Aiming to detect the weak rail crack signal under strong Wheel-rail Rolling Noise (WRRN) in high-speed railway by Acoustic Emission (AE) technology, a Hurst exponent-improved Adaptive Line Enhancer (ALE) is put forward. The Hurst exponent is adopted to describe the irregularity and fractality property, and is introduced into the cost function of ALE through its power-law relation with the structure function of the fractional Brownian motion so that the optimal objective of the adaptive filter is improved to adapt to the rail crack signal. Compared with the ALE and the Shannon entropy-improved ALE, the proposed method has the best performance. The Hurst exponent-improved ALE not only suppresses the strong WRRN in high-speed condition, but also enhances the rail crack signal and the signal to noise ratio to a large extent. Moreover, with the entire frequency components of the desired signal reserved, the method has the benefits of low computational cost and simple implementation. The research offers a method for extraction of the weak rail crack signal, solves the WRRN problem, and makes AE technology applicable in high-speed rail defect detection.

为了通过声发射（AE）技术检测高速铁路中强轮轨滚动噪声（WRRN）下的弱轨裂纹信号，提出了一种改进了赫斯特指数的自适应线路增强器（ALE）。采用Hurst指数描述不规则性和分形性，并通过幂律与分数布朗运动的结构函数将其引入ALE的成本函数，从而改善了自适应滤波器的最优目标。到铁轨裂纹信号。与ALE和Shannon熵改进的ALE相比，该方法具有最佳的性能。Hurst指数改进的ALE不仅抑制了高速条件下的强WRRN，而且在很大程度上增强了钢轨裂纹信号和信噪比。此外，在保留了所需信号的整个频率分量的情况下，该方法具有计算成本低和实现简单的优点。该研究提供了一种提取弱钢轨裂纹信号的方法，解决了WRRN问题，并使AE技术可应用于高速钢轨缺陷检测。