An adjustable spatula for forming a smoothly arcuate concave contour in a viscous material and a smoothly arcuate convex contour in the viscous material, independently of each other, with a certainty that the contour of the viscous material is consistent, and with using only one hand. When the evacuation time of a floor is longer than the time for making a car respond to a rescue call from the evacuation floor, the floor is judged as a rescue floor, and when shorter, the floor is judged as a non-rescue floor. The method also includes determining depth weighted color values between two different colorization palettes as a function of the measure of depths of the second composited plane. If a failure is detected, fault-finding mechanisms are activated for identifying a position of a fault and attempting to fix the fault that led to the failure within the advanced process. The remaining IVPs can be solved over the same timespan using the same IRK method and time steps, together with the recorded trajectory from the first propagation.