Development of a New Green Indicator and Its Implementation in a Cyber–Physical System for a Green Supply Chain

Round 1

Reviewer 1 Report

This study proposed new key performance indicators and a CPS-based framework for improving an illustrative case from the manufacturing sector. I provided a list of my concerns and suggestions for improvement.

Abstract.

You need to conclude your abstract by highlighting the major findings, i.e. the extent of the improvement and the dimensions of improvement.

Introduction.

This section should be completely restructured. It is not recommended to use sub-sections for the introduction part of an academic research paper. Instead, you may begin your introduction by a background paragraph. You may continue by stating a practical problem. The third paragraph can be an overall view of the academic approaches developed to address this problem. The fourth paragraph should review the most relevant research works with a critical lens in an effort to identify the research gap/question. Next, you need to clearly state the contribution(s) of your work in addressing the stated research gap. Finally, you may finish the section by providing the outline of your research article.

The introduction section is of high importance because it can encourage the reader to go to the rest of your research paper. There must be a logical order between the paragraphs, and the reader should clearly understand the objective of your research.

You can structure your introduction in various ways. Following is my suggestion. Given that your work is at the intersection of GSCM, CE, and Industry 4.0, you may begin with a background on GSCM and CE; continue by introducing Industry 4.0. as a solution; reviewing the most relevant works where Industry 4.0 applications are considered for GSCM/CE, and state a clear research gap based upon the critical review.

Literature review.

I would like to see much of the contents of the current Introduction moved to a new section named Literature Review. Please note that the review I mentioned earlier for the introduction section is only about THE MOST RELEVANT WORKS. They may be repeated in the second section with the objective of re-stating the research gap as a result of the literature review you conducted.

Materials and methods.

Your research title, keywords, abstract and the introduction contains Green Supply Chain as its core, yet you have dismissed it in your explanations in section 2.1. You may provide some relevant GSCM references, for example: "A Practical Review of Green Supply Chain Management: Disciplines and Best Practices". There are many other relevant review papers that can be cited in this section. 

In section 2.2. the term "Energy consumption losses" should be changed to "Energy losses".

Given that CPS has been widely used to enhance the manufacturing process intelligence and establish effective interaction between the virtual and physical environments, you need to provide some examples of its successful applications and cite the relevant papers.

The formulations in section 2 should be typed using professional software; my suggestion is MathType.

You need to define a logical connection between sections 2.2 and 2.3, that is, you need to explain in detail how the outcomes coming from CPS will be used to generate the necessary input for calculating the proposed KPIs. I would suggest a drawing or flow-chart. Besides, the current explanations are not enough. What you proposed must be replicable by your potential readers while your current manuscript is hardly replicable.

Section 2.5 should be moved to results and discussions.

The illustrative case example you provided is not explained sufficiently.

There are referencing errors in lines 252, 287-288.

The most important practical implication of your work is "the use of the green KPI highlights areas of improvement to the company from a sustainable point of view". It is great, but other similar studies are not cited in your manuscript. You cited Wudhikarn et al. (2010), but this is not the only example, I believe.

The definition of "overall equipment effectiveness" is not good enough. It is too broad and unclear. Why is this preferred to OECL? Why haven't you compared OEE and OECL in the numerical analysis? You need to somehow prove that your measures are better than the existing one(s).

You need to elaborate on the practical implications. What you provided in Lines 320-326, is not sufficient. Besides, it is not directly supported by the numerical results in your study.

Conclusions.

You need to include the major findings in the conclusion part; please make sure that the stated findings are well supported by numerical results. Besides, there are limitations to your study. You need to list them here. This will also help to provide insights for future work. 

Overall, your manuscript in its current form is more like a consulting report. You need to improve your presentation and follow the common academic conventions for identifying the gap that supports the purpose and value of your study. In addition to improving these aspects, I would like to see some improvement in the numerical analysis, i.e. including OECL in your benchmark.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

First of all, thank you for your contribution.

The submitted manuscript presents an overview of various lean-oriented methods for developing indicators and key figures. In this context, a new indicator, the ECL (energy consumption losses), is developed. This indicator is closely related to production losses and is comparable to OEE in the sense of a "green" indicator. Unfortunately, some ecological aspects are missing in the consideration and the application to the use case has to be reconsidered. Furthermore, the idea of the green supply chain is not fully applied, and the CPS is not completely developed.

General comments:

• Please have a further look at the overall style and format of the paper
• In almost every chapter the references are lost and displayed as "error"
• Please have a look at the overall spelling
• Please have a look at the format of the references

Specific comments:

1. Introduction

• Consider renaming chapter 1.1 because it is right now more about CPS than industry 4.0
• Please explain further how the information chain from 1.2, 1.3 to 1.4 is given. Why are Lean aspects relevant for a Green Supply Chain? And also, why you are referring to them here because they are not a factor of Industry4.0 (which is explained before)
• You are only referring to one aspect of the lean management here. The six big losses are just one point in the waste reduction concept of the lean aspects. For example, the concept of Muda, Mura, Mudi could be used here, if you are using waste reduction methods. It is clear why you are using the 6 big losses but there should be minimum a comparison to other methods.
• In 1.5 you are referring to this: "The challenge is no longer for enterprises to be competing with each other, but rather for them to achieve the leanest SC and to keep up with changes occurring in the industrial world." - This has to be referenced because I would highly doubt that the industry is only focusing on the leanest SC and not on competition. Maybe rephrase this sentence.

2. Materials and Methods

• Figure 3 should be revised. The doubling of a performance indicator is not the right way to visualize the impact of the OEE on these factors.
• The calculation of the KPI is very blurred and should be optimized.
• In 2.3 there should be a description and discussion of why this system is used (especially the language) and how other systems could look like, even with the outlook to other industry companies.
• Figure 4 should be revised. The CPS would be the whole underline and the IoT refers to the sensor and data part of the picture. As you already described a CPS consists of a physical and cyber component. Therefore, you cannot leave out the cloud and visualization in the CPS.
• Please consider if the ECL can be an extension of the OEE as has been done several times before. Since the values are based on each other, an adaptation of the indicator would be helpful. This should be made clear in the text.

3. Results and discussions

• The results in Table 1 could be clearer and directly related to each other
• Figure 6 should be revised optically
• It is already clear (chapter 1 and 2) that there is no indication of the sustainability of the OEE, this should not be stated out here
• It should be also considered to rearrange the ECL from "losses" to "savings", therefore the comparison of the OEE and the ECL would make more sense
• There is much more potential in the results than to compare them to the OEE and with regard to the machine with the highest / lowest ratio.
• It is already mentioned and clear that there is no direct relation between the ECL and the OEE. A transfer concept for a machine park and an extended use-case would be valuable.
• There is no relation of the results to the whole supply chain which is mentioned in the paper title
• The work should be transferred to a wider field of machines or the supply chain needs to be included more

4. Conclusions

• Here it is stated "predictive maintenance was also considered" (and the other considerations you mention here in advance) -  why is this not shown in the results? This would produce a higher outcome of the paper.

Please consider rephrasing this: "In addition, this study highlights the important role that Industry 4.0 technologies can play in assisting the attainment of a GSC.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

In regard to your response below:

"We have worked with OECL and we have done some modifications to implement it in our CPS. However, we consider that the OECL calculation is out of the scope of this article, given that, it is an economical KPI, and it is not directly related with Green Supply Chain."

You need to provide this justification in the manuscript; for example, you may argue that myopic financial thinking is not sustainable and the measures you provided help address this issue. 

There are many minor issues that need to be addressed before proceeding with this manuscript. Some of them are listed below.

"However, the best KPI cannot be determined" is very subjective. Please provide some evidence from the existing literature.

"are few developed" in Line 53 does not convey any meaning.

"A great example of is Apple" in Line 204 should be corrected.

"As can be seeing in" in Line 320 should be corrected.

"energy consumption waste" is a wrong phrase; "energy waste" sounds better.

Careful proofreading is a must to correct unwanted mistakes and improve readability. Finally, you need to add a paragraph at the end of the introduction section to provide an outline to the rest of your manuscript.

Author Response

Thank you very much for your review. Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Thanks for the updated manuscript. I addressed a few points again to give you further feedback. If some points are not answered, they are ok in my view.

The submitted manuscript presents an overview of various lean-oriented methods for developing indicators and key figures. In this context, a new indicator, the ECL (energy consumption losses), is developed. This indicator is closely related to production losses and is comparable to OEE in the sense of a "green" indicator. Unfortunately, some ecological aspects are missing in the consideration and the application to the use case has to be reconsidered. Furthermore, the idea of the green supply chain is not fully applied, and the CPS is not completely developed.

General comments:

• Please have a further look at the overall style and format of the paper. The first section has been modified and divided in Introduction and Literature Review, where more literature has been added. --> Please have again a look at the formatting: 2.1 is i.e. on the same line as 2.

• In almost every chapter the references are lost and displayed as "error". This error has been solved. --> For me this has not been solved. For example, the error is displayed in line 311, 410, 413, and so on

Specific comments:

1. Introduction

• You are only referring to one aspect of the lean management here. The six big losses are just one point in the waste reduction concept of the lean aspects. For example, the concept of Muda, Mura, Mudi could be used here, if you are using waste reduction methods. It is clear why you are using the 6 big losses but there should be minimum a comparison to other methods. Muda, Mura and Mudi concepts has been included in lines 158 - 164. --> Nice addition, please check the section again for spelling and grammar. Also, the new paragraph is not linked directly to the next section which was included before.

Also check the paper for extra spaces and free sections.

3. Results and discussions 3

• Figure 6 should be revised optically. We don’t know what’s wrong with this figure. --> This comment was related to the design of the Figure. It should be adapted so that it fits to the overall paper design. In general, the design of the Figures changes a lot (used colours, picture language, etc.). It should adjusted, so that the visualization appears to be from a single source.

In general, the adjustments and optimizations of the manuscript have improved the paper. The necessary open questions were clarified. However, there are still many open aspects in regard to formatting, spelling and grammar which should be checked once more.

Author Response

Thank you very much for your review. Please see the attachment.

Author Response File: Author Response.pdf