基于小波滤波的低场NMR纤维上油率检测新方法

摘要

A new wavelet transform-based method for measuring the oil content of fiber with low-field NMR was introduced. Firstly, free induction decays (FID) of the standard fibers were collected and used to calculate the calibration curve through linear fitting. Secondly, the signals of the testing fiber were collected with different numbers of averages, and wavelet soft threshold was used to filter each of the collected signals. Finally, the oil content of the fiber was calculated by comparing the filtered NMR signals with the calibration curve. Practical applications were used to validate the effectiveness of the new method.%针对目前低场核磁共振纤维上油率检测存在的问题,提出了一种基于小波变换的纤维上油率检测新方法.首先,用低场核磁共振采集标准纤维自由感应衰减信号进行线性拟合得到定标曲线；然后,用测试纤维采集多组叠加次数不同的核磁共振信号,并分别进行小波软阈值滤波；最后,将滤波后的多组结果代入定标曲线计算纤维的上油率.检测结果和实际应用表明小波软阈值滤波可有效去除纤维FID信号中的噪声并大幅缩短检测时间.此方法可为低场核磁共振纤维上油率快速、准确检测奠定基础.