A closed cubic surface with edges of length \(L\) is situated in a region containing a non-uniform electric field given by \(\vec{E} = \alpha x\,\hat{i}\), where \(\alpha\) is a positive constant. The cube has two faces perpendicular to the \(x\)-axis located in the planes \(x = d\) and \(x = d + L\) (where \(d > 0\)), while its other four faces are parallel to the \(x\)-axis and bounded by \(0 \le y \le L\) and \(0 \le z \le L\). Taking into account the electric flux through each of the six faces of the cube, what is the net electric charge \(Q_{\text{enc}}\) enclosed by the surface?