Loading [MathJax]/jax/output/SVG/jax.js
Research article

The heterogeneous linkage of economic policy uncertainty and oil return risks

  • The recent financial crisis and its aftermath boost the research of economic policy uncertainty and its relevant topics. In this paper, we forecast the oil return risks based on the CAViaR method and further depict the dynamic and heterogeneous features during the crisis (or non-crisis) period, as well as in different markets via DCC-GARCH models. The empirical results show the linkage of economic policy uncertainty and oil return risks, indicating an increasing trend and stronger relationship with major events. Further study shows the heterogeneous feature existing during crisis or non-crisis period, and there is heterogeneity in values and variations of their linkage in different markets. Therefore, policymakers should intervene timely in the crude oil market, release good news, and stabilize oil prices during the crisis period. During the non-crisis period, however, investors need to rationally analyze the price trend of the oil market, thereby preventing possible risks in the market.

    Citation: Hao Dong, Yue Liu, Jiaqi Chang. The heterogeneous linkage of economic policy uncertainty and oil return risks[J]. Green Finance, 2019, 1(1): 46-66. doi: 10.3934/GF.2019.1.46

    Related Papers:

    [1] Yousef Jawarneh, Humaira Yasmin, Abdul Hamid Ganie, M. Mossa Al-Sawalha, Amjid Ali . Unification of Adomian decomposition method and ZZ transformation for exploring the dynamics of fractional Kersten-Krasil'shchik coupled KdV-mKdV systems. AIMS Mathematics, 2024, 9(1): 371-390. doi: 10.3934/math.2024021
    [2] Ihsan Ullah, Aman Ullah, Shabir Ahmad, Hijaz Ahmad, Taher A. Nofal . A survey of KdV-CDG equations via nonsingular fractional operators. AIMS Mathematics, 2023, 8(8): 18964-18981. doi: 10.3934/math.2023966
    [3] Rasool Shah, Abd-Allah Hyder, Naveed Iqbal, Thongchai Botmart . Fractional view evaluation system of Schrödinger-KdV equation by a comparative analysis. AIMS Mathematics, 2022, 7(11): 19846-19864. doi: 10.3934/math.20221087
    [4] Aslı Alkan, Halil Anaç . The novel numerical solutions for time-fractional Fornberg-Whitham equation by using fractional natural transform decomposition method. AIMS Mathematics, 2024, 9(9): 25333-25359. doi: 10.3934/math.20241237
    [5] Maysaa Al-Qurashi, Saima Rashid, Fahd Jarad, Madeeha Tahir, Abdullah M. Alsharif . New computations for the two-mode version of the fractional Zakharov-Kuznetsov model in plasma fluid by means of the Shehu decomposition method. AIMS Mathematics, 2022, 7(2): 2044-2060. doi: 10.3934/math.2022117
    [6] Saleh Baqer, Theodoros P. Horikis, Dimitrios J. Frantzeskakis . Physical vs mathematical origin of the extended KdV and mKdV equations. AIMS Mathematics, 2025, 10(4): 9295-9309. doi: 10.3934/math.2025427
    [7] Azzh Saad Alshehry, Naila Amir, Naveed Iqbal, Rasool Shah, Kamsing Nonlaopon . On the solution of nonlinear fractional-order shock wave equation via analytical method. AIMS Mathematics, 2022, 7(10): 19325-19343. doi: 10.3934/math.20221061
    [8] M. S. Alqurashi, Saima Rashid, Bushra Kanwal, Fahd Jarad, S. K. Elagan . A novel formulation of the fuzzy hybrid transform for dealing nonlinear partial differential equations via fuzzy fractional derivative involving general order. AIMS Mathematics, 2022, 7(8): 14946-14974. doi: 10.3934/math.2022819
    [9] Amjad Ali, Iyad Suwan, Thabet Abdeljawad, Abdullah . Numerical simulation of time partial fractional diffusion model by Laplace transform. AIMS Mathematics, 2022, 7(2): 2878-2890. doi: 10.3934/math.2022159
    [10] Hilal Aydemir, Mehmet Merdan, Ümit Demir . A new approach to solving local fractional Riccati differential equations using the Adomian-Elzaki method. AIMS Mathematics, 2025, 10(4): 9122-9149. doi: 10.3934/math.2025420
  • The recent financial crisis and its aftermath boost the research of economic policy uncertainty and its relevant topics. In this paper, we forecast the oil return risks based on the CAViaR method and further depict the dynamic and heterogeneous features during the crisis (or non-crisis) period, as well as in different markets via DCC-GARCH models. The empirical results show the linkage of economic policy uncertainty and oil return risks, indicating an increasing trend and stronger relationship with major events. Further study shows the heterogeneous feature existing during crisis or non-crisis period, and there is heterogeneity in values and variations of their linkage in different markets. Therefore, policymakers should intervene timely in the crude oil market, release good news, and stabilize oil prices during the crisis period. During the non-crisis period, however, investors need to rationally analyze the price trend of the oil market, thereby preventing possible risks in the market.


    Due to its broad relevance and propensity to incorporate many repercussions of actual concerns, the idea of fractional calculus (FC) has garnered considerable prominence in previous decades. Classical calculus has remained a small segment of FC, despite the fact that it can demonstrate numerous critical challenges and assist us in forecasting the behaviour of intricate occurrences in impulsive integro-differential equations [1], neural networking [2], thermal energy [3], non-Newtonian fluids [4] and heat flux [5]. Despite the fact that innovators offer numerous novel concepts, several aspects should always be deduced in order to guarantee all categories of phenomenon, that will be accomplished by conquering the restrictions posed by mathematicians and scientists. This is highly pertinent when investigating of MHD electro-osmotically flow [6], epidemics [7,8,9], stability and instability of special functions [10,11,12,13], inequalities [14,15,16] as well as other disciplines. When it tends to arrive to the exploration of repercussions that assist in resolving major difficulties (such as the current global challenges), there is always room for improvements, innovation, creativeness, and extensions in analysis, and so many investigators have inferred provoking outcomes with the assistance of FC, and by incorporating efficacious methodologies with the assistance of underlying FC findings [17,18,19].

    Numerical models investigation and analysis of corresponding features are often a high priority in mathematical modeling when the relevant techniques are implemented. This is certainly pertinent in epidemic research, bifurcation, thermodynamics, electrostatistics modeling, fluid flow, plasma physics, and other fields. Several approaches, including N-solitons [20,21,22,23], solitary waves [24,25,26,27], Tan-Cot function method [28], Adomian decomposition method [29], homotopy perturbation method [30], q-homotopy analysis method [31], variation iteration method [32], collocation-shooting method [33], G/G expansion method [34], improved tan(ϕ(τ)/2)-expansion method [35], Lie symmetry analysis method [36], wavelet method [37] have been employed and refined by researchers to achieve the analytic, semi-analytic, and numerical solution of nonlinear PDEs. The Adomian decomposition method [29,38] is one of them, and it offers an efficient approach for exact-analytical solutions across a broad and comprehensive domain of specific aspects that simulate real-world issues. This strategy transforms a basic, incredibly straightforward problem into the complicated problem under investigation, and when combined with Adomian components, it offers a tremendous mathematical instrument. Numerous aspects of the Adomian decomposition method have also received considerable focus recently.

    In this analysis, we examine a nonlinear framework that explains powerful interactions between interior disturbances in the water. The Korteweg de-Vries (KdV) equations are frequently utilized to illustrate acoustic wave behaviour and its physical relevance. Due to the immense amplitude of lengthy longitudinal waves and prolonged rotating impacts, we employ a modified KdV equation. We now evaluate the following models using the isopycnic surface W(x,t), which dipicts the KdV and modified KdV equations [39], respectively:

    W(x,t)t+a1W(x,t)W(x,t)x+a2W2(x,t)W(x,t)x+b13W(x,t)x3=0, (1.1)

    where a1 and a2 signifies the quadratic and cubic non-linear coefficients, respectively. Also, the coefficient of small-scale dispersion is denoted by b1. Here, a1 and a1 presents the proportional factors associating in the aforsaid equation, and is due to the nonlinear hydrodynamic system, and it appears classically, see[40,41].

    Furthermore, we compute the exact-analytical solution of nonlinear dispersive equations K(n,n):

    W(x,t)t+x(Wn)+3x3(Wn)=0,n>1. (1.2)

    Equation (1.2) is the evolutionary model for compactons. Compactons are characterized as solitons with bounded wave lengths or solitons without exponential tails in solitary wave theory (Rosenau and Hyma, 1993). Compactons are formed by the intricate coupling of nonlinear convection x(Wn) and nonlinear dispersion 3x3(Wn) in (1.2).

    Amidst Gorge Adomian's massive boost in 1980, the Adomian decomposition method introduced a well-noted terminology. It has been intensively implemented for a diverse set of nonlinear PDEs, for instance, the Korteweg-De Vries model [42], Fisher's model [43], Zakharov–Kuznetsov equation [44] and so on. The ADM was determined to be significantly related to a variety of integral transforms, including Laplace, Swai, Mohand, Aboodh, Elzaki, and others. Humanity is continuously striving to improve performance and minimizing the method's intricacy through invention, modernity, and experimentation. In connection with this, Jafari [45] propounded a well-known integral transform which is known to generalized integral transform. The dominant feature of this transformation is that it has the ability to recapture several existing transformations, see Remark 1.

    Motivated by the above propensity, we aim to establish a semi-analytical approach by mingling the Jafari transform with the Adomian decomposition method, namely the Jafari decompostion method (JDM). With the assistance of fractional derivative operators, we constructed the approximate-analytical solutions for KdV, MKdV, K(2,2) and K(3,3). The suggested methodology helps us increase flexibility in determining the initial conditions, and its novelty is that it has a straightforward solution technique. This approach is straightforward and encompasses all of JDM accomplishments, as well as encouraging several scholars to investigate a broad spectrum of applications and processes. The tool to overcome computational complexity without any constraints, perturbations, or transformations from nonlinear to linear, or partial to ordinary differential equations, is the distinctive characteristic of the proposed approach. Furthermore, it is connected to factors that are extremely useful in bringing the findings to a favourable conclusion. It also is coupled to well-posed transformation, which tries to diminish the technique's intricacy while increasing its application and dependability.

    In this section, we evoke some essential concepts, notions, and definitions concerning fractional derivative operators depending on power and Mittag-Leffer as a kernel, along with the detailed consequences of the Jafari transform.

    Definition 2.1. ([17]) The Caputo fractional derivative (CFD) is described as follows:

    c0Dλt={1Γ(rλ)t0W(r)(x)(tx)λ+1rdx,r1<λ<r,drdtrW(t),λ=r. (2.1)

    Definition 2.2. ([18]) The Atangana-Baleanu fractional derivative operator in the Caputo form (ABC) is stated as follows:

    ABCη1Dλt(W(t))=A(λ)1λtη1W(t)Eλ[λ(tx)λ1λ]dx, (2.2)

    where WH1(a1,a2)(Sobolevspace),a1<a2,λ[0,1] and A(λ) signifies a normalization function as A(λ)=A(0)=A(1)=1.

    Definition 2.3. ([18]) The fractional integral of the ABC-operator is described as follows:

    ABCη1Iλt(W(t))=1λA(λ)W(t)+λΓ(λ)A(λ)tη1W(x)(tx)λ1dx. (2.3)

    Definition 2.4. ([45]) Consider an integrable mapping W(t) defined on a set P, then

    P={W(t):M>0,κ>0,|W(t)|<Mexp(κt),ift0}. (2.4)

    Definition 2.5. ([45]) Suppose the mappings ϕ(s),ψ(s):R+R+ such that φ(s)0sR+. The Jafari transform of the mapping W(t) presented by Q(s) is described as

    J{W(t),s}=Q(s)=ϕ(s1)0W(t)exp(ψ(s)t)dt. (2.5)

    Theorem 2.6. ([45]) (Convolution property). For Jafari transform, the subsequent holds true:

    J{W1W2}=1ϕ(s)Q1(s)Q2(s). (2.6)

    Definition 2.7. The Jafari transform of the CFD operator is stated as follows:

    J{c0Dλt(W(t)),s}=ψλ(s)Q(s1)ϕ(s)λ1κ=0ψλκ1(s1)W(κ)(0),r1<λ<r,ϕ,ψ>0. (2.7)

    Remark 1. Definition 2.7 leads to the following conclusions:

    1) Taking ϕ(s)=1 and ψ(s)=s, then we acquire the Laplace transform [46].

    2) Taking ϕ(s)1s and ψ(s)=1s, then we acquire the α-Laplace transform [47].

    3) Taking ϕ(s)=1s and ψ(s)=1s, then we acquire the Sumudu transform [48].

    4) Taking ϕ(s)=1s and ψ(s)=1, then we acquire the Aboodh transform [49].

    5) Taking ϕ(s)=s and ψ(s)=s2, then we acquire the Pourreza transform [50,51].

    6) Taking ϕ(s)=s and ψ(s)=1s, then we acquire the Elzaki transform [52].

    7) Taking ϕ(s)=u2 and ψ(s)=su2, then we acquire the Natural transform [53].

    8) Taking ϕ(s)=s2 and ψ(s)=s, then we acquire the Mohand transform [54].

    9) Taking ϕ(s)=1s2 and ψ(s)=1s, then we acquire the Swai transform [55].

    10) Taking ϕ(s)=1 and ψ(s)=1s, then we get the Kamal transform [56].

    11) Taking ϕ(s)=sα and ψ(s)=1s, then we acquire the Gtransform [57,58].

    Definition 2.8. ([59]) The Jafari transform of the ABC fractional derivative operator is described as:

    J{ABC0Dλt(W(t)),s}(λ)=A(λ)ψλ(s)λ+(1λ)ψλ(s)(Q(s)ϕ(s)ψ(s)W(0)). (2.8)

    Remark 2. Definition 2.8 leads to the following conclusions:

    1) Taking ϕ(s)=1 and ψ(s)=s, then we acquire the Laplace transform of ABC fractional derivative operator [60,61].

    2) Taking ϕ(s)=s and ψ(s)=1s, then we acquire the Elzaki transform of ABC fractional derivative operator [62].

    3) Taking ϕ(s)=ψ(s)=1s, then we get the Sumudu transform of ABC fractional derivative operator [63].

    4) Taking ϕ(s)=1 and ψ(s)=s/u2, then we get the Shehu transform of ABC fractional derivative operator [63].

    Definition 2.9. ([64]) The Mittag-Leffler function for single parameter is described as

    Eλ(z)=κ=0zκ1Γ(κλ+1),λ,z1C,(λ)0. (2.9)

    Consider the generic fractional form of PDE:

    DλtW(x,t)+LW(x,t)+NW(x,t)=F(x,t),t>0,0<λ1 (3.1)

    with ICs

    W(x,0)=G(x), (3.2)

    where Dλt=λW(x,t)tλ symbolizes the Caputo and ABC fractional derivative of order λ(0,1] while L and N denotes the linear and nonlinear factors, respectively. Also, F(x,t) represents the source term.

    Taking into account the Jafari transform to (3.1), and we acquire

    J[DλtW(x,t)+LW(x,t)+NW(x,t)]=J[F(x,t)].

    Firstly, applying the differentiation rule of Jafari transform with respect to CFD, then we apply the ABC fractional derivativ operator as follows:

    ψλ(s)U(x,s)=ϕ(s)1κ=0ψλ1κ(s)W(κ)(0)+J[LW(x,t)+NW(x,t)]+J[F(x,t)], (3.3)

    and

    ψλ(s)A(λ)λ+(1λ)ψλ(s)U(x,s)=ϕ(s)ψ(s)ψλ(s)A(λ)λ+(1λ)ψλ(s)W(0)+J[LW(x,t)+NW(x,t)]+J[F(x,t)]. (3.4)

    The inverse Jafari transform of (3.3) and (3.4) yields

    W(x,t)=J1[ϕ(s)1κ=0ψ(s)λκ1W(κ)(0)+1ψλ(s)J[F(x,t)]]J1[1ψλ(s)J[LW(x,t)+NW(x,t)]]. (3.5)

    and

    W(x,t)=J1[ϕ(s)ψ(s)W(0)+λ+(1λ)ψλ(s)ψλ(s)A(λ)J[F(x,t)]]J1[λ+(1λ)ψλ(s)ψλ(s)A(λ)J[LW(x,t)+NW(x,t)]]. (3.6)

    The generalized decomposition method solution W(x,t) is represented by the following infinite series

    W(x,t)==0W(x,t). (3.7)

    Thus, the nonlinear term N(x,t) can be evaluated by the Adomian decomposition method prescribed as

    NW(x,t)==0˜A(W0,W1,...),=0,1,..., (3.8)

    where

    ˜A(W0,W1,...)=1![ddςN(ȷ=0ςȷWȷ)]ς=0,>0.

    Inserting (3.7) and (3.8) into (3.5) and (3.6), respectively, we have

    =0W(x,t)=G(x)+˜G(x)J1[1ψλ(s)J[LW(x,t)+=0˜A]] (3.9)

    and

    =0W(x,t)=G(x)+˜G(x)J1[λ+(1λ)ψλ(s)A(λ)ψλ(s)J[LW(x,t)+=0˜A]]. (3.10)

    Consequently, the recursive technique for (3.9) and (3.10) are established as:

    W0(x,t)=G(x)+˜G(x),=0,W+1(x,t)=J1[1ψλ(s)J[L(W(x,t))+=0˜A]],1,W+1(x,t)=J1[λ+(1λ)ψλ(s)A(λ)ψλ(s)J[L(W(x,t))+=0˜A]],1. (3.11)

    In what follows, we present the various kinds of partial differential equations with the CFD and AB-frctional derivative operators, respectively.

    Example 4.1. Assume that the time-fractional KdV equation

    DλtW(x,t)6WWx(x,t)+Wxxx(x,t)=0, (4.1)

    with IC:

    W0(x,0)=2σ2exp(σx)(1+exp(σx))2. (4.2)

    Proof. Foremost, we provide the solution of (4.1) in two general cases.

    Case Ⅰ. Firstly, we apply the Caputo fractional derivative operator coupled with the Jafari transform and Adomian decomposition method. Applying the Jafari transform to (4.1).

    ψλ(s)U(x,s)ϕ(s)m1κ=0ψλκ1(s)W(κ)(0)=J[6WWx(x,t)Wxxx(x,t)]. (4.3)

    Taking into consideration the IC given in (4.2), we have

    U(x,s)=ϕ(s)ψ(s)W(x,0)+1ψλ(s)J[6WWx(x,t)Wxxx(x,t)].

    Employing the inverse Jafari transform, we obtain

    W(x,t)=J1[ϕ(s)ψ(s)W(x,0)+1ψλ(s)J[6WWx(x,t)Wxxx(x,t)]]. (4.4)

    Thanks to the JDM, we find

    W0(x,t)=J1[ϕ(s)ψ(s)W(x,0)]=2J1[ϕ(s)ψ(s)σ2exp(σx)(1+exp(σx))2]=2σ2exp(σx)(1+exp(σx))2.

    Here, we surmise that the unknown function W(x,t) can be written by an infinite series of the form

    W(x,t)==0W(x,t).

    Also, the non-linearity F(W) can be decomposed by an infinite series of polynomials represented by

    F(W)=WWx==0A,

    where W(x,t) will be evaluated recurrently, and A is the so-called polynomial of W0,W1,...,W established by [65].

    =0W+1(x,t)=J1[1ψλ(s)J[6=0(A)+=0(Wxxx)]],=0,1,2,....

    The first few Adomian polynomials are presented as follows:

    A(WWx)={W0W0x,=0,W0xW1+W1xW0,=1,W2W0x+W1W1x+W0W2x,=2, (4.5)

    For =0,1,2,3,...

    W1(x,t)=J1[1ψλ(s)J[6A0+W0xxx]]=2σ5exp(σx)(exp(σx)1)(1+exp(σx1))3tλΓ(λ+1),W2(x,t)=J1[1ψλ(s)J[6A1+W1xxx]]=2σ8exp(σx)(exp(2σx)4exp(σx)+1)(1+exp(σx1))4t2λΓ(2λ+1),.

    The approximate solution for Example 4.1 is expressed as:

    W(x,t)=W0(x,t)+W1(x,t)+W2(x,t)+W3(x,t)+...,=2σ2exp(σx)(1+exp(σx))22σ5exp(σx)(exp(σx)1)(1+exp(σx1))3tλΓ(λ+1)2σ8exp(σx)(exp(2σx)4exp(σx)+1)(1+exp(σx1))4t2λΓ(2λ+1)+.... (4.6)

    Case Ⅱ. Here, we surmise ABC fractional derivative operator coupled with the Jafari transform and Adomian decomposition method. Applying the Jafari transform for Example 4.1.

    ψλ(s)A(λ)λ+(1λ)ψλ(s)U(x,s)ϕ(s)m1κ=0ψλκ1(s)W(κ)(0)=J[6WWx(x,t)Wxxx(x,t)]. (4.7)

    Taking into consideration the IC given in (4.2), we have

    U(x,s)=ϕ(s)ψ(s)W(x,0)+λ+(1λ)ψλ(s)ψλ(s)A(λ)J[6WWx(x,t)Wxxx(x,t)].

    Employing the inverse Jafari transform, we obtain

    W(x,t)=J1[ϕ(s)ψ(s)W(x,0)+λ+(1λ)ψλ(s)ψλ(s)A(λ)J[6WWx(x,t)Wxxx(x,t)]]. (4.8)

    Thanks to the JDM, we find

    W0(x,t)=J1[ϕ(s)ψ(s)W(x,0)]=2J1[ψ(s1)ϕ(s)σ2exp(σx)(1+exp(σx))2]=2σ2exp(σx)(1+exp(σx))2.

    Here, we surmise that the unknown function W(x,t) can be written by an infinite series of the form

    W(x,t)==0W(x,t).

    Also, the non-linearity F1(W) can be decomposed by an infinite series of polynomials represented by

    F1(W)=WWx==0A,

    where W(x,t) will be evaluated recurrently, and A is the so-called polynomial of W0,W1,...,W defined in (4.5). Then, we have

    For =0,1,2,3,...

    W1(x,t)=J1[λ+(1λ)ψλ(s)ψλ(s)A(λ)J[6A0+W0xxx]]=2A(λ)σ5exp(σx)(exp(σx)1)(1+exp(σx1))3[λtλΓ(λ+1)+(1λ)],W2(x,t)=J1[λ+(1λ)ψλ(s)ψλ(s)A(λ)J[6A1+W1xxx]]=2A2(λ)σ8exp(σx)(exp(2σx)4exp(σx)+1)(1+exp(σx1))4[λ2t2λΓ(2λ+1)+2λ(1λ)tλΓ(λ+1)+(1λ)2],.

    The approximate solution for Example 4.1 is expressed as:

    W(x,t)=W0(x,t)+W1(x,t)+W2(x,t)+W3(x,t)+...,=2σ2exp(σx)(1+exp(σx))22σ5exp(σx)(exp(σx)1)A(λ)(1+exp(σx1))3[λtλΓ(λ+1)+(1λ)]2σ8exp(σx)(exp(2σx)4exp(σx)+1)A2(λ)(1+exp(σx1))4[λ2t2λΓ(2λ+1)+2λ(1λ)tλΓ(λ+1)+(1λ)2]+.... (4.9)

    For λ=1, we obtained the exact solution of Example 4.1 as

    W(x,t)=σ22sech2σ2(xσ2t).

    Figure 1 shows the evolutionary outcomes for the explicit and approximate solutions of Example 4.1 for the particular instance λ=1. The result generated by the proposed technique is remarkably similar to the exact solution, as shown in Figure 1.

    Figure 1.  Three-dimensional illustration of the exact and approximate solution of Example 4.1 when λ=1, and σ=0.05.

    Then, by considering only the first few elements of the linear equations features are integrated, we can deduce that we have accomplished a reasonable estimation with the numerical solutions of the problem. It is obvious that by adding additional components to the decomposition series (4.6) and (4.9), the cumulative error can be diminished.

    Analogously, we demonstrate the two-dimensional view of the change in fractional values of the order. We depict the response in Figure 2. It is remarkable that pairwise collisions of particle-like phenomena (including solitary waves and breathers) are fundamental mechanisms in the production of condensed soliton gas dynamics. Deep water waves, shallow groundwater waves, internally waves in a segmented sea, and fibre optics are all manifestations of these waves.

    Figure 2.  Three-dimensional illustration of the absolute error plot and 2D-approximations of Example 4.1 when λ=1,σ=0.05=0, and t=0.5.

    Remark 3. It is remarkable that equivalent version of the KdV equation is presented as

    DλtW(x,t)+6WWx(x,t)+Wxxx(x,t)=0,

    with IC:

    W0(x,0)=2σ2exp(σx)(1+exp(σx))2.

    has the solitary wave solution, when λ=1, then

    W(x,t)=σ22sech2σ2(xσ2t).

    Example 4.2. Assume that the time-fractional modified KdV equation

    DλtW(x,t)+6W2Wx(x,t)+Wxxx(x,t)=0, (4.10)

    with IC:

    W0(x,0)=2σexp(σx)1+exp(2σx). (4.11)

    Proof. Foremost, we provide the solution of (4.10) in two general cases.

    Case Ⅰ. Firstly, we apply the Caputo fractional derivative operator coupled with the Jafari transform and Adomian decomposition method.

    Applying the Jafari transform to (4.10).

    ψλ(s)U(x,s)ϕ(s)m1κ=0ψλκ1(s)W(κ)(0)=J[6W2Wx(x,t)+Wxxx(x,t)]. (4.12)

    Taking into consideration the IC given in (4.11), we have

    U(x,s)=ϕ(s)ψ(s)W(x,0)1ψλ(s)J[6W2Wx(x,t)+Wxxx(x,t)].

    Employing the inverse Jafari transform, we obtain

    W(x,t)=J1[ϕ(s)ψ(s)W(x,0)1ψλ(s)J[6W2Wx(x,t)+Wxxx(x,t)]]. (4.13)

    Thanks to the JDM, we find

    W0(x,t)=J1[ϕ(s)ψ(s)W(x,0)]=2J1[ϕ(s)ψ(s)σexp(σx)1+exp(2σx)]=2σexp(σx)1+exp(2σx).

    Here, we surmise that the unknown function W(x,t) can be written by an infinite series of the form

    W(x,t)==0W(x,t).

    Also, the non-linearity F(W) can be decomposed by an infinite series of polynomials represented by

    F(W)=W2Wx==0B,

    where W(x,t) will be evaluated recurrently, and B is the so-called polynomial of W0,W1,...,W established by [65].

    =0W+1(x,t)=J1[1ψλ(s)J[6=0(B)+=0(Wxxx)]],=0,1,2,....

    The first few Adomian polynomials are presented as follows:

    B(W2Wx)={W20W0x,=0,W0x(2W0W1)+W1xW20,=1,(2W2W0+W21)W0x+(2W0W1)W1x+W20W2x,=2, (4.14)

    For =0,1,2,3,...

    W1(x,t)=J1[1ψλ(s)J[6B0+W0xxx]]=2σ4exp(σx)(1exp(2σx))(1+exp(2σx1))2tλΓ(λ+1),W2(x,t)=J1[1ψλ(s)J[6B1+W1xxx]]=2σ7exp(σx)(16exp(2σx)+exp(4σx))(1+exp(2σx1))3t2λΓ(2λ+1),.

    The approximate solution for Example 4.2 is expressed as:

    W(x,t)=W0(x,t)+W1(x,t)+W2(x,t)+W3(x,t)+...,=2σexp(σx)1+exp(2σx)2σ4exp(σx)(1exp(2σx))(1+exp(2σx1)2tλΓ(λ+1)+2σ7exp(σx)(16exp(2σx)+exp(4σx))(1+exp(2σx1)3t2λΓ(2λ+1)+.... (4.15)

    Case Ⅱ. Here, we surmise ABC fractional derivative operator coupled with the Jafari transform and Adomian decomposition method.

    Applying the Jafari transform on (4.10).

    ψλ(s)A(λ)λ+(1λ)ψλ(s)U(x,s)ϕ(s)m1κ=0ψλκ1(s)W(κ)(0)=J[6W2Wx(x,t)+Wxxx(x,t)]. (4.16)

    Taking into consideration the IC given in (4.11), we have

    U(x,s)=ϕ(s)ψ(s)W(x,0)λ+(1λ)ψλ(s)ψλ(s)A(λ)J[6W2Wx(x,t)+Wxxx(x,t)].

    Employing the inverse Jafari transform, we obtain

    W(x,t)=J1[ϕ(s)ψ(s)W(x,0)λ+(1λ)ψλ(s)ψλ(s)A(λ)J[6W2Wx(x,t)+Wxxx(x,t)]]. (4.17)

    Thanks to the JDM, we find

    W0(x,t)=J1[ϕ(s)ψ(s)W(x,0)]=2J1[ψ(s1)ϕ(s)σexp(σx)1+exp(2σx)]=σexp(σx)1+exp(2σx).

    Here, we surmise that the unknown function W(x,t) can be written by an infinite series of the form

    W(x,t)==0W(x,t).

    Also, the non-linearity F(W), can be decomposed by an infinite series of polynomials represented by

    F1(W)=W2Wx==0B,

    where W(x,t) will be evaluated recurrently, and B is the so-called polynomial of W0,W1,...,W defined in (4.14).

    For =0,1,2,3,...

    W1(x,t)=J1[λ+(1λ)ψλ(s)ψλ(s)A(λ)J[6B0+W0xxx]]=2A(λ)σ4exp(σx)(1exp(2σx))(1+exp(2σx1)2[λtλΓ(λ+1)+(1λ)],W2(x,t)=J1[λ+(1λ)ψλ(s)ψλ(s)A(λ)J[6A1+W1xxx]]=2A2(λ)σ7exp(σx)(16exp(2σx)+exp(4σx))(1+exp(2σx1))3×[λ2t2λΓ(2λ+1)+2λ(1λ)tλΓ(λ+1)+(1λ)2],.

    The approximate solution for Example 4.2 is expressed as:

    W(x,t)=W0(x,t)+W1(x,t)+W2(x,t)+W3(x,t)+...,=σexp(σx)1+exp(2σx)2σ4exp(σx)(1exp(2σx))A(λ)(1+exp(2σx1))2[λtλΓ(λ+1)+(1λ)]+2σ7exp(σx)(16exp(2σx)+exp(4σx))A2(λ)(1+exp(2σx1))3×[λ2t2λΓ(2λ+1)+2λ(1λ)tλΓ(λ+1)+(1λ)2]+.... (4.18)

    For λ=1, we obtained the exact solution of Example 4.2 as

    W(x,t)=±σsechσ(xσ2t).

    Figure 3 shows the evolutionary outcomes for the explicit and approximate solutions of Example 4.2 for the particular instance λ=1. The result generated by the proposed technique is remarkably similar to the exact solution, as shown in Figure 3.

    Figure 3.  Three-dimensional illustration of the exact and approximate solution of Example 4.2 when λ=1, and σ=0.5.

    Then, by considering only the first few elements of the nonlinear equations features are integrated, we can deduce that we have accomplished a reasonable estimation with the numerical solutions of the problem. It is obvious that by adding additional components to the decomposition series (4.15) and (4.18), the cumulative error can be diminished.

    Analogously, we demonstrate the two-dimensional view of the change in fractional values of the order. Figure 4 depicts the response for exact CFD and AB fractional derivative operators. It is remarkable that pairwise collisions of particle-like phenomena (including solitary waves and breathers) are fundamental mechanisms in the production of condensed soliton gas dynamics. Deep water waves, shallow groundwater waves, internally waves in a segmented sea, and fibre optics are all manifestations of these waves.

    Figure 4.  Two-dimensional illustration for change in fractional values of the order of Example 4.2 when σ=0.05 and t=0.5.

    Example 4.3. Assume that the time-fractional K(2,2) equation

    DλtW(x,t)+(W2)x(x,t)+(W2)xxx(x,t)=0, (4.19)

    with IC:

    W0(x,0)=43σcos2(x4). (4.20)

    Proof. Foremost, we provide the solution of (4.19) in two general cases.

    Case Ⅰ. Firstly, we apply the Caputo fractional derivative operator coupled with the Jafari transform and Adomian decomposition method.

    Applying the Jafari transform on (4.19).

    ψλ(s)U(x,s)ϕ(s)m1κ=0ψλκ1(s)W(κ)(0)=J[(W2)x(x,t)+(W2)xxx(x,t)]. (4.21)

    Taking into consideration the IC given in (4.20), we have

    U(x,s)=ϕ(s)ψ(s)W(x,0)1ψλ(s)J[(W2)x(x,t)+(W2)xxx(x,t)].

    Employing the inverse Jafari transform, we obtain

    W(x,t)=J1[ϕ(s)ψ(s)W(x,0)1ψλ(s)J[(W2)x(x,t)+(W2)xxx(x,t)]]. (4.22)

    Thanks to the JDM, we find

    W0(x,t)=J1[ϕ(s)ψ(s)43σcos2(x4)]=2J1[ϕ(s)ψ(s)43σcos2(x4)]=43σcos2(x4).

    Here, we surmise that the unknown function W(x,t) can be written by an infinite series of the form

    W(x,t)==0W(x,t).

    Also, the non-linearities F1(W) and F2(W) can be decomposed by an infinite series of polynomials represented by

    F1(W)=(W2)x==0D,F2(W)=(W2)xxx==0E,

    where W(x,t) will be evaluated recurrently, and D and E are the so-called polynomial of W0,W1,...,W established by [65].

    =0W+1(x,t)=J1[1ψλ(s)J[=0(D)+=0(E)]],=0,1,2,....

    The first few Adomian polynomials are presented as follows:

    D((W2)x)={W20x,=0,(2W0W1)x,=1,(2W2W0+W21)x,=2,E((W2)xxx)={W20xxx,=0,(2W0W1)xxx,=1,(2W2W0+W21)xxx,=2, (4.23)

    For =0,1,2,3,...

    W1(x,t)=J1[1ψλ(s)J[D0+E0]]=σ23sin(x2)tλΓ(λ+1),W2(x,t)=J1[1ψλ(s)J[D1+E1]]=σ36sin(x2)t2λΓ(2λ+1),W3(x,t)=J1[1ψλ(s)J[D2+E2]]=σ412sin(x2)t3λΓ(3λ+1).

    The approximate solution for Example 4.3 is expressed as:

    W(x,t)=W0(x,t)+W1(x,t)+W2(x,t)+W3(x,t)+...,=43σcos2(x4)+σ23sin(x2)tλΓ(λ+1)σ36sin(x2)t2λΓ(2λ+1)σ412sin(x2)t3λΓ(3λ+1)+.... (4.24)

    Case Ⅱ. Here, we surmise ABC fractional derivative operator coupled with the Jafari transform and Adomian decomposition method. Applying the Jafari transform for Example 4.19.

    ψλ(s)A(λ)λ+(1λ)ψλ(s)U(x,s)ϕ(s)m1κ=0ψλκ1(s)W(κ)(0)=J[(W2)x(x,t)+(W2)xxx(x,t)]. (4.25)

    Taking into consideration the IC given in (4.20), we have

    U(x,s)=ϕ(s)ψ(s)W(x,0)λ+(1λ)ψλ(s)ψλ(s)A(λ)J[(W2)x(x,t)+(W2)xxx(x,t)].

    Employing the inverse Jafari transform, we obtain

    W(x,t)=J1[ϕ(s)ψ(s)W(x,0)λ+(1λ)ψλ(s)ψλ(s)A(λ)J[(W2)x(x,t)+(W2)xxx(x,t)]]. (4.26)

    Thanks to the JDM, we find

    W0(x,t)=J1[ϕ(s)ψ(s)W(x,0)]=2J1[ψ(s1)ϕ(s)43σcos2(x4)]=43σcos2(x4).

    Here, we surmise that the unknown function W(x,t) can be written by an infinite series of the form

    W(x,t)==0W(x,t).

    Also, the non-linearity Fȷ(W),ȷ=1,2 can be decomposed by an infinite series of polynomials represented by

    F1(W)=(W2)x==0D,F2(W)=(W2)xxx==0E,

    where W(x,t) will be evaluated recurrently, and D and E are the so-called polynomial of W0,W1,...,W established defined in (4.23). Then, we have

    For =0,1,2,3,...

    W1(x,t)=J1[λ+(1λ)ψλ(s)ψλ(s)A(λ)J[D0+E0]]=σ23A(λ)sin(x2)[λtλΓ(λ+1)+(1λ)],W2(x,t)=J1[λ+(1λ)ψλ(s)ψλ(s)A(λ)J[D1+E1]]=σ36A2(λ)sin(x2)[λ2t2λΓ(2λ+1)+2λ(1λ)tλΓ(λ+1)+(1λ)2],.

    The approximate solution for Example 4.3 is expressed as:

    W(x,t)=W0(x,t)+W1(x,t)+W2(x,t)+W3(x,t)+...,=43σcos2(x4)+σ23A(λ)sin(x2)[λtλΓ(λ+1)+(1λ)]σ36A2(λ)sin(x2)[λ2t2λΓ(2λ+1)+2λ(1λ)tλΓ(λ+1)+(1λ)2]+.... (4.27)

    For λ=1, we obtained the closed form solution of Example 4.3 as

    W(x,t)={43σcos2(xσt4),|xσt|2π,0,otherwise..

    Figure 5 shows the evolutionary outcomes for the explicit and approximate solutions of Example 4.3 for the particular instance λ=1. The result generated by the proposed technique is remarkably similar to the exact solution, as shown in Figure 5.

    Figure 5.  Three-dimensional illustration of the exact and approximate solution of Example 4.3 when λ=1 and σ=0.05.

    Then, by considering only the first few elements of the nonlinear equations features are integrated, we can deduce that we have accomplished a reasonable estimation with the numerical solutions of the problem. It is obvious that by adding additional components to the decomposition series (4.24) and (4.27), the cumulative error can be diminished.

    Analogously, we demonstrate the two-dimensional view of the change in fractional values of the order. Figure 6 depicts the response for exact CFD and AB fractional derivative operators.

    Figure 6.  Two-dimensional illustration of the exact and approximate solution for the change in fractional values of the order of Example 4.3 when λ=1,σ=0.05 and t=0.5.

    For a variation of the K(2,2) equation, constrained traveling-wave solutions are achieved. We acquire hump-shaped and valley-shaped solitary-wave solutions, as well as some periodic solutions, for the focusing branch. It is worth noting that optimal focusing provides the aggregate of the frequency and amplitude of the originating waves in the engaging phase, as illustrated in reference [66].

    Example 4.4. Assume that the time-fractional K(3,3) equation

    DλtW(x,t)+(W3)x(x,t)+(W3)xxx(x,t)=0, (4.28)

    with IC:

    W0(x,0)=3σ2cos(x3). (4.29)

    Proof. Foremost, we provide the solution of (4.28) in two general cases.

    Case Ⅰ. Firstly, we apply the Caputo fractional derivative operator coupled with the Jafari transform and Adomian decomposition method.

    Applying the Jafari transform on (4.28).

    ψλ(s)U(x,s)ϕ(s)m1κ=0ψλκ1(s)W(κ)(0)=J[(W3)x(x,t)+(W3)xxx(x,t)]. (4.30)

    Taking into consideration the IC given in (4.29), we have

    U(x,s)=ϕ(s)ψ(s)W(x,0)1ψλ(s)J[(W3)x(x,t)+(W3)xxx(x,t)].

    Employing the inverse Jafari transform, we obtain

    W(x,t)=J1[ϕ(s)ψ(s)W(x,0)1ψλ(s)J[(W3)x(x,t)+(W3)xxx(x,t)]]. (4.31)

    Thanks to the JDM, we find

    W0(x,t)=J1[ϕ(s)ψ(s)3σ2cos(x3)]=2J1[ϕ(s)ψ(s)3σ2cos(x3)]=3σ2cos(x3).

    Here, we surmise that the unknown function W(x,t) can be written by an infinite series of the form

    W(x,t)==0W(x,t).

    Also, the non-linearities F1(W) and F2(W) can be decomposed by an infinite series of polynomials represented by

    F1(W)=(W3)x==0G,F2(W)=(W3)xxx==0H,

    where W(x,t) will be evaluated recurrently, and G and H are the so-called polynomial of W0,W1,...,W established by [65].

    =0W+1(x,t)=J1[1ψλ(s)J[=0(G)+=0(H)]],=0,1,2,....

    The first few Adomian polynomials are presented as follows:

    G((W3)x)={W30x,=0,(3W20W1)x,=1,(3W2W20+3W21W0)x,=2,E((W3)xxx)={W20xxx,=0,(3W20W1)xxx,=1,(3W2W20+3W21W0)xxx,=2, (4.32)

    For =0,1,2,3,...

    W1(x,t)=J1[1ψλ(s)J[G0+H0]]=6σ36sin(x3)tλΓ(λ+1),W2(x,t)=J1[1ψλ(s)J[G1+H1]]=6σ518sin(x3)t2λΓ(2λ+1),W3(x,t)=J1[1ψλ(s)J[G2+H2]]=6σ754sin(x3)t3λΓ(3λ+1).

    The approximate solution for Example 4.4 is expressed as:

    W(x,t)=W0(x,t)+W1(x,t)+W2(x,t)+W3(x,t)+...,=3σ2cos(x3)+6σ36sin(x3)tλΓ(λ+1)6σ518sin(x3)t2λΓ(2λ+1)6σ754sin(x3)t3λΓ(3λ+1)+.... (4.33)

    Case Ⅱ. Here, we surmise ABC fractional derivative operator coupled with the Jafari transform and Adomian decomposition method. Applying the Jafari transform for Example 4.28.

    ψλ(s)A(λ)λ+(1λ)ψλ(s)U(x,s)ϕ(s)m1κ=0ψλκ1(s)W(κ)(0)=J[(W3)x(x,t)+(W3)xxx(x,t)]. (4.34)

    Taking into consideration the IC given in (4.29), we have

    U(x,s)=ϕ(s)ψ(s)W(x,0)λ+(1λ)ψλ(s)ψλ(s)A(λ)J[(W3)x(x,t)+(W3)xxx(x,t)].

    Employing the inverse Jafari transform, we obtain

    W(x,t)=J1[ϕ(s)ψ(s)W(x,0)λ+(1λ)ψλ(s)ψλ(s)A(λ)J[(W3)x(x,t)+(W3)xxx(x,t)]]. (4.35)

    Thanks to the JDM, we find

    W0(x,t)=J1[ϕ(s)ψ(s)W(x,0)]=2J1[ψ(s1)ϕ(s)3σ2cos(x3)]=3σ2cos(x3).

    Here, we surmise that the unknown function W(x,t) can be written by an infinite series of the form

    W(x,t)==0W(x,t).

    Also, the non-linearity Fȷ(W),ȷ=1,2 can be decomposed by an infinite series of polynomials represented by

    F1(W)=(W3)x==0G,F2(W)=(W3)xxx==0H,

    where W(x,t) will be evaluated recurrently, and D and E are the so-called polynomial of W0,W1,...,W established defined in (4.32). Then, we have

    For =0,1,2,3,...

    W1(x,t)=J1[λ+(1λ)ψλ(s)ψλ(s)A(λ)J[G0+H0]]=6σ36A(λ)sin(x3)[λtλΓ(λ+1)+(1λ)],W2(x,t)=J1[λ+(1λ)ψλ(s)ψλ(s)A(λ)J[G1+H1]]=6σ518A2(λ)sin(x3)[λ2t2λΓ(2λ+1)+2λ(1λ)tλΓ(λ+1)+(1λ)2],.

    The approximate solution for Example 4.4 is expressed as:

    W(x,t)=W0(x,t)+W1(x,t)+W2(x,t)+W3(x,t)+...,=3σ2cos(x3)+6σ36A(λ)sin(x3)[λtλΓ(λ+1)+(1λ)]6σ518A2(λ)sin(x3)[λ2t2λΓ(2λ+1)+2λ(1λ)tλΓ(λ+1)+(1λ)2]+.... (4.36)

    For λ=1, we obtained the closed form solution of Example 4.4 as

    W(x,t)={6σ2σcos(xσt3),|xσt|3π2,0,otherwise..

    Figure 7 shows the evolutionary outcomes for the explicit and approximate solutions of Example 4.4 for the particular instance λ=1. The result generated by the proposed technique is remarkably similar to the exact solution, as shown in Figure 7.

    Figure 7.  Three-dimensional illustration of the exact and approximate solution of Example 4.4 when λ=1 and σ=0.05.

    Then, by considering only the first few elements of the nonlinear equations features are integrated, we can deduce that we have accomplished a reasonable estimation with the numerical solutions of the problem. It is obvious that by adding additional components to the decomposition series (4.33) and (4.36), the cumulative error can be diminished.

    Analogously, we demonstrate the two-dimensional view of the change in fractional values of the order. Figure 8 depicts the response for exact CFD and AB fractional derivative operators.

    Figure 8.  Two-dimensional illustration of the exact and approximate solution of change in fractional values of the order of Example 4.4 when λ=1,σ=0.5 and t=0.5.

    For a variation of the K(3,3) equation, constrained traveling-wave solutions are achieved. We acquire hump-shaped and valley-shaped solitary-wave solutions, as well as some periodic solutions, for the focusing branch. It is worth noting that optimal focusing provides the aggregate of the frequency and amplitude of the originating waves in the engaging phase, as illustrated in reference [66].

    In this paper, we conducted a novel algorithm based on the Jafari transform and Adomin decomposition method, known as the Jafari decomposition method. In the time-fractional technique, we investigated several models such as KdV, mKdV, K (2,2), and K (3,3). To comprehend their physical interpretation, we researched and examined several novel families of solutions and their simulation studies, presented in two-dimensional and three-dimensional plots. The new discoveries concerned the hyperbolic function, trigonometric function, exponential function, and constant function. These new solutions and results might be appreciated in the laser, plasma sciences and wave pattern. To summarise, the suggested method stated above was determined to solve this collection of challenges by utilizing successive fast converging approximations without any limiting requirements or manipulations that changed the physical attributes of the concerns. Also, increasing the recursive procedure leads to the closed form solution of the governing equation.

    The authors declare that they have no competing interests.



    [1] Aastveit KA, Bjørnland HC, Thorsrud LA (2015) What drives oil prices? Emerging versus developed economies. J Appl Econ 30: 1013–1028.
    [2] Aastveit KA, Natvik GJ, Sola S (2017) Economic uncertainty and the influence of monetary policy. J Int Money Finance 76: 50–67.
    [3] Alexopoulos M, Cohen J (2015) The power of print: Uncertainty shocks, markets, and the economy. Int Rev Econ Finance 40: 8–28.
    [4] Aloui R, Gupta R, Miller SM (2016) Uncertainty and crude oil returns. Energy Econ 55: 92–100.
    [5] Antonakakis N, Chatziantoniou I, Filis G (2014) Dynamic spillovers of oil price shocks and economic policy uncertainty. Energy Econ, 44: 433–447.
    [6] Aye G, Gupta R, Hammoudeh S, et al. (2015) Forecasting the price of gold using dynamic model averaging. Int Rev Financ Anal 41: 257–266.
    [7] Baker SR, Bloom N, Davis SJ (2016) Measuring economic policy uncertainty. Q J Econ 131: 1593–1636.
    [8] Balcilar M, Bekiros S, Gupta R (2017) The role of news-based uncertainty indices in predicting oil markets: A hybrid nonparametric quantile causality method. Empirical Econ 53: 879–889.
    [9] Balcilar M, Gupta R, Kyei C, et al. (2016) Does economic policy uncertainty predict exchange rate returns and volatility? Evidence from a nonparametric causality-in-quantiles test. Open Econ Rev 27: 229–250.
    [10] Baumeister C, Kilian L (2015) Forecasting the real price of oil in a changing world: A forecast combination approach. J Bus Econ Stat 33: 338–351.
    [11] Baumeister C, Kilian L (2016) Forty years of oil price fluctuations: Why the price of oil may still surprise us. J Econ Perspect 30: 139–60.
    [12] Baumeister C, Peersman G (2013) The role of time‐varying price elasticities in accounting for volatility changes in the crude oil market. J Appl Econ 28: 1087–1109.
    [13] Berger T, Uddin GS (2016) On the dynamic dependence between equity markets, commodity futures and economic uncertainty indexes. Energy Econ 56: 374–383.
    [14] Bekiros S, Gupta R, Paccagnini A (2015) Oil price forecastability and economic uncertainty. Econ Lett 132: 125–128.
    [15] Bernal O, Gnabo JY, Guilmin G (2016) Economic policy uncertainty and risk spillovers in the Eurozone. J Int Money Finance 65: 24–45.
    [16] Bernardi M, Catania L (2016) Comparison of Value-at-Risk models using the MCS approach. Comput Stat 31: 579–608.
    [17] Bollerslev T, Engle RF, Wooldridge JM (1988) A capital asset pricing model with time-varying covariances. J Political Econ 96: 116–131.
    [18] Bordo MD, Duca JV, Koch C (2016a) Economic policy uncertainty and the credit channel: Aggregate and bank level US evidence over several decades. J Financ Stab 26: 90–106.
    [19] Bordo MD, Meissner CM (2016b) Fiscal and financial crises. NBER Working Paper, No. 22059.
    [20] Brogaard J, Detzel A (2015) The asset-pricing implications of government economic policy uncertainty. Manage Sci 61: 3–18.
    [21] Caggiano G, Castelnuovo E, Figueres JM (2017) Economic policy uncertainty and unemployment in the United States: A nonlinear approach. Econ Lett 151: 31–34.
    [22] Caporale GM, AliF M, Spagnolo N (2015) Oil price uncertainty and sectoral stock returns in China: A time-varying approach. China Econ Rev 34: 311–321.
    [23] Çolak G, Durnev A, Qian Y (2017) Political uncertainty and IPO activity: Evidence from US gubernatorial elections. J Financ Quant Anal 52: 2523–2564.
    [24] Cunado J, Jo S, de Gracia FP (2015) Macroeconomic impacts of oil price shocks in Asian economies. Energy Policy 86: 867–879.
    [25] Dai Y, Xie W, Jiang Z, et al. (2016) Correlation structure and principal components in the global crude oil market. Empirical Econ 51: 1501–1519.
    [26] Engle R (2002) Dynamic conditional correlation: A simple class of multivariate generalized autoregressive conditional heteroskedasticity models. J Bus Econ Stat 20: 339–350.
    [27] Engle RF, Manganelli S (2004) CAViaR: Conditional Autoregressive Value at Risk by Regression Quantiles. J Bus Econ Stat 22: 367–381.
    [28] Ferraty F, Quintela-Del-Río A (2016) Conditional VAR and Expected Shortfall: A New Functional Approach. Econ Rev 35: 263–292.
    [29] Ftiti Z, Guesmi K, Teulon F (2014) Oil shocks and Economic Growth in OPEC countries No. 2014–064.
    [30] Gao R, Zhang B (2016) How does economic policy uncertainty drive gold–stock correlations? Evidence from the UK. Appl Econ 48: 3081–3087.
    [31] Gkillas K, Katsiampa P (2018) An application of extreme value theory to cryptocurrencies. Econ Lett 164: 109–111.
    [32] Gong X, Wen F, Xia X, et al. (2017) Investigating the risk-return trade-off for crude oil futures using high-frequency data. Appl energy 196: 152–161.
    [33] Handley K, Limão N (2017) Policy uncertainty, trade, and welfare: Theory and evidence for China and the United States. Am Econ Rev 107: 2731–2783.
    [34] Jia X, An H, Fang W, et al. (2015) How do correlations of crude oil prices co-move? A grey correlation-based wavelet perspective. Energy Econ 49: 588–598.
    [35] Juvenal L, Petrella I (2015) Speculation in the oil market. J Appl Econ 30: 621–649.
    [36] Kang W, de Gracia FP, Ratti RA (2017) Oil price shocks, policy uncertainty, and stock returns of oil and gas corporations. J Int Money Finance 70: 344–359.
    [37] Kang W, Ratti RA (2015) Oil shocks, policy uncertainty and stock returns in China. Econ Transition 23: 657–676.
    [38] Kellogg R (2014) The effect of uncertainty on investment: Evidence from Texas oil drilling. Am Econ Rev 104: 1698–1734.
    [39] Laporta AG, L Merlo, Petrella L (2018) Selection of Value at Risk Models for Energy Commodities. Energy Econ 74: 628–643.
    [40] Li Z, Wang C, Nie P, et al. (2018) Green loan and subsidy for promoting clean production innovation. J Cleaner Prod 187: 421–431.
    [41] Li, X, Peng L (2017) US economic policy uncertainty and linkages between Chinese and US stock markets. Econ Modell 61: 27–39.
    [42] Li X, Ma J, Wang S, et al. (2015) How does Google search affect trader positions and crude oil prices? Econ Modell 49: 162–171.
    [43] Li Z, Dong H, Huang Z, et al. (2018) Asymmetric Effects on Risks of Virtual Financial Assets (VFAs) in different regimes: A Case of Bitcoin. Quant Finance Econ 2: 860–883.
    [44] Liu Z, Ye Y, Ma F, et al. (2017) Can economic policy uncertainty help to forecast the volatility: A multifractal perspective. Phys A: Stat Mech its Appl 482: 181–188.
    [45] Mensi W, Hammoudeh S, Shahzad SJH, et al. (2017) Modeling systemic risk and dependence structure between oil and stock markets using a variational mode decomposition-based copula method. J Banking Finance 75: 258–279.
    [46] Narayan PK, Gupta R (2015) Has oil price predicted stock returns for over a century? Energy Economics 48: 18–23.
    [47] Naser H (2016) Estimating and forecasting the real prices of crude oil: A data rich model using a dynamic model averaging (DMA) approach. Energy Econ 56: 75–87.
    [48] Phan DHB, Sharma SS, Narayan PK (2015) Oil price and stock returns of consumers and producers of crude oil. J Int Finan Markets, Inst Money 34: 245–262.
    [49] Qureshi K (2016) Value-at-Risk: The Effect of Autoregression in a Quantile Process. arXiv preprint arXiv: 1605.04940.
    [50] Reboredo JC, Uddin GS (2016) Do financial stress and policy uncertainty have an impact on the energy and metals markets? A quantile regression approach. Int Rev Econ Finance 43: 284–298.
    [51] Sim N, Zhou H (2015) Oil prices, US stock return, and the dependence between their quantiles. J Banking Finance 55: 1–8.
    [52] Singleton KJ (2013) Investor flows and the 2008 boom/bust in oil prices. Manage Sci 60: 300–318.
    [53] Tsai IC (2017) The source of global stock market risk: A viewpoint of economic policy uncertainty. Econ Modell 60: 122–131.
    [54] Waisman M, Ye P, Zhu Y (2015) The effect of political uncertainty on the cost of corporate debt. J Finan Stab 16: 106–117.
    [55] Wang J, Wang J (2016) Forecasting energy market indices with recurrent neural networks: Case study of crude oil price fluctuations. Energy 102: 365–374.
    [56] Wen F, Xiao J, Huang C, et al. (2018) Interaction between oil and US dollar exchange rate: Nonlinear causality, time-varying influence and structural breaks in volatility. Appl Econ 50: 319–334.
    [57] Wisniewski TP, Lambe BJ (2015) Does economic policy uncertainty drive CDS spreads? Int Rev Finan Anal 42: 447–458.
    [58] Yin L (2016) Does oil price respond to macroeconomic uncertainty? New evidence. Empirical Econ 51: 921–938.
    [59] You W, Guo Y, Zhu H, et al. (2017) Oil price shocks, economic policy uncertainty and industry stock returns in China: Asymmetric effects with quantile regression. Energy Econ 68: 1–18.
    [60] Zhang J, Zhang Y, Zhang L (2015) A novel hybrid method for crude oil price forecasting. Energy Econ 49: 649–659.
    [61] Zhang YJ, Zhang L (2015) Interpreting the crude oil price movements: Evidence from the Markov regime switching model. Appl Energy 143: 96–109.
  • This article has been cited by:

    1. Saima Rashid, Muhammad Kashif Iqbal, Ahmed M. Alshehri, Rehana Ashraf, Fahd Jarad, A comprehensive analysis of the stochastic fractal–fractional tuberculosis model via Mittag-Leffler kernel and white noise, 2022, 39, 22113797, 105764, 10.1016/j.rinp.2022.105764
    2. Pooyan Alinaghi Hosseinabadi, Ali Soltani Sharif Abadi, Hemanshu Pota, Sundarapandian Vaidyanathan, Saad Mekhilef, Kamal Shah, Adaptive Finite-Time Sliding Mode Backstepping Controller for Double-Integrator Systems with Mismatched Uncertainties and External Disturbances, 2022, 2022, 1607-887X, 1, 10.1155/2022/3758220
    3. Saima Rashid, Fahd Jarad, Stochastic dynamics of the fractal-fractional Ebola epidemic model combining a fear and environmental spreading mechanism, 2023, 8, 2473-6988, 3634, 10.3934/math.2023183
    4. Timilehin Kingsley Akinfe, Adedapo Chris Loyinmi, An improved differential transform scheme implementation on the generalized Allen–Cahn​ equation governing oil pollution dynamics in oceanography, 2022, 6, 26668181, 100416, 10.1016/j.padiff.2022.100416
    5. Maysaa Al-Qurashi, Sobia Sultana, Shazia Karim, Saima Rashid, Fahd Jarad, Mohammed Shaaf Alharthi, Identification of numerical solutions of a fractal-fractional divorce epidemic model of nonlinear systems via anti-divorce counseling, 2022, 8, 2473-6988, 5233, 10.3934/math.2023263
    6. Jarunee Soontharanon, Muhammad Aamir Ali, Hüseyin Budak, Pinar Kösem, Kamsing Nonlaopon, Thanin Sitthiwirattham, Behrouz Parsa Moghaddam, Some New Generalized Fractional Newton’s Type Inequalities for Convex Functions, 2022, 2022, 2314-8888, 1, 10.1155/2022/6261970
    7. Saima Rashid, Saad Ihsan Butt, Zakia Hammouch, Ebenezer Bonyah, Alexander Meskhi, An Efficient Method for Solving Fractional Black-Scholes Model with Index and Exponential Decay Kernels, 2022, 2022, 2314-8888, 1, 10.1155/2022/2613133
    8. Saima Rashid, Fahd Jarad, Hajid Alsubaie, Ayman A. Aly, Ahmed Alotaibi, A novel numerical dynamics of fractional derivatives involving singular and nonsingular kernels: designing a stochastic cholera epidemic model, 2023, 8, 2473-6988, 3484, 10.3934/math.2023178
    9. Khadija Aayadi, Khalid Akhlil, Sultana Ben Aadi, Hicham Mahdioui, Weak solutions to the time-fractional g-Bénard equations, 2022, 2022, 1687-2770, 10.1186/s13661-022-01649-3
    10. Saima Rashid, Bushra Kanwal, Muhammad Attique, Ebenezer Bonyah, Ibrahim Mahariq, An Efficient Technique for Time-Fractional Water Dynamics Arising in Physical Systems Pertaining to Generalized Fractional Derivative Operators, 2022, 2022, 1563-5147, 1, 10.1155/2022/7852507
    11. Haresh P. Jani, Twinkle R. Singh, Study of concentration arising in longitudinal dispersion phenomenon by Aboodh transform homotopy perturbation method, 2022, 8, 2349-5103, 10.1007/s40819-022-01363-9
    12. Maysaa Al Qurashi, Saima Rashid, Fahd Jarad, A computational study of a stochastic fractal-fractional hepatitis B virus infection incorporating delayed immune reactions via the exponential decay, 2022, 19, 1551-0018, 12950, 10.3934/mbe.2022605
    13. Kingsley Timilehin Akinfe, A reliable analytic technique for the modified prototypical Kelvin–Voigt viscoelastic fluid model by means of the hyperbolic tangent function, 2023, 7, 26668181, 100523, 10.1016/j.padiff.2023.100523
    14. Rachid Belgacem, Ahmed Bokhari, Dumitru Baleanu, Salih Djilali, New generalized integral transform via Dzherbashian--Nersesian fractional operator, 2024, 14, 2146-5703, 90, 10.11121/ijocta.1449
    15. Emmanuel Kengne, Conformable derivative in a nonlinear dispersive electrical transmission network, 2024, 112, 0924-090X, 2139, 10.1007/s11071-023-09121-2
    16. Nan Jiang, Research on stability and control strategies of fractional-order differential equations in nonlinear dynamic systems, 2025, 1472-7978, 10.1177/14727978251346078
  • Reader Comments
  • © 2019 the Author(s), licensee AIMS Press. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0)
通讯作者: 陈斌, bchen63@163.com
  • 1. 

    沈阳化工大学材料科学与工程学院 沈阳 110142

  1. 本站搜索
  2. 百度学术搜索
  3. 万方数据库搜索
  4. CNKI搜索

Metrics

Article views(6378) PDF downloads(667) Cited by(34)

Other Articles By Authors

/

DownLoad:  Full-Size Img  PowerPoint
Return
Return

Catalog