@article{ref1,
title="Approximate the scheduling of quay cranes with non-crossing constraints",
journal="European journal of operational research",
year="2017",
author="Zhang, An and Zhang, Wenshuai and Chen, Yong and Chen, Guangting and Chen, Xufeng",
volume="258",
number="3",
pages="820-828",
abstract="In port container terminals, the scheduling of quay cranes (QCs) for a container vessel is one of the most critical operations. This paper investigates the problem of scheduling quay cranes with non-crossing constraints, wherein QCs cannot cross over each other because they are on the same track. The objective is to minimise the makespan of a container vessel, which is the latest completion time among all handling tasks of the vessel. Compared with several 2-approximation algorithms in the literature, this paper presents an approximation algorithm with a worst case ratio 2−2m+1<2 for any m QCs. This ratio is demonstrated to be the best possible among all partition-based algorithms in the literature. Besides, we study the scheduling of two quay cranes with different processing speeds. For an arbitrary speed ratio s ≥ 1, an approximation algorithm with worst case ratio (1+s)21+s+s2 is provided.<p /> <p>Language: en</p>",
language="en",
issn="0377-2217",
doi="10.1016/j.ejor.2016.10.021",
url="http://dx.doi.org/10.1016/j.ejor.2016.10.021"
}