An important application of machine learning techniques
is the
intelligent nondestructive testing of polymers. However, data scarcity
and class imbalance (for real applications) shape some of the involved
challenges. In order to tackle these challenges, an intelligent screening
framework for poly(methyl methacrylate) (PMMA) samples is studied
here. An efficient thermal and experimental test is designed and coupled
with several machine learning tools for quick classification with
four features. Furthermore, a set of sampling techniques are employed/compared;
these techniques are Random oversampling (ROS), synthetic minority
oversampling technique (SMOTE), and adaptive synthetic sampling (ADASYN).
Then, Linear Discriminant Analysis, K-Nearest Neighbor, Naive Bayes,
decision tree, random forest, pattern recognition network, support
vector machine, and ensemble learning are employed for classification.
For assessing these algorithms, their performances are evaluated using
a collection of metrics (i.e., Geometric-mean, F1 score, Matthews
correlation coefficient, accuracy, true positive rate, true negative
rate, positive predictive value, and negative predictive value). Among
others, the average G-mean measures, which is a paramount measure
for assessing the imbalance data, are increased from 75.97% (original
data) to 94.24% (ROS), 93.49% (SMOTE) and 91.27% (ADASYN). That is
a clear proof of successful oversampling. The final results show that
ROS oversampling coupled with Ensemble classification methods can
significantly improve all performance metrics for PMMA classification.