Nguyen, L.; Le, T.; Huynh, C.; Hoang, T. Machine Learning Applications in Predicting Aluminum Material Thickness from Transmission X-Ray Spectra: A Comparative Study of Feedforward Neural Network (FNN), Convolutional Neural Network (CNN), and Recurrent Neural Network (RNN) Models. VNUHCM Journal of Natural Sciences 2025, 9, 3517-3526.