Optimal Control Policy of Unreliable Production Systems Generating Greenhouse Gas Emission
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe English quality of the manuscript is very poor. The structure of the manuscript is relatively complete, and the analysis process and mathematical models are complete. The shortcomings are that further innovative analysis and interpretation of the conclusions drawn from the analysis are needed, and better optimization and analysis are needed. The research results of the manuscript seem to have less significant contributions to this field than the author explained. The author needs to continue to strengthen the conclusions and scientificity of the research in the analysis section, and point out the shortcomings of the research and the directions for further research.
Comments for author File: 
Comments.pdf
The English quality of the manuscript is poor.
Author Response
We would like to thank the reviewer for his valuable suggestions and comments on our document. We revised the manuscript accordingly, with changes highlighted in red. The attached document provides a detailed summary of the authors' responses to the review comments.
We made revisions relating to the questions raised by the evaluator. The answers to these questions are detailed below:
Pages 1; Section-Keywords: The author modifies words that overlap with the title.
We have revised the keywords section by replacing Greenhouse gas emission with environmental constraints to avoid any overlap with the title of the article.
Pages 2; Section-Abstract: The author's modifications are divided into: raising questions. The methods and theoretical models used in the study; Has the scientific and practicality of the optimized model been improved?
We have revised the structure of the abstract of the article according to the logic which consists of presenting the problem studied, the research questions, the methodology, the theoretical models proposed, the analysis of the results, the scientific contributions and the potential industrial application of the results obtained. The optimal policies resulting from this research have shown their superiority compared to work based on non-optimal policies.
Pages 3. Section-Literature review: The author has read some published research articles, but the shortcomings and supplementary content in this research direction have not been thoroughly analyzed. Please make revisions and additions in the section on page 5.
We have revised the literature review section with modifications and additions at the end of the section to highlight gaps and analyze in depth the additional content of this research direction (see page 5 of the revised manuscript).
Pages 4. Section-3. Problem formulation: Please change the title to Methods.
The title of section 3 has been changed from Problem formulation to Methods.
Pages 5. Section-Figure 2. Optimal control policy structure: Please label the R2 value obtained after optimization analysis to determine whether your optimized numerical model has been improved.
The theorem presented in Appendix A following the numerical version of the HJB equations (see page 21) shows that when the discretization step tends towards zero, then the numerical solution of the optimization problem converges to the analytical solution. For relatively small discretization steps in this work, we can claim that the policy structure shown in Fig. 2 is that of the optimal policy (see page 8).
Pages 6. Section-5.4. Effect of emission index: Please use analysis data to illustrate the meaning contained in this sentence: In addition, the sensitivity analysis results make sense, which validate the proposed resolution approach robustness.
This section shows that, in the absence of real data on the emissions index, a sensitivity analysis covering a range of possible values for this index has enabled us to establish the generality of the approach and the robustness of the proposed approach (see text added on page 11).
Pages 7. Section-7. Discussion: Please conduct a more in-depth analysis of the conclusions obtained and explain the reasons for the data differences in scientific language.
We have reorganized the conclusion with an in-depth analysis of the conclusions obtained and explained the scientific contributions by highlighting the dependence of the optimal policy on inventories and emissions, the robustness through sensitivity analysis, the comparative study to show the optimality of the policy obtained, Feasibility and Managerial Implementation.
Pages 8. Section - 8. Conclusion: Please provide additional explanations on the shortcomings of this study and the areas that need to be strengthened in the future.
At the end of the conclusion section, we've added text on the possibility of incorporating advanced artificial intelligence (AI) and machine learning (ML) techniques to further optimize production control policies (see page 18).
Pages 9. Section-Paper: Please check the English quality and accuracy of the entire manuscript. The English must be carefully proofread and checked.
The English quality of the manuscript has been considerably improved by a thorough revision of the entire article.
The abstract is revised as suggested by the reviewer. The statement in the original manuscript is replaced by the revised statement proposed by the reviewer.
Author Response File: Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for Authors
This manuscript “Optimal control policy of unreliable production systems generating greenhouse gas emission” has studied the control policy of unreliable production systems generating greenhouse gas emission. The paper is interesting. However, the manuscript has some defect. Thus, I suggest that the paper be major revision.
Q1: The “ 8 Conclusion ” should be revised as “ 8 Conclusions ”.
Q2: The writing and grammar should be improved, especially the current version of the manuscript. For example: “The developed model in [25] addressed the balance between carbon emissions and production costs, noting that green production results in fewer…”.
Q3: In the paper, Authors should try to avoid using the first person as much as possible, such as me, our, we, us. For example, Line 443. The author should be improved. For example: “From table 2, we notice that when the shortage unit cost increases, the corresponding critical production thresholds increase (the system stores more) to…”
Q4: The conclusion and Abstract are not well organized and should be improved.
Q5: Some references should be added in the section 3.2, such as equations.
Q6: The innovation or contributions of this paper should be further summarized. In the section Results and discussion, the author has not explained the reason and why the interesting phenomenon occurs and what is the mechanism.
Q7: The authors must highlight their own findings from literature review.
Comments on the Quality of English LanguagePlease see the Comments and Suggestions for Authors.
Author Response
This manuscript “Optimal control policy of unreliable production systems generating greenhouse gas emission” has studied the control policy of unreliable production systems generating greenhouse gas emission. The paper is interesting. However, the manuscript has some defect. Thus, I suggest that the paper be major revision.
Q1: The “ 8 Conclusion ” should be revised as “ 8 Conclusions ”.
The title of section 8 has been changed from Conclusion to Conclusions.
Q2: The writing and grammar should be improved, especially the current version of the manuscript. For example: “The developed model in [25] addressed the balance between carbon emissions and production costs, noting that green production results in fewer…”.
The English quality of the manuscript has been considerably improved by a thorough revision of the entire article.
Q3: In the paper, Authors should try to avoid using the first person as much as possible, such as me, our, we, us. For example, Line 443. The author should be improved. For example: “From table 2, we notice that when the shortage unit cost increases, the corresponding critical production thresholds increase (the system stores more) to…”
Sentences in which We, Our and Us appear have been reworded to avoid the use of the first person throughout the article.
Q4: The conclusion and Abstract are not well organized and should be improved.
We have reorganized the conclusion to include an in-depth analysis of the conclusions obtained and explained the scientific contributions by highlighting the dependence of the optimal policy on inventories and emissions, the robustness demonstrated through sensitivity analysis, the comparative study showing the optimality of the policy obtained, and the feasibility and managerial implementation.
We have also revised the structure of the abstract to follow the logic of presenting the problem studied, the research questions, the methodology, the theoretical models proposed, the analysis of the results, the scientific contributions and the potential industrial application of the results obtained. The optimal policies resulting from this research have shown their superiority compared to previous work based on non-optimal policies.
Q5: Some references should be added in the section 3.2, such as equations.
The equations in section 3.2 are numbered, and reference [26] is used to justify equation (2) on emission dynamics.
Q6: The innovation or contributions of this paper should be further summarized. In the section Results and discussion, the author has not explained the reason and why the interesting phenomenon occurs and what is the mechanism.
We have revised the literature review section with modifications and additions at the end of the section to highlight gaps and contributions in depth the additional content of this research direction (see page 5 of the revised manuscript). We have also reorganized the conclusion with an in-depth analysis of the conclusions obtained and explained the scientific contributions by highlighting the dependence of the optimal policy on inventories and emissions, the robustness through sensitivity analysis, the comparative study to show the optimality of the policy obtained, Feasibility and Managerial Implementation.
Q7: The authors must highlight their own findings from literature review.
From the literature review, it is noted that, none have developed an optimal production policy for dynamic systems encountering stochastic failures and repairs, as highlighted in Table 1 (last line). This table outlines the research gaps and contributions of the work. Previous research did not create new optimal control policies but instead adapted existing policies from the literature or relied on common-sense approaches. The study addresses this gap by applying stochastic optimal control theory grounded in the dynamic programming framework to develop a new optimal control policy.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsI suggest adding realistic data to the introduction to better demonstrate the need to reduce greenhouse gas emissions.
The author has made a very detailed elaboration in the literature review, can it be concise and logical, grasp the main line and highlight the key points of the article?
Sensitivity analysis and comparative studies are better if they can be compared with the results of other people's research and the conclusions to be demonstrated.
I suggest that the authors state in the conclusion the limitations of this paper, the challenges, and how they intend to further advance the research.
Comments on the Quality of English LanguageIt is good.
Author Response
I suggest adding realistic data to the introduction to better demonstrate the need to reduce greenhouse gas emissions.
We understand the importance of demonstrating the need to reduce greenhouse gas emissions with realistic, concrete data. However, we currently have no specific practical data to support this study. In the absence of real data on the emissions index, a sensitivity analysis covering this range of possible values for this index could establish the generality of the approach and the robustness of the proposed approach (see page 11).
The author has made a very detailed elaboration in the literature review, can it be concise and logical, grasp the main line and highlight the key points of the article?
We have given a detailed development in the literature review. The last line of Table 1 specifies the main objective of the article, and the contributions are presented at the end of the literature review section (see page 5).
Sensitivity analysis and comparative studies are better if they can be compared with the results of other people's research and the conclusions to be demonstrated.
We have reorganized the conclusion with an in-depth analysis of the conclusions obtained and explained the scientific contributions by highlighting the dependence of the optimal policy on inventories and emissions, the robustness through sensitivity analysis, the comparative study to show the optimality of the policy obtained, Feasibility and Managerial Implementation.
I suggest that the authors state in the conclusion the limitations of this paper, the challenges, and how they intend to further advance the research.
At the end of the conclusion section, we've added text on the possibility of incorporating advanced artificial intelligence (AI) and machine learning (ML) techniques to further optimize production control policies (see page 18).
Author Response File: Author Response.pdf
Reviewer 4 Report
Comments and Suggestions for AuthorsDear authors, I can see that the article “Optimal control policy of unreliable production systems generating greenhouse gas emission” has a great potential.
Unfortunately, there are issues to present research results with the requirements of the journal.
Please, see examples of the Sustainablity journal articles to improve your research.
Research Manuscript Sections
- Introduction: The introduction should briefly place the study in a broad context and highlight why it is important. It should define the purpose of the work and its significance, including specific hypotheses being tested. The current state of the research field should be reviewed carefully and key publications cited. Please highlight controversial and diverging hypotheses when necessary. Finally, briefly mention the main aim of the work and highlight the main conclusions. Keep the introduction comprehensible to scientists working outside the topic of the paper.
(Your literature review section is very long and doesn’t fulfill the requirements)
- Materials and Methods: They should be described with sufficient detail to allow others to replicate and build on published results. New methods and protocols should be described in detail while well-established methods can be briefly described and appropriately cited. Give the name and version of any software used and make clear whether computer code used is available. Include any pre-registration codes.
(This section is missing. Not structured. You have all the necessary materials, but you need to structure them)
- Results: Provide a concise and precise description of the experimental results, their interpretation as well as the experimental conclusions that can be drawn.
(Presented. Needs to be structured)
- Discussion: Authors should discuss the results and how they can be interpreted in perspective of previous studies and of the working hypotheses. The findings and their implications should be discussed in the broadest context possible and limitations of the work highlighted. Future research directions may also be mentioned. This section may be combined with Results.
(Presented. Needs to be structured)
Conclusions: This section is not mandatory but can be added to the manuscript if the discussion is unusually long or complex.
Author Response
We would like to thank the reviewer for his valuable suggestions and comments on our document. We revised the manuscript accordingly, with changes highlighted in red. The attached document provides a detailed summary of the authors' responses to the review comments.
Thank you for your comments on our manuscript entitled “Optimal Control Policy of Unreliable Production Systems Generating Greenhouse Gas Emissions”. We appreciate your recognition of the potential of our work.
We acknowledge the problems highlighted regarding the presentation of our research results in accordance with journal requirements. To address this, we have examined examples of articles published in the journal Sustainability to gain a better understanding of the expected formatting, structure, and detail. We have proofread our article, made corrections, and rewritten and reorganized several sections.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Comments and Suggestions for AuthorsThe authors have carried out a thorough and careful revision and the revised manuscript improved a lot in terms of technical quality and language. Therefore, I would recommend it for publication in the Journal.
Comments on the Quality of English LanguagePlease see the Comments and Suggestions for Authors.
Reviewer 4 Report
Comments and Suggestions for AuthorsAccept in present form
