A real-time detection model for smoke in grain bins with edge devices.

The global food crisis is becoming increasingly severe, and frequent grain bins fires can also lead to significant food losses at the same time. Accordingly, this paper proposes a model-compressed technique for promptly detecting small and thin smoke at the early stages of fire in grain bins. The proposed technique involves three key stages: (1) conducting smoke experiments in a back-up bin to acquire a dataset; (2) proposing a real-time detection model based on YOLO v5s with sparse training, channel pruning and model fine-tuning, and (3) the proposed model is subsequently deployed on different current edge devices. The experimental results indicate the proposed model can detect the smoke in grain bins effectively, with mAP and detection speed are 94.90% and 109.89 FPS respectively, and model size reduced by 5.11 MB. Furthermore, the proposed model is deployed on the edge device and achieved the detection speed of 49.26 FPS, thus allowing for real-time detection.

Investigation on the Microstructure and Mechanical Properties of CNTs-AlSi10Mg Composites Fabricated by Selective Laser Melting.

CNT-AlSi10Mg composites fabricated by SLM have drawn a lot attention in structural application due to its excellent strength, elasticity and thermal conductivities. A planetary ball milling method was used to prepare the carbon nanotube (CNT)-AlSi10Mg powders, and the CNT-AlSi10Mg composites were fabricated by selective laser melting (SLM). The density, microstructure and mechanical properties of CNT-AlSi10Mg composites were studied. The density of the test samples increased at first and then decreased with increasing scan speed. When the laser scan speed was 800 mm/s, the test sample exhibited the highest density. The hardness increased by approximately 26%, and the tensile strength increased by approximately 13% compared to those values exhibited by the unreinforced AlSi10Mg. The grains of CNT-AlSi10Mg composite are finer than that in the AlSi10Mg. The CNTs were distributed along the grain boundaries of AlSi10Mg. Some of the CNTs reacted with Al element and transformed into Al4C3 during SLM, while some of the CNTs still maintained their tubular structure. The combination of CNTs and Al4C3 has a significant improvement in mechanical properties of the composites through fine grain strengthening, second phase strengthening, and load transfer strengthening.