which appeared in naval and ocean engineering have been solved by applying 

 either the equivalent linearization technique or the perturbation method. 

 However, the complexity involved in this particular nonlinear dynamic system 

 has not been fully explored, and hence it is somewhat difficult to recommend 

 the approach which is most appropriate to solve this particular problem. 

 Some approach suggested during the Seminar appears to be highly desirable, 

 but the approach may not be feasible in practice. For example, the non- 

 linear response of a system may be expressed as follows: 



= f ^(r) X(t-T)df + n ^(?;,Tj :ii(t-T:) x.(t--Tj^T, dTi 



where, the first term represents the linear response, and h(T) can be evaluated 

 from the frequency response function of the system without any difficulty. 

 On the other hand, h(T ,T ) involved in the second term can be evaluated only 



1 2 



through the cross bispectrum of the system. It is unknown, in general, 

 unless the results of either model experiments or full scale trials carried out 

 on the individual mooring system are available. This results in the approach 

 shown in the above equation appears to be not feasible, in practice. 



Judging from the information available On the nonlinear mooring dynamics, 

 the iteration method in the frequency domain appears to be a promising approach. 



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