Secondly, the wavelet packet theory and its application are discussed.The multi-index fault diagnosis model of diesel valve is established based on Mahalanobis distance.

• 然后，研究了小波包理论在柴油机气门故障诊断中的应用，建立了基于马氏距离法的柴油机气门故障多指标诊断模型，在实例应用中取得了良好的效果。