Fault Detection of Landing Gear Retraction/Extension Hydraulic System Based on Bond Graph-Linear Fractional Transformation Technique and Interval Analytic Redundancy Relations
Round 1
Reviewer 1 Report (Previous Reviewer 2)
In this work is presented a fault detection scheme applied to a landing gear retraction/extension hydraulic system by means of bond graph-linear fractional transformation technique and interval analytic redundancy relations.
The work is well organized and the results are promising, however, there are some issues that have to be addressed.
1. Please avoid to writing in a personal, i.e., "...we introduce linear fractional transformation technology ..." (line 17). It is better if this sense is written as "This work lies on the introduction of a linear ....". Also. check all the manuscript in order to replace those senses where is it written in a personal way.
2. Gears are widely used in several systems, the use of gears is preferred to decrease the rotational speed as well as increase the mechanical power. In this sense, it is suggested to include in the Introduction section a brief description about how important are gears/gearboxes as a power transmission systems, as well as, a brief discussion about those works where the assessment of gearbox faults has been performed. Please consider the following references to be included in this work: https://doi.org/10.1177%2F0954406217721727 ; https://doi.org/10.1177%2F1748006X18768701
3. The novelty and contribution are not clear, commonly, the last paragraph of the introduction section is used to give a detailed description of the novelty and contribution, please consider to reformulate the last part of Introduction Section in order to be more clear about the aims of this work.
4. A step-by-step flow chart of the carried out methodology is missing, the authors have to consider including a flow chart of the proposed method in order to understand the different stages that are performed.
5. In table 4 there are several cells that are highlighted with a specific color, please be clear and include a detailed explanation if the use of colors contributes to understand something, if not, please avoid to use different colors in Tables.
6. The Conclusion section must be complemented, probably the authors may include or mention what are the main advantages of the proposed method and also the disadvantages or limitation may be mentioned .
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report (Previous Reviewer 3)
In this manuscript, there are some weaknesses through the manuscript which need improvement. Therefore, the submitted manuscript cannot be accepted for publication in this form, but it has a chance of acceptance after a major revision. My comments and suggestions are as follows:
1- Abstract gives information on the main feature of the performed study, but a couple of sentences about the obtained results must be added.
2- Authors must clarify necessity of the performed research. Research questions, aims and objectives of the study must be clearly mentioned in introduction.
3- The literature study must be enriched. In this respect, authors must read and refer to the following papers: (a) https://doi.org/10.1016/j.engfailanal.2017.07.011 (b) https://doi.org/10.1016/j.automatica.2018.08.006 and other relevant research works.
4- The structure of the paper is described at the end of introduction. It can be removed.
5- In overview of landing gear retraction system relevant literature must be added. In addition, related images from previous research can be illustrated to help the readers.
6- Researchers must refer to experimental practices available in literature with all details.
7- The main reference of all figure must be mentioned. Usually, captions of images are smaller than text font size.
8- Details of calculation of sum of squares of errors, mean-squared error, and model effect evaluation index must be added.
9- The main reference of each formula must be cited. Moreover, each parameters in equations must be introduced. Please double check this issue.
10- Standard deviation in the presented curves must be discussed. In addition, error in calculation must be considered and discussed.
11- In its language layer, the manuscript should be considered for English language editing. There are sentences which have to be rewritten.
12- The conclusion must be more than just a summary of the manuscript. List of references must be updated based on the proposed papers. Please provide all changes by red color in the revised version.
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report (New Reviewer)
Dear Authors,
This work presents diagnostic bond graph using linear fractional transformation technology and uncertainty analysis theory for the landing gear retraction/extension hydraulic system. The diagnostic results for leakage of the cylinder is presented. Application of proposed method for detecting other common failures like: Failure of retraction and extension and time limits can be discussed. Also, the characteristics and nature of the failure needs to highlighted like incipient, progressive or cascading. Further, the system health need to be specified as a number duty cycles for better interpretation.Author Response
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Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report (Previous Reviewer 3)
Authors must correct the reference style. In fact, references should be described as follows:
Author 1 (Last name, First name). Author 2 (Last name, First name), “Title of Article.” Abbreviated Journal Name, Year, volume, page range.
Authors must check the reference list and correct the references according to the above-mentioned style. For instance, the correct version of Ref. [12] and [16] are as follows:
[12] Ch.D.; Nayak, P.K. Performance assessment of swarm-assisted mean error estimation-based fault detection technique for transmission line protection. Comput. Electr. Eng.2018, 71, 115-128.
[16] Nasiri, S.; Khosravani, M.R; Weinberg, K. Fracture mechanics and mechanical fault detection by artificial intelligence methods: A review. Eng. Fail. Anal. 2017, 81, 270-293.
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report (New Reviewer)
Dear Authors, The proposed diagnostic bond graph using linear fractional transformation technology and uncertainty analysis theory for the landing gear retraction/extension hydraulic system is novel and it will be helpful air craft landing gear maintenance.
Author Response
Thank you very much for your constructive comments.
This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.
Round 1
Reviewer 1 Report
In the reviewer’s opinion, the paper could have been more interesting and better organised. In general, the overall contribution remains scientifically poor and technically questionable. In more detail, the paper’s title is not very clear, as for its Abstract, since they should have avoided the use of acronyms, which reduce their readability. The keyword list seems appropriate. Section 1 cites some references, but it does not provide a sufficiently exhaustive overview and critical discussion of the state of the art of the related literature. As further remark, usually the end of Section 1 should summarise the general structure of the manuscript by briefly listing the contents of its sections. Section 2 should have addressed more details regarding the considered models and tools; in particular, it does not consider the robustness and reliability issues, due for example to uncertainty and disturbance effects, as well as the model-reality mismatch. This point is fundamental when the reliability and robustness features of the proposed solutions have to be verified and validated with respect to real engineering and safety critical systems. Therefore, the effectiveness of the methodology proposed in Section 3 remains unclear and questionable. The authors should have helped the reader to understand the novelty issues of the developed scheme. Due to these flaws, the results considered in Section 4 do not help the reader to understand the effectiveness and the efficacy of the proposed solutions. The authors reported many pictures. However, more effective metrics and performance indices should be exploited to assess the advantages of the developed techniques. Finally, Section 5 does not suggest effective open problems and future issues that could require further investigations. On the other hand, the use of acronyms and technical details should have been avoided also here, as it should remain a stand-alone part of the manuscript.
Author Response
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Author Response File: Author Response.pdf
Reviewer 2 Report
This work has been focused to the Fault Detection and Isolation of Landing Gear Retraction/Extension Hydraulic System Based on BG and GARRs, where, different progressive types of deficiencies have been studied, including the filter blockage, actuator leaks, and landing gear selector valve reversing stuck.
The proposal is interesting but some issues must be addressed.
1. The novelty and contribution have to be highlighted in the Abstract, the Introduction (include a paragraph to mention the main contribution of the work) and the Conclusion.
2. The Introduction Section may be improved by means of including a constructive discussion about those similar works that have been previously published, such discussion may be also used to highlight the contribution of this proposal.
3. Also, the Introduction may be improved by including a brief description about how important is to apply Condition Monitoring Strategies, even more in this kind of applications where catastrophic accidents may occur. In this sense, the authors can reference some of the following papers in order to mention the importance of applying condition monitoring strategies: https://doi.org/10.1109/TII.2020.2973731 ; https://doi.org/10.3390/s21248440
4. The conclusion can be improved by mentioning future work and possible real application.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
there are some weaknesses through the manuscript which need improvement. Therefore, the submitted manuscript cannot be accepted for publication in this form, but it has a chance of acceptance after a minor revision. My comments and suggestions are as follows:
1- Abstract gives information on the main feature of the performed study, but a couple of sentences about the faults in this study must be added.
2- Authors must clarify necessity of the performed research. Objectives of the study must be clearly mentioned in introduction.
3- The literature study must be enriched. In this respect, authors must read and refer to the following recent relevant papers: (a) https://doi.org/10.1016/j.engfailanal.2017.07.011 (b) https://doi.org/10.1016/j.compeleceng.2018.07.030
4- The introduction needs to be focused. Discussion needs literature comparisons. Introduction should be clear and target the fault and fault detection in question.
5- The main reference of each formula must be cited. Moreover, each parameters in equations must be introduced. Please double check this issue.
6- More real images is appreciated. Some details of calculation must be presented in a table.
7- Standard deviation is the presented curves must be discussed. In addition, error in calculation must be considered and discussed.
8- In its language layer, the manuscript should be considered for English language editing. There are sentences which have to be rewritten.
9- The conclusion must be more than just a summary of the manuscript. List of references must be updated based on the proposed papers. Please provide all changes by red color in the revised version.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
In the reviewer’s opinion, the revised paper could have been more interesting and better organised. In general, even after the revision, the overall contribution remains scientifically poor and technically questionable. The authors have not sufficiently improved the quality of the work. In fact, Section 1 does not provide a sufficiently exhaustive overview and critical discussion of the state of the art of the related literature. Section 2 should have addressed more details regarding the considered models and tools; in particular, it does not consider the robustness and reliability issues, due for example to uncertainty and disturbance effects, as well as the model-reality mismatch. This point is fundamental when the reliability and robustness features of the proposed solutions have to be verified and validated with respect to real engineering and safety critical systems. Therefore, the effectiveness of the methodology proposed in Section 3 remains unclear and questionable. The authors should have helped the reader to understand the novelty issues of the developed scheme. Due to these flaws, the results considered in Section 4 do not help the reader to understand the effectiveness and the efficacy of the proposed solutions. Moreover, more effective metrics and performance indices should be exploited to assess the advantages of the developed techniques. Finally, Section 5 is quite long; moreover, the use of itemised list reduces its readability, thus making it quite fragmentary. Moreover, it does not suggest effective open problems and future issues that could require further investigations.
Author Response
Please see the attachment
Author Response File: Author Response.pdf
