To address the problem of early warning of pipeline leakage, this letter proposes a pipeline leakage early warning method based on DAS. Through DAS monitoring the vibration signals induced by different degree of pipeline corrosion and blockage, using pattern recognition techniques, distributed early warning and location of pipeline leakage are realized. By conducting simulations and experimental analyses, the differences in vibration characteristics caused by four types of pipeline anomalies were validated. Combining wavelet packet energy ratios and the BP neural network, the average recognition rate for the five event classes (normal pipeline, 40% corrosion, 80% corrosion, 40% blockage, 70% blockage) was 95.39% based on 3910 samples. The results demonstrate that the proposed method can effectively achieve the early warning of pipeline leakage.

The Chinese space station is designed to carry out manned spaceflight, space science research, and so on. In serious applications, it is a common operation to inject gas into the hull, which can produce strain of the bulkhead. Accurate measurement of strain for the bulkhead is one of the key tasks in evaluating the health condition of the space station. This is the first work to perform strain detection for the Chinese space station bulkhead by using optical fiber Bragg grating. In the period of measurements, the resistance strain gauge is used as the strain standard. The measurement error of the fiber optical sensor in the circumferential direction is very small, being less than 4.52 με. However, the error in the axial direction is very large with the highest value of 28.93 με. Because the measurement error of bare fiber in the axial direction is very small, the transverse effect of the substrate of the fiber optical sensor likely plays a role. The comparison of the theoretical and experimental results of the transverse effect coefficients shows that they are fairly consistent, with values of 0.0271 and 0.0287, respectively. After the transverse effect is compensated, the strain deviation in the axial detection is smaller than 2.04 με. It is of great significance to carry out real-time health assessment for the bulkhead of the space station.

The genetic algorithm (GA) method is used to demodulate the strain distribution of fiber Bragg grating (FBG), which improves the residual stress measurement accuracy of tube in the hole-drilling method. The accuracy of the method is verified by simulation and experiment. Compared with the traditional peak demodulation, the residual stresses error is reduced from 10% ~ 20% to 0~5% by GA. The results show that the utilizing of the GA method can effectively improve the accuracy of residual stress measurement of tube based on FBG, which promotes the application of FBG in the measurement of residual stress in special-shaped components, and expands the range of FBG residual stress measurement.

In the process of flight for in-orbit spacecraft, debris and particles in space will collide with the spacecraft at a high speed. These collision will produce strain, pit or perforation on the surface of the spacecraft cabin, forming damage accumulation. Therefore, it is necessary to monitor the strain and impact position of the spacecraft cabin in real time, which will provide a basis for ensuring the reliability and safety of the spacecraft. In this paper, the achievement of strain and vibration information during the process of impact is designed in two ways: touched style and untouched style. The design of touched style needs to meet the requirements of large capacity/ultra-high speed monitoring. The design of untouched style needs to meet the acquisition of high frequency vibration signal in the impact process.

A surface reconstruction method based on Tafel curves corrected is proposed, which corrects of interpolation curvature by determining the position of loading points and reduces the error of surface reconstruction. Fixed boundary conditions around the surface are used to correct the surface reconstruction results, the error of the reconstructed surface is reduced. Through finite element simulation and experimental verification by carbon fiber board with size of 600×600×0.5mm and 50 FBGs sensors network. Compared with traditional surface reconstruction methods, Tafel curves corrected method can double the curvature accuracy, and surface reconstruction RMS reduced to 0.0247cm. It`s shows the significant advantage of the method in improving the accuracy of surface reconstruction of the surrounding fixed plate, can promote health monitoring of flexible panels in fields such as aviation construction.