PONE-D-19-29325

Propagation Law of Ultra-wideband Radar Waves in Coal

PLOS ONE

Dear Dr. Zhang,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

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Marco Lepidi, Ph.D.

Academic Editor, PLOS ONE

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two independent reports have been collected for your submission. Both the reports are generally encouraging, but recommend major improvements.

Please, carefully revise your manuscript according to the questions and/or suggestions provided by the reviewers.

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Marco Lepidi

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Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Partly

Reviewer #2: Partly

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2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

**********

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Reviewer #1: Yes

Reviewer #2: Yes

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4. Is the manuscript presented in an intelligible fashion and written in standard English?

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Reviewer #1: No

Reviewer #2: No

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5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: See attached for completed comments.

The key contribution of this paper is that it reports the effects of EM wave frequencies on two fundamental parameters or properties: resistivity and dielectric permitivity for different rank coal samples. I am not quite sure one can claim the outcome/results of the lab testing of these parameter can be declared as “Law”. The claim of the Ultra-wideband radar wave is also arguable as the radar wave used is not necessarily ultra-wideband but the frequency was varied from 100 Mhz – 1000 MHz. Otherwise they would not be able to obtain the parameter variations with frequencies. Based on these measurements, it also derived the EM wave attenuation and speed variations with frequencies for different rank coal samples.

The speed is computed by using the simplified version of the wave speed formula (3). I suggest you may also compute with a more accurate formula such as (Zhou and Fullagar, 2001):

So that it may get different values to the simplified one. Surely the results may do not change much as the frequencies used are relatively high and the approximated version could provide sufficient accuracy.

One of the objectives of the paper is to use GPR for detection of mine trapped personnel after a coal mine disaster. With a frequency ranging from 100 MHz to 1000 MHz, I wonder what kind of penetration capability it will be although the paper claims, in Introduction, the GPR has “strong penetration”. The detection examples in Figures 11 & 12 are simplified too much with no practical use at all. At most, you only illustrate you can estimate the distances of reflection objects without knowing which direction they come from. Such ability is well illustrated in seismic and GPR textbooks. GPR is relatively matured technique. Is there any successful examples such as from controlled experiments in coal mine environment? I guess not. Even if you can receive the reflections from trapped personnel, you need to address the issue such as how to differentiate the human reflections from many other reflections from imhomogeinities of the strata, underground equipment and objects. If you cannot resolve this issue, your GPR measurements have no use to this particular applications.

Based on my above comments, I suggest the author concentrated on the property measurement report rather than try also to address the trapped human detection. Properly understanding the property of coal samples for different frequencies is a good contribution to the literature.

In addition, please improve your English expression of the paper to ensure communicate your finding to your reader effectively. This can be achieved by asking a native English speaker or English Editing services to help you before submit your paper.

Reference

Zhou, B. and Fullagar, P.K., 2001, Delineation of sulphide ore-zones by borehole radar tomography at Hellyer Mine, Australia: Journal of Applied Geophysics, 47, No 3-4, pp.261-269.

Reviewer #2: General remarks: The paper presents data from laboratory testing of electrical properties of various coal samples taken from Chinese mines. Test were performed on a commercial Broadband Dielectric Spectrum Test System -Concept-80. It allows to determine the values of dielectric permittivity and specific resistivity of grinded coal samples subjected to the electromagnetic fields in wide frequency spectrum. On the base of laboratory data a set of approximating equations showing the change of electric properties in frequency domain ranging from 100-1000 MHz was obtained. These equations together with known from EM theory formulas for EM waves speed and attenuation were used for modeling and studying the process of radar waves propagation in a coal seam and reflection from the miners entrapped in collapsed tunnels. The modeling concept assumes that a radar transducer with dominating frequency MHz will be lowered through a vertical or inclined rescue borehole to the depth of coal seam with mining opening. It is assumed that in not collapsed part of tunnel only miner is present. Thus on the path of radar wave from transducer to a human we have only one geological interface reflecting the radar signals (coal-air) and one connected with human body. The human reflector can be located in various distances from the tunnel face. This factor was included in analyzed geometrical model. On the base of modeling results the authors of the paper conclude that a reliable human origin reflected radar signal can be measured when a distance between human and transducer do not exceed 5 m.

Although the concept and research data presented in the manuscript are very interesting and valuable scientifically it needs a thorough revision. There are a lot of deficiencies. Starting from the title, the next parts of manuscript (abstract, introduction and conclusions) in my opinion should be completely re written (my general remarks can be used as a new abstract in the paper). The rest of them need to be corrected. I suggest to remove figures 1 and 2 from the paper. They do not bring nothing and are detached from the content of the paper. Some other figures also need corrections. I recommend to send the manuscript back to authors for major revision. My detailed remarks are included in a word processor file, attached to the revision. I hope that they help the authors to correct the manuscript

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Reviewer #1: No

Reviewer #2: No

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Attachments

Attachment

Submitted filename: Review Comments.pdf

Attachment

Submitted filename: PONE-D-19-29325_reviewer-ak7.docx

PONE-D-19-29325R1

Propagation of Ground Penetrating Radar Waves in Chinese Coals

PLOS ONE

Dear Dr. Zhang,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

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Kind regards,

Marco Lepidi

--------------------------------------------------------------------------------------

Marco Lepidi, PhD

Associate Professor, Academic Editor of PLOS ONE

Dipartimento di Ingegneria Civile, Chimica ed Ambientale

Università degli Studi di Genova (Italy)

Mail: Marco.Lepidi@unige.it

Website: http://www3.dicca.unige.it/mlepidi/index.html

Google Scholar: http://scholar.google.it/citations?user=uePAdVUAAAAJ&hl=it

Additional Editor Comments (if provided):

Dear Authors,

two reports have been collected for your submission from the same reviewers of the first round. Both the reports are generally positive, but one of the report still recommends major improvements.

Please, take this last opportunity to carefully revise your manuscript according to the questions and/or suggestions provided by the reviewers.

Best regards

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: (No Response)

Reviewer #2: All comments have been addressed

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Partly

Reviewer #2: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: No

Reviewer #2: No

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: My concern on how to differentiate the radar reflections from many other reflections from inhomogeneities of the strata, underground equipment and objects has not been properly addressed. I fully understand that human is different from strata and equipment. But there are so many situations that you can observe similar reflections to those from human bodies. For example, will you be able to tell the difference of human reflections from the waterbody reflections in the strata? This is related to multi-solutions of geophysical problems – the same observation can be caused by many different situations. In addition, I have not been convinced by the authors’ response that their prototype radar system with a gyro can tell the direction of received radar waves, unless their radar system is a directional system. Can you provide an example of the testing results for trapped humans using your prototype radar system. Otherwise, there is a 360 degrees ambiguity. If you want to use the radar method for detection of the trapped miners in disasters, you have to address and discuss these issues.

I don’t think your paper has been properly edited by an academic editing people as there are many Chinglish expressions remained – some of them are in the attached marked manuscript. It is interesting to see that you just copied and pasted the reviewer’s comments as your abstract without changing a word.

Reviewer #2: The manuscript has been deeply improved and all my suggestions have been considered. Nevertheless, I've noticed some minor errors or "bugs" which have to be removed before publication. I attach a revised manuscript indicating noticed "bugs". After removal of them the manuscript can be accepted for publishing.

**********

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Reviewer #1: No

Reviewer #2: No

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files to be viewed.]

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Attachments

Attachment

Submitted filename: PONE-D-19-29325_R2_reviewer2.docx

Attachment

Submitted filename: PONE-D-19-29325_R1_reviewer.pdf

PONE-D-19-29325R2

Propagation of Ground Penetrating Radar Waves in Chinese Coals

PLOS ONE

Dear Dr. Zhang,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

We would appreciate receiving your revised manuscript by Apr 30 2020 11:59PM. When you are ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter.

To enhance the reproducibility of your results, we recommend that if applicable you deposit your laboratory protocols in protocols.io, where a protocol can be assigned its own identifier (DOI) such that it can be cited independently in the future. For instructions see: http://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols

Please include the following items when submitting your revised manuscript:

• A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). This letter should be uploaded as separate file and labeled 'Response to Reviewers'.
• A marked-up copy of your manuscript that highlights changes made to the original version. This file should be uploaded as separate file and labeled 'Revised Manuscript with Track Changes'.
• An unmarked version of your revised paper without tracked changes. This file should be uploaded as separate file and labeled 'Manuscript'.

Please note while forming your response, if your article is accepted, you may have the opportunity to make the peer review history publicly available. The record will include editor decision letters (with reviews) and your responses to reviewer comments. If eligible, we will contact you to opt in or out.

We look forward to receiving your revised manuscript.

Kind regards,

Marco Lepidi

--------------------------------------------------------------------------------------

Marco Lepidi, PhD

Associate Professor, Academic Editor of PLOS ONE

Dipartimento di Ingegneria Civile, Chimica ed Ambientale

Università degli Studi di Genova (Italy)

Mail: Marco.Lepidi@unige.it

Website: http://www3.dicca.unige.it/mlepidi/index.html

Google Scholar: http://scholar.google.it/citations?user=uePAdVUAAAAJ&hl=it

XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

Dear Authors,

The two reviewers have reconsidered your submission. One of them is fully satisfied, the other is still asking for some minor improvements.

Please, reply (and/or carefully revise your manuscript according) to the questions and/or suggestions provided by the second reviewers.

Best regards

Marco Lepidi

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: (No Response)

Reviewer #2: All comments have been addressed

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Partly

Reviewer #2: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: No

Reviewer #2: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: No

Reviewer #2: No

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: See attached comments

I don’t think the authors have addressed my previous comments properly.

The authors replied

1> We can distinguish the return wave is reflected by the human or the formation water. There are two reasons for this. The first is that the electrical parameters of water are significantly different from the electrical parameters of the human body. The second is that the human's reflected waves are loaded with regular heartbeat signals.

Theoretically what you said is correct. However, in practice, how do you differentiate the human reflection from the formation water body reflection from recorded radargrams? Please provide your method in the paper. Can the radar record show or detect human’s heartbeats? What is the resolution of the GPR system? Can you please provide any evidence or references on how your GPR can detect heartbeating? Please write your paper more scientifically, not with statements without support.

2> As the reviewer said, our radar system is a directional system. As shown in Figure 1, the radar structure includes the transmit and receive window. The size of the window is 70 mm × 50 mm. Experts from the China National Key R & D Project team tested our radar prototype at Jining No. 2 Coal Mine. One of the test scenarios is shown in Figure 2, and the test results are shown in Figure 3.

You only provide numerical examples which prove nothing as any different objects can cause radar reflections theoretically. Your Figure 3 in your reply also shows nothing – why are there no actual radar data presented to support your conclusion? How good is the directionality of your radar system? What is the radiation pattern? Why don’t you include a real data example in this paper for human detection or event to see the heartbeating?

3> The article has been edited by academic editing with the native language. We have provided the certificate of english editing in the previous reply. If required, we can invite academic editors to make it more standard. After reading the reviewers' comments, we all think that it is very perfect. It is more suitable as an abstract for a dissertation. Therefore, we have completely used the reviewer's comments as a new abstract.

I have made some suggestions in the last review but you totally ignored my suggestions and believe that your English is fine! You may pay some attention to the following comments/suggestions (I am sure there are more in the paper) :

1. Line 29: Prefer to change “the authors of the paper conclude” to “, it is concluded”. The reviewer’s writing is ok, but I don’t think the authors of the paper should use similar expression.

2. Line 31: Not quite sure what exact you mean by “do not exceed 5-8 m”! Do you mean it should not exceed 5m or you really mean it should not exceed 8m. Or you mean the distances between 5m and 8m are ok. How did you derive these number? Or is this because you only modelled the data up to 8m?

3. Line 43: I am not sure you have used “particularly significant” and “major” correctly for these events – please check your original Chinese meaning with the corresponding English.

4. Line 67/8: “Fan and Jia et al.” -> “Fan et al.”

5. Line 69: “Fan and Chang et al.” -> “Fan et al.”

6. Line 82: “Peng” -> “Peng et al.”

7. Line 85: “Xu” -> “Xu et al.”

8. Line 88: “Emslie et al.” -> “Emslie and Lagace”

9. Line 94: “Luo and Stolarczyk et al.” -> “Luo et al.”

10. Line 106: “Dielectric properties measurement” ->”Dielectric property measurement”

11. Line 108-110: Change “in” to “from”.

12. Line 130: “followed similar regularities” -> “follow a similar trend”. Using “regularity” is very Chinese!

13. Line 139: “larger” -> “higher”. The constant is “higher” not “larger”.

14. Line 160: “large” -> “high”. We normally say the attenuation is high or low not large or small in English!

15. Line 184, 188, 191: “large”->”high”; “small” ->”low”.

Reviewer #2: I would response in point 5 "yes" but I have noticed some, following typographical errors in the manuscript:

line 102 ........ radar waves in coal "are" constructed (should be "is" constructed),

line 132 ........ largest "one" (should be plural "ones"),

line 216 ......... is relatively (should be "relative").

Figure captions:

Fig.5 variations of tesed coals (should be "tested"),

Fig.9 I - schematic "of" illustration of disaster (should be schematic illustration of disaster),

Fig.9 II - Schematic "of simplified" of physical model (should be schematic physical model),

Fig.11 - Relationship between (or a plot) between............. Dual expression. Should be only one eg. Relationship between amplitudes........ (remove "or a plot").

Notice to editor:

Although the current title of manuscript has been my proposal (revision 1) I suggest the editor to consider the following change "A concept of borehole radar for rescuing miners trapped in deep coal mines". After revisions made this title reflects better the content of the paper. In my opinion it could also increase the interest in the article. I leave decision upon the editor.

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7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: No

Reviewer #2: No

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files to be viewed.]

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Attachments

Attachment

Submitted filename: R2 Comments.pdf

Propagation of Ground Penetrating Radar Waves in Chinese Coals

PONE-D-19-29325R3

Dear Dr. Zhang,

We are pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it complies with all outstanding technical requirements.

Within one week, you will receive an e-mail containing information on the amendments required prior to publication. When all required modifications have been addressed, you will receive a formal acceptance letter and your manuscript will proceed to our production department and be scheduled for publication.

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With kind regards,

Marco Lepidi, Ph.D.

--------------------------------------------------------------------------------------

Marco Lepidi, PhD

Associate Professor, Academic Editor of PLOS ONE

Dipartimento di Ingegneria Civile, Chimica ed Ambientale

Università degli Studi di Genova (Italy)

Mail: Marco.Lepidi@unige.it

Website: http://www3.dicca.unige.it/mlepidi/index.html