12.3.5 Long short-term memory neural network -- 12.4 Application examples of deep neural network for microwave modeling -- 12.4.1 High-dimensional parameter-extraction modeling using the hybrid feedforward deep neural network -- 12.4.2 Macromodeling of audio amplifier using long short-term memory neural network -- 12.5 Discussion -- 12.6 Conclusion -- References -- 13 Concluding remarks, open challenges, and future trends -- 13.1 Introduction -- 13.2 Pros and cons of DL -- 13.2.1 High computational efficiency and accuracy -- 13.2.2 Bypassing feature engineering -- 13.2.3 Large amounts of training data -- 13.2.4 High computational burden -- 13.2.5 Deep architectures, not learning -- 13.2.6 Lack of transparency -- 13.3 Open challenges -- 13.3.1 The need for less data and higher efficiency -- 13.3.2 Handling data outside the training distribution -- 13.3.3 Improving flexibility and enabling multi-tasking -- 13.3.4 Counteracting over-fitting -- 13.4 Future trends -- 13.4.1 Few shot, one shot, and zero shot learning -- 13.4.2 Foundation models -- 13.4.3 Attention schemes and transformers -- 13.4.4 Deep symbolic reinforcement learning -- 13.5 Conclusions -- References -- Index. |