26.0 



IB.O 



~l 



Period (s) 

 10.0 



6.0 



60- 

 40_ 

 30- 

 20- 

 10- 



60. 



40- 



90- 



20- 



10- 



60- 

 40_ 

 30- 

 20- 

 10- 



60. 

 40. 

 30. 

 20. 

 10. 



60. 

 40. 

 30. 

 20. 

 ID. 



r — r 



1 — I 



~i — I — I — I I I I 



0.06 0.10 0.14 O.IB 



Frequency ( Hz ) 



Figure D-3. 



57 



