Task Scheduling Problem of Double-Deep Multi-Tier Shuttle Warehousing Systems

Round 1

Reviewer 1 Report

Manuscripts main concerns are related with the following:

• English language should be revised, as there are many gramatical errors.
• References where more than one author are involved, should be mentioned as FirstAuthor et al., not only the first author surname. Also, in line 281, a different type of reference is used, please unify template.
• Revise and explain equations 19, 20 and 22, where an equal to 0 expressions are shown.
• Problem to solve is a 3 objective optimization problem; however, the NSGA-II algorithm is not a state-of-the-art algorithm when the number of objectives functions is equal or greater than 3; at least other algorithms such as SMS-EMOA or MOEA/D more appropriate for 3 or more objectives should be applied and compared with the results.
• The transformation of optimization problem using inverse function is also questionable, as there could have been used the dual principle, which only needs a change of sign and does not modify the problem landscape. Is there any reason to have proceeded in such way?
• Instead of mentioning Pareto solutions, throughout the paper, the term "non-dominated solutions" is more appropriate, as Pareto set (or Pareto front) should only be refered when mentioning the absolute global optima.
• Only one set of parameters have been proposed (lines 390-393), but it is recommended to test a set of different combination and compare them with statistical significance tests in order to attain the best performance of the optimizer.
• A detail explanation of the chromosome should be included (structure, number of variables, codification, etc.)
• Additionally to table 4, also at least some non-dominated solutions should be detailed in terms of values of chromosome variables.
• The convergence of the execution has been tested for stagnation? Number of fitness evaluations run have been enough for achieving a converged non-dominated set? The hypervolume indicator convergence should be plotted for that purpose in order to check a stabilized slope.

Author Response

Thank you for your excellent and detailed comments. Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our research. We have studied comments carefully and have made correction which we hope meet with approval. All the revisions are marked in red font in the revised manuscript. As a result, the manuscript has been greatly improved.

We have responded to your comments point by point, and you can check these responses in the Cover Letter. Once again, thank you very much for your comments and suggestions.

Author Response File: Author Response.docx

Reviewer 2 Report

The paper concentrates on Double-deep multi-tier shuttle warehousing system DMSWS), a new intelligent warehousing system.

Strengths of the paper:

1. Interesting study of the results, considering emissions and waiting or free time.
2. Generally good writing skills
3. Good structure of the paper.

 

However, before publication the paper needs following improvements:

Regarding the introduction:

• Include references in the introduction when making statements such as “In most studies, double-deep SR increases storage positions by 40%-50%, compared with single-deep SR”
• Although reference is made to the gap to be covered by this study, it should be commented on more explicitly.
• In the research questions, the authors mix these questions or approaches with the results. Indicate both separately, including a paragraph with the main results achieved.

Regarding the theoretical review: Include the relationship between sustainability and warehouse management system. Examples of articles that may be useful for the authors;

• Mohammadehsan Torabizadeh, Noordin Mohd Yusof, Azanizawati Ma’aram, Awaluddin Mohamed Shaharoun, Identifying sustainable warehouse management system indicators and proposing new weighting method, Journal of Cleaner Production, Volume 248, 2020, 119190.
• Seval Ene, İlker Küçükoğlu, Aslı Aksoy, Nursel Öztürk. A genetic algorithm for minimizing energy consumption in warehouses, Energy, Volume 114, 2016, Pages 973-980.
• Hao, J.; Shi, H.; Shi, V.; Yang, C. Adoption of Automatic Warehousing Systems in Logistics Firms: A Technology–Organization–Environment Framework. Sustainability 2020, 12, 5185.
• Guerrazzi, E.; Mininno, V.; Aloini, D.; Dulmin, R.; Scarpelli, C.; Sabatini, M. Energy Evaluation of Deep-Lane Autonomous Vehicle Storage and Retrieval System. Sustainability 2019, 11, 3817.

Regarding the conclusions. To expand them substantially, including the practical contribution of the results obtained. Similarly, the limitations and the extension of future recommendation.

I hope that my comments are helpful to you.

Author Response

Thank you for your excellent and detailed comments. Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our research. We have studied comments carefully and have made correction which we hope meet with approval. In addition, we have the paper spellchecked before considering the new submission. The grammatical and spellings errors have been corrected. All the revisions are marked in red font in the revised manuscript. As a result, the manuscript has been greatly improved.

We have responded to your comments point by point, and you can check these responses in the Cover Letter. Once again, thank you very much for your comments and suggestions.

Author Response File: Author Response.docx

Reviewer 3 Report

This paper studied carbon emission and cycle times of warehouse equipment in their article, “Task scheduling problem of double-deep multi-tier shuttle warehousing”. The focus was to analyze a comprehensive optimization model of cycle time and carbon emissions to reduce cycle times and carbon emissions of equipment. Though there has been a rise of researches on carbon emissions of warehouse equipment, the researchers indicated that much has not been done to reduce carbon emissions in the “task scheduling problem”. The researchers analyzed the existing literature on warehouse carbon emissions and cycle times to understand the effect of operations arrangement. Also, cycle times were presented in a “flow stop scheduling model”. They implemented the model in a case study. The following are some suggestions for the authors to consider.

1. Figure 3 shows a linear process of flow chart for retrieval task. Is it possible to make it multi-tasking?
2. The paper claims that "The results show that the integrated optimization model can reduce the carbon emission and improve system efficiency. In addition, it also can reduce operation costs and improve the utilization of the equipment." It needs to elaborate on how carbon emission can be used to indicate system efficiency.
3. How much cost is reduced and equipment utilization is improved? The authors should explain the answers in the abstract, introduction, and analysis.
4. How would you plan to generalize the results? What are the practical implications?

 

Author Response

Thank you for your excellent and detailed comments. Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our research. We have studied comments carefully and have made correction which we hope meet with approval. In addition, we have the paper spellchecked before considering the new submission. The grammatical and spellings errors have been corrected. All the revisions are marked in red font in the revised manuscript. As a result, the manuscript has been greatly improved.

We have responded to your comments point by point, and you can check these responses in the Cover Letter. Once again, thank you very much for your comments and suggestions.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

This reviewer recognises the effort of the authors to consider and improve the manuscript according to the amendments in the first review.
However there are still some concerns that have not been fully attended, that have to be improved with the minimum content as detailed below:

In relation with:

"Point 9: Additionally to table 4, also at least some non-dominated solutions should be detailed in terms of values of chromosome variables.":
The three solutions with best values for each objective have been chosen and commented in the manuscript. However, detailed solutions (that is, e.g., values of the chromosome variables associated to each solution, not only the value of the 3 objective functions) as requested, are not provided.
If the amount of data is high, include them in an Anex. Also some additional solution that belongs to the inner part of the non-dominated front should be included (not only the 3 extreme solutions as suggested) in the previous data.

In relation to point 10, hypervolume convergence curves as suggested have been not provided, but only best values of 2 of the 3 objective functions. Those convergence curves that are shown in the reviewer's answer (point 10) are not included in the article content. They should at least be included also in the manuscript.

Author Response

Thank you for your excellent and detailed comments. Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our research. We have studied comments carefully and have made correction which we hope meet with approval. All the revisions are marked in red font in the revised manuscript. As a result, the manuscript has been greatly improved.

We tried our best to improve the manuscript and made some changes in the manuscript. These changes will not influence the content and framework of the paper. we have responded to your comments point by point，and you can check therse responses in the Cover Letter. Once again, thank you very much for your comments and suggestions.

Author Response File: Author Response.pdf

Round 3

Reviewer 1 Report

Authors have taken into account the suggested amendments.

Only some minor amendments are required:

As all the non-dominated solutions chromosome details are exposed in table 7, now table 6 is not neccesary as it contains redundant information; therefore, please delete table 6.

In figure 11 an hypervolume convergence curve has been provided as suggested. Nevertheless, the single reference point values used for hypervolume indicator calculation should be detailed (either in the text or in the figure label).

Author Response

Thank you for your excellent and detailed comments. Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our research. We have studied comments carefully and have made correction which we hope meet with approval. All the revisions are marked in red font in the revised manuscript. As a result, the manuscript has been greatly improved.

We tried our best to improve the manuscript and made some changes in the manuscript. These changes will not influence the content and framework of the paper. we have responded to your comments point by point，and you can check therse responses in the Cover Letter. Once again, thank you very much for your comments and suggestions.

Author Response File: Author Response.pdf