Improved STNModels and Heuristic Rules for Cooperative Scheduling in Automated Container Terminals

Improving the cooperative scheduling efficiency of equipment is the key for automated container terminals to copewith the development trend of large-scale ships. In order to improve the solution efficiency of the existing spacetimenetwork (STN) model for the cooperative scheduling problem of yard cranes (YCs) and automated guidedvehicles (AGVs) and extend its application scenarios, two improved STN models are proposed. The flow balanceconstraints in the original model are decomposed, and the trajectory constraints of YCs and AGVs are added toacquire the model STN_A. The coupling constraint in STN_A is updated, and buffer constraints are added toSTN_A so that themodel STN_B is built.As the size of the problem increases, the solution speed of CPLEX becomesthe bottleneck. So a heuristic method containing three groups of heuristic rules is designed to obtain a near-optimalsolution quickly. Experimental results showthat the computation time of STN_A is shortened by 49.47% on averageand the gap is reduced by 1.69% on average compared with the original model. The gap between the solution ofthe heuristic rules and the solution of CPLEX is less than 3.50%, and the solution time of the heuristic rules is onaverage 99.85% less than the solution time of CPLEX. Compared with STN_A, the computation time for solvingSTN_B increases by 58.93% on average.

Dynamic Scheduling and Path Planning of Automated Guided Vehicles in Automatic Container Terminal

The uninterrupted operation of the quay crane(QC)ensures that the large container ship can depart port within laytime,which effectively reduces the handling cost for the container terminal and ship owners.The QC waiting caused by automated guided vehicles(AGVs)delay in the uncertain environment can be alleviated by dynamic scheduling optimization.A dynamic scheduling process is introduced in this paper to solve the AGV scheduling and path planning problems,in which the scheduling scheme determines the starting and ending nodes of paths,and the choice of paths between nodes affects the scheduling of subsequent AGVs.This work proposes a two-stage mixed integer optimization model to minimize the transportation cost of AGVs under the constraint of laytime.A dynamic optimization algorithm,including the improved rule-based heuristic algorithm and the integration of the Dijkstra algorithm and the Q-Learning algorithm,is designed to solve the optimal AGV scheduling and path schemes.A new conflict avoidance strategy based on graph theory is also proposed to reduce the probability of path conflicts between AGVs.Numerical experiments are conducted to demonstrate the effectiveness of the proposed model and algorithm over existing methods.

Human Health Risk Assessment in Shahid Rajaee Container Terminal

As the ports play a prominent role in the national economy of the countries and a number of factors such as safety condition of the port and low rate or non-occurrence of accidents are greatly important for being selected as a destination for cargo owners to bring their vessels and cargo therein, giving due care to safety related issues in ports and harbors is among jurisdictional and sensitive duties of the authorities in ports and maritime areas. Enjoying some 3000 km of marine coastlines and more than 10 commercial ports throughout the country, Iran is no exception where its ports are responsible for cargo import and export. In this respect, container terminals are one of the high-risk areas in ports requiring extensive care of the pertaining authorities to take appropriate measures to maintain safety standard there. One of the significant methods and techniques for the risk assessment is P&HRAM as to the containers terminals. This method has been employed in this research taking into account the operation attributes of the works in ports and harbors. This method provided appropriate answers to the research questions in that it was predicted that the great part of the activities in container terminal poses a higher risk from human perspective than expected requiring some measures to be taken to mitigate the risks to a tolerable level. This research was conducted and the results demonstrated that more than 75% of the risks in container terminals are higher than acceptable level about which some measures were taken and the risks were reduced to 100% lower than tolerable level.

Dalian Container Terminal for 21st Century

Year of 1999 is the year of 50th anniversary of the founding of the People’s Republic of China, and 100th anniversary of the founding of Dalian City and port of Dalian. This year, Dalian Container Terminal Co. Ltd. (DCT) will also celebrate its 3rd anniversary of founding. On behalf of all DCT staff, I would llke to express our gratitude to all the friends and our business patroness. DCT is a joint venture between PSA Corporations and Port of Dalian Authority and commenced perations on July 1, 1996. In the past three years, with support from relevant communities, DCT has been growing up gradually. Recently, DCT was awarded the "Best Container Terminal Operator" in 13th Asian Freight Industry Awards, and ranked 11th in Asian Ports in terms of cargo volumes handled. DCT is the only Chinese Mainland port to achieve the honor.

Energy-aware Integrated Scheduling for Container Terminals with Conflict-free AGVs

For automated container terminals,the effective integrated scheduling of different kinds of equipment such as quay cranes(QCs),automated guided vehicles(AGVs),and yard cranes(YCs)is of great significance in reducing energy consumption and achieving sustainable development.Aiming at the joint scheduling of AGVs and YCs with consideration of conflict-free path planning for AGVs as well as capacity constraints on AGV-mate which is also called buffer bracket in blocks,a mixed integer programming model is established to minimize the energy consumption of AGVs and YCs for the given loading/unloading task.A solution method based on a novel bi-level genetic algorithm(BGA),in which the outer and the inner layer search the optimal dispatching strategy for QCs and YCs,respectively,is designed.The validity of the model and the algorithm is verified by simulation experiments,which take the Port of Qingdao as an example and the performance under different conflicting resolution strategies is compared.The results show that,for the given task,the proposed solution to conflict-free path and the schedule provided by the algorithm can complete the task with minimum energy consumption without loss of AGVs utilization,and the number of AGV-mates should be adjusted according to the task rather than keeping unchanged.Comparison results indicate that our proposed approach could efficiently find solutions within 6%optimality gaps.Energy consumption is dropped by an average of 15%.

Distributed framework for yard planning in container terminals

This study discusses a yard planning system,which considers various resources such as storage space,yard cranes,and traffic areas in container terminals.The system is based on the function for estimating resource requirements of yard plans.For a given yard plan,the proposed system allows planners to check the feasibility of the plan which requires a certain amount of workload of resources in related blocks during a planning horizon.The yard planning system in this study is aimed at balancing workloads among the blocks and providing the ability to modify current yard plans by detecting blocks and periods with overloaded workloads.The system implements its planning function in a distributed manner in which planners construct yard plans under their individual control and send and receive only limited necessary information for the negotiation.

SIMULATION, ANALYSIS AND OPTIMIZATION OF CONTAINER TERMINALS PROCESSES

The freight logistics includes all the processes needed to supply industry,retailers and wholesalers and final customers with goods.Such processes generate a flow of goods that,in the global supply chain,mainly relies on the activities carried out within worldwide container terminals.In this paper,the authors present a simulation model of a real container terminal.After some preliminary analyses,the simulation model is first used with Design of Experiments and Analysis of Variance to investigate the effects of different resources allocations(i.e.,number of forklifts and tractors)and some parameters(i.e.,inter-arrival times,container unloading time)on the container terminal performances in terms of total number of handled containers per day.Then,based on the results achieved through the Design of Experiments and Analysis of Variance,the simulation model is used with genetic algorithms to carry out a range allocation optimization on berth assignment to incoming ships and number of tractors serving each quay crane.The aim of the optimization is the minimization of the average time spent by each ship in the port area(decreasing,as consequence,costs and increasing service level provided to final customers).

A Decision Support Method for Truck Scheduling and Storage Allocation Problem at Container

Truck scheduling and storage allocation, as two separate subproblems in port operations, have been deeply studied in past decades. However, from the operational point of view, they are highly interdependent. Storage allocation for import containers has to balance the travel time and queuing time of each container in yard. This paper proposed an integer programming model handling these two problems as a whole. The objective of this model is to reduce congestion and waiting time of container trucks in the terminal so as to decrease the makespan of discharging containers. Due to the inherent complexity of the prob-lem, a genetic algorithm and a greedy heuristic algorithm are designed to attain near optimal solutions. It shows that the heuristic algorithm can achieve the optimal solution for small-scale problems. The solutions of small-and large-scale problems obtained from the heuristic algorithm are better than those from the genetic algorithm.

REGIONAL CONTAINER PORT COMPETITION IN A DUAL GATEWAY-PORT SYSTEM

Many ocean transportation hub systems consist of two container ports that share the container handling business in the area. The container flow passing through a port is the main measurement of the port＇s competitiveness. In this paper we adopt a Hotelling model to study the container port competition in a so-called ＂dual gateway-port system＂. The system contains two ports and two terminals, one belonging to each port. The two governments in which the two ports are located compete on cargo fees and the two terminals determine service price and service quality. We study two models with different levels of competition between the terminals. In the ftrst model, the two terminals are owned by two different operators and in the second model, the two terminals are centralized under one operator. The second model exists in practice but is not well studied in the literature. We derive the cargo fee, terminal service price, and service quality equilibria for these two models. We investigate the competition outcome sensitivity with a numerical study. The numerical results reveal that governments prefer terminals to compete with each other. If the terminals do not have competitive advantages in their service quality, then terminal centralization brings more profits to the terminal operator than the competition case.

AN ANT COLONY ALGORITHM FOR YARD TRUCK SCHEDULING AND YARD LOCATION ASSIGNMENT PROBLEMS WITH PRECEDENCE CONSTRAINTS

This paper examines the yard truck scheduling,the yard location assignment for discharging containers,and the quay crane scheduling in container terminals.Taking into account the practical situation,we paid special attention to the loading and discharging precedence relationships between containers in the quay crane operations.A Mixed Integer Program（MIP） model is constructed,and a two-stage heuristic algorithm is proposed.In the first stage an Ant Colony Optimization（ACO） algorithm is employed to generate the yard location assignment for discharging containers.In the second stage,the integration of the yard truck scheduling and the quay crane scheduling is a flexible job shop problem,and an efficient greedy algorithm and a local search algorithm are proposed. Extensive numerical experiments are conducted to test the performance of the proposed algorithms.

A LAGRANGIAN RELAXATION-BASED ALGORITHM FOR THE ALLOCATION OF YARD CRANES FOR YARD ACTIVITIES WITH DIFFERENT PRIORITIES

This paper proposes a mixed integer programming model for the allocation of rail mounted gantry cranes for four basic yard activities with different priorities. The model pays special attention to the typical features of this kind of gantry cranes, such as a restricted traveling range and a limited number of adjustments during loading and discharging operations. In contrast to most of the literature dealing with these four yard activities individually, this paper models them into an integrated problem, whose computational complexity is proved to be NP-hard. We are therefore motivated to develop a Lagrangian relaxation-based heuristic to solve the problem. We compare the proposed heuristic with the branch-and-bound method that uses commercial software packages. Extensive computational results show that the proposed heuristic achieves competitive solution qualities for solving the tested problems.