Please polish the following paragraph according to the style of SCI journalsThermocouples can only measure the temperature of discrete points of the tunnel but cannot measure the continuous temperatur

Thermocouples are limited in their ability to measure the temperature of discrete points within a tunnel, as they are unable to capture the continuous temperature field of the tunnel. In contrast, infrared thermography is capable of measuring the continuous temperature field of the tunnel surface. During a fire test, the outer surface temperature of the tunnel was monitored using infrared thermography, as depicted in Fig. 12. It is important to note that the lens angle of the infrared thermography was narrow, and therefore not all areas of the ceiling could be monitored. Analysis of Fig. 12 reveals that at the 100-minute mark, the temperature in the cracked area of the ceiling (approximately one-third of the tunnel's cross section) increased significantly, while the temperature in the uncracked area of the ceiling remained notably lower. At this time, the macroscopic test phenomenon of the outer surface of the tunnel is shown in Fig. 5, where cracks were observed to be distributed irregularly, and boiling water vapor overflowed from the concrete cracks. This observation suggests that the high temperature at the concrete cracks resulted from water and vapor in the high-temperature areas of the concrete migrating to the surface through the cracks, and subsequently heating the concrete at the cracks. A frame-by-frame analysis of the infrared image, combined with macroscopic observations of concrete cracking during the fire test, allowed for the identification of the distribution of the main cracks on the outer surface of the immersed tunnel, as presented in Fig. 13