Development of a portable NDE system with advanced signal processing and machine learning for health condition diagnosis of in-service timber utility poles

For ri,1(t), last step is repeated again to extract the second IMF ci,2(t) and ri,2(t). The sifting procedure is repeated until the termination condition of signal decomposition is satisfied. Then the signal xi(t) can be expressed as the combination of several IMFs and a residue ri,M(t), shown as:

i M( )t ( )t ( )t, ,+= =

(3)

where M denotes the total number of IMFs and ci,k(t) denotes kth IMF. Step 4. If i is less than the total number, then i = i+1

and repeat Steps 2 and 3 until i arrives at its maximum value N.