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'''A multi-objective green UAV routing problem'''

Coelho, Bruno N.; Coelho, Vitor N.; Coelho, Igor M.; Ochi, Luiz S.  ; Haghnazar K., Roozbeh; Zuidema, Demetrius;. Lima, Milton S.F; da Costa, Adilson R., "A multi-objective green UAV routing problem", Elsevier, (December, 2017) https://www.sciencedirect.com/science/article/pii/S0305054817301028?via%3Dihub 

===Summary===
The development of UAV’s started in the military. From there on, the technology spread to many other sectors that also benefit from it for performing various tasks. Nowadays, the biggest problems for the development of delivery drones are the very strict rules for drones (no flying in urban environments, drone must stay in sight of pilot, etc.) and the limited battery life of a drone. This paper considers a Green UAV Routing Problem (GUAVRP), which minimizes seven objective functions: total traveled distance; UAV’s maximum speed; number of used vehicles; makespans of the last collected and delivered package; average time spent with each package; and maximize batteries load at the end of the schedule. For the model, it is assumed that there are two flight levels: one low level for smaller drones and a higher level for bigger ones. In the map, there are also several refueling stations. According to the article ‘’The main contributions of this current work are:

Develop a mathematical programming model for a time- dependent UAV heterogeneous fleet routing problem, in particular:
respecting UAVs operational requirements;
tackling the micro-airspace considering a multi-layer scenario with package exchanging points;
integrating UAVs into the new concepts of mini/microgrid systems, in which vehicles can be charged at different points of the future smart cities.
Consider a multi-objective optimization framework in order to provide alternative solutions with different possible routes and schedules.’’
There are no real conclusions in this paper, it is mostly about making the model itself.