已知 \(f\left( x \right) = \ln x - \frac{x}{4} + \frac{3}{{4x}}\) , \(g\left( x \right) = - {x^2} - 2ax + 4\) ,若对 \(\forall {{x}_{1}}\in \left ( {0,2} \right ]\) , \(\exists {{x}_{2}}\in \left [ {1,2} \right ]\) ,使得 \(f\left( {{x_1}} \right) \geqslant g\left( {{x_2}} \right)\) 成立,则\(a\)的取值范围是___.
参考答案:\([-\frac {1} {8},+\infty )\)