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WAVELET-BASED ESTIMATOR FOR THE HURST PARAMETERS OF FRACTIONAL BROWNIAN SHEET 被引量:6
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作者 吴量 丁义明 《Acta Mathematica Scientia》 SCIE CSCD 2017年第1期205-222,共18页
It is proposed a class of statistical estimators H = (H1,… ,Hd) for the Hurst parameters H = (H1,… ,Hd) of fractional Brownian field via multi-dimensional wavelet analysis and least squares, which are asymptotic... It is proposed a class of statistical estimators H = (H1,… ,Hd) for the Hurst parameters H = (H1,… ,Hd) of fractional Brownian field via multi-dimensional wavelet analysis and least squares, which are asymptotically normal. These estimators can be used to detect self-similarity and long-range dependence in multi-dimensional signals, which is important in texture classification and improvement of diffusion tensor imaging (DTI) of nuclear magnetic resonance (NMR). Some fractional Brownian sheets will be simulated and the simulated data are used to validate these estimators. We find that when Hi ≥ 1/2, the estimators are accurate, and when Hi 〈 1/2, there are some bias. 展开更多
关键词 detection of long-range dependence SELF-SIMILARITY Hurst parameters waveletanalysis fractional Brownian sheet
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The Recognition of Silk Fabric Defects Based on Biorthogonal Wavelet Analysis and SOM Neural Network
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作者 刘建立 左保齐 《Journal of Donghua University(English Edition)》 EI CAS 2007年第3期313-316,325,共5页
A feasible approach for the recognition of silk fabric defects based on wavelet transform and SOM neural network is proposed in this paper, the indispensable processes of which are defect images denoising and enhancem... A feasible approach for the recognition of silk fabric defects based on wavelet transform and SOM neural network is proposed in this paper, the indispensable processes of which are defect images denoising and enhancement, image edge detection, feature extraction and defects identification. Both geometrical and textmal feature parmnete~ are extracted from the edge image and the enhanced defect image, and utilize SOM neural network to recognize the common defects which silk fabrics have, including warplacking, weft-lacking, double weft, loom bars, oil-stains. Experimental resets show the advantages with high identification correctness and high inspection speed. 展开更多
关键词 silk fabrics defect recognition waveletanalysis neural network
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Theory of Fiber Fluorescence and Wavelet Analysis Using in the Measurement of Bio-medical Temperature
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作者 ZHANG Jing chao, WANG Yu tian (School of Electr. Eng., Yanshan University, Qinhuangdao 066004, CHN) 《Semiconductor Photonics and Technology》 CAS 2002年第3期153-156,共4页
The method of the temperature measurement based on the fluorescence lifetime and fiber transmitting technology is proposed. The certain or uncertain relationship between temperature and optical characteristics of some... The method of the temperature measurement based on the fluorescence lifetime and fiber transmitting technology is proposed. The certain or uncertain relationship between temperature and optical characteristics of some fluorescence material excited by function pulse or square wave pulse, and the temperature relativity of the feature are analyzed. The method based on the wavelet transformation theory is given to acquire temperature signals accurately and to remove the noise. 展开更多
关键词 Theory of fluorescence bio-medical temeprature measurement waveletanalysis
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Spatio-temporal evolution of drought and flood disaster chains in Baoji area from 1368 to 1911 被引量:6
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作者 万红莲 宋海龙 +2 位作者 朱婵婵 张蓓蓓 张咪 《Journal of Geographical Sciences》 SCIE CSCD 2018年第3期337-350,共14页
Based on the collation and statistical analysis of flood and drought information in Baoji area from 1368 to 1911, and in the context of climate change, we investigated the spatio-temporal evolution characteristics of ... Based on the collation and statistical analysis of flood and drought information in Baoji area from 1368 to 1911, and in the context of climate change, we investigated the spatio-temporal evolution characteristics of drought and flood disaster chains in this area during the Ming and Qing dynasties using the methods of moving average, cumulative anomaly and wavelet analysis. The results are as follows:(1) We found a total of 297 drought and flood events from 1368 to 1911 in Baoji. Among these events, droughts and floods occurred separately 191 and 106 times, which accounted for 64.31% and 35.69% of the total events, respectively.(2) We observed distinct characteristics of flood and drought events in Baoji in different phases. The climate was relatively dry from 1368 to 1644. A fluctuant climate phase with both floods and droughts occurred from 1645 to 1804. The climate was relatively wet from 1805 to 1911. Moreover, we observed a pattern of alternating dry and wet periods from 1368 to 1911. In addition, 3 oscillation periods of drought and flood events occurred around 70 a, 110 a and 170 a, which corresponded to sunspot cycles.(3) We also observed an obvious spatial difference in drought and flood events in Baoji. The northern and eastern parts of Weihe River basin were regions with both frequent droughts and floods.(4) The sequential appearance of drought and flood disaster chains in Baoji from 1368 to 1911 was in response to global climate change. Since the 1760s, global climatic deterioration has frequently led to extreme drought and flood events. 展开更多
关键词 Baoji area drought and flood disaster chain climate change spatio-temporal distribution waveletanalysis
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