Online Delivery Problem for Hybrid Truck–Drone System with Independent and Truck-Carried Drones

Round 1

Reviewer 1 Report

The online delivery problem of hybrid truck-drone collaboration system studied in the manuscript is interesting. However, it cannot be published in the current form due to the flaws listed as follows.

 

1.       It is better to explain the importance and the existing problem of the research topic in the introduction section. In addition, the delivery problem of hybrid truck-drone system can be regarded as an application case of the VRPs. I suggest authors add a separate literature review of the most relevant research of VRPs and mention the wild applications of methodologies of VRPs such as berth allocation, machine scheduling in the following literatures.

Wang Z, Sheu J B. Vehicle routing problem with drones. Transportation research part B: methodological, 2019, 122: 350-364.

Tang, M., Ji, B., Fang, X., Yu, S. S. Discretization-Strategy-Based Solution for Berth Allocation and Quay Crane Assignment Problem. Journal of Marine Science and Engineering, 2022, 10(4), 495.

Fanjul-Peyro L, Ruiz R, Perea F. Reformulations and an exact algorithm for unrelated parallel machine scheduling problems with setup times. Computers & Operations Research, 2019, 101: 173-182.

2.       It is noted that the English grammar and sentence structure of this manuscript needs to be further improved.

3.       To better understand the problem you are studying, please describe fig.1(c) as the way you illustrating fig.1(a) and fig.1(b).

4.       Too much space left on the right side of Table 1 and Table 5.

5.       The payload of drones is 1 which means the drone can only delivery cargoes with a weight of 1 each time. Does this mean that the demand at each request is 1, or the request can be split?

6.       The author defines dij as the distance between point i and point j, i, j ∈ R′ which includes the distance between point j and origin. What is the difference between d0j and d(0, ri) ?

7.       Please define parameters and variables separately in table 2. Why not advance the definition of Td, Tfs, T and Copt(r)? They are not variables.

8.       Add the definition of ui to Table 2. Please ensure that all parameters and variables are defined in the Table 2.

9.       There are only 2 drones in your problem. Is there any literature supporting this? Is it more reasonable to set the number of drones as a parameter and set the specific number of drones in the numerical experiments?

10.   I suggest better outline the novelty of the proposed solution method with respect to the classical online algorithm

11.   The algorithm needs more detailed description. A flowchart or pseudocode can help understanding the online algorithm.

12.   The structure of this paper is illogical, I suggest adjust the order of each section. Introduce your model formulation in section 3. Introduce the online algorithm before you prove its lower bound. Separate the description of the algorithms and simulation analysis.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

I propose some suggestions in order to improve the proposed study:

 

1-      The form of the paper should be revised by adding a conclusion summarizing the originality of the study and the obtained results. The authors propose a section 8 discussion, but I think a conclusion is compulsory  

2-      No real prospects according the proposed is disused; The authors should add and argument some real prospects     

3-      The authors don’t take into account the reliability of the drones. I Think by adding the constraint of the reliability of the drones the problem will be more interest. If it is not complex to take into account this constraint in the model and search a new result, it is recommended until the authors should precise the point of the drone reliability in assumptions

4-      Some studies according to delivery drone dealing with similar problem and taking into account the reliability and the drone battery recharge can be added in the bibliography study and discussed according the propose study. I give an example of study

“A. Troudi, SA.Addouche, S. Dellagi, A. Mhammedi, (2018)  “Sizing of the Drone Delivery Fleet Considering Energy Autonomy”. Sustainability, Volume 10, issue 9, September 2018, doi: 10.3390/su10093344 “

 

5-      It is clear the solving of the proposed problem is complex, but the authors should add a sensitivity study according some principal date in order to prove the robustness of the mathematical model developed

6-      The economic gain according the proposed delivery strategy based on truck-carried drones is not justified! Is it possible to consider the traditional delivery strategy and prove or estimate the economic gain?

7-      The proofs of lemma (1 and 2) should be more detailed! It is presented briefly

8-      In the table 1 the authors assume that the payload of the truck is infinite, I think that’s a big assumption. In the case of more one drone, this assumption has to be justified   

 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf