the application of metal element detection in such fields as alloy, soil, water, and food is reviewed. It is considered that there are some problems in this technology at present, such as low detection accuracy, poor repeatability, unstable detection signal. It is also found that the research and development of LIBS based metal element detection instrument should be developed towards the direction of conventional, portable and high precision.

Based on the Raman scattering temperature effect and the optical time domain reflection technology, a 100 MHz highspeed data acquisition system SDLaser_DAQ600 was developed to measure the temperature field of space environment. In the data acquisition system, using real time averaging algorithm in the FPGA, DAQ600 has realized 65 536 times cumulative averaging for original fiber sensor signals, which supported realtime sampling of 10 km length fiber with 1 m spatial resolution.The experimental results show that, signaltonoise ratio for optical fiber sensing can be increased to more than 90 dB through the 65 536 times cumulative averaging. Finally, smooth curves of Stokes and antiStokes have been obtained, which could provide proper data support for distributed temperature system measurement.

The actual laser Doppler velocimetry signal mixed up much noise, so it was difficult to find the required Doppler frequency shift. In this paper, a wavelet packet global threshold denoising method was proposed to solve this problem, which was also used to process Doppler velocimetry signal in MATLAB. According to the characteristics of the Doppler signal, through the selection of wavelet packet decomposition scale, the comparison of threshold estimation methods and the adjustment of threshold thr, the developed method could quickly and effectively eliminate the noise signal, improve the SNR and obtain useful signals.

For the differential structure based optical fiber strain sensor, temperature and stress affect two gratings, and there is temperature and strain cross interference. The traditional temperature compensation algorithm does not consider the influence of the thermal expansion of the package structure on the center wavelength of the grating. There are some shortcomings in the theory of the algorithm, which are likely to cause measurement errors in the practical application of the project. In this paper, the sensitivity of the whole structure after encapsulation was analyzed, and the temperature sensitivity coefficient of the gratings was obtained by the experiment. The theoretical deduction was simplified and the strain measurement was carried out. The results show that after temperature compensation, the center wavelength difference between the two gratings is linearly related to the pressure. The linear correlation coefficient is 0.7 pm/Pa with a fit of 0.999 5, which can effectively suppress the effect of temperature on the wavelength.

In this paper, a new type of distributed fiber seismic wave detection system for oil and gas exploration was designed. And based on buried layout mode, the advanced practical layout optimization scheme of adding caudal vertebrae to optical cable was put forward. Field test results showed that the system could completely detect the distribution of seismic waves along the cable and the waveform characteristics were similar to those of traditional electronic dynamic sensors. The buried layout mode has the maximum detection distance of up to 20 m and the maximum distance of the caudal vertebral layout mode can reach 10 m. The research provides necessary theoretical and technical support for the extensive application and transformation of the new system.

Based on the principle of fiber Bragg grating (FBG), an optical fiber sensor was designed to directly measure the internal temperature of transformer winding, and the packaging technology and material of the sensor were optimized, which could solve the problems caused by thermal field and stress. After the temperature calibration experiment, the temperature calibration was carried on to the optical fiber temperature sensors. The field experiment showed that good consistency and repetition of temperature measurement were kept between the optical fiber temperature sensor and the electronic sensor, and the system’s measurement sensitivity is less than 0.1 ℃, and the measurement accuracy is up to ±0.5 ℃, which meets the requirements of the realtime online detection of the internal temperature of the transformer winding.

The outofplane displacement can be measured by using a vortex beam, Laguerre Gaussian (LG) beam, produced by computergenerated hologram (CGH) grating. Based on the principle of using the computergenerated hologram (CGH) grating to produce LG beam, the experimental scheme of the outofplane deformation measurement was designed, using the LG beam as reference light and a plane beam as object light. The object deformation was measured by the interference of object light and reference light, and the interference beam intensity formula before and after the tested object deformed was derived. Adopting the method of numerical calculation, the principle of using LG beam for the measurement of object deformation was analyzed. The numerical simulation results were in agreement with the theoretical results, which showed that by the high purity LG beam produced by CGH grating can be used for outofplane displacement measurement.

Based on fiber Bragg grating (FBG), a rapid response temperature sensor suitable for marine disposable measurement was designed in this paper. The temperature sensitivity of the sensor was calculated by theory, and the response time of the sensor with different structural parameters was simulated and analyzed using the finite element method. A sensor with response time 17 ms was designed, and its theoretical sensitivity was calculated to be 30.7 pm/℃. This sensor is suitable for rapid measurement of ocean temperature.

In order to realizing the realtime monitoring of the seepage pressure of the tailing pond, a kind of corrugated diaphragm based optical FBG seepage pressure sensor was designed. The influence of the ambient temperature was eliminated by the double temperature compensation of the material and temperature grating. The experimental results show that the pressure measuring range is 0~20 kPa, the pressure sensitivity is 27.8 nm/MPa, the linearityfitted is up to 0. 999 99, which is suitable to high accurate measurement of the liquid level changes within narrow range. The application of the sensor in the detection of saturation line of tailing pond shows that the sensor possesses the advantages of high precision and good repeatability.

Based on fiber Bragg grating sensing technology, we designed an online monitoring system for the pantograph of an electric locomotive. It could monitor realtime dynamic pressure, vibration state, slide stress and temperature of the pantograph. Through simulation, calibration and
testing, we acquired monitoring range of dynamic pressure of 0 ~500 N, and monitoring scope of microstrain of -0.2% ~0.2%.

Wedesign and implement a cRIO based remote distributed data acquisition system. It applies cRIO specific 1588 plug-in to the design of time synchronization program, data acquisition, trigger preservation, local preservation and data TCP/IP upload. Data acquisition and test results show that its short-term synchronization precision can reach sub-millisecond level, and millisecond level for long-erm test. It can be applied to optical fiber micro-seismic monitoring system in coal mines.

Laser radar has been broadly applied in atmospheric detection and weather monitoring due to such characteristics as good direction, coherence, monochromaticity and small volume. We survey its latest research advances and application status quo in atmospheric detection. We think its main issue is easily susceptible to environmental change. It will develop towards highaccuracy, highperformance and intelligence.

We develop strain, tilt and acceleration sensors with strain accuracy of 5 με, tilt angle precision of 0.02°, and acceleration sensitivity of 800 pm/g below 40 Hz, based on the principle of fiber Bragg grating (FBG).We further employed them to establish a safety monitoring system for the jacket structure of offshore platform. We implement online monitoring for pileleg supporting force, platform tilt and swing amplitude. We also calculate its strain situation by constructing a mechanical model for jacket structure, analyze the security of the jacket structure and conduct alert.The system has been successfully applied in an oil platform at South China Sea, and provide security guarantee for the jacket structure.

We devise an optical fiber grating based temperature sensor for such issues as traditional electronic sensor failing to work in microwave field in bone tumor microwave hyperthermia, a probe apt to fracture when stuck into periosteum and to short life time. It includes a temperature sensing probe and a fiber grating multipoint temperature detector. Its special integration structure design and packaging technology and 0.5 mm wall thick probe improve its mechanical strength, especially for its probe. This guarantees its whole sealing performance.Stainless steel material extends its life time.Experimental results show that it has detection accuracy of±0.3 ℃ and temperature response time of 5 s.Clinical application demonstrates that it has high resolution of 0.01 ℃,high accuracy and reliability and strong electromagnetic interference suppression capability.

We design an online monitoring system for mechanical and electrical equipment based on fiber Bragg grating sensing technology. Test results show that it has better frequency response and repeatability. We apply the system to the vibration monitoring for a turbine and implement realtime and online status monitoring for an electrical and mechanical equipment. Its detection result is basically identical to those of a standard acceleration sensor and a handset speedometer. Longterm application shows that it has higher accuracy and stability.

Linear least squares fitting is only applicable to gas detection whose spectral absorption rate is less than 0.1 in coal mine optical fiber gas detection. We present the calculation for gas concentration with damped least squares fitting for the nonlinear issue between the varieties of gas absorption spectrum and concentration if spectral absorption rate increases. Experimental results show that the detection limitation of the method based gas detector is improved from 100 ppm to 30 ppm.Data calibration procedure is also simplified, so the method can better satisfy the requirements of coal mines for secure production.

We design a new high sensitive fiber grating gas pressure sensor with temperature compensation based on a thinwalled cylinder structure to improve the precision and accuracy of gas pressure sensing. We determine its structure and size through theory analysis. It has a thinwalled cylinder structure with inner diameter of 15 mm, wall thickness of 0.13 mm and 30CrMnSiA as material. Its sensitivity is 220 pm/MPa.The drift amount of its fiber grating central wavelength is 2.93 nm when gas pressure is 10 MPa.It has error of less than 0.05 MPa and better reproducibility.Practical application shows that it has higher accuracy and can overcome the impact of temperature on measurement results.