How to Calculate Power Output of a Linear Alternator With Reciprocating Motion?

hi guys, 
Im working on a project and i faced some problem hope that you will help me to solve it. 
i want to use linear alternator to generate electricity because i have a reciprocating motion and what i want to know how to calculate the power generated by this linear alternator.
if someone has a good knowledge about linear alternator please contact me.
thank you all.