Decoupling Deep Domain Adaptation Method for Class-imbalanced Learning with Domain Discrepancy

In a wide range of classification tasks, training data will produce class-imbalance due to collection difficulties in some classes, which leads to prediction biases on minority classes. For the class-imbalanced problem, existing researches are usually based on the assumption that the training dataset and the test dataset are from similar distributions. In reality, both of the datasets often come from domains with different distributions, which challenges generalization performances of models. In this paper, a decoupling deep domain adaptation method is proposed to overcome these problems. Based on the adversarial domain adaptation model, the method uses a two-stage training strategy which decouples representation learning and classifier adjustment. The results of experiments under scenarios of bearing fault diagnosis and digit images classification with class-imbalance and domain discrepancy show that the effect of the combination of domain adaptation method and specific decoupling strategy is better than that of one-stage training only using resampling or cost-sensitive methods in the domain adaptation model.