In millisecond blast engineering

the key to achieving initiative control of vibration damages by means of wave interference is to ascertain reasonable delay time interval. The designed or selected time of delay is always different from the practical time of delay due to the delay errors of ordinary detonators; and it influences the effect and successful implementation. It is significant to identify practical time of delay in millisecond blasting engineering. The authors have made use of time-energy density analysis based on wavelet transform and time-frequency domain transform techniques

and obtained the reasonable delay time interval by separating every sub-signal from measured millisecond blast vibration signal and comparing the superposition effect of sub-signal in different delay time intervals. The results show that the reasonable delay time interval is not generally a single value

but multi-time-intervals. The method proposed shows a high theoretical and practical value; and it lays a theoretical and technical foundation for the study of controlling and forecasting blast vibrational damages.