Hindawi Publishing Corporation Boundary Value Problems Volume 2011, Article ID 867615, 17 pages doi:10.1155/2011/867615 Research Article Multiple Positive Solutions for Second-Order p-Laplacian Dynamic Equations with Integral Boundary Conditions Yongkun Li and Tianwei Zhang Department of Mathematics, Yunnan University, Kunming, Yunnan 650091, China Correspondence should be addressed to Yongkun Li, yklie@ynu.edu.cn Received 13 July 2010; Revised 21 November 2010; Accepted 25 November 2010 Academic Editor: Gennaro Infante Copyright q 2011 Y. Li and T. Zhang. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. We are concerned with the following second-order p-Laplacian dynamic equations on time scales ϕp xΔ t∇ λft, xt, xΔ t 0, t ∈ 0, T T , with integral boundary conditions xΔ 0 0, T αxT − βx0 0 gsxs∇s. By using Legget-Williams fixed point theorem, some criteria for the existence of at least three positive solutions are established. An example is presented to illustrate the main result. 1. Introduction Boundary value problems with p-Laplacian have received a lot of attention in recent years. They often occur in the study of the n-dimensional p-Laplacian equation, non-Newtonian fluid theory, and the turbulent flow of gas in porous medium 1–7. Many works have been carried out to discuss the existence of solutions or positive solutions and multiple solutions for the local or nonlocal boundary value problems. On the other hand, the study of dynamic equations on time scales goes back to its founder Stefan Hilger 8 and is a new area of still fairly theoretical exploration in mathematics. Motivating the subject is the notion that dynamic equations on time scales can build bridges between continuous and discrete equations. Further, the study of time scales has led to several important applications, for example, in the study of insect population models, neural networks, heat transfer, and epidemic models, we refer to 8–10. In addition, the study of BVPs on time scales has received a lot of attention in the literature, with the pioneering existence results to be found in 11–16. However, existence results are not available for dynamic equations on time scales with integral boundary conditions. Motivated by above, we aim at studying the second-order 2 Boundary Value Problems p-Laplacian dynamic equations on time scales in the form of ∇ ϕp xΔ t λf t, xt, xΔ t 0, t ∈ 0, T T 1.1 with integral boundary condition xΔ 0 0, αxT − βx0 T gsxs∇s, 1.2 0 where λ is positive parameter, ϕp s |s|p−2 s for p > 1 with ϕ−1 p ϕq and 1/p 1/q 1, Δ is the delta derivative, ∇ is the nabla derivative, T is a time scale which is a nonempty closed subset of R with the topology and ordering inherited from R, 0 and T are points in T, an interval 0, T T : 0, T ∩ T, f ∈ C0, T T × R2 , 0, ∞ with ft, 0, 0 / 0 for all t ∈ 0, T T , T g ∈ Cld 0, T T , 0, ∞, α, β > 0 with α − g0 > β, and where g0 0 gs∇s. The main purpose of this paper is to establish some sufficient conditions for the existence of at least three positive solutions for BVPs 1.1-1.2 by using Legget-Williams fixed point theorem. This paper is organized as follows. In Section 2, some useful lemmas are established. In Section 3, by using Legget-Williams fixed point theorem, we establish sufficient conditions for the existence of at least three positive solutions for BVPs 1.1-1.2. An illustrative example is given in Section 4. 2. Preliminaries In this section, we will first recall some basic definitions and lemmas which are used in what follows. Definition 2.1 see 8. A time scale T is an arbitrary nonempty closed subset of the real set R with the topology and ordering inherited from R. The forward and backward jump operators σ, ρ : T → T and the graininess μ, ν : T → R are defined, respectively, by σt : inf{s ∈ T : s > t}, ρt : sup{s ∈ T : s < t}, μt : σt − t, νt : t − ρt. 2.1 The point t ∈ T is called left-dense, left-scattered, right-dense, or right-scattered if ρt t, ρt < t, and σt t or σt > t, respectively. Points that are right-dense and left-dense at the same time are called dense. If T has a left-scattered maximum m1 , defined Tκ T − {m1 }; otherwise, set Tκ T. If T has a right-scattered minimum m2 , defined Tκ T − {m2 }; otherwise, set Tκ T. Definition 2.2 see 8. For f : T → R and t ∈ Tκ , then the delta derivative of f at the point t is defined to be the number f Δ t provided it exists with the property that for each > 0, there is a neighborhood U of t such that fσt − fs − f Δ tσt − s ≤ |σt − s| ∀s ∈ U. 2.2 Boundary Value Problems 3 For f : T → R and t ∈ Tκ , then the nabla derivative of f at the point t is defined to be the number f ∇ t provided it exists with the property that for each > 0, there is a neighborhood U of t such that f ρt − fs − f ∇ t ρt − s ≤ ρt − s ∀s ∈ U. 2.3 Definition 2.3 see 8. A function f is rd-continuous provided it is continuous at each rightdense point in T and has a left-sided limit at each left-dense point in T. The set of rdcontinuous functions f will be denoted by Crd T. A function g is left-dense continuous i.e., ld-continuous if g is continuous at each left-dense point in T and its right-sided limit exists finite at each right-dense point in T. The set of left-dense continuous functions g will be denoted by Cld T. Definition 2.4 see 8. If F Δ t ft, then we define the delta integral by b fsΔs Fb − Fa. 2.4 a If G∇ t gt, then we define the nabla integral by b gs∇s Gb − Ga. 2.5 a Lemma 2.5 see 8. If f ∈ Crd T and t ∈ Tκ , then σt fsΔs μtft. 2.6 gs∇s νtgt. 2.7 t If g ∈ Cld T and t ∈ Tκ , then t ρt Let the Banach space 1 B Cld 0, T T x : 0, T T −→ R | x is Δ-differentiable on 0, T T , and xΔ is ld-continuous on0, T T 2.8 be endowed with the norm x max{x0 , xΔ 0 }, where x0 sup |xt|, t∈0,T T Δ x sup xΔ t 0 t∈0,T T 2.9 4 Boundary Value Problems and choose a cone P ⊂ B defined by ⎧ ⎫ Δ Δ∇ ⎪ ⎨x ∈ B : xt ≥ 0, x t ≤ 0, x t ≤ 0 ∀t ∈ 0, T T ,⎪ ⎬ T . P ⎪ ⎪ ⎩ ⎭ αxT − βx0 gsxs∇s 2.10 0 Lemma 2.6. If x ∈ P, then xt ≥ β/α − g0 x0 for all t ∈ 0, T T . Proof. If x ∈ P, then xΔ ≤ 0. It follows that x0 x0 max xt. xT min xt, t∈0,T T With αxT − βx0 T αxT βx0 0 t∈0,T T 2.11 gsxs∇s and xΔ ≤ 0, one obtains T T gsxs∇s ≥ βx0 0 gs∇sxT βx0 g0 xT . 2.12 0 Therefore, xT ≥ β β x0 x0 . α − g0 α − g0 2.13 From 2.11–2.13, we can get that β β x0 x0 . α − g0 α − g0 xt ≥ min xt xT ≥ t∈0,T T 2.14 So Lemma 2.6 is proved. Lemma 2.7. x ∈ B is a solution of BVPs 1.1-1.2 if and only if x ∈ B is a solution of the following integral equation: xt T Θ β V s ϕq 0 T s ϕq t s Δ λf r, xr, x r ∇r Δs 0 Δ 2.15 λf r, xr, x r ∇r Δs, 0 where 1 T Θ 1 , α − β − g0 α − β − 0 gs∇s t V t gs∇s ∀t ∈ 0, TT . 0 2.16 Boundary Value Problems 5 Proof. First assume x ∈ B is a solution of BVPs 1.1-1.2; then we have t t ϕp xΔ t ϕp xΔ 0 − λf s, xs, xΔ s ∇s − λf s, xs, xΔ s ∇s. 0 2.17 0 That is, Δ x t −ϕq t Δ λf s, xs, x s ∇s −Ht. 2.18 0 Integrating 2.18 from t to T , it follows that xt xT T 2.19 HsΔs. t Together with 2.19 and αxT − βx0 αxT − β xT T 0 gsxs∇s, we obtain T HsΔs 0 T gs xT 0 T HrΔr ∇s. 2.20 s Thus, α−β− T gs∇s xT β 0 T HsΔs 0 β β T HsΔs T T HsΔs − HrΔr ∇s s T T 0 0 β gs 0 0 T T T ∇ V s − V rHrΔr s ∇s 2.21 V 0 − V sHsΔs 0 HsΔs 0 T V sHsΔs, 0 namely, xT βΘ T 0 HsΔs Θ T 0 V sHsΔs. 2.22 6 Boundary Value Problems Substituting 2.22 into 2.19, we obtain T xt βΘ HsΔs Θ 0 T T V sHsΔs HsΔs 0 Θ β V s ϕq 0 T T λf r, xr, xΔ r ∇r Δs 2.23 0 s Δ λf r, xr, x r ∇r Δs. ϕq t s t 0 The proof of sufficiency is complete. Conversely, assume x ∈ B is a solution of the following integral equation: xt T Θ β V s ϕq 0 T s ϕq t T s λf r, xr, xΔ r ∇r Δs 0 λf r, xr, xΔ r ∇r Δs 0 Θ β V s HsΔs 2.24 T HsΔs. 0 t It follows that Δ x t −ϕq t Δ λf s, xs, x s ∇s −Ht, 0 ϕp 2.25 ∇ xΔ t λf t, xt, xΔ t 0. So xΔ 0 0. Furthermore, we have αxT − βx0 α T Θ β V s HsΔs − β 0 α−β T T Θ β V s HsΔs − β 0 Θ β V s HsΔs − β gsxs∇s 0 T T HsΔs, gs 0 0 Θ β V r HrΔr 0 HrΔr ∇s s T T gs∇s 0 T 0 Θ β V s HsΔs HsΔs 0 T 0 T T T T gsHrΔr∇s 0 s Boundary Value Problems 7 T T gs∇s 0 0 T T 0 Θ β V s HsΔs ∇ ∇s V s − V rHrΔr s T T gs∇s 0 Θ β V s HsΔs T 0 V sHsΔs, 0 2.26 which imply that αxT − βx0 − T gsxs∇s α − β 0 −β T T − T Θ β V s HsΔs 0 HsΔs − T 0 T gs∇s 0 Θ β V s HsΔs 0 V sHsΔs 0 0. 2.27 The proof of Lemma 2.7 is complete. Define the operator Ψ : P → B by Ψxt T Θ β V s ϕq 0 T s ϕq t s Δ λf r, xr, x r ∇r Δs 0 Δ 2.28 λf r, xr, x r ∇r Δs 0 for all t ∈ 0, T T . Obviously, Ψxt ≥ 0 for all t ∈ 0, T T . Lemma 2.8. If x ∈ P, then Ψx ∈ P. Proof. It is easily obtained from the second part of the proof in Lemma 2.7. The proof is complete. Lemma 2.9. Ψ : P → P is complete continuous. Proof. First, we show that Ψ maps bounded set into itself. Assume c is a positive constant and x ∈ Pc {x ∈ P : x ≤ c}. Note that the continuity of ft, x, xΔ guarantees that there is a 8 Boundary Value Problems C > 0 such that ft, x, xΔ ≤ ϕp C for all t ∈ 0, T T . So we get from ΨΔ x ≤ 0 and ΨΔ∇ x ≤ 0 that Ψx0 Ψx0 T s Θ β V s ϕq λf r, xr, xΔ r ∇r Δs 0 T s ϕq 0 Δ λf r, xr, x r ∇r Δs T 2.29 T Θ β V s Δs Cλq−1 T q , 0 Δ Ψ x ΨΔ xT ϕq 0 ≤ Cλq−1 T q−1 0 0 Δ λf r, xr, x r ∇r 2.30 0 ≤ Cλq−1 T q−1 . That is, ΨPc is uniformly bounded. In addition, notice that t1 s Δ λf r, xr, x r ∇r Δs |Ψxt1 − Ψxt2 | ϕq t2 0 ≤ Cλ q−1 q−1 T 2.31 |t1 − t2 |, which implies that |Ψxt1 − Ψxt2 | −→ 0 as t1 − t2 −→ 0, p−1 p−1 Δ ϕp ΨxΔ t1 − ϕp ΨxΔ t2 ΨxΔ t1 − Ψx t2 t1 Δ λf r, xr, x r ∇r t2 2.32 ≤ λϕp C|t1 − t2 |, which implies that p−1 p−1 Δ ΨxΔ t1 −→ 0 as t1 − t2 −→ 0. − t Ψx 2 2.33 ΨxΔ t1 − ΨxΔ t2 −→ 0 as t1 − t2 −→ 0. 2.34 That is, Boundary Value Problems 9 So Ψx is equicontinuous for any x ∈ Pc . Using Arzela-Ascoli theorem on time scales 17, we obtain that Ψ Pc is relatively compact. In view of Lebesgue’s dominated convergence theorem on time scales 18, it is easy to prove that Ψ is continuous. Hence, Ψ is complete continuous. The proof of this lemma is complete. Let υ and ω be nonnegative continuous convex functionals on a pone P, ψ a nonnegative continuous concave functional on P, and r, a, L positive numbers with r > a we defined the following convex sets: Pυ, r; ω, l {x ∈ P : υx < r, ωx < l}, Pυ, r; ω, l {x ∈ P : υx ≤ r, ωx ≤ l}, P υ, r; ω, l; ψ, a x ∈ P : υx < r, ωx < l, ψx > a , P υ, r; ω, l; ψ, a x ∈ P : υx ≤ r, ωx ≤ l, ψx ≥ a 2.35 and introduce two assumptions with regard to the functionals υ, ω as follows: H1 there exists M > 0 such that x ≤ M max{υx, ωx} for all x ∈ P; H2 Pυ, r; ω, l / ∅ for any r > 0 and l > 0. The following fixed point theorem duo to Bai and Ge is crucial in the arguments of our main result. Lemma 2.10 see 19. Let B be Banach space, P ⊂ B a cone, and r2 ≥ d > b > r1 > 0, l2 ≥ l1 > 0. Assume that υ and ω are nonnegative continuous convex functionals satisfying (H1) and (H2), ψ is a nonnegative continuous concave functional on P such that ψx ≤ υx for all x ∈ Pυ, r2 ; ω, l2 , and Ψ : Pυ, r2 ; ω, l2 → Pυ, r2 ; ω, l2 is a complete continuous operator. Suppose C1 {x ∈ Pυ, d; ω, l2 ; ψ, b} / ∅, ψΨx > b for x ∈ Pυ, d; ω, l2 ; ψ, b; C2 υΨx < r1 , ωΨx < l1 for x ∈ Pυ, r1 ; ω, l1 ; C3 ψΨx > b for x ∈ Pυ, r2 ; ω, l2 ; ψ, b with υΨx > d. Then Ψ has at least three fixed points x1 , x2 , x3 ∈ Pυ, r2 ; ω, l2 with x1 ∈ Pυ, r1 ; ω, l1 , x2 ∈ x ∈ P υ, r2 ; ω, l2 ; ψ, b : ψx > b , 2.36 x3 ∈ Pυ, r2 ; ω, l2 \ P υ, r2 ; ω, l2 ; ψ, b ∪ Pυ, r1 ; ω, l1 . 3. Main Result In this section, we will give sufficient conditions for the existence of at least three positive solutions to BVPs 1.1-1.2. 10 Boundary Value Problems Theorem 3.1. Suppose that there are positive numbers 0 < 0 < < T , l2 ≥ l1 > 0, and r2 > b > r1 > 0 with 0 , ∈ 0, T T , b/N ≤ min{r2 /K, l2 /L} and αb − g0 b ≤ r2 β such that the following conditions are satisfied. H3 ft, u, v ≤ min{ϕp r2 /K, ϕp l2 /L} for all t, u, v ∈ 0, T T × 0, r2 × −l2 , l2 , where Kλ q−1 T Θ β V s sq−1 Δs 0 T q−1 s Δs , L λq−1 T q−1 . 3.1 0 H4 ft, u, v < min{ϕp r1 /K, ϕp l1 /L} for all t, u, v ∈ 0, T T × 0, r1 × −l1 , l1 . H5 ft, u, v > ϕp b/N for all t, u, v ∈ 0 , T × b, αb − g0 b/β × −l2 , l2 , where Nλ q−1 − 0 q−1 T Θ β V s Δs. 3.2 Then BVPs 1.1-1.2 have at least three positive solutions. Proof. By the definition of the operator Ψ and its properties, it suffices to show that the conditions of Lemma 2.10 hold with respect to the operator Ψ. Let the nonnegative continuous convex functionals υ, ω and the nonnegative continuous concave functional ψ be defined on the cone P by ωx max xΔ t xΔ T , υx max |xt| x0, t∈0,T T t∈0,T T ψx min xt xT . t∈ ,T T 3.3 Then it is easy to see that x max{υx, ωx} and H1-H2 hold. First of all, we show that Ψ : Pυ, r2 ; ω, l2 → Pυ, r2 ; ω, l2 . In fact, if x ∈ Pυ, r2 ; ω, l2 , then υx max |xt| ≤ r2 , t∈0,T T ωx max xΔ t ≤ l2 t∈0,T T 3.4 and assumption H3 implies that r2 l2 f t, xt, x t ≤ min ϕp , ϕp ∀t ∈ 0, T T . K L Δ 3.5 Boundary Value Problems 11 On the other hand, for x ∈ P, there is Ψx ∈ P; thus υΨx max |Ψxt| t∈0,T T s T Δ λf r, xr, x r ∇r Δs max Θ β V s ϕq t∈0,T T 0 0 T s Δ ϕq λf r, xr, x r ∇r Δs t 0 s T Θ β V s ϕq λf r, xr, xΔ r ∇r Δs 0 0 T s Δ ϕq λf r, xr, x r ∇r Δs 0 0 T s r 2 ≤ ∇r Δs Θ β V s ϕq λϕp K 0 0 T s r 2 ∇r Δs ϕq λϕp K 0 0 s s r2 T r2 T Θ β V s ϕq λ∇r Δs ϕq λ∇r Δs K 0 K 0 0 0 T T q−1 r2 q−1 q−1 λ Θ β V s s Δs s Δs K 0 0 r2 ·K K r2 , ωΨx max ΨxΔ t t∈0,T T t Δ max −ϕq λf r, xr, x r ∇r t∈0,T T 0 ϕq T Δ λf r, xr, x r ∇r 0 ≤ ϕq T l2 ϕq L l2 ∇r λϕp L 0 T λ∇r 0 l2 . Therefore, Ψ : Pυ, r2 ; ω, l2 → Pυ, r2 ; ω, l2 . 3.6 12 Boundary Value Problems In the same way, if x ∈ Pυ, r1 ; ω, l1 , then assumption H4 implies r1 l1 f t, xt, xΔ t < min ϕp , ϕp ∀t ∈ 0, TT . K L 3.7 As in the argument above, we can get that Ψ : Pυ, r1 ; ω, l1 → Pυ, r1 ; ω, l1 . Thus, condition C2 of Lemma 2.10 holds. To check condition C1 in Lemma 2.10. Let d αb − g0 b/β. We choose xt ≡ d > b for t ∈ 0, T T . It is easy to see that xt ≡ d ∈ P υ, d; ω, l2 ; ψ, b , 3.8 ψx d > b. Consequently, x ∈ P υ, d; ω, l2 ; ψ, b : ψx > b / ∅. 3.9 Hence, for x ∈ Pυ, d; ω, l2 ; ψ, b, there are b ≤ xt ≤ d, Δ x t ≤ l2 ∀t ∈ , T T . 3.10 ∀t ∈ 0 , T . 3.11 In view of assumption H5, we have b f t, xt, xΔ t > ϕp N It follows that ψΨx min Ψxt t∈ ,T T ΨxT T s Δ Θ β V s ϕq λf r, xr, x r ∇r Δs 0 ≥ T 0 Θ β V s ϕq ≥ T ≥ Θ β V s ϕq > λf r, xr, xΔ r ∇r Δs 0 Θ β V s ϕq T λf r, xr, xΔ r ∇r Δs 0 T s Δ λf r, xr, x r ∇r Δs 0 Θ β V s ϕq λϕp 0 b ∇r Δs N Boundary Value Problems 13 λq−1 − 0 q−1 T N· b Θ β V s Δs N b N b. 3.12 Therefore, ψΨx > b for x ∈ Pυ, d; ω, l2 ; ψ, b. So condition C1 in Lemma 2.10 is satisfied. Finally, we show that C3 in Lemma 2.10 holds. In fact, for x ∈ Pυ, r2 ; ω, l2 ; ψ, b and υΨx > d αb − g0 b/β, we have ψΨx min Ψxt ΨxT ≥ t∈ ,T T β β max Ψxt υΨx > b. α − g0 t∈0,T T α − g0 3.13 Thus by Lemma 2.10 and the assumption that ft, 0, 0 / 0 on 0, T T , BVPs 1.1-1.2 have at least three positive solutions. The proof is complete. Theorem 3.2. Suppose that there are positive numbers 0 < ξ < T , l2 ≥ l1 > 0, and r2 > b > r1 > 0 with ξ ∈ 0, T T , b/F ≤ min{r 2 /K, l2 /L}, and αb−g0 b ≤ r2 β such that (H3)-(H4) and the following condition are satisfied. H6 ft, u, v > ϕp b/F for all t, u, v ∈ 0, ξT × b, αb − g0 b/β × −l2 , l2 , where F λq−1 ξq−1 T − ξ. 3.14 Then BVPs 1.1-1.2 have at least three positive solutions. Proof. Let the nonnegative continuous convex functionals υ, ω be defined on the cone P as Theorem 3.1 and the nonnegative continuous concave functional ψ be defined on the cone P by ψx min xt xξ. t∈0,ξT 3.15 We will show that condition C1 in Lemma 2.10 holds. Let d αb−g0 b/β. We choose xt ≡ d > b for t ∈ 0, T T . It is easy to see that xt ≡ d ∈ P υ, d; ω, l2 ; ψ, b , ψx d > b. 3.16 Consequently, x ∈ P υ, d; ω, l2 ; ψ, b : ψx > b / ∅. 3.17 14 Boundary Value Problems Hence, for x ∈ Pυ, d; ω, l2 ; ψ, b, there are Δ x t ≤ l2 ∀t ∈ 0, ξT . 3.18 b f t, xt, xΔ t > ϕp F ∀t ∈ 0, ξT . 3.19 b ≤ xt ≤ d, In view of assumption H6, we have It follows that ψΨx min Ψxt t∈0,ξT Ψxξ T s Θ β V s ϕq λf r, xr, xΔ r ∇r Δs 0 T s ϕq ξ ≥ T ≥ ϕq λf r, xr, xΔ r ∇r Δs 0 ξ T ϕq ξ 0 T ξ > λf r, xr, xΔ r ∇r Δs 0 s ξ 0 ϕq ξ 3.20 λf r, xr, xΔ r ∇r Δs b ∇r Δs λϕp F 0 λq−1 ξq−1 T − ξ F· b F b F b. Therefore, ψΨx > b for x ∈ Pυ, d; ω, l2 ; ψ, b. So condition C1 in Lemma 2.10 is satisfied. Using a similar proof to Theorem 3.1, the other conditions in Lemma 2.10 are satisfied. By Lemma 2.10, BVPs 1.1-1.2 have at least three positive solutions. The proof is complete. 4. An Example Example 4.1. Consider the following second-order Laplacian dynamic equations on time scales ∇ ϕ1.5 xΔ t f t, xt, xΔ t 0, t ∈ 0, 1T 4.1 Boundary Value Problems 15 with integral boundary condition xΔ 0 0, 3x1 − x0 1 4.2 es−1 xs∇s, 0 where ft, u, v ⎧ ⎨10−5 t 5|v| 6|u| ∀t, u, v ∈ 0, 1T × 0, 12 × −∞, ∞, ⎩10−5 t 5|v| 72 ∀t, u, v ∈ 0, 1T × 12, ∞ × −∞, ∞. 4.3 Then BVPs 4.1-4.2 have at least three positive solutions. Proof. Take 0 0.25, 0.5, r1 l1 0.009, r2 30000, l2 10000, and b 4. It follows that Θ 1 1 1 1, ≤ α − β − g0 3 − 1 − 1 es−1 ∇s 3 − 1 − 1 0 1 1 1 ≥ 0.5. Θ α − β − g0 3 − 1 − 1 es−1 ∇s 3 − 1 − e−1 0 4.4 From 4.1-4.2, it is easy to obtain V t V t K 1 t t gs∇s 0 gs∇s t 0 t 0 es−1 ∇s ≤ 1 ∀t ∈ 0, 1 T , es−1 ∇s ≥ e−1 ≥ 0.25 0 Θ1 V ss 3−1 0 N 0.5 − 0.253−1 Δs 1 ∀t ∈ 0, 1T , s3−1 Δs ≤ 3 K, L 1, 4.5 0 1 Θ1 V sΔs ≤ 0.07 N, 0.5 N 0.5 − 0.25 3−1 1 Θ1 V sΔs > 0.01. 0.5 Hence, we have r2 l2 b ≤ 400 < 10000 min , , N K L αb − g0 b − r2 β ≤ 12 − 30000 < 0. Moreover, we have 4.6 16 Boundary Value Problems H3 for all t, u, v ∈ 0, 1T × 0, 30000 × −10000, 10000, r2 r2 l2 l2 ≤ min ϕp , ϕp ; ft, u, v < 80 < 100 min ϕ1.5 , ϕ1.5 L K L K 4.7 H4 for all t, u, v ∈ 0, 1T × 0, 0.009 × −0.009, 0.009, ft, u, v ≤ 0.05401045 < min ϕ1.5 r1 l1 l1 , ϕ1.5 ≤ min ϕp , ϕp ; L K L K r1 4.8 H5 for all t, u, v ∈ 0.25, 0.5T × 4, 12 × −10000, 10000, ft, u, v ≥ 6|u| ≥ 24 > ϕ1.5 b . N 4.9 Therefore, conditions H3–H5 in Theorem 3.1 are satisfied. Further, it is easy to verify that the other conditions in Theorem 3.1 hold. By Theorem 3.1, BVPs 4.1-4.2 have at least three positive solutions. The proof is complete. Acknowledgment This work is supported the by the National Natural Sciences Foundation of China under Grant no. 10971183. References 1 D. O’Regan, “Some general existence principles and results for ϕy qft, y, y , 0 < t < 1,” SIAM Journal on Mathematical Analysis, vol. 24, no. 3, pp. 648–668, 1993. 2 M. del Pino, P. Drábek, and R. Manásevich, “The Fredholm alternative at the first eigenvalue for the one-dimensional p-Laplacian,” Journal of Differential Equations, vol. 151, no. 2, pp. 386–419, 1999. 3 A. Cabada and R. L. Pouso, “Existence results for the problem ϕy ft, y, y with nonlinear boundary conditions,” Nonlinear Analysis: Theory, Methods & Applications, vol. 35, no. 2, pp. 221–231, 1999. 4 H. Lü and C. Zhong, “A note on singular nonlinear boundary value problems for the one-dimensional p-Laplacian,” Applied Mathematics Letters, vol. 14, no. 2, pp. 189–194, 2001. 5 W. Feng and J. R. L. Webb, “Solvability of three point boundary value problems at resonance,” Nonlinear Analysis: Theory, Methods & Applications, vol. 30, no. 6, pp. 3227–3238, 1997. 6 C. P. Gupta, “A non-resonant multi-point boundary-value problem for a p-Laplacian type operator,” in Proceedings of the 5th Mississippi State Conference on Differential Equations and Computational Simulations (Mississippi State, MS, 2001), vol. 10 of Electron. J. Differ. Equ. Conf., pp. 143–152, Southwest Texas State University. 7 Y. Tian and W. Ge, “Periodic solutions of non-autonomous second-order systems with a p-Laplacian,” Nonlinear Analysis: Theory, Methods & Applications, vol. 66, no. 1, pp. 192–203, 2007. 8 M. Bohner and A. Peterson, Dynamic Equations on Time Scales: An Introduction with Applications, Birkhäuser, Boston, Mass, USA, 2001. 9 M. Bohner and A. Peterson, Eds., Advances in Dynamic Equations on Time Scales, Birkhäuser, Boston, Mass, USA, 2003. Boundary Value Problems 17 10 R. P. Agarwal, M. Bohner, and W.-T. Li, Nonoscillation and Oscillation: Theory for Functional Differential Equations, vol. 267 of Monographs and Textbooks in Pure and Applied Mathematics, Marcel Dekker, New York, NY, USA, 2004. 11 H.-R. Sun, L.-T. Tang, and Y.-H. Wang, “Eigenvalue problem for p-Laplacian three-point boundary value problems on time scales,” Journal of Mathematical Analysis and Applications, vol. 331, no. 1, pp. 248–262, 2007. 12 L. Jiang and Z. Zhou, “Existence of weak solutions of two-point boundary value problems for secondorder dynamic equations on time scales,” Nonlinear Analysis: Theory, Methods & Applications, vol. 69, no. 4, pp. 1376–1388, 2008. 13 Y. Tian and W. Ge, “Existence and uniqueness results for nonlinear first-order three-point boundary value problems on time scales,” Nonlinear Analysis: Theory, Methods & Applications, vol. 69, no. 9, pp. 2833–2842, 2008. 14 N. Aykut Hamal and Fulya Yoruk, “Positive solutions of nonlinear m-point boundary value problems on time scales,” Journal of Computational and Applied Mathematics, vol. 231, no. 1, pp. 92–105, 2009. 15 H.-R. Sun, “Triple positive solutions for p-Laplacian m-point boundary value problem on time scales,” Computers & Mathematics with Applications, vol. 58, no. 9, pp. 1736–1741, 2009. 16 Y. Yang and F. Meng, “Positive solutions of the singular semipositone boundary value problem on time scales,” Mathematical and Computer Modelling, vol. 52, no. 3-4, pp. 481–489, 2010. 17 R. P. Agarwal, M. Bohner, and P. Rehák, “Half-linear dynamic equations,” in Nonlinear Analysis and Applications: To V. Lakshmikantham on His 80th Birthday, vol. 1, pp. 1–57, Kluwer Academic Publishers, Dordrecht, The Netherlands, 2003. 18 B. Aulbach and L. Neidhart, “Integration on measure chains,” in Proceedings of the 6th International Conference on Difference Equations, pp. 239–252, CRC Press, Boca Raton, Fla, USA. 19 Z. Bai and W. Ge, “Existence of three positive solutions for some second-order boundary value problems,” Computers & Mathematics with Applications, vol. 48, no. 5-6, pp. 699–707, 2004.