Ontology-Based Noise Source Identification and Key Feature Selection: A Case Study on Tractor Cab

Table 6

Implementation of SWRL rules for feature extraction.

Rule 1	Feature 1 (ignition frequency check); Checking whether the parotic noise signal is related to the ignition frequency
	Input the ignition frequency (specific numerical value); if the rule matches, it is inferred that the parotic noise signals are related to a specific vibrating part. The feature of this correlation is represented by the “ignition frequency”
Rule 2	Feature 2 (peak frequency check in the noise source); Checking whether the peak frequencies in the noise source correspond to the peak frequencies in the vibration source
	Rule 2.1 (specially for/applies to the engine and cab)
	Rule 2.2 (specially for/applies to the air filter, muffler, and back panel)
	Input the peak frequency (specific numerical value); if the rule matches, it is inferred that the parotic noise signals are related to a specific vibrating part. The feature of this correlation is represented by the “peak frequency”
Rule 3	Feature 3 (correlation check and identification); Calculating the correlation between the parotic noise signal and the location signal of the tractor and identifying the locations exhibiting a specific correlation (four different degrees of correlation)
	Rule 3.1 (determining the degree of correlation)
	Input the correlation coefficient (specific numerical value); if the rule matches, it is inferred that the parotic noise signals are related to a certain position. The feature of this correlation is represented by the “correlation”
	Rule 3.2 (determining the degree of correlation and the locations); Rule 3.2 is divided into four rules corresponding to Levels 1, 2, 3, and 4
	Rule 3.2.1 (applies to Level 1); Rule 3.2.2 (applies to Level 2); Rule 3.2.3 (applies to Level 3); Rule 3.2.4 (applies to Level 4)
	Input the correlation coefficient (specific numerical value); if the rule matches, it is inferred that the parotic noise signals are related to a specific vibrating part. The feature of this correlation is represented by the correlation. The degree of correlation is Level 1, 2, 3, or 4