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Edge computing offloads the data processing capacity to the user side, provides flexible and efficient computing services for the development of smart city, and brings many security challenges. Aiming at the problems of fuzzy boundary security protection and dynamic identity authentication in the edge computing environment in smart city, the zero trust architecture based on blockchain is studied, and a digital identity model and dynamic authentication scheme of edge computing nodes based on distributed ledger are proposed. Firstly, a digital identity model of two-way authentication between edge computing node and sensing terminal is established to realize fine-grained authorization and access control in edge computing. Secondly, based on the identity data and behavior log bookkeeping on the chain, the quantification of trust value, trust transmission and update are realized, and the traceability of security events is improved. Finally, based on the improved RAFT consensus algorithm, the multi-party consensus and consistency accounting in the authentication process are realized. Simulation results show that this scheme can meet the requirements of zero trust verification in edge computing environment, and has good efficiency and robustness.

The fine particulate matter (PM 2.5 ) emitted by burning biomass has become the main source of pollution in cities; this pollution seriously threatens the ecosystem and inhabitants' health. A major challenge in dealing with this issue is the uncertainty regarding the influence of burning biomass on PM 2.5 regional transport. In this study, Harbin-Changchun Megalopolis is the research area. Using the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model combined with satellite data and PM 2.5 monitoring data, we quantitatively analyzed the regional transport of PM 2.5 from burning biomass upwind of each city under different emission conditions. Conditions at burn sites, especially emission intensity and meteorological factors, as well as transport distance play significant roles in the regional transport of PM 2.5 . Higher emission intensity aggravated the concentration of downwind PM 2.5 , at most 19.7 μg ⋅ m -3 . Shorter transport distance strengthened the impact of biomass burning on downstream PM 2.5 by weakening elimination, which could be up to 96.8 μg ⋅ m -3 . Moreover, meteorological factors at fire points were closely related to the transport of PM 2.5 . First, lower planetary boundary layer height could enhance the transport of PM 2.5 from the burning biomass by inhibiting vertical diffusion, and the enhancement could be up to 46.1 μg ⋅ m -3 . Second, compared to strong wind, light wind caused the weaker dilution, enhancing PM 2.5 regional transport by as much as 32.5 μg ⋅ m -3 . Third, relatively humidity at 30%-40% had the strongest effect in facilitating the transport of PM 2.5 from burning biomass. We conclude that comprehensively considering these three factors, namely the emission intensity, transport distance and meteorological factors at burn sites can facilitate the cross-regional development of accurate prediction models and effective pollution control measures., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)