Hindawi Publishing Corporation Abstract and Applied Analysis Volume 2012, Article ID 489353, 12 pages doi:10.1155/2012/489353 Research Article Monotonic Positive Solutions of Nonlocal Boundary Value Problems for a Second-Order Functional Differential Equation A. M. A. El-Sayed,1 E. M. Hamdallah,1 and Kh. W. El-kadeky2 1 2 Faculty of Science, Alexandria University, Alexandria, Egypt Faculty of Science, Garyounis University, Benghazi, Libya Correspondence should be addressed to Kh. W. El-kadeky, k welkadeky@yahoo.com Received 13 October 2011; Accepted 5 December 2011 Academic Editor: István Györi Copyright q 2012 A. M. A. El-Sayed et al. 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 study the existence of at least one monotonic positive solution for the nonlocal boundary value problem of the second-order functional differentialequation x t ft, xφt, t ∈ 0, 1, with n the nonlocal condition m j1 bj x ηj x1 , where τk ∈ a, d ⊂ 0, 1, k1 ak xτk x0 , x 0 ηj ∈ c, e ⊂ 0, 1, and x0 , x1 > 0. As an application the integral and the nonlocal conditions d xtdt x0 , x 0 xe − xc x1 will be considered. a 1. Introduction The nonlocal boundary value problems of ordinary differential equations arise in a variety of different areas of applied mathematics and physics. The study of nonlocal boundary value problems was initiated by Il’in and Moiseev 1, 2. Since then, the non-local boundary value problems have been studied by several authors. The reader is referred to 3–22 and references therein. In most of all these papers, the authors assume that the function f : 0, 1 × R → R is continuous. They all assume that lim x→∞ fx 0 or ∞, x fx 0 or ∞. lim x→0 x 1.1 2 Abstract and Applied Analysis These assumptions are restrictive, and there are many functions that do not satisfy these assumptions. Here we assume that the function f : 0, 1 × R → R is measurable in t ∈ 0, 1 for all x ∈ R and continuous in x ∈ R for almost all t ∈ 0, 1 is and there exists an integrable function a ∈ L1 0, 1 and a constant b > 0 such that ft, x ≤ |at| b|x|, ∀t, x ∈ 0, 1 × D. 1.2 Our aim here is to study the existence of at least one monotonic positive solution for the nonlocal problem of the second-order functional differential equation x t f t, x φt , t ∈ 0, 1, 1.3 with the nonlocal condition m ak xτk x0 , x 0 n bj x ηj x1 , 1.4 j1 k1 where τk ∈ a, d ⊂ 0, 1, ηj ∈ c, e ⊂ 0, 1, and x0 , x1 > 0. As an application, the problem with the integral and nonlocal conditions d xtdt x0 , x 0 xe − xc x1 , 1.5 a is studied. It must be noticed that the nonlocal conditions m xτ x0 , τ ∈ a, d , x 0 x η x1 , ak xτk 0, τk ∈ a, d, x 0 n bj x ηj 0, j1 k1 d xtdt 0, η ∈ c, e, ηj ∈ c, e, 1.6 x 0 xe xc a are special cases of our the nonlocal and integral conditions. 2. Integral Equation Representation Consider the functional differential equation 1.3 with the nonlocal condition 1.4 with the following assumptions. Abstract and Applied Analysis 3 i f : 0, 1 × R → R is measurable in t ∈ 0, 1 for all x ∈ R and continuous in x ∈ R for almost all t ∈ 0, 1 and there exists an integrable function a ∈ L1 0, 1, and a constant b > 0 such that ft, x ≤ |at| b|x|, ∀t, x ∈ 0, 1 × D. 2.1 ii φ : 0, 1 → 0, 1 is continuous. iii b < 1/3 − B, B nj1 bj 1−1 . iv m ak > 0, n ∀k 1, 2, . . . , m, bj > 0, ∀j 1, 2, . . . , n. 2.2 j1 k1 Now, we have the following Lemma. Lemma 2.1. The solution of the nonlocal problem 1.3-1.4 can be expressed by the integral equation xt A x0 − m k1 τk ak τk − sf s, x φs ds 0 ⎫ ⎧ ηj m n ⎨ ⎬ x − b f s, x φs ds B t − A ak τk ⎭ ⎩ 1 j1 j 0 k1 t 2.3 t − sf s, x φs ds, 0 where A m k1 ak −1 , B n j1 bj 1−1 . Proof. Integrating 1.3, we get x t x 0 t f s, x φs ds. 2.4 0 Integrating 2.4, we obtain xt x0 x 0t t t − sf s, x φs ds. 2.5 0 Let t τk , in 2.5, we get τk m n n m ak xτk ak x0 ak τk x 0 ak τk − sf s, x φs ds, k1 k1 k1 k1 0 2.6 4 Abstract and Applied Analysis and we deduce that x0 A x0 − m m ak τk x 0 − k1 τk ak τk − sf s, x φs ds , A 0 k1 m ak −1 . 2.7 k1 Substitute from 2.7 into 2.5, we obtain xt A x0 − m τk ak k1 t m τk − sf s, x φs ds x 0 t − A ak τk 0 k1 2.8 t − sf s, x φs ds. 0 Let t ηj , in 2.4, we obtain ηj n n n bj x ηj bj x 0 bj f s, x φs ds, j1 j1 x1 − x 0 x 0 0 j1 n ηj n bj bj f s, x φs ds, j1 2.9 0 j1 and we deduce that ⎞ ηj n x 0 B⎝x1 − bj f s, x φs ds⎠, ⎛ j1 ⎛ ⎞−1 n B ⎝ bj 1⎠ . 0 2.10 j1 Substitute from 2.10 into 2.8, we obtain τk m xt A x0 − ak τk − sf s, x φs ds 0 k1 B t−A m k1 t ak τk ⎧ ⎨ n ⎩ j1 x1 − ηj bj 0 ⎫ ⎬ f s, x φs ds , ⎭ 2.11 t − sf s, x φs ds, 0 which proves that the solution of the nonlocal problem 1.3-1.4 can be expressed by the integral equation 2.3. Abstract and Applied Analysis 5 3. Existence of Solution We study here the existence of at least one monotonic nondecreasing solution x ∈ C0, 1 for the integral equation 2.3. Theorem 3.1. Assume that (i)–(iv) are satisfied. Then the nonlocal problem 1.3-1.4 has at least one solution x ∈ C0, 1. Proof. Define the subset Qr ⊂ C0, 1 by Qr {x ∈ C : |xt| ≤ r, r Ax0 Bx1 3 − Ba/1 − 3 − Bb, r > 0}. Clear the set Qr which is nonempty, closed, and convex. Let H be an operator defined by τk m τk − sf s, x φs ds Hxt A x0 − ak 0 k1 ⎫ ⎧ ηj m n ⎨ ⎬ x − b f s, x φs ds B t − A ak τk ⎭ ⎩ 1 j1 j 0 k1 t t − sf s, x φs ds. 0 Let x ∈ Qr , then |Hxt| ≤ A x0 m τk ak τk − s f s, x φs ds 0 k1 ⎫ ⎧ ηj m n ⎨ ⎬ f s, x φs ds B t − A ak τk x1 bj ⎭ ⎩ 0 j1 k1 t t − sf s, x φs ds 0 ≤ A x0 B ⎧ ⎨ ⎩ 1 m 1 ak x1 |as| bx φs ds 0 k1 n 1 bj 0 j1 ⎫ ⎬ |as| bx φs ds ⎭ |as| bx φs ds 0 n ≤ Ax0 a b supx φt Bx1 B bj a t∈I bB j1 n bj supx φt a b supx φt j1 t∈I t∈I 3.1 6 Abstract and Applied Analysis ≤ Ax0 Bx1 2a 2bx 1 − Ba b1 − Bx ≤ Ax0 Bx1 3 − Ba 3 − Bbr ≤ r, 3.2 then H : Qr → Qr and {Hxt} is uniformly bounded in Qr . Also for t1 , t2 ∈ 0, 1 such that t1 < t2 , we have Hxt2 − Hxt1 B t2 − A m ⎫ ηj n ⎬ x − b f s, x φt ds ⎭ ⎩ 1 j1 j 0 ⎧ ⎨ ak τk k1 t2 t2 − sf s, x φt ds 0 − B t1 − A m ak τk k1 − t1 ⎫ ηj n ⎬ f s, x φt ds x − b ⎭ ⎩ 1 j1 j 0 ⎧ ⎨ t1 − sf s, x φt ds 0 ⎫ ⎧ ηj n ⎨ ⎬ Bt2 − t1 x1 − bj f s, x φt ds ⎭ ⎩ 0 j1 t1 t2 − t1 f s, x φt ds 0 t2 t2 − sf s, x φt ds. t1 Then ⎫ ηj n ⎬ |Hxt2 − Hxt1 | ≤ B|t2 − t1 | x1 bj |as| bx φs ds ⎭ ⎩ 0 j1 ⎧ ⎨ |t2 − t1 | t2 t1 t1 |as| bx φs ds 0 t2 − s |as| bx φs ds 3.3 Abstract and Applied Analysis 7 ≤ B|t2 − t1 |x1 n bj a br j1 |t2 − t1 |a br t2 ads brt2 − t1 . t1 3.4 The above inequality shows that |Hxt2 − Hxt1 | −→ 0 as t2 −→ t1 . 3.5 Therefore {Hxt} is equicontinuous. By the Arzelà-Ascoli theorem, {Hxt} is relatively compact. Since all conditions of the Schauder theorem hold, then H has a fixed point in Qr which proves the existence of at least one solution x ∈ C0, 1 of the integral equation 2.3, where τk m lim xt A x0 − ak τk − sf s, x φs ds t→0 0 k1 − BA m ak τk k1 ⎧ ⎨ n ⎩ j1 x1 − ηj bj 0 ⎫ ⎬ f s, x φs ds x0, ⎭ τk m lim− xt A x0 − ak τk − sf s, x φs ds t→1 k1 3.6 0 ⎫ ⎧ ηj m n ⎨ ⎬ f s, x φs ds B 1 − A ak τk x − b ⎭ ⎩ 1 j1 j 0 k1 1 1 − sf s, x φs ds x1. 0 To complete the proof, we prove that the integral equation 2.3 satisfies nonlocal problem 1.3-1.4. Differentiating 2.3, we get ⎫ ηj n ⎬ t f s, x φs ds f s, x φs ds, x t B x1 − bj ⎭ ⎩ 0 0 j1 ⎧ ⎨ x t f t, x φt . 3.7 3.8 8 Abstract and Applied Analysis Let t τk in 2.3, we obtain xτk A x0 − m τk ak τk − sf s, x φs ds 0 k1 τk τk − sf s, x φs ds, 3.9 0 which proves m ak xτk x0 . 3.10 k1 Also let t ηj in 3.7, we obtain ⎫ ⎧ ηj n ⎬ ηj ⎨ x ηj B x1 − bj f s, x φs ds f s, x φs ds, ⎭ ⎩ 0 0 j1 3.11 then ⎧ ⎫ ηj ηj n n n n ⎨ ⎬ bj x ηj B bj x1 − bj f s, x φs ds bj f s, x φs ds. ⎩ ⎭ 0 0 j1 j1 j1 j1 3.12 Let t 0 in 3.7, we obtain ⎫ ηj n ⎬ x 0 B x1 − bj f s, x φs ds . ⎭ ⎩ 0 j1 ⎧ ⎨ 3.13 Adding 3.12 and 3.13, we obtain x 0 n bj x ηj x1 . 3.14 j1 This implies that there exists at least one solution x ∈ C0, 1 of the nonlocal problem 1.3 and 1.4. This completes the proof. Abstract and Applied Analysis 9 Corollary 3.2. The solution of the problem 1.3-1.4 is monotonic nondecreasing. Proof. Let t1 < t2 , we deduce from 2.3 that τk m xt1 A x0 − ak τk − sf s, x φs ds 0 k1 B t1 − A m ⎫ ηj n ⎬ x − b f s, x φs ds ⎭ ⎩ 1 j1 j 0 ⎧ ⎨ ak τk k1 t1 t1 − sf s, x φs ds 0 τk m < A x0 − ak τk − sf s, x φs ds 0 k1 B t2 − A m ⎫ ηj n ⎬ x − b f s, x φs ds ⎭ ⎩ 1 j1 j 0 ⎧ ⎨ ak τk k1 t2 3.15 t2 − sf s, x φs ds xt2 , 0 which proves that the solution x of the problem 1.3-1.4 is monotonic nondecreasing. 3.1. Positive Solution Let bj 0, j 1, 2, . . . n and x1 0, then the nonlocal problem condition 1.4 will be m x 0 0. ak xτk x0 , 3.16 k1 Theorem 3.3. Let the assumptions (i)–(iv) of Theorem 3.1 be satisfied. Then the solution of the nonlocal problem 1.3–3.16 is positive t ∈ d, 1. Proof. Let bj 0, j 1, 2, . . . n and x1 0 in the integral equation 2.3 and the nonlocal condition 1.4, then the solution of the nonlocal problem 1.3–3.16 will be given by the integral equation xt A x0 − m τk ak k1 where A m k1 ak −1 . 0 τk − sf s, x φs ds t 0 t − s f s, x φs ds, 3.17 10 Abstract and Applied Analysis Let t ∈ d, 1, then τk τk − sf s, x φs ds ≤ t t − sf s, x φs ds, τk ≤ t, 0 0 τk t m m ak ak t − sf s, x φs ds. τk − sf s, x φs ds ≤ 0 k1 Multiplying by A 0 k1 m k1 3.18 ak −1 , we obtain τk t m m A ak τk − sf s, x φs ds ≤ A ak t − sf s, x φs ds k1 0 0 k1 t t − sf s, x φs ds, 3.19 0 and the solution x of the nonlocal problem 1.3 and 3.16, given by the integral equation 3.17, is positive for t ∈ d, 1. This complete the proof. Example 3.4. Consider the nonlocal problem of the second-order functional differential equation 1.3 with two-point boundary condition x 0 0, x η x0 , η ∈ a, d ⊂ 0, 1. 3.20 Applying our results here, we deduce that the two-point boundary value problem 1.3– 3.20 has at least one monotonic nondecreasing solution x ∈ C0, 1 represented by the integral equation xt x0 − η η − s f s, x φs ds t 0 t − sf s, x φs ds. 3.21 0 This the solution is positive with t > η. 4. Nonlocal Integral Condition Let x ∈ C0, 1 be the solution of the nonlocal problem 1.3 and 1.4. Let ak tk − tk−1 , τk ∈ tk−1 , tk ⊂ a, d ⊂ 0, 1 and let bj ξj − ξj−1 , ηj ∈ ξj−1 , ξj ⊂ c, e ⊂ 0, 1, then m k1 tk − tk−1 xτk x0 , x 0 n ξj − ξj−1 x ηj x1 . j1 4.1 Abstract and Applied Analysis 11 From the continuity of the solution x of the nonlocal problem 1.3 and 1.4, we obtain lim m m→∞ x 0 lim tk − tk−1 xτk d xsds, a k1 n n→∞ ξj − ξj−1 x ηj x 0 e 4.2 x sds, c j1 and the nonlocal condition 1.4 transformed to the integral condition d x 0 xe − xc x1 , xsds x0 , 4.3 a and the solution of the integral equation 2.3 will be xt d − a −1 x0 − d t a t − sf s, x φs ds dt 0 −1 b − c 1 t − 1 x1 − e t t f s, x φs ds dt c 4.4 0 f s, x φs ds. 0 Now, we have the following theorem. Theorem 4.1. Let the assumptions (i)–(iv) of Theorem 3.1 be satisfied. Then the nonlocal problem x t f t, x φt , d xsds x0 , t ∈ 0, 1 , x 0 xe − xc x1 4.5 a has at least one monotonic nondecreasing solution x ∈ C0, 1 represented by 4.4. References 1 V. A. Il’in and E. I. 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