基于红外热成像的林地余火死灰复燃点诊断方法研究

林地余火阴燃特性具有隐蔽性强、持续时间长、目测难度大、且具有死灰复燃等特点，从而一直困扰森林火灾的彻底扑灭。为了及时、高效地发现林地余火阴燃点，探索林地余火死灰复燃的特征及规律，在南京森林警察学院点烧基地里进行测试实验，以无人机搭载热红外成像系统、气象采集系统等为工具，把火源点设置在杨树林内，人为干预进行点烧、熄灭、复燃等重复实验，实验包括白天和夜晚两个时间段，用安装于无人机上的红外热成像仪对火源进行观测。实验表明：林地余火死灰复燃的温度在500～600℃，离散程度较大；林地余火死灰复燃在白天的时间普遍短于夜晚时间，表明外界温度越高，越会促进林地余火死灰复燃的速率；在森林中，不同地点、不同时间段的森林背景温度标准差比较稳定，主要处于1～9 之间；林地余火红外图像的温度数据的标准差值分布在30～85之间；红外图像的温度数据的标准差值分布在55～85 之间，则可定为死灰复燃可疑阶段。该方法量化了死灰复燃的火环境及温度参数阈值，明确林地余火阴燃点引燃特征值。该研究成果将推动森林防火技术的发展，为安全扑火提供重要的方法和资料。

The Diagnostic Methods for Resurgences of Smoldering Fire in the Forests by Infrared Thermal Imaging

The embers in the forests are hard to be extinguished because of their smoldering combustion, such as concealing, long burning, invisible inspection and easy resurgence. To find the smoldering combustions timely and efficiently and to explore the characteristics and rules for the resurgences, a series of experiments have been presented in this study. With the help of a drone equipped with thermal infrared imaging system and meteorological data collection system, some experiments were conducted in the poplars in Nanjing Forest Police College, where ignitions were set, lighted, put out and resurged by human intervention. The embers were observed by the Infrared Radiometer on the drone in the daytime and at night. The results showed that the dispersion was bigger when the temperature of smoldering combustion was between 500～600 ℃, and the easier resurgence in the daytime than at night suggested that the higher external temperature the ember was, the easier resurgent it was. It was pointed that the temperature in forests was relatively stable in different plots and in different time, with a standard deviation of 1 and 9. The standard deviation of temperature data on the infrared images of embers varied from 30 to 85 and it revealed that the values between 80 and 85 would be suspected. In this method, the surroundings and parameter threshold of temperature in the smoldering combustions could be quantified to determine their eigen values of embers in the forests. It is reasonable for the researchers at this point to promote the development of the technology in the forest-fire prevention and the decision-makers to ask which results could provide some important methods and data for safe fire-fighting.