In order to solve the problem of insufficient mining of potential association between remote nodes in human action recognition tasks, and the problem of high training cost caused by using multi-modal data, a multi-scale feature fusion human action recognition method under the condition of single mode was proposed. Firstly, the global feature correlation of the original skeleton diagram of human body was carried out, and the coarse-scale global features were used to capture the connections between the remote nodes. Secondly, the global feature correlation graph was divided locally to obtain the Complementary Subgraphs with Global Features (CSGFs), the fine-scale features were used to establish the strong correlation, and the multi-scale feature complementarity was formed. Finally, the CSGFs were input into the spatial-temporal Graph Convolutional module for feature extraction, and the extracted results were aggregated to output the final classification results. Experimental results show that the accuracy of the proposed method on the authoritative action recognition dataset NTU RGB+D60 is 89.0% (X-sub) and 94.2% (X-view) respectively. On the challenging large-scale dataset NTU RGB+D120, the accuracy of the proposed method is 83.3% (X-sub) and 85.0% (X-setup) respectively, which is 1.4 and 0.9 percentage points higher than that of the ST-TR (Spatial-Temporal TRansformer) under single modal respectively, and 4.1 and 3.5 percentage points higher than that of the lightweight SGN (Semantics-Guided Network). It can be seen that the proposed method can fully exploit the synergistic complementarity of multi-scale features, and effectively improve the recognition accuracy and training efficiency of the model under the condition of single modal.
To deal with the phenomenon of "information and value islands" caused by the lack of interoperation among the increasingly emerging blockchain systems, a federated?autonomy?based cross?chain scheme was proposed. The elemental idea of this scheme is to form a relay alliance chain maintained by participated blockchain systems using blockchain philosophy, which is supposed to solve the data sharing, value circulation and business collaboration problems among different blockchain systems. Firstly, a relay mode based cross?chain structure was proposed to provide interoperation services for heterogeneous blockchain systems. Secondly, the detailed design of the relay alliance chain was presented as well as the rules for the participated blockchain systems and their users. Then, the basic types of cross?chain interactions were summarized, and a process for implementing cross?chain interoperability based on smart contracts were designed. Finally, through multiple experiments, the feasibility of the cross?chain scheme was validated, the performance of the cross?chain system was evaluated, and the security of the whole cross?chain network was analyzed. Simulation results and security analysis prove that the proposed channel allocation strategy and block?out right allocation scheme of the proposed scheme are practically feasible, the throughput of the proposed shceme can reach up to 758 TPS (Transactions Per Second) when asset transactions are involved, and up to 960 TPS when asset transactions are not involved; the proposed scheme has high?level security and coarse? and fine?grained privacy protection mechanism. The proposed federated?autonomy?based cross?chain scheme for blockchain can provide secure and efficient cross?chain services, which is suitable for most of the current cross?chain scenarios.