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With the increasing number of airports and the expansion of their scale, the aviation network has become complex and hierarchical. In order to investigate the complex network characteristics of aviation networks, this paper constructs a Chinese aviation network model and carries out related research based on complex network theory and K-means algorithm. Initially, the P-space model is employed to construct the Chinese aviation network model. Then, complex network indicators such as degree, clustering coefficient, average path length, betweenness and coreness are selected to investigate the complex characteristics and hierarchical features of aviation networks and explore their causes. Secondly, using K-means clustering algorithm, five values are obtained as the initial clustering parameter K values for each of the aviation network hierarchies classified according to five complex network indicators. Meanwhile, clustering simulation experiments are conducted to obtain the visual clustering results of Chinese aviation network nodes under different K values, as well as silhouette coefficients for evaluating the clustering effect of each indicator in order to obtain the hierarchical classification of aviation networks under different indicators. Finally, the silhouette coefficient is optimal when the K value is 4. Thus, the clustering results of the four layers of the aviation network can be obtained. According to the experimental results, the complex network association discovery method combined with K-means algorithm has better applicability and simplicity, while the accuracy is improved. [ABSTRACT FROM AUTHOR]

To enhance the accuracy of performance analysis of regional airline network, this study applies complex network theory and Density-Based Spatial Clustering of Applications with Noise (DBSCAN) algorithm to investigate the topology of regional airline network, constructs node importance index system, and clusters 161 airport nodes of regional airline network. Besides, entropy power method and approximating ideal solution method (TOPSIS) is applied to comprehensively evaluate the importance of airport nodes and complete the classification of nodes and identification of key points; adopt network efficiency, maximum connectivity subgraph and network connectivity as vulnerability measurement indexes, and observe the changes of vulnerability indexes of key nodes under deliberate attacks and 137 nodes under random attacks. The results demonstrate that the decreasing trend of the maximum connectivity subgraph indicator is slower and the decreasing trend of the network efficiency and connectivity indicators is faster when the critical nodes of the regional airline network are deliberately attacked. Besides, the decreasing trend of the network efficiency indicator is faster and the decreasing trend of the maximum connectivity subgraph indicator is slower when the nodes of four different categories are randomly attacked. Finally, it is proposed to identify and focus on protecting critical nodes in order to better improve the security level of regional airline system. [ABSTRACT FROM AUTHOR]

PoW (Proof of Work) plays a significant role in most blockchain systems to grant an accounting right over decentralized participants and ensure tamper resistance. Though hash functions are generally exploited for PoW due to their merits on summering, anti-collision, and irreversibility, they cannot certify that the bookkeeper is exactly the worker. Thereafter, such insistence may lead to abuse or even embezzlement of computing power for the benefit of malicious miners. To preserve the functionality of PoW but also bind the miners' signing keys with their works, we build a post-quantum PoW scheme by changing the approximate closest vector norm for probabilistic NTRUSign. Different from the schemes based on hash functions, our scheme takes signing as the proof of work where signature verification is just the evidence of block reward. We also presented a method to adjust the difficulty of signing by modifying the probability of generating a correct signature. The performance of our scheme is also analyzed theoretically and experimentally, which implies its practicability and advantages. [ABSTRACT FROM AUTHOR]