Modified Korteweg-de Vries Equation Research Articles

Conservation laws, periodic and rational solutions for an extended modified Korteweg–de Vries equation

We study an integrable extended modified Korteweg–de Vries equation, which contains the fifth-order dispersion and relevant higher-order nonlinear terms. The infinitely many conservation laws are constructed based on the Lax pair. A general Nth-order periodic solution is obtained by means of the N-fold Darboux transformation (DT), and a simple representation of the Nth-order rational solution is derived from the generalized DT by using the limit approach. As an application, the explicit periodic and rational solutions from first to second order are given, and some typical nonlinear wave patterns such as the doubly periodic lattice-like and doubly localized high-peak waves are shown. It is interestingly found that, the doubly localized high-peak wave can be converted into a W-shaped soliton in the second-order rational solution due to the existence of higher-order terms.

Painlevé Test, Bäcklund Transformation and Consistent Riccati Expansion Solvability for two Generalised Cylindrical Korteweg-de Vries Equations with Variable Coefficients

Abstract In this paper, the integrability of the (2+1)-dimensional cylindrical modified Korteweg-de Vries equation and the (3+1)-dimensional cylindrical Korteweg-de Vries equation with variable coefficients arising in dusty plasmas in its generalised form was studied by two different techniques: the Painlevé test and the consistent Riccati expansion solvability. The integrability conditions and Bäcklund transformations are constructed. By using Bäcklund transformations and the solutions of the Riccati equation many new exact solutions are found for the two equations in this study. Finally, the application of the obtained solutions in dusty plasmas is investigated.

Global well-posedness for the fifth-order mKdV equation

We prove the global well-posedness for the Cauchy problem of fifth-order modified Korteweg–de Vries equation in Sobolev spaces H s (ℝ) for s > $$ - \frac{3}{{22}}$$ . The main approach is the “I-method” together with the multilinear multiplier analysis.

Nonlinear waves of a nonlocal modified KdV equation in the atmospheric and oceanic dynamical system

A new general nonlocal modified KdV equation is derived from the nonlinear inviscid dissipative and equivalent barotropic vorticity equation in a β-plane. The nonlocal property is manifested in the shifted parity and delayed time reversal symmetries. Exact solutions of the nonlocal modified KdV equation are obtained including periodic waves, kink waves, solitary waves, kink- and/or anti-kink-cnoidal periodic wave interaction solutions, which can be utilized to describe various two-place and time-delayed correlated events. As an illustration, a special approximate solution is applied to theoretically capture the salient features of two correlated dipole blocking events in atmospheric dynamical systems.

Solitary Potential in a Space Plasma Containing Dynamical Heavy Ions and Bi-Kappa Distributed Electrons of Two Distinct Temperatures

The heavy ion-acoustic solitary waves (HIASWs) in a magnetized, collisionless, space plasma system (containing dynamical heavy ions and bi-kappa distributed electrons of two distinct temperatures) have been theoretically investigated. The Korteweg-de Vries (K-dV), modified K-dV (MK-dV), and higher-order MK-dV (HMK-dV) equations are derived by employing the reductive perturbation method. The basic features of HIASWs (viz. speed, polarity, amplitude, width, etc.) are found to be significantly modified by the effects of number density and temperature of different plasma species, and external magnetic field (obliqueness). The K-dV and HM-KdV equations give rise to both compressive and rarefactive solitary structures, whereas the MK-dV equation supports only the compressive solitary structures. The implication of our results in some space and laboratory plasma situations are briefly discussed.

An explanation of local fractional variational iteration method and its application to local fractional modified Korteweg-de Vries equation

The variational iteration method was originally proposed to solve non-linear problems of differential equations, this paper shows that it is also a powerful mathematical tool to local fractional differential equations. Two local fractional modified Korteweg-de Vries equations are used as examples to reveal the simple solution process.

Landau damping of dust acoustic solitary waves in nonthermal plasmas

Dust acoustic (DA) solitary and shock structures have been investigated under the influence of Landau damping in a dusty plasma containing two temperature nonthermal ions. Motivated by the observations of Geotail spacecraft that reported two-temperature ion population in the Earth's magnetosphere, we have investigated the effect of resonant wave-particle interactions on DA nonlinear structures. The Korteweg-de Vries (KdV) equation with an additional Landau damping term is derived and its analytical solution is presented. The solution has the form of a soliton whose amplitude decreases with time. Further, we have illustrated the influence of Landau damping and nonthermality of the ions on DA shock structures by a numerical solution of the Landau damping modified KdV equation. The study of the time evolution of shock waves suggests that an initial shock-like pulse forms an oscillatory shock at later times due to the balance of nonlinearity, dispersion, and dissipation due to Landau damping. The findings of the present investigation may be useful in understanding the properties of nonlinear structures in the presence of Landau damping in dusty plasmas containing two temperature ions obeying nonthermal distribution such as in the Earth's magnetotail.

On determination of the source term of a modified KdV equation

On determination of the source term of a modified KdV equation

Linearization of the box–ball system: an elementary approach

Kuniba, Okado, Takagi and Yamada have found that the time-evolution of the Takahashi-Satsuma box-ball system can be linearized by considering rigged configurations associated with states of the box-ball system. We introduce a simple way to understand the rigged configuration of $\mathfrak{sl}_2$-type, and give an elementary proof of the linearization property. Our approach can be applied to a box-ball system with finite carrier, which is related to a discrete modified KdV equation, and also to the combinatorial $R$-matrix of $A_1^{(1)}$-type. We also discuss combinatorial statistics and related fermionic formulas associated with the states of the box-ball systems. A fermionic-type formula we obtain for the finite carrier case seems to be new.

An extended car-following model to describe connected traffic dynamics under cyberattacks

In this paper, the impacts of the potential cyberattacks on vehicles are modeled through an extended car-following model. To better understand the mechanism of traffic disturbance under cyberattacks, the linear and nonlinear stability analysis are conducted respectively. Particularly, linear stability analysis is performed to obtain different neutral stability conditions with various parameters; and nonlinear stability analysis is carried out by using reductive perturbation method to derive the soliton solution of the modified Korteweg de Vries equation (mKdV) near the critical point, which is used to draw coexisting stability lines. Furthermore, by applying linear and nonlinear stability analysis, traffic flow state can be divided into three states, i.e., stable, metastable and unstable states which are useful to describe shockwave dynamics and driving behaviors under cyberattacks. The theoretical results show that the proposed car-following model is capable of successfully describing the car-following behavior of connected vehicles with cyberattacks. Finally, numerical simulation using real values has confirmed the validity of theoretical analysis. The results further demonstrate our model can be used to help avoid collisions and relieve traffic congestion with cybersecurity threats.

Rogue wave-type solutions of the mKdV equation and their relation to known NLSE rogue wave solutions

We present the first four exact rational solutions of the set of rational solutions of the modified Korteweg–de Vries equation. These solutions can be considered as rogue waves of the corresponding equation. Comparison with rogue wave solutions of the nonlinear Schrodinger equation shows a strong analogy between their characteristics, especially for amplitude-to-background ratio. The new solutions may be useful in the theory of rogue waves in shallow water and for light propagation in cubic nonlinear media involving only a few optical cycles.

Multiple soliton solutions for the (3+1) conformable space–time fractional modified Korteweg–de-Vries equations

In the present paper, multiple exact soliton solutions for the old and the newly introduced (3+1)-dimensional modified Korteweg–de-Vries equation (mKdV) will be sought. The mKdV equations considered feature fractional derivative orders in both the space and time variables. A variety of soliton solutions ranging from hyperbolic to periodic function solutions will be constructed using simple ansatze for the equations. Finally, the algebraic equations to be obtained along the way and graphical representations will be carried out by utilizing the Mathematica software.

Nonlinear dust ion acoustic waves behaviors analysis in warm viscous dusty plasma with trapped ions

The nonlinear excitation of a dust ion acoustic (DIA) wave packet in a viscous dusty plasma consisting of Boltzmann distributed electrons, trapped ions, and variable charged dust is investigated. The dependence of the damping rate of the waves on the plasma parameters is discussed via the linear stability analysis. The standard reductive perturbation method is employed to derive the modified Korteweg-de Vries-Burgers equation due to an interplay among the nonlinearity, dispersion, and dissipation effects, and, the non-dissipative case gives the modified Korteweg-de Vries equation. Bifurcation analysis is discussed for the non-dissipative and dissipative systems assuming a Boltzmann distribution for electrons and a vortex-like distribution for ions. The effects of plasma parameters, among which the dusty plasma viscosity ν, trapping ion parameter β, and dust charge variation γ1 on solitary waves (SWs) and shock wave solutions, are discussed. It is observed that parameters ν and β significantly influence the characteristics of nonlinear dust ion acoustic solitary structures. It is seen that without viscosity (ν = 0), the system has the DIA solitary wave solutions, whereas, the viscous system supports DIA shock waves. By increasing the kinematic viscosity, the opportunity for formation of higher energy shock solitary waves increases and the solitary waves become monotonic shock waves.

Soliton excitations in a polariton condensate with defects

To study soliton excitations in a polariton condensate with defects, we use the Gross–Pitaevskii equation and its hydrodynamic form. An extra term is added to take into account the non-equilibrium nature of the polariton condensate and the presence of defects. The reductive perturbation method transforms these hydrodynamic equations into a modified Korteweg–de Vries equation in the long wavelength limit. We linearize this equation and study the soliton linear excitations. We give an analytic expression of traveling excitations using the variation of constants method. In the more general form, we show numerically that the excitations are oscillations, i.e., the amplitude and the width of the dark soliton oscillate simultaneously but in an opposite way.

Stabilization analysis and modified KdV equation of a car-following model with consideration of self-stabilizing control in historical traffic data

In this paper, an extended car-following model which depends not only on the difference of the optimal velocity and the current velocity but also on self-stabilizing control is presented and analyzed in detail. The self-stabilizing control is constructed into the new model by utilizing the historical traffic data (the historical velocity and the historical optimal velocity of the considered vehicle). We derive the stability condition of the extended model against a small perturbation around the homogeneous flow. Theoretical results reveal that the self-stabilizing control in historical optimal velocity difference can further stabilize traffic system on the basis of the self-stabilizing control in historical velocity difference. It is also derived that the time gap between the current traffic data and the historical ones has an important impact on the stability criterion. We clarify the advantages of the self-stabilizing control over the cooperatively driving control and the flexibility in the choice of suppressing in traffic jams. Moreover, from the nonlinear analysis to the proposed model, the historical traffic data dependence of the propagating kink solutions for jam waves is achieved by deriving the modified KdV equation near critical point by using the reductive perturbation method. Finally, theoretical results are confirmed by direct simulations.

Low frequency electrostatic nonlinear structures in an inhomogeneous magnetized non-Maxwellian electron–positron–ion plasma

The properties of low frequency (coupled acoustic and drift wave) nonlinear structures including solitary waves and double layers in an inhomogeneous magnetized electron–positron–ion (EPI) nonthermal plasma with density and temperature inhomogeneities are studied in a simplified way. The nonlinear differential equation derived here for the study of double layers in the inhomogeneous EPI plasma resembles with the modified KdV equation in the stationary frame. But the method used for the derivation of nonlinear differential equation is simple and consistent to give both the stationary solitary waves and double layers. Further, the illustrations show that superthermality κ, drift velocity and temperature inhomogeneity have significant effects on the amplitude, width, and existence range of the structures.

Auxiliary equation method for time-fractional differential equations with conformable derivative

In this paper, the auxiliary equation method is applied to obtain analytical solutions of (2 + 1)-dimensional time-fractional Zoomeron equation and the time-fractional third order modified KdV equation in the sense of the conformable fractional derivative. Given equations are converted to the nonlinear ordinary differential equations of integer order; and then, the resulting equations are solved using a novel analytical method called the auxiliary equation method. As a result, some exact solutions for them are successfully established. The exact solutions obtained by the proposed method indicate that the approach is easy to implement and effective.

A nonstandard numerical method for the modified KdV equation

A linearly implicit nonstandard finite difference method is presented for the numerical solution of modified Korteweg–de Vries equation. Local truncation error of the scheme is discussed. Numerical examples are presented to test the efficiency and accuracy of the scheme.

On unconditional well-posedness for the periodic modified Korteweg–de Vries equation

We prove that the modified Korteweg–de Vries equation is unconditionally well-posed in $H^s({\mathbb{T}})$ for $s\ge 1/3$. For this we gather the smoothing effect first discovered by Takaoka and Tsutsumi with an approach developed by the authors that combines the energy method, with Bourgain's type estimates, improved Strichartz estimates and the construction of modified energies.

Initial–boundary value problems associated with the Ablowitz–Ladik system

We employ the Ablowitz–Ladik system as an illustrative example in order to demonstrate how to analyze initial–boundary value problems for integrable nonlinear differential–difference equations via the unified transform (Fokas method). In particular, we express the solutions of the integrable discrete nonlinear Schrödinger and integrable discrete modified Korteweg–de Vries equations in terms of the solutions of appropriate matrix Riemann–Hilbert problems. We also discuss in detail, for both the above discrete integrable equations, the associated global relations and the process of eliminating of the unknown boundary values.