Here, ω ∈ is a weighting between the two parts of the bridge DoE objective function relating to the phase stability and viscosity test results, respectively; 𝑫 is the design scaled to be between 0 and 1; 𝐸 -[U(𝑫)] is the expected utility relating to estimation of, or prediction from, a machine learning model of the phase stability response and d(𝑫) is the average