Design And Optimization Of Multimodal Hub And Spoke Network Considering Environmental Benefits

With the introduction of the new development concept and the carbon peaking and carbon neutrality goals,the freight transport industry,as a significant contributor to carbon emissions in the transport industry,will play an active role in promoting society to be more sustainable.Thus,driven by both the social responsibility of emission reduction and the mandatory carbon emission reduction policy,it is important for freight transport enterprises to achieve a balanced coordination between cost and emission on the basis of satisfying transportation demand.Therefore,this thesis takes the feasible policy of carbon emission reduction into account,based on the hub-and-spoke network transport mode with scale effect,combined with the multimodal transport strategy with emission reduction potential,and conducts research on the design and optimization of multimodal hub-and-spoke network for freight transport enterprises considering environmental benefits.The main work of this thesis is as follows.Firstly,this thesis reviews the literature at home and abroad from two aspects,namely,the low-carbon multimodal hub-and-spoke network design and optimization model considering environmental benefits,and the algorithms for solving singleobjective and multi-objective optimization models.The above work provides the theoretical basis for the development and solution of the multimodal hub-and-spoke network design and optimization model considering environmental benefits.Secondly,the definition and characteristics of multimodal hub-and-spoke network are introduced.It also deconstructs and quantifies the factors influencing the design and optimization of multimodal hub-and-spoke network,such as carbon emission reduction policy,scale effect,transportation mode selection,and network cost,to strengthen the ability of the multimodal hub-and-spoke network design and optimization model constructed in this thesis to portray the real world,which can enhance the application value of this research.Subsequently,the cost measurement model based on transportation paths and the carbon emission measurement model based on network nodes are constructed by combining the identified key factors and quantitative characteristics of different transportation processes.Based on the above models,multimodal hub-and-spoke network design and optimization models considering environmental benefits are constructed based on the demonstration of the characteristics of different carbon reduction policies.In the mandatory carbon emission reduction stage,a social responsibility-oriented multimodal hub-and-spoke network design and optimization model is constructed with the objective of minimizing economic cost and carbon emission.In the carbon trade stage,a singleobjective cost-oriented multimodal hub-and-spoke network design and optimization model is constructed with the objective of minimizing the comprehensive economic cost by coupling the economic cost,carbon trading cost,and benefit.The above models provide theoretical support for practical applications.Then,by constructing an index system for evaluating the competitiveness of hubs in multimodal hubs and spokes networks,the hub sites are identified.Based on the hub location results,for the multi-objective model,the normalized congestion calculation method is proposed to improve the NSGA-II algorithm to find the initial feasible solution,and then to improve the accuracy of the Pareto solution set.The initial clustering center determination method based on the equipartition method is proposed to improve the KMeans algorithm to cluster the feasible solution,Finally the ILS algorithm is coupled to re-optimize the feasible solution clustering representatives.In order to avoid late solution mutations,the genetic algorithm using the non-coherent mutation method is proposed to for solving the single-objective model.Finally,the model proposed in this thesis is applied to solve different network optimization schemes for W cargo transportation company in Henan,China,where the network structure,economic cost and carbon emission are compared and analyzed.The accuracy and stability of the model are also verified by the sensitivity analysis on carbon trading price and number of hubs,respectively.