## 6 Example Solution and Analysis
### Sensitivity Analysis
#### 6.3.2 Effectiveness of Comprehensive Cost Reduction  
In our numerical experiments, the specific parameters were kept constant. To demonstrate the effectiveness at reducing carbon emissions and logistics cost, we introduced the traditional distribution method as a control group. The comparison between the five distribution methods is shown below in Table 9. The comparison chart of the five approaches in Example 1 is shown in Figure 11.  
Figure 10: A comparison chart of computational time for four optimization algorithms. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Number of Nodes** & **LNS** & **AGO** & **GWO** & **IGWO** \\ \hline
80 & 0.01 & 0.07 & 0.22 & 0.00 \\
120 & 0.00 & 0.10 & 0.52 & 0.00 \\
160 & 0.04 & 0.13 & 1.17 & 0.00 \\
200 & 0.01 & 0.09 & 2.59 & 0.00 \\
240 & 0.12 & 0.70 & 3.93 & 0.00 \\
280 & 1.33 & 2.54 & 4.59 & 0.00 \\
320 & 2.02 & 2.97 & 4.99 & 0.00 \\
360 & 2.84 & 3.66 & 5.76 & 0.00 \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Comparison table of four algorithms. Given the results in Table 7, it is obvious that our proposed method in this paper has a significant improvement in the context of comprehensive cost and carbon emissions. Compared with the traditional drug cold chain logistics model, grey wolf algorithm,  
Figure 11: Comparison chart of five algorithms for Example 1. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Region** & **Transportation** & **IGWO** & **Traditional Distribution** & & & & \\
**Consumption** & **IGWO** & **Method** & **GWO** & **AG** & **LNS** \\ \hline \multirow{4}{*}{1} & Delivery method & Vans & Refrigerated trucks & Refrigerated & Refrigerated & Refrigerated \\  & Logistics cost/RMB & 3443.01 & 3720.26 & 3729.60 & 4977.64 & 5401.46 \\  & Carbon emissions/t & 0.574 & 1.34 & 1.375 & 1.835 & 1.991 \\ \hline \multirow{4}{*}{2} & Delivery method & Vans & Refrigerated trucks & Vans & Vans & Vans \\  & Logistics cost/RMB & 3190.29 & 3783.01 & 1483.01 & 2169.12 & 2252.396 \\  & Carbon emissions/t & 0.584 & 1.362 & 0.439 & 0.439 & 0.480 \\ \hline \multirow{4}{*}{3} & Delivery method & Refrigerated trucks & Refrigerated trucks & Vans & Vans & Vans \\  & Logistics cost/RMB & 3011.86 & 3011.86 & 3059.15 & 2625.17 & 2603.64 \\  & Carbon emissions/t & 1.11 & 1.11 & 0.494 & 0.575 & 0.565 \\ \hline \multirow{4}{*}{4} & Delivery method & Refrigerated trucks & Refrigerated trucks & Vans & Vans & Vans \\  & Logistics cost/RMB & 2735.10 & 2735.10 & 4062.44 & 3759.59 & 2768.95 \\  & Carbon emissions/t & 1.008 & 1.008 & 0.749 & 0.781 & 0.575 \\ \hline \multirow{4}{*}{5} & Delivery method & Refrigerated trucks & Refrigerated trucks & Refrigerated & Refrigerated & Refrigerated \\  & Logistics cost/RMB & 2960.33 & 2960.33 & 2869.19 & 3331.25 & 2969.35 \\  & Carbon emissions/t & 1.091 & 1.091 & 1.058 & 1.228 & 1.094 \\ \hline \multirow{4}{*}{6} & Delivery method & Vans & Refrigerated trucks & Refrigerated & Refrigerated & Refrigerated \\  & Logistics cost/RMB & 2797.20 & 3035.86 & 3983.98 & 2946.48 & 4181.09 \\  & Carbon emissions/t & 0.480 & 1.119 & 1.468 & 1.086 & 1.541 \\ \hline \multirow{4}{*}{7} & Delivery method & Vans & Refrigerated trucks & Vans & Refrigerated & Refrigerated \\  & Logistics cost/RMB & 3815.46 & 4514.45 & 3647.303 & 3762.25 & 3714.27 \\  & Carbon emissions/t & 0.714 & 1.507 & 0.703 & 1.387 & 1.369 \\ \hline \multirow{4}{*}{Total} & Logistics cost/RMB & 21,923.26 & 23,760.87 & 22,834.67 & 23,571.49 & 23,891.17 \\  & Carbon emissions/t & 5.561 & 8.599 & 6.871 & 7.331 & 7.615 \\ \hline \hline \end{tabular}
\end{table} 
Table 9: Comparison table of cost and carbon emissions of five methods. ant colony algorithm, and large neighborhood search algorithm, the comprehensive cost decreased by 7.73%, 3.99%, 6.99%, and 8.24%, respectively, and the carbon emissions decreased by 35.33%, 19.07%, 24.14%, and 26.97%, respectively. Moreover, in order to figure out to what extent this optimization improves the dual distribution scheme in each season, we took the refrigerant-related costs into consideration.