The spacing–burden(S/B) ratio plays significant role on rock fragmentation and proper utilization of explosive energy to minimize the undesirable damage.Low S/B ratio generates fine fragments due to pressure rings co...The spacing–burden(S/B) ratio plays significant role on rock fragmentation and proper utilization of explosive energy to minimize the undesirable damage.Low S/B ratio generates fine fragments due to pressure rings coalescence of two blast holes,whereas boulder generations were observed above optimum S/B ratio.Both conditions are not acceptable because of wastage of explosive energy.Therefore,to resolve this issue,a numerical model study was conducted to optimize the S/B ratio and to envisage its effect on rock fragmentation based on utilization of explosive energy.Finite element simulation tool was used to see the extent of two blast hole influence area variation with varying S/B ratio.The better results were obtained at S/B ratio of 1:2 with optimum utilization of peak explosive energy.The performance was observed based on peak kinetic energy,peak pressure,radial and hoop stresses on centre of the two blast holes,where pressure rings coalescence.展开更多
A semi-fragile content authentication algorithm is proposed for low bit-rate H.264/AVC video in VLC domain. Utilizing the intra prediction mode and coded block pattern in VLC domain, the proposed algorithm chooses tho...A semi-fragile content authentication algorithm is proposed for low bit-rate H.264/AVC video in VLC domain. Utilizing the intra prediction mode and coded block pattern in VLC domain, the proposed algorithm chooses those macro-blocks from which the signature is extracted and constructs content signature at macro-block level according to the relationship among the energies of quantized low-frequency coefficients of sub-macroblocks. The signature is embedded by modifying the trailing coefficients. The experimental results show that the proposed algorithm performs well in visual quality impact and keep the bit-rate basically unchanged. In addition, the algorithm can embed signatures into I, P, B slices simultaneously and remarkably enhances the watermark capacity. By verifying the extracted signature, the algorithm can detect and locate video tampering efficiently.展开更多
文摘The spacing–burden(S/B) ratio plays significant role on rock fragmentation and proper utilization of explosive energy to minimize the undesirable damage.Low S/B ratio generates fine fragments due to pressure rings coalescence of two blast holes,whereas boulder generations were observed above optimum S/B ratio.Both conditions are not acceptable because of wastage of explosive energy.Therefore,to resolve this issue,a numerical model study was conducted to optimize the S/B ratio and to envisage its effect on rock fragmentation based on utilization of explosive energy.Finite element simulation tool was used to see the extent of two blast hole influence area variation with varying S/B ratio.The better results were obtained at S/B ratio of 1:2 with optimum utilization of peak explosive energy.The performance was observed based on peak kinetic energy,peak pressure,radial and hoop stresses on centre of the two blast holes,where pressure rings coalescence.
基金This paper is sponsored by the National Natural Science Foundation of China （No. 60802057, 61071153）, National 863 Plan of China （ 2009AA01Z407 ）, Shanghai Rising-Star Program （10QA1403700）, and Shanghai Educational Development Foundation.
文摘A semi-fragile content authentication algorithm is proposed for low bit-rate H.264/AVC video in VLC domain. Utilizing the intra prediction mode and coded block pattern in VLC domain, the proposed algorithm chooses those macro-blocks from which the signature is extracted and constructs content signature at macro-block level according to the relationship among the energies of quantized low-frequency coefficients of sub-macroblocks. The signature is embedded by modifying the trailing coefficients. The experimental results show that the proposed algorithm performs well in visual quality impact and keep the bit-rate basically unchanged. In addition, the algorithm can embed signatures into I, P, B slices simultaneously and remarkably enhances the watermark capacity. By verifying the extracted signature, the algorithm can detect and locate video tampering efficiently.
