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Existence of Solutions and Nonnegative Solutions for Prescribed Variable Exponent Mean Curvature Impulsive System Initialized Boundary Value Problems
Journal of Inequalities and Applicationsvolume 2010, Article number: 915739 (2010)
Abstract
This paper investigates the existence of solutions and nonnegative solutions for prescribed variable exponent mean curvature impulsive system initialized boundary value problems. The proof of our main result is based upon LeraySchauder's degree. The sufficient conditions for the existence of solutions and nonnegative solutions have been given.
1. Introduction
The theory of impulsive differential equations describes processes which experience a sudden change of their state at certain moments. On the Laplacian impulsive differential equations boundary value problems, there are many results (see [1–5]). Because of the nonlinearity of Laplacian, the results about Laplacian impulsive differential equations boundary value problems are rare (see [6]). In [7, 8], the authors discussed the existence of solutions of Laplacian system impulsive boundary value problems. Recently, the existence and asymptotic behavior of solutions of curvature equations have been studied extensively (see [9–15]). In [16], the authors generalized the usual mean curvature systems to variable exponent mean curvature systems. In this paper, we consider the existence of solutions and nonnegative solutions for the prescribed variable exponent mean curvature system
where , with the following impulsive initialized boundary value conditions
where
are absolutely continuous, where satisfy , is called the variable exponent mean curvature operator, and .
For any , will denote the th component of ; the inner product in will be denoted by will denote the absolute value and the Euclidean norm on . Denote that , , and , , , where ,. Denote that is the interior of ,. Let
For any , denote that . Obviously, is a Banach space with the norm , and is a Banach space with the norm . In the following, and will be simply denoted by and , respectively. Denote that , and the norm in is .
The study of differential equations and variational problems with variable exponent conditions is a new and interesting topic. For the applied background on this kind of problems we refer to [17–19]. Many results have been obtained on this kind of problems, for example, [20–35]. If (a constant) and (a constant), then (1.1) is the wellknown mean curvature system. Since problems with variable exponent growth conditions are more complex than those with constant exponent growth conditions, many methods and results for the latter are invalid for the former; for example, if is a bounded domain, the Rayleigh quotient
is zero in general, and only under some special conditions (see [25]), but the fact that is very important in the study of Laplacian problems.
In this paper, we investigate the existence of solutions for the prescribed variable exponent mean curvature impulsive differential system initialized boundary value problems; the proof of our main result is based upon LeraySchauder's degree. This paper was motivated by [6, 13, 36].
Let , then the function is assumed to be Caratheodory; by this we mean that
(i)for almost every the function is continuous,
(ii)for each the function is measurable on ,
(iii)for each there is a such that, for almost every and every with , , one has
We say a function is a solution of (1.1) if with absolutely continuous on , , which satisfies (1.1) on .
This paper is divided into three sections; in the second section, we present some preliminary. Finally, in the third section, we give the existence of solutions and nonnegative solutions for system (1.1)–(1.4).
2. Preliminary
In this section, we will do some preparation.
Lemma 2.1 (see [16]).
is a continuous function and satisfies the following.
(i)For any is strictly monotone, that is,
(ii)For any fixed , is a homeomorphism from to
For any , denote by the inverse operator of , then
Let one now consider the following simple problem:
with the following impulsive boundary value conditions:
where ;.
Obviously, implies that If is a solution of (2.4) with (2.5), by integrating (2.4) from to , then one finds that
Define , and operator as
From the definition of , one can see that
Denote that
By (2.6), one has
Denote that with the norm
then is a Banach space.
Let one define the nonlinear operator as
Lemma 2.2.
The operator is continuous and sends closed equiintegrable subsets of into relatively compact sets in .
Proof.
It is easy to check that , for all . Since
it is easy to check that is a continuous operator from to .
Let now be a closed equiintegrable set in , then there exists , such that, for any ,
We want to show that is a compact set.
Let is a sequence in , then there exists a sequence such that . For any , we have that
Hence the sequence is uniformly bounded and equicontinuous. By AscoliArzela theorem, there exists a subsequence of (which we rename the same) that is convergent in . Then the sequence
is convergent according to the norm in . Since
according to the continuity of , we can see that is convergent in . Thus we conclude that is convergent in . This completes the proof.
We denote that is the Nemytski operator associated to defined by
Define as
where .
Lemma 2.3.
is a solution of (1.1)–(1.4) if and only if is a solution of the following abstract equation:
where , .
Proof.

(i)
If is a solution of (1.1)–(1.4), since implies that , by integrating (1.1) from to , then we find that
(221)
Thus
Hence is a solution of (2.20).

(ii)
If is a solution of (2.20), then it is easy to see that (1.2) is satisfied. Let , then we have
(223)
From (2.20) we also have
From (2.24), we can see that (1.3) is satisfied. Let , from (2.24), then we have
Since we must have ; thus,
Hence is a solution of (1.1)–(1.4). This completes the proof.
3. Main Results and Proofs
In this section, we will apply LeraySchauder's degree to deal with the existence of solutions for (1.1)–(1.4).
We assume that
(H) for all
Theorem 3.1.
If (H) is satisfied, then is an open bounded set in such that the following conditions hold.
(1) For any the mapping belongs to .
(2) For each , the problem
has no solution on .
Then (1.1)–(1.4) has at least one solution on .
Proof.
Denote that
For any , define as
Denote that
We know that (1.1)–(1.4) has the same solutions of
Since is Caratheodory, it is easy to see that is continuous and sends bounded sets into equiintegrable sets. According to Lemma 2.2, we can conclude that is compact continuous on for any . We assume that for (3.4) does not have a solution on ; otherwise, we complete the proof. Now from hypothesis (2), it follows that (3.4) has no solution for ,.
When , (3.1) is equivalent to the following usual problem:
where obviously is the unique solution to this problem.
Since , we have proved that (3.4) has no solution ,on , then we get that, for each , LeraySchauder's degree is well defined. From the homotopy invariant property of that degree, we have
This completes the proof.
In the following, we will give an application of Theorem 3.1.
Denote that and
Obviously, is an open subset of .
Assume that
(H), where is a positive parameter, and is Caratheodory.
(H), for all.
Theorem 3.2.
If are satisfied, then problem (1.1)–(1.4) has at least one solution on , when positive parameter is small enough.
Proof.
Let one consider the problem
where is defined in (3.3).
Obviously, is a solution of (1.1)–(1.4) if and only if is a solution of the abstract equation (3.8) when . We only need to prove that the conditions of Theorem 3.1 are satisfied.
(1) When positive parameter is small enough, for any , we can see that the mapping belongs to .
(2) We shall prove that for each the problem
has no solution on .
If it is false, then there exists a and is a solution of (3.8). Then there exists an such that .

(i)
Suppose that , then . For any since according to (H) and (1.2), we have
(310)
It is a contradiction.

(ii)
Suppose that , . This implies that for some .
Denote that
Since we have
According to (H)(H), when positive parameter is small enough, we have
It is a contradiction.
Summarizing this argument, for each the problem (3.8) with (1.4) has no solution on .
Since and is the unique solution of , then the LeraySchauder's degree
This completes the proof.
In the following, we will discuss the existence of nonnegative solutions of (1.1)–(1.4). For any , the notation means that for every .
Assume the following
(H) where is a positive parameter, and
where , and for all .
(H)and for all ,.
(H).
(H) satisfies for all .
Theorem 3.3.
If HH are satisfied, then the problem (1.1)–(1.4) has a nonnegative solution, when positive parameter is small enough.
Proof.
From Theorem 3.2, we can get the existence of solutions of (1.1)–(1.4). If is a solution of (1.1)–(1.4), according to (1.4) and (H), then we have
Obviously
When , we have
then we can see that there exists a such that when . Thus for any . Thus is increasing in , that is, for any with . Since , it is easy to see that for any . From (3.17) and (H), we can easily see that
From (H), we can see that
Similarly, we can see that
Repeating the step, we can see that
Hence is nonnegative. This completes the proof.
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Acknowledgments
This paper is partly supported by the National Science Foundation of China (10701066, 10926075 and 10971087), China Postdoctoral Science Foundation funded project (20090460969), the Natural Science Foundation of Henan Education Committee (200875565), and the Natural Science Foundation of Jiangsu Education Committee (08KJD110007).
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Keywords
 Sudden Change
 Euclidean Norm
 Differential System
 Positive Parameter
 Invariant Property