1. in the theory of dynamic analysis, that displacement is = A cos wt, where is A is amplitude. how can we get the amplitude value, if just frequency of compressor were known?
2. in dynamic analysis, caesar will classified the case into harmonic, spectrum, time history, and other. what kind of case that make it grouped into "other" case?

1) The problem with a dynamic analysis is that you have to be able to define the dynamic loading. In the case of a harmonic analysis where the loading can be described as A*coswt, you must specify the frequency and either (a) a force, or (b) a displacment. The displacment can be measured, the force is sort of a guess. You then scale the force change its location to "tune" the model's response to the real system in the field.

2) "Other" is mostly used for general "force spectrum" analysis. The only thing "other" does is turn on all the input tabs.