## 1 Introduction
Reduction in the borehole number at the same time of the time-delay;
3. Application of the periodic blasts and the appropriate time between sequences of the blasts;
4. Application of the graduated charge and appropriate timing between the charges;
5. Distribution of the quarry wall in more benches and, as a consequence, reduction in the charge capacity for one borehole. Based on these recommendations, it can be assumed that the use of the time delay method is suitable for the local reduction in vibrations during blasting work. However, this idea was proposed by [PERSON] many years ago [38], and we found out that the accuracy of this method was not at the required level. Moreover, the timing accuracy of the detonation using conventional pyrotechnical detonators always caused a problem, which was finally solved by the introduction of the electronic detonators. The initiation of the electronic detonators enabled a wider application of the appropriate reduction in the vibrations. The occasion has arisen to develop a new theory on the reduction in vibrations by applying electronic detonators. Currently, in blasting operations to regulate vibrations by millisecond timing, electronic detonators are mostly applied; nevertheless, these detonators have many limitations [39]. As the non-electric detonators are exploded at a millisecond timing simultaneously with more boreholes, the vibrations of the blasting operations could be reduced by a reduction in the shot, distribution of the charge capacity in the borehole and by the division into more time sequences. If the technology of blasting operations with a millisecond time delay is used, the accuracy of the delay of the non-electronic detonators is relatively low, with a deflection delay of ca \(\pm\) 3 \(\sigma\), where \(\sigma\) is the relevant deflection. The non-electric detonators prove the following time delay: 9, 17, 25, 33, 42 and 67 milliseconds, regulating the velocity of the chemical combustion [40]. Therefore, the disintegration of the rocks by applying the non-electronic detonators causes uncertainty and non-stability in the regulation of the vibration reduction [41]. The development of highly precise digital electronic detonators enabled a very accurate timing of the blasting operations. The digital electronic detonators provide an accurate delay by applying the chip of the integrated circuit. The delay extent is approximately 1 ms up to 16 s, and the delay deflection is only approximately 0.1 ms. The digital electronic detonators are able to provide an accurate time delay of the combustion according to the requirements in situ. Applying the digital electronic detonators enables us to achieve the required effect of rock disintegration, and, moreover, they provide an adequate protection of the nearby environment from the blasting operations. When the blasting operations are carried out by applying electronic detonators, the vibrations evoked by the blasting operations can be effectively reduced by the adjustment of the convenient sequence of delay. The vibration can be further reduced by applying the method enabling the superimposing of waves in the phase or in the antiphase [42]. [PERSON] and [PERSON] [43] found that if the model of linear superposition is applied for the vibration regulation, the best results can be achieved only if the delay deflection is lower than 1-3 milliseconds. [PERSON] and [PERSON] [42] proposed the method of the combined delay based on the electronic initiation scheme. The optimum delay time could be achieved by simulating the interference of superimposed vibration waves from the individual boreholes. [PERSON] et al. [44] pointed out the abilities of the Hilbert-Huang Transform (HHT) in identifying important features related to millisecond blasting, particularly detonation times. The real delay time can be identified by analyzing the peak distribution of the instantaneous energy. They found that the instantaneous energy of the vibration signal is an accurate indicator of the initiation sequence. [PERSON] et al.