An improved Faster-RCNN defect recognition model is proposed for the recognition of hydraulic cylinder internal surface damage defects of hydraulic supports. ResNet-50 is used instead of the original feature extraction network VGG16. Meanwhile, the anchor window generated by the region suggestion network is improved using the K-means clustering algorithm, the original ROI pooling operation is replaced by RoI Align to solve the region mismatch problem caused by the quantization operation, the soft non-maximal value suppression algorithm is used for screening, and the difficult negative sample mining method to optimize the model training process to improve the generalization ability of the model. The experimental results demonstrate that the mAP of the model on the dataset is improved by 5.87% compared with the original model, reaching 81.26%.
Aiming at the problems of large internal heat generation and uneven heat dissipation of cylindrical power battery module of electric vehicle, a new divergent heat dissipation model of cylindrical battery is proposed. A certain type of 18650 batteries is taken as an example to simulate and analyze its temperature field. The results show that the temperature distribution law of batteries located on the same concentric circle is almost the same. For the single cell, the overall temperature distribution shows the following law: the temperature gradually decreases from inside to outside of the battery. The temperature gradually decreases from top to bottom of the battery . The temperature near the center of the flow field is low. The temperature away from the center of the flow field is high. The change rate of the maximum temperature and the maximum temperature difference of the battery pack gradually decreases with the increase of mass flow rate. The change rate of the maximum temperature and the maximum temperature difference of the battery pack gradually decreases with the increase of the center distance. And the lowest is -1.59% and -14.95%. It provides a reference for the future research on heat dissipation of cylindrical battery
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