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\begin{document}

\title[On the Petrovesky equation ]{Global existence and blow-up of a
Petrovsky equation with general nonlinear dissipative and source terms }
\author{Mosbah Kaddour}

\address{Faculty of Mathematics and Computer Science,\\
Mohamed Boudiaf University-M'Sila 28000, Algeria}


\email{mosbah\_kaddour@yahoo.fr}

\author{Farid Messelmi}
\address{Department of Mathematics and LDMM Laboratory Ziane Achour, \\ University of
Djelfa 17000, Algeria}
\email{foudimath@yahoo.fr}

\subjclass{Primary:93C20 ; Secondary: 93D15 }
\keywords{Global Existence, Blow-up, Nonlinear source, Nonlinear dissipative, Petrovsky Equation}

\begin{abstract}
This work studies the initial boundary value problem for the Petrovsky
equation with nonlinear damping
\begin{equation*}
\frac{\partial ^{2}u}{\partial t^{2}}+\Delta ^{2}u-\Delta u^{\prime
}+\left\vert u\right\vert ^{p-2}u+\alpha g\left( u^{\prime }\right) =\beta
f\left( u\right) \text{ in }\Omega \times \left[ 0,+\infty \right[,
\end{equation*}
where $\Omega $ is open and bounded domain in $\mathbb{R}^{n}$ with a smooth
boundary $\partial \Omega =\Gamma$, $\alpha$, and $\beta >0$. For the
nonlinear continuous term $f\left( u\right) $ and for $g$ continuous,
increasing, satisfying $g$ $\left( 0\right) $ $=0$, under suitable
conditions, the global existence of the solution is proved by using the
Faedo-Galerkin argument combined with the stable set method in $%
H_{0}^{2}\left( \Omega \right)$. Furthermore, we show that this solution
blows up in a finite time when the initial energy is negative.
\end{abstract}

\maketitle

\section{Introduction}

This paper devoted to the global existence, uniqueness, and the blow-up of
solutions for the nonlinear general Petrovsky equation
\begin{equation}
\left\{
\begin{array}{c}
\frac{\partial ^{2}u}{\partial t^{2}}+\Delta ^{2}u\left( t\right) -\Delta
u^{\prime }\left( t\right) +\left\vert u\right\vert ^{p-2}u\left( t\right)
+\alpha g\left( u^{\prime }\left( t\right) \right) =\beta f\left( u\left(
t\right) \right) ,\text{ in }\Omega \times \mathbb{R}^{+}, \\
u=\partial _{\eta }u=0,\ \text{on}\ \Gamma \times \left[ 0,+\infty \right[ ,
\\
u(x,0)=u_{0}(x),\text{ }u^{\prime }(x,0)=u_{1}(x)\ \text{in }\Omega .%
\end{array}%
\right.  \label{1}
\end{equation}%
Recently, in the absence of the strong damping term $-\Delta u^{\prime
}\left( t\right) $ and in the case where $\beta f\left( u\left( t\right)
\right) =-q\left( x\right) u\left( x,t\right) +\left\vert u\right\vert
^{p-2}u\left( t\right) $ for $g$ continuous, increasing, satisfying $g\left(
0\right) =0$, and $q:\Omega \rightarrow \mathbb{R}^{+},$ a bounded function,
the problem\ (\ref{1}) becomes the following
\begin{equation*}
\frac{\partial ^{2}u}{\partial t^{2}}+\Delta ^{2}u\left( t\right) +q\left(
x\right) u\left( x,t\right) +g\left( u^{\prime }\left( t\right) \right) =0,%
\text{ in }\Omega \times \mathbb{R}^{+}\text{.}
\end{equation*}%
This equation together with initial and boundary conditions of Dirichlet
type was considered by Guesmia in \cite{Guesmia}, he proved a global
existence and a regularity result of the solution, the author under suitable
growth conditions on $g$ showed that the solution decays exponentially if $g$
behaves like a linear function, whereas the decay is of a polynomial order
otherwise. Without the strong damping term $-\Delta u^{\prime }\left(
t\right) $ with $\alpha g\left( u^{\prime }\left( t\right) \right)
=\left\vert u^{\prime }\left( t\right) \right\vert ^{\sigma -2}u^{\prime
}\left( t\right) $ and $\beta f\left( u\left( t\right) \right) =\left(
b+1\right) \left\vert u\left( t\right) \right\vert ^{p-2}u\left( t\right) $,
$b>0,$ the problem (\ref{1}) reduced to the following problem
\begin{equation*}
\frac{\partial ^{2}u}{\partial t^{2}}+\Delta ^{2}u\left( t\right)
+\left\vert u^{\prime }\left( t\right) \right\vert ^{\sigma -2}u^{\prime
}\left( t\right) =b\left\vert u\left( t\right) \right\vert ^{p-2}u\left(
t\right) ,\text{ in }\Omega \times \mathbb{R}^{+},
\end{equation*}%
this problem has been considered by Messaoudi in \cite{Messaoudi}, where he
investigated the global existence and blow-up of solution. More precisely,
he showed that solutions with any initial data continue to exist globally in
time if $\sigma \geq p$ and blow-up in finite time if $\sigma <p$ and the
initial energy is negative. He used a new method introduced by Georgiev and
Todorova \cite{GeorgievTodorova} based on the fixed point theorem for the
proof. In \cite{WuandTsai}, Wu and Tsai showed that the solution of the
problem considered in \cite{Messaoudi}$\ $is global under some conditions.
Also, Chen and Zhou \cite{ChenandZhou} studied the blow-up of the solution
of the same problem as in \cite{Messaoudi}. In the presence of the strong
damping, in the case where $\beta f\left( u\left( t\right) \right) =\left(
b+1\right) \left\vert u\left( t\right) \right\vert ^{p-2}u\left( t\right) $,
$g\left( u^{\prime }\left( t\right) \right) =\left\vert u^{\prime }\left(
t\right) \right\vert ^{\sigma -1}u^{\prime }\left( t\right) ,$ $b>0,$
general Petrovsky problem as in (\ref{1}) becomes%
\begin{equation}
\frac{\partial ^{2}u}{\partial t^{2}}+\Delta ^{2}u\left( t\right) -\Delta
u^{\prime }\left( t\right) +\left\vert u^{\prime }\left( t\right)
\right\vert ^{\sigma -1}u^{\prime }\left( t\right) =b\left\vert u\left(
t\right) \right\vert ^{p-1}u\left( t\right) \text{,}  \label{P1}
\end{equation}%
this problem was considered by Li et al. \cite{Li}, in \cite{PiskinPolat}
and in \cite{NOUR}, the authors obtained global existence, uniform decay of
solutions without any interaction between $p$ and $\sigma $, the blow-up of
the solution result was established when $\sigma <p$ . Very recently, Pi\c{s}%
kin and Polat \cite{PiskinPolat} studied the decay of the solution of the
problem (\ref{P1}). In this paper, our aim is to extend the results of \cite%
{Messaoudi}, \cite{WuandTsai} and others' established in a bounded domain to
a general problem as in (\ref{1}). The nonlinear term $f$ in (\ref{1}) likes
$f\left( u\left( x,t\right) \right) =a\left( x\right) \left\vert u\left(
t\right) \right\vert ^{r-2}u\left( t\right) -b\left( x\right) \left\vert
u\left( t\right) \right\vert ^{q-2}u\left( t\right) $ with $r>q\geq 1$ and $%
a\left( x\right) ,$ $b\left( x\right) >0,$ and $g$ in (\ref{1}) likes $%
g\left( u^{\prime }\left( x,t\right) \right) =\alpha \left( x\right)
\left\vert u^{\prime }\left( t\right) \right\vert ^{\sigma -2}u^{\prime
}\left( t\right) $ with $\sigma \geq 2$ for $\alpha \ :\Omega \rightarrow
\mathbb{R}^{+}$ a function, satisfying $\alpha _{1}\geq \alpha \left(
x\right) \geq \alpha _{0}>0$. For these purposes, we must establish the
global existence of solution for (\ref{1}), we use the variational approach
of Faedo--Galerkin approximation combined with the monotonous, compactness,
and the stable set method as in \cite{Messaoudi}, \cite{ChenandZhou} and in
\cite{PiskinPolat} with some modification in some passages to derive the
blow-up result in the infinite time of the solution.

\section{Hypotheses}

Let us state the precise hypotheses on $p$, $g,$ and $f$. Let $p$ be a
positive number with
\begin{equation}
2<p\leq \frac{2n-6}{n-4}\left( n\geq 5\right) \left( 2\leq p<\infty \text{
if }n=1,2,3,4\right) ,  \tag{H1}  \label{H1}
\end{equation}%
$g$ is an odd increasing $C^{1}$ function and
\begin{equation}
\left\{
\begin{array}{c}
xg\left( x\right) \geq d_{0}\left\vert x\right\vert ^{\sigma },\text{ }%
\forall x\in \mathbb{R},\text{ }p>\sigma \geq 2, \\
\left\vert g\left( x\right) \right\vert \leq d_{1}\left\vert x\right\vert
+d_{2}\left\vert x\right\vert ^{\sigma -1},\text{ }\forall x\in \mathbb{R},%
\text{ }p>\sigma \geq 2,\text{ }d_{i}\geq 0.%
\end{array}%
\right.  \tag{H2}  \label{H2}
\end{equation}%
Let $f\left( x,s\right) \in C^{1}\left( \Omega \times \mathbb{R}\right) $,
satisfies:%
\begin{equation}
sf\left( x,s\right) +k_{1}\left( x\right) \left\vert s\right\vert \geq
pF\left( x,s\right) ,\text{ }p>2,  \tag{H3}  \label{H3}
\end{equation}%
and the growth conditions%
\begin{equation}
\left\{
\begin{array}{c}
\left\vert f\left( x,s\right) \right\vert \leq l_{1}\left( \left\vert
s\right\vert ^{\theta }+k_{2}\left( x\right) \right) , \\
\left\vert f_{s}\left( x,s\right) \right\vert \leq l_{1}\left( \left\vert
s\right\vert ^{\theta -1}+k_{3}\left( x\right) \right) \text{ in }\Omega
\times \mathbb{R},%
\end{array}%
\right.  \tag{H4}  \label{H4}
\end{equation}%
where $F\left( x,s\right) =\int_{0}^{s}f\left( x,\zeta \right) d\zeta $,
with some $l_{0},$ $l_{1}>0$ and the non-negative functions $k_{1}\left(
x\right) ,$ $k_{2}\left( x\right) ,$ $k_{3}\left( x\right) \in L^{\infty
}\left( \Omega \right) $, a.e. $x\in \Omega ,$ and $1<\theta \leq \frac{%
\sigma }{2}<\frac{p}{2}.$

\section{Local Existence}

In this section, we establish a local existence result for (\ref{1}) under
the assumptions on $f,$ $g,$ and $p$.

\begin{theorem}
\label{theorem1}Let\ $\left( u_{0},u_{1}\right) \in W\cap L^{p}(\Omega
)\times H_{0}^{2}\left( \Omega \right) \cap L^{2\sigma -2}(\Omega )$. Assume
that (\ref{H1})-(\ref{H4}) hold. Then problem (\ref{1}) has a unique weak
solution $u\left( t\right) $ satisfying:
\begin{gather}
u\in L^{\infty }(0,T;W\cap L^{p}(\Omega )),  \label{6b} \\
u^{\prime }\in L^{\infty }(0,T;H_{0}^{2}\left( \Omega \right) ),  \label{6b1}
\\
g\left( u^{\prime }\left( t\right) \right) .u^{\prime }\left( t\right) \in
L^{1}\left( 0,T;L^{1}(\Omega )\right) ,  \label{6b2} \\
u^{\prime \prime }\in L^{\infty }(0,T;L^{2}(\Omega )),  \label{6b3}
\end{gather}%
where
\begin{equation*}
H_{0}^{2}\left( \Omega \right) =\left\{ \varphi \in H^{2}\left( \Omega
\right) :\varphi =\partial _{\eta }\varphi =0\text{ on }\partial \Omega
\right\} ,
\end{equation*}%
and%
\begin{equation*}
W=\left\{ \varphi \in H^{4}\left( \Omega \right) \cap H_{0}^{2}\left( \Omega
\right) :\Delta \varphi =\partial _{\eta }\Delta \varphi =0\text{ on }%
\partial \Omega \right\} .
\end{equation*}
\end{theorem}
Note that throughout this paper, $C$ denotes a generic positive constant
depending on $\Omega $ and as all given constants, which may be different
from line to line, and is capable of being examined and modified.

\begin{proof}
We adopt the Galerkin method to construct a global solution. Let $T>0$ be a
fixed, and denote by $V_{m}$ the space generated by $\left\{ \varphi _{1},%
\text{ }\varphi _{2},...,\text{ }\varphi _{m}\right\} ,$ where the set $%
\left\{ \varphi _{m};\text{ }m\in \mathbb{N}\right\} $ is a basis of $%
L^{2}(\Omega ),$ $H_{0}^{2}\left( \Omega \right) $, and $H^{4}\left( \Omega
\right) \cap H_{0}^{2}\left( \Omega \right) .$ We construct approximate
solutions $u_{m}$ $\left( m=1,2,3,...\right) $ in the form%
\begin{equation*}
u_{m}(t)=\underset{j=1}{\overset{m}{\sum }}K_{jm}(t)w_{j},
\end{equation*}%
where $K_{jm}$ are determined by the following ordinary differential
equations:%
\begin{eqnarray}
\left( u_{m}^{\prime \prime },w_{j}\right) +\left( \Delta u_{m},\Delta
w_{j}\right) +\left( \nabla u_{m}^{\prime },\nabla w_{j}\right) &&  \label{6}
\\
+\left( \left\vert u_{m}\right\vert ^{p-2}u_{m},w_{j}\right) +\alpha \left(
g\left( u_{m}^{\prime }\right) ,w_{j}\right) &=&\beta \left( f\left(
u_{m}\right) ,w_{j}\right) ,  \notag
\end{eqnarray}%
\begin{eqnarray}
u_{m}\left( 0\right) &=&u_{0m}=\sum_{i=1}^{m}\left( u_{0},w_{j}\right) w_{j}%
\overset{\text{as\ }m\longrightarrow \infty }{\longrightarrow }u_{0}\
\label{7} \\
&&\text{in }H^{4}\left( \Omega \right) \cap H_{0}^{2}\left( \Omega \right)
\cap L^{p}(\Omega )\text{ },  \notag
\end{eqnarray}%
\begin{eqnarray}
u_{m}^{\prime }\left( 0\right) &=&u_{1m}=\sum\limits_{i=1}^{m}\left(
u_{1},w_{j}\right) w_{j}\overset{\text{as\ }m\longrightarrow \infty }{%
\longrightarrow }u_{1}\   \label{8} \\
&&\text{in }H_{0}^{2}\left( \Omega \right) \cap L^{2\sigma -2}(\Omega ),
\notag
\end{eqnarray}%
with $u_{0},$ $u_{1}$ are given functions on $\Omega $, by virtue of the
theory of ordinary differential equations, the system (\ref{6})-(\ref{8})
has a unique local solution on some interval $\left[ 0,t_{m}\right) $. We
claim that for any $T>0$, such a solution can be extended to the whole
interval $\left[ 0,T\right] $, as a consequence of the a priori estimates
that shall be proven in the next step. We denote by $C,$ $C_{k}$ or $c_{k}$
the constants which are independent of $m$, the initial data $u_{0}$ and $%
u_{1}$.

Multiplying the equation (\ref{6}) by $K_{jm}^{\prime }(t)$ and performing
the summation over $j=1,...,m$, the integration par parts gives\qquad
\begin{equation}
E_{m}^{\prime }\left( t\right) +\left\vert \nabla u_{m}^{\prime }\left(
t\right) \right\vert ^{2}+\alpha \left( g\left( u_{m}^{\prime }\left(
t\right) \right) ,u_{m}^{\prime }\left( t\right) \right) =0,\text{ }\forall
t\geq 0\text{,}  \label{9}
\end{equation}%
where
\begin{equation}
E_{m}\left( t\right) =\frac{1}{2}\left\vert u_{m}^{\prime }(t)\right\vert
^{2}+\frac{1}{2}\left\vert \Delta u_{m}(t)\right\vert ^{2}+\frac{1}{p}%
\left\Vert u_{m}(t)\right\Vert _{p}^{p}-\beta \int_{\Omega }F\left(
x,u_{m}(t)\right) dx,  \label{10}
\end{equation}%
by (\ref{H3}), and Young\ inequality, we have%
\begin{gather}
-\int_{\Omega }F\left( x,u_{m}\right) dx\geq -\frac{1}{p}\int_{\Omega
}k_{1}\left( x\right) \left\vert u_{m}\right\vert dx-\frac{1}{p}\int_{\Omega
}u_{m}f\left( x,u_{m}\right) dx  \label{11} \\
\geq -\varepsilon C_{\ast }^{2}\left\vert \Delta u_{m}(t)\right\vert
^{2}-C_{\varepsilon }\left\vert k_{1}\left( x\right) \right\vert ^{2}-\frac{1%
}{p}\int_{\Omega }u_{m}f\left( x,u_{m}\right) dx,  \notag
\end{gather}%
by using hypotheses (\ref{H4}), Young's inequality yields
\begin{gather}
\frac{1}{p}\int_{\Omega }u_{m}f\left( x,u_{m}\right) dx\leq \frac{1}{p}%
\left\vert f\left( x,u_{m}\right) \right\vert \left\vert u_{m}\right\vert
\notag \\
\leq \frac{l_{1}^{2}}{p}\varepsilon \int_{\Omega }\left( \left\vert
u_{m}\right\vert ^{2\theta }+\left\vert k_{2}\left( x\right) \right\vert
^{2}\right) dx+\frac{c\left( \varepsilon ,p\right) }{p^{2}}\int_{\Omega
}\left\vert u_{m}\right\vert ^{2}dx  \notag \\
=\frac{l_{1}^{2}}{p}\varepsilon \left\Vert u_{m}\right\Vert _{2\theta
}^{2\theta }+\frac{l_{1}^{2}}{p}\varepsilon \left\vert k_{2}\left( x\right)
\right\vert ^{2}+\frac{c\left( \varepsilon ,p\right) }{p^{2}}\left\Vert
u_{m}\right\Vert _{p}^{2}  \label{12} \\
\leq \frac{l_{1}^{2}}{p}\varepsilon \left( \frac{p-2\theta }{p}+\frac{%
2\theta }{p}\left\Vert u_{m}\right\Vert _{p}^{p}\right) +\frac{l_{1}^{2}}{p}%
\varepsilon \left\vert k_{2}\left( x\right) \right\vert ^{2}  \notag \\
+C^{\prime }\left( \varepsilon ,p\right) +\frac{\text{ }1}{p^{2}}\left\Vert
u_{m}\right\Vert _{p}^{p},  \notag
\end{gather}%
substituting (\ref{12}) in (\ref{11}), and chosen $\varepsilon \leq
C_{0}=\min \left( \frac{1}{2C_{\ast }^{2}};\frac{p}{2\theta l_{1}^{2}+1}%
\right) $, (\ref{10}) becomes
\begin{equation}
E_{m}\left( t\right) \geq \frac{1}{2}\left\vert u_{m}^{\prime
}(t)\right\vert ^{2}+C_{1}\left\vert \Delta u_{m}(t)\right\vert
^{2}+C_{2}\left\Vert u_{m}\right\Vert _{p}^{p}-C_{3}\left(
1+K_{1}+K_{2}\right) ,  \label{13}
\end{equation}%
or%
\begin{equation}
\left\vert u_{m}^{\prime }(t)\right\vert ^{2}+\left\vert \Delta
u_{m}(t)\right\vert ^{2}+\left\Vert u_{m}\right\Vert _{p}^{p}\leq
C_{4}\left( E_{m}\left( t\right) +K_{1}+K_{2}+1\right) ,  \label{14}
\end{equation}%
where
\begin{gather*}
0<C_{1}\leq \left( 1-C_{0}C_{\ast }^{2}\right) ,\text{ }0<C_{2}\leq \left(
\frac{1}{p}-\frac{2\theta l_{1}^{2}+1}{p^{2}}C_{0}\right) , \\
C_{3}=\max \left( C_{\varepsilon };\frac{l_{1}^{2}}{p}\varepsilon ;C^{\prime
}\left( \varepsilon ,p\right) +\frac{l_{1}^{2}}{p}\varepsilon \frac{%
p-2\theta }{p}\right) , \\
C_{4}=\max \left( \frac{1}{\min \left( \frac{1}{2},C_{1},C_{2}\right) }%
,C_{3}\right) .
\end{gather*}%
Thus, it follows from (\ref{9}), and (\ref{13}) that, for any $m=1,2,...,$
and $t\geq 0,$%
\begin{gather}
\left\vert u_{m}^{\prime }(t)\right\vert ^{2}+\left\vert \Delta
u_{m}(t)\right\vert ^{2}+\left\Vert u_{m}\left( t\right) \right\Vert
_{p}^{p}+\int_{0}^{t}\left\vert \nabla u_{m}^{\prime }\left( s\right)
\right\vert ^{2}ds  \label{15} \\
+\alpha \int_{0}^{t}\left( g\left( u_{m}^{\prime }\left( s\right) \right)
,u_{m}^{\prime }\left( s\right) \right) ds\leq C_{4}\left( E_{m}\left(
0\right) +K_{1}+K_{2}+1\right) .  \notag
\end{gather}%
By assumption (\ref{H2})-(\ref{H4}), according to the H\"{o}lder's
inequality, we have%
\begin{gather}
\left\vert \int_{\Omega }F\left( x,u_{0m}\right) dx\right\vert \leq \frac{1}{%
p}\int_{\Omega }k_{1}\left( x\right) \left\vert u_{0m}\right\vert dx+\frac{1%
}{p}\int_{\Omega }u_{0m}f\left( x,u_{0m}\right) dx  \label{16} \\
\leq C\left( \left\vert u_{m}(0)\right\vert ^{2}+\left\vert k_{1}\left(
x\right) \right\vert ^{2}+\left\Vert u_{m}\left( 0\right) \right\Vert
_{p}^{p}+\left\vert k_{2}\left( x\right) \right\vert ^{2}+\left\vert
u_{m}\left( 0\right) \right\vert ^{2}\right) .  \notag
\end{gather}%
Then using (\ref{7}), (\ref{8}), (\ref{9}), and (\ref{10}) we obtain that%
\begin{gather}
E_{m}\left( t\right) \leq E_{m}\left( 0\right) =\frac{1}{2}\left\vert
u_{1m}\right\vert ^{2}+\frac{\text{ }1}{p}\left\Vert u_{0m}\right\Vert
_{p}^{p}  \notag \\
+\frac{1}{2}\left\vert \Delta u_{0m}\right\vert ^{2}-\beta \int_{\Omega
}F\left( x,u_{0m}\right) dx  \label{17} \\
\leq C_{4}\left( \left\vert u_{1m}\right\vert ^{2}+\left\Vert
u_{0m}\right\Vert _{p}^{p}+\left\vert \Delta u_{0m}\right\vert
^{2}+\left\vert u_{0m}\right\vert ^{2}+K_{1}+K_{2}\right) \leq C,  \notag
\end{gather}%
for some $C>0$, where $K_{1}=\left\Vert k_{1}\right\Vert _{\infty }^{2},$ $%
K_{2}=\left\Vert k_{2}\right\Vert _{\infty }^{2}.$

Hence, for any $t\geq 0$, and $m=1,2,...,$ from (\ref{15}), and (\ref{17})
we get
\begin{equation}
\left\vert u_{m}^{\prime }(t)\right\vert ^{2}+\left\vert \Delta
u_{m}(t)\right\vert ^{2}+\int_{0}^{t}\left\vert \nabla u_{m}^{\prime }\left(
s\right) \right\vert ^{2}ds+\left\Vert u_{m}\left( t\right) \right\Vert
_{p}^{p}+\alpha \int_{0}^{t}\int_{\Omega }g\left( u_{m}^{\prime }\left(
s\right) \right) u_{m}^{\prime }\left( s\right) dxds\leq C.  \label{18}
\end{equation}%
By the growth conditions, the estimate (\ref{18}), and as $2\theta \leq p,$
we have
\begin{equation*}
\left\vert f\left( u_{m}\right) \right\vert ^{2}\leq Cl_{1}\left( \left\vert
u_{m}\right\vert ^{2\theta }+\left\vert k_{2}\left( x\right) \right\vert
^{2}\right) \leq C\left( \left\vert \left\vert u_{m}\right\vert \right\vert
_{p}^{2\theta }+\left\Vert k_{2}\right\Vert _{\infty }^{2}\right) \leq C.
\end{equation*}%
With this estimate we can extend the approximate solution $u_{m}\left(
t\right) $ to the interval $\left[ 0,T\right] $ and the following a priori
estimates%
\begin{equation}
\left\{
\begin{array}{l}
u_{m}\text{ is bounded in}\ L^{\infty }\left( 0,T;L^{p}(\Omega )\right) , \\
u_{m}^{\prime }\text{ is bounded in}\ L^{\infty }\left( 0,T;L^{2}(\Omega
)\right) , \\
\nabla u_{m}^{\prime }\text{ is bounded in}\ L^{2}\left( 0,T;L^{2}(\Omega
)\right) , \\
g\left( u_{m}^{\prime }\right) .u_{m}^{\prime }\text{ is bounded in}\
L^{1}\left( \Omega \times \left( 0,T\right) \right) , \\
\Delta u_{m}(t)\text{ is bounded in}\ L^{\infty }\left( 0,T;L^{2}(\Omega
)\right) , \\
f\left( u_{m}\right) \text{ is bounded in}\ L^{\infty }\left(
0,T;L^{2}(\Omega )\right) ,%
\end{array}%
\right.  \label{19}
\end{equation}%
hold.
\end{proof}

\begin{lemma}
There exists a constant $K>0$ such that%
\begin{equation*}
\left\vert \left\vert g\left( u_{m}^{\prime }\left( t\right) \right)
\right\vert \right\vert _{L^{\frac{\sigma }{\sigma -1}}\left( \Omega \times %
\left[ 0,T\right] \right) }\leq K,
\end{equation*}%
for all $m\in\mathbb{N}.$
\end{lemma}

\begin{proof}
From (\ref{H2}), Holder's, and Young's inequalities gives%
\begin{gather*}
\int_{0}^{T}\int_{\Omega }\left\vert g\left( u_{m}^{\prime }\right)
\right\vert ^{\frac{\sigma }{\sigma -1}}dxdt=\int_{0}^{T}\int_{\Omega
}\left\vert g\left( u_{m}^{\prime }\right) \right\vert \left\vert g\left(
u_{m}^{\prime }\right) \right\vert ^{\frac{1}{\sigma -1}}dxdt \\
\leq \int_{0}^{T}\int_{\Omega }\left\vert g\left( u_{m}^{\prime }\left(
t\right) \right) \right\vert \left( d_{1}\left\vert u_{m}^{\prime }\left(
t\right) \right\vert +d_{2}\left\vert u_{m}^{\prime }\left( t\right)
\right\vert ^{\sigma -1}\right) ^{\frac{1}{\sigma -1}}dxdt \\
\leq C\int_{0}^{T}\int_{\Omega }\left\vert g\left( u_{m}^{\prime }\left(
t\right) \right) \right\vert \left( \left\vert u_{m}^{\prime }\left(
t\right) \right\vert ^{\frac{1}{\sigma -1}}+\left\vert u_{m}^{\prime }\left(
t\right) \right\vert \right) dxdt \\
=C\int_{0}^{T}\int_{\Omega }\left\vert g\left( u_{m}^{\prime }\left(
t\right) \right) \right\vert \left\vert u_{m}^{\prime }\left( t\right)
\right\vert ^{\frac{1}{\sigma -1}}dxdt \\
+C\int_{0}^{T}\int_{\Omega }\left\vert g\left( u_{m}^{\prime }\left(
t\right) \right) \right\vert \left\vert u_{m}^{\prime }\left( t\right)
\right\vert dxdt \\
\leq \frac{\sigma -1}{\sigma }\int_{0}^{T}\int_{\Omega }\left\vert g\left(
u_{m}^{\prime }\right) \right\vert ^{\frac{\sigma }{\sigma -1}}dxdt+C\left(
\sigma \right) \int_{0}^{T}\int_{\Omega }\left\vert u_{m}^{\prime }\left(
t\right) \right\vert ^{\frac{\sigma }{\sigma -1}}dxdt \\
+C\int_{0}^{T}\int_{\Omega }\left\vert g\left( u_{m}^{\prime }\left(
t\right) \right) \right\vert \left\vert u_{m}^{\prime }\left( t\right)
\right\vert dxdt,
\end{gather*}%
therefore%
\begin{gather*}
\frac{1}{\sigma }\int_{0}^{T}\int_{\Omega }\left\vert g\left( u_{m}^{\prime
}\left( t\right) \right) \right\vert ^{\frac{\sigma }{\sigma -1}}dxdt\leq
C\left( \sigma \right) \int_{0}^{T}\int_{\Omega }\left\vert u_{m}^{\prime
}\left( t\right) \right\vert ^{\frac{\sigma }{\sigma -1}}dxdt \\
+C\int_{0}^{T}\int_{\Omega }\left\vert g\left( u_{m}^{\prime }\left(
t\right) \right) \right\vert \left\vert u_{m}^{\prime }\left( t\right)
\right\vert dxdt \\
\leq C\int_{0}^{T}\left\vert \left\vert u_{m}^{\prime }\left( t\right)
\right\vert \right\vert _{2}^{\frac{\sigma }{\sigma -1}}dt+C\int_{0}^{T}%
\int_{\Omega }\left\vert g\left( u_{m}^{\prime }\left( t\right) \right)
\right\vert \left\vert u_{m}^{\prime }\left( t\right) \right\vert dxdt,
\end{gather*}%
hence, by (\ref{19}), we deduce
\begin{equation*}
\int_{0}^{T}\int_{\Omega }\left\vert g\left( u_{m}^{\prime }\left( t\right)
\right) \right\vert ^{\frac{\sigma }{\sigma -1}}dxdt\leq K.
\end{equation*}
\end{proof}

\begin{lemma}
There exists a constant $M>0$ such that%
\begin{equation*}
\left\vert u_{m}^{\prime \prime }(t)\right\vert +\left\vert \Delta
u_{m}^{\prime }(t)\right\vert +\int_{0}^{T}\left\vert \nabla u_{m}^{\prime
\prime }\left( t\right) \right\vert dt\leq M,
\end{equation*}%
for all $m\in\mathbb{N}.$
\end{lemma}

\begin{proof}
From (\ref{6}) we obtain%
\begin{equation*}
\left\vert u_{m}^{\prime \prime }(0)\right\vert \leq \left\vert
u_{0m}\right\vert ^{p-1}+\left\vert \Delta ^{2}u_{0m}\right\vert +\left\vert
\Delta u_{1m}\right\vert +\alpha \left\vert g\left( u_{1m}\right)
\right\vert +\beta \left\vert f\left( u_{0m}\right) \right\vert ,
\end{equation*}%
by (\ref{H4}) we have
\begin{equation*}
\left\vert f\left( u_{0m}\right) \right\vert ^{2}\leq l_{1}\left( \left\vert
u_{0m}\right\vert ^{2\theta }+\left\vert k_{2}\left( x\right) \right\vert
^{2}\right) \leq C\left( \left\vert \left\vert \Delta u_{0m}\right\vert
\right\vert _{2}^{2\theta }+\left\Vert k_{2}\right\Vert _{\infty
}^{2}\right) ,
\end{equation*}%
Since $g\left( u_{1m}\right) $ is bounded in $L^{2}\left( \Omega \right) $
by (\ref{H2}), from (\ref{7}) and (\ref{8}) we obtain%
\begin{equation*}
\left\vert u_{m}^{\prime \prime }(0)\right\vert \leq C.
\end{equation*}%
Differentiating (\ref{6}) with respect to $t$, we get%
\begin{gather}
\left( u_{m}^{\prime \prime \prime },w_{j}\right) +\left( \Delta
^{2}u_{m}^{\prime },w_{j}\right) -\left( \Delta u_{m}^{\prime \prime
},w_{j}\right) +\left( p-1\right) \left( \left\vert u_{m}\right\vert
^{p-2}u_{m}^{\prime },w_{j}\right)  \notag \\
+\alpha \left( g^{\prime }\left( u_{m}^{\prime }\right) u_{m}^{\prime \prime
},w_{j}\right) =\beta \left( f^{\prime }\left( u_{m}\right) u_{m}^{\prime
},w_{j}\right) .  \label{20}
\end{gather}%
Multiplying it by $K_{jm}^{\prime \prime }(t)$ and summing over $j$ from $1$
to $m$ , according to the H\"{o}lder's inequality, to find%
\begin{gather}
\frac{1}{2}\frac{d}{dt}\left( \left\vert u_{m}^{\prime \prime
}(t)\right\vert ^{2}+\left\vert \Delta u_{m}^{\prime }\left( t\right)
\right\vert ^{2}\right) +\left\vert \nabla u_{m}^{\prime \prime }\left(
t\right) \right\vert ^{2}+\alpha \left( g^{\prime }\left( u_{m}^{\prime
}\right) u_{m}^{\prime \prime },u_{m}^{\prime \prime }\right)  \label{21} \\
\leq \left( p-1\right) \int_{\Omega }\left\vert u_{m}\right\vert
^{p-2}\left\vert u_{m}^{\prime }\right\vert \left\vert u_{m}^{\prime \prime
}\right\vert dx+\beta \int_{\Omega }\left\vert f^{\prime }\left(
u_{m}\right) \right\vert \left\vert u_{m}^{\prime }\right\vert \left\vert
u_{m}^{\prime \prime }\right\vert dx.  \notag
\end{gather}%
By choosing $\lambda $ satisfies the inequalities
\begin{equation*}
\left\{
\begin{array}{l}
\lambda +1\leq \min \left( \frac{p}{2\left( \theta -1\right) },\frac{n}{n-4}%
\right) \text{ if }n\geq 5, \\
\lambda +1\leq \frac{p}{2\left( \theta -1\right) }\text{ if }n=1,2,3,4,%
\end{array}%
\right.
\end{equation*}%
then by using (\ref{H4}), estimates (\ref{19}) and generalized H\"{o}lder's
inequality, we deduce that
\begin{gather}
\int_{\Omega }\left\vert f^{\prime }\left( u_{m}\right) \right\vert
\left\vert u_{m}^{\prime }\right\vert \left\vert u_{m}^{\prime \prime
}\right\vert dx  \notag \\
\leq \left\Vert l_{1}\left( \left\vert u_{m}\right\vert ^{\theta
-1}+k_{3}\left( x\right) \right) \right\Vert _{2\left( \lambda +1\right)
}^{\lambda }\left\vert \left\vert u_{m}^{\prime }\right\vert \right\vert
_{2\left( \lambda +1\right) }\left\Vert u_{m}^{\prime \prime }\right\Vert
_{2}  \notag \\
\leq C\left( \left\Vert \left\vert u_{m}\right\vert ^{\theta -1}\right\Vert
_{2\left( \lambda +1\right) }^{\lambda }+\left\Vert k_{3}\left( x\right)
\right\Vert _{2\left( \lambda +1\right) }^{\lambda }\right) \left\vert
\left\vert u_{m}^{\prime }\right\vert \right\vert _{2\left( \lambda
+1\right) }\left\Vert u_{m}^{\prime \prime }\right\Vert _{2}  \notag \\
\leq C\left( \left\Vert u_{m}\right\Vert _{p}^{\lambda \left( \theta
-1\right) }+\left\Vert k_{3}\left( x\right) \right\Vert _{p}^{\lambda
}\right) \left\vert \left\vert \Delta u_{m}^{\prime }\right\vert \right\vert
_{2}\left\Vert u_{m}^{\prime \prime }\right\Vert _{2}  \notag \\
\leq C_{5}\left( \left\vert u_{m}^{\prime \prime }(t)\right\vert
^{2}+\left\vert \Delta u_{m}^{\prime }\left( t\right) \right\vert
^{2}\right) ,  \label{22}
\end{gather}%
where $C_{1}$ and $C_{2}$ are positive constants independent of $m$ and $%
t\in \left[ 0,T\right] .$

By same manner, using condition (\ref{H1}), Young's inequality, Sobolev
embedding, and estimate (\ref{19}) we reach to
\begin{gather}
\int_{\Omega }\left\vert u_{m}\right\vert ^{p-2}\left\vert u_{m}^{\prime
}\right\vert \left\vert u_{m}^{\prime \prime }\right\vert dx\leq \left\Vert
\left\vert u_{m}\right\vert ^{p-2}\right\Vert _{n}\left\Vert u_{m}^{\prime
}\right\Vert _{\frac{2n}{n-2}}\left\Vert u_{m}^{\prime \prime }\right\Vert
_{2}  \notag \\
\leq C\left\vert \left\vert \Delta u_{m}^{\prime }\right\vert \right\vert
_{2}\left\Vert u_{m}^{\prime \prime }\right\Vert _{2}\leq C_{5}\left(
\left\vert u_{m}^{\prime \prime }(t)\right\vert ^{2}+\left\vert \Delta
u_{m}^{\prime }\left( t\right) \right\vert ^{2}\right) .  \label{22b}
\end{gather}%
Combining (\ref{21}), (\ref{22}) and (\ref{22b}) we deduce
\begin{gather*}
\frac{1}{2}\frac{d}{dt}\left( \left\vert u_{m}^{\prime \prime
}(t)\right\vert ^{2}+\left\vert \Delta u_{m}^{\prime }\left( t\right)
\right\vert ^{2}\right) +\left\vert \nabla u_{m}^{\prime \prime }\left(
t\right) \right\vert ^{2}+\alpha \left( g^{\prime }\left( u_{m}^{\prime
}\right) u_{m}^{\prime \prime },u_{m}^{\prime \prime }\right) \\
\leq C_{6}\left( \left\vert u_{m}^{\prime \prime }(t)\right\vert
^{2}+\left\vert \Delta u_{m}^{\prime }\left( t\right) \right\vert
^{2}\right) .
\end{gather*}%
Integrating the last inequality over $(0,t)$ and applying Gronwall's lemma,
we obtain%
\begin{equation*}
\left\vert u_{m}^{\prime \prime }(t)\right\vert +\left\vert \Delta
u_{m}^{\prime }\left( t\right) \right\vert +\int_{0}^{t}\left\vert \nabla
u_{m}^{\prime \prime }\left( t\right) \right\vert ^{2}ds\leq C\text{ for all
}t\geq 0.
\end{equation*}%
Therefore%
\begin{gather}
u_{m}^{\prime \prime }\text{ is bounded in}\ L^{\infty }\left(
0,T;L^{2}(\Omega )\right) ,  \notag \\
\Delta u_{m}^{\prime }\text{ is bounded in}\ L^{\infty }\left(
0,T;L^{2}(\Omega )\right) ,  \label{23} \\
\nabla u_{m}^{\prime \prime }\text{ is bounded in}\ L^{2}\left(
0,T;L^{2}(\Omega )\right) ,  \notag
\end{gather}%
it follows from (\ref{23}), $\left( u_{m}^{\prime }\right) $ is bounded in$\
L^{\infty }\left( 0,T;H_{0}^{2}(\Omega )\right) .$

Furthermore, by applying the Lions-Aubin compactness Lemma in \cite{Lions2},
we claim that
\begin{equation}
u_{m}^{\prime }\text{ is compact in}\ L^{2}\left( 0,T;L^{2}(\Omega )\right) ,
\label{24}
\end{equation}
From (\ref{19}) and (\ref{23}), there exists a subsequence of $\left(
u_{m}\right) $, still denote by $\left( u_{m}\right) $, such that%
\begin{equation}
\left\{
\begin{array}{c}
u_{m}\longrightarrow u\ \text{weak star in}\ L^{\infty }\left(
0,T;H_{0}^{2}(\Omega )\right) \text{,} \\
u_{m}\longrightarrow u\ \text{strongly in}\ L^{2}\left( 0,T;L^{2}(\Omega
)\right) \text{,} \\
u_{m}^{\prime }\longrightarrow u^{\prime }\ \text{weak star in}\ L^{\infty
}\left( 0,T;H_{0}^{2}(\Omega )\right) \text{,} \\
u_{m}^{\prime }\longrightarrow u^{\prime }\ \text{strongly in}\ L^{2}\left(
0,T;L^{2}(\Omega )\right) \text{,} \\
u_{m}^{\prime \prime }\longrightarrow u^{\prime \prime }\ \text{weak star in}%
\ L^{\infty }\left( 0,T;L^{2}(\Omega )\right) \text{,} \\
g\left( u_{m}^{\prime }\right) \longrightarrow \chi \ \text{weak star in}\
L^{\frac{\sigma }{\sigma -1}}\left( \Omega \times \left( 0,T\right) \right)
\text{,} \\
f\left( u_{m}\right) \longrightarrow \zeta \ \text{weak star in}\ L^{\infty
}\left( 0,T;L^{2}(\Omega )\right) \text{.}%
\end{array}%
\right.  \label{27}
\end{equation}%
Using the compactness of $H_{0}^{2}(\Omega )$ to $L^{2}(\Omega )$, it is
easy to see that%
\begin{equation*}
\int_{0}^{T}\int_{\Omega }\left\vert u_{m}\right\vert
^{p-2}u_{m}vdxdt\rightarrow \int_{0}^{T}\int_{\Omega }\left\vert
u\right\vert ^{p-2}uvdxdt,\text{ for all }v\in L^{\sigma }\left(
0,T;H_{0}^{2}(\Omega )\right) ,
\end{equation*}%
as $m\rightarrow \infty .$

By (\ref{H2}), and estimates (\ref{27}) we have
\begin{equation*}
g\left( u_{m}^{\prime }\right) \longrightarrow g\left( u^{\prime }\right)
\text{ a.e.in }\Omega \times \left( 0,T\right) .
\end{equation*}%
Therefore, from \cite[Chapter1,Lemma1.3]{Lions2}, we infer that
\begin{equation*}
g\left( u_{m}^{\prime }\right) \longrightarrow g\left( u^{\prime }\right) \
\text{weak star in}\ L^{\frac{\sigma }{\sigma -1}}\left( 0,T;L^{\frac{\sigma
}{\sigma -1}}\right) \text{,}
\end{equation*}%
as $m\rightarrow \infty ,$ and this implies that%
\begin{equation*}
\int_{0}^{T}\int_{\Omega }g\left( u_{m}^{\prime }\right) vdxdt\rightarrow
\int_{0}^{T}\int_{\Omega }g\left( u^{\prime }\right) vdxdt\ \text{\ for all }%
v\in L^{\sigma }\left( 0,T;H_{0}^{2}(\Omega )\right) .
\end{equation*}%
By the same manner using the growth conditions in (\ref{H4}) and estimate (%
\ref{27}), we see that%
\begin{equation*}
\int_{0}^{T}\int_{\Omega }\left\vert f\left( u_{m}\right) \right\vert ^{%
\frac{\theta +1}{\theta }}dxdt
\end{equation*}%
is bounded and
\begin{equation*}
f\left( u_{m}\right) \longrightarrow f\left( u\right) \text{ a.e.in }\Omega
\times \left( 0,T\right) ,
\end{equation*}%
then
\begin{equation*}
f\left( u_{m}\right) \longrightarrow f\left( u\right) \ \text{weak star in}\
L^{\frac{\theta +1}{\theta }}\left( 0,T;L^{\frac{\theta +1}{\theta }}\right)
\text{,}
\end{equation*}%
as $m\rightarrow \infty ,$ and this implies that
\begin{equation*}
\int_{0}^{T}\int_{\Omega }f\left( u_{m}\right) vdxdt\rightarrow
\int_{0}^{T}\int_{\Omega }f\left( u\right) vdxdt\ \text{\ for all }v\in
L^{\theta }\left( 0,T;H_{0}^{2}(\Omega )\right) .
\end{equation*}%
It follows at once from all estimates that for each fixed $v\in L^{\theta
}\left( 0,T;H_{0}^{2}(\Omega )\right) \cap L^{\sigma }\left(
0,T;H_{0}^{2}(\Omega )\right) ,$
\begin{gather*}
\int_{0}^{T}\int_{\Omega }\left( u_{m}^{\prime \prime }+\Delta
^{2}u_{m}-\Delta u_{m}^{\prime }+\left\vert u_{m}\right\vert ^{\rho
}u_{m}+\alpha g\left( u_{m}^{\prime }\right) -\beta f\left( u_{m}\right)
\right) vdxdt \\
\rightarrow \int_{0}^{T}\int_{\Omega }\left( u^{\prime \prime }+\Delta
^{2}u-\Delta u^{\prime }+\left\vert u\right\vert ^{p-2}u+\alpha g\left(
u^{\prime }\right) -\beta f\left( u\right) \right) vdxdt,
\end{gather*}%
as $m\rightarrow \infty .$ Consequently
\begin{gather*}
\int_{0}^{T}\int_{\Omega }\left( u^{\prime \prime }+\Delta ^{2}u-\Delta
u^{\prime }+\left\vert u\right\vert ^{p-2}u+\alpha g\left( u^{\prime
}\right) -\beta f\left( u\right) \right) vdxdt=0, \\
\forall v\in L^{\theta }\left( 0,T;H_{0}^{2}(\Omega )\right) \cap L^{\sigma
}\left( 0,T;H_{0}^{2}(\Omega )\right) .
\end{gather*}%
This means that the problem admit a weak solution $u$ satisfying (\ref{1}),
and (\ref{6b})-(\ref{6b3}).
\end{proof}

\begin{theorem}
\label{theorem2}Under the hypotheses of the Theorem \ref{theorem1}, we have
the solution $u$ given by Theorem \ref{theorem1}, is unique.
\end{theorem}

\begin{proof}
Let $u$\ and $v$\ are two solutions, in the sense of the Theorem \ref%
{theorem1}. Then $w=u-v$\ satisfies%
\begin{gather}
w^{\prime \prime }+\left( \Delta ^{2}u-\Delta ^{2}v\right) -\Delta w^{\prime
}+\alpha \left( g\left( u^{\prime }\right) -g\left( v^{\prime }\right)
\right)  \notag \\
+(\left\vert u\right\vert ^{p-2}u-\left\vert v\right\vert ^{p-2}v)=\beta
\left( f\left( u\right) -f\left( v\right) \right) ,  \label{28}
\end{gather}%
\begin{equation}
w(0)=w^{\prime }(0)=0\ \text{in}\ \Omega ,  \label{29}
\end{equation}%
\begin{equation}
w=\ \partial _{\eta }w=0\ \text{on}\ \Sigma ,  \label{30}
\end{equation}%
\begin{equation}
w\in L^{p}(0,T;W\cap L^{p}(\Omega )),  \label{31}
\end{equation}%
\begin{equation}
w^{\prime }\in L^{2}(0,T;H_{0}^{2}\left( \Omega \right) ).  \label{32}
\end{equation}%
Let's multiply the two members of (\ref{28}) by $w^{\prime }$ and integrate
on $\Omega $. According to the Green's formula and conditions (\ref{30}),
integrating by part the result on $[0,t]$, using conditions (\ref{29}) to
find that%
\begin{gather}
\frac{1}{2}\left( \left\vert w^{\prime }(t)\right\vert ^{2}+\left\vert
\Delta w\right\vert ^{2}\right) \leq \int_{0}^{t}\int_{\Omega }\left\vert
\left\vert u\right\vert ^{p-2}u-\left\vert v\right\vert ^{p-2}v\right\vert
\left\vert w^{\prime }\right\vert dxds  \label{33} \\
+\beta \int_{0}^{t}\int_{\Omega }\left\vert f\left( u\right) -f\left(
v\right) \right\vert \left\vert w^{\prime }\right\vert dxds.  \notag
\end{gather}%
According to the H\"{o}lder's, Young's inequalities, condition (\ref{H1}),
the estimates (\ref{27}) the first term on the right-hand side of (\ref{33})
can be estimated as follows:%
\begin{gather}
\int_{0}^{t}\int_{\Omega }\left\vert \left\vert u\right\vert
^{p-2}u-\left\vert v\right\vert ^{p-2}v\right\vert \left\vert w^{\prime
}\right\vert dxds  \notag \\
\leq \left( p-1\right) \int_{0}^{t}\left( \left\Vert \left\vert u\right\vert
^{p-2}\right\Vert _{L^{n}(\Omega )}+\left\Vert \left\vert v\right\vert
^{p-2}\right\Vert _{L^{n}(\Omega )}\right) \left\Vert w\right\Vert _{L^{%
\frac{2n}{n-2}}(\Omega )}\left\Vert w^{\prime }\right\Vert _{L^{2}(\Omega
)}ds  \notag \\
\leq C\int_{0}^{t}\left( \left\Vert u\right\Vert _{L^{n\left( p-2\right)
}(\Omega )}^{p-2}+\left\Vert v\right\Vert _{L^{n\left( p-2\right) }(\Omega
)}^{p-2}\right) \left\Vert \Delta w\right\Vert _{L^{2}(\Omega )}\left\Vert
w^{\prime }\right\Vert _{L^{2}(\Omega )}ds  \label{34} \\
\leq C\int_{0}^{t}\left( \left\Vert \Delta u\right\Vert _{L^{2}\left( \Omega
\right) }^{p-2}+\left\Vert \Delta v\right\Vert _{L^{2}(\Omega
)}^{p-2}\right) \left\Vert \Delta w\right\Vert _{L^{2}(\Omega )}\left\Vert
w^{\prime }\right\Vert _{L^{2}(\Omega )}ds  \notag \\
\leq C\int_{0}^{t}\left( \left\vert w^{\prime }(s)\right\vert
^{2}+\left\vert \Delta w\left( s\right) \right\vert ^{2}\right) ds.  \notag
\end{gather}%
Now let $U_{\varepsilon }=\varepsilon u+\left( 1-\varepsilon \right) v,$ $%
0\leq \varepsilon \leq 1$, by the growth conditions, for the second term of
the right side to (\ref{33}), we have
\begin{gather*}
\left\vert \int_{0}^{t}\int_{\Omega }\left\vert f\left( u\right) -f\left(
v\right) \right\vert \left\vert w^{\prime }\right\vert dxdt\right\vert
=\left\vert \int_{0}^{t}\int_{\Omega }\int_{0}^{1}\frac{d}{d\varepsilon }%
f\left( U_{\varepsilon }\right) d\varepsilon w^{\prime }dxds\right\vert \\
\leq \int_{0}^{t}\int_{\Omega }\left\vert \int_{0}^{1}\frac{d}{d\varepsilon }%
f\left( U_{\varepsilon }\right) d\varepsilon \right\vert \left\vert
w^{\prime }\right\vert dxds \\
\leq \int_{0}^{t}\int_{\Omega }\int_{0}^{1}\left\vert \frac{d}{d\varepsilon }%
f\left( U_{\varepsilon }\right) d\varepsilon \right\vert \left\vert
w^{\prime }\right\vert dxds \\
\leq l_{1}\int_{0}^{t}\int_{\Omega }\int_{0}^{1}\left( \left\vert
U_{\varepsilon }\right\vert ^{\theta -1}+\left\vert k_{3}\left( x\right)
\right\vert \right) \left\vert u-v\right\vert \left\vert w^{\prime
}\right\vert d\varepsilon dxds \\
\leq C\int_{0}^{t}\int_{\Omega }\left( \left\vert u\right\vert ^{\theta
-1}+\left\vert v\right\vert ^{\theta -1}+\left\vert k_{3}\left( x\right)
\right\vert \right) \left\vert w\left( s\right) \right\vert \left\vert
w^{\prime }\left( s\right) \right\vert dxds=I.
\end{gather*}%
Using\ the generalized H\"{o}lder's, Young's inequalities, and the estimates
(\ref{27}), and choosing $\lambda $ such taht%
\begin{equation*}
\left\{
\begin{array}{l}
\lambda +1\leq \frac{n}{\left( \theta -1\right) \left( n-4\right) }\text{ if
}n\geq 5, \\
2\leq \lambda +1<\infty \text{ if }n=1,2,3,4,%
\end{array}%
\right.
\end{equation*}%
we infer%
\begin{gather}
I\leq C\int_{0}^{t}\left\Vert \left\vert u\right\vert ^{\theta
-1}+\left\vert v\right\vert ^{\theta -1}+\left\vert k_{3}\left( x\right)
\right\vert \right\Vert _{2\left( \lambda +1\right) }^{\lambda }\left\vert
\left\vert w\right\vert \right\vert _{2\left( \lambda +1\right) }\left\Vert
w^{\prime }\right\Vert _{2}  \notag \\
\leq C\int_{0}^{t}\left( \left\Vert \left\vert u\right\vert ^{\theta
-1}\right\Vert _{2\left( \lambda +1\right) }^{\lambda }+\left\Vert
\left\vert v\right\vert ^{\theta -1}\right\Vert _{2\left( \lambda +1\right)
}^{\lambda }+\left\Vert k_{3}\left( x\right) \right\Vert _{2\left( \lambda
+1\right) }^{\lambda }\right) \left\vert \left\vert w\right\vert \right\vert
_{2\left( \lambda +1\right) }\left\Vert w^{\prime }\right\Vert _{2}ds  \notag
\\
\leq C\int_{0}^{t}\left( \left\Vert \Delta u\right\Vert _{2}^{\lambda \left(
\theta -1\right) }+\left\Vert \Delta v\right\Vert _{2}^{\lambda \left(
\theta -1\right) }+\left\Vert k_{3}\left( x\right) \right\Vert _{\infty
}^{\lambda }\right) \left\vert \left\vert \Delta w\right\vert \right\vert
_{2}\left\Vert w^{\prime }\right\Vert _{2}ds  \notag \\
\leq C\int_{0}^{t}\left\vert \left\vert \Delta w\right\vert \right\vert
_{2}\left\Vert w^{\prime }\right\Vert _{2}ds\leq C\int_{0}^{t}\left(
\left\vert w^{\prime }(s)\right\vert ^{2}+\left\vert \Delta w\left( s\right)
\right\vert ^{2}\right) ds.  \label{35}
\end{gather}%
Combining (\ref{33}), (\ref{34}) and (\ref{35}) to obtain%
\begin{equation*}
\left\vert w^{\prime }(t)\right\vert ^{2}+\left\vert \Delta w\left( t\right)
\right\vert ^{2}\leq C\int_{0}^{t}\left( \left\vert w^{\prime
}(s)\right\vert ^{2}+\left\vert \Delta w\left( s\right) \right\vert
^{2}\right) ds.
\end{equation*}%
The integral inequality and Gronwall's lemma show that $w=0.$
\end{proof}

\section{Global existence}

In this section, we discuss the global existence of the solution for problem
(\ref{1}). In order to state and prove our main results, we first introduce the
following functions%
\begin{equation}
I\left( t\right) =I\left( u\left( t\right) \right) =\left\vert \Delta
u\left( t\right) \right\vert ^{2}-\beta \int_{\Omega }f\left( u\left(
t\right) \right) u\left( x,t\right) dx-\beta \int\limits_{\Omega
}k_{1}\left( x\right) \left\vert u\left( x,t\right) \right\vert dx,
\label{2g}
\end{equation}%
\begin{equation}
J\left( t\right) =J\left( u\left( t\right) \right) =\frac{1}{2}\left\vert
\Delta u\right\vert ^{2}-\beta \int_{\Omega }F\left( x,u\right) dx,
\label{3g}
\end{equation}%
\begin{equation}
E(t)=E(u(t),u^{\prime }(t))=J\left( u\left( t\right) \right) +\frac{1}{2}%
\left\vert u_{t}(t)\right\vert _{2}^{2}+\frac{1}{p}\left\Vert
u(t)\right\Vert _{p}^{p}.  \label{4g}
\end{equation}%
And the stable set as%
\begin{equation}
W=\left\{ u:u\in H_{0}^{2}\left( \Omega \right) \text{, }I\left( t\right)
>0\right\} \cup \left\{ 0\right\} .  \label{5g}
\end{equation}
The next lemma shows that our energy functional (\ref{4g}) is a
nonincreasing function along with the solution of (\ref{1}).

\begin{lemma}
\label{lemma1}$E(t)$ is a nonincreasing function for $t\geq 0$ and%
\begin{equation}
E^{\prime }\left( t\right) =-\left\vert \nabla u^{\prime }\left( t\right)
\right\vert ^{2}-\alpha \int_{\Omega }u^{\prime }\left( t\right) g\left(
u^{\prime }\left( t\right) \right) dx\leq 0.  \label{8g}
\end{equation}
\end{lemma}

\begin{proof}
By multiplying equation (\ref{1}) by $u^{\prime }$ and integrate over $%
\Omega $, using integrate by parts and summing up the product results,
\begin{equation*}
E\left( t\right) -E\left( 0\right) =-\int_{0}^{t}\left\vert \nabla u^{\prime
}\left( s\right) \right\vert ^{2}ds-\alpha \int_{0}^{t}\int_{\Omega
}u^{\prime }\left( s\right) g\left( u^{\prime }\left( s\right) \right) dxds%
\text{ for }t\geq 0.
\end{equation*}
\end{proof}

\begin{lemma}
Suppose that (\ref{H1})-(\ref{H4}) hold, let $u_{0}\in W$ and $u_{1}\in
H_{0}^{2}(\Omega )$ such that%
\begin{equation}
\gamma =\beta C_{\ast }^{\theta +1}\left( \frac{2p}{p-2}E\left( 0\right)
\right) ^{\frac{\theta -1}{2}}\left( l_{1}+l_{1}\left\vert \left\vert
k_{2}\left( x\right) \right\vert \right\vert _{\infty }+\left\vert
\left\vert k_{1}\left( x\right) \right\vert \right\vert _{\infty }\right) <1.
\label{9g}
\end{equation}%
Then $u\in W$ for each $t\geq 0.$
\end{lemma}
Where $C_{\ast }$ is the Sobolev--Poincar\'{e} embedding such that for all $%
2<p\leq \frac{2n}{n-4}\left( n\geq 5\right) $, $\left( 2\leq p<\infty \text{
if }n=1,2,3,4\right) $ we have%
\begin{equation*}
\left\Vert u\left( t\right) \right\Vert _{p}\leq C_{\ast }\left\Vert \Delta
u\left( t\right) \right\Vert _{2},\text{ }\forall u\in H_{0}^{2}(\Omega ).
\end{equation*}

\begin{proof}
Since $I\left( 0\right) >0$, by the continuity, there exists $0<T_{m}<T$
such
\begin{equation*}
I\left( t\right) \geq 0,\text{ }\forall t\in \left[ 0,T_{m}\right] ,
\end{equation*}%
this gives from (\ref{3g}), and (\ref{H3}),
\begin{gather}
E\left( t\right) \geq J\left( t\right) =\frac{1}{p}I\left( t\right) +\frac{%
p-2}{2p}\left\vert \Delta u\right\vert ^{2}  \notag \\
+\frac{\beta }{p}\left( \int_{\Omega }f\left( u\right) udx+\int_{\Omega
}k_{1}\left( x\right) \left\vert u\right\vert dx-p\int_{\Omega }F\left(
x,u\right) dx\right) \geq \frac{p-2}{2p}\left\vert \Delta u\right\vert ^{2}.
\label{10g}
\end{gather}%
By using (\ref{10g}), (\ref{4g}), and (\ref{8g}),
\begin{equation}
\left\vert \Delta u\right\vert ^{2}\leq \frac{2p}{p-2}J\left( t\right) \leq
\frac{2p}{p-2}E\left( t\right) \leq \frac{2p}{p-2}E\left( 0\right) .
\label{11g}
\end{equation}%
By recalling (\ref{H1}), (\ref{H2}), (\ref{11g}), (\ref{9g}),
Cauchy-Schwartz inequality, and Sobolev embedding we have%
\begin{gather}
\beta \int_{\Omega }f\left( u\right) udx+\beta \int_{\Omega }k_{1}\left(
x\right) \left\vert u\right\vert dx\leq \beta \int_{\Omega }\left\vert
f\left( u\right) \right\vert \left\vert u\right\vert dx+\beta \int_{\Omega
}\left\vert k_{1}\left( x\right) \right\vert \left\vert u\right\vert dx
\notag \\
\leq \beta l_{1}\int_{\Omega }\left\vert u\right\vert ^{\theta +1}dx+\beta
l_{1}\int_{\Omega }\left\vert k_{2}\left( x\right) \right\vert \left\vert
u\right\vert dx+\beta \int_{\Omega }\left\vert k_{1}\left( x\right)
\right\vert \left\vert u\right\vert dx  \notag \\
\leq \beta l_{1}\left\Vert u\left( t\right) \right\Vert _{\theta +1}^{\theta
+1}+\beta \left( l_{1}\left\vert \left\vert k_{2}\left( x\right) \right\vert
\right\vert _{\infty }+\left\vert \left\vert k_{1}\left( x\right)
\right\vert \right\vert _{\infty }\right) \left\Vert u\left( t\right)
\right\Vert _{\theta +1}^{\theta +1}  \notag \\
\leq \beta l_{1}C_{\ast }^{\theta +1}\left\vert \Delta u(t)\right\vert
^{\theta +1}+\beta C_{\ast }^{\theta +1}\left( l_{1}\left\vert \left\vert
k_{2}\left( x\right) \right\vert \right\vert _{\infty }+\left\vert
\left\vert k_{1}\left( x\right) \right\vert \right\vert _{\infty }\right)
\left\vert \Delta u(t)\right\vert ^{\theta +1}  \label{12g} \\
=\beta l_{1}C_{\ast }^{\theta +1}\left\vert \Delta u(t)\right\vert ^{\theta
-1}\left\vert \Delta u(t)\right\vert ^{2}  \notag \\
+\beta C_{\ast }^{\theta +1}\left( l_{1}\left\vert \left\vert k_{2}\left(
x\right) \right\vert \right\vert _{\infty }+\left\vert \left\vert
k_{1}\left( x\right) \right\vert \right\vert _{\infty }\right) \left\vert
\Delta u(t)\right\vert ^{\theta -1}\left\vert \Delta u(t)\right\vert ^{2}
\notag \\
\leq \beta C_{\ast }^{\theta +1}\left( \frac{2p}{p-2}E\left( 0\right)
\right) ^{\frac{\theta -1}{2}}\left( l_{1}+l_{1}\left\vert \left\vert
k_{2}\left( x\right) \right\vert \right\vert _{\infty }+\left\vert
\left\vert k_{1}\left( x\right) \right\vert \right\vert _{\infty }\right)
\left\vert \Delta u\right\vert ^{2}  \notag \\
<\left\vert \Delta u\right\vert ^{2}\text{ on }\left[ 0,T_{m}\right] .
\notag
\end{gather}%
Therefore, by using (\ref{2g}), we conclude that $I\left( t\right) >0\ $for
all $t\in \left[ 0,T_{m}\right] .$ By repeating this procedure, and using
the fact that
\begin{equation*}
\underset{t\rightarrow T_{m}}{\lim }\beta C_{\ast }^{\theta +1}\left( \frac{%
2p}{p-2}E\left( t\right) \right) ^{\frac{\theta -1}{2}}\left(
l_{1}+l_{1}\left\vert \left\vert k_{2}\left( x\right) \right\vert
\right\vert _{\infty }+\left\vert \left\vert k_{1}\left( x\right)
\right\vert \right\vert _{\infty }\right) \leq D<1,
\end{equation*}%
$T_{m}$ is extended to $T.$
\end{proof}

\begin{lemma}
Let the assumptions (\ref{9g}) holds. Then there exists $\eta =1-\gamma $
such that%
\begin{equation}
\beta \int_{\Omega }f\left( u\right) udx+\beta \int_{\Omega }k_{1}\left(
x\right) \left\vert u\right\vert dx\leq \left( 1-\eta \right) \left\vert
\Delta u\right\vert ^{2},  \label{13g}
\end{equation}%
and therefore%
\begin{equation}
\left\vert \Delta u\right\vert ^{2}\leq \frac{1}{\eta }I\left( t\right) .
\label{14g}
\end{equation}
\end{lemma}

\begin{proof}
From (\ref{12g}) we have
\begin{equation*}
\beta \int_{\Omega }f\left( u\right) udx+\beta \int_{\Omega }k_{1}\left(
x\right) \left\vert u\right\vert dx\leq \gamma \left\vert \Delta
u\right\vert ^{2}.
\end{equation*}%
We get (\ref{13g}) by\ taking $\eta =$ $1-\gamma >0,$ and by using (\ref{13g}%
), from (\ref{2g}) we get the result (\ref{14g}).
\end{proof}

\begin{theorem}
Suppose that (\ref{H1})-(\ref{H4}) hold. Let $u_{0}\in W$ satisfying (\ref%
{9g}). Then the solution of problem (\ref{1}) is global.
\end{theorem}

\begin{proof}
It sufficient to show that $\left\Vert u_{t}\right\Vert _{2}^{2}+\left\vert
\Delta u\right\vert ^{2}$ is bounded independently to $t.$ To see this we
use (\ref{2g}), (\ref{4g}), and (\ref{H3}) to obtain
\begin{gather*}
E(0)\geq E(t)=\frac{1}{2}\left\vert \Delta u\right\vert ^{2}-\beta
\int_{\Omega }F\left( x,u\right) dx+\frac{\text{ }1}{2}\left\Vert u^{\prime
}(t)\right\Vert _{2}^{2}+\frac{\text{ }1}{p}\left\Vert u(t)\right\Vert
_{p}^{p} \\
\geq \frac{1}{2}\left\vert \Delta u\right\vert ^{2}-\frac{\beta }{p}%
\int\limits_{\Omega }f\left( u\right) udx-\frac{\beta }{p}%
\int\limits_{\Omega }k_{1}\left( x\right) \left\vert u\right\vert dx \\
+\frac{\text{ }1}{2}\left\Vert u^{\prime }(t)\right\Vert _{2}^{2}+\frac{%
\text{ }1}{p}\left\Vert u(t)\right\Vert _{p}^{p}=\frac{1}{2}\left\vert
\Delta u\right\vert ^{2}+\frac{1}{p}\left( I\left( t\right) -\left\vert
\Delta u\right\vert ^{2}\right) + \\
+\frac{\text{ }1}{2}\left\Vert u^{\prime }(t)\right\Vert _{2}^{2}+\frac{%
\text{ }1}{p}\left\Vert u(t)\right\Vert _{p}^{p} \\
=\frac{p-2}{2p}\left\vert \Delta u\right\vert ^{2}+\frac{1}{p}I\left(
t\right) +\frac{\text{ }1}{2}\left\Vert u^{\prime }(t)\right\Vert _{2}^{2}+%
\frac{\text{ }1}{p}\left\Vert u(t)\right\Vert _{p}^{p} \\
\geq \frac{\text{ }1}{2}\left\Vert u^{\prime }(t)\right\Vert _{2}^{2}+\frac{%
p-2}{2p}\left\vert \Delta u\left( t\right) \right\vert ^{2},
\end{gather*}%
since $I\left( t\right) \geq 0,$ and $p>2$. Therefore%
\begin{equation*}
\left\Vert u^{\prime }(t)\right\Vert _{2}^{2}+\left\vert \Delta u\right\vert
^{2}\leq \max \left( 2,\frac{2p}{p-2}\right) E(0).
\end{equation*}%
These estimates imply that the solution $u(t)$ exist globally in $\left[
0,+\infty \right[ $.
\end{proof}

\section{Blow-up of Solution}

In this section, after some estimates, we show that the solution of problem (%
\ref{1}) blows up in finite time under the assumption $E(0)<0$, where
\begin{equation}
E(t)=E(u(t),u^{\prime }(t))=\frac{1}{2}\left\vert u^{\prime }\left( t\right)
\right\vert ^{2}+\frac{1}{2}\left\vert \Delta u\left( t\right) \right\vert
^{2}+\frac{1}{p}\left\Vert u(t)\right\Vert _{p}^{p}-\beta \int_{\Omega
}F\left( x,u\left( t\right) \right) dx.  \label{1s}
\end{equation}

\begin{remark}
We set
\begin{equation}
H\left( t\right) =-E\left( t\right) ,  \label{3s}
\end{equation}%
we multiply Eq.(\ref{1}) by $-u^{\prime }$ and integrate over $\Omega ,$
using (\ref{H2}) to get%
\begin{equation}
H^{\prime }\left( t\right) =\left\vert \nabla u^{\prime }\left( t\right)
\right\vert ^{2}+\alpha \int_{\Omega }u^{\prime }\left( t\right) g\left(
u^{\prime }\left( t\right) \right) dx\geq \alpha d_{0}\left\Vert u^{\prime
}\left( t\right) \right\Vert _{\sigma }^{\sigma }\text{ a.e. }t\in \left[ 0,T%
\right] ,  \label{5sb}
\end{equation}%
$H\left( t\right) $ is absolutely continuous, hence%
\begin{equation}
0<H\left( 0\right) \leq H\left( t\right) \leq \beta \int_{\Omega }F\left(
x,u\right) dx,  \label{6s}
\end{equation}%
when%
\begin{equation*}
E\left( 0\right) <0.
\end{equation*}
\end{remark}
We need the following lemma, easy to prove by using the definition of the
energy corresponding to the solution

\begin{lemma}
\label{Lemma1}Let $2<p\leq \frac{2n}{n-4}$ if $n\geq 5$ and $2<p<\infty $ if
$n\leq 4$. Then there exists a positive constant $C>1$, depending only on $%
\Omega $, such that%
\begin{equation}
\left\Vert u(t)\right\Vert _{p}^{s}\leq C\left( \left\Vert u(t)\right\Vert
_{p}^{p}+\left\vert \Delta u\left( t\right) \right\vert ^{2}\right) \text{,
with }2\leq s\leq p,  \label{2s}
\end{equation}%
for any $u\in H_{0}^{2}\left( \Omega \right) $. If $u$ is the solution
constructed in Theorem \ref{theorem1}, then%
\begin{equation}
\left\Vert u(t)\right\Vert _{p}^{s}\leq C\left( H\left( t\right) +\left\Vert
u(t)\right\Vert _{p}^{p}+\left\vert u^{\prime }\left( t\right) \right\vert
^{2}+\beta \int_{\Omega }F\left( x,u\left( t\right) \right) dx\right) ,
\label{4s}
\end{equation}%
with $2\leq s\leq p$ on $\left[ 0,T\right) .$
\end{lemma}

\begin{theorem}
Let the conditions of the Theorem \ref{theorem1} be satisfied. Assume
further that%
\begin{equation}
E\left( 0\right) <0.  \label{5s}
\end{equation}%
Then the solution (\ref{6b}) blows up in a finite time $T$.
\end{theorem}

\begin{proof}
We pose
\begin{equation*}
\left\{
\begin{array}{c}
L\left( t\right) =\left\vert u\left( t\right) \right\vert
^{2}=\int\limits_{\Omega }\left\vert u\left( x,t\right) \right\vert ^{2}dx,
\\
L^{\prime }\left( t\right) =2\left( u\left( t\right) ,u^{\prime }\left(
t\right) \right) , \\
L^{\prime \prime }\left( t\right) =2\left\vert u^{\prime }\left( t\right)
\right\vert ^{2}+2\left( u\left( t\right) ,u^{\prime \prime }\left( t\right)
\right) ,%
\end{array}%
\right.
\end{equation*}%
we define the function
\begin{gather}
G\left( t\right) =H^{1-a}\left( t\right) +\varepsilon L^{\prime }\left(
t\right) -3\varepsilon pe^{T-t}\beta \int_{\Omega }F\left( x,u\left(
t\right) \right) dx  \notag \\
+\gamma _{1}\varepsilon t\left\Vert k_{1}\left( x\right) \right\Vert
_{\infty }+\gamma _{2}\varepsilon t\left\Vert k_{2}\left( x\right)
\right\Vert _{\infty }^{\sigma },\text{ }t\geq 0,  \label{7s}
\end{gather}%
where $\gamma _{1},$ $\gamma _{2},$ $\varepsilon >0$ are positives constants
to be specified later, and%
\begin{equation}
0<a\leq \min \left( \frac{p-2}{2p},\frac{p-\sigma }{\left( \theta +1\right)
\left( \sigma -1\right) }\right) <1,  \label{8s}
\end{equation}%
derivative the Eq. (\ref{7s}), using Eq. (\ref{1}), and hypotheses (\ref{H3}%
) we obtain%
\begin{gather}
\frac{d}{dt}G\left( t\right) =\left( 1-a\right) H^{-a}\left( t\right)
H^{\prime }\left( t\right) +\varepsilon L^{\prime \prime }\left( t\right)
+\gamma _{1}\varepsilon \left\Vert k_{1}\left( x\right) \right\Vert _{\infty
}  \notag \\
+\gamma _{2}\varepsilon \left\Vert k_{2}\left( x\right) \right\Vert _{\infty
}^{\sigma }+\frac{d}{dt}\left( -3p\varepsilon e^{T-t}\beta \int_{\Omega
}F\left( x,u\left( t\right) \right) dx\right)  \notag \\
=\left( 1-a\right) H^{-a}\left( t\right) H^{\prime }\left( t\right)
+2\varepsilon \left\vert u^{\prime }\left( t\right) \right\vert
^{2}+2\varepsilon \left( u\left( t\right) ,u^{\prime \prime }\left( t\right)
\right)  \notag \\
+\gamma _{1}\varepsilon \left\Vert k_{1}\left( x\right) \right\Vert _{\infty
}+\gamma _{2}\varepsilon \left\Vert k_{2}\left( x\right) \right\Vert
_{\infty }^{\sigma }+  \notag \\
+3p\varepsilon e^{T-t}\beta \int_{\Omega }F\left( x,u\left( t\right) \right)
dx-3p\varepsilon e^{T-t}\beta \int_{\Omega }f\left( u\left( t\right) \right)
u^{\prime }\left( t\right) dx  \label{9s} \\
=\left( 1-a\right) H^{-a}\left( t\right) H^{\prime }\left( t\right)
+2\varepsilon \left\vert u^{\prime }\left( t\right) \right\vert ^{2}+2\beta
\varepsilon \int_{\Omega }u\left( t\right) f\left( u\left( t\right) \right)
dx  \notag \\
-2\varepsilon \left\vert \Delta u\left( t\right) \right\vert
^{2}-2\varepsilon \int_{\Omega }u\left( t\right) \Delta u^{\prime }\left(
t\right) dx-2\varepsilon \left\Vert u\left( t\right) \right\Vert _{p}^{p}
\notag \\
+\gamma _{1}\varepsilon \left\Vert k_{1}\left( x\right) \right\Vert _{\infty
}+\gamma _{2}\varepsilon \left\Vert k_{2}\left( x\right) \right\Vert
_{\infty }^{\sigma }  \notag \\
+3p\varepsilon e^{T-t}\beta \int_{\Omega }F\left( x,u\left( t\right) \right)
dx-3p\varepsilon e^{T-t}\beta \int_{\Omega }f\left( u\left( t\right) \right)
u^{\prime }\left( t\right) dx  \notag \\
-2\alpha \varepsilon \int_{\Omega }u\left( t\right) g\left( u^{\prime
}\left( t\right) \right) dx.  \notag
\end{gather}%
We then exploit Holder's, Young's inequalities, and the hypotheses on $g$,
to estimate the last term in (\ref{9s}) as%
\begin{gather}
2\alpha \varepsilon \left\vert \int_{\Omega }u\left( t\right) g\left(
u^{\prime }\left( t\right) \right) dx\right\vert \leq 2\alpha \varepsilon
d_{1}\int_{\Omega }\left\vert u^{\prime }\left( t\right) \right\vert
\left\vert u\left( t\right) \right\vert dx+2\alpha \varepsilon
d_{2}\int_{\Omega }\left\vert u^{\prime }\left( t\right) \right\vert
^{\sigma -1}\left\vert u\left( t\right) \right\vert dx  \notag \\
\leq 2\alpha \varepsilon d_{1}\frac{\delta ^{\sigma }}{\sigma }\left\vert
\left\vert u\left( t\right) \right\vert \right\vert _{\sigma }^{\sigma
}+2\alpha \varepsilon d_{1}\frac{\sigma -1}{\sigma }\delta ^{\frac{\sigma }{%
1-\sigma }}\left\vert \left\vert u^{\prime }\left( t\right) \right\vert
\right\vert _{\frac{\sigma }{\sigma -1}}^{\frac{\sigma }{\sigma -1}}
\label{10s} \\
+2\alpha \varepsilon d_{2}\frac{\delta ^{\sigma }}{\sigma }\left\vert
\left\vert u\left( t\right) \right\vert \right\vert _{\sigma }^{\sigma
}+2\alpha \varepsilon d_{2}\frac{\sigma -1}{\sigma }\delta ^{\frac{\sigma }{%
1-\sigma }}\left\vert \left\vert u^{\prime }\left( t\right) \right\vert
\right\vert _{\sigma }^{\sigma }  \notag \\
=2\left( d_{1}+d_{2}\right) \frac{\delta ^{\sigma }}{\sigma }\alpha
\varepsilon \left\vert \left\vert u\left( t\right) \right\vert \right\vert
_{\sigma }^{\sigma }  \notag \\
+2\alpha \varepsilon \frac{\sigma -1}{\sigma }\delta ^{\frac{\sigma }{%
1-\sigma }}\left( d_{1}\left\vert \left\vert u^{\prime }\left( t\right)
\right\vert \right\vert _{\frac{\sigma }{\sigma -1}}^{\frac{\sigma }{\sigma
-1}}+d_{2}\left\vert \left\vert u^{\prime }\left( t\right) \right\vert
\right\vert _{\sigma }^{\sigma }\right) ,\text{ }\delta >0,  \notag
\end{gather}%
because $\frac{\sigma }{\sigma -1}\leq \sigma ,$ then by (\ref{5sb}) we have
\begin{eqnarray}
&&d_{1}\left\vert \left\vert u^{\prime }\left( t\right) \right\vert
\right\vert _{\frac{\sigma }{\sigma -1}}^{\frac{\sigma }{\sigma -1}%
}+d_{2}\left\vert \left\vert u^{\prime }\left( t\right) \right\vert
\right\vert _{\sigma }^{\sigma }\leq C\left( \Omega \right) ^{\frac{\sigma -2%
}{\sigma }}d_{1}\left\vert \left\vert u^{\prime }\left( t\right) \right\vert
\right\vert _{\sigma }^{\frac{\sigma }{\sigma -1}}+\frac{d_{2}}{\alpha d_{0}}%
H^{\prime }\left( t\right)  \notag \\
&\leq &C^{\ast }d_{1}C\left( \Omega \right) ^{\frac{\sigma -2}{\sigma }%
}\left\vert \left\vert u^{\prime }\left( t\right) \right\vert \right\vert
_{\sigma }^{\sigma }+\frac{d_{2}}{\alpha d_{0}}H^{\prime }\left( t\right)
\leq \frac{1}{\alpha d_{0}}\left( C^{\ast }d_{1}C\left( \Omega \right) ^{%
\frac{\sigma -2}{\sigma }}+d_{2}\right) H^{\prime }\left( t\right) .
\label{10sb}
\end{eqnarray}%
By the boundary conditions we derive the following estimates
\begin{equation}
\int_{\Omega }u\left( t\right) \Delta u^{\prime }\left( t\right)
dx=\int_{\Omega }\Delta u\left( t\right) u^{\prime }\left( t\right) dx\leq
\frac{1}{4}\left\vert \Delta u\left( t\right) \right\vert ^{2}+\left\vert
u^{\prime }\left( t\right) \right\vert ^{2}.  \label{11sb}
\end{equation}%
Using hypotheses (\ref{H4}), Holder's, Young's inequalities, conditions (\ref%
{8s}), and (\ref{5sb}) we have
\begin{gather*}
\int\limits_{\Omega }\left\vert f\left( u\left( t\right) \right) \right\vert
\left\vert u^{\prime }\left( t\right) \right\vert dx\leq
l_{1}\int\limits_{\Omega }\left( \left\vert u\right\vert ^{\theta
}\left\vert u^{\prime }\left( t\right) \right\vert +\left\vert k_{2}\left(
x\right) \right\vert \left\vert u^{\prime }\left( t\right) \right\vert
\right) dx \\
\leq l_{1}\left\vert \left\vert u\left( t\right) \right\vert \right\vert
_{2\theta }^{\theta }\left\vert \left\vert u^{\prime }\left( t\right)
\right\vert \right\vert _{2} \\
+l_{1}\frac{\sigma -1}{\sigma }\delta ^{\frac{\sigma }{1-\sigma }}\left\vert
\left\vert u^{\prime }\left( t\right) \right\vert \right\vert _{\frac{\sigma
}{\sigma -1}}^{\frac{\sigma }{\sigma -1}}+l_{1}\frac{\delta ^{\sigma }}{%
\sigma }\left\Vert k_{2}\left( x\right) \right\Vert _{\infty }^{\sigma } \\
\leq \frac{l_{1}}{\sigma }C\left( \delta ,\sigma \right) \delta ^{\sigma
}\left\vert \left\vert u\left( t\right) \right\vert \right\vert _{2\theta
}^{2\theta }+\frac{1}{\sigma }l_{1}\delta ^{\frac{\sigma }{1-\sigma }%
}\left\vert \left\vert u^{\prime }\left( t\right) \right\vert \right\vert
_{2}^{2} \\
+l_{1}\frac{\sigma -1}{\sigma }\delta ^{\frac{\sigma }{1-\sigma }}\left\vert
\left\vert u^{\prime }\left( t\right) \right\vert \right\vert _{\frac{\sigma
}{\sigma -1}}^{\frac{\sigma }{\sigma -1}}+l_{1}\frac{\delta ^{\sigma }}{%
\sigma }\left\Vert k_{2}\left( x\right) \right\Vert _{\infty }^{\sigma } \\
\leq \frac{l_{1}}{\sigma }C^{\ast }C\left( \delta ,\sigma \right) C\left(
\Omega \right) ^{\frac{\sigma -2\theta }{2\theta \sigma }}\left\vert
\left\vert u\right\vert \right\vert _{\sigma }^{\sigma } \\
+\frac{1}{\sigma }l_{1}C^{\ast }C\left( \Omega \right) ^{\frac{\sigma -2}{%
2\sigma }}\delta ^{\frac{\sigma }{1-\sigma }}\left\vert \left\vert u^{\prime
}\left( t\right) \right\vert \right\vert _{\sigma }^{\sigma } \\
+l_{1}\frac{\sigma -1}{\sigma }\delta ^{\frac{\sigma }{1-\sigma }}C^{\ast
}C\left( \Omega \right) ^{\frac{\sigma -2}{2\sigma }}\left\vert \left\vert
u^{\prime }\left( t\right) \right\vert \right\vert _{\sigma }^{\sigma }+l_{1}%
\frac{\delta ^{\sigma }}{\sigma }\left\Vert k_{2}\left( x\right) \right\Vert
_{\infty }^{\sigma } \\
\leq \frac{l_{1}}{\alpha d_{0}}C^{\ast }C\left( \Omega \right) ^{\frac{%
\sigma -2}{2\sigma }}\delta ^{\frac{\sigma }{1-\sigma }}H^{\prime }\left(
t\right) \\
+\frac{l_{1}}{\sigma }C\left( \delta ,\sigma \right) \delta ^{\sigma
}C^{\ast }C\left( \Omega \right) ^{\frac{\sigma -2\theta }{2\theta \sigma }%
}\left\vert \left\vert u\right\vert \right\vert _{\sigma }^{\sigma }+l_{1}%
\frac{\delta ^{\sigma }}{\sigma }\left\Vert k_{2}\left( x\right) \right\Vert
_{\infty }^{\sigma }.
\end{gather*}%
By the hypotheses (\ref{H3}), and the estimate (\ref{6s}) we have%
\begin{eqnarray}
2\beta \int\limits_{\Omega }u\left( t\right) f\left( u\left( t\right)
\right) dx &\geq &2\beta p\int\limits_{\Omega }F\left( x\right) dx-2\beta
\int\limits_{\Omega }k_{1}\left( x\right) \left\vert u\left( x\right)
\right\vert dx  \notag \\
&\geq &2pH\left( t\right) -2\beta \int\limits_{\Omega }k_{1}\left( x\right)
\left\vert u\left( x\right) \right\vert dx,  \label{12s}
\end{eqnarray}%
and by Holder's, Young's inequalities,
\begin{equation}
\int\limits_{\Omega }k_{1}\left( x\right) \left\vert u\left( x\right)
\right\vert dx\leq C\left( \sigma ,\alpha \right) \left\Vert k_{1}\left(
x\right) \right\Vert _{\infty }+2\alpha \frac{\delta ^{\sigma }}{\sigma }%
\left\vert \left\vert u\left( t\right) \right\vert \right\vert _{\sigma
}^{\sigma }.  \label{12bs}
\end{equation}%
By substituting in (\ref{9s}), and using (\ref{10s})-(\ref{12bs}), yields,
\begin{gather}
\frac{d}{dt}G\left( t\right)  \notag \\
\geq \left(
\begin{array}{c}
\left( 1-a\right) H^{-a}\left( t\right) \\
-\frac{1}{\alpha d_{0}}\left( 3p\varepsilon e^{T-t}\beta C^{\ast }C\left(
\Omega \right) ^{\frac{\sigma -2}{2\sigma }}+2\alpha \varepsilon \frac{%
\sigma -1}{\sigma }\left( C^{\ast }d_{1}C\left( \Omega \right) ^{\frac{%
\sigma -2}{\sigma }}+d_{2}\right) \right) \delta ^{\frac{\sigma }{1-\sigma }}%
\end{array}%
\right) H^{\prime }\left( t\right)  \notag \\
+2p\varepsilon H\left( t\right) -2\varepsilon \left\Vert u\left( t\right)
\right\Vert _{p}^{p}-\frac{5}{2}\varepsilon \left\vert \Delta u\left(
t\right) \right\vert ^{2}+\left( \gamma _{1}-2\beta C\left( \sigma ,\alpha
\right) \right) \varepsilon \left\Vert k_{1}\left( x\right) \right\Vert
_{\infty }  \notag \\
+\left( \gamma _{2}-3p\varepsilon e^{T-t}\beta l_{1}\frac{\delta ^{\sigma }}{%
\sigma }\right) \varepsilon \left\Vert k_{2}\left( x\right) \right\Vert
_{\infty }^{\sigma }+3p\beta \varepsilon \int\limits_{\Omega }F\left(
x,u\left( s\right) \right) dx  \notag \\
-\varepsilon \left( 3\theta pe^{T-t}\beta l_{1}C\left( \delta ,\sigma
\right) C^{\ast }C\left( \Omega \right) ^{\frac{\sigma -2\theta }{2\theta
\sigma }}+2\beta \alpha \left( d_{1}+d_{2}\right) \right) \frac{\delta
^{\sigma }}{\sigma }\left\vert \left\vert u\left( t\right) \right\vert
\right\vert _{\sigma }^{\sigma },\text{ }\forall \delta ,\text{ }\varepsilon
>0.  \label{13s}
\end{gather}%
At this point, for a large positive constant $\lambda $ to be chosen later,
picking $\delta $ such that $\delta ^{\frac{\sigma }{1-\sigma }}=\lambda
H^{-a}\left( t\right) >0$ in (\ref{13s}) we arrive for all $t>0$ at%
\begin{gather}
\frac{d}{dt}G\left( t\right)  \notag \\
\geq \left(
\begin{array}{c}
\left( 1-a\right) \\
-\frac{\lambda }{\alpha d_{0}}\left( 3p\varepsilon e^{T}\beta C^{\ast
}C\left( \Omega \right) ^{\frac{\sigma -2}{2\sigma }}+2\alpha \varepsilon
\frac{\sigma -1}{\sigma }\left( C^{\ast }d_{1}C\left( \Omega \right) ^{\frac{%
\sigma -2}{\sigma }}+d_{2}\right) \right)%
\end{array}%
\right) H^{-a}\left( t\right) H^{\prime }\left( t\right)  \notag \\
+3\beta p\varepsilon \int_{\Omega }F\left( x,u\right) dx-2\varepsilon
\left\Vert u\left( t\right) \right\Vert _{p}^{p}-\frac{5}{2}\varepsilon
\left\vert \Delta u\left( t\right) \right\vert ^{2}+2p\varepsilon H\left(
t\right)  \notag \\
+\left( \gamma _{1}-2\beta C\left( \sigma ,\alpha \right) \right)
\varepsilon \left\Vert k_{1}\left( x\right) \right\Vert _{\infty }
\label{14s} \\
+\left( \gamma _{2}-3p\varepsilon e^{T}\beta l_{1}\frac{\delta ^{\sigma }}{%
\sigma }\right) \varepsilon \left\Vert k_{2}\left( x\right) \right\Vert
_{\infty }^{\sigma }  \notag \\
-\varepsilon \left( 3\theta pe^{T}\beta l_{1}C\left( \delta ,\sigma \right)
C^{\ast }C\left( \Omega \right) ^{\frac{\sigma -2\theta }{2\theta \sigma }%
}+2\beta \alpha \left( d_{1}+d_{2}\right) \right) \frac{\lambda ^{1-\sigma }%
}{\sigma }H^{a\left( \sigma -1\right) }\left( t\right) \left\vert \left\vert
u\left( t\right) \right\vert \right\vert _{\sigma }^{\sigma },\text{ }%
\forall \delta ,\text{ }\varepsilon >0.  \notag
\end{gather}%
By exploiting (\ref{6s}), we have%
\begin{equation}
H^{a\left( \sigma -1\right) }\left( t\right) \left\vert \left\vert u\left(
t\right) \right\vert \right\vert _{\sigma }^{\sigma }\leq \beta ^{a\left(
\sigma -1\right) }\left( \int\limits_{\Omega }F\left( x,u\right) dx\right)
^{a\left( \sigma -1\right) }\left\vert \left\vert u\left( t\right)
\right\vert \right\vert _{\sigma }^{\sigma },  \label{15s}
\end{equation}%
from (\ref{H3}) we have%
\begin{gather}
\int_{\Omega }F\left( x,u\right) dx\leq \frac{l_{1}}{p}\left(
\int\limits_{\Omega }\left\vert u\left( t\right) \right\vert ^{\theta
+1}dx+\left( \left\vert k_{2}\left( x\right) \right\vert +\left\vert
k_{1}\left( x\right) \right\vert \right) \left\vert u\right\vert \right)
\notag \\
\leq \frac{l_{1}}{p}\left\vert \left\vert u\left( t\right) \right\vert
\right\vert _{\theta +1}^{\theta +1}+C\frac{l_{1}}{p}\left( \left\Vert
k_{1}\left( x\right) \right\Vert _{\infty }+\left\Vert k_{2}\left( x\right)
\right\Vert _{\infty }\right) \left\vert \left\vert u\left( t\right)
\right\vert \right\vert _{\theta +1}^{\theta +1},  \notag \\
\leq C\frac{l_{1}}{p}\left\vert \left\vert u\left( t\right) \right\vert
\right\vert _{\theta +1}^{\theta +1}  \label{16s}
\end{gather}%
by condition (\ref{8s}), and the estimates (\ref{4s}) we confirm that%
\begin{gather}
\beta ^{a\left( \sigma -1\right) }\left\vert \int\limits_{\Omega }F\left(
x,u\right) dx\right\vert ^{a\left( \sigma -1\right) }\left\vert \left\vert
u\left( t\right) \right\vert \right\vert _{\sigma }^{\sigma }\leq  \notag \\
\leq C\frac{l_{1}}{p}\beta ^{a\left( \sigma -1\right) }\left( \left\vert
\left\vert u\left( t\right) \right\vert \right\vert _{\theta +1}^{\theta
+1}\right) ^{a\left( \sigma -1\right) }\left\vert \left\vert u\left(
t\right) \right\vert \right\vert _{\sigma }^{\sigma }  \notag \\
=C\frac{l_{1}}{p}\beta ^{a\left( \sigma -1\right) }\left\vert \left\vert
u\left( t\right) \right\vert \right\vert _{\theta +1}^{\left( \theta
+1\right) a\left( \sigma -1\right) }\left\vert \left\vert u\left( t\right)
\right\vert \right\vert _{\sigma }^{\sigma }  \notag \\
\leq C\frac{l_{1}}{p}\beta ^{a\left( \sigma -1\right) }\left\vert \left\vert
u\left( t\right) \right\vert \right\vert _{\theta +1}^{\left( \theta
+1\right) a\left( \sigma -1\right) }\left\vert \left\vert u\left( t\right)
\right\vert \right\vert _{\theta +1}^{\sigma }  \notag \\
=C\frac{l_{1}}{p}\beta ^{a\left( \sigma -1\right) }\left\vert \left\vert
u\left( t\right) \right\vert \right\vert _{\theta +1}^{\left( \theta
+1\right) a\left( \sigma -1\right) +\sigma }  \notag \\
\leq \frac{l_{1}}{p}\beta ^{a\left( \sigma -1\right) }C\left( H\left(
t\right) +\left\Vert u(t)\right\Vert _{p}^{p}+\left\vert u^{\prime
}(t)\right\vert ^{2}+\beta \int\limits_{\Omega }F\left( x,u\right) dx\right)
\notag \\
\leq C\frac{l_{1}}{p}\beta ^{a\left( \sigma -1\right) }\left(
\begin{array}{c}
H\left( t\right) +\left\Vert u(t)\right\Vert _{p}^{p}+\left\vert u^{\prime
}(t)\right\vert ^{2}+\beta \int\limits_{\Omega }F\left( x,u\right) dx \\
+\left\Vert k_{1}\left( x\right) \right\Vert _{\infty }+\left\Vert
k_{2}\left( x\right) \right\Vert _{\infty }^{\sigma }%
\end{array}%
\right)  \label{17s}
\end{gather}%
substituting (\ref{17s}) in (\ref{14s}) we obtain
\begin{gather}
\frac{d}{dt}G\left( t\right)  \notag \\
\geq \left( \left( 1-a\right) -\frac{\lambda }{\alpha d_{0}}\left(
\begin{array}{c}
3p\varepsilon e^{T}\beta C^{\ast }C\left( \Omega \right) ^{\frac{\sigma -2}{%
2\sigma }} \\
+2\alpha \varepsilon \frac{\sigma -1}{\sigma }\left( C^{\ast }d_{1}C\left(
\Omega \right) ^{\frac{\sigma -2}{\sigma }}+d_{2}\right)%
\end{array}%
\right) \right)  \notag \\
\times H^{-a}\left( t\right) H^{\prime }\left( t\right)  \notag \\
+3p\beta \varepsilon \int\limits_{\Omega }F\left( x,u\right) dx-\frac{5}{2}%
\varepsilon \left\vert \Delta u\left( t\right) \right\vert ^{2}-2\varepsilon
\left\Vert u\left( t\right) \right\Vert _{p}^{p}  \notag \\
+\varepsilon \left( \gamma _{1}-2\beta C\left( \sigma ,\alpha \right)
\right) \left\Vert k_{1}\left( x\right) \right\Vert _{\infty }  \notag \\
+\varepsilon \left( \gamma _{2}-3p\varepsilon e^{T}\beta l_{1}\frac{\delta
^{\sigma }}{\sigma }\right) \left\Vert k_{2}\left( x\right) \right\Vert
_{\infty }^{\sigma }  \label{20s} \\
+\varepsilon \left(
\begin{array}{c}
2pH\left( t\right) -\left(
\begin{array}{c}
3\theta pe^{T}\beta l_{1}C\left( \delta ,\sigma \right) C^{\ast }C\left(
\Omega \right) ^{\frac{\sigma -2\theta }{2\theta \sigma }} \\
+2\beta \alpha \left( d_{1}+d_{2}\right)%
\end{array}%
\right) \frac{\lambda ^{1-\sigma }}{\sigma }\frac{l_{1}}{p}\beta ^{a\left(
\sigma -1\right) } \\
\times C\left(
\begin{array}{c}
H\left( t\right) +\left\Vert u(t)\right\Vert _{p}^{p}+\left\vert u^{\prime
}(t)\right\vert ^{2}+\beta \int\limits_{\Omega }F\left( x,u\right) dx \\
+\left\Vert k_{1}\left( x\right) \right\Vert _{\infty }+\left\Vert
k_{2}\left( x\right) \right\Vert _{\infty }^{\sigma }%
\end{array}%
\right)%
\end{array}%
\right)  \notag
\end{gather}%
or
\begin{gather}
\frac{d}{dt}G\left( t\right)  \notag \\
\geq \left(
\begin{array}{c}
\left( 1-a\right) \\
-\frac{\lambda }{\alpha d_{0}}\left(
\begin{array}{c}
3p\varepsilon e^{T}\beta C^{\ast }C\left( \Omega \right) ^{\frac{\sigma -2}{%
2\sigma }} \\
+2\alpha \varepsilon \frac{\sigma -1}{\sigma }\left( C^{\ast }d_{1}C\left(
\Omega \right) ^{\frac{\sigma -2}{\sigma }}+d_{2}\right)%
\end{array}%
\right)%
\end{array}%
\right) H^{-a}\left( t\right) H^{\prime }\left( t\right)  \notag \\
+3p\beta \varepsilon \int_{\Omega }F\left( x,u\right) dx-\frac{5}{2}%
\varepsilon \left\vert \Delta u\left( t\right) \right\vert ^{2}-2\varepsilon
\left\Vert u\left( t\right) \right\Vert _{p}^{p}  \notag \\
+\varepsilon \left( \gamma _{1}-2\beta C\left( \sigma ,\alpha \right)
\right) \left\Vert k_{1}\left( x\right) \right\Vert _{\infty }  \label{21s}
\\
+\varepsilon \left( \gamma _{2}-3p\varepsilon e^{T}\beta l_{1}\frac{\delta
^{\sigma }}{\sigma }\right) \left\Vert k_{2}\left( x\right) \right\Vert
_{\infty }^{\sigma }  \notag \\
+\varepsilon \left(
\begin{array}{c}
\left( 5p-1\right) H\left( t\right) \\
-\left(
\begin{array}{c}
3\theta pe^{T-t}\beta l_{1}C\left( \delta ,\sigma \right) C^{\ast }C\left(
\Omega \right) ^{\frac{\sigma -2\theta }{2\theta \sigma }} \\
+2\beta \alpha \left( d_{1}+d_{2}\right)%
\end{array}%
\right) \frac{\lambda ^{1-\sigma }}{\sigma }\frac{l_{1}}{p}\beta ^{a\left(
\sigma -1\right) } \\
\times C\left(
\begin{array}{c}
H\left( t\right) +\left\Vert u(t)\right\Vert _{p}^{p}+\left\vert u^{\prime
}(t)\right\vert ^{2}+\beta \int_{\Omega }F\left( x,u\right) dx \\
+\left\Vert k_{1}\left( x\right) \right\Vert _{\infty }+\left\Vert
k_{2}\left( x\right) \right\Vert _{\infty }^{\sigma }%
\end{array}%
\right)%
\end{array}%
\right)  \notag \\
-\varepsilon \left( 3p-1\right) H\left( t\right) .  \notag
\end{gather}%
By using the definition (\ref{3s}), the estimate (\ref{21s}) gives%
\begin{gather*}
\frac{d}{dt}G\left( t\right) \\
\geq \left(
\begin{array}{c}
\left( 1-a\right) \\
-\frac{\lambda }{\alpha d_{0}}\left(
\begin{array}{c}
3p\varepsilon e^{T}\beta C^{\ast }C\left( \Omega \right) ^{\frac{\sigma -2}{%
2\sigma }} \\
+2\alpha \varepsilon \frac{\sigma -1}{\sigma }\left( C^{\ast }d_{1}C\left(
\Omega \right) ^{\frac{\sigma -2}{\sigma }}+d_{2}\right)%
\end{array}%
\right)%
\end{array}%
\right) \\
\times H^{-a}\left( t\right) H^{\prime }\left( t\right)
\end{gather*}%
\begin{gather*}
+\varepsilon \left[
\begin{array}{c}
\left( \frac{3p-1}{2}\right) \\
-\left( C\left(
\begin{array}{c}
3\theta pe^{T}\beta l_{1}C\left( \delta ,\sigma \right) C^{\ast }C\left(
\Omega \right) ^{\frac{\sigma -2\theta }{2\theta \sigma }} \\
+2\beta \alpha \left( d_{1}+d_{2}\right)%
\end{array}%
\right) \frac{\lambda ^{1-\sigma }}{\sigma }\frac{l_{1}}{p}\beta ^{a\left(
\sigma -1\right) }\right)%
\end{array}%
\right] \\
\times \left\vert u^{\prime }\left( t\right) \right\vert ^{2}
\end{gather*}%
\begin{gather*}
+\left( \frac{3p-1}{2}-\frac{5}{2}\right) \varepsilon \left\vert \Delta
u\left( t\right) \right\vert ^{2} \\
+\varepsilon \left[
\begin{array}{c}
\left( \gamma _{1}-2\beta C\left( \sigma ,\alpha \right) \right) \\
-C\left( \left(
\begin{array}{c}
3\theta pe^{T}\beta l_{1}C\left( \delta ,\sigma \right) C^{\ast }C\left(
\Omega \right) ^{\frac{\sigma -2\theta }{2\theta \sigma }} \\
+2\beta \alpha \left( d_{1}+d_{2}\right)%
\end{array}%
\right) \frac{\lambda ^{1-\sigma }}{\sigma }\frac{l_{1}}{p}\beta ^{a\left(
\sigma -1\right) }\right)%
\end{array}%
\right] \left\Vert k_{1}\left( x\right) \right\Vert _{\infty }
\end{gather*}%
\begin{equation*}
+\varepsilon \left[
\begin{array}{c}
\left( \gamma _{2}-3p\varepsilon e^{T}\beta l_{1}\frac{\delta ^{\sigma }}{%
\sigma }\right) \\
-C\left( \left(
\begin{array}{c}
3\theta pe^{T}\beta l_{1}C\left( \delta ,\sigma \right) C^{\ast }C\left(
\Omega \right) ^{\frac{\sigma -2\theta }{2\theta \sigma }} \\
+2\beta \alpha \left( d_{1}+d_{2}\right)%
\end{array}%
\right) \frac{\lambda ^{1-\sigma }}{\sigma }\frac{l_{1}}{p}\beta ^{a\left(
\sigma -1\right) }\right)%
\end{array}%
\right] \left\Vert k_{2}\left( x\right) \right\Vert _{\infty }^{\sigma }
\end{equation*}%
\begin{gather*}
+\varepsilon \left[
\begin{array}{c}
\left( \frac{3p-1}{p}-2\right) \\
-C\left( \left(
\begin{array}{c}
3\theta pe^{T}\beta l_{1}C\left( \delta ,\sigma \right) C^{\ast }C\left(
\Omega \right) ^{\frac{\sigma -2\theta }{2\theta \sigma }} \\
+2\beta \alpha \left( d_{1}+d_{2}\right)%
\end{array}%
\right) \frac{\lambda ^{1-\sigma }}{\sigma }\frac{l_{1}}{p}\beta ^{a\left(
\sigma -1\right) }\right)%
\end{array}%
\right] \\
\times \left\Vert u\left( t\right) \right\Vert _{p}^{p}
\end{gather*}%
\begin{equation*}
+\varepsilon \left[
\begin{array}{c}
3p-\left( 3p-1\right) \\
-C\left( \left(
\begin{array}{c}
3\theta pe^{T}\beta l_{1}C\left( \delta ,\sigma \right) C^{\ast }C\left(
\Omega \right) ^{\frac{\sigma -2\theta }{2\theta \sigma }} \\
+2\beta \alpha \left( d_{1}+d_{2}\right)%
\end{array}%
\right) \frac{\lambda ^{1-\sigma }}{\sigma }\frac{l_{1}}{p}\beta ^{a\left(
\sigma -1\right) }\right)%
\end{array}%
\right] \beta \int\limits_{\Omega }F\left( x,u\right) dx
\end{equation*}%
\begin{equation*}
+\varepsilon \left[
\begin{array}{c}
\left( 5p-1\right) \\
-C\left( \left(
\begin{array}{c}
3\theta pe^{T}\beta l_{1}C\left( \delta ,\sigma \right) C^{\ast }C\left(
\Omega \right) ^{\frac{\sigma -2\theta }{2\theta \sigma }} \\
+2\beta \alpha \left( d_{1}+d_{2}\right)%
\end{array}%
\right) \frac{\lambda ^{1-\sigma }}{\sigma }\frac{l_{1}}{p}\beta ^{a\left(
\sigma -1\right) }\right)%
\end{array}%
\right] H\left( t\right) .
\end{equation*}%
pose%
\begin{equation*}
C_{1}=C\left( \left(
\begin{array}{c}
3\theta pe^{T}\beta l_{1}C\left( \delta ,\sigma \right) C^{\ast }C\left(
\Omega \right) ^{\frac{\sigma -2\theta }{2\theta \sigma }} \\
+2\beta \alpha \left( d_{1}+d_{2}\right)%
\end{array}%
\right) \frac{1}{\sigma }\frac{l_{1}}{p}\beta ^{a\left( \sigma -1\right)
}\right) ,
\end{equation*}%
we arrive at%
\begin{gather}
\frac{d}{dt}G\left( t\right)  \notag \\
\geq \left(
\begin{array}{c}
\left( 1-a\right) \\
-\frac{\lambda }{\alpha d_{0}}\varepsilon \left(
\begin{array}{c}
3pe^{T}\beta C^{\ast }C\left( \Omega \right) ^{\frac{\sigma -2}{2\sigma }}
\\
+2\frac{\sigma -1}{\sigma }\left( C^{\ast }d_{1}C\left( \Omega \right) ^{%
\frac{\sigma -2}{\sigma }}+d_{2}\right)%
\end{array}%
\right)%
\end{array}%
\right) H^{-a}\left( t\right) H^{\prime }\left( t\right)  \notag \\
+\varepsilon \left[ \frac{3p-1}{2}-C_{1}\lambda ^{1-\sigma }\right]
\left\vert u^{\prime }\left( t\right) \right\vert ^{2}+\left( \frac{3p-1}{2}-%
\frac{5}{2}\right) \varepsilon \left\vert \Delta u\left( t\right)
\right\vert ^{2}  \notag \\
+\varepsilon \left( \left( \gamma _{1}-2\beta C\left( \sigma ,\alpha \right)
\right) -C_{1}\lambda ^{1-\sigma }\right) \left\Vert k_{1}\left( x\right)
\right\Vert _{\infty }  \notag \\
+\varepsilon \left( \left( \gamma _{2}-3p\varepsilon e^{T}\beta l_{1}\frac{%
\delta ^{\sigma }}{\sigma }\right) -C_{1}\lambda ^{1-\sigma }\right)
\left\Vert k_{2}\left( x\right) \right\Vert _{\infty }^{\sigma }  \notag \\
+\varepsilon \left[ \frac{p-1}{p}-C_{1}\lambda ^{1-\sigma }\right]
\left\Vert u\left( t\right) \right\Vert _{p}^{p}+\varepsilon \left[
1-C_{1}\lambda ^{1-\sigma }\right] \beta \int\limits_{\Omega }F\left(
x,u\right) dx  \label{22s} \\
+\varepsilon \left( \left( 5p-1\right) -C_{1}\lambda ^{1-\sigma }\right)
H\left( t\right) .  \notag
\end{gather}%
chosen $\gamma _{1}=1+2\beta C\left( \sigma ,\alpha \right) ,\gamma
_{2}=1+3p\varepsilon e^{T}\beta l_{1}\frac{\delta ^{\sigma }}{\sigma }$ and $%
\lambda $ satisfying the following inequality%
\begin{equation*}
\lambda \geq \lambda _{0}=\min \left( \sqrt[\sigma -1]{\frac{2C_{1}}{3p-1}},%
\sqrt[\sigma -1]{\frac{pC_{1}}{p-1}},\sqrt[\sigma -1]{C_{1}},\sqrt[\sigma -1]%
{\frac{C_{1}}{5p-1}}\right)
\end{equation*}%
so that the coefficients of $H\left( t\right) ,$ $\left\vert u^{\prime
}\left( t\right) \right\vert ^{2},$ $\left\vert \Delta u\left( t\right)
\right\vert ^{2},$ $\left\Vert u\left( t\right) \right\Vert _{p}^{p}$ , $%
\left\Vert k_{1}\left( x\right) \right\Vert _{\infty }$, $\left\Vert
k_{2}\left( x\right) \right\Vert _{\infty }$ and $\int\limits_{\Omega
}F\left( x,u\right) dx$ in (\ref{22s}) are strictly positive, hence we get
\begin{gather}
\frac{d}{dt}G\left( t\right)  \notag \\
\geq \left(
\begin{array}{c}
\left( 1-a\right) \\
-\frac{\lambda }{\alpha d_{0}}\varepsilon \left(
\begin{array}{c}
3pe^{T}\beta C^{\ast }C\left( \Omega \right) ^{\frac{\sigma -2}{2\sigma }}
\\
+2\alpha \frac{\sigma -1}{\sigma }\left( C^{\ast }d_{1}C\left( \Omega
\right) ^{\frac{\sigma -2}{\sigma }}+d_{2}\right)%
\end{array}%
\right)%
\end{array}%
\right) H^{-a}\left( t\right) H^{\prime }\left( t\right)  \notag \\
+\omega \varepsilon \left(
\begin{array}{c}
H\left( t\right) +\left\vert u^{\prime }\left( t\right) \right\vert
^{2}+\left\Vert u\left( t\right) \right\Vert _{p}^{p}+\int_{\Omega }F\left(
x,u\right) dx \\
+\left\Vert k_{1}\left( x\right) \right\Vert _{\infty }+\left\Vert
k_{2}\left( x\right) \right\Vert _{\infty }^{\sigma }%
\end{array}%
\right) ,  \label{23s}
\end{gather}%
where $\omega $ is the minimum of these coefficients. We pick $\varepsilon $
small enough, so that
\begin{equation*}
0<\varepsilon \leq \varepsilon _{0}=\min \left(
\begin{array}{c}
\frac{1-a}{\frac{\lambda }{\alpha d_{0}}\left(
\begin{array}{c}
3pe^{T}\beta C^{\ast }C\left( \Omega \right) ^{\frac{\sigma -2}{2\sigma }}
\\
+2\alpha \frac{\sigma -1}{\sigma }\left( C^{\ast }d_{1}C\left( \Omega
\right) ^{\frac{\sigma -2}{\sigma }}+d_{2}\right)%
\end{array}%
\right) }; \\
\frac{H^{1-a}\left( 0\right) }{-L^{\prime }\left( 0\right) +3pe^{T}\beta
\int_{\Omega }F\left( x,u_{0}\right) dx}%
\end{array}%
\right)
\end{equation*}%
therefore (\ref{23s}) take the form
\begin{equation}
\frac{d}{dt}G\left( t\right) \geq \omega \varepsilon \left(
\begin{array}{c}
H\left( t\right) +\left\vert u^{\prime }\left( t\right) \right\vert
^{2}+\left\Vert u\left( t\right) \right\Vert _{p}^{p} \\
+\int_{\Omega }F\left( x,u\right) dx+\left\Vert k_{1}\left( x\right)
\right\Vert _{\infty }+\left\Vert k_{2}\left( x\right) \right\Vert _{\infty
}^{\sigma }%
\end{array}%
\right) ,  \label{24s}
\end{equation}%
hence%
\begin{equation*}
G\left( t\right) \geq G\left( 0\right) >0\text{ for all }t\geq 0.
\end{equation*}%
The second term in (\ref{7s}), by applying Young's inequality we can
estimate as follows%
\begin{equation*}
\frac{1}{2}L^{\prime }\left( t\right) =\left( u\left( t\right) ,u^{\prime
}\left( t\right) \right) \leq c\left\vert u^{\prime }\left( t\right)
\right\vert \left\Vert u\left( t\right) \right\Vert _{p}\leq c\left(
\left\vert u^{\prime }\left( t\right) \right\vert ^{2\left( 1-a\right)
}+\left\Vert u\left( t\right) \right\Vert _{p}^{\frac{2\left( 1-a\right) }{%
1-2a}}\right) ,
\end{equation*}%
so%
\begin{equation*}
\left\vert \left( u\left( t\right) ,u^{\prime }\left( t\right) \right)
\right\vert ^{\frac{1}{1-a}}\leq C\left( \left\vert u^{\prime }\left(
t\right) \right\vert ^{2}+\left\Vert u\left( t\right) \right\Vert _{p}^{%
\frac{2}{1-2a}}\right)
\end{equation*}%
using Lemma (\ref{Lemma1}) and the condition (\ref{8s}) we obtain
\begin{gather}
\left\vert \left( u\left( t\right) ,u^{\prime }\left( t\right) \right)
\right\vert ^{\frac{1}{1-a}}  \notag \\
\leq C\left( H\left( t\right) +\left\vert u^{\prime }\left( t\right)
\right\vert ^{2}+\left\Vert u\left( t\right) \right\Vert
_{p}^{p}+\int_{\Omega }F\left( x,u\right) dx\right) ,\text{ }\forall t\geq 0.
\label{25s}
\end{gather}%
Consequently we have%
\begin{gather}
G\left( t\right) ^{\frac{1}{1-a}}=\left( H^{1-a}\left( t\right)
+2\varepsilon \int_{\Omega }u\left( x,t\right) u^{\prime }\left( t\right)
dx+\gamma _{1}\varepsilon t\left\Vert k_{1}\left( x\right) \right\Vert
_{\infty }+\gamma _{2}\varepsilon t\left\Vert k_{2}\left( x\right)
\right\Vert _{\infty }^{\sigma }\right) ^{\frac{1}{1-a}}  \notag \\
\leq c\left( H\left( t\right) +\left\vert 2\varepsilon \int_{\Omega }u\left(
x,t\right) u^{\prime }\left( t\right) dx\right\vert ^{\frac{1}{1-a}%
}+\left\vert \gamma _{1}\varepsilon t\left\Vert k_{1}\left( x\right)
\right\Vert _{\infty }\right\vert ^{^{\frac{1}{1-a}}}+\left\vert \gamma
_{2}\varepsilon t\left\Vert k_{2}\left( x\right) \right\Vert _{\infty
}^{\sigma }\right\vert ^{^{\frac{1}{1-a}}}\right)  \notag \\
\leq C\left( H\left( t\right) +\left\vert u^{\prime }\left( t\right)
\right\vert ^{2}+\left\Vert u\left( t\right) \right\Vert
_{p}^{p}+\int_{\Omega }F\left( x,u\right) dx+\left\Vert k_{1}\left( x\right)
\right\Vert _{\infty }+\left\Vert k_{2}\left( x\right) \right\Vert _{\infty
}^{\sigma }\right) .  \label{26s}
\end{gather}%
We then combine (\ref{24s}), (\ref{25s}), and (\ref{26s}), to arrive at
\begin{equation}
\frac{d}{dt}G\left( t\right) \geq \rho G\left( t\right) ^{\frac{1}{1-a}},
\label{27s}
\end{equation}%
where $\rho $ is a constant depending on $C,$ $\omega $, and $\varepsilon $
only, and not depend of $u.$

Integrate (\ref{27s}) over $\left( 0,t\right) $ to get%
\begin{equation*}
G\left( t\right) ^{\frac{a}{1-a}}\geq \frac{1}{G^{\frac{a-1}{a}}\left(
0\right) -t\frac{a}{\left( 1-a\right) }\rho }.
\end{equation*}%
Therefore $G$ $\left( t\right) $ blows up in a finite time $T^{\ast }$ where
\begin{equation*}
T^{\ast }\leq \frac{1-a}{a\rho G^{\frac{a}{1-a}}\left( 0\right) }.
\end{equation*}
\end{proof}


\begin{thebibliography}{99}
\bibitem{Adams} Adams, R.A, \emph{Sobolev Spaces}. Academic Press, New York,
1975.

\bibitem{NOUR} Amroun, N.E., Benaissa, A., \emph{Global existence and energy
decay of solution to a petrovesky equation with general dissipation and
source term}, Georgian Math. J., \textbf{13}(2006), no. 3, 397--410.

\bibitem{ChenandZhou} Wenying, C., Yong, Z., \emph{Global nonexistence for a
semilinear petrovsky equation}, Nonlinear Anal., \textbf{70}(2009),
3203--3208.

\bibitem{DautryLions} Dautray, R., Lions, J.L., \emph{Analyse math\'{e}%
matique et calcul num\'{e}rique pour les sciences et les techniques},
volume~3. Masson, Paris, 1985.

\bibitem{PiskinPolat} Piskin, E., Polat, N., \emph{On the decay of solutions
for a nonlinear petrovskyequation}, Math. Sci. Lett., \textbf{3}(2014), no.
1, 43--47.

\bibitem{Li} Li, G., Sun, Y., Liu, W., \emph{Global existence and blow-up of
solutions for a strongly damped Petrovsky system with nonlinear damping},
Appl. Anal., \textbf{91}(2012), no. 3, 575--586.

\bibitem{GeorgievTodorova} Georgiev, V., Todorova, G., \emph{Existence of a
solution of the wave equation with nonlinear damping and source terms}, J.
Differential Equations., \textbf{109}(1994), no. 2, 295--308.

\bibitem{Guesmia} Guesmia, A., \emph{Existence globale et stabilisation
interne non lin\'{e}aire d'un syst\`{e}m de petrovsky}, Bull. Belg. Math.
Soc. Simon Stevin, \textbf{5}(1998), 583--594.

\bibitem{Lions2} Lions, J.L., \emph{Quelques m\'{e}thodes de r\'{e}solution
des probl\`{e}mes aux limites non lin\'{e}aires}, Dunod Gautier-Villars,
Paris, 1969.

\bibitem{Lions3} Lions, J.L., Magenes, E., \emph{Probl\`{e}mes aux limites
non homog\`{e}nes et applications}, volume 1, 2. Dunod, Paris, 1968.

\bibitem{Messaoudi} Messaoudi, S.A., \emph{Global existence and nonexistence
in a system of petrovsky}, J. Math. Anal. Appl., \textbf{265}(2002), no. 2,
296--308.

\bibitem{WuandTsai} Wu, S.T., Tsai, L.Y., \emph{On global solutions and
blow-up of solutions for a nonlinearly damped petrovsky system}, Taiwanese
J. Math., \textbf{19}(2009), no. 2A, 545--558.
\end{thebibliography}
\end{document}
