Research On Multi-objective Two-stage Optimization For Port Yard Trailers Routing Under Loading-and-unloading Cooperation

With the continuous downturn of the global economy,as the main component of the port economy,how to make port enterprises strong will become the eternal theme of its sustainable development while making them bigger.From the perspectiv e of global por t competition pattern,Chinese ports rank top in the world in terms of operational efficiency and scale,but this is mainly due to the investment of a lar ge number of infrastructure facilities,the vast geographical area and the advantage of China’s cheap labor force.From the perspective of the utilization efficiency of port resources,com pared with So uth Korea,Singapore and other countries,they are not s uperior.That is to say,China’s ports still have problems such as low utilization rate of facilities,high vacancy rate and poor unit efficiency.However,with the global economic downturn and the rise of trade protectionism,as well as the gradual disappearance of domestic labor dividends,Chinese ports will face in creasing pressure in operating efficiency.Considering the complexity and coupling of the production and opera tion of the container terminal,as well as the universality and key of the optimization of the path of container trucks,solving the problem of the optimization of the path of container trucks will hold the nose of the overall optimization of the container terminal.Based on the above background,this paper analyzes and summarizes the research on the optimization of the path of container trucks in the academic and business circles at home and abroad,it is found that the goal of card path optimization mainly includes the shortest distance,the smallest time and the lowest cos t(including environmental protection cost).However,in the actual application process of an enterprise,considering different application scenarios,some only consider a single element,some may consider a double element,and some need to consider all three elements,or even the combination of multiple elements.In order to maximum cover multiple scenarios,this paper selects the typical single-element target optimal,dual-element target optimal and three-elem ent target optimal as the application scenario.From the perspective of loading and unloading synergy,the two-stage path optimization is innovatively proposed.the first stage solves the problem of the number of loading and unloading paths under the single-object optimal situation;on the basis of the first stage,the second stage solves the problem of refinement of specific vehicles and paths and their sequence through tar get re-optimization,ensuring that the sch eme can be "used immediately".The specific research content and work are as follows:(1)Introduced the m anagement characteristics of container ports,in cluding the spatial layout of container ports,main equipment,scheduling mode,container truck path optimization and target management.Analyze the relevant theories of container port truck m anagement,define the connotation of related concepts,and analyze the current status and existing problems in China.(2)The travel distance of container trucks is an important factor affecting cost,and it is also the main optimization target of the business community and academia.This chapter only considers the single element of distance,and a two-stage path optimization model considering the double-target of container truck driving distance and no-load distance under the cooperation of loading and unloading is constructed.In th e first stage,the path o ptimization model of container truck is established with the minimum total distance of container truck as the objective function.Taking the solution result of the firs t-stage model as the known input,taking the transportation process of each path as a tas k,and aiming at the m inimum no-load distance between container truck tasks,the second-stag e container truck path optimization model was established.(3)Based on the optimization of single-factor target container truck path,this chapter takes the optimization of tim e and cost dual-factor target as an exam ple.The two-stage path optimization model considering container truck fuel consumption and tim e double target is constructed.Among them,the first stage is based on the research on the no-load and full-load path optimization of container trucks.Considering the dif ference between the fuel cost of container trucks at full load and no-load,the container truc k path optimization model with minimum fuel cost is constructed.The second stage is in the first stage.Based on the one-stage research,the container truck path optimization model with minimal working time is constructed.(4)The determination of the loading and unloading capacity of the container port is only a theoretical situation for the port.For the daily dispatch of the container port,the daily loading and unloading capacity of the container is us ually uncertain.Based on the above research.Considering cost,distance and time,a two-stage optimization model is constructed.(5)Based on the research on path optimization in this paper,the main problems existing in the container truck dispatching and m anagement of container ship s are analy zed,and effective countermeasures and suggestions for container port management are put forward for the existing problems.