U_i range

Class name and temperature range

(0.0 ≤ U_i < 0.2)

Class 1: very law temperature

(0.2 ≤ U_i < 0.4)

Class 2: law temperature

(0.4 ≤ U_i < 0.6)

Class 3: moderate temperature

(0.6 ≤ U_i < 0.8)

Class 4: high temperature

(0.8 ≤ U_i ≤ 1.0)

Class 5: very high temperature