Existence and regularity results for a singular parabolic equations with degenerate coercivity

The aim of this paper is to prove existence and regularity of solutions for the following nonlinear singular parabolic problem\begin{document}$ \left\{ \begin{array}{lll} \dfrac{\partial u}{\partial t}-\mbox{div}\left( \dfrac{a(x,t,u,\nabla u)}{(1+|u|)^{\theta(p-1)}}\right) +g(x,t,u) = \dfrac{f}{u^{\gamma}} &\mbox{in}&\,\, Q,\\ u(x,0) = 0 &\mbox{on} & \Omega,\\ u = 0 &\mbox{on} &\,\, \Gamma. \end{array} \right. $\end{document}Here \begin{document}$ \Omega $\end{document} is a bounded open subset of \begin{document}$ I\!\!R^{N} (N>p\geq 2), T>0 $\end{document} and \begin{document}$ f $\end{document} is a non-negative function that belong to some Lebesgue space, \begin{document}$ f\in L^{m}(Q) $\end{document} , \begin{document}$ Q = \Omega \times(0,T) $\end{document} , \begin{document}$ \Gamma = \partial\Omega\times(0,T) $\end{document} , \begin{document}$ g(x,t,u) = |u|^{s-1}u $\end{document} , \begin{document}$ s\geq 1, $\end{document}\begin{document}$ 0\leq\theta< 1 $\end{document} and \begin{document}$ 0<\gamma<1. $\end{document}