Application of TSD tunnel seismic prediction system in karst area

TSD is one of the classical methods of tunnel seismic prediction based on higher accuracy multi-wave multi-component seismology.The working principle of the TSD and an application example of the TSD on tunnel prediction in Chongqing are introduced in this paper.This system has two ports for speed signal and acceleration signal,and the equipment is more portable and easy to use.According to the application results we can conclude that the TSD prediction system is accurate and it has the wide application prospect in tunnel seismic detection.

Application of ultrasonic CT method in nondestructive detection of interior defects in large scale concrete structural member of bridge

The ultrasonic computed tomography （USCT） method is derived from the basic principles of X-ray section scanning. This method records the arriving times of ultrasonic wave between the probes and the sources to ealculate the elastic wave velocity values in the section using the arrival times. Through analyzed the distribution Of elastic wave velocity in aim area, the information of the strength and the homogeneity of the investigated zone could be got indirectly. The authors introduced the operational principle of USCT and a practical case of using this method to detect the interior defects in large scale concrete structural member. Compared with other exploration methods, this method is more efficient and accurate.

Boosted charge transfer and photocatalytic CO_(2) reduction over sulfurdoped C_(3)N_(4) porous nanosheets with embedded SnS_(2)-SnO_(2) nanojunctions

Two-dimensional porous nanosheet heterostructure materials,which combine the advantages of both architecture and components,are expected to feature a significant photocatalytic performance toward CO_(2) conversion into useful fuels.Herein,we provide a facile strategy for fabricating sulfur-doped C_(3)N_(4) porous nanosheets with embedded SnO_(2)-SnS_(2) nanojunctions(S-C_(3)N_(4)/SnO_(2)-SnS_(2))via liquid impregnation-pyrolysis and subsequent sulfidation treatment using a layered supramolecular structure as the precursor of C_(3)N_(4).A hexagonal layered supramolecular structure was first prepared as the precursor of C_(3)N_(4).Then Sn^(4+) ions were intercalated into the supramolecular interlayers through the liquid impregnation method.The subsequent annealing treatment in air simultaneously realized the fabrication and efficient exfoliation of layered C_(3)N_(4) porous nanosheets.Moreover,SnO_(2) nanoparticles were formed and embedded in situ in the porous C_(3)N_(4) nanosheets.In the following sulfidation process under a nitrogen atmosphere,sulfur powder can react with SnO_(2) nanoparticles to form SnO_(2)-SnS_(2) nanojunctions.As expected,the exfoliation of sulfur-doped C_(3)N_(4) porous nanosheets and ternary heterostructure construction could be simultaneously achieved in this work.Sulfur-doped C_(3)N_(4) porous nanosheets with embedded SnO_(2)-SnS_(2) nanojunctions featured abundant active sites,enhanced visible light absorption,and efficient interfacial charge transfer.As expected,the optimized S-C_(3)N_(4)/SnO_(2)-SnS_(2) achieved a much higher gas-phase photocatalytic CO_(2) reduction performance with high yields of CO(21.68μmol g^(−1)h^(−1))and CH_(4)(22.09μmol g^(−1)h^(−1))compared with the control C_(3)N_(4),C_(3)N_(4)/SnO_(2),and S-C_(3)N_(4)/SnS_(2) photocatalysts.The selectivity of CH_(4) reached 80.30%.Such a promising synthetic strategy can be expected to inspire the design of other robust C_(3)N_(4)-based porous nanosheet heterostructures for a broad range of applications.