An Improved Discrete PSO for Tugboat Assignment Problem under a Hybrid Scheduling Rule in Container Terminal

Table 1

Assignment rules between ships and tugboats.

Length of ship (m)	Required horsepower (ps) of tugboats	Required number of tugboats	Docking operation time (min)
0–100	2600	1	40
100–200	5200	2	48
200–250	6400	2	60
250–300	6800	2	75
300	8000	2	85