小波变换软阈值去噪在粗晶材料超声检测中的应用

本研究多尺度小波分析方法在粗晶材料超声检测信号增强中的应用。在分析结构噪声，电噪声和缺陷信号的小波变换特性的基础上，提出一种用一个尺度间变化的门限闭值来抑制噪声的小波变换系数，并以各尺度缺陷信号的能量关系形成权值，加权重构信号来提高信噪比。实验结果表明，该方法具有很好的去噪效果，增强了粗晶材料缺陷的检出率。

De-noising in ultrasonic detection of coarse-grained materials by wavelet transform soft-thresholding

To suppress the adverse effects of the structure noise and the electrical noise, the application of multiscale wavelet transform to ultrasonic detection of coarse-grained materials is discussed. According to the characteristics of the wavelet transform on the different scale of the structure noise, the electrical noise and the defect signal, we present an algorithm such that wavelet transform coefficients of noise are filtered by a changing threshold on the different scale and the detection signal is reconstructed with appropriate weight in order to enhance the signal-to-noise ratio. Experimental results show that this new method is effective, and the defect is detected easily.