Abstract
In this paper, by applying the technique of measure of weak noncompactness and Mönch’s fixed point theorem, we investigate the existence of weak solutions under the Pettis integrability assumption for a coupled system of Hadamard fractional differential equations.
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1 Introduction
Fractional differential equations have recently been applied in various areas of engineering, mathematics, physics and bio-engineering, and other applied sciences [1, 2]. There has been a significant development in fractional differential and integral equations in recent years; see the monographs of Abbas et al. [3, 4], Kilbas et al. [5], and the papers [6–20].
The measure of weak noncompactness was introduced by De Blasi [21]. The strong measure of noncompactness was considered by Banas̀ and Goebel [22] and subsequently developed and used in many papers; see, for example, Akhmerov et al. [23], Alvàrez [24], Benchohra et al. [25], Guo et al. [26], and the references therein. In [25, 27] the authors considered some existence results by applying the techniques of the measure of noncompactness. Recently, several researchers obtained other results by application of the technique of measure of weak noncompactness; see [4, 28, 29] and the references therein.
In this paper, we discuss the existence of weak solutions to the following coupled system of Hadamard fractional differential equations:
with the following initial conditions:
where \(T>1\), \(r,\rho\in(0,1]\), \(\phi,\psi\in E\), \(f_{1},f_{2}:I \times E\times E\rightarrow E\) are given continuous functions, E is a real (or complex) Banach space with norm \(\Vert \cdot \Vert _{E}\) and dual \(E^{*}\) such that E is the dual of a weakly compactly generated Banach space X, \({}^{H}I_{1}^{r}\) is the left-sided mixed Hadamard integral of order r, and \({}^{H}D_{1}^{r}\) is the Hadamard fractional derivative of order r.
2 Preliminaries
Let C be the Banach space of all continuous functions w from I into E with the supremum (uniform) norm
As usual, \(\operatorname {AC}(I)\) denotes the space of absolutely continuous functions from I into E. By \(C_{r,\ln}(I)\), we denote the weighted space of continuous functions defined by
with the norm
We denote \(\Vert w\Vert _{C_{r,\ln}}\) by \(\Vert w\Vert _{C_{r}}\). Also, by \(\mathcal{C}_{r,\rho,\ln}(I):=C_{r,\ln}(I)\times C_{\rho,\ln}(I)\) we denote the product weighted space with the norm
In the following we denote \(\Vert (u,v)\Vert _{\mathcal {C}_{r,\rho,\ln}(I)} \) by \(\Vert (u,v)\Vert _{\mathcal{C}}\).
Let \((E,w)=(E,\sigma(E,E^{*}))\) be the Banach space E with its weak topology.
Definition 2.1
A Banach space X is called weakly compactly generated (WCG for short) if it contains a weakly compact set whose linear span is dense in X.
Definition 2.2
A function \(h:E\rightarrow E\) is said to be weakly sequentially continuous if h takes each weakly convergent sequence in E to a weakly convergent sequence in E (i.e., for any \((u_{n})\) in E with \(u_{n}\rightarrow u\) in \((E,w)\) then \(h(u_{n})\rightarrow h(u)\) in \((E,w)\)).
Definition 2.3
([30])
The function \(u:I\rightarrow E\) is said to be Pettis integrable on I if and only if there is an element \(u_{J}\in E\) corresponding to each \(J\subset I\) such that \(\phi(u_{J})=\int_{J} \phi(u(s))\,ds\) for all \(\phi\in E^{\ast}\), where the integral on the right-hand side is assumed to exist in the sense of Lebesgue (by definition, \(u_{J}=\int_{J}u(s)\,ds\)).
Let \(P(I,E)\) be the space of all E-valued Pettis integrable functions on I, and \(L^{1}(I,E)\) be the Banach space of Lebesgue integrable functions \(u:I\to E\). Define the class \(P_{1}(I,E)\) by
The space \(P_{1}(I,E) \) is normed by
where λ stands for a Lebesgue measure on I.
The following result is due to Pettis (see [30], Theorem 3.4 and Corollary 3.41).
Proposition 2.4
([30])
If \(u\in P_{1}(I,E)\) and h is a measurable and essentially bounded E-valued function, then \(uh\in P_{1}(J,E)\).
For all that follows, the symbol “∫” denotes the Pettis integral.
Let us recall some definitions and properties of Hadamard fractional integration and differentiation. We refer to [5, 31] for a more detailed analysis.
Definition 2.5
The Hadamard fractional integral of order \(q>0\) for a function \(g\in L^{1}(I,E)\) is defined as
provided the integral exists, where \(\Gamma(\cdot)\) is the (Euler’s) gamma function defined by
Example 2.6
Let \(0< q<1\). Then
Remark 2.7
Let \(g\in P_{1}([1,T], E)\). For every \(\varphi\in E^{*}\), we have
Analogous to the Riemann-Liouville fractional calculus, the Hadamard fractional derivative is defined in terms of the Hadamard fractional integral in the following way. Set
where \([q]\) is the integer part of q, and
Definition 2.8
The Hadamard fractional derivative of order q applied to the function \(w\in \operatorname {AC}_{\delta}^{n}\) is defined as
Example 2.9
Let \(0< q<1\). Then
It has been proved (see, e.g., Kilbas [32], Theorem 4.8) that in the space \(L^{1}(I,E)\), the Hadamard fractional derivative is the left-inverse operator to the Hadamard fractional integral, i.e.,
From Theorem 2.3 of [5], we have
Corollary 2.10
Let \(h:I\to E\) be a continuous function. A function \(w\in L^{1}(I,E)\) is said to be a solution of the equation
if and only if u satisfies the following Hadamard integral equation:
Definition 2.11
([21])
Let E be a Banach space, \(\Omega_{E}\) be the bounded subsets of E, and \(B_{1}\) be the unit ball of E. The De Blasi measure of weak noncompactness is the map \(\beta:\Omega_{E}\rightarrow[0, \infty)\) defined by
The De Blasi measure of weak noncompactness satisfies the following properties:
-
(a)
\(A\subset B\Rightarrow\beta(A)\leq\beta(B)\),
-
(b)
\(\beta(A)= 0 \Leftrightarrow A \) is weakly relatively compact,
-
(c)
\(\beta(A\cup B)=\max\{\beta(A), \beta(B)\}\),
-
(d)
\(\beta(\overline{A}^{\omega})=\beta(A)\) (\(\overline{A} ^{\omega}\) denotes the weak closure of A),
-
(e)
\(\beta(A+B)\leq\beta(A)+\beta(B)\),
-
(f)
\(\beta(\lambda A)=\vert \lambda \vert \beta(A)\),
-
(g)
\(\beta(\operatorname {conv}(A))=\beta(A)\),
-
(h)
\(\beta(\bigcup _{\vert \lambda \vert \leq h} \lambda A)= h \beta(A)\).
The next result follows directly from the Hahn-Banach theorem.
Proposition 2.12
Let E be a normed space, and \(x_{0}\in E\) with \(x_{0}\neq0\). Then there exists \(\varphi\in E^{\ast}\) with \(\Vert \varphi \Vert =1\) and \(\varphi(x_{0})=\Vert x_{0}\Vert \).
For a given set V of functions \(v: I\to E\), let us denote
and
Lemma 2.13
([26])
Let \(H\subset C\) be a bounded and equicontinuous subset. Then the function \(t\to\beta(H(t))\) is continuous on I, and
and
where \(H(s)=\{u(s):u\in H, s\in I\}\), and \(\beta_{C}\) is the De Blasi measure of weak noncompactness defined on the bounded sets of C.
For our purpose, we will need the following fixed point theorem.
Theorem 2.14
([33])
Let Q be a nonempty, closed, convex, and equicontinuous subset of a metrizable locally convex vector space \(C(J, E)\) such that \(0\in {Q}\). Suppose \(T:Q\rightarrow Q\) is weakly-sequentially continuous. If the implication
holds for every subset \(V\subset Q\), then the operator T has a fixed point.
3 Existence of weak solutions
Let us start by defining what we mean by a weak solution of the coupled system (1)-(2).
Definition 3.1
By a weak solution of the coupled system (1)-(2), we mean measurable coupled functions \((u,v)\in{\mathcal{C}}_{r,\rho,\ln}\) satisfying conditions (2) and equations (1) on I.
The following hypotheses will be used in the sequel.
- \((H_{1})\) :
-
For a.e. \(t\in I\), the functions \(v\to f_{i}(t,v, \cdot)\), \(i=1,2\), and \(w\to f_{i}(t,\cdot,w)\), \(i=1,2\), are weakly sequentially continuous;
- \((H_{2})\) :
-
For each \(v,w\in E\), the function \(t\to f(t,v,w)\) is Pettis integrable a.e. on I;
- \((H_{3})\) :
-
There exists \(p_{i}\in C(I,[0,\infty))\), \(i=1,2\), such that for all \(\varphi\in E^{*}\), we have
$$ \bigl\vert \varphi\bigl(f_{i}(t,u,v)\bigr)\bigr\vert \leq \frac{p_{i}(t)\Vert \varphi \Vert }{1+\Vert \varphi \Vert +\Vert u\Vert _{E}+\Vert v\Vert _{E}} \quad\text{for a.e. } t\in I\text{ and each } u,v\in E; $$ - \((H_{4})\) :
-
For each bounded and measurable set \(B\subset E\) and for each \(t\in I\), we have
$$ \beta\bigl(f_{i}(t,B,B)\bigr)\leq(\ln t)^{1-r}p_{i}(t) \beta(B), \quad i=1,2. $$
Set
Theorem 3.2
Assume that hypotheses \((H_{1})\)-\((H_{4})\) hold. If
then the coupled system (1)-(2) has at least one weak solution defined on I.
Proof
Define the operators \(N_{1}:C_{r,\ln}\rightarrow C_{r,\ln}\) and \(N_{2}:C_{\rho,\ln}\rightarrow C_{\rho,\ln}\) by
and
Consider the continuous operator \(N:\mathcal{C}_{r,\rho,\ln}\to {\mathcal{C}} _{r,\rho,\ln}\) defined by
First notice that the hypotheses imply that the functions \(t\mapsto ( \ln\frac{t}{s} ) ^{r-1}\frac{f_{1}(s,u(s),v(s))}{s}\) and \(t\mapsto ( \ln\frac{t}{s} ) ^{\rho-1} \frac{f_{2}(s,u(s),v(s))}{s}\), for a.e. \(t\in I\), are Pettis integrable, and for each \((u,v)\in{\mathcal{C}}_{r,\rho,\ln}\), the function \(t\mapsto f(t,u(t),v(t))\) is Pettis integrable over I. Thus, the operator N is well defined. Let \(R>0\) be such that
and consider the set
Clearly, the subset Q is closed, convex, and equicontinuous. We shall show that the operator N satisfies all the assumptions of Theorem 2.14. The proof will be given in several steps.
Step 1. N maps Q into itself.
Let \((u,v)\in Q\), \(t\in I\), and assume that \((N_{i}u)(t)\neq0\), \(i=1,2\). Then there exists \(\varphi\in E^{*}\) such that \(\Vert (\ln t)^{1-r}(N _{i}u)(t)\Vert _{E}=\varphi(|(\ln t)^{1-r}(N_{i}u)(t)|)\). Thus
Then
Again, we get
Thus, we obtain
Next, let \(t_{1},t_{2}\in I\) such that \(t_{1}< t_{2}\), and let \((u,v)\in Q\), with
and
Then there exists \(\varphi\in E^{*}\) with \(\Vert \varphi \Vert =1\) such that
and
Then
This gives
Thus, we get
Also, we can obtain that
Hence \(N(Q)\subset Q\).
Step 2. N is weakly-sequentially continuous.
Let \((u_{n},v_{n})\) be a sequence in Q, and let \((u_{n}(t),v_{n}(t)) \to(u(t),v(t))\) in \((E,\omega)\times(E,\omega)\) for each \(t\in I\). Fix \(t\in I\), since for any \(i\in\{1,2\}\) the function \(f_{i}\) satisfies assumption \((H_{1})\), we have \(f_{i}(t,u_{n}(t),v _{n}(t))\) converges weakly uniformly to \(f(t,u(t),v(t))\). Hence the Lebesgue dominated convergence theorem for Pettis integral implies that \(((N_{1}u_{n})(t),(N_{2}v_{n})(t))\) converges weakly uniformly to \(((N_{1}u)(t),(N_{2}v)(t))\) in \((E,\omega)\times(E,\omega)\) for each \(t\in I\). Thus, \(N(u_{n},v_{n})\to(N(u),N(v))\). Hence, \(N:Q\to Q\) is weakly-sequentially continuous.
Step 3. Implication ( 3 ) holds.
Let V be a subset of Q such that \(\overline{V}=\overline{\operatorname {conv}}(N(V) \cup\{0\})\). Obviously
Further, as V is bounded and equicontinuous, by Lemma 3 in [34] the function \(t\to v(t)=\beta(V(t))\) is continuous on I. From \((H_{3})\), \((H_{4})\), Lemma 2.13 and the properties of the measure β, for any \(t\in I\), we have
Thus
From (4), we get \(\Vert v\Vert _{\mathcal{C}}=0\), that is, \(v(t)=\beta(V(t))=0\) for each \(t\in I\). And then, by Theorem 2 in [35], V is weakly relatively compact in \([\mathcal {C}]_{r,\rho, \ln}\). Applying now Theorem 2.14, we conclude that N has a fixed point which is a weak solution of the coupled system (1)-(2). □
4 An example
Let
be the Banach space with the norm
We consider the following coupled system of Hadamard fractional differential equations:
with the initial conditions
where
and
with
Set
Clearly, the functions f and g are continuous. For each \(u,v\in E\) and \(t\in[1,e]\), we have
and
Hence, hypothesis \((H_{3})\) is satisfied with \(p_{1}^{*}=p_{2}^{*}=ce ^{-4}\). We shall show that condition (4) holds with \(T=e\). Indeed,
Simple computations show that all conditions of Theorem 3.2 are satisfied. It follows that the coupled system (8)-(9) has at least one solution on \([1,e]\).
References
Hilfer, R: Applications of Fractional Calculus in Physics. World Scientific, Singapore (2000)
Tarasov, VE: Fractional Dynamics: Application of Fractional Calculus to Dynamics of Particles, Fields and Media. Springer, Heidelberg (2010)
Abbas, S, Benchohra, M, N’Guérékata, GM: Topics in Fractional Differential Equations. Springer, New York (2012)
Abbas, S, Benchohra, M, N’Guérékata, GM: Advanced Fractional Differential and Integral Equations. Nova Science Publishers, New York (2015)
Kilbas, AA, Srivastava, HM, Trujillo, JJ: Theory and Applications of Fractional Differential Equations. Elsevier, Amsterdam (2006)
Ahmad, B, Alsaedi, A, Kirane, M, Tapdigoglu, RG: An inverse problem for space and time fractional evolution equations with an involution perturbation. Quaest. Math. 40(2), 151-160 (2017)
Abbas, S, Benchohra, M: Fractional order integral equations of two independent variables. Appl. Math. Comput. 227, 755-761 (2014)
Abbas, S, Benchohra, M, Henderson, J: Partial Hadamard fractional integral equations. Adv. Dyn. Syst. Appl. 10(2), 97-107 (2015)
Ahmad, B, Alsaedi, A, Kirane, M: Nonexistence results for the Cauchy problem of time fractional nonlinear systems of thermoelasticity. Math. Methods Appl. Sci. 40, 4272-4279 (2017)
Thiramanus, P, Ntouyas, SK, Tariboon, J: Existence and uniqueness results for Hadamard-type fractional differential equations with nonlocal fractional integral boundary conditions. Abstr. Appl. Anal. 2014, 902054 (2014)
Wang, JR, Feckan, M, Zhou, Y: A survey on impulsive fractional differential equations. Fract. Calc. Appl. Anal. 19, 806-831 (2016)
Wang, JR, Feckan, M, Zhou, Y: Center stable manifold for planar fractional damped equations. Appl. Math. Comput. 296, 257-269 (2017)
Zhou, Y: Attractivity for fractional differential equations. Appl. Math. Lett. 75, 1-6 (2018)
Zhou, Y, Peng, L: Weak solutions of the time-fractional Navier-Stokes equations and optimal control. Comput. Math. Appl. 73, 1016-1027 (2017)
Zhou, Y, Peng, L: On the time-fractional Navier-Stokes equations. Comput. Math. Appl. 73, 874-891 (2017)
Zhou, Y, Vijayakumar, V, Murugesu, R: Controllability for fractional evolution inclusions without compactness. Evol. Equ. Control Theory 4, 507-524 (2015)
Zhou, Y, Zhang, L: Existence and multiplicity results of homoclinic solutions for fractional Hamiltonian systems. Comput. Math. Appl. 73, 1325-1345 (2017)
Zhou, Y, Zhang, L, Shen, XH: Existence of mild solutions for fractional evolution equations. J. Integral Equ. Appl. 25, 557-586 (2013)
Zhou, Y, Ahmad, B, Alsaedi, A: Existence of nonoscillatory solutions for fractional neutral differential equations. Appl. Math. Lett. 72, 70-74 (2017)
Zhou, Y, Peng, L, Ahmad, B, Alsaedi, A: Topological properties of solution sets of fractional stochastic evolution inclusions. Adv. Differ. Equ. 2017(1), 90 (2017)
De Blasi, FS: On the property of the unit sphere in a Banach space. Bull. Math. Soc. Sci. Math. Roum. 21, 259-262 (1977)
Banas̀, J, Goebel, K: Measures of Noncompactness in Banach Spaces. Dekker, New York (1980)
Akhmerov, RR, Kamenskii, MI, Patapov, AS, Rodkina, AE, Sadovskii, BN: Measures of Noncompactness and Condensing Operators. Birkhäuser, Basel (1992)
Alvàrez, JC: Measure of noncompactness and fixed points of nonexpansive condensing mappings in locally convex spaces. Rev. R. Acad. Cienc. Exactas Fís. Nat. Madr. 79, 53-66 (1985)
Benchohra, M, Henderson, J, Seba, D: Measure of noncompactness and fractional differential equations in Banach spaces. Commun. Appl. Anal. 12(4), 419-428 (2008)
Guo, D, Lakshmikantham, V, Liu, X: Nonlinear Integral Equations in Abstract Spaces. Kluwer Academic, Dordrecht (1996)
O’Regan, D: Weak solutions of ordinary differential equations in Banach spaces. Appl. Math. Lett. 12, 101-105 (1999)
Benchohra, M, Graef, J, Mostefai, F-Z: Weak solutions for boundary-value problems with nonlinear fractional differential inclusions. Nonlinear Dyn. Syst. Theory 11(3), 227-237 (2011)
Benchohra, M, Henderson, J, Mostefai, F-Z: Weak solutions for hyperbolic partial fractional differential inclusions in Banach spaces. Comput. Math. Appl. 64, 3101-3107 (2012)
Pettis, BJ: On integration in vector spaces. Trans. Am. Math. Soc. 44, 277-304 (1938)
Hadamard, J: Essai sur l’étude des fonctions données par leur développment de Taylor. J. Pure Appl. Math. 4(8), 101-186 (1892)
Kilbas, AA: Hadamard-type fractional calculus. J. Korean Math. Soc. 38(6), 1191-1204 (2001)
O’Regan, D: Fixed point theory for weakly sequentially continuous mapping. Math. Comput. Model. 27(5), 1-14 (1998)
Bugajewski, D, Szufla, S: Kneser’s theorem for weak solutions of the Darboux problem in a Banach space. Nonlinear Anal. 20(2), 169-173 (1993)
Mitchell, AR, Smith, Ch: Nonlinear equations in abstract spaces. In: Lakshmikantham, V (ed.) An Existence Theorem for Weak Solutions of Differential Equations in Banach Spaces, pp. 387-403. Academic Press, New York (1978)
Acknowledgements
The work was supported by the National Natural Science Foundation of China (No. 11671339).
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Abbas, S., Benchohra, M., Zhou, Y. et al. Weak solutions for a coupled system of Pettis-Hadamard fractional differential equations. Adv Differ Equ 2017, 332 (2017). https://doi.org/10.1186/s13662-017-1391-z
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DOI: https://doi.org/10.1186/s13662-017-1391-z