Interesting system of ODE, application in physics?

[atanas1234]

Hi all,
I have a project to do for system of ordinal differential equations and their applications in physics.
One of my tasks is to find where in physics the following system of ordinal differential equations appear:

dA1(x)/dx=f(x).A2(x)
dA2(x)/dx=f(x).A1(x)+ h(x).A2(x)+ g(x).A3(x)
dA3(x)/dx= g(x).A2(x)

Could someone help me?
Thanks

 

[atanas1234]

Also application of higher dimensional system could be useful

dA1(x)/dx=f(x).A4(x)
dA2(x)/dx= g(x).A4(x)
dA3(x)/dx= k(x).A4(x)
dA4(x)/dx=f(x).A1(x)+ g(x).A2(x)+ k(x).A3(x) +h(x).A4(x)

or application of lower dimensional system
dA1(x)/dx=-f(x).A1(x)+ g(x).A2(x)
dA2(x)/dx= g(x).A1(x)+ f(x).A2(x)

 

[atanas1234]

I found some suitable articles, but it is not exactly what I need
Any way something like this could help me
http://www.iop.org/EJ/abstract/0953-4075/42/5/055504/
this Is Stimulated Raman adiabatic passage analogues in classical physics
or here in the arxiv
http://arxiv.org/abs/0812.0361
If some could give something similar it will be grate