Hexagon design

An experiment based on a hexagon design was carried out with four replications at the origin, producing the following data ... 

Figure 13.17 shows a design similar to the hexagonal design in the previous Figure 13.16, but in this new design only one experiment has been carried out at the center. The experimental design matrix is... 

Figure 13.19 A hexagonal design with extra outer point. DF, = 1, DF = 0.

An extreme effect illustrated with the hexagonal design... 

Fig. 12.17 Equiradial designs fa) Pentagon design (b) Hexagon design.

The designs may be rotated by any angle and still retain the same properties. Certain orientations more commonly used than others are shown in figure 5.5 and table 5.8. We shall see later that the pentagonal and hexagonal design, with addition of centre points, may also be used with a second-order model (see sections V.B and D). 

V.B.6)]. If we wish to do a minimum of experiments for 2 variables only, and to analyse the results according to a quadratic model, then this hexagonal design of only 7 experiments is to be recommended. It would be better to do more than one experiment at the centre point (see table 5.24). 

A hexagonal design with one centre point would be suitable for studying the granulation. This may be carried out at each level of Zj, giving 21 experiments in all. The model is obtained by multiplying the model for the granulation by the second-order model for the scale ... 

To study solvent effects on this complexation reaction, Bruns et al. (1996) prepared 16 ternary mixtures of water, ethanol and acetone, to which fixed quantities of Fe(III) and SCN ions were added. The mixture compositions were specified by the approximately hexagonal design of Table 7A.1, where the concentrations are expressed as proportions of... 

The approximately hexagonal design for studying the complexation of Fe(III) with thiocyanate ions. Xi, X2 and X3 are the proportions, in pseudocomponents, of water, ethanol and acetone, respectively... 

The variables selected for use in optimization of the process were reaction ten erature and the molar ratio of dimethylamine to 4-chloroacetophenone. The experiments were run in sealed reactors. The initial design contained seven experiments (rotatable hexagonal design with center point). Six experiments were equally spaced around the center point that was set at 3 equivalents of dimethylamine and 230 C. The unit variation in the equivalents of dimethylamine was set to 1 molar equivalent, and the unit variation in temperature was set to 20 °C. At the conclusion of this series of experiments, it was determined that the optimum conditions were not within the experimental domain. Consequently, the original study was augmented with additional experiments. 

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