(Figure )) or 350 bar H2 (Figure ). In the scatter plots (left side of each quadrant), the 5-D objective is visualized in 3-D. Each scatter point represents a fixed combination of three variables (fH2, ΔH, ΔS in Figure ) and fH2, 𝝆, k in Figure )) and the color coding represents the fraction of total combinations of the two hidden variables, i.e., 6 2 = 36 that exceed the target. In the Figure contour plots, the blue contour delineates the surface at which no combination of (𝝆, k) (Figure (a,c)) or (ΔH, ΔS)