Hindawi Publishing Corporation Abstract and Applied Analysis Volume 2012, Article ID 954352, 13 pages doi:10.1155/2012/954352 Research Article Smooth Solutions of a Class of Iterative Functional Differential Equations Houyu Zhao School of Mathematics, Chongqing Normal University, Chongqing 401331, China Correspondence should be addressed to Houyu Zhao, houyu19@gmail.com Received 14 December 2011; Accepted 5 March 2012 Academic Editor: Miroslava Růžičková Copyright q 2012 Houyu Zhao. 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. By Faà di Bruno’s formula, using the fixed-point theorems of Schauder and Banach, we study the existence and uniqueness of smooth solutions of an iterative functional differential equation x t 1/c0 x0 t c1 x1 t · · · cm xm t. 1. Introduction There has been a lot of monographs and research articles to discuss the kinds of solutions of functional differential equations since the publication of Jack Hale’s paper 1. Several papers discussed the iterative functional differential equations of the form x t H x0 t, x1 t, . . . , xm t , 1.1 where x0 t t, x1 t xt, xk t xxk−1 t, k 2, . . . , m. More specifically, Eder 2 considered the functional differential equation x t x2 t 1.2 and proved that every solution either vanishes identically or is strictly monotonic. Furthermore, Fečkan 3 and Wang 4 studied the equation x t f x2 t 1.3 2 Abstract and Applied Analysis with different conditions. Staněk 5 considered the equation x t xt x2 t 1.4 and obtained every solution either vanishes identically or is strictly monotonic. Si and his coauthors 6, 7 studied the following equations: x t xm t, 1 x t m , x t x t 1.5 1 c0 x0 t c1 x1 t · · · cm xm t 1.6 and established sufficient conditions for the existence of analytic solutions. Especially in 8, 9, the smooth solutions of the following equations: x t m aj xj t Ft, j1 x t m 1.7 j aj tx t Ft, j1 have been studied by the fixed-point theorems of Schauder and Banach. A smooth function is taken to mean one that has a number of continuous derivatives and for which the highest continuous derivative is also Lipschitz. Let x ∈ Cn if x , . . . , xn are continuous, Cn I, I is the set in which x ∈ Cn and maps a closed interval I into I. As in 9, we, using the same symbols, denote the norm xn n k x , k0 x max{|xt|}, t∈I 1.8 then Cn I, R with · n is a Banach space, and Cn I, I is a subset of Cn I, R. For given Mi > 0 i 1, 2, . . . , n 1, let ΩM1 , . . . , Mn1 ; I x ∈ Cn I, I : xi t ≤ Mi , i 1, 2, . . . , n; n x t1 − xn t2 ≤ Mn1 |t1 − t2 |, t, t1 , t2 ∈ I . 1.9 For convenience, we will make use of the notation xij t xi xj t , k x∗jk t xj t , 1.10 Abstract and Applied Analysis 3 where i, j, and k are nonnegative integers. Let I be a closed interval in R. By induction, we may prove that x∗jk t Pjk x10 t, . . . , x1,j−1 t; . . . ; xk0 t, . . . , xk,j−1 t , ⎛ ⎞ j terms j terms ⎜ ⎟ k k ⎟ βjk Pjk ⎜ ⎝x ξ, . . . , x ξ; . . . ; x ξ, . . . , x ξ⎠, Hjk ⎛ j terms ⎞ j terms j terms ⎜ ⎟ Pjk ⎝1, . . . , 1; M2 , . . . , M2 ; . . . ; Mk , . . . , Mk ⎠, 1.11 1.12 1.13 where Pjk is a uniquely defined multivariate polynomial with nonnegative coefficients. The proof can be found in 8. In order to seek a solution xt of 1.6, in Cn I, I such that ξ is a fixed point of the function xt, that is, xξ ξ, it is natural to seek an interval I of the form ξ − δ, ξ δ with δ > 0. Let us define Xξ; ξ0 , . . . , ξn ; 1, M2 , . . . , Mn1 ; I x ∈ Ω1, M2 , . . . , Mn1 ; I : xξ ξ0 ξ, xi ξ ξi , i 1, 2, . . . , n . 1.14 2. Smooth Solutions of 1.6 In this section, we will prove the existence theorem of smooth solutions for 1.6. First of all, we have the inequalities in the following for all xt, yt ∈ X: j x t1 − xj t2 ≤ |t1 − t2 |, t1 , t2 ∈ I, j 0, 1, . . . , m, j x − xj ≤ j x − y, j 1, . . . , m, 2.2 x − y ≤ δn xn − yn , 2.3 2.1 and the proof can be found in 9. Theorem 2.1. Let I ξ − δ, ξ δ, where ξ and δ satisfy ξ≥ where |c0 | > m i0 |c0 | − 1 m i1 |ci | , 0<δ≤ξ− |c0 | − 1 m i1 |ci | , 2.4 |ci |, then 1.6 has a solution in Xξ; ξ0 , . . . , ξn ; 1, M2 , . . . , Mn1 ; I, 2.5 4 Abstract and Applied Analysis provided the following conditions hold: i −1 m ci , ξ1 ξ −1 2.6 i0 −s−1 m s1 m −1s k − 1!s! i0 ci βi1 ξk ξ ci s1 !s2 ! · · · sk−1 ! 1! i0 s2 sk−1 m m i0 ci βi2 i0 ci βik−1 × ··· , 2! k − 1! 2.7 where k 2, . . . , n, and the sum is over all nonnegative integer solutions of the Diophantine equation s1 2s2 · · · k − 1sk−1 k − 1 and s s1 s2 · · · sk−1 , ii −s−1 m s1 m k − 1!s! i0 |ci |Hi1 −s−1 ξ − δ |c0 | − |ci | s1 !s2 ! · · · sk−1 ! 1! i1 s2 sk−1 m m i0 |ci |Hi2 i0 |ci |Hik−1 × ··· ≤ Mk , k 2, . . . , n, 2! k − 1! 2.8 where s1 2s2 · · · k − 1sk−1 k − 1 and s s1 s2 · · · sk−1 , iii n − 1!s! s1 !s2 ! · · · sn−1 !1!s1 2!s2 · · · n − 1!sn−1 ⎡ −s−2 s1 1 s2 m m m −s−2 × ⎣s 1ξ − δ |ci |Hi1 |ci |Hi2 |c0 | − |ci | × ··· × × m m i0 i1 sn−1 s1 ξ − δ−s−1 |ci |Hin−1 i0 i0 i1 s2 1 s3 sn−1 m m ··· |ci |Hi2 |ci |Hi3 |ci |Hin−1 i0 · · · sn−1 ξ − δ i0 i0 −s−1 |c0 | − m −s−1 m i1 i0 |ci | sn−1 −1 ⎤ m m × |ci |Hin−1 |ci |Hin ⎦ i0 i0 −s−1 s1 −1 m m |ci |Hi1 |c0 | − |ci | 2.9 s1 |ci |Hi1 ··· i0 ≤ Mn1 , where s1 2s2 · · · n − 1sn−1 n − 1 and s s1 s2 · · · sn−1 , m i0 sn−2 |ci |Hin−2 Abstract and Applied Analysis 5 Proof. Define an operator T from X into Cn I, I by T xt ξ t ξ 1 ds. c0 x0 s c1 x1 s · · · cm xm s 2.10 We will prove that for any x ∈ X, T x ∈ X, −1 m t 1 ds ≤ ξ − δ |c0 | − |ci | |t − ξ| ≤ δ, |T xt − ξ| m ξ i0 ci xi s i1 2.11 where the second inequality is from 2.4 and xI ⊆ I. Thus, T xI ⊆ I. It is easy to see that 1 , i c i0 i x t T x t m 2.12 and by Faà di Bruno’s formula, for k 2, . . . , n, we have k−1 m s1 i −1s k − 1!s! 1 1 i0 ci x t t m i s1 !s2 ! · · · sk−1 ! m ci xi t s1 1! i0 ci x t i0 ⎞ ⎛ m s2 k−1 sk−1 m i i i0 ci x t i0 ci x t ⎠ ⎝ × ··· 2! k − 1! m s1 −1s k − 1!s! 1 i0 ci x∗i1 t s1 !s2 ! · · · sk−1 ! m ci xi t s1 1! i0 m m s2 sk−1 i0 ci x∗i2 t i0 ci x∗ik−1 t × ··· , 2! k − 1! 2.13 k T x where the sum is over all nonnegative integer solutions of the Diophantine equation s1 2s2 · · · k − 1sk−1 k − 1 and s s1 s2 · · · sk−1 . 6 Abstract and Applied Analysis Furthermore, note T xξ ξ, by 2.6 and 2.7, 1 1 ξ1 , m i ξ ξ c x i0 ci i0 i s1 m −1s k − 1!s! 1 i0 ci x∗i1 ξ k T x ξ s1 !s2 ! · · · sk−1 ! ξ m ci s1 1! i0 s2 m m sk−1 i0 ci x∗i2 ξ i0 ci x∗ik−1 ξ × ··· 2! k − 1! s1 m −1s k − 1!s! 1 i0 ci βi1 s1 !s2 ! · · · sk−1 ! ξ m ci s1 1! i0 s2 sk−1 m m i0 ci βi2 i0 ci βik−1 × ··· 2! k − 1! ξk , k 2, . . . , n, T x ξ m 2.14 where s1 2s2 · · · k − 1sk−1 k − 1 and s s1 s2 · · · sk−1 . Thus, T xk ξ ξk for k 0, 1, . . . , n, −1 m 1 T x t ≤ 1 M1 , ≤ ξ − δ |c0 | − |ci | i m i0 ci x t i1 2.15 By 2.8, we have s1 m 1 k − 1!s! i0 |ci ||x∗i1 t| s1 !s2 ! · · · sk−1 ! m ci xi ts1 1! i0 s2 sk−1 m m i0 |ci ||x∗i2 t| i0 |ci ||x∗ik−1 t| × ··· 2! k − 1! −s−1 m s1 m k − 1!s! i0 |ci |Hi1 −s−1 ≤ ξ − δ |c0 | − |ci | s1 !s2 ! · · · sk−1 ! 1! i1 m m s2 sk−1 i0 |ci |Hi2 i0 |ci |Hik−1 × ··· 2! k − 1! ≤ Mk , k 2, . . . , n, T xk t ≤ where s1 2s2 · · · k − 1sk−1 k − 1 and s s1 s2 · · · sk−1 . 2.16 Abstract and Applied Analysis 7 Finally, T xn t1 − T xn t2 n − 1!s! ≤ s1 !s2 ! · · · sn−1 !1!s1 2!s2 · · · n − 1!sn−1 −s−1 s1 s2 sn−1 m m m m i × ci x t1 ci x∗i1 t1 ci x∗i2 t1 ··· ci x∗in−1 t1 i0 i0 i0 i0 −s−1 s1 s2 sn−1 m m m m − ci xi t2 ci x∗i1 t2 ci x∗i2 t2 ··· ci x∗in−1 t2 i0 i0 i0 i0 n − 1!s! ≤ s1 !s2 ! · · · sn−1 !1!s1 2!s2 · · · n − 1!sn−1 s 1 m 1 1 × |ci ||x∗i1 t1 | s1 − m s1 m i i i0 i0 ci x t1 i0 ci x t2 sn−1 −s−1 m m × ··· ci xi t2 |ci ||x∗in−1 t1 | i0 i0 s1 s1 s 2 m m m × ci x∗i1 t1 − ci x∗i1 t2 ··· |c ||x t | i0 i0 i ∗i2 1 i0 sn−1 −s−1 s 1 m m m i × ··· ci x t2 |ci ||x∗in−1 t1 | |ci ||x∗i1 t2 | i0 i0 i0 s 2 sn−2 m m × ··· |ci ||x∗i2 t2 | |ci ||x∗in−2 t2 | i0 i0 sn−1 sn−1 m m × ci x∗in−1 t1 − ci x∗in−1 t2 i0 i0 n − 1!s! ≤ s1 !s2 ! · · · sn−1 !1!s1 2!s2 · · · n − 1!sn−1 ⎡ −s−2 s1 1 s2 m m m −s−2 ⎣ × s 1ξ − δ |ci |Hi1 |ci |Hi2 |c0 | − |ci | i0 i1 i0 −s−1 sn−1 s1 −1 m m m −s−1 × ··· × s1 ξ − δ |ci |Hin−1 |ci |Hi1 |c0 | − |ci | i0 i0 i1 s2 1 s3 sn−1 m m m × ··· |ci |Hi2 |ci |Hi3 |ci |Hin−1 i0 i0 i0 −s−1 · · · sn−1 ξ − δ |c0 | − m −s−1 m i1 i0 |ci | sn−1 −1 ⎤ m m × |ci |Hin−1 |ci |Hin ⎦|t1 − t2 |, i0 s1 |ci |Hi1 ··· m sn−2 |ci |Hin−2 i0 i0 2.17 8 Abstract and Applied Analysis where s1 2s2 · · · k − 1sk−1 k − 1 and s s1 s2 · · · sk−1 . By 2.9, we see that T xn t1 − T xn t2 ≤ Mn1 |t1 − t2 |. Now, we can say that T is an operator from X into itself. Next, we will show that T is continuous. Let x, y ∈ X, then n k k T x − T y T x − T y x x − T y − Ty T T n k2 t 1 1 ds max − m m i s i s t∈I ξ c x c y i0 i i0 i 1 1 max m − m i i t∈I i0 ci x t i0 ci y t n k − 1!s! max t∈I s1 !s2 ! · · · sk−1 !1!s1 2!s2 · · · k − 1!sk−1 k2 1 × m i0 ci x × m i t s1 m s1 s2 m ci x∗i1 t ci x∗i2 t ··· i0 i0 sk−1 1 − m ci x∗ik−1 t i0 ci y i0 i t s1 m ci y∗i1 t s1 s2 sk−1 m m × ci y∗i2 t ··· ci y∗ik−1 t i0 i0 i0 −2 m m i i |ci |x − y |c0 | − |ci | ≤ δξ − δ−2 i1 i0 −2 m m i i |ci |x − y |c0 | − |ci | ξ − δ−2 i1 n i0 k − 1!s! t∈I s1 !s2 ! · · · sk−1 !1!s1 2!s2 · · · k − 1!sk−1 k2 ⎡ −s−1 −s−1 s1 m m m i i × ⎣ ci x t − ci y t ··· |ci ||x∗i1 t| i0 i0 i0 sk−1 −s−1 m m × ci yi t |ci ||x∗ik−1 t| i0 i0 max s1 s1 m m × ci x∗i1 t − ci y∗i1 t i0 i0 2.18 Abstract and Applied Analysis s2 sk−1 m m × ··· |ci ||x∗i2 t| |ci ||x∗ik−1 t| i0 9 i0 −s−1 s s m m m 1 k−2 i ··· ci y t ··· |ci | y∗i1 t |ci | y∗ik−2 t i0 i0 i0 sk−1 sk−1 m m × ci x∗ik−1 t − ci y∗ik−1 t i0 i0 ≤ ξ − δ −2 |c0 | − m −2 |c0 | |ci | i1 n k2 m i|ci | x − y i1 k − 1!s! s1 !s2 ! · · · sk−1 !1!s1 2!s2 · · · k − 1!sk−1 ⎡ × ⎣s 1ξ − δ −s−2 m |c0 | − −s−2 m i i |ci | |ci |x − y i0 i1 × m s1 ··· |ci |Hi1 m i0 sk−1 |ci |Hik−1 i0 s1 ξ − δ −s−1 |c0 | − m −s−1 s1 −1 m |ci | |ci |Hi1 i0 i1 × m s2 1 |ci |Hi2 ··· m i0 |ci |Hik−1 sk−1 m i0 i i |ci |x − y i0 −s−1 s1 m m ··· |ci |Hi1 |c0 | − |ci | · · · sk−1 ξ − δ−s−1 i0 i1 × m sk−2 sk−1 −1 m m ci Hik |ci |Hik−2 |ci |Hik−1 i0 × m i0 i0 i i |ci |x − y i0 δ n1 ξ − δ −2 m |c0 | − |ci | i1 −2 m |c0 | i|ci | xn − yn , i1 2.19 where s1 2s2 · · · k − 1sk−1 k − 1 and s s1 s2 · · · sk−1 . 10 Abstract and Applied Analysis Moreover, we can find some constants Pk such that n k − 1!s! s1 s2 sk−1 s !s ! · · · s 1 2 k−1 !1! 2! · · · k − 1! k2 ⎡ −s−2 m m i −s−2 i ⎣ × s 1ξ − δ |ci |x − y × |c0 | − |ci | × m ··· |ci |Hi1 i0 s1 ξ − δ × m m |c0 | − ··· |ci |Hi2 m × i0 sk−1 m i i |ci |Hik−1 |ci |x − y i0 2.20 i0 m |c0 | − |ci | −s−1 s1 m ··· |ci |Hi1 i0 i1 sk−2 sk−1 −1 m m ci Hik |ci |Hik−2 |ci |Hik−1 i0 m −s−1 s1 −1 m |ci | |ci |Hi1 m · · · sk−1 ξ − δ−s−1 × |ci |Hik−1 i1 s2 1 i0 m sk−1 i0 −s−1 i0 i1 s1 i0 i0 i i |ci |x − y i0 ≤ n−1 Pk ξ, δ, ci , Hij xk − yk , k1 where Pk ξ, δ, ci , Hij P ξ, δ; c1 , . . . , cm ; H11 , . . . , H1k1 ; . . . ; Hm1 , . . . , Hmk1 ; 2.21 are the positive constants depend on ξ, δ, ci , and Hij , i 1, . . . , m; j 1, . . . , k 1. Then −2 m m T x − T y ≤ ξ − δ−2 |c0 | − |ci | |c0 | i|ci | x − y n i1 n−1 Pk ξ, δ, ci , Hij xk − yk k1 δn1 ξ − δ−2 |c0 | − ≤ Γx − yn . m i1 i1 −2 |ci | |c0 | m i1 i|ci | xn − yn 2.22 Abstract and Applied Analysis 11 Here, ⎧ ⎨ Γ max ξ − δ ⎩ −2 m |c0 | − |ci | δ ξ − δ −2 m $ % |c0 | i|ci | ; max Pk ξ, δ, ci , Hij ; i1 n1 −2 |c0 | − m −2 |ci | i1 1≤k≤n−1 i1 |c0 | m i|ci | i1 ⎫ ⎬ 2.23 , ⎭ k 1, . . . , n − 1. So we can say that T is continuous. It is easy to see that X is closed and convex. We now show that X is a relatively compact subset of Cn I, I. For any x xt ∈ X, xn ≤ x n n k x ≤ |ξ| δ 1 Mk . k1 2.24 k2 Next, for any t1 , t2 in I, we have |xt1 − xt2 | ≤ |t1 − t2 |. 2.25 Hence, X is bounded in Cn I, I and equicontinuous on I, and by the Arzela-Ascoli theorem, we know X is relatively compact in Cn I, I, since Cn I, I is the subset of Cn I, R, and we can say that X is relatively compact in Cn I, R. From Schauder’s fixed-point theorem, we conclude that xt ξ t ξ 1 ds, c0 x0 s c1 x1 s · · · cm xm s 2.26 for some x xt in X. By differentiating both sides of the above equality, we see that x is the desired solution of 1.6. This completes the proof. Theorem 2.2. Let I ξ − δ, ξ δ, where ξ and δ satisfy 2.4, then 1.6 has a unique solution in Xξ; ξ0 , . . . , ξn ; 1, M2 , . . . , Mn1 ; I, 2.27 provided the conditions 2.6–2.9 hold and Γ < 1 in 2.23. Proof. Since Γ < 1, we see that T defined by 2.10 is contraction mapping on the close subset X of Cn I, I. Thus, the fixed point x in the proof of Theorem 2.1 must be unique. This completes the proof. Remark 2.3. By Theorem 2.1 or Theorem 2.2, the existence and uniqueness of smooth solutions of an iterative functional differential equation of the form 1.6 can be obtained. If n → ∞, we can also find that the solution is C∞ -smooth. 12 Abstract and Applied Analysis Now, we will show that the conditions in Theorem 2.1 do not self-contradict. Consider the following equation: x t 1 , t 1/2xt 1/4xxt 2.28 where c0 1, c1 1/2, c2 1/4, and ξ ≥ 4. Moreover, we take 0 < δ ≤ ξ − 4. Then, 2.4 is satisfied, and ξ, δ define the interval I ξ − δ, ξ δ. Now, take ξ0 ξ, 4 ξ1 ξ−1 , 7 16 −2 1 2 1 1 ξ1 ξ1 , ξ2 − ξ 49 2 4 2 4 −3 4 ξ 4 2ξ1 ξ12 − ξ−2 ξ2 2 ξ1 ξ12 , ξ3 343 49 2.29 then 2.6 and 2.7 are satisfied. Finally, if we take M1 1, M2 28ξ − δ−2 , M3 392ξ − δ−3 16ξ − δ−2 M2 2.30 as positive, and M4 8232ξ − δ−4 576ξ − δ−3 M2 8ξ − δ−2 6M22 5M3 , 2.31 then 2.8 and 2.9 are satisfied. Thus, we have shown that when ξ0 , . . . , ξ3 and M1 , . . . , M4 are defined as above, then there will be a solution for 2.28 in Xξ; ξ0 , . . . , ξ3 ; 1, . . . , M4 ; I. Acknowledgment This work was partially supported by the Natural Science Foundation of Chongqing Normal University Grant no. 12XLB003. References 1 J. Hale, Theory of Functional Differential Equations, Springer, New York, NY, USA, 2nd edition, 1977. 2 E. Eder, “The functional-differential equation x t xxt,” Journal of Differential Equations, vol. 54, no. 3, pp. 390–400, 1984. 3 M. Fečkan, “On a certain type of functional-differential equations,” Mathematica Slovaca, vol. 43, no. 1, pp. 39–43, 1993. 4 K. Wang, “On the equation x t fxxt,” Funkcialaj Ekvacioj, vol. 33, no. 3, pp. 405–425, 1990. 5 S. Staněk, “On global properties of solutions of functional-differential equation x t xxt xt,” Dynamic Systems and Applications, vol. 4, no. 2, pp. 263–277, 1995. 6 J.-G. Si, W.-R. Li, and S. S. Cheng, “Analytic solutions of an iterative functional-differential equation,” Computers & Mathematics with Applications, vol. 33, no. 6, pp. 47–51, 1997. Abstract and Applied Analysis 13 7 J. G. Si and W. N. Zhang, “Analytic solutions of a class of iterative functional differential equations,” Journal of Computational and Applied Mathematics, vol. 162, no. 2, pp. 467–481, 2004. 8 J.-G. Si and S. S. Cheng, “Smooth solutions of a nonhomogeneous iterative functional-differential equation,” Proceedings of the Royal Society of Edinburgh. Section A, vol. 128, no. 4, pp. 821–831, 1998. 9 J.-G. Si and X.-P. Wang, “Smooth solutions of a nonhomogeneous iterative functional-differential equation with variable coefficients,” Journal of Mathematical Analysis and Applications, vol. 226, no. 2, pp. 377–392, 1998. Advances in Operations Research Hindawi Publishing Corporation http://www.hindawi.com Volume 2014 Advances in Decision Sciences Hindawi Publishing Corporation http://www.hindawi.com Volume 2014 Mathematical Problems in Engineering Hindawi Publishing Corporation http://www.hindawi.com Volume 2014 Journal of Algebra Hindawi Publishing Corporation http://www.hindawi.com Probability and Statistics Volume 2014 The Scientific World Journal Hindawi Publishing Corporation http://www.hindawi.com Hindawi Publishing Corporation http://www.hindawi.com Volume 2014 International Journal of Differential Equations Hindawi Publishing Corporation http://www.hindawi.com Volume 2014 Volume 2014 Submit your manuscripts at http://www.hindawi.com International Journal of Advances in Combinatorics Hindawi Publishing Corporation http://www.hindawi.com Mathematical Physics Hindawi Publishing Corporation http://www.hindawi.com Volume 2014 Journal of Complex Analysis Hindawi Publishing Corporation http://www.hindawi.com Volume 2014 International Journal of Mathematics and Mathematical Sciences Journal of Hindawi Publishing Corporation http://www.hindawi.com Stochastic Analysis Abstract and Applied Analysis Hindawi Publishing Corporation http://www.hindawi.com Hindawi Publishing Corporation http://www.hindawi.com International Journal of Mathematics Volume 2014 Volume 2014 Discrete Dynamics in Nature and Society Volume 2014 Volume 2014 Journal of Journal of Discrete Mathematics Journal of Volume 2014 Hindawi Publishing Corporation http://www.hindawi.com Applied Mathematics Journal of Function Spaces Hindawi Publishing Corporation http://www.hindawi.com Volume 2014 Hindawi Publishing Corporation http://www.hindawi.com Volume 2014 Hindawi Publishing Corporation http://www.hindawi.com Volume 2014 Optimization Hindawi Publishing Corporation http://www.hindawi.com Volume 2014 Hindawi Publishing Corporation http://www.hindawi.com Volume 2014