Round 1

Reviewer 1 Report

1.The authors reported four shapes of corn namely: horse tooth (trapezoidal front and back profile, with width much   larger than thickness), spherical cone (rounded in section, tapered from front to back), spherical (nearly uniform diameter, usually most ideal), oblate (flat in section, with width much larger than thickness), and irregular (obvious defect or odd shape). Please give how to defined these sizes (according to one number or ratio), please give details and insert the value of seed moisture content.

2. Do you think the archived results are suitable for another   corn variety instead of Zhengdan 958 corn variety. Please give answers if yes or if no.

3.The authors must study the effect of corn seed moisture content on the simulation results.

4. In conclusion section, the authors wrote” The results of this study can be utilized to improve the design of agricultural machinery and equipment, thus contributing to sustainable agriculture practices”. Please give examples how to   improve the design of agricultural machinery and equipment according to the obtained results.

Author Response

1.The authors reported four shapes of corn namely: horse tooth (trapezoidal front and back profile, with width much   larger than thickness), spherical cone (rounded in section, tapered from front to back), spherical (nearly uniform diameter, usually most ideal), oblate (flat in section, with width much larger than thickness), and irregular (obvious defect or odd shape). Please give how to defined these sizes (according to one number or ratio), please give details and insert the value of seed moisture content.

Reply: Firstly, I would like to thank the reviewers for their valuable comments. In conjunction with previous research this paper focuses on differentiating maize shape types by sphericity. The sphericity of horse tooth is 0.57-0.66, and the sphericity of spherical cone is 0.63-0.77, and the sphericity of spherical seed is 0.77-0.96, and the sphericity of oblate seed is 0.80-0.85, and the sphericity of irregular is 0.91-0.93. In addition, the moisture content of the maize varieties used in the trials has been mentioned in the paper. a moisture content is 12.15~15.15% (wet base).

 

2. Do you think the archived results are suitable for another corn variety instead of Zhengdan 958 corn variety. Please give answers if yes or if no.

Reply: of course, yes.

 

3.The authors must study the effect of corn seed moisture content on the simulation results.

Reply: Firstly, I would like to thank the reviewers for their valuable comments. According to the relevant literature, it is known that the moisture content of maize influences its static friction coefficient. This paper focuses on the effect of maize shape on its rolling friction coefficient, and to obtain a more accurate maize rolling friction coefficient, a more detailed calibration method according to maize shape is used, which is useful for improving the accuracy of discrete element maize simulation results. In addition, the pre-testing of the maize simulation pile-up found that the effect of moisture content on the pile-up angle of maize was mainly reflected by the static friction coefficient. Based on expert opinion, it has been shown in the paper that maize moisture content has a small effect on its rolling friction coefficient.

 

4. In conclusion section, the authors wrote” The results of this study can be utilized to improve the design of agricultural machinery and equipment, thus contributing to sustainable agriculture practices”. Please give examples how to improve the design of agricultural machinery and equipment according to the obtained results.

Reply: Firstly, I would like to thank the reviewers for their valuable comments. The main objective of this paper is to improve the simulation reliability and accuracy of the discrete element maize model through calibrated maize rolling friction, and to validate this through two stacking angle tests and one seeding row test, demonstrating that the maize modelling and parameter calibration methods used in this paper are an improvement over traditional literature method. This is mainly reflected in the fact that the simulation of seed rowing using the maize model developed in this paper allows for a more detailed observation of the mechanical seed rower seed rowing process, the finger clip structure and the specific processes of seed filling, seed cleaning and seed delivery and rowing of the nesting wheel, and the identification of seed fluency problems in the specific aspects of rowing, which can be targeted to improve the structure and enhance the rowing quality. Additions have been made to the concluding section of the paper in accordance with expert recommendations.

 

Author Response File: Author Response.docx

Reviewer 2 Report

The manuscript entitled “Modeling of typical shaped corn seeds and calibration of the coefficient of rolling friction” presents new results that can contribute in the area. The concept as well as the organizational layout of the article is, in my opinion, correctly prepared. The literature review integrates and interprets the existing results of the original research. The authors correctly designed the research experiment and selected the research methods. The authors correctly interpreted their own research results and conducted a substantive discussion of them in relation to previous research, and research by other authors. The article shows characteristics of originality and scientific novelty.

 

Some minor revisions:

In the abstract, the main information of the method used must be presented, as well as the main quantitative results of the study.

Keywords should not be repeated from title words.

I suggest that the authors report the results obtained with studies carried out with applications in the processes.

Jaques, L. B. A., Coradi, P. C., Rodrigues, H. E., Dubal, Í. T. P., Padia, C. L., Lima, R. E., & de Souza, G. A. C. (2022). Post-harvesting of soybean seeds–engineering, processes technologies, and seed quality: a review. International Agrophysics, 36(2), 59-81.

Jaques, L. B. A., Coradi, P. C., Lutz, É., Teodoro, P. E., Jaeger, D. V., & Teixeira, A. L. (2022). Nondestructive technology for real-time monitoring and prediction of soybean quality using Machine Learning for a bulk transport simulation. IEEE Sensors Journal.

 

The conclusions must be rewritten, in a timely manner, responding to each proposed objective.

Author Response

In the abstract, the main information of the method used must be presented, as well as the main quantitative results of the study.

Reply: I would like to thank the reviewers for their valuable comments and additions to the abstract for the use and results of the experiments.

 

Keywords should not be repeated from title words.

Reply: I would like to thank the reviewers for their valuable comments and The key words of the paper have been revised and reordered.

 

I suggest that the authors report the results obtained with studies carried out with applications in the processes.

 

Jaques, L. B. A., Coradi, P. C., Rodrigues, H. E., Dubal, Í. T. P., Padia, C. L., Lima, R. E., & de Souza, G. A. C. (2022). Post-harvesting of soybean seeds–engineering, processes technologies, and seed quality: a review. International Agrophysics, 36(2), 59-81.

 

Jaques, L. B. A., Coradi, P. C., Lutz, É., Teodoro, P. E., Jaeger, D. V., & Teixeira, A. L. (2022). Nondestructive technology for real-time monitoring and prediction of soybean quality using Machine Learning for a bulk transport simulation. IEEE Sensors Journal.

Reply: I would like to thank the reviewers for their valuable comments and references recommended by reviewers have been applied to the introduction of the paper.

 

The conclusions must be rewritten, in a timely manner, responding to each proposed objective.

Reply: I would like to thank the reviewers for their valuable comments and the conclusions have been revised.

 

Author Response File: Author Response.docx

Reviewer 3 Report

The authors have developed an interesting work to calibrate one mechanical parameter required to develop DEM models, that in addition it is quite difficult to be directly determined. However, the content of the manuscript should be significantly improved. Please, consider the following comments when preparing a revised version of the manuscript: 

1. Data included in Figures 4, 6 and 8 is not clearly presented since it seems that the sum of all frequencies is larger than 100%. Maybe, the problem would be related to the units of the axis, that has not been defined. Moreover, no legend has been provided for those figures. 

2. The content of section 2.1 is too large, and should be substantially shortened. It does not seem that the focus of the paper lies in this part, and only the minimum information to justify the particle type and the distribution of particles employed for the construction of DEM model should be needed. 

3. On the contrary, it is not clear how the authors obtained the figures included in section 2.3.2. They have not also included any legend to know which values are reported in figures. It is supposed that they have built a DEM model and varied the coefficient of rolling friction, thus obtaining different angles of repose. But it should be needed a comparison with experimental values in order to asses the required value of the coefficient of rolling friction. Authors should read a paper published recently in Agronomy, which is completely pertinent to this study, where this procedure is described (Madrid, M.; Fuentes, J.M.; Ayuga, F.; Gallego, E. 2022. Determination of the Angle of repose and coefficient of rolling friction for wood pellets. Agronomy 12 (2): 424). 

4. It seems that the authors have used several different methodologies to obtain the angle of repose for the material and later compared the experimental results with the theoretical DEM model. However, there should be a table showing a summary for comparison of all methods. 

5. The statistical analyses conducted have not been clearly described. In addition, it is of great importante to provide, at least, the standard deviation and coefficient of variance for all experimental and numerical tests conducted. A minimum of several repetitions (at least 5) should be conducted for all cases in order to check if there are not significant differences between both sets of results. This comparison should be made by conducting any hypothesis tests, e.g. t-Student. 

6. Once it is supposed that it has been determined the value of the coefficient of rolling friction, which has not been clearly stated, then it is supposed that it has been built a numerical model for the remaining experimental procedures tested (slump stacking, stacking experiment or metering seeds), but it has not defined clearly. 

 

 

I think that the quality of English is good, and no 

Author Response

The authors have developed an interesting work to calibrate one mechanical parameter required to develop DEM models, that in addition it is quite difficult to be directly determined. However, the content of the manuscript should be significantly improved. Please, consider the following comments when preparing a revised version of the manuscript:

 

1. Data included in Figures 4, 6 and 8 is not clearly presented since it seems that the sum of all frequencies is larger than 100%. Maybe, the problem would be related to the units of the axis, that has not been defined. Moreover, no legend has been provided for those figures.

Reply: Thanks to the reviewers for their valuable corrections, the total number of frequencies in the figure is greater than 100. Because of the small size differences, and the wider distribution of the distribution axes and the greater frequency of sizes, also to get a clearer view of the size distribution, the frequency of size occurrences is statistically plotted according to the actual frequency of size occurrence. Part 2.1 has been simplified in line with the second point suggested by the experts.

 

 

2. The content of section 2.1 is too large, and should be substantially shortened. It does not seem that the focus of the paper lies in this part, and only the minimum information to justify the particle type and the distribution of particles employed for the construction of DEM model should be needed.

Reply: Section 2.1.2 of Part 2.1 has been simplified in the light of expert comments. The figure has been specifically abridged and the information described in text only.

 

3. On the contrary, it is not clear how the authors obtained the figures included in section 2.3.2. They have not also included any legend to know which values are reported in figures. It is supposed that they have built a DEM model and varied the coefficient of rolling friction, thus obtaining different angles of repose. But it should be needed a comparison with experimental values in order to asses the required value of the coefficient of rolling friction. Authors should read a paper published recently in Agronomy, which is completely pertinent to this study, where this procedure is described (Madrid, M.; Fuentes, J.M.; Ayuga, F.; Gallego, E. 2022. Determination of the Angle of repose and coefficient of rolling friction for wood pellets. Agronomy 12 (2): 424).

 

Reply: Firstly, I would like to thank the experts for their valuable comments on the revisions. The model diagram for the simulated stacking has been supplemented in Figure 16 and is described in section 2.3.2. The method used in this paper reference is to fix the area of the slump of the repose angle to determine the height of the repose angle. to improve the accuracy of the determination. The traditional method of determining the stacking angle has a large error, so this paper uses the method of determining the height of the repose angle to achieve this. See below for references.

 

Chen, Z., et al., Determination of material and interaction properties of maize and wheat kernels for DEM simulation. Biosystems Engineering, 2020. 195: p. 208-226.

 

4. It seems that the authors have used several different methodologies to obtain the angle of repose for the material and later compared the experimental results with the theoretical DEM model. However, there should be a table showing a summary for comparison of all methods.

Reply: Thanks to the valuable modifications suggested by the experts, a comparison of the stacking angles formed by the two methods has been made in the supplementary table at the end of section 4.2.

 

 

5. The statistical analyses conducted have not been clearly described. In addition, it is of great importante to provide, at least, the standard deviation and coefficient of variance for all experimental and numerical tests conducted. A minimum of several repetitions (at least 5) should be conducted for all cases to check if there are not significant differences between both sets of results. This comparison should be made by conducting any hypothesis tests, e.g. t-Student.

Reply: Thanks to the valuable modifications suggested by the experts. The errors in the experiment results have been summarized in Table 7.

 

6. Once it is supposed that it has been determined the value of the coefficient of rolling friction, which has not been clearly stated, then it is supposed that it has been built a numerical model for the remaining experimental procedures tested (slump stacking, stacking experiment or metering seeds), but it has not defined clearly.

Reply: Thanks to the valuable modifications suggested by the experts. The calibrated coefficient of rolling friction has been described in the introductory section of section 4.

 

Author Response File: Author Response.docx

Reviewer 4 Report

1. As a prospect for further expansion of the research results, I consider it expedient to carry out research on the orientation of corn grains when fed by a planter into the furrow (and to carry out research on the effect of the position of the corn grain in the furrow on the yield).

2. I consider it expedient to present the values of the rolling and sliding friction coefficients of various forms of corn seeds.

3. It is necessary to provide instrumentation for research, as well as theoretical prerequisites for the development of the installation shown in Figure 27, as well as indicators of the quality of sowing corn seeds.

Author Response

1. As a prospect for further expansion of the research results, I consider it expedient to carry out research on the orientation of corn grains when fed by a planter into the furrow (and to carry out research on the effect of the position of the corn grain in the furrow on the yield).

Reply: I would like to thank the reviewers for their valuable suggestions. The expansion of the research results of this paper will be studied from the whole link of the seeder and the process of seed arranging, the direction of seed drop has an impact on the seedling rate and seedling flush.

 

2. I consider it expedient to present the values of the rolling and sliding friction coefficients of various forms of corn seeds.

Reply: Thank you very much for your approval and I will continue to study the results in depth for application in seeders.

 

3. It is necessary to provide instrumentation for research, as well as theoretical prerequisites for the development of the installation shown in Figure 27, as well as indicators of the quality of sowing corn seeds.

Reply：Thanks to the valuable suggestions made by the reviewers, additional explanations have been provided for the seeding unit in Figure 17, as well as for the performance indicators of the unit for seeding.

 

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Ok I agree to puplish the paper

Author Response

Thanks to the valuable comments from the experts。

 

Reviewer 2 Report

The manuscript had significant improvements. With the revisions done, it can be accepted.

Author Response

Thanks to the valuable comments from the experts.

 

Reviewer 3 Report

The authors have improved the paper considering most of the comments made by the reviewer. However, some aspects are still confusing and should be corrected: 

1. If the authors have devoted a significant part of the research to calibrate the calculation of coefficient of rolling friction, then why they use a value provided in a reference for developing the numerical models used for "slump stacking experiment" and "stacking experiment"? This does not have any rigor. 

2. As it was previously indicated in the previous research (and again in one of the following comments), no clear explanation about the statistical analyses conducted in this research has been added to the manuscript. 

3. Table 7. The authors should clarify it the value accompanying to the mean is the standard deviation or the coefficient of variation. 

4. Tables 1 and 3. When a linear regression analysis is conducted, the goodness of fit of the proposed equation is measured trough the square coefficient of correlation (R²) or simply the coefficient of correlation (R). Thus, it is meaningless to refer to "standard deviation" in this sense. I do not know if the term "standard deviation" is a mistake, and it should read "Coefficient of correlation". Please, clarify this aspect and provide the actual value of R or R² obtained for the equations proposed. R² > 0.7 usually means that a significant relation exists, and a great part of the data variability is explained by the model. However, to prove that the proposed equation really predicts the expected value, then a F-test or t-Test should be conducted to check the p-value obtained. Therefore, the authors should clearly explained what type of statistical analyses have been conducted. 

No significant changes in English language are required. 

Author Response

1. If the authors have devoted a significant part of the research to calibrate the calculation of coefficient of rolling friction, then why they use a value provided in a reference for developing the numerical models used for "slump stacking experiment" and "stacking experiment"? This does not have any rigor.

Reply: To verify the simulation reliability of the simplified maize model and the calibrated coefficient of rolling friction, two different types of stacking angle formation methods were used to verify the predictability of the maize model and to further verify that the maize model developed in this paper. This further verifies that the maize model developed has some predictive accuracy in the seed metering process. Moreover, under the condition of certain gravitational potential energy of maize, the coefficient of rolling friction is ultimately and uniquely determined after determining the of rolling friction in advance. Based on this, the method to calibrate the coefficient rolling friction is to find the different coefficient of rolling friction of maize seeds more accurately with different shapes, further enhancing the predictiveness of the simulated maize model.

 

2. As it was previously indicated in the previous research (and again in one of the following comments), no clear explanation about the statistical analyses conducted in this research has been added to the manuscript.

Reply: The number of experiment statistics and the method of taking the results have been added to the description of several experiments in the paper.

 

 

3. Table 7. The authors should clarify it the value accompanying to the mean is the standard deviation or the coefficient of variation.

Reply: Thanks to the reviewer for raising the issue, I have amended the issue in Figure 7, specifically the standard deviation.

 

4. Tables 1 and 3. When a linear regression analysis is conducted, the goodness of fit of the proposed equation is measured trough the square coefficient of correlation (R2) or simply the coefficient of correlation (R). Thus, it is meaningless to refer to "standard deviation" in this sense. I do not know if the term "standard deviation" is a mistake, and it should read "Coefficient of correlation". Please, clarify this aspect and provide the actual value of R or R2 obtained for the equations proposed. R2 > 0.7 usually means that a significant relation exists, and a great part of the data variability is explained by the model. However, to prove that the proposed equation really predicts the expected value, then a F-test or t-Test should be conducted to check the p-value obtained. Therefore, the authors should clearly explain what type of statistical analyses have been conducted.

Reply: Thanks to the valuable comments from the experts, several dimensional linear fit relationships have been modified to better fit R², with some dimensions fitting better than 0.7 to each other and some dimensions fitting worse. This paper mainly uses these simple relationships of dimensions to build a simplified model of maize, there are some differences between the simplified model and the actual maize dimensions. Therefore, no further dimensional difference tests were conducted here.