“…According to Equations ( 21) and ( 22), among the seven orders, orders 1 and 2 are high-level orders, orders 3 and 4 are intermediate-level orders, and orders 5, 6 and 7 are basic-level orders. Among the 36 machines, machines 1, 2, 3,4,10,11,12,13,19,20,21,22,28,29,30 and 31 belong to the high-health group machine set, machines 5,6,7,14,15,16,23,24,25,32,33 and 34 belong to the medium-health group machine set, and machines 8, 9, 17, 18, 26, 27, 35 and 36 belong to the sub-health group machine set.…”