I’m quite suspicious that you’ve declared f as a scalar variable and you seem to be calling it as a function in f(Q_1,Q_2_v). There are multiple quantities here that you haven’t defined for us, such as f_v, Q_2_v, g, etc. so nobody can fully appreciate what you’re doing.
I’m going to mark this one as Nonconvex, because I strongly suspect that it is, but if you provide further clarification we can pull down that tag.