Table 2.

Compared methods.

Method	Data representation	Domain matching criterion
MMITR	CNN	Mutual information minimization
DAN	CNN	Maximum mean discrepancy (MMD)
STM	—	Kernel mean-matching (KMM)
SSKMDA	Multikernel learning	Hilbert schmidt independence criterion (HSIC)
DTMKL	Multikernel learning	MMD