Cold Chain Distribution Route Optimization for Mixed Vehicle Types of Fresh Agricultural Products Considering Carbon Emissions: A Study Based on a Survey in China

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Must improve:

1. key words - use word not terms (for example, distribution, vehicle...)

2. Survey period of 15 days is not enough representative for relevant results!

3. "State of art" of article, which is objective value added of article, better explained in chapters, is it new methodology or?

Author Response

Dear reviewer,

Thank you for your comments concerning our manuscript. These comments have been very helpful in improving our paper. Each comment has been carefully studied, and the paper has been carefully revised accordingly. The revised portions of the paper are marked in red.The detailed revisions made in response to your comments are as follows. 

1) Reviewer Comment: key words - use word not terms (for example, distribution, vehicle...)

Reply: Thank you very much for your suggestion. According to the suggestion, we have modified the keywords as follows:

Keywords: distribution; vehicle; carbon; optimization

2) Reviewer Comment: Survey period of 15 days is not enough representative for relevant results!

Reply: Thank you for your comments. In the process of research, in order to understand the cold chain distribution route planning of fresh agricultural products, we carried out a survey on the basis of literature analysis, and the investigation content referred to the research results of the literature. In other words, the relevant results are synthesized by combining literature analysis and investigation. We have made a supplementary explanation in the article. In addition, because the survey was conducted in China, we have amended the title of the article to reflect this fact. The modifications are as follows:

Cold chain distribution route optimization for mixed vehicle types of fresh agricultural products considering carbon emissions：A study based on a survey in China

3.1.1. Investigation Plan

Through the analysis of existing literature, it is found that cost minimization is one of the main goals of cold chain distribution route optimization for fresh agricultural products. Almost all of the research is about how to reduce costs, but different studies focus on different types of costs, among which fixed cost and transportation cost are generally considered, and some involve penalty costs, refrigeration costs, cargo damage costs, etc. Then, what costs are considered by enterprises in reality, and what costs are worthy of attention. This study conducted a survey on cold chain logistics companies of fresh agricultural products in view of these problems. At the same time, through the investigation to understand the actual situation of enterprises and decision-making methods.

Regarding the goal of cold chain distribution route planning, the survey mainly understands the cost considered by the enterprise. The surveyors know what aspects of costs are mainly considered by enterprises in cost calculation through inquiry, and record them. When the interviewees could not answer, the researchers would remind them based on the results of the literature analysis, such as whether the cost of carbon emissions was considered.

3) Reviewer Comment: "State of art" of article, which is objective value added of article, better explained in chapters, is it new methodology or?

Reply: Thank you very much for your suggestion. As you suggest, we have highlighted the differences and novelty of the paper in different sections of the article. The main difference between this paper and the existing studies is the research content, which comprehensively considers the time window, carbon emission and mixed vehicle types to establish the cold chain distribution optimization model of fresh agricultural products. The purpose of establishing the model is to achieve both economic and environmental benefits and promote the sustainable development of cold chain logistics of fresh agricultural products. First of all, we added a table in the literature review section for literature comparison, from which we can better find the differences between this paper and existing studies. Secondly, we added a "discussion" section before the "conclusions" to emphasize the research characteristics of this paper again. In addition, we have explained the differences and significance of the article many times in the third chapter. The changes made are listed below.

To sum up, there are many research results on cold chain distribution route optimization, but the focus of attention is different. The comparison of existing studies is shown in Table 1, depending on whether they are specific to fresh agricultural products, and whether time windows, carbon emissions, and multiple vehicle types are considered. It can be seen that time window constraints are basically considered, some studies specifically combine the characteristics of fresh agricultural products, carbon emission factors have attracted attention, and there are relatively few studies on multiple vehicle types. Studies that consider all four factors at the same time are lacking.

Table 1. Comparison of existing studies on cold chain distribution routes.

Document number	Fresh agricultural products	Time window	Carbon emission	Multiple vehicle types
1-4	√
5-7		√
8-11	√	√
12-13			√
14-23		√	√
24-27	√	√	√
28-32				√
33-35	√	√		√
36		√	√	√

Note: A "√" indicates that this factor was taken into account in the relevant literature.

As the demand for cold chain distribution of fresh agricultural products is strong, and carbon emission and distribution of various vehicle types are realistic problems that have to be considered, this paper intends to comprehensively consider the four factors mentioned above, and explore the optimization of cold chain distribution path of mixed vehicle types of fresh agricultural products considering carbon emission, in order to provide decision-making reference for the sustainable development of cold chain of agricultural products. The main features of this study are as follows: (1) Considering the time window constraint in the optimization of the distribution path. Maximize customer requirements for delivery time and improve customer satisfaction. (2) Consider the carbon emissions in the cold chain distribution of fresh agricultural products. Pursue economic benefits while improving environmental benefits. (3) Consider the impact of the distribution of multiple types of vehicles. Rationally allocate vehicle resources according to realistic conditions.

5. Discussion

Reasonable planning of cold chain logistics distribution route is an important measure to save logistics resources, reduce the impact on the environment, and promote the sustainable development of agricultural cold chain logistics. On the basis of field investigation, this paper establishes a new optimization model of cold chain distribution route for fresh agricultural products, and carries out an example analysis. The results show that:

(1) It is necessary and feasible for cold chain distribution route planning of fresh agricultural products to comprehensively consider factors such as carbon emissions and mixed vehicle types. In view of the high timeliness requirements and high energy consumption of cold chain distribution of fresh agricultural products, the planning of distribution routes should not only consider the constraints of the time window, but also consider how to rationally use vehicle resources, give play to the advantages of different types of vehicles, in order to reduce distribution costs and reduce carbon emissions. Compared with the decision-making model that considers a single or a few factors, the model that considers the time window, carbon emission and hybrid vehicle can better balance the economic and environmental benefits, and has better application value in the current realistic conditions.

(2) The optimal overall cost should be pursued in the cold chain distribution route planning of fresh agricultural products. Cold chain distribution process will produce a variety of costs, if only pay attention to one or two of the costs, may lead to the increase of other costs, affecting the overall operation effect. Therefore, when planning the distribution route, we should fully understand the possible costs, and pursue the minimum comprehensive cost. From the characteristics of cold chain distribution of fresh agricultural products, fixed cost, transportation cost, penalty cost, cargo loss cost, refrigeration cost and carbon emissions cost are components that can not be ignored, and should be comprehensively considered in decision-making.

(3) Genetic algorithm is an effective method to solve the cold chain distribution route optimization model of fresh agricultural products. There are many methods to solve mathematical models, and each has its own advantages. In this paper, genetic algorithm is chosen to solve the problem. From the algorithm design and practical application, the algorithm can explain the model decision thinking well and help find the optimal solution quickly, so it is an effective solution method. Of course, if the model is further optimized, genetic algorithms mixed with other methods can be tried to improve the ability to solve the problem.

Special thanks again for your suggestions.

Kind regards,

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Please see the enclosed file.

Comments for author File: Comments.pdf

Author Response

Dear reviewer,

Thank you for your comments concerning our manuscript. These comments have been very helpful in improving our paper. Each comment has been carefully studied, and the paper has been carefully revised accordingly. The revised portions of the paper are marked in red.The detailed revisions made in response to your comments are as follows. 

1) Reviewer Comment: The references are outdated. Please update them with more recent articles from the last few years.

Reply: Thank you very much for your comments. According to your suggestion, we have added 12 articles from the last three years to the literature review section, reflecting the latest research results in the field. Additional literature is listed below:

1. Yang, F.; Tao, F.M. A bi-objective optimization VRP model for cold chain logistics: Enhancing cost efficiency and customer satisfaction. Ieee Access. 2023, 11, 127043-127056.
2. Liu, Z.H.; Li, X.J. Optimization model of cold chain logistics delivery path based on genetic algorithm. Int J Ind Eng-Theory. 2024, 31(1), 152-169.
3. Wu, D.Q. ; Li, J.Y. ; Cui, J.Y. ; Hu, D. Research on the time-dependent vehicle routing problem for fresh agricultural products based on customer value. Agriculture-Basel. 2023, 13(3), 681.
4. Wang, W.J.; Wen, S.Z.; Gao, S.; Lin, P.Y. A multi-objective dynamic vehicle routing optimization for fresh product distribution: A case study of Shenzhen. Electron Res Arch. 2024, 32(4), 2897-2920.
5. Zhang, X.; Chen, H.Z.; Hao, Y.C.; Yuan, X.M. A low-carbon route optimization method for cold chain logistics considering traffic status in China. Comput Ind Eng. 2024, 193, 110304.
6. Yang, L.; Gao, Y.L.; Sun, Y.; Li, J. Two-phase hybrid search algorithm for time-dependent cold chain logistics route considering carbon emission and traffic congestion. Ieee Access, 2024, 12, 95128-95151.
7. Ma, Z.C. ; Zhang, J.; Wang, H.H.; Gao, S.C. Optimization of sustainable bi-objective cold-chain logistics route considering carbon emissions and customers' immediate demands in China. Sustainability-Basel. 2023, 15(7), 5946.
8. Yao, Q.; Zhu, S.J.; Li, Y.H. Green vehicle-routing problem of fresh agricultural products considering carbon emission. Int J Env Res Pub He. 2022, 19(14), 8675.
9. Feng, Q.; Zhao, G.; Li, W.J.; Shi, X.J. Distribution path optimization of fresh products in cold storage considering green costs. Buildings-Basel. 2023, 13(9), 2325.
10. Pérez-Lechuga, G.; Martínez-Sánchez, J.F.; Venegas-Martínez, F.; Madrid-Fernández, K.N. A routing model for the distribution of perishable food in a green cold chain. Mathematics-Basel. 2024, 12(2), 332.
11. Chen, Y.Y.; Chen, T.L.; Chiu, C.C.; Wu, Y.J. A multi-trip vehicle routing problem considering time windows and limited duration under a heterogeneous fleet and parking constraints in cold supply chain logistics. Transport Plan Techn. 2023, 46(3), 335-358.
12. Chen, W.R.; Zhang, D.Z.; Van Woensel, T.; Xu, G.M.; Guo, J. Green vehicle routing using mixed fleets for cold chain distribution. Expert Syst Appl. 2023, 233, 120979.

2) Reviewer Comment: On Page 4: please check the ranges of k and r .

Reply: Thank you very much for your suggestion. After careful checking, we have revised the ranges of k and r, that is, k=(1,2...,K), r=(1,2...,R).

3) Reviewer Comment: On Page 6, what is the meaning of M in equation (4).

Reply: Thank you very much for this comment. The M in equation (4) refers to the positive number of infinity, meaning that the delivery vehicle cannot arrive outside the maximum time range tolerated by the demand point, otherwise the penalty cost will be very high. We have made additional explanations in the paper.

If the driver of the vehicle does not deliver the goods within the time window acceptable to the customer, there will be a certain penalty cost. The penalty cost  at demand point i is a linear function of vehicle arrival time . There is a penalty if the vehicle arrives within the range of  and , while there is no penalty if it arrives within the time of , and the penalty value beyond the range of  is set to an infinite positive number M.

Special thanks again for your suggestions.

Kind regards,

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Improving the sustainability of cold supply chains is a relevant topic for many countries. The authors propose a methodology to optimize cold chain distribution routes for mixed vehicle types with fresh agricultural products for Chinese conditions.

My recommendations are as follows:

 

1. The authors investigate the problem of sustainable agricultural supply chains for the Chinese context. I propose to reflect this fact in the title of the article, indicating that the study is thematic.

2. To justify the relevance of the study, I suggest adding statistical data to the Introduction section.

3. I suggest that the literature review be organized into a separate section. I also suggest a table with a review of the main articles mentioned in the “Introduction” section, indicating the pros and cons of the existing approaches.

4. There are insufficient relevant references in the literature review. Please add more references for 2023 and 2024.

5. The structure of the paper needs to be reorganized. First, clearly describe the methodology (research steps and methods), the set of methods used and their clear alignment with research goals and achievement of these goals. Then present the case study.

6. It is not clear how the authors justify the cost types (Table 1). Why are seven types of costs chosen? (Fixed cost, Transparency cost, Penalty cost, etc.). What types of costs were considered at all? How was the selection made? Please explain for the readers.

7. What is the difference between your proposed method with other existing methods? You need to highlight the differences and novelty of the paper in the different parts of the paper. For example, in Section 3.3.

8. There is no discussion in the article. I suggest adding a Discussion section to compare the results with the available literature.

Author Response

Dear reviewer,

Thank you for your comments concerning our manuscript. These comments have been very helpful in improving our paper. Each comment has been carefully studied, and the paper has been carefully revised accordingly. The revised portions of the paper are marked in red.The detailed revisions made in response to your comments are as follows. 

1) Reviewer Comment: The authors investigate the problem of sustainable agricultural supply chains for the Chinese context. I propose to reflect this fact in the title of the article, indicating that the study is thematic.

Reply: Thank you very much for your suggestion. As you suggest, we have revised the title of the article as follows:

 Cold chain distribution route optimization for mixed vehicle types of fresh agricultural products considering carbon emissions：A study based on a survey in China

2) Reviewer Comment: To justify the relevance of the study, I suggest adding statistical data to the Introduction section.

Reply: Thank you very much for your suggestion. According to your suggestion, we have added some statistics in the introduction to supplement the explanation, and the added information is as follows：

1. Introduction

With the improvement of living standards and the upgrading of consumption structure, people's demand for fresh agricultural products is increasing, and the demand for cold chain distribution of fresh agricultural products is getting higher and higher. According to the “China Cold Chain Logistics Development Report (2024 edition)”, the total demand for cold chain logistics in China in 2023 is about 350 million tons, of which food (vegetables, fruits, meat, aquatic products and other fresh agricultural products) account for 90%. Due to the particularity of fresh agricultural products, in to ensure the freshness of agricultural products, it is necessary to maintain a low-temperature distribution environment and efficient distribution efficiency. Compared with ordinary logistics, the cooling demand of vehicles makes the cold chain distribution of fresh agricultural products consume more energy and produce more carbon dioxide (CO₂). Reductions of between 210 and 460 billion tonnes of CO₂ equivalent emissions can be delivered over the next four decades through actions to improve the cooling industry’s energy efficiency together with the transition to climate-friendly refrigerants, according to the Cooling Emissions and Policy Synthesis Report from the United Nations Environment Programme (UNEP) and the International Energy Agency (IEA). How to plan the distribution route scientifically and reasonably, so as to improve the distribution efficiency and satisfaction, and reduce the distribution cost and carbon emission, is a very noteworthy problem.

Due to the enhancement of environmental awareness, the use of new energy vehicles is becoming more and more widespread, and many fresh agricultural products cold chain logistics enterprises are in the stage of mixed-use such as gasoline refrigerated trucks and electric refrigerated trucks. China's “14th Five-Year Plan” Cold Chain Logistics Development Plan clearly points out that it is necessary to speed up the elimination of high-emission refrigerated vehicles, and encourage new or updated refrigerated vehicles to adopt new energy models in order to meet the needs of urban green distribution development. According to statistics on the website, 3,696 new energy refrigerated vehicles were sold in the first five months of 2024 in China (excluding exports), an increase of 310% compared with 2023. In this case, how to give full play to the advantages of various types of vehicles, use vehicles, and plan distribution routes reasonably, is a practical problem worth considering. In view of these, this paper comprehensively considers carbon emissions and mixed vehicle types and other factors to study the cold chain distribution route optimization of fresh agricultural products, so as to promote the high-quality development of agricultural cold chain logistics.

3) Reviewer Comment: I suggest that the literature review be organized into a separate section. I also suggest a table with a review of the main articles mentioned in the “Introduction” section, indicating the pros and cons of the existing approaches.

Reply: Thank you very much for your suggestion. As you suggest, we divided the literature review into a separate chapter, and we added a table to compare existing literature studies. The modification is as follows:

2. Literature Review

 

To sum up, there are many research results on cold chain distribution route optimization, but the focus of attention is different. The comparison of existing studies is shown in Table 1, depending on whether they are specific to fresh agricultural products, and whether time windows, carbon emissions, and multiple vehicle types are considered. It can be seen that time window constraints are basically considered, some studies specifically combine the characteristics of fresh agricultural products, carbon emission factors have attracted attention, and there are relatively few studies on multiple vehicle types. Studies that consider all four factors at the same time are lacking.

Table 1. Comparison of existing studies on cold chain distribution routes.

Document number	Fresh agricultural products	Time window	Carbon emission	Multiple vehicle types
1-4	√
5-7		√
8-11	√	√
12-13			√
14-23		√	√
24-27	√	√	√
28-32				√
33-35	√	√		√
36		√	√	√

Note: A "√" indicates that this factor was taken into account in the relevant literature.

4) Reviewer Comment: There are insufficient relevant references in the literature review. Please add more references for 2023 and 2024.

Reply: Thank you very much for your comments. According to your suggestion, we have added 12 articles from the last three years to the literature review section, reflecting the latest research results in the field. Additional literature is listed below:

1. Yang, F.; Tao, F.M. A bi-objective optimization VRP model for cold chain logistics: Enhancing cost efficiency and customer satisfaction. Ieee Access. 2023, 11, 127043-127056.
2. Liu, Z.H.; Li, X.J. Optimization model of cold chain logistics delivery path based on genetic algorithm. Int J Ind Eng-Theory. 2024, 31(1), 152-169.
3. Wu, D.Q. ; Li, J.Y. ; Cui, J.Y. ; Hu, D. Research on the time-dependent vehicle routing problem for fresh agricultural products based on customer value. Agriculture-Basel. 2023, 13(3), 681.
4. Wang, W.J.; Wen, S.Z.; Gao, S.; Lin, P.Y. A multi-objective dynamic vehicle routing optimization for fresh product distribution: A case study of Shenzhen. Electron Res Arch. 2024, 32(4), 2897-2920.
5. Zhang, X.; Chen, H.Z.; Hao, Y.C.; Yuan, X.M. A low-carbon route optimization method for cold chain logistics considering traffic status in China. Comput Ind Eng. 2024, 193, 110304.
6. Yang, L.; Gao, Y.L.; Sun, Y.; Li, J. Two-phase hybrid search algorithm for time-dependent cold chain logistics route considering carbon emission and traffic congestion. Ieee Access, 2024, 12, 95128-95151.
7. Ma, Z.C. ; Zhang, J.; Wang, H.H.; Gao, S.C. Optimization of sustainable bi-objective cold-chain logistics route considering carbon emissions and customers' immediate demands in China. Sustainability-Basel. 2023, 15(7), 5946.
8. Yao, Q.; Zhu, S.J.; Li, Y.H. Green vehicle-routing problem of fresh agricultural products considering carbon emission. Int J Env Res Pub He. 2022, 19(14), 8675.
9. Feng, Q.; Zhao, G.; Li, W.J.; Shi, X.J. Distribution path optimization of fresh products in cold storage considering green costs. Buildings-Basel. 2023, 13(9), 2325.
10. Pérez-Lechuga, G.; Martínez-Sánchez, J.F.; Venegas-Martínez, F.; Madrid-Fernández, K.N. A routing model for the distribution of perishable food in a green cold chain. Mathematics-Basel. 2024, 12(2), 332.
11. Chen, Y.Y.; Chen, T.L.; Chiu, C.C.; Wu, Y.J. A multi-trip vehicle routing problem considering time windows and limited duration under a heterogeneous fleet and parking constraints in cold supply chain logistics. Transport Plan Techn. 2023, 46(3), 335-358.
12. Chen, W.R.; Zhang, D.Z.; Van Woensel, T.; Xu, G.M.; Guo, J. Green vehicle routing using mixed fleets for cold chain distribution. Expert Syst Appl. 2023, 233, 120979.

 

5) Reviewer Comment: The structure of the paper needs to be reorganized. First, clearly describe the methodology (research steps and methods), the set of methods used and their clear alignment with research goals and achievement of these goals. Then present the case study.

Reply: Thank you very much for your suggestion. According to your suggestions, we have adjusted the structure of the paper, and the main framework after adjustment is: 1. Introduction. 2. Literature Review. 3. Method. 4. Example Analysis. 5. Discussion. 6. Conclusions. In addition, at the beginning of the third chapter, we described the methods and ideas used in the article as follows:

Establishing a mathematical model to guide decision making is a common method in distribution route planning. Based on the existing decision-making model, this paper intends to establish a new cold chain distribution route optimization model for fresh agricultural products by comprehensively considering factors such as time window, carbon emission and mixed vehicle types, and select a suitable solution algorithm. Since the factors and ideas considered in decision-making are reflected in the objective function and constraint conditions of the model, this paper, before establishing the model, mastered the core elements of cold chain distribution of fresh agricultural products through literature analysis and investigation, and provided a basis for setting the model's objectives and constraint conditions.

6) Reviewer Comment: It is not clear how the authors justify the cost types (Table 1). Why are seven types of costs chosen? (Fixed cost, Transparency cost, Penalty cost, etc.). What types of costs were considered at all? How was the selection made? Please explain for the readers.

Reply: Thank you very much for your suggestion. The original table 1 shows the results of the actual survey, i.e. the distribution costs considered by the surveyed companies. In accordance with your suggestion, in order to make it easier to understand, we have changed the expression of the table, indicating the cost considered by each company. At the same time, the source of the table data is explained in the text. The changes made are as follows:

Regarding the goal of cold chain distribution route planning, the survey mainly understands the cost considered by the enterprise. The surveyors know what aspects of costs are mainly considered by enterprises in cost calculation through inquiry, and record them. When the interviewees could not answer, the researchers would remind them based on the results of the literature analysis, such as whether the cost of carbon emissions was considered. Through sorting, it is found that the costs considered by the eight companies mainly involve fixed costs, transportation costs, penalty costs, refrigeration costs, cargo loss costs and carbon emission costs, as shown in Table 2. Three companies accounted for all six costs at the same time, while the others accounted for only some of them.

Table 2. The main costs considered by the surveyed companies.

Company number	Fixed cost	Transportation cost	Penalty cost	Cargo loss  cost	Refrigeration cost	Carbon emission  cost
1	√	√	√	√	√	√
2	√	√			√
3	√	√	√	√	√	√
4	√	√	√	√
5	√	√
6	√	√	√	√	√	√
7	√	√	√
8	√	√			√

Note: A "√" indicates that the company has taken this cost into account.

 

7) Reviewer Comment: What is the difference between your proposed method with other existing methods? You need to highlight the differences and novelty of the paper in the different parts of the paper. For example, in Section 3.3.

Reply: Thank you very much for your suggestion. As you suggest, we have highlighted the differences and novelty of the paper in different sections of the article. The main difference between this paper and the existing studies is the research content, which comprehensively considers the time window, carbon emission and mixed vehicle types to establish the cold chain distribution optimization model of fresh agricultural products. The purpose of establishing the model is to achieve both economic and environmental benefits and promote the sustainable development of cold chain logistics of fresh agricultural products. First of all, after literature comparison in the literature review section, we specifically explained the differences of the articles. Secondly, in the added "discussion" section we emphasized the characteristics of the article again. In addition, we have explained the differences and significance of the article many times in the third chapter. For example, the following content is added to the text.

As the demand for cold chain distribution of fresh agricultural products is strong, and carbon emission and distribution of various vehicle types are realistic problems that have to be considered, this paper intends to comprehensively consider the four factors mentioned above, and explore the optimization of cold chain distribution path of mixed vehicle types of fresh agricultural products considering carbon emission, in order to provide decision-making reference for the sustainable development of cold chain of agricultural products. The main features of this study are as follows: (1) Considering the time window constraint in the optimization of the distribution path. Maximize customer requirements for delivery time and improve customer satisfaction. (2) Consider the carbon emissions in the cold chain distribution of fresh agricultural products. Pursue economic benefits while improving environmental benefits. (3) Consider the impact of the distribution of multiple types of vehicles. Rationally allocate vehicle resources according to realistic conditions.

According to literature analysis and investigation, in order to reduce the carbon emissions in the cold chain distribution of fresh agricultural products, the cost of carbon emissions can be calculated and controlled. At the same time, in order to achieve the overall optimization, the fixed cost, transportation cost, penalty cost, cargo loss cost, refrigeration cost and carbon emission cost, which account for a relatively large proportion, should be considered comprehensively, and the total cost should be minimized. In terms of constraints, in addition to considering the time required by customers, how to rationally allocate a variety of vehicle resources such as gasoline refrigerated vehicles, pure electric refrigerated vehicles, and gas-electric dual-use refrigerated vehicles is a practical problem worth considering. In order to achieve both economic and environmental benefits and promote the sustainable development of cold chain logistics of fresh agricultural products, it is particularly necessary to consider the time window and mixed vehicle types when planning the distribution route, and to minimize the total cost including carbon emission cost as the optimization goal.

8) Reviewer Comment: There is no discussion in the article. I suggest adding a Discussion section to compare the results with the available literature.

Reply: Thank you very much for your suggestion. According to your suggestion, we have added a "Discussion" section before the "Conclusions", as follows:

5. Discussion

Reasonable planning of cold chain logistics distribution route is an important measure to save logistics resources, reduce the impact on the environment, and promote the sustainable development of agricultural cold chain logistics. On the basis of field investigation, this paper establishes a new optimization model of cold chain distribution route for fresh agricultural products, and carries out an example analysis. The results show that:

(1) It is necessary and feasible for cold chain distribution route planning of fresh agricultural products to comprehensively consider factors such as carbon emissions and mixed vehicle types. In view of the high timeliness requirements and high energy consumption of cold chain distribution of fresh agricultural products, the planning of distribution routes should not only consider the constraints of the time window, but also consider how to rationally use vehicle resources, give play to the advantages of different types of vehicles, in order to reduce distribution costs and reduce carbon emissions. Compared with the decision-making model that considers a single or a few factors, the model that considers the time window, carbon emission and hybrid vehicle can better balance the economic and environmental benefits, and has better application value in the current realistic conditions.

(2) The optimal overall cost should be pursued in the cold chain distribution route planning of fresh agricultural products. Cold chain distribution process will produce a variety of costs, if only pay attention to one or two of the costs, may lead to the increase of other costs, affecting the overall operation effect. Therefore, when planning the distribution route, we should fully understand the possible costs, and pursue the minimum comprehensive cost. From the characteristics of cold chain distribution of fresh agricultural products, fixed cost, transportation cost, penalty cost, cargo loss cost, refrigeration cost and carbon emissions cost are components that can not be ignored, and should be comprehensively considered in decision-making.

(3) Genetic algorithm is an effective method to solve the cold chain distribution route optimization model of fresh agricultural products. There are many methods to solve mathematical models, and each has its own advantages. In this paper, genetic algorithm is chosen to solve the problem. From the algorithm design and practical application, the algorithm can explain the model decision thinking well and help find the optimal solution quickly, so it is an effective solution method. Of course, if the model is further optimized, genetic algorithms mixed with other methods can be tried to improve the ability to solve the problem.

Special thanks again for your suggestions.

Kind regards,

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The paper/manuscript was completed correctly.

Author Response

Dear reviewer,

    Thank you very much for your comments. We really appreciate your recognition and support.

    Kind regards,

Reviewer 3 Report

Comments and Suggestions for Authors

The authors have responded to all the comments of the first round of review. I am satisfied with the responses. I have two comments:

1. I would suggest adding more keywords.

2. In the Discussion section, the authors should connect the results to other studies. Please add references.

Author Response

Dear reviewer,

Thank you for your comments on our paper again. We have made further modifications according to your suggestions, and the revised portions of the paper are marked in purple. The details are as follows.  

1) Reviewer Comment: I would suggest adding more keywords.

Reply: Thank you very much for your suggestion. As you suggest, we have added three keywords according to the content of the article, which are as follows:

Keywords: distribution; vehicle; carbon; route; cost; optimization; algorithm

 

2) Reviewer Comment: In the Discussion section, the authors should connect the results to other studies. Please add references.

Reply: Thank you very much for your suggestion. According to your suggestion, we have added some expressions in the Discussion section to show how the findings relate to other studies. Since we have already listed studies closely related to or similar to this study in the Literature Review section, we did not add new literatures, but compared the results with those previously listed. The modification is as follows:

5. Discussion

Reasonable planning of cold chain logistics distribution route is an important measure to save logistics resources, reduce the impact on the environment, and promote the sustainable development of agricultural cold chain logistics. On the basis of field investigation, this paper establishes a new optimization model of cold chain distribution route for fresh agricultural products, and carries out an example analysis. The results show that:

(1) It is necessary and feasible for cold chain distribution route planning of fresh agricultural products to comprehensively consider factors such as carbon emissions and mixed vehicle types. In view of the high timeliness requirements and high energy consumption of cold chain distribution of fresh agricultural products, the planning of distribution routes should not only consider the constraints of the time window, but also consider how to rationally use vehicle resources, give play to the advantages of different types of vehicles, in order to reduce distribution costs and reduce carbon emissions. This paper is a helpful supplement to the existing researches. In the study of cold chain distribution route of fresh agricultural products, Ho et al. [8], Ding et al. [9],Wu et al. [10], Wang et al. [11] took the time window constraint into consideration; Fu et al. [24], Yao et al. [25], Feng et al. [26], Pérez-Lechuga et al. [27] Considering the time window and carbon emissions; Leung et al. [33], Kwon et al. [34] and Chen et al. [35] consider the time window and mixed vehicle types. In this paper, the three factors mentioned above are taken into account to establish a decision-making model, which can better balance economic benefits and environmental benefits, and has good application value in the current practical conditions.

(2) The optimal overall cost should be pursued in the cold chain distribution route planning of fresh agricultural products. Cold chain distribution process will produce a variety of costs, if only pay attention to a few costs, may lead to the increase of other costs, affecting the overall operation effect. Therefore, when planning the distribution route, we should fully understand the possible costs, and pursue the minimum comprehensive cost. Previous studies have considered the cost of cold chain distribution of fresh agricultural products from different perspectives. For example, Wang et al. [11] took into account the cost of freshness loss, cold chain refrigeration cost and delay penalty cost; Jiang et al. [22] took into account the cost of transportation, refrigeration cost and carbon emission cost; Ma et al. [23] considered fixed transportation cost, variable transportation cost, time penalty cost and carbon emission cost. This paper comprehensively considers six major costs in the cold chain distribution of fresh agricultural products, including fixed cost, transportation cost, penalty cost, cargo loss cost, refrigeration cost and carbon emission cost, which is conducive to improving the effectiveness of decision-making.

(3) Genetic algorithm is an effective method to solve the cold chain distribution route optimization model of fresh agricultural products. There are many methods to solve mathematical models, and each has its own advantages. Similar to the studies of Liu & Li [7], Jiang et al. [22], Chen et al. [35], this paper selects genetic algorithm to solve the problem based on the characteristics of the model. From the algorithm design and practical application, the algorithm can explain the model decision thinking well and help find the optimal solution quickly, so it is an effective solution method. Of course, if the model is further optimized, genetic algorithms mixed with other methods can be tried to improve the ability to solve the problem.

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