Let \(f:[0, \pi] \rightarrow \mathbb{R}\) be a function defined by \(f(x)=\begin{cases}x+\sqrt{2}\, a \sin x, & 0 \leq x<\frac{\pi}{4} \\ 2 x \cot x+b, & \frac{\pi}{4} \leq x \leq \frac{\pi}{2} \\ a \cos 2 x-b \sin x, & \frac{\pi}{2}<x \leq \pi\end{cases}\)
If \(f\) is continuous for \(0 \leq x \leq \pi\), then \(a^{2}+140 b^{2}\) is equal to