Integrated Scheduling Modeling Of Automated Container Terminals With Buffer System

Under the background of the prosperity and development of shipping and economic globalization,the construction and development of automated container terminals has become the forefront theme in the study and construction of the smart port.As automated container terminal is a complex system composed of multi-level ‘storage-transfer-buffer’ subsystems,the loading,unloading and handling operations of import/export containers are completed by multiple terminal equipment.As an important part of container terminal operation system,the buffer system such as buffer zone and buffer lane plays an important role in the above operations.In order to improve the operational efficiency of automated container terminals under the constraint of limited resources,by considering the configuration and function of buffer system and other factors,this thesis propose the problem of modeling the integrated scheduling optimization of automated container terminals with buffer system in according to the current research on the integrated scheduling problem of container terminals.In this thesis,the constraints of buffer facilities are gradually added to the integrated scheduling optimization problem from local to whole,as well as,from single to multiple.Three integrated scheduling problems of automatic container terminals with single buffer zone,multi-buffer zones and multi-buffer systems are studied comprehensively and systematically.The key contents in this thesis consisted of following three parts:(1)Modelling the integrated scheduling problem with single buffer zone at an automated container terminalAt automated container terminals equipped with automated lifting vehicles,the block and apron buffer zones are installed to temporarily store the containers transferred between the upstream and downstream devices.In order to quantify the buffer capability of each type of buffer facilities in integrated scheduling system,we incorporate the function and constraint of the selected buffer zone into the integrated scheduling problem,and develop two problems of integrated scheduling of automated stacking cranes(ASCs)and automated lifting vehicles(ALVs)with a limited block buffer capacity and integrated scheduling of quay cranes(QCs)and ALVs with a limited apron buffer capacity,respectively.For each problem,the corresponding integrated scheduling model is formulated to minimize the makespan of all jobs.Considering the complexity of each problem,an algorithm framework of "simulation/heuristic + meta-heuristic algorithm" is proposed to solve the large-scale instances according to the operation procedure of integrated scheduling and the full-buffer rule.(2)Modelling the integrated scheduling problem with multi-buffer zones at an automated container terminalAt automated container terminals equipped with automated lifting vehicles,referring to the modeling method of integrated scheduling problem considering single buffer zone,we discuss the quantification method of the overall buffer capacity of the apron and block buffer zones in the integrated scheduling system,incorporate the limited capacity constraints of the block and apron buffer zones into the corresponding integrated scheduling problem,and then propose the problem of integrated scheduling of ASCs,ALVs and QCs with limited apron and block buffer zones’ capacities.Considering the complexity of the problem,an algorithm framework of "simulation/heuristic + meta-heuristic algorithm" is proposed to solve the large-scale instances according to the device assignment and scheduling strategies and the proposed model.(3)Modelling the integrated scheduling problem with multi-buffer systems at an automated container terminalAt automated container terminals equipped with automated guided vehicles(AGVs),the transferring operation of containers between QCs and AGVs should satisfy the synchronization in time and spatial dimensions.By setting the buffer lanes around QCs to park the AGVs with containers,the scheduling time window for AGVs is extended,and then the cooperative scheduling process of QCs and AGVs is optimized to realize their time-spatial synchronization.Based on this,in order to quantify the buffer capability of a container terminal containing the buffer lanes and the block buffer zones,this thesis proposes an automated container terminal integrated scheduling problem considering two constraints of the assignment of parking positions in the buffer lanes and the limited block buffer capacity,and this realizes the expansion from the equipment integration to the buffer system integration.In this thesis,a model of this problem is formulated and an algorithm framework of "simulation/heuristic + meta-heuristic algorithm" is designed to solve the large-scale instances.Based on the modeling method of the above contents,combined with the results and analysis of the numerical experiments,the following main conclusions related to the buffer system are listed: 1)the buffer zone plays an important role in the integrated scheduling process of automated container terminals,and the description form of its limited capacity constraint in the model is related to the selected time node for time window;2)the description form of limited buffer capacity constraint in the algorithm is related to the assigning and scheduling strategies of upstream and downstream equipment;3)the buffer lane can reorder the AGVs carrying containers to meet the QC loading sequence,which can improve the flexibility of AGV and ASC operations.The innovations of this thesis lay in 1)considering the constraints of multibuffer systems in the integrated scheduling problem of automated container terminals enriches the scheduling theory for container terminals;2)the modeling method for formulating the integrated scheduling optimization of automated container terminals with the buffer system;and 3)the optimization algorithm for solving the integrated scheduling problem of automated container terminals with the buffer system according to the operation mechanism of buffer system.The limitations of this thesis include 1)that the proposed algorithm cannot solve the optimal solution of the large-size case of the studied problems in a short time,2)that our study on the real-time scheduling and simulation of container terminal equipment is insufficient,and 3)that the study of integrated scheduling problem with buffer systems still needs to be in-depth.