Particle Swarm Optimization Algorithm for Unrelated Parallel Machine Scheduling with Release Dates

Table 10

The path of steepest descent for PSO.

Run		Coded units			Natural units			𝐶max	Improv.	Time
		𝐴	𝐷	𝐸	𝑅1	Pop. size	Iteration
0	Base	0	0	0	0.5	55	3000	117.30	—	50.68
	Increment = ▵	1	0.40	0.52	0.4	18	1044.4	—	—	—
1	Base + ∆	1	0.40	0.52	0.90	73	4044	114.80	0.021	82.61
2	Base + 2▵	2	0.80	1.04	0.90	91	5089	114.40	0.024	129.06
3	Base + 3▵	3	1.20	1.57	0.90	109	6133	114.95	0.002	193.28