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Active fault is a major risk source of urban earthquake disaster. Accurately identifying the spatial geometry distribution features of active fault is the basis for urban seismic risk migration. However, due to the large-scale and deep urban renewal by human activities and urbanization, the traces of active faults are obscure and invisible on the surface, which makes it hard to identify the surface geometry of this kind of active faults. Though the northern Shuiyu fault in the central part of the Datong Basin is bounded by the eastern edge of the Mapu Mountain and characterized by linear displaced landforms, the southern section of the Shuiyu fault crossing the Yudong District of Datong City is covered by dense buildings and roads, becoming an "invisible" fault. In this study, based on the 1965 historical aerial photos of the Datong region in the 1960's and the 1∶10000 topographic maps, we reconstructed the original DEM and DOM of this region using the aerial photo stereopair and stereoscopic photography. These original data revealed the geometry distribution characteristics of the Shuiyu fault. Our results show that the piedmont fault scarps are marked by prominent linear features along the northern Shuiyu fault. We can accurately locate the fault by the images. Based on the previous Keyhole satellite images, DOM and DEM data, the geometric distribution of the fault in the southern Shuiyu fault can be accurately determined. Topographic profiles extracted from the original DEM show that the vertical offset on terrace T3 along the Shuiyu fault is about 19 meters. On this basis, the fault natural exposures and shallow seismic reflection data demonstrate that it is feasible to accurately locate the "invisible" active fault in the city by using historical aerial photos and stereoscopic photography. This study provides not only an important basis for the seismic hazard assessment in the Datong region but a useful technique for the detection of "invisible" active faults beneath a city.

To investigate the self-healing performance of multi-walled carbon nanotube-modified asphalt and its influencing mechanism, the asphalt molecular self-healing models were established by the molecular dynamics method. The results were analyzed based on molecular diffusion theory and surface energy repair theory. Based on the Arrhenius model, two theories were combined, and a new index healing factor was proposed to evaluate the self-healing performance by considering the diffusion characteristics and energy changes of asphalt molecules. The results show that multi-walled carbon nanotubes can accelerate the diffusion behavior of molecules in the temperature of 278--318 K to improve the self-healing properties of asphalt. Based on the proposed surface free energy equation, the self-healing properties are reasonably evaluated; the enthalpy change can be used as an index for judging the self-healing performance. The transformation model of the diffusion coefficient and cohesive work and the new index can reflect the self-healing performance more comprehensively. [ABSTRACT FROM AUTHOR]

A novel malware propagation model is suggested in this paper. Contrary to existing models for malware spreading under the deployed honeynet, honeypots in our model can be dynamically deployed according to the overall infection size within the network. The basic reproduction number that determines the persistence of malware is derived, and the existence and uniqueness of the malware equilibrium are investigated. Using the basic reproduction number, we proved that the malware-free equilibrium is locally and globally asymptotically stable. Numerical simulations are performed to illustrate the theoretical results, showing that nodes with higher degree values are conducive to the spread of malware, and network with a small power law index has a higher spreading level. Furthermore, the total number of needed honeypots is governed by both infection size and network topology. Based on the results, some ideas for the effective design of a honeynet are suggested.