在爆破振动监测过程中,为解决低频趋势成分干扰所引起的基线漂移问题,提出了一种基于鲁棒局部均值分解(robust local mean decomposition, RLMD)和均值判比(mean ratio, MR)方法的爆破振动信号基线校正方法。首先,利用RLMD对包含趋势项...在爆破振动监测过程中,为解决低频趋势成分干扰所引起的基线漂移问题,提出了一种基于鲁棒局部均值分解(robust local mean decomposition, RLMD)和均值判比(mean ratio, MR)方法的爆破振动信号基线校正方法。首先,利用RLMD对包含趋势项的振动信号进行自适应分解,生成一系列乘积函数(product functions, PF);随后,通过MR方法筛选出低频趋势项分量,去除这些成分并重构剩余信号,以校正基线漂移。仿真信号分析结果表明,与传统的最小二乘拟合法(ordinary least squares, OLS)和局部均值分解(local mean decomposition, LMD)相比,RLMD方法在提取趋势项方面具有更高的准确性和稳定性,有效避免了模态混叠现象。现场爆破振动监测试验结果显示,与远区振动信号相比,近区实测爆破振动信号受到低频趋势项的干扰更为严重。通过RLMD-MR方法进行基线校正后,信号波形能够有效恢复至基线中心附近,解决了基线漂移问题。展开更多
Two simple, accurate, precise and economic spectrophotometric methods have been developed for simultaneous determination of Atorvastatin calcium (ATR) and Ezetimibe (EZ) in their bulk powder and pharmaceutical dosage ...Two simple, accurate, precise and economic spectrophotometric methods have been developed for simultaneous determination of Atorvastatin calcium (ATR) and Ezetimibe (EZ) in their bulk powder and pharmaceutical dosage form. Method (I) is based on dual wavelength analysis while method (II) is the mean centering of ratio spectra spectrophotometric (MCR) method. In method (I), two wavelengths were selected for each drug in such a way that the difference in absorbance was zero for the second drug. At wavelengths 226.6 and 244 nm EZ had equal absorbance values; therefore, these two wavelengths have been used to determine ATR; on a similar basis 228.6 and 262.8 nm were selected to determine EZ in their binary mixtures. In method II, the absorption spectra of both ATR and EZ with different concentrations were recorded over the range 200-350, divided by the spectrum of suitable divisor of both ATR and EZ and then the obtained ratio spectra were mean centered. The concentrations of active components were then determined from the calibration graphs obtained by measuring the amplitudes at 215-260 nm (peak to peak) for both ATR and EZ. Accuracy and precision of the developed methods have been tested; in addition recovery studies have been carried out in order to confirm their accuracy. On the other hand, selectivities of the methods were tested by application for determination of different synthetic mixtures containing different ratios of the studied drugs. The developed methods have been successfully used for determination of ATR and EZ in their combined dosage form and statistical comparison of the developed methods with the reported spectrophotometric one using F and Student’s t-tests showed no significant difference regarding both accuracy and precision.展开更多
文摘在爆破振动监测过程中,为解决低频趋势成分干扰所引起的基线漂移问题,提出了一种基于鲁棒局部均值分解(robust local mean decomposition, RLMD)和均值判比(mean ratio, MR)方法的爆破振动信号基线校正方法。首先,利用RLMD对包含趋势项的振动信号进行自适应分解,生成一系列乘积函数(product functions, PF);随后,通过MR方法筛选出低频趋势项分量,去除这些成分并重构剩余信号,以校正基线漂移。仿真信号分析结果表明,与传统的最小二乘拟合法(ordinary least squares, OLS)和局部均值分解(local mean decomposition, LMD)相比,RLMD方法在提取趋势项方面具有更高的准确性和稳定性,有效避免了模态混叠现象。现场爆破振动监测试验结果显示,与远区振动信号相比,近区实测爆破振动信号受到低频趋势项的干扰更为严重。通过RLMD-MR方法进行基线校正后,信号波形能够有效恢复至基线中心附近,解决了基线漂移问题。
文摘Two simple, accurate, precise and economic spectrophotometric methods have been developed for simultaneous determination of Atorvastatin calcium (ATR) and Ezetimibe (EZ) in their bulk powder and pharmaceutical dosage form. Method (I) is based on dual wavelength analysis while method (II) is the mean centering of ratio spectra spectrophotometric (MCR) method. In method (I), two wavelengths were selected for each drug in such a way that the difference in absorbance was zero for the second drug. At wavelengths 226.6 and 244 nm EZ had equal absorbance values; therefore, these two wavelengths have been used to determine ATR; on a similar basis 228.6 and 262.8 nm were selected to determine EZ in their binary mixtures. In method II, the absorption spectra of both ATR and EZ with different concentrations were recorded over the range 200-350, divided by the spectrum of suitable divisor of both ATR and EZ and then the obtained ratio spectra were mean centered. The concentrations of active components were then determined from the calibration graphs obtained by measuring the amplitudes at 215-260 nm (peak to peak) for both ATR and EZ. Accuracy and precision of the developed methods have been tested; in addition recovery studies have been carried out in order to confirm their accuracy. On the other hand, selectivities of the methods were tested by application for determination of different synthetic mixtures containing different ratios of the studied drugs. The developed methods have been successfully used for determination of ATR and EZ in their combined dosage form and statistical comparison of the developed methods with the reported spectrophotometric one using F and Student’s t-tests showed no significant difference regarding both accuracy and precision.
