Object Detection Based on an Improved YOLOv7 Model for Unmanned Aerial-Vehicle Patrol Tasks in Controlled Areas

When working with objects on a smaller scale, higher detection accuracy and faster detection speed are desirable features. Researchers aim to endow drones with these attributes in order to improve performance when patrolling in controlled areas for object detection. In this paper, we propose an improved YOLOv7 model. By incorporating the variability attention module into the backbone network of the original model, the association between distant pixels is increased, resulting in more effective feature extraction and, thus, improved model detection accuracy. By improving the original network model with deformable convolution modules and depthwise separable convolution modules, the model enhances the semantic information extraction of small objects and reduces the number of model parameters to a certain extent. Pretraining and fine-tuning techniques are used for training, and the model is retrained on the VisDrone2019 dataset. Using the VisDrone2019 dataset, the improved model achieves an mAP50 of 52.3% on the validation set. Through the visual comparative analysis of the detection results in our validation set, we find that the model shows a significant improvement in detecting small objects compared with previous iterations

An optimized synthesis route for high performance composite cathode based on a layered perovskite oxide of PrBa0.92CO2O6-delta with cationic deficiency

For Solid Oxide Fuel Cells (SOFCs) to become an economically attractive energy conversion technology, cathode materials with high catalytic activity over oxygen reduction reaction (ORR) and low cost are desired. In this work, a composite cathode material of PrBa0.92Co2O6-delta-40 wt%Ce0.8Sm0.2O1.9(OPCC) based on a layered perovskite oxide of PrBa0.92Co2O6-delta with Ba2+-deficiency at A-sites has been successfully synthesized with a facile and effective one-pot sol-gel method, which was comparatively studied with the counterpart BMCC synthesized with the traditional ball-milling method and the single phase cathode of PrBa0.92Co2O6-delta. Among the three cathodes, OPCC showed the lowest area specific resistances (ASRs) in both air and oxygen atmospheres, indicating the highest ORR catalytic activity. Such performance improvement for OPCC was closely related to its optimized microstructures obtained with the liquid-mixing one-pot synthesis method and existence of Ce0.8Sm0.2O1.9 that has a high ionic conductivity. I-V and I-P curves were measured for the anode-supported single cells with the three cathodes, and the OPCC-based cell showed the highest peak power densities with typical value of 1011 mW cm(-2) at 750 degrees C in contrast to 783 mW cm(-2) for the BMCC-based cell and 574 mW cm(-2) for the PrBa0.92Co2O6-delta-based cell respectively. The OPCC-based cell also showed a stable performance with no obvious degradation over 100 h at 700 degrees C. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved