Volume 2020, Issue 1 4714032
Research Article
Open Access

Qualitative Analysis of Implicit Dirichlet Boundary Value Problem for Caputo-Fabrizio Fractional Differential Equations

Rozi Gul

Rozi Gul

Department of Mathematics, University of Malakand, Chakdara Dir(L), Pakistan uom.edu.pk

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Muhammad Sarwar

Corresponding Author

Muhammad Sarwar

Department of Mathematics, University of Malakand, Chakdara Dir(L), Pakistan uom.edu.pk

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Kamal Shah

Kamal Shah

Department of Mathematics, University of Malakand, Chakdara Dir(L), Pakistan uom.edu.pk

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Thabet Abdeljawad

Corresponding Author

Thabet Abdeljawad

Department of Mathematics and General Sciences, Prince Sultan University, P.O. Box 66833, Riyadh 11586, Saudi Arabia psu.edu.sa

Department of Medical Research, China Medical University, Taichung 40402, Taiwan cmu.edu.tw

Department of Computer Science and Information Engineering, Asia University, Taichung, Taiwan asia.edu.tw

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Fahd Jarad

Fahd Jarad

Department of Mathematics, Faculty of Arts and Sciences, Cankaya University, Ankara 06790, Turkey cankaya.edu.tr

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First published: 23 November 2020
Citations: 10
Academic Editor: Adrian Petrusel

Abstract

This article studies a class of implicit fractional differential equations involving a Caputo-Fabrizio fractional derivative under Dirichlet boundary conditions (DBCs). Using classical fixed-point theory techniques due to Banch’s and Krasnoselskii, a qualitative analysis of the concerned problem for the existence of solutions is established. Furthermore, some results about the stability of the Ulam type are also studied for the proposed problem. Some pertinent examples are given to justify the results.

1. Introduction and Preliminaries

The concerned area of fractional order differential equations (FODEs) have many concentrations in real-world problems and have paid close attention to numerous researchers in the past few decades [15]. The mentioned area has been studied from several aspects, such as the existence and uniqueness of solutions via using the classical fixed-point theory, the numerical analysis, the optimization theory, and also the theory of stability corresponding to various fractional differential operators like Caputo, Hamdard, and Riemann-Liouville (we refer few as [69]). In the aforementioned operators, there exists a singular kernel. Therefore, recently some authors introduced some new types of fractional derivative operators in which they have replaced a singular kernel by a nonsingular kernel. The nonsingular kernel derivative has been proved as a good tool to model real-world problems in different fields of science and engineering [10, 11]. In fractional, it is called nonsingular exponential type or Caputo-Fabrizio fractional differential (CFFD) operator. The CFFD operator introduced two researchers, Caputo and Fabrizio for the first time in 2015 [12]. They replaced the singular kernel in the usual Caputo and Riemann-Liouville derivative by an exponential nonsingular kernel. The new operator of this type was found to be more practical than the usual Caputo and Riemann-Liouville fractional differential operators in some problems (see some detailed references such as [1315]). Recently, many researchers have studied the existence and uniqueness of the solutions at the initial value problems for FODEs under the said operator. But the investigation has been limited to initial value problems only. On the other hand, boundary value problems have significant applications in engineering and other physical sciences during modeling numerous phenomena (we refer to see [1619]). Furthermore, during optimization and numerical analysis of the mentioned problems, researchers need stable results from theoretical as well as practical sides. A stable result may lead us to a stable process. Therefore, the stability theory has also got proper attention during the last many decades. It is well known fact that stability analysis plays an important role. Various stability concepts such as exponential stability, Mittag-Lefler stability and Hayers-Ulam’s stability have been adopted in literature to study the stability of different systems of FODEs. The analysis of Hyers-Ulam’s stability has been recognized as a simple form of investigation. For historical background on the stability of Hyers-Ulam, we refer to see previous articles [2023]. But recently, that type of problem has not been adequately studied for a new type of CFFD operator. Therefore, in this work, we will investigate an implicit class of FODEs involving the CFFD operator under DBCs
(1)
where  CFD is used for CFFD and I = [c, d], f : I × R × RR is a continuous function. In this article, we investigate uniqueness and existence of solutions to the proposed problem (1) by classical fixed-point theorems due to Banach’s and Krasnoselskii. Further, we investigate some pertinent analysis about the stability theory due to Ulam, and Hyers is investigated for the mentioned problem (1). For the authenticity of the presented work, two concrete examples are also studied.

Throughout the paper, C[I, R] is a Banach space with norm ‖z‖ = maxwI|z(w)|.

Definition 1 (see [24].)For any z(w) ∈ C[I, R], we defined the derivative of Caputo-Fabrizio for nonsingular kernel as

(2)
where D(μ) > 0 is the normalization function with D(0) = D(1) = 1 satisfying.

Definition 2 (see [24].)The integral of Caputo-Fabrizio for nonsingular kernel type is given by

(3)
where  CFI is used for Caputo-Fabrizio integral operator.

Definition 3 (see [25].)Let n < μn + 1 and f be such that f(n)H1(c, d). Set α = μn. Then, α ∈ [0, 1] and we define

(4)

Lemma 4. For z(w) defined on [c, d] and μ ∈ [n, n + 1], for some nN0, we have

(5)

2. Results and Discussion

In this part, we investigate the solution of the proposed problem (1) and also study the uniqueness and existence of the solutions.

Lemma 5. The solution of

(6)
is given by
(7)

Proof. Let z(w) be a solution to problem (6). Applying Caputo-Fabrizio integral on both sides and then using Lemma 4 and Definition 3, we have

(8)
which implies that
(9)

Using boundary conditions z(c) = z(d) = 0, we have

(10)

Putting c0, c1 in (9), we get

(11)

For simplification, use some notations; we use and give the solution of (1) as bellow.

Corollary 6. In view of 6, the solution of the considered problem (1) is given by

(12)

Further, for the existence and uniqueness of the solution of problem (1), we use some fixed point theorems. For this, we need to define an operator as N : C[I, R] → C[I, R] by

(13)

To proceed further, using Corollary (6) to convert the proposed problem (1) is to a fixed point problem as Nz(w) = z(w), where the operator N is given by (13). Therefore, Problem (1) has a solution if and only if the operator N has a fixed point, where λ(w) = f(w, z(w), λ(w)) and . We assume that

(H1) There exist certain constant Df > 0 and 0 < Ef < 1, such that

(14)
for all

Theorem 7. Under the hypothesis (H1), the mentioned problem (1) has a unique solution if

(15)

Proof. Suppose we have

(16)
where are given by λ(w) = f(w, z(w), λ(w)) and by using hypothesis (H1), we have
(17)

Repeating the above process, we get

(18)

Using (18) in (16), we have

(19)

Applying maximum on both sides, we have

(20)

Thus, operator N is a contraction; therefore, the operator N has a unique fixed point. Hence, the corresponding problem (1) has a unique solution.

Our next result is to show the existence of the solution to the proposed problem (1) which is based on Krasnoselskii’s fixed-point theorem. Therefore, the given hypothesis hold.

(H2) There exist constant pf, qf, rf > 0 with 0 < rf < 1 such that
(21)

Theorem 8 (see [26].)Let HC[I, R] be a closed, convex nonempty subset of C[I, R]; then, there exist N1, N2 operators such that

  • (1)

    N1z1 + N2z2H for all z1, z2H

  • (2)

    N1 is a contraction, and N2 is compact and continuous

Then, there exist at least one solution zH such that N1z + N2z = z.

Theorem 9. If the hypothesis (H2) is satisfied, then (1) has at least one solution if

(22)

Proof. Suppose we define two operators from (13) as

(23)

Let us define a set F = {zC[I, R]: ∥z∥≤r}, since f is continuous, so we show that the operator N1 is contraction. For this we have

(24)
using (18), and then taking the maximum on both sides, we have
(25)

Hence, N1 is contraction. Next, to prove that the operator N2 is compact and continuous, for this z(w) ∈ C[I, R], we have

(26)
where λ(w) ∈ R, λ(w) = f(w, z(w), λ(w)); now, using hypothesis (H2), we have
(27)
repeating the above process, so we get
(28)

Now, using (28) in (26) and then taking the maximum on both sides, we have

(29)

Which implies that

(30)

Therefore, N2 is bounded. Next, let w1 < w2 in I, we have

(31)

Now, using (28) in (31), we have

(32)

Applying maximum on right-hand side of the above inequality, we take

(33)

Obviously, from (33), we see that w1w2; then, the right-hand side of (33) goes to zero, so ∣N2z(w2) − N2z(w1) | →0 as w1w2. Hence, the operator N2 is continuous. Also, N(H) ⊂ H; therefore, the operator N2 is compact, and by the Arzela-Ascoli theorem, the operator N has at least one fixed point. Therefore, the mentioned problem (1) has at least one solution.

3. Stability Theory

In this portion, we develop several consequences concerning the stability of Hyers-Ulam and generalize Hyers-Ulam type. Before progressing further, we provide various notions and definitions:

Definition 10. The proposed problem (1) is Hyers-Ulam stable if at any ε > 0 for the given inequality

(34)
there exist a unique solution with a constant Kf such that
(35)

Further, the considered problem (1) will generalize Hyers-Ulam stable if there exists nondecreasing function ϕ : (c, d) → (0, ∞) such that

(36)
with ϕ(c) = 0 and ϕ(d) = 0.

Also, we state an important remark as:

Remark 11. Let there exist a function ψ(w) which depends on zC[I, R] with ψ(c) = 0 and ψ(d) = 0 such that

(37)

Lemma 12. The solution of the given proposed problem

(38)
is
(39)
where Gμ = (2 − μ)/D(μ − 1), , and λ(w) = f(w, z(w), λ(w)). Moreover, the solution of the given inequality, we have
(40)

Proof. The solution of (39) can be acquired straightforward by using Lemma 5. Although from the solution, it is clear to become result (40) by using Remark 11.

Theorem 13. Under the Lemma 12, the solution of the proposed problem (1) is Hyers-Ulam stable and also generalized Hyers-Ulam stable if

Proof. Let z(w) ∈ C[I, R] be any solution of the considered problem (1) and be a unique solution of the said problem; then, we take,

(41)

Using (40) and (18) in the above inequality, then taking maximum on both sides, we have

(42)

Hence, from the above inequality, we have

(43)

Therefore, the solution is Hyers-Ulam stable. Further, let

(44)
and there exist nondecreasing function ϕC((c, d), (0, ∞)). Then, from (43) we can write as
(45)

4. Examples of Our Analysis

In this part of our analysis, we justify certain obtained results through some counter examples which are given below.

Example 14. Suppose, we take the boundary value problem of implicit type as

(46)

Clearly, c = 0, d = 1 and is a continuous function for all x ∈ [0, 1]. Further, suppose that ; then, we consider as

(47)

which implies that

(48)

Since from (48), one has Df = 1/55, Ef = 1/55, and μ = 1/3. Further, also consider

(49)

Therefore, pf = 1/35, qf = 1/55, rf = 1/55. and Gμ = 1/3, , c = 0, and d = 1. Then

(50)

Therefore, the conditions of Theorem 7 are satisfied. Thus, the problem (46) has a unique solution. Further, we need to satisfy some conditions of theorem (9).

(51)

Hence, the conditions of Theorem 9 also hold. Therefore, (46) has at least one solution. Furthermore, proceed to verify the stability results; we see that

(52)

Hence, the solution of the mentioned problem (46) is Hyers-Ulam stable and consequently generalized Hyers-Ulam stable.

Example 15. Take another boundary value problem of implicit type as

(53)

Clearly c = 0, d = 1 and is a continuous function for all w ∈ [0, 1]. Further let , then consider, we have

(54)
which implies that the maximum on right side to the above inequality, we have
(55)

Thus from (55), one has Df = 1/45, Ef = 3/65, and μ = 3/7. And also consider we have

(56)
where pf = 1/15, qf = 1/45, rf = 3/65, and then Gμ = 1/200, . Then
(57)

Therefore, the conditions of Theorem 7 are satisfied. Thus, the problem (53) has a unique solution. Further, we need to satisfy some conditions of Theorem (9), we have

(58)

Hence, the conditions of Theorem (9) also hold. Therefore, (53) has at least one solution. Furthermore, proceed to verify stability results; we see that

(59)

Hence, the solution of the mentioned problem (53) is Hyers-Ualm stable and consequently generalized Hyers-Ulam stable.

5. Conclusion

We have successfully attained several essential conditions consistent to existence theory and stability theory for implicit type problem of DBCs with involving Caputo-Fabrizio fractional operator. By classical fixed point theory, we used some fixed point theorem like Krasnoselskii’s fixed-point and Banach’s contraction. Further, we studied certain stability results of Hyers-Ulam and generalized Hyers-Ulam stability. By appropriate illustrations, we have established the obtained investigation.

Conflicts of Interest

The authors declare that they have no competing interest regarding this manuscript.

Authors’ Contributions

All authors contribute equally to the writing of this manuscript. All authors read and approve the final version.

Acknowledgments

The authors are grateful to the editorial board and anonymous reviewers for their comments and remarks which helped to improve this manuscript. The third author would like to thank Prince Sultan University for funding this work through research group Nonlinear Analysis Methods in Applied Mathematics (NAMAM) group number RG-DES-2017-01-17.

    Data Availability

    No data were used to support this study.

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