## 4 Simulation and Analysis
### Results of Analysis
This result proves the effectiveness of using MMAS to solve the lower-layer model, and a public air-route planning scheme with a lower cost is obtained using MMAS under the same location-selection results. According to the analysis of each air route, nine of the 17 routes had a negative optimization of the route's air range, of which eight routes had a negative optimization rate of less than 5% and one route had a negative optimization rate of 10-15%. In addition, there are four air-range-optimization routes among the 13 transit routes. Analyzing the results, the planned route of the A* algorithm is not the optimal solution, and the route-smoothing method used in this paper cannot ensure that the route can be smoothed into the optimal configuration, which further increases the uncertainty of the route cost. Therefore, some transit routes composed of multiple edges may have slightly  
Figure 11: Logistics UAV parcel-receiving stations and public air-route planning result. (**a**) Parcel-receiving station location results and demand-point-matching relationship. (**b**) Public air-route planning results based on MMAS. \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & **Direct Air Route** & **Public Air Route** & **Optimization Rate** & **Passing Station** \\ \hline \hline  & route1 & 93.72 & 93.72 & 0.00\% & 1 \\  & route2 & 111.38 & 124.47 & \(-11.75\%\) & \(5,4,2\) \\  & route3 & 115.45 & 117.21 & \(-1.52\%\) & \(5,4,3\) \\  & route4 & 79.20 & 79.19 & 0.01\% & \(5,4\) \\  & route5 & 56.83 & 56.83 & 0.00\% & \(5\) \\  & route6 & 35.69 & 35.69 & 0.00\% & \(6\) \\  & route7 & 26.91 & 26.91 & 0.00\% & \(7\) \\  & route8 & 85.25 & 84.18 & 1.25\% & \(7,8\) \\ air-range cost & route9 & 74.78 & 76.62 & \(-2.46\%\) & \(7,9\) \\  & route10 & 149.81 & 148.57 & 0.83\% & \(6,10\) \\  & route11 & 142.84 & 143.48 & \(-0.45\%\) & \(6,11\) \\  & route12 & 179.98 & 181.10 & \(-0.62\%\) & \(6,11,12\) \\  & route13 & 206.26 & 205.17 & 0.52\% & \(6,10,13\) \\  & route14 & 150.09 & 153.15 & \(-2.04\%\) & \(6,14\) \\  & route15 & 186.52 & 189.09 & \(-1.38\%\) & \(6,14,15\) \\  & route16 & 162.75 & 167.90 & \(-3.16\%\) & \(7,16\) \\  & route17 & 194.10 & 200.04 & \(-3.06\%\) & \(7,16,17\) \\ \hline \hline  & collision risk & 4.40 & 2.82 & 35.81\% & \\ \hline  & crash risk & 487.92 & 263.73 & 45.95\% & \\ \hline  & noise risk & 112.08 & 76.16 & 32.05\% & \\ \hline  & total risk & 604.40 & 342.72 & 43.30\% & \\ \hline  & total cost & 2558.40 & 2426.04 & 5.17\% & \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Public air-route planning results. better planning results than direct routes, which is caused by the limitations of A* algorithm and the smoothing method used in this paper. The optimization degree of the four distance-optimization routes is not high, namely, 0.01%, 0.52%, 0.83%, and 1.25%, respectively. This also proves that although the single-air-route planning method proposed in this paper has some volatility, its overall results are excellent. Otherwise, compared with the public air route combined with the direct route for all stations in Figure 12, the route configuration in Figure 11 is simpler, the number of intersections is less, and it is easier to supervise the UAV operation. The actual layout of round-trip public air routes is shown in Figure 13. In the figure, the blue route is the public route for delivery, the red route is the public route for returning, and the blue column is the vertical takeoff and landing procedure of the UAV at the distribution warehouse and parcel-receiving station. In actual operation, the logistics UAV starts from the distribution warehouse, climbs to the height of the delivery route according to the established vertical takeoff and landing procedure, uses the delivery route to transport the logistics parcels to the parcel-receiving station, places the parcels according to the takeoff and landing procedure, climbs to the height of the return route, and returns to the distribution warehouse using the return route with an empty aircraft.