Planning of Electric Taxi Charging Stations Based on Travel Data Characteristics

Round 1

Reviewer 1 Report

In this paper, authors studied electric taxi (ET) and planning of charging stations. Authors devised a scheme for mining latent semantic correlation based on ET trajectory. Basically, the motivation of the paper is good and the proposed method is novel. Also, authors implemented the proposed scheme through extensive experiments with practical settings and scenarios. Moreover, the organization of the paper is good.

To improve the paper, the below minor parts are recommended to be modified by authors.

1) In Section 5, authors need to provide more detailed information of experiment environment such as system settings, used tools, software, hardware, the brief reason why they utilized those settings, etc.

2) It is recommended that authors will investigate more wide range of related works including various types of vehicles and add those studies to the manuscript. There are a few suggested works.

-H. Kim, L. Mokdad, J. Ben-Othman, "Designing UAV Surveillance Frameworks for Smart City and Extensive Ocean with Differential Perspectives," IEEE Communications Magazine, vol. 56, no. 4, pp. 98-104, 2018.

-H. Kim, J. Ben-Othman, L. Mokdad, "UDiPP: A Framework for Differential Privacy Preserving Movements of Unmanned Aerial Vehicles in Smart Cities," IEEE Transactions on Vehicular Technology, vol. 68, no. 4, pp. 3933-3943, 2019.

In particular, authors can also investigate critical studies which were published in electronics.

3) In Section 6, authors can give more description for future research challenges, issues and works for potential researchers.

4) Authors can check if there are minor typos in the manuscript. For example, the author name has no space between “IEEE” and “and”. (IEEEand Xue ..)

Author Response

1) In Section 5, authors need to provide more detailed information of experiment environment such as system settings, used tools, software, hardware, the brief reason why they utilized those settings, etc.

Response： Thank you very much for the valuable comments from the reviewer. The author has carefully checked and revised the paper according to the comments. Your comments have played a vital role in improving the quality of this paper.  

The author further discusses the suggestions put forward by the reviewers in section 6. The author uses MATLAB software for simulation calculation. The function of MATLAB is powerful enough to extract the semantic information of the driving track of electric taxi and cluster it.

2) It is recommended that authors will investigate more wide range of related works including various types of vehicles and add those studies to the manuscript. There are a few suggested works.

-H. Kim, L. Mokdad, J. Ben-Othman, "Designing UAV Surveillance Frameworks for Smart City and Extensive Ocean with Differential Perspectives," IEEE Communications Magazine, vol. 56, no. 4, pp. 98-104, 2018.

-H. Kim, J. Ben-Othman, L. Mokdad, "UDiPP: A Framework for Differential Privacy Preserving Movements of Unmanned Aerial Vehicles in Smart Cities," IEEE Transactions on Vehicular Technology, vol. 68, no. 4, pp. 3933-3943, 2019.

In particular, authors can also investigate critical studies which were published in electronics.

Response：The author adds further discussion in the introduction.  It also includes "electronics" related papers.  In the section of references, references provided by reviewer are also included, which are references [8] and [9] respectively.  

3) In Section 6, authors can give more description for future research challenges, issues and works for potential researchers.

Response：In last section, the author elaborates the future research in detail.  The difficulties and challenges that may be encountered are also discussed. 

4) Authors can check if there are minor typos in the manuscript. For example, the author name has no space between “IEEE” and “and”. (IEEEand Xue ..)

Response：The author has revised it. The space is added.

Thanks again to the reviewer. Thank you very much.

Author Response File: Author Response.pdf

Reviewer 2 Report

Dear authors, while the presentation is nice in shape, there are few comments and/or suggestions to strongly improve the manuscript. While there is some interest in this type of research, Please reconsider the paper as:
1.     The significance of the study is not clear to me and there is a serious literature review gap in this paper. The literature state-of-the-art contains too few references. I strongly consider that the distinguished authors did not pay attention to the other relevant references. Perhaps, the related work section can be extended with 15-20 additional relevant sources (IEEE, Springer, Elsevier, MDPI). Multiple cited references are inappropriate and must be explained (please reconsider [3-5], [6-8], [9-11] etc.)
2.     Clarify better the advantages of this paper in the introduction section because in the literature a lot of recent papers consider the same proposed approach.
3.     I strongly recommend the authors have a separate section for the literature review and to discuss the drawbacks of existing works.
4.     The method itself is not well described. There are a number of (simple) mathematical quantities that are defined, but their use in the proposed planning model is not precisely defined.
5.     Moreover, the authors must present the limitation of the considered method.
6.     The conclusion looks like a summary. It would be better to rewrite it and add many effective results in the Conclusion section.
7.     The results are abundant but the results' analysis is not enough. However, I cannot see deeply analysis related to them and cannot understand the meaning of results. Please add more analysis.
The authors must strongly consider the aforementioned suggestions and resubmit.

Author Response

1.The significance of the study is not clear to me and there is a serious literature review gap in this paper. The literature state-of-the-art contains too few references. I strongly consider that the distinguished authors did not pay attention to the other relevant references. Perhaps, the related work section can be extended with 15-20 additional relevant sources (IEEE, Springer, Elsevier, MDPI). Multiple cited references are inappropriate and must be explained (please reconsider [3-5], [6-8], [9-11] etc.)

Response：Thank you very much for your valuable comments. The author has carefully checked and revised the comments. Your comments have played a vital role in improving the quality of this article. Thank you very much.

The author further revised the references and review, and reconsidered the references [3-5], [6-8], [9-11].

2. Clarify better the advantages of this paper in the introduction section because in the literature a lot of recent papers consider the same proposed approach.

Response：The author makes corresponding supplementary explanations in the introduction.

3.I strongly recommend the authors have a separate section for the literature review and to discuss the drawbacks of existing works.

Response：The author adds an separate section in section 2. In section 2, the author reviews and discusses the existing works.

4.The method itself is not well described. There are a number of (simple) mathematical quantities that are defined, but their use in the proposed planning model is not precisely defined.

Response：In the section 6, the author further expounds the calculation and analysis, and explains the application process of the method in this paper.

5. Moreover, the authors must present the limitation of the considered method.

Response：The limitations and shortcomings of the proposed method are revised and supplemented in the last part of the paper.

6. The conclusion looks like a summary. It would be better to rewrite it and add many effective results in the Conclusion section.

Response：According to the opinions of reviewers, the author rewrites the conclusion and adds corresponding contents.

7. The results are abundant but the results' analysis is not enough. However, I cannot see deeply analysis related to them and cannot understand the meaning of results. Please add more analysis.
The authors must strongly consider the aforementioned suggestions and resubmit.

Response：The author makes further explanation and revision in this part, and adds the analysis part.

Thank you again for your valuable comments.

Author Response File: Author Response.pdf

Reviewer 3 Report

The presented study in this manuscript seems to have a decent organization and includes a detailed mathematical model. However, the introduction and literature survey parts seem to be not connected with many wrong employments of references. The results part is more disappointing as it does not highlight any “proofed or evaluated” claims. It was expected to see more valuable contributions in terms of electric taxi charging stations planning. It was not clear that the authors are trying to study the data either from 2019 in Hangzhou city or from 2008 in San Francisco! Also, the manuscript has a poor English language presentation (structure and grammar), especially the first section.

The presented study failed to address the following:

• What is it that the authors want to study and deliver? It should be stated clearly as the main objective!
• What is the main contribution to this study?
• What is the impact of this study on future electric taxi planning?
• Where is the optimal planning (optimization part)?

As such, it would be difficult for the reviewer to accept this study for publication in this shape!

For future submission, the reviewer would suggest the following changes and questions be addressed and applied to maintain a comprehensive study:

1. Line 25: it is better to add Electric Taxi as one of the keywords instead of “ET”.
2. Lines 28-32: the connection between the first two sentences seems to be odd! The same applied to the whole paragraph. (Jumping between different topics without any smooth transition).
3. Line 52: “Some researchers”, like who?
4. Lines 53-55: please support your claim with some references.
5. Lines 61: incomplete sentence!
6. Lines 59-64: are the authors referring to their study or someone else? Please clarify.
7. Lines 71-72: what are the three different types? The same applies to the “three types” stated in line 77!
8. Lines 79-80: the sentence is not clear! What problem is to be solved? Everything should be clarified.
9. Line 184 and forward: please maintain the same referencing format.
10. Line 322: why does it say, San Francisco? Shouldn’t it be Hangzhou city?
11. Figure 1: it is recommended to set the borders of the studied area as necessary. Or at least highlight the most used routes.
12. Table 2: it should be represented in a better way.
13. Lines 460-462: the sentence contradicts what is in lines 319-321.

Author Response

• What is it that the authors want to study and deliver? It should be stated clearly as the main objective!
• What is the main contribution to this study?

Response：Thank you very much for your valuable comments. Your comments have played a vital role in improving the quality of this article. Thank you very much. The author has carefully checked and revised according to the opinions, and the specific answers are as follows.

The main contribution to this study is expressed as follow. Based on the big data of electric taxi driving trajectory, a vector space model is established, and the fast semantic calculation of large-scale trajectory data matrix is realized by random projection method. Then, combined with the spectral clustering method, the urban spatial spectral clustering of latent semantic correlation mining is realized. According to the spectral clustering results, the charging station planning of urban space is realized, the costs are considered in the planned charging station, and finally the economic optimal planning result is realized.

• What is the impact of this study on future electric taxi planning?

Response：The main research ideas of this paper are as follows: Based on the big data of electric taxi trajectory, this paper extracts potential semantic information, which reflects the driving heat of electric vehicles in different regions, so as to reasonably plan the distribution of charging stations.

The analysis method proposed in this paper can be used for trajectory clustering and can also find the hot spots of electric taxis, so as to provide decision support information for rational planning of charging stations.

• Where is the optimal planning (optimization part)?

Response：The results of charging station planning in this paper are explained by a specific example.

Assuming that the following figure is an urban space, the space can be divided into 36 grids. Electric vehicles travel in the grid, and many driving tracks of electric vehicles can be obtained in each grid.

Please refer to the attachment "Reply to the Reviewer 2" for the specific coordinate diagram.

Based on the obtained driving trajectory, this paper carries out vector space modeling, extracts the latent semantic information contained in the trajectory data through the fast semantic calculation method, and then realizes the mining of latent semantic correlation information through the spectral clustering algorithm, so as to realize the clustering of grids. Through calculation, if grid 2, grid 7 and grid 11 belong to the same cluster (as shown in Fig. 3, Fig. 4 and table 2 in the text), then considering various costs, calculate the economy of each grid (as shown in Table 5 in the text) by using formula (16) in the text, and optimally rank different grids according to economy to obtain the planning scheme of charging station.

Therefore, the charging station planning method given in this paper comprehensively considers the driving track characteristics and economy.

As such, it would be difficult for the reviewer to accept this study for publication in this shape!

For future submission, the reviewer would suggest the following changes and questions be addressed and applied to maintain a comprehensive study:

1.Line 25: it is better to add Electric Taxi as one of the keywords instead of “ET”.

Response：The author modified it. “Electric Taxi” instead of “ET”.

2.Lines 28-32: the connection between the first two sentences seems to be odd! The same applied to the whole paragraph. (Jumping between different topics without any smooth transition).

Response：The author has modified it to make its expression more smooth.

3.Line 52: “Some researchers”, like who?

Response：It is marked here as a reference [15].

4.Lines 53-55: please support your claim with some references.

Response：The author annotates here.

5.Lines 61: incomplete sentence!

Response：The author makes a supplementary explanation.

6.Lines 59-64: are the authors referring to their study or someone else? Please clarify.

Response：The author added a note in this part, which is the research content of reference [18].

7.Lines 71-72: what are the three different types? The same applies to the “three types” stated in line 77!

Response：The three types of line 71-72 are the contents of reference [20]. The three different types are：slow charging mode, battery swapping mode and fast charging mode.

The “three types” stated in line 77 was studied in reference[22]. The author has revised it.

8.Lines 79-80: the sentence is not clear! What problem is to be solved? Everything should be clarified.

Response：It is the research content of reference [22], which has been modified and supplemented by the author.

In order to improve the electrification level of smart cities, literature [22] optimizes the combination of EV chargers. The uncertainty of EV load is also considered in the research, and the EV load is modeled as a random process, and then particle swarm optimization algorithm is used to solve the nonlinear random problem.

9.Line 184 and forward: please maintain the same referencing format.

Response：The author modified the format of references. It is checked and modified elsewhere in the text.

10.Line 322: why does it say, San Francisco? Shouldn’t it be Hangzhou city?

Response：The author revised it accordingly. It is Hangzhou city.

11.Figure 1: it is recommended to set the borders of the studied area as necessary. Or at least highlight the most used routes.

Response：The borders of the studied area of Figure 1 is given.

The urban map area is grided. The range of the studied area is [120.065817, 120.235709] in longitude and [30.179788, 30.337624] in latitude. This part divides the urban area into a single grid with size 0.003 degree in longitude and 0.003 degree in latitude.

12.Table 2: it should be represented in a better way.

Response：The author modified Table 2 and expressed it graphically, which can more clearly express the passing times of vehicles. After modification, Table 2 is represented in the form of Figure 3 and Figure 4.

13.Lines 460-462: the sentence contradicts what is in lines 319-321.

Response：The author further revised it.

   Thank you again for your guidance. Your comments play a vital role in improving the quality of the paper.

Thank you very much.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The reviewer has no further comments, the authors have satisfactorily addressed most of my comments.

Reviewer 3 Report

Thank you for clarifying and addressing the provided comments.
The numbers in Figure 4 can be presented in a better way.