A building information model for pipes already in place is essential in maintenance, for example, mending, reconstruction, and modernizing. However, current point cloud construction methods are not suited to complex piping systems, and many point cloud merging methods perform poorly in complex piping environments. To provide critical functions for constructing pipe point clouds from digital photogrammetry, a feature type selection network (FTSNet) is proposed. First, a digital photogrammetry method combining FTSNet with handcrafted features is proposed. Second, a piping data set of various piping scenes is constructed and evaluated using the developed data capturing device. A training data set and the corresponding network output categories are determined according to pose‐estimation performance using different image feature types. Finally, experiments conducted on the final test data set indicate that, together, digital photogrammetry and FTSNet can improve accuracy, flexibility, and processing speed.
A series of W-Al nanolayer coatings were deposited with varying content of aluminum from 0 at.% to 65 at.% by a unbalanced magnetron (UBM) sputtering system. The as-deposited coatings were investigated first. Then, the coatings were oxidized aiming to study their oxidation behavior. SEM, TEM, XRD, GDOS and nanohardness tester were used. The results showed that the Al content had a significant effect on the performance of W-Al coatings. The hardness of as-deposited and oxidized coatings decreased with increasing Al content. The pure W coating was heavily oxidized. As the Al content increased, the oxidation decreased fast and then remained stable as the Al content was higher than 45at.%. The effects of formed oxides on hardness were discussed.
W(100-x)%Cx% coatings with different tungsten and carbon contents were deposited by unbalanced magnetron sputtering. The microstructures and mechanical properties of the W(100-x)%C x% coatings was characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), nanoindentation and adhesion testing techniques. The tribological performance of the coatings was investigated using a pin-on-disc trobometer under dry conditions. Experimental results indicated that coating microstructure, mechanical properties and wear resistance varied according to the tungsten and carbon contents of the coatings. The W72%C28% coating had the highest hardness/elastic modulus (H/E) ratio. In the ball-on-disc wear tests, it was found that the W72%C28% coating exhibited the best wear resistance.
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