Aiming at the application of the overhead transmission line insulator patrol inspection requirements based on the unmanned aerial vehicle (UAV), a lightweight ECA-YOLOX-Tiny model is proposed by embedding the efficient channel attention (ECA) module into the lightweight YOLOX-Tiny model. Some measures of data augmentation, input image resolution improvement and adaptive cosine annealing learning rate are used to improve the target detection accuracy. The data of the standard China power line insulator dataset (CPLID) are used to train and verify the model. Through a longitudinal comparison before and after the model improved, and a cross-sectional comparison with other similar models, the advantages of the proposed model are verified in terms of multi-target identification for normal insulators, localization for small target defect areas, and the parameters required for calculation. Finally, the comparative analysis between the proposed ECA-YOLOX-Tiny model and YOLOV4-Tiny model is given by introducing the visualization method of class activation mapping (CAM). The comparative results show that the ECA-YOLOX-Tiny model is more accurate in locating the self-explosion areas of defective insulators, and has a higher response rate for decision areas and some special backgrounds, such as the overlapping small target insulators, the insulators obscured by tower poles, or the insulators with high-similarity backgrounds.

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The joint interface plays a significant role in machine tools and other machineries. A novel type of joint which consists of oily porous material was proposed. The equivalent stiffness and damping of oily porous joint could be divided into solid and liquid parts, and the two parts are shunt connection. Theoretically, the stiffness and damping of solid part were established using Hertz contact and fractal theory, and the liquid counterpart was also deduced from the average flow of generalized Reynolds equation through a correlation parameter A r . It was concluded from simulation and calculation that the total equivalent stiffness of oily joint is increased with D and decreased with increased G. The experiment was carried out to compare the normal characteristics of porous material-steel oily joint with non-media steel-steel joint, and the result was that the joint which contains an oil film interlayer formed by porous and steel is superior to the joint with non-media formed by steel in stiffness and damping characteristics. In the case of the same preload, the former's stiffness is increased by about 30 %, and the damping is increased about five to six times meanwhile.

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