Table 1 Variables and levels in central composite design.
From: Experimental study on the drag reduction performance of sodium alginate in saline solutions
Factor | Lowest level (− 1) | Median (0) | Highest level (+ 1) |
|---|---|---|---|
Q (ml/min) | 350 | 400 | 450 |
Cp (ppm) | 500 | 1000 | 1500 |
Cs (%) | 3 | 6 | 9 |
