A Fault Prognosis Strategy Based on Time-Delayed Digraph Model and Principal Component Analysis

Table 2

Online process data for the three methods.

Methods	Current data for online algorithms
PCA	𝑥(𝑘)=𝑥1(𝑘),𝑥2(𝑘),…,𝑥10(𝑘)
DPCA	𝑥(𝑘)=[𝑥1(𝑘),𝑥1(𝑘−1),…,𝑥1(𝑘−𝜏),𝑥2(𝑘),𝑥2(𝑘−1),…,𝑥2(𝑘−𝜏),
	…,𝑥10(𝑘),𝑥10(𝑘−1),…,𝑥10(𝑘−𝜏)]^∗
PCA on synchronized data	𝑥(𝑘)=[𝑥1(𝑘),𝑥2(𝑘+6),𝑥3(𝑘+8),𝑥4(𝑘+8),𝑥5(𝑘+15),𝑥6(𝑘+15),
	𝑥7(𝑘+17),𝑥8(𝑘+17),𝑥9(𝑘+19),𝑥10(𝑘+22)]

^*𝜏=15 according to [9].