Existence and Uniqueness Results for the Coupled Pantograph System With Caputo Fractional Operator and Hadamard Integral
Abstract
The main objective of this research involves studying a new novel coupled pantograph system with fractional operators together with nonlocal antiperiodic integral boundary conditions. The system consists of nonlinear pantograph fractional equations which integrate with Caputo fractional operators and Hadamard integrals. A fixed-point approach has served to study both existence and uniqueness aspects of solutions for the proposed model. The paper investigates Hyers–Ulam stability properties of the developed solution. An appropriate example was provided to confirm the theoretical findings.
1. Introduction
Recent studies have shown that some real-world processes cannot be effectively described by classical differential equations formulated using standard derivatives and integrals, integer order ordinary DEs or partial . Fractional calculus is a powerful tool for simulating these complex processes, since it extends the idea of integer order to arbitrary order. Due to its numerous applications across a variety of scientific domains, fractional calculus has attracted a lot of attention during the past few decades. It has been applied to a variety of scientific disciplines, including polymer rheology, biology, capacitor theory, the blood-Bow phenomenon, nonlinear seismic oscillation, image processing, aerodynamics, geophysics, and electrical circuits. We cite some publications [1–4] for other applications of fractional DEs .
Among the most famous equations, there is the pantograph equation, for which we can state that the pantograph phenomenon is an essential component of electric trains which collects electrical current from overload lines. This equation has been modeled by Ockendon and Tayler [5]. In recent years, many researchers have proposed several fractional variants of the above pantograph equation. For more details, see for instance the research works [6–17] and references therein the evolution of physical events in an environment that is fluctuating is described by the pantograph equation. On the other side, in recent years, we have seen comprehensive discussions on FDEs with different boundary conditions [18–27]. In between, many researchers have conducted an analysis on dynamics of the LE. Yu et al. [28] examine the existence results obtained using the fixed point criteria for in the Langevin settings with various types of boundary conditions. By employing upper and lower solution technique analyses, Baghani et al. [29] connected some results for coupled Langevin systems with various forms of boundary conditions. Discussion on with nonlocal fractional boundary conditions is provided by Fazli and Nieto [30] in 2018.
The rest of the paper is organized as follows. Basic definitions and lemmas are found in Section 2. Section 3 contains the existence and uniqueness of the solution to the considered problem. -stability of the solution is discussed in the next section. We propose an application to provide a more transparent result in Section 5.
2. Preliminaries
First of all, the aim of this section is to present some important basics that help the readers in understanding our study.
Definition 1 (see [2].)Let be a continuous and integrable function , then the Hadamard integral of fractional order σ > 0 is defined as
Definition 2 (see [2].)Let be a , σ ≥ 0 and . The Hadamard derivative of fractional order σ is described as
Definition 3 (see [2].)Let be a -times continuously differentiable function. The Caputo derivative of order σ > 0 is formulated as
Lemma 1 (see [2].)Suppose that ϰ > 0, κ = [Re(ϰ)] + 1 and Re(κ) > 0, then
The next theorem is a fixed point criterion for proving our main existence theorem.
Theorem 1 (see [2].)Assume that Δ ≠ ∅ is a convex, closed and bounded set in a Banach space Ξ. Assume also that Ω1, Ω2 : Δ⟶Ξ are operators such that
- 1.
for ϱ, ϑ ∈ Δ, Ω1ϱ + Ω2ϑ ∈ Δ;
- 2.
Ω2 is contraction;
- 3.
Ω2 is compact and continuous.
Then, ∃ϱ∗ ∈ Δ such that ϱ∗ = Ω1ϱ∗ + Ω2ϱ∗.
3. Existence and Uniqueness Results
We begin this part with the proof of an auxiliary lemma which gives us the main integral form of the solutions of the coupled pantograph system of equation (1).
Lemma 2. Assume that and the BVP including the coupled pantograph fractional is given by equation (1). Then the form of the solution to problem equation (1) is
Proof 1. Applying to both sides of the first equation of (1), one can get
Applying boundary conditions , we obtain that
Assume that is the space of all continuous functions from to . Define the space Θ = {ϱ(ν) : ϱ(ν) ∈ ℧} equipped with . Also, consider Υ = {ϑ(ν) : ϑ(ν) ∈ ℧} equipped with . Obviously, both (Θ, ‖·‖) and (Υ, ‖·‖) are Banach spaces. Clearly, the product (Θ × Υ, ‖·‖) is a Banach space endowed with ‖(ϱ, ϑ)‖ = ‖ϱ‖ + ‖ϑ‖.
Thus, the existence of the solution for the nonlinear coupled pantograph system (1) is limited to finding the fixed point of equation (12).
-
(S1) is continuous.
-
(S2) For all , and , there exist constants such that
() -
(S3) For , there exist such that
() -
(S4) For all , there exist such that
()
We now turn to the uniqueness property for solutions of the nonlinear coupled pantograph system (1).
Theorem 2. Suppose that (S1)-(S4) to be held and if h < 1. Then the nonlinear coupled pantograph system (1) has a unique solution, where
Proof 2. Let be closed bounded and convex subsets of Θ × Υ, where
Now, we have
In the same manner, we obtain
From equations (22) and (23), we obtain
Hence, . Finally, for completing the next part of the proof, for each , we have
Similarly,
Therefore,
Since h < 1, then Ω is a contraction. Consequently, an operator Ω has a unique fixed point when utilizing the Banach contraction theorem. Therefore, there is a unique solution to the nonlinear coupled pantograph system (1).
Now, everything is ready to turn to the main existence theorem.
Theorem 3. Assume that the hypotheses (S1)-(S3) hold, then there exists at least one solution to the nonlinear coupled pantograph system (1) on if h5 < 1, where h5 = max{h3, h4}.
Proof 3. Let be closed bounded and convex subsets of Θ × ϒ, where
We split the proof into the following steps:
-
Step 1: We shall show that , for all . For this,
() -
In the same manner, we obtain
() -
From equations (35) and (36), we obtain
() -
Step 2: Ω∗ is contraction: For this regard, let . We have
() -
where
() -
which implies that
() -
Similarly, we can prove that
() -
where
() -
Therefore,
() -
it follows that
() -
Since h5 < 1, then Ω∗ is a contraction.
-
Step 3: Ω is continuous and compact: Since , then it is continuous on . Hence, Ω is continuous. To show that Ω is compact, it is sufficient to claim that Ω is relatively compact and uniformly bounded on . Now, for , we have
()
Similarly, we can write
It follows from equations (45) and (46) that Ω is uniformly bounded on . Consider
From Lagrange mean value theorem, we can write
By the same technique, we have
Therefore, Ω is equicontinuous. Thank to Arzela–Ascoli theorem, Ω is compact on . This completes condition (3) in Theorem 1. Thus, there exists at least one solution to the nonlinear coupled pantograph system (1).
4. Stability Analysis
The -stability of the nonlinear coupled pantograph system (1) will be discussed in this step. First, the -stability of the considered nonlinear coupled pantograph system is defined as follows.
Definition 4. The solution of the nonlinear coupled pantograph system (1) is called -stable if such that for every and (ϱ, ϑ) ∈ ℧×℧ as a solution to the system
Remark 1. The pair (ϱ, ϑ) ∈ ℧×℧ is called a solution to the nonlinear coupled pantograph system (1) if and only if there exist such that for all ,
- i.
and ;
- ii.
,
- iii.
.
Lemma 3. Based on Remark 1, for each , the solution of the system
Proof 4. From Lemma 2, the desired relations are proved.
Theorem 4. If the assumptions (S1)-(S3) hold, then the solution to the nonlinear coupled pantograph system (1) is -stable if
Proof 5. Thank to Lemma 3, if (ϱ, ϑ) is a solution to equation (52), and is a solution to equation (1), then, we get
Therefore,
Hence,
Setting ∇1 = (2b1ζΛ/1 − (2b1ζΛ + b2)) and ∇2 = (b3/1 − (2b1ζΛ + b2))), we can write the above inequality as
Similarly, we have
The inequalities equations (65) and (66) can be written as
Using the inverse of the matrix, we get
Let us consider and
Putting
5. An Application
This part is devoted to presenting an illustrative example in the form of the given nonlinear coupled pantograph system to support the results.
Example 1. Consider the nonlinear coupled pantograph system
6. Conclusion
In some applicable areas of sciences like physics, chemistry, and electrical engineering, fractional pantograph have been an important subject. Many researchers substituted FDEs instead of the standard classical DEs in order to reduce noise and staircase effects. Therefore, in this paper, by defining a coupled system of such pantograph in its fractional form, we discussed on some qualitative properties. With the help of the Krasnoselskii’s fixed point theorem and the Banach principle, the existence and uniqueness results of the pantograph fractional DEs have been investigated under the Caputo derivatives. Despite the current interest in the topic of FDEs with boundary conditions, no articles specifically addressing this type of combined coupled pantograph system have been published. Stability property was also checked completely in relation to the solutions of the mentioned system. An application that describes and illustrates the validity of the results was provided as a numerical example.
Conflicts of Interest
The authors declare no conflicts of interest.
Funding
No financial support was received.
Open Research
Data Availability Statement
No data were used for the research described in this article.