COHERENCIES 
TEST NO. 207 
A 
25;STR/(RO 
eee (ROLL? 
COHERENCIES rN 
TEST NO. 207 ye - STR/(RO . 
feria t (ROLL}-itt. 
60 
OMEGA 
Fig. 3.20. Coherency of squared rolling process and filtered squared 
rolling process to the stress. 
(From Yamanouchi.??) 
the partial coherencies. The results for two—input, three—input and four—input cases are 
compared in Fig. 3.25. 
This figure indicates that the multiple coherency shows higher levels as more inputs 
. ome . . 2 
are taken into account. Moreover, examining the partial coherencies, y SR-PWR?? 
Ysp?-_rpw and others, at the bottom figure of Fig. 3.25, we find that the contributions of 
rolling and of (roll)?-filters are large compared with the other inputs. This finding sup- 
ports the assumption of quadratic nonlinearity of transverse stress to the rolling motion. 
Figure 3.26 shows the multiple and partial coherencies for the two—inputs and 
three—inputs cases, and here again we find the coherency improves with increasing num- 
ber of inputs, including the (roll)—filtered process. Also the contributions of rolling and 
(roll)*—-filtered are large, compared with the contribution of pitching. The multiple coher- 
ency is very close to 1 around the frequency range in which the output, here the stress, 
has important response to input. 
85 
