“…A simple approach is to choose the number of PCs for the variance to achieve a predetermined percentage, such as 85%, Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering) ISSN 1673-565X (Print); ISSN 1862-1775 (Online) www.zju.edu.cn/jzus; www.springerlink.com E-mail: jzus@zju.edu.cn termed as cumulative percent variance (CPV) (Jackson, 1991). Other methods for determination, including cross validation, average eigenvalue approach, variance of reconstruction error (VRE) criterion, and fault signal-to-noise ratio (fault SNR), have been proposed to determine the number of the retained PCs (Wold, 1978;Dunia and Qin, 1998;Valle et al, 1999;Tamura and Tsujita, 2007). The cross validation method uses part of the training samples for the model construction, while the rest are compared with the prediction by the model.…”