关键词: 集装箱堆场, 外集卡提箱, 提箱策略, 到达时间随机, 遗传算法

Abstract: As the throughput grows, so does the total number of containers stored in the container yard, and the lack of yard space becomes a problem. Since the actual arrival time of the external container truck often deviates from its appointment time, this may conflict with the original pick-up plan, resulting in terminal congestion, low work efficiency, and reduced customer satisfaction. Therefore, how to effectively deal with the uncertainty of the arrival time of external container trucks has become one of the difficult issues in research. At present, the first-come-first-served service strategy is usually adopted when the external container truck pick-up operation is used. There are only two situations when the container truck deviates from the appointment time, one is that the container truck arrives at the port too early, and the container truck that arrives first according to the first-come-first-served service strategy will be given priority to pick up the container. However, if the container picked up by the container that arrives first has many blocked containers on it, the relocation operation will incur additional costs, which may lead to an increase in the total cost. The other one is, if the target container is located on the top layer of the bay, according to the first-come-first-served service strategy, the container truck can only wait for the pick-up, which will incur a certain waiting cost, and may also incur the cost of turning over the container when the container is removed when other container trucks pick up the container.In the yard, if container trucks do not arrive on time, they will cause congestion in the yard and pollute the environment.
This paper proposes a dynamic adjustment strategy(FCDS strategy) for the order of picking up containers considering weight and time difference. The aim is to minimize costs. A discriminant formula for deciding whether to start picking up containers immediately for external container trucks that arrive at container yard at the time of departure from the appointment time is proposed. In order to address the problem, a container handling scheduling model under the random arrival time of trucks is built to minimize the total cost when picking up containers. The genetic algorithm is used to solve the model.Finally, in order to prove the effectiveness of the strategy proposed in this paper, it is compared with the first-come-first-served pick-up strategy commonly used in external container trucks, and four sets of experiments are designed.The four groups of experiments are carried out under different disturbances, and the arrival scenarios of container trucks are randomly generated, and the relocating cost and waiting cost of the two strategies are calculated. This article mainly considers the impact of these two costs, which constitute the total cost incurred when the outer truck suitcase is collected.
Based on the experimental data, we draw a plot to compare the advantages and disadvantages of the two strategies. The results show that the two strategies have obvious differences in the same situation, and the greater the disturbance, the more obvious the difference. The longer the departure time of the container truck, the better the FCDS strategy, because the FCDS strategy is more flexible and can reasonably arrange the order of pick-up. Finally, the two strategies are compared using the expectation and variance of cost. Expectations can reflect the average of total costs, and variance reflects fluctuations in costs. Numerical experiment results show that compared with first-come-first-served strategy, this strategy can reduce cost and ensure cost stability in various scenarios.
Finally, in the case of the deviation of the external container trucks from the appointment time, a more flexible service strategy can be adopted to improve the work efficiency of the container yard, and the FCDS strategy has better stability in most scenarios, taking into account the needs of both the terminal and the customer, improving customer satisfaction, reducing the total cost, and making the external container more intelligent. In addition, good working order can reduce the environmental pollution of the port and promote the creation of a green port.

Key words: container terminal, delivery truck, retrieving container strategy, random arrival time, genetic algorithm