Hindawi Publishing Corporation Advances in Difference Equations Volume 2011, Article ID 303472, 15 pages doi:10.1155/2011/303472 Research Article On Efficient Method for System of Fractional Differential Equations Najeeb Alam Khan,1 Muhammad Jamil,2, 3 Asmat Ara,1 and Nasir-Uddin Khan1 1 Department of Mathematics, University of Karachi, Karachi 75270, Pakistan Abdul Salam School of Mathematical Sciences, GC University, Lahore, Pakistan 3 Department of Mathematics, NEDUET, Karachi 75270, Pakistan 2 Correspondence should be addressed to Najeeb Alam Khan, njbalam@yahoo.com Received 14 December 2010; Accepted 5 February 2011 Academic Editor: J. J. Trujillo Copyright q 2011 Najeeb Alam Khan 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. The present study introduces a new version of homotopy perturbation method for the solution of system of fractional-order differential equations. In this approach, the solution is considered as a Taylor series expansion that converges rapidly to the nonlinear problem. The systems include fractional-order stiff system, the fractional-order Genesio system, and the fractional-order matrix Riccati-type differential equation. The new approximate analytical procedure depends only on two components. Comparing the methodology with some known techniques shows that the present method is relatively easy, less computational, and highly accurate. 1. Introduction Fractional differential equations have received considerable interest in recent years and have been extensively investigated and applied for many real problems which are modeled in different areas. One possible explanation of such unpopularity could be that there are multiple nonequivalent definitions of fractional derivatives 1. Another difficulty is that fractional derivatives have no evident geometrical interpretation because of their nonlocal character. However, during the last 12 years fractional calculus starts to attract much more attention of scientists. It was found that various, especially interdisciplinary, applications 2– 6 can be elegantly modeled with the help of the fractional derivatives. The homotopy perturbation method is a powerful devise for solving nonlinear problems. This method was introduced by He 7–9 in the year 1998. In this method, the solution is considered as the summation of an infinite series that converges rapidly. 2 Advances in Difference Equations This technique is used for solving nonlinear chemical engineering equations 10, timefractional Swift-Hohenberg S-H equation 11, viscous fluid flow equation 12, FourthOrder Integro-Differential equations 13, nonlinear dispersive Km, n, 1 equations 14, Long Porous Slider equation 15, and Navier-Stokes equations 16. It can be said that He’s homotopy perturbation method is a universal one, which is able to solve various kinds of nonlinear equations. The new homotopy perturbation method NHPM was applied to linear and nonlinear ODEs 17. In this paper, we construct the solution of system of fractional-order differential equations by extending the idea of 17, 18. This method leads to computable and efficient solutions to linear and nonlinear operator equations. The corresponding solutions of the integer-order equations are found to follow as special cases of those of fractional-order equations. We consider the system of fractional-order equations of the form Dαi yi t Fi t, y1 , y2 , y3 , . . . , yn fi t, yi t0 ci , 0 < αi ≤ 1, i 1, 2, . . . , n. 1.1 2. Basic Definitions We give some basic definitions, notations, and properties of the fractional calculus theory used in this work. Definition 2.1. The Riemann-Liouville fractional integral operator J μ of order μ on the usual Lebesgue space L1 a, b is given by 1 J fx Γ μ x μ x − tμ−1 ftdt, μ > 0, 0 2.1 J fx fx. 0 It has the following properties: i J μ exists for any x ∈ a, b, ii J μ J β J μβ , iii J μ J β J β J μ , iv J α J β fx J β J α fx, v J μ x − aγ Γγ 1/Γα γ 1x − aμγ , where f ∈ L1 a, b, μ, β ≥ 0 and γ > −1. Definition 2.2. The Caputo definition of fractal derivative operator is given by 1 Dμ fx J m−μ Dn fx Γ m−μ t 0 x − τm−μ−1 f m τdτ, 2.2 Advances in Difference Equations 3 where m − 1 < μ ≤ m, m ∈ N, x > 0. It has the following two basic properties for m − 1 < μ ≤ m and f ∈ L1 a, b: Dμ J μ fx fx, J μ Dμ fx fx − m−1 f k 0 k0 x − ak , k! x > 0. 2.3 3. Analysis of New Homotopy Perturbation Method Let us consider the system of nonlinear differential equations Ai yi fi t, t ∈ Ω, 3.1 where Ai are the operators, fi are known functions and yi are sought functions. Assume that operators Ai can be written as Ai yi Li yi Ni yi , 3.2 where Li are the linear operators and Ni are the nonlinear operators. Hence, 3.1 can be rewritten as follows: Li yi Ni yi fi t, t ∈ Ω. 3.3 We define the operators Hi as Hi Yi ; p ≡ 1 − p Li Yi − Li yi,0 p Ai Y − fi , where p ∈ 0, 1 is an embedding or homotopy parameter, Yi t; p : Ω × 0, 1 → are the initial approximation of solution of the problem in 3.3 can be written as Hi Yi ; p ≡ Li Yi − Li yi,0 pLi yi,0 p Ni Yi − fi . 3.4 Ê and yi,0 3.5 Clearly, the operator equations Hi v, 0 0 and Hi v, 1 0 are equivalent to the equations Li Yi − Lyi,0 0 and Ai Y − fi t 0, respectively. Thus, a monotonous change of parameter p from zero to one corresponds to a continuous change of the trivial problem Li Yi − Li yi,0 0 to the original problem. Operator Hi Yi , p is called a homotopy map. Next, we assume that the solution of equation Hi Yi , p can be written as a power series in embedding parameter p, as follows: Yi Yi,0 pYi,1 , i 1, 2, 3, . . . , n. 3.6 Now, let us write 3.5 in the following form: Li Yi yi,0 t p fi − Ni Yi − yi,0 t . 3.7 4 Advances in Difference Equations By applying the inverse operator, L−1 i to both sides of 3.7, we have −1 −1 −1 . y f − L N y Yi L−1 p L − L t Y t i,0 i i i,0 i i i i 3.8 Suppose that the initial approximation of 3.3 has the form yi,0 t ∞ i 1, 2, 3, . . . , n, ai,n Pn t, 3.9 n0 where ai,n , n 0, 1, 2, . . . are unknown coefficients and Pn t, n 0, 1, 2, . . . are specific functions on the problem. By substituting 3.6 and 3.9 into 3.8, we get Yi,0 pYi,1 L−1 i ∞ ai,n Pn t p L−1 i fi − L−1 i Ni Yi,0 pYi,1 − L−1 i ∞ n0 ai,n Pn t n0 . 3.10 Equating the coefficients of like powers of p, we get the following set of equations: −1 coefficient of p : Y0 L 0 ∞ ai,n Pn t , n0 −1 coefficient of p1 : Y1 L−1 fi L−1 i i Yi,1 − Li Ni Yi,0 . 3.11 Now, we solve these equations in such a way that Yi,1 t 0. Therefore, the approximate solution may be obtained as −1 yi t Yi,0 t L ∞ ai,n Pn t . 3.12 n0 4. Applications Application 1 Consider the following linear fractional-order 2-by-2 stiff system: Dtα ut k−1 − εut k1 − εvt, Dtα vt k1 − εut k−1 − εvt 4.1 with the initial conditions u0 1, v0 3, 4.2 Advances in Difference Equations 5 where k and ε are constants. To obtain the solution of 4.1 by NHPM, we construct the following homotopy: 1 − p Dtα Ut − u0 t p Dtα Ut − k−1 − εUt − k1 − εV t 0, 1 − p Dtα V t − v0 t p Dtα V t − k1 − εUt − k−1 − εV t 0. 4.3 Applying the inverse operator, Jtα of Dtα both sides of the above equation, we obtain Ut U0 Jtα u0 t − pJtα u0 t − k−1 − εUt − k1 − εV t, V t V 0 Jtα v0 t − pJtα v0 t − k1 − εUt − k−1 − εV t. 4.4 The solution of 4.1 to has the following form: Ut U0 t pU1 t, V t V0 t pV1 t. 4.5 Substituting 4.5 in 4.4 and equating the coefficients of like powers of p, we get the following set of equations: U0 t U0 Jtα u0 t, V0 t V 0 Jtα v0 t, U1 t Jtα −u0 t k−1 − εU0 t k1 − εV0 t, 4.6 V1 t Jtα −v0 t k1 − εU0 t k−1 − εV0 t. 20 k Assuming u0 t 20 n0 an Pn , v0 t n0 bn Pn , Pk t , U0 u0, and V 0 v0 and solving the above equation for U1 t and V1 t lead to the result U1 t a1 tα1 2a2 tα2 6a3 tα3 24a4 t2α 2k − 4εk − a0 tα − − − − ··· , Γα 1 Γα 2 Γα 3 Γα 4 Γα 5 4.7 b1 tα1 2b2 tα2 6b3 tα3 24b4 t2α −2k − 4εk − b0 tα − − − − ··· . V1 t Γα 1 Γα 2 Γα 3 Γα 4 Γα 5 Vanishing U1 t and V1 t lets the coefficients ai , bi , i 0, 1, 2, . . . by taking α 1 the following values: a0 2k1 − 2ε, −8k4 1 − 2ε4 , a3 3 8k7 1 − 2ε7 , a6 45 −8k10 1 − 2ε10 , a9 2835 a1 −4k2 1 − 2ε2 , 4k5 1 − 2ε5 a4 , 3 −16k8 1 − 2ε8 a7 , 315 8k11 1 − 2ε11 a10 , 14175 a2 4k3 1 − 2ε3 , −8k6 1 − 2ε6 a5 , 15 4k9 1 − 2ε9 a8 , 315 −16k12 1 − 2ε12 a11 , 155925 6 8k13 1 − 2ε13 , a12 467775 −16k16 1 − 2ε16 a15 , 155925 8k19 1 − 2ε19 , a18 97692469875 b0 −2k1 2ε, 8k4 1 2ε4 , b3 3 −8k7 1 2ε7 b6 , 45 8k10 1 2ε10 , b9 2835 −8k13 1 2ε13 b12 , 467775 16k16 1 2ε16 , b15 155925 −8k19 1 2ε19 , b18 97692469875 −16k14 1 − 2ε14 a13 , 6081075 4k17 1 − 2ε17 a16 , 638512875 −16k20 1 − 2ε20 a19 , 1856156927625 b1 4k2 1 2ε2 , Advances in Difference Equations 16k15 1 − 2ε15 a14 , 42567525 −8k18 1 − 2ε18 a17 , 10854718875 8k21 1 − 2ε21 a20 , 9280784638125 b2 −4k3 1 2ε3 , −4k5 1 2ε5 8k6 1 2ε6 b4 , b5 , 3 15 16k8 1 2ε8 −4k9 1 2ε9 b7 , b8 , 315 315 −8k11 1 2ε11 16k12 1 2ε12 b10 , b11 , 14175 155925 16k14 1 2ε14 −16k15 1 2ε15 b13 , b14 , 6081075 42567525 −4k17 1 2ε17 8k18 1 2ε18 b16 , b17 , 638512875 10854718875 16k20 1 2ε20 −8k21 1 2ε21 b19 , b20 . 1856156927625 9280784638125 4.8 Therefore, we obtain the solutions of 4.1 as 2k1 − 2εtα 4k2 1 − 2ε2 tα1 8k3 1 − 2ε3 tα2 16k4 1 − 2ε4 tα3 ut 1 − − ··· , Γα 1 Γα 2 Γα 3 Γα 4 2k1 2εtα 4k2 1 2ε2 tα1 8k3 1 2ε3 tα2 16k4 1 2ε4 tα3 vt 3 − − − ··· . Γα 1 Γα 2 Γα 3 Γα 4 4.9 Our aim is to study the mathematical behavior of the solution ut and vt for different values of α. This goal can be achieved by forming Pade’ approximants, which have the advantage of manipulating the polynomial approximation into a rational function to gain more information about ut and vt. It is well known that Pade’ approximants will converge on the entire real axis, if ut and vt are free of singularities on the real axis. It is of interest to note that Pade’ approximants give results with no greater error bounds than approximation by polynomials. To consider the behavior of solution for different values of α, we will take advantage of the explicit formula 4.9 available for 0 < α ≤ 1 and consider the following two special cases. Advances in Difference Equations 7 Case 1. Setting α 1, k 50, ε 0.01 in 4.9, we obtain the approximate solution in a series form as u10,11 t 1 148.73t 1203.65t2 51963.1t3 · · · , 1 50.7628t 1227.89t2 18726.5t3 · · · 4.10 3 69.439t 3823.59t2 40311.9t3 · · · v10,11 t . 1 57.1463t 1550.5t2 26447.2t3 · · · Case 2. In this case, we will examine the linear fractional stiff equation 4.1. Setting α 1/2, k 50, ε 0.01 in 4.9 gives ut 1 196t1/2 39992t3/2 7999984t5/2 228571424t7/2 − − ··· , √ √ √ √ π 3 π 15 π 15 π 4.11 204t1/2 13336t3/2 2666672t5/2 533333344t7/2 vt 3 − √ − − ··· . √ √ √ π π 5 π 35 π For simplicity, let t1/2 z, then 196z 39992z3 7999984z5 228571424z7 uz 1 √ − − ··· , √ √ √ π 3 π 15 π 15 π 4.12 204z 13336z3 2666672z5 533333344z7 − − ··· . vz 3 − √ √ √ √ π π 5 π 35 π Calculating the 10/11 Pade’ approximants and recalling that z t1/2 , we get u10,11 9.58 × 10−8 0.0000126t1/2 0.0002357t − 0.0001051t3/2 − · · · 9.581 × 10−8 2.0904 × 10−6 t1/2 4.56399 × 10−6 t 0.000096t2 · · · v10,11 2.66 × 10123 − 1.216 × 10125 t1/2 8.69947 × 10125 t · · · 8.88 × 10122 − 6.45605 × 10123 t1/2 4.22967 × 10124 t · · · , 4.13 . Application 2 Consider the following nonlinear fractional-order 2-by-2 stiff system: Dtα ut −1002ut 1000v2 t, Dtα vt ut − vt − v2 t 4.14 with the initial conditions u0 1, v0 1. 4.15 8 Advances in Difference Equations To obtain the solution of 4.14 by NHPM, we construct the following homotopy: 1 − p Dtα Ut − u0 t p Dtα Ut 1002Ut − 1000V 2t 0, 1 − p Dtα V t − v0 t p Dtα V t − Ut V t V 2 t 0. 4.16 Applying the inverse operator, Jtα of Dtα both sides of the above equation, we obtain Ut U0 Jtα u0 t − pJtα u0 t 1002Ut − 1000V 2 t , V t V 0 Jtα v0 t − pJtα v0 t − Ut V t V 2 t . 4.17 The solution of 4.14 to have the following form: Ut U0 t pU1 t, V t V0 t pV1 t. 4.18 Substituting 4.18 in 4.17 and equating the coefficients of like powers of p, we get the following set of equations: U0 t U0 Jtα u0 t, V0 t V 0 Jtα v0 t, U1 t Jtα −u0 t − 1002U0t 1000V02t , 4.19 V1 t Jtα −v0 t U0 t − V0 t − V02 t . 20 k Assuming u0 t 20 n0 an Pn , v0 t n0 bn Pn , Pk t , U0 u0, and V 0 v0 and solving the above equation for U1 t and V1 t lead to the result U1 t a1 tα1 2a2 tα2 6a3 tα3 24a4 tα4 −a0 2tα − − − − − ··· , Γα 1 Γα 2 Γα 3 Γα 4 Γα 5 b1 tα1 2b2 tα2 6b3 tα3 24b4 tα4 −b0 1tα − − − − −··· . V1 t Γα 1 Γα 2 Γα 3 Γα 4 Γα 5 4.20 Vanishing U1 t and V1 t lets the coefficients ai , bi , i 0, 1, 2, . . . to take the following values: a0 −2, a1 4, a2 −4, a3 8 −4 −8 , a4 , . . . , a20 , 3 3 9280784638125 −1 1 −1 −1 , b3 , b4 , . . . , b20 . b0 −1, b1 1, b2 2 6 24 2432902008176640000 4.21 Advances in Difference Equations 9 Therefore, we obtain the solution of 4.14 as ut 1 − 2tα 4tα1 8tα2 16tα3 32tα4 − − ··· , Γα 1 Γα 2 Γα 3 Γα 4 Γα 5 tα1 tα2 tα3 tα4 tα − − ··· . vt 1 − Γα 1 Γα 2 Γα 3 Γα 4 Γα 5 4.22 The exact solution of 4.14 for α 1 is ut e−2t , vt e−t . Application 3 Consider the following nonlinear Genesio system with fractional derivative: Dtα ut vt, Dtα vt wt, 4.23 Dtα wt −cut − bvt − awt u2 t with the initial conditions u0 0.2, v0 −0.3, w0 0.1, 4.24 where a, b, and c are constants. To obtain the solution of 4.23 by NHPM, we construct the following homotopy: 1 − p Dtα Ut − u0 t p Dtα Ut − V t 0, 1 − p Dtα V t − v0 t p Dtα V t − Wt 0, 1 − p Dtα Wt − w0 t p Dtα Wt cUt bV t aWt − U2 t 0. 4.25 Applying the inverse operator, Jtα of Dtα both sides of the above equation, we obtain Ut U0 Jtα u0 t − pJtα u0 t − V t, V t V 0 Jtα v0 t − pJtα v0 t − Wt, Wt Wt Jtα w0 t − pJtα w0 t cUt bV t aWt − U2 t . 4.26 The solution of 4.23 to have the following form: Ut U0 t pU1 t, V t V0 t pV1 t, Wt W0 t pW1 t. 4.27 10 Advances in Difference Equations Substituting 4.27 in 4.26 and equating the coefficients of like powers of p, we get the following set of equations: U0 t U0 Jtα u0 t, V0 t V 0 Jtα v0 t, W0 t W0 Jtα w0 t, U1 t Jtα −u0 t V0 t, 4.28 V1 t Jtα −v0 t W0 t, W1 t Jtα −w0 t − cU0 t − bV0 t − aV0 t W02 t . 20 20 k Assuming u0 t 20 n0 an Pn , v0 t n0 bn Pn , w0 t n0 cn Pn , Pk t , U0 u0, V 0 v0, W0 w0, a 1.2, b 2.92, and c 6, and solving the above equation for U1 t, V1 t and W1 t lead to the result U1 t −a0 3/10tα a1 tα1 2a2 tα2 6a3 tα3 24a4 tα4 − − − − − ··· , Γα 1 Γα 2 Γα 3 Γα 4 Γα 5 V1 t W1 t b1 tα1 2b2 tα2 6b3 tα3 24b4 tα4 b0 − 1/10tα − − − − − ··· , Γα 1 Γα 2 Γα 3 Γα 4 Γα 5 4.29 c1 tα1 2c2 tα2 6c3 tα3 24c4 tα4 −c0 101/250tα − − − − − ··· . Γα 1 Γα 2 Γα 3 Γα 4 Γα 5 Vanishing U1 t, V1 t, and W1 t lets the coefficients ai , bi , ci , i 0, 1, 2, . . . to take the following values: a0 b0 −3 , 10 1 , 10 a1 −101 , 250 a2 −101 , 500 a3 2341 , 7500 a4 −377 ,..., 6250 a20 −64170831419403533391899 , 1160098079765625000000000000000000 b1 −101 , 250 c1 b2 2341 , 2500 b3 −754 , 3125 b4 −5153 ,..., 75000 33855543777297749556491 , 89238313828125000000000000000000 b20 c0 1 , 10 23411 , 1250 c20 c2 −2262 , 3125 c3 −5153 , 75000 c4 5838803330656480870609733 . 19334967996093750000000000000000000 −508141 ,..., 3750000 4.30 Advances in Difference Equations 11 Therefore, we obtain the solutions of 4.23 as ut 3tα tα1 101tα2 2341tα3 4524tα4 1 − − − ··· , 5 10Γα 1 10Γα 2 250Γα 3 1250Γα 4 3125Γα 5 vt −3 tα 101tα1 2341tα2 4524tα3 5153tα4 − − − ··· , 10 10Γα 1 250Γα 2 1250Γα 3 3125Γα 4 3125Γα 5 wt 1 101tα 2341tα1 4524tα2 5153tα3 508141tα4 − − − − · · · . 10 250Γα 1 1250Γα 2 3125Γα 3 3125Γα 4 156250Γα 5 4.31 Application 4 Finally, we consider the following nonlinear matrix Riccati differential equation with fractional derivative: Dtα Y t −Y 2 t Q, Y 0 0, 4.32 1 0 1 1 where Q 1/2 11 −1 −1 1 . To find the solution of this equation by NHPM, we will 1 0 100 treat the matrix equation as a system of fractional-order differential equations Dtα ut −u2 t − vtzt 101 , 2 Dtα vt −utvt − vtwt − Dtα zt 99 , 2 99 −utvt − vtwt − , 2 Dtα wt −u2 t − vtzt 4.33 101 , 2 with the initial conditions u0 0, v0 0, z0 0, w0 0. 4.34 Therefore, we obtain the solution of 4.33 as ut wt vt zt 1 3tα tα1 101tα2 2341tα3 4524tα4 − − − · · · , 5 10Γα 1 10Γα 2 250Γα 3 1250Γα 4 3125Γα 5 −3 tα 101tα1 2341tα2 4524tα3 5153tα4 − − − · · · . 10 10Γα 1 250Γα 2 1250Γα 3 3125Γα 4 3125Γα 5 4.35 Advances in Difference Equations 3 3 2.5 2.5 u, v u, v 12 2 1.5 2 1.5 1 1 0 0.1 0.2 0.3 0.4 0.5 0 0.1 0.2 t 0.3 0.4 0.5 0.3 0.4 0.5 t a b 3 6 4 u, v u, v 2.5 2 2 0 1.5 −2 1 0 0.1 0.2 0.3 0.4 0.5 0 0.1 0.2 t c t d Figure 1: Solutions of linear stiff system for k 50, ε 0.01, α 1, a Exact, b Numerical, c NHPMPade 10/11, d NHPM-Pade 10/11, k 50, ε 0.01, α 0.5 color figure can be viewed in the online issue. 5. Concluding Remarks The NHPM for solving system of fractional-order differential equations are based on two component procedure and polynomial initial condition. The NHPM applied on fractionalorder Stiff equation, fractional Genesio equation, and the matrix Riccati-type differential equation. The Applications in problems 1–4 are plotted in Figures 1, 2, 3, and 4, which show the accuracy of NHPM. The computations associated with the applications discussed above, were performed by MATHEMATICA. The NHPM is very simple in application and is less computational more accurate in comparison with other mentioned methods. By using this method, the solution can be obtained in bigger interval. Unlike the ADM 19, the NHPM is free from the need to use Adomian polynomials. In this method, we do not need the Lagrange multiplier, correction functional, stationary conditions, and calculating integrals, which eliminate the complications that exist in the VIM 20. In contrast to the HPM and HAM, in this method, it is not required to solve the functional equations in each iteration. The efficiency of HAM is very much depended on choosing auxiliary parameter . All the applications are taken from 20 with fractional derivatives. 13 1 1 0.8 0.8 u, v u, v Advances in Difference Equations 0.6 0.6 0.4 0.4 0.2 0.2 0 0.2 0.4 0.6 0.8 1 0 0.2 0.4 0.6 t 0.8 1 t a b 1 1 0.9 0.8 0.7 u, v u, v 0.8 0.6 0.5 0.6 α 0.9 α 1/3 0.4 0.4 α 0.9 0.2 0.3 0 0.2 0.4 0.6 0.8 1 0 0.2 0.4 α 1/3 0.8 0.6 1 t t c d Figure 2: Solutions of nonlinear stiff system for α 1, a Exact, b Numerical, c NHPM, and c NHPM, α 0.9, 1/3 color figure can be viewed in the online issue. 0.4 w 0.3 0.3 0.2 0.2 0.1 u, v u, v 0.4 u 0 w 0.1 u 0 −0.1 −0.1 −0.2 v −0.2 v −0.3 −0.3 0 0.5 1 1.5 2 0 2.5 0.5 1 1.5 a 0.4 α 1 2 w 0.2 0.1 0.1 0 u −0.1 −0.2 α 0.75 w 0.3 0.2 0 2.5 b 0.4 u, v u, v 0.3 2 t t u −0.1 −0.2 v v −0.3 −0.3 0 0.5 1 1.5 2 0 0.5 1 c 1.5 2 t t d Figure 3: Solutions of nonlinear Genesio system for a Numerical, b NHPM α 1, c NHPM, α 0.5, d NHPM, α 0.75 color figure can be viewed in the online issue. 14 Advances in Difference Equations 4 4 2 2 u, v u, v 6 0 0 −2 −2 −4 −6 −4 0 0.5 1 1.5 2 2.5 3 0 0.5 1 1.5 t 2 2.5 3 t a b 10 u, v 5 0 −5 −10 0 0.5 1 1.5 2 2.5 3 t c Figure 4: Solutions of matrix Riccati equations u w, v z for α 1 a Numerical, b NHPM-Pade 9/11, c NHPM-Pade 9/11, α 0.5 color figure can be viewed in the online issue. Acknowledgment M. Jamil is highly thankful and grateful to the Abdus Salam School of Mathematical Sciences, GC University, Lahore, Pakistan, the Department of Mathematics & Basic Sciences, NED University of Engineering & Technology, Karachi-75270, Pakistan, and also the Higher Education Commission of Pakistan for generously supporting and facilitating this research work. References 1 H. M. Kilbas, H. M. Srivastava, and J. J. Trujillo, Theory and Applications of Fractional Differential Equations, Elsevier, Amsterdam, The Netherlands, 2007. 2 R. L. Bagley and R. A. Calico, “Fractional order state equations for the control of viscoelastically damped structures,” Journal of Guidance, Control, and Dynamics, vol. 14, no. 2, pp. 304–311, 1991. 3 A. Mahmood, S. Parveen, A. Ara, and N. A. Khan, “Exact analytic solutions for the unsteady flow of a non-Newtonian fluid between two cylinders with fractional derivative model,” Communications in Nonlinear Science and Numerical Simulation, vol. 14, no. 8, pp. 3309–3319, 2009. 4 A. Mahmood, C. Fetecau, N. A. Khan, and M. Jamil, “Some exact solutions of the oscillatory motion of a generalized second grade fluid in an annular region of two cylinders,” Acta Mechanica Sinica, vol. 26, no. 4, pp. 541–550, 2010. 5 J. H. He, “Nonlinear oscillation with fractional derivative and its applications,” in Proceedings of the International Conference on Vibrating Engineering, pp. 288–291, Dalian, China, 1998. Advances in Difference Equations 15 6 N. A. Khan, N.-U. Khan, A. Ara, and M. Jamil, “Approximate analytical solutionsof fractional reaction-diffusion equations,” Journal of King Saud University—Science. In press. 7 J.-H. He, “Homotopy perturbation technique,” Computer Methods in Applied Mechanics and Engineering, vol. 178, no. 3-4, pp. 257–262, 1999. 8 J.-H. He, “A coupling method of a homotopy technique and a perturbation technique for non-linear problems,” International Journal of Non-Linear Mechanics, vol. 35, no. 1, pp. 37–43, 2000. 9 J.-H. He, “Homotopy perturbation method: a new nonlinear analytical technique,” Applied Mathematics and Computation, vol. 135, no. 1, pp. 73–79, 2003. 10 N. A. Khan, A. Ara, and A. Mahmood, “Approximate solution of time-fractional chemical engineering equations: a comparative study,” International Journal of Chemical Reactor Engineering, vol. 8, article A19, 2010. 11 N. A. Khan, N.-U. Khan, M. Ayaz, and A. Mahmood, “Analytical methods for solving the timefractional Swift-Hohenberg S-H equation,” Computers and Mathematics with Applications. In press. 12 N. A. Khan, A. Ara, S. A. Ali, and M. Jamil, “Orthognal flow impinging on a wall with suction or blowing,” International Journal of Chemical Reactor Engineering. In press. 13 A. Yıldırım, “Solution of BVPs for fourth-order integro-differential equations by using homotopy perturbation method,” Computers & Mathematics with Applications, vol. 56, no. 12, pp. 3175–3180, 2008. 14 H. Koçak, T. Öziş, and A. Yıldırım, “Homotopy perturbation method for the nonlinear dispersive Km,n,1 equations with fractional time derivatives,” International Journal of Numerical Methods for Heat & Fluid Flow, vol. 20, no. 2, pp. 174–185, 2010. 15 Y. Khan, N. Faraz, A. Yildirim, and Q. Wu, “A series solution of the long porous slider,” Tribology Transactions, vol. 54, no. 2, pp. 187–191, 2011. 16 N. A. Khan, A. Ara, S. A. Ali, and A. Mahmood, “Analytical study of Navier-Stokes equation with fractional orders using He’s homotopy perturbation and variational iteration methods,” International Journal of Nonlinear Sciences and Numerical Simulation, vol. 10, no. 9, pp. 1127–1134, 2009. 17 H. Aminikhah and J. Biazar, “A new HPM for ordinary differential equations,” Numerical Methods for Partial Differential Equations, vol. 26, no. 2, pp. 480–489, 2010. 18 H. Aminikhah and M. Hemmatnezhad, “An efficient method for quadratic Riccati differential equation,” Communications in Nonlinear Science and Numerical Simulation, vol. 15, no. 4, pp. 835–839, 2010. 19 Y. Khan and N. Faraz, “Modified fractional decomposition method having integral w.r.t dξα ,” Journal of King Saud University—Science. In press. 20 A. S. Bataineh, M. S. M. Noorani, and I. Hashim, “Solving systems of ODEs by homotopy analysis method,” Communications in Nonlinear Science and Numerical Simulation, vol. 13, no. 10, pp. 2060–2070, 2008.