Scene Equipment Saving and Loading Method for Digital Twin Workshop
Round 1
Reviewer 1 Report
Dear Author
The content of this paper is complete, but the structure as scientific writing needs to be rearranged. The main topics of a scientific paper include; Introduction, Methods and Materials, Results and Discussion, Conclusions and Future Plans. We suggest that this article be rearranged according to these main topics. A lot of information has been conveyed, but it has not been placed according to the rules in scientific writing.
Comments for author File: 
Comments.pdf
The English in this paper as a whole is good, but there are some parts that need to be rearranged so that they are easy to understand.
Author Response
Thank you for your valuable comments, please find our response in the attached file.
Author Response File: Author Response.pdf
Reviewer 2 Report
Referencing is not correct. They must be improved. Referencing like S. Liu[6] or H. Jiang [7] is absolutely wrong.
Very length literature review without any real value
The paper length is not appropriate. It should be summarized and presented in a logical and coherent manner
Case study is too confusing and lacks the narrative or a step-by-step approach
Conclusions should be summarized and revised
Language must be improved. Very long and ambiguous sentences are present. Wrong use of punctuations, capital letters, grammar, etc. is abundant.
Use the word sections instead of chapters. I think the authors have copy pasted the dissertation here.
Author Response
Thank you for your valuable comments, please find our response in the attached file.
Author Response File: Author Response.pdf
Reviewer 3 Report
The paper is well written and well structured. It describes an important topic about digital twin workshop. The case study in the end culminates the methodology well and applies all introduced concepts. There are very few minor adjustments that are required which can increase the potential publication chances for the paper.
1. Please get your article proof read from a native english speaker. There are some grammatical mistakes in few figures as well as text.
2. On page 3 and page 4, some paragraphs are starting from 'The above study says this or that'. Please rephrase as no connection to any previous text exists.
3. In Figures 9 and 10, change the font colour of digits on bars. They are not readable.
Please get your article proofread from a Native English Speaker.
Author Response
Thank you for your valuable comments, please find our response in the attached file.
Author Response File: Author Response.pdf
Reviewer 4 Report
I want to thank the editor for the chance to review this contribution. This paper investigates the data flow management in digital twin workshop and, in particular, how to increase the efficiency in the saving and loading method for workshop data collection in presence of huge heterogeneity of data types. Please find some of my concerns related to this work hereafter:
-) Please consider to provide a short definition of the digital twin workshop when explaining the intentions of the paper
-) In the abstract the adoption of historical data to optimize workshop productivity in mentioned; however, digital twin is much more famous for exploiting real-time data to take dynamic decision to optimize the workplace. How historical data and real-time data can be exploited together in this work to optimize managerial decisions?
-) The Digital Twin concept works with real-time data, it can simulate the process to study the possible bottlenecks with the current resources and eventually propose some changes. Hence, I do not understand the link between the digital twin concept and the adoption of old historical data for bottleneck detection, since currently it can be made on-time.
-) Did authors already start to explain the background of this research in the introduction? In the introduction, authors should state the reason why this research can be worth of being pursued with some recent data and statistical analysis on the time spent on data management for example. I suggest authors to postpone the review of literature in the apposite section, and dedicate more attention in the introduction to justify why this work is worth of being investigated and the novelty of their research rather than provide some examples of data management.
-) In the introduction, a simple example of scene equipment saving and loading method may help reader to better understand the problem.
-) In the literature review, a table with the cited works can help readers to understand the commonalities and the differences between this work and the previous ones. Furthermore, it helps authors to understand if the references cited in this version are all necessary and related to their work.
-) Little is said about the multi-source sensors also for human digital twin tracking. Humans, as well as machines, can be tracked and monitored in real-time to provide feedback to workers' behavior, work and health conditions. In such a work, it would add another level of difficulties that authors could deal with their framework.
-) Authors stated that many prior studies just deal with a posteriori analysis and historical data. Then, how the present work differentiates from the work of M. Subramaniyan [25] and [24] which as historical data-based for decision making?
-) In my opinion from reference [31], authors started to be much more focused on their research and prior works on the topic. Hence, I suggest authors to focus more on this point and cut some not so useful reference in the first part of the paper such as in introduction and first part of literature review, which may be linked to the topic, but no focused such as the one reported since [31].
-) Despite this work presents a framework on data capturing and data management, I missed the link with the real environment and the hardware adopted for sensing data in real-time. How this framework can be implemented in practical cases and which hardware is it necessary?
-) Authors report this sentence at page 5: "Any scene or equipment in a virtual workshop can be seen as a DT Object". I would rather say that every object that can be represented through its digital representation and that is able to directly affect the behavior of the real counterpart can be considered such as a DT of the object. To be considered as a DT, there is the need to close the data collection and information provision loop from and to the real object.
-) Again in the Layer 3, Operators and workforce in general are missing. Did authors consider the opportunity to include them in their work? If not, this should be stated as a limitation of the current work and possibly a future development in the conclusion; otherwise, authors should have a look to the concept of human digital twin, or digital twin of the person, and try to include it as well as machines and warehouses in the framework.
-) Why authors decided the framework needs to have 5 layers? Layer 4 and 5 seem very close to me, the differences between the layers should be better defined and the reason why there are 5 distinctive layers need to be provided. Moreover, is it an original framework or is there another framework that inspired this work as an extension of an existing framework? This may better justify the existence of 5 layers.
-) In Table 1 please insert the acronyms in the explanation such as "Workshop equipment (WE) belong to workshop object (WO)"
-) Authors from here on started to state that they reported "Equation", however "Equation (1)" to me is not a proper equation with the "=" sign in it. Please consider to call them "formula" or "formulae". However, if authors can provide an example of another work where these formulae are called equations, I can accept this definition. This is valid also for "Equation (2)" and so further.
-) Please provide more insight on the concept of fixed and roam viewer. Are these concepts completely new or were they already been used previously? I've only experienced sensor-based data capturing from static sensors for DT creation so far, more insights on this concept can help also the final decision maker on which sensors might be implemented in the field.
-) Despite this work represents a framework for data management for DT creation in the process of saving and loading, I do really miss a concrete adoption that can provide more insight on the benefits of the proposed framework compared to existing ones. Authors provide a virtual simulation and a random scenario creation to state its benefits; however, has this framework already been tested elsewhere or is it just a concept that still need to be proved?
-) The conclusion of the work can be extended with some limitations, future agenda and challenges for the future. Which are the possible benefits of implementing such model in complex scenarios? Human presence has not been addressed by this paper, some future development in this way can be appreciated since digital twin will not substitute the presence of human workers but conversely can provide additional benefits ads well, which are the challenges in this direction according to authors?
Please note that the references are double numbered with two lists (e.g., 1. 1. Tao, F., et al., Digital Twin in Industry: State-of-the-Art. IEEE TRANSACTIONS ON INDUSTRIAL INFORMATICS, 2019. 15(4): p. 2405-2415.)
Please note that even the Disclaimer/Publisher’s Note is numbered and it should not.
I hope my comments can help authors to submit a better version of their current work. Please consider to include some practical insights that can help readers to understand the problem and the possible benefits of your work.
Kind regards.
The level of English is quite good. Please have a review of the text to find some typos such as full stop and missing capital letters. An overall review of the English can help the reader to better understand the concept, do not miss to state the acronyms you used.
Author Response
Thank you for your valuable comments, please find our response in the attached file.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Ok, thank you for revising according to our suggestions, hopefully it can be published soon.
Comments for author File: Comments.pdf
Reviewer 4 Report
I appreciated the fact the authors accepted my suggestions to improve the quality of their work, hence, I can suggest its acceptance. The inclusion of human factors in the limitations and in the future perspectives of the work is a great choice, however, I expected authors could give a bit more space on this important topic rather than just add it in the limitation of the current work. Probably, a subsection on this topic during the explanation of the different nature of sources could introduce the reader to the difficulties of this challege. Best regards.
