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Introduction: As a new and efficient method for obstacle removal, laser clearance has promising applications in eliminating tree obstacles in transmission lines. This paper aims to explore various aspects related to the laser ablation of tree obstacles in transmission lines through simulation and experimentation. Methods: This paper employs simulation and experimentation to test the ignition time, burn-through time, peak temperature, and basic carbonization rate of various types of tree obstacles in transmission lines. Additionally, it analyzes the effects of tree density, laser power, clearance distance, and tree moisture content on laser ablation characteristics. Results: The results reveal that different types of tree obstacles exhibit distinct ablation characteristics. With increasing tree density, both the ignition and burn-through times increase, while the peak temperature and basic carbonization rate decrease. Additionally, laser power and clearance distance significantly influence laser ablation behavior. Higher laser energy density results in greater heat flux density, leading to shorter ignition and burn-through times and higher peak temperatures and carbonization rates. Moreover, the tree obstacle with the highest moisture content (58.4%) had the shortest burn-through time of 46.56 s, whereas the one with the lowest moisture content (14.8%) took the longest at 58.41 s, which demonstrates that increased moisture content enhances the laser ablation rate. Discussion: These findings provide a basis for the application of laser-based tree obstacle removal in power transmission lines. The understanding of how different factors such as tree density, laser power, clearance distance, and moisture content affect the laser ablation process can help in optimizing the laser clearance operations for more efficient removal of tree obstacles in transmission lines. [ABSTRACT FROM AUTHOR]

IntroductionAs a new and efficient method for obstacle removal, laser clearance has promising applications in eliminating tree obstacles in transmission lines. This paper aims to explore various aspects related to the laser ablation of tree obstacles in transmission lines through simulation and experimentation.MethodsThis paper employs simulation and experimentation to test the ignition time, burn-through time, peak temperature, and basic carbonization rate of various types of tree obstacles in transmission lines. Additionally, it analyzes the effects of tree density, laser power, clearance distance, and tree moisture content on laser ablation characteristics.ResultsThe results reveal that different types of tree obstacles exhibit distinct ablation characteristics. With increasing tree density, both the ignition and burn-through times increase, while the peak temperature and basic carbonization rate decrease. Additionally, laser power and clearance distance significantly influence laser ablation behavior. Higher laser energy density results in greater heat flux density, leading to shorter ignition and burn-through times and higher peak temperatures and carbonization rates. Moreover, the tree obstacle with the highest moisture content (58.4%) had the shortest burn-through time of 46.56 s, whereas the one with the lowest moisture content (14.8%) took the longest at 58.41 s, which demonstrates that increased moisture content enhances the laser ablation rate.DiscussionThese findings provide a basis for the application of laser-based tree obstacle removal in power transmission lines. The understanding of how different factors such as tree density, laser power, clearance distance, and moisture content affect the laser ablation process can help in optimizing the laser clearance operations for more efficient removal of tree obstacles in transmission lines.

Under different heating conditions, the composite wood floor and pine carbonization samples were prepared, and the charring surface morphology, crack width, carbonization depth and average charring rate were compared and analyzed. The results show that under the thermal radiation condition, the carbonization of composite wood floor is the most serious, and cracks distributed radially; under the arc condition, the compound wood floor is difficult to ignite, and the carbonization layer is shallow; small amount spilled gasoline combustion has little effect on carbonization degree, but the char is obvious at the corner; at the same heating condition, the carbonization degree of pine was more serious than the composite wood floor, and the carbonized surface morphology had significant differences. [ABSTRACT FROM AUTHOR]

Abstract: This study uses fuel cell gas diffusion layers (GDLs) fabricated in the laboratory from carbon fiber cloth with different structure in proton exchange membrane fuel cells (PEMFCs), and investigates the relationship between the structure of the carbon fiber cloth and fuel cell performance.The paper discusses the relationship between fuel cell performance and structure of the carbon fiber cloth, and also examines the effect of the carbon fiber cloth’s thickness, air permeability, surface resistivity, XRD and elemental analysis. Carbon fiber cloth is carbonized at rates of 190, 220, 250, 280, and 310°Cmin−1 respectively, and the resulting carbon fiber cloth is tested in cells. When the test piece area is 25cm2, the test temperature 40°C, the gasket thickness 0.36mm, and the carbonization rate 280°Cmin−1, a fuel cell using the carbon fiber cloth achieves a current density of 1968mAcm−2 and a maximum power density of 633mWcm−2 at 0.3V. [Copyright &y& Elsevier]