| To further implement the policy implementation and respond to the policy goal of "carbon peaking and carbon neutralization","the Fourteenth Five Year Development Plan for Green Transportation" proposes to strive to form a green low-carbon production mode in the field of transportation,improve the average annual growth rate of container rail water intermodal transportation,and gradually realize the construction of a powerful transportation country.In addition,the goods will be interfered with by various uncertain factors in the actual transportation process.Considering the randomness and fuzziness of the uncertain factors,and taking into account the greenhouse gas emission,it is of far-reaching significance to study the empty container transportation and route optimization of the container sea-rail combined transportation system.To meet the demand for empty containers in container terminals and ports and establish a green and sustainable transportation system,the multi-schedule empty container transportation problem was studied based on the lowest total operating cost and the least carbon and sulfur emissions.Considering the uncertainty of empty container supply and demand,the trapezoidal fuzzy variable is used for processing,and the fuzzy chance constraint programming model is established.After the model is transformed into a definite form,the NSGA-Ⅱ algorithm is used to solve it,and the Pareto solution set of the transportation scheme is obtained.The chart analysis shows that transportation and handling cost are the main components of the total operating cost,and the total operating cost and carbon and sulfur emissions under the sea rail combined transport mode are 18.92% and 14.17% better than those of pure railway transport respectively.In order to improve the utilization efficiency of the carriers and save the storage space of the container handling station,this paper also integrates the mode of mixed transportation of foldable containers and standard containers.The analysis of the results shows that the purchase cost is the key factor affecting the use of collapsible containers,and after appropriately reducing the purchase cost of collapsible containers,the mixed transport organization mode can achieve lower total operating costs than transporting full standard containers.At the same time,a certain proportion of foldable containers can reduce carbon and sulfur emissions.For the path optimization of containerized sea-rail transportation,considering the fluctuation of railroad transportation time,container port transit time,and ocean transportation time,a multi-objective stochastic chance-constrained planning model with the lowest total transportation cost and the lowest carbon emission is constructed.According to the sufficiency of cargo sources,two transportation organization modes are selected: one-stop direct transportation mode and intermediate transfer transportation mode.Train and ocean arrival times are introduced into the constraint conditions,stochastic planning and interval planning are selected to express uncertain transportation time and transit loading time.After converting the uncertainty constraint into a linear constraint using the knowledge of uncertainty and probability theory related theories,the NSGA-II algorithm with improved initialized population and elite selection operator is used to solve the problem.The Pareto solution set under different transportation organization modes is obtained by taking the optimization of container cargo outlet route from Xi’an to Los Angeles as the case background.The comparative analysis of the results is as follows:(i)The transportation cost,carbon emission and convergence algebra are significantly optimized after the algorithm improvement,and the speed of the algorithm solution is greatly improved.(ii)The transportation costs and delivery punctuality in the deterministic environment are slightly lower compared to the uncertain environment,the range of relative deviations in transportation costs is consistent with transportation reality.(iii)The sub objective values of multiple solutions of multi-objective programming are between the objective values of single objective programming,which is more consistent with the reality than single objective programming.Finally,sensitivity analysis is applied to analyze the impact of rail,ocean transportation confidence levels and transit time impact factors on total transportation costs and cargo delivery punctuality.Higher confidence level will increase the total transportation cost of goods and increase the influence factor of transit time,and the delivery punctuality of goods will be reduced accordingly.In summary,the model and algorithm proposed in this paper are of good practical use. |
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