湖底回波包络包含了湖底沉积物的结构和物理性质的信息,可以作为沉积物分类的特征。用传统的H ilbert变换提取宽带回波包络存在一些固有的缺点。该文中,采用线性相位的双正交小波,对湖底回波解析信号的实部和虚部分别进行离散正交小波变...湖底回波包络包含了湖底沉积物的结构和物理性质的信息,可以作为沉积物分类的特征。用传统的H ilbert变换提取宽带回波包络存在一些固有的缺点。该文中,采用线性相位的双正交小波,对湖底回波解析信号的实部和虚部分别进行离散正交小波变换,提取合适尺度上的小波系数的模值作为包络特征矢量。它可以采用M a llat快速算法,运算量少,提取的包络特征矢量维数少,能简化目标识别的算法。对实测的湖底回波数据进行特征提取和分类的仿真实验也表明,采用这种方法得到的包络特征是一种稳健、有效的特征,能获得较高的正确识别率。展开更多
Determination of dissolution rate of alumina is one of the classical problems in aluminum electrolysis. A novel method which can measure the dissolution rate of alumina was presented. Effect of factors on dissolution ...Determination of dissolution rate of alumina is one of the classical problems in aluminum electrolysis. A novel method which can measure the dissolution rate of alumina was presented. Effect of factors on dissolution rate of alumina was studied intuitively and roundly using transparent quartz electrobath and image analysis techniques. Images about dissolution process of alumina were taken at an interval of fixed time from transparent quartz electrobath of double rooms. Gabor wavelet transforms were used for extracting and describing the texture features of each image. After subsampling several times, the dissolution rate of alumina was computed using these texture features in local neighborhood of samples. Regression equation of the dissolution rate of alumina was obtained using these dissolution rates. Experiments show that the regression equation of the dissolution rate of alumina is y=-0.000 5x^3＋0.024 0x^2-0.287 3x＋ 1.276 7 for Na3AIF6-AIF3-Al2O3-CaF2-LiF- MgF2 system at 920 ℃.展开更多
Partial discharge detection in power transformers is discussed using a new approach that exploit the broad band of the Rogowski coils and the potential of two signal processing tools： discrete wavelet transform and e...Partial discharge detection in power transformers is discussed using a new approach that exploit the broad band of the Rogowski coils and the potential of two signal processing tools： discrete wavelet transform and empirical mode decomposition. Detecting and analyzing incipient activities of partial discharge can provide useful information to diagnostics and prognostics about transformer insulation. So, partial discharge signals embedded in the electric current at ground conductor are measured using the Rogowski coil. These signals are submitted to noise suppression and the partial discharges waveforms are extracted through different ways： using discrete wavelet transform and using empirical mode decomposition. The comparison of these two methods show that the extraction with discrete wavelet transform results in a faster and simpler algorithm than the empirical mode decomposition. But this one produces more precise waveforms due its adaptive characteristic.展开更多
文摘湖底回波包络包含了湖底沉积物的结构和物理性质的信息,可以作为沉积物分类的特征。用传统的H ilbert变换提取宽带回波包络存在一些固有的缺点。该文中,采用线性相位的双正交小波,对湖底回波解析信号的实部和虚部分别进行离散正交小波变换,提取合适尺度上的小波系数的模值作为包络特征矢量。它可以采用M a llat快速算法,运算量少,提取的包络特征矢量维数少,能简化目标识别的算法。对实测的湖底回波数据进行特征提取和分类的仿真实验也表明,采用这种方法得到的包络特征是一种稳健、有效的特征,能获得较高的正确识别率。
基金Projects(51101104,51072121) supported by the National Natural Science Foundation of ChinaProject(LS2010109) supported by the Key Laboratory Foundation of Liaoning Province,China
文摘Determination of dissolution rate of alumina is one of the classical problems in aluminum electrolysis. A novel method which can measure the dissolution rate of alumina was presented. Effect of factors on dissolution rate of alumina was studied intuitively and roundly using transparent quartz electrobath and image analysis techniques. Images about dissolution process of alumina were taken at an interval of fixed time from transparent quartz electrobath of double rooms. Gabor wavelet transforms were used for extracting and describing the texture features of each image. After subsampling several times, the dissolution rate of alumina was computed using these texture features in local neighborhood of samples. Regression equation of the dissolution rate of alumina was obtained using these dissolution rates. Experiments show that the regression equation of the dissolution rate of alumina is y=-0.000 5x^3＋0.024 0x^2-0.287 3x＋ 1.276 7 for Na3AIF6-AIF3-Al2O3-CaF2-LiF- MgF2 system at 920 ℃.
文摘Partial discharge detection in power transformers is discussed using a new approach that exploit the broad band of the Rogowski coils and the potential of two signal processing tools： discrete wavelet transform and empirical mode decomposition. Detecting and analyzing incipient activities of partial discharge can provide useful information to diagnostics and prognostics about transformer insulation. So, partial discharge signals embedded in the electric current at ground conductor are measured using the Rogowski coil. These signals are submitted to noise suppression and the partial discharges waveforms are extracted through different ways： using discrete wavelet transform and using empirical mode decomposition. The comparison of these two methods show that the extraction with discrete wavelet transform results in a faster and simpler algorithm than the empirical mode decomposition. But this one produces more precise waveforms due its adaptive characteristic.
