This paper presents a new image enhancement method based on self-adaptive piecewise linear transformation. It is most important to select division points during the processing course of piecewise linear transformation because these division points can decide the quality and efficiency of image enhancement. In this paper, division points are automatically and self-adaptive selected based on the gray grade and histogram feature of images. In order to increase the contrast of the image, it is necessary to extend the object section, maintain the transition section and compress the background section. Our method is easy to use, and the experiment results show that the technique can produce good results on a variety of images.
Since the magnetic flux leakage (MFL) for cracks inspection in pipelines can be influenced by stress concentration, it is
very difficult to characterize and size the crack or crack-like defects. Thus, the theory model of magnetization and
permeability under mechanics-magnetic coupling was derived by thermodynamic equation firstly, and the effects of the
applied stress on magnetization and permeability were analyzed theoretically. The finite element method (FEM) under
mechanics-magnetic coupling was studied, and the relationship of the crack’s MFL and loaded stresses were simulated
and studied using the 3D FEM. And the simulation results were verified by experiments with the help of material testing
system (MTS). The simulation and experimental results demonstrate that the experimental results are basically consistent
with simulation results, and the MFL density caused by cracks decreases with the applied stress increasing gradually.
Therefore, the higher sensitivity sensors should be employed in the MFL measurement for pipeline cracks and the testing
data should be compensated while quantitative interpretation.
This paper briefly introduces the design of control network based on OMRON PLC; and describes in detail step and setting of design based on three kinds of network: Ethernet, controller link and CompoBus/D. The design has been applied to lab construction. The practice shows that it is valuable for teaching and scientific research.