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
运用 R/S 方法，对1951～1997年兰州城市气候的温度、水汽压、相对湿度和日照百分率等指标的冬(1月)、夏(7月)及年平均值进行了分析计算，各项指标的Hurst指数 H 均大于0.5，说明它们存在明显的Hurst现象，反映出兰州市过去47年来气候...运用 R/S 方法，对1951～1997年兰州城市气候的温度、水汽压、相对湿度和日照百分率等指标的冬(1月)、夏(7月)及年平均值进行了分析计算，各项指标的Hurst指数 H 均大于0.5，说明它们存在明显的Hurst现象，反映出兰州市过去47年来气候变化存在趋势性成分即持续性的城市化增暖.至于各项指标的Hurst指数在冬、夏及年平均值间有差异，分析证明这是兰州城市化气候效应强度季节不同所造成.展开更多
为了准确及时检测DDoS(D istributed Den ial of Service)攻击,在网络流量自相似研究基础之上,对检测DDoS攻击的两种方法进行了研究和比较。一种是经典的R/S(rescaled range analysis)方法,另一种是热点方法———小波分析法。给出了两...为了准确及时检测DDoS(D istributed Den ial of Service)攻击,在网络流量自相似研究基础之上,对检测DDoS攻击的两种方法进行了研究和比较。一种是经典的R/S(rescaled range analysis)方法,另一种是热点方法———小波分析法。给出了两种方法检测DDoS攻击的思想和算法。实验表明,对于强DDoS攻击,两种方法都具有较好的效果,对于弱攻击,R/S法难以检测到,而小波分析方法有效。展开更多
基金Project(NCET-05-0413)support by the Program for New Century Excellent Talents in UniversityProject(YB0142112) support by Priming Foundation of East China University of Science and Technology
文摘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.
文摘运用 R/S 方法，对1951～1997年兰州城市气候的温度、水汽压、相对湿度和日照百分率等指标的冬(1月)、夏(7月)及年平均值进行了分析计算，各项指标的Hurst指数 H 均大于0.5，说明它们存在明显的Hurst现象，反映出兰州市过去47年来气候变化存在趋势性成分即持续性的城市化增暖.至于各项指标的Hurst指数在冬、夏及年平均值间有差异，分析证明这是兰州城市化气候效应强度季节不同所造成.
文摘为了准确及时检测DDoS(D istributed Den ial of Service)攻击,在网络流量自相似研究基础之上,对检测DDoS攻击的两种方法进行了研究和比较。一种是经典的R/S(rescaled range analysis)方法,另一种是热点方法———小波分析法。给出了两种方法检测DDoS攻击的思想和算法。实验表明,对于强DDoS攻击,两种方法都具有较好的效果,对于弱攻击,R/S法难以检测到,而小波分析方法有效。
