## 3 Results
### Characteristics of the Network Structure of UAs in the Context of COVID-19  
The overall network structure characteristics in the context of COVID-19 are calculated through the Ucinet 6.0 software, including network connectivity and network hierarchy.  
Based on the results obtained from Table 1 and Figure 4, the following insights can be drawn regarding the characteristics of China's UA network structures under the influence of COVID-19:  
Numerically, the connectivity and hierarchy of China's UA network structures display a common trend of initial decline followed by recovery during COVID-19's influence. Moreover, varying degrees of impact and recovery are observed among different UAs. Overall, these UAs exhibit three hierarchical levels of network structure characteristics that correspond to their developmental stages. UAs with a high level of development displayed notably higher network connectivity and hierarchy than those in the growth stage of development and in the primary stage of development.  
Regarding the development types of UAs, the UAs with a high level of development are severely affected in terms of network connectivity and hierarchy during COVID-19. This decline is correlated with the level of development, signifying that more mature UAs suffered a greater impact from COVID-19. However, these UAs rapidly recovered their network structures after COVID-19, indicating their relatively strong network stability. They could respond quickly and undergo reconstruction after being affected by public health emergencies.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**UA**} & \multicolumn{2}{c}{**Before COVID-19**} & \multicolumn{2}{c}{
\begin{tabular}{c} **The Normalization Stage** \\ **of COVID-19** \\ \end{tabular} } & \multicolumn{2}{c}{**After COVID-19**} \\ \cline{2-7}  & **Connectivity** & **Hierarchy** & **Connectivity** & **Hierarchy** & **Connectivity** & **Hierarchy** \\ \hline  & 10,003 & 0.853 & 8524 & 0.794 & 9963 & 0.814 \\  & 6447 & 0.838 & 4563 & 0.581 & 6796 & 0.797 \\  & 8845 & 0.837 & 7305 & 0.609 & 8655 & 0.785 \\  & 618  
In the UAs in the growth stage of development, the influence on network connectivity and hierarchy tends to be comparatively subdued. The network structures of these UAs displayed an inherent immaturity before COVID-19, marked by a generally feeble connectivity and hierarchy. Consequently, the impact during COVID-19 was less pronounced. Nonetheless, these UAs demonstrated a relatively inadequate recovery of network structure stability after COVID-19, underscoring the imperative for heightened stability and reinforced connections across various dimensions. This indicates an ongoing journey towards achieving a mature level of network structure.  
UAs in the primary stage of development displayed low network structure stability before COVID-19, with a relatively minor impact during COVID-19. These UAs exhibited significant post-pandemic recovery and exceeded pre-pandemic levels, indicating their rapid development and progress.  
In summary, the evolution pattern of network structure in China's UAs can be broadly summarized as a two-stage process: disruption due to COVID-19 followed by recovery  
Figure 4: Results for network indicators for various UAs at different time periods under the impact of COVID-19.  
and reconstruction. The COVID-19 pandemic had a considerable impact on UA network structures, with varying degrees of influence observed across different UAs, leading to noticeable spatial differences. Further in-depth research is needed to explore the factors affecting the UA network structures during COVID-19.