Sustainable Urban Logistics Distribution Network Planning with Carbon Tax

Round 1

Reviewer 1 Report

First of all, I appreciate the opportunity to review the paper Sustainable Urban Logistics Distribution Network Planning with Carbon Tax.   The topic is very important and actual. Comments are below:

·        The abstract should be strengthened.

·        The last paragraph in the introduction section should be a short methodology/structure of the paper (several sentences for each section). This is missing.

·        The question is whether this model could be applied to complex real systems. 

·        The separate section Practical and theoretical implications (or Discussion) is missing. This confirms the lack of scientific and practical contributions.

·        The conclusion section is written very unprofessionally and there are no concluding remarks or output. The authors will have to demonstrate the impact and insights of the research. The authors need to clearly provide several solid future research directions (this confirms a bad relationship with the gaps in the literature). Future research directions are missing.

·        Limitations of this research are also missing.

·        Figure 1 is very trivial. Logistics distribution networks are more complex with numerous participants. It is also contradictory to hypotheses H1 and H2.

·        Scientific contributions of the paper are questionable. 

Author Response

1.The abstract should be strengthened.
Thanks. Yes, it has been strenthened and main contributions or findings are added here.
2.The last paragraph in the introduction section should be a short methodology/structure of the paper. This is missing.
Thanks. A new paragraph has been added to introduce the technical route and structure of the paper. 
3.The question is whether this model could be applied to complex real systems. 
Thanks for your comments. Concerning this point, we have discussed in the discussion section and the conclusion section.  
4.The separate section Practical and theoretical implications (or Discussion) is missing. This confirms the lack of scientific and practical contributions.
Thank you for your advice. A new section, Discussion is given here to interpret the research results, meanwhile, as you pointed out, to introduce the contributions of the article both in theory and in practice. 
5.The conclusion section is written very unprofessionally and there are no concluding remarks or output. The authors will have to demonstrate the impact and insights of the research. The authors need to clearly provide several solid future research directions (this confirms a bad relationship with the gaps in the literature). Future research directions are missing.
Thanks. Yes, we have rewritten the last conclusion section. In this section, we more explicitly summarize the research conclusions of this paper. And we supplement three research shortcomings and propose two much promising research directions for potential readers of this article.  
6. Limitations of this research are also missing.
Thanks. We have rewritten the conclusion with updated introdution of the research limitations. 

7.Figure 1 is very trivial. Logistics distribution networks are more complex with numerous participants. It is also contradictory to hypotheses H1 and H2.
Thank you for your reminders. We redraw the figure 1 and there are mainly two changes. First, it can show the compelx structure of the logistics network, especially the full connection between neibouring entities. Second, we mark the decision variables in the figure for references in the following model formulation process. 
8. Scientific contributions of the paper are questionable. 
Thanks for your reminding. We have summarized main contriutions and discussed the theoretical and practical uses of the research results. 

Reviewer 2 Report

The authors formulated a mathematical programming model to simulate the decisions of the selection of alternative distribution centers and the transport quantity from the logistics hubs to the selected distribution centers under different carbon tax scenarios. The motivation of the research is clear. I suggest the following revisions to improve the quality of the manuscript:

1.     The so-called “bi-objective two-level…model” is arguable. Two-level programming model is a terminology to describe a model involves the problem of upper level decision and lower level decision with reaction function. The decision maker of upper level and lower level are different and interactive. The logistics decisions in this manuscript involve only one decision maker or one decision unit. Therefore, the term “two-level” should be eliminated.

2.     Multiple objective programming model solves the conflict between different objectives. A set of non-inferior solutions are generated, and the decision maker make decision through trade-off analysis. The authors simplifies the solution process by adding two objectives together (equation 14). This means the weightings between TC and CE are the same. The solution only represents one of the non-inferior solutions. This solution does not necessarily insure meets the preferences of the decision maker. Therefore, the authors should indicate the require assumptions before proceeding the solution process.

3.     The presentation of figure 1 had better revised to meet the meaning of the decision variables under the assumed supply chain.

Author Response

1.     The so-called “bi-objective two-level…model” is arguable. Two-level programming model is a terminology to describe a model involves the problem of upper level decision and lower level decision with reaction function. The decision maker of upper level and lower level are different and interactive. The logistics decisions in this manuscript involve only one decision maker or one decision unit. Therefore, the term “two-level” should be eliminated.
Thank you. That's right the two-level model is the common name for two level programmings. The word has been discarded in the article. 
2.     Multiple objective programming model solves the conflict between different objectives. A set of non-inferior solutions are generated, and the decision maker make decision through trade-off analysis. The authors simplifies the solution process by adding two objectives together (equation 14). This means the weightings between TC and CE are the same. The solution only represents one of the non-inferior solutions. This solution does not necessarily insure meets the preferences of the decision maker. Therefore, the authors should indicate the require assumptions before proceeding the solution process.
Thank you very much and we fully understand your meaning. We know that the two objectives are not in sync and a Pareto optimal surface shall be given if no further weight info. is given to them. The characteristic of this programming is that, through the carbon tax mechanism, the amount of carbon dioxide emissions can be converted and internalized into a type of the production costs  for logistics operators, so that it can be perfectly integrated with another operating cost target. So the total cost is still reasonable. Thank you again for the reminder.
3.  The presentation of figure 1 had better revised to meet the meaning of the decision variables under the assumed supply chain.
Thanks and we have supplemented the info. related to decision variables in the figure 1. Meanwhile, we redraw the figure 1 to show more clearly the relations among different entities in the network.  

Round 2

Reviewer 1 Report

The paper should be accepted for publication.