All vehicles are painted, and most automobiles are painted with
multiple layers of different paints. Such multilayer paints can be
used in the forensic discrimination of evidence for traffic accidents. In some traffic accidents, the drivers at fault run away to
avoid punishment. After these drivers escape,they can repair and repaint their vehicles. Because such repainted surfaces may appear
as they did before an accident, the ability to analyze such vehicles
nondestructively is significantly challenging. In fact, although the
surfaces of repainted parts may appear as they did initially, it is
difficult for repair technicians to ensure that the elemental
composition of every layer of paint in repaired parts is the same
as that in the original parts. However,layers with various elemental compositions would produce different X-ray fluorescence