Integration: Heuristics update and validation
This phase was carried out to do the screening of the prototype products, and to iterate within the design process to enhance product performance, as part of the cyclic part in Figure 2, integrating thus consumer assessment in the product realization phase. Depending on the experimental tests, the ranking of attributes, and their interactions, a series of heuristics rules could be transformed into additional restrictions in the algorithm. Table 3 contains some of the potential actions increasing or reducing the value of a specific attribute, depending on the case. For instance, the presence of white residues after rubbing is mainly related to the generation of microfoam (emulsifiers "catching" air), so the use of silicones could also reduce this problem. Another possible solution is to add up to a 2% low HLB emulsifier and allow the HLB to be lower than the RHLB. This solution will not only remove the microfoam but also increase the viscosity of the formulation. In this case, (5) will change to:
\(0.5\leq\left(\sum{y_{i} x_{i}}+\sum{y_{j} x_{j}}+\sum{y_{k} x_{k}}\right)\left(\sum{x_{r}\text{HLB}_{r}}\right)-\left(\sum{x_{i}\text{RHLB}_{i}+\sum{x_{j}\text{RHLB}_{j}}+\sum{x_{k}\text{RHLB}_{k}}}\right)\ \left(\sum{y_{r} x_{r}}\right)\leq 1\ \) (6)
This example emphasizes the importance of heuristics updating, and the set of equations required for properties prediction in the new design iteration.