From: Factorial experimentation on photodegradation of historical paper by polychromatic visible radiation
(a) The two levels of the three factors: [O2], RH, and illuminance used in the 23 factorial design of experimentsa | ||
---|---|---|
Low (− 1) | High (1) | |
[O2] (%) | 0 | 21 |
RH (%) | 20 (0.49) | 70 (1.71) |
Ev | 5000 lx | 20,000 lx |
(b) The combinations of conditions used for each experiment in the factorial experimentsb | |||
---|---|---|---|
Experimental run number | [O2] | RH | Ev |
2 | − 1 | − 1 | − 1 |
1 | + 1 | − 1 | − 1 |
3 | − 1 | + 1 | − 1 |
4 | + 1 | + 1 | − 1 |
2 | − 1 | − 1 | + 1 |
1 | + 1 | − 1 | + 1 |
3 | − 1 | + 1 | + 1 |
4 | + 1 | + 1 | + 1 |