Correlation between morphological evolution of splashing drop and
  exerted impact force revealed by interpretation of explainable artificial
  intelligence
Jingzu Yee Daichi Igarashi Pradipto Akinori Yamanaka Yoshiyuki Tagawa
This study reveals a possible correlation between splashing morphology and
the normalized impact force exerted by an impacting drop on a solid surface.
This finding is obtained from a newly proposed feature extraction method and a
subsequent interpretation of the classification of splashing and non-splashing
drops performed by an explainable artificial intelligence (XAI) video
classifier. Notably, the values of the weight matrix elements of the XAI that
correspond to the extracted features are found to change with the temporal
evolution of the drop morphology. We compute the rate of change of the
contributions of each frame with respect to the classification value of a video
as an important index to quantify the contributions of the extracted splashing
and non-splashing features at different impact times to the classification of
the XAI model. Remarkably, the rate computed for the extracted splashing
features is found to closely match the profile of the normalized impact force,
where the splashing features are most pronounced immediately after the
normalized impact force reaches its peak value. This study has provided an
example that clarifies the relationship between the complex morphological
evolution of a splashing drop and physical parameters by interpreting the
classification of an XAI video classifier.