Pipe cracks detection based on machine vision is a new and effective technology. However, it requires high quality of the image. Moreover, images with adequate lighting, evident cracks, clean backgrounds are difficult to obtain in practice. This paper proposes an algorithm for pipe cracks detection in natural background. The algorithm performs filtering, background segmentation, edge detection, threshold segmentation, morphological contour extraction and annotation on the image. This paper also proposes an adaptive threshold segmentation method to obtain the clear crack. By comparing the proposed algorithm with the DEE algorithm, the result shows that the proposed algorithm has certain advantages in experiments. The experiment results show that the algorithm proposed can be used in significant pipe cracks detection.

Abstract In order to have good accuracy, robustness and stability, it is necessary to control the manipulator accurately. But at present, for the precise control of manipulator, for the control mode and control system of manipulator, the research is not in-depth and perfect. This paper mainly summarizes the manipulator control system and control mode, and analyzes and summarizes the dynamics modeling, control accuracy, PLC control of the manipulator. At the same time, the control direction of the manipulator is prospected, such as cluster control, planning coordination control, autonomous motion control, etc.

A non-destructive testing method for three-dimensional stress of a glass cylinder based on photoelasticity is presented. Based on simulated stresses in the glass cylinder, intensity images output from a circular polariscope are calculated by Jones calculus. Therefore, the isoclinic angle and optical retardation can be simulated. Then the residual stresses in the glass cylinder can be reconstructed in cylindrical coordinates. By comparing the reconstructed stresses with numerical simulated stresses, there is good agreement but with some mismatches.

Residual stresses are important index to evaluate the precision molded glass plane. Residual stresses inside a glass cylinder was simulated by Finite Element Method. The circular polariscope was used to compare retardation and isoclinic angle between the simulated residual stresses and the thermal treated glass cylinder. The retardation and isoclinic angle of simulated residual stresses were calculated by Jones calculus. The comparison results show a good agreement.

Detection and localisation of pipeline leakage is an effective measure to save water resources. Generalised cross-correlation algorithm is widely used in leak detection. In this paper, by comparing the weighted algorithms of generalised cross-correlation functions, the GCC-PHAT algorithm is used to design a leak detection and positioning system, and relevant experiments are carried out. Multiple sensors are used (including flowmeters, pressure gauges and vibration sensors) to detect leaks and obtain relevant data in the experiment and locate the leak point through the GCC-PHAT algorithm. It is found that the method has better positioning performance through experiments.

In this paper, the fluid flow around a cylinder is taken as an example to study the different characteristics of fluid flow. Gambit is used to build a 2D model of the watershed and its cylinders, and divide the mesh and define the boundaries. The flow model was constructed with Fluent, the steady-state flow in this flow state is simulated and calculated. And draw the velocity vector of the steady flow of the fluid, use the velocity vector to clearly show the double vortex behind the cylinder. Finally, through Carmen vortex street flow simulation and other parameters, the single vortex frequency is calculated and compared with the single vortex frequency calculated by Fluent to verify the correctness of Fluent’s calculation.