期刊文献+
共找到2篇文章
< 1 >
每页显示 20 50 100
Multi-scale and multi-fractal analysis of pressure fluctuation in slurry bubble column bed reactor 被引量:1
1
作者 王兴军 胡立舜 +3 位作者 沈军杰 余志楠 王辅臣 于遵宏 《Journal of Central South University of Technology》 EI 2007年第5期696-700,共5页
The Daubechies second order wavelet was applied to decompose pressure fluctuation signals with the gas flux varying from 0.18 to 0.90 m3/h and the solid mass fraction from 0 to 20% and scales 1?9 detail signals and th... The Daubechies second order wavelet was applied to decompose pressure fluctuation signals with the gas flux varying from 0.18 to 0.90 m3/h and the solid mass fraction from 0 to 20% and scales 1?9 detail signals and the 9th scale approximation signals. The pressure signals were studied by multi-scale and R/S analysis method. Hurst analysis method was applied to analyze multi-fractal characteristics of different scale signals. The results show that the characteristics of mono-fractal under scale 1 and scale 2, and bi-fractal under scale 3?9 are effective in deducing the hydrodynamics in slurry bubbling flow system. The measured pressure signals are decomposed to micro-scale signals, meso-scale signals and macro-scale signals. Micro-scale and macro-scale signals are of mono-fractal characteristics, and meso-scale signals are of bi-fractal characteristics. By analyzing energy distribution of different scale signals,it is shown that pressure fluctuations mainly reflects meso-scale interaction between the particles and the bubble. 展开更多
关键词 pressure fluctuation R/S analysis multi-scale MULTI-FRACTAL bubble column bed reactor
在线阅读 下载PDF
Digital watermarking algorithm based on scale-invariant feature regions in non-subsampled contourlet transform domain 被引量:8
2
作者 Jian Zhao Na Zhang +1 位作者 Jian Jia Huanwei Wang 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2015年第6期1310-1315,共6页
Contraposing the need of the robust digital watermark for the copyright protection field, a new digital watermarking algorithm in the non-subsampled contourlet transform (NSCT) domain is proposed. The largest energy... Contraposing the need of the robust digital watermark for the copyright protection field, a new digital watermarking algorithm in the non-subsampled contourlet transform (NSCT) domain is proposed. The largest energy sub-band after NSCT is selected to embed watermark. The watermark is embedded into scaleinvariant feature transform (SIFT) regions. During embedding, the initial region is divided into some cirque sub-regions with the same area, and each watermark bit is embedded into one sub-region. Extensive simulation results and comparisons show that the algorithm gets a good trade-off of invisibility, robustness and capacity, thus obtaining good quality of the image while being able to effectively resist common image processing, and geometric and combo attacks, and normalized similarity is almost all reached. 展开更多
关键词 multi-scale geometric analysis (MGA) non-subsampled contourlet transform (NSCT) scale-invariant featureregion.
在线阅读 下载PDF
上一页 1 下一页 到第
使用帮助 返回顶部