Dimensional Equation Research Articles

On optical solitons of the (1 1)-dimensional Biswas-Milovic equation having Kerr law and parabolic-law with weak non-local nonlinearity in the presence of spatio-temporal dispersion

In this study, an effort has been made to obtain optical soliton solutions of the (1+1)-dimensional Biswas-Milovic equation which was introduced by Biswas and Milovic in 2010, having Kerr law and parabolic-law with weak non-local nonlinearity in the presence of spatio-temporal dispersion, which is one of the important models for nonlinear optics. Although, the model is an equation that has been studied by many researchers, the fact that the form to be examined has not been studied before. As a general algorithm, first converting the model to nonlinear ordinary differential form with a complex wave transformation, then obtaining candidate optical soliton solutions by utilizing the new Kudryashov technique, determining the ones that satisfy the main equation from these solutions as the exact solution, and in order to better understand the obtained solutions by making graphical presentation and providing the necessary comments constitute the main framework of the article.

Soliton solutions for a (3 + 1)-dimensional nonlinear integrable equation

Soliton solutions for a (3 + 1)-dimensional nonlinear integrable equation

Symmetry and complexity: A Lie symmetry approach to bifurcation, chaos, stability and travelling wave solutions of the (3+1)-dimensional Kadomtsev-Petviashvili equation

This work delves into the investigation of the nonlinear dynamics pertaining to the (3+1)-dimensional Kadomtsev-Petviashvili equation, which describes the propagation of long-wave with dissipation and dispersion in nonlinear media. The research entails an exploration of symmetry reductions using Lie group analysis, an analysis of the dynamical system’s characteristics through bifurcation phase portraits, and a study of the perturbed dynamical system’s dynamic behavior through chaos theory. Chaotic behavior is identified using various tools for detecting chaos, including the Lyapunov exponent, 3D phase portrait, Poincare map, time series analysis, and an exploration of the presence of multistability in the autonomous system under different initial conditions. Additionally, the research applies the unified Riccati equation expansion method to solve the considered equation analytically and constructs the general solutions of solitary wave solutions such as trigonometric function solutions, periodic and singular soliton solutions. These solutions come with their associated constraint conditions and are demonstrated through visual representations in the form of 2D, 3D, and density plots with carefully selected parameters. Furthermore, the stability analysis of the considered equation is also discussed and shown graphically. The results of this work are relevant and have applications in describing the propagation of long-wave with dissipation and dispersion in nonlinear media.

Fast estimation of a large TVP-VAR model with score-driven volatilities

This paper proposes a fast approach to estimating a large time-varying parameter vector autoregressive (TVP-VAR) model. Based on a score-driven modeling framework, we first assume that the time-varying variances of random errors in each equation of the TVP-VAR are score-driven, and then propose filtering and smoothing procedures to estimate time-varying parameters and time-varying volatilities. We show that under the forgetting factors, the filtering estimation of time-varying parameters is equivalent to an equation-by-equation estimator, significantly reducing the dimension of state space and thus delivering fast estimation. Moreover, a fast smoothing estimation can be derived, avoiding the inverse of the super-high dimensional state equation covariance matrix. We provide dynamic model averaging (selection) and maximum likelihood estimates for forecasting and inference. Our simulation study shows that the proposed method is more accurate than the popular methods and enjoys tremendous computational gain from the equation-by-equation estimator. Finally, we conduct an empirical study on the dynamic connectedness of global stock markets, demonstrating the merits of our methods in real-time and ex-post analysis.

Diverse optical soliton solutions of two space-time fractional nonlinear evolution equations by the extended kudryashov method

This study investigates the inclusive optical soliton solutions to the (2+1)-dimensional nonlinear time-fractional Zoomeron equation and the space-time fractional nonlinear Chen-Lee-Liu equation using the extended Kudryashov technique. The beta derivative is used to conduct the fractional terms and investigate wide-spectral soliton solutions to the considered models. The obtained solutions yield a variety of typical soliton shapes, including ant-peakon soliton, V-shaped soliton, anti-bell-shaped soliton, kink soliton, periodic soliton, singular periodic soliton for the specific value of the parameters. The three-dimensional, contour, and two-dimensional graphs of the derived solitons have been plotted to illustrate the structure, propagation, and influence of the fractional parameter. It is observed that the fractional parameter affects the amplitudes and periods of certain solitons. The precision of the acquired solutions is confirmed by reintroducing them into the original equation using Mathematica. The findings of this study indicate that the employed method has the capability of yielding compatible, creative, and useful solutions for diverse nonlinear evolution equations with fractional derivatives. This approach could introduce novel ways for unraveling other nonlinear equations and have implications in diverse sectors of nonlinear science and engineering.

Spatial self-bending soliton phenomenon of (2+1) dimensional bidirectional Sawada-Kotera equation

In this study, we delve into the phenomenon of spatial self-bending solitons within the context of the (2+1)-dimensional bidirectional Sawada-Kotera equation. By employing the Hirota bilinear method, the bilinear form of the (2+1)-dimensional bidirectional Sawada-Kotera equation can be obtained. Through specific parameter constraints (eAjs=0), we establish the N-soliton solution and subsequently derive the spatial self-bending soliton. The curvature of this spatial self-bending soliton is also elucidated. Additionally, we explore the interaction between the spatial self-bending soliton and respiratory waves, along with the interaction between the spatial self-bending soliton and higher-order lump waves through the method of the long wave limit.

Implicit Runge‐Kutta with spectral Galerkin methods for the fractional diffusion equation with spectral fractional Laplacian

AbstractAn efficient numerical method with high accuracy both in time and in space is proposed for solving ‐dimensional fractional diffusion equation with spectral fractional Laplacian. The main idea is discretizing the time by an ‐stage implicit Runge‐Kutta method and approximating the space by a spectral Galerkin method with Fourier‐like basis functions. In view of the orthogonality, the mass matrix of the spectral Galerkin method is an identity and the stiffness matrix is diagonal, which makes the proposed method is efficient for high‐dimensional problems. The proposed method is showed to be stable and convergent with at least order in time, when the implicit Runge‐Kutta method with classical order () is algebraically stable. As another important contribution of this paper, we derive the spatial error estimate with optimal convergence order which depends on the regularity of the exact solution but not on the fractional parameter . This improves the previous result which depends on the fractional parameter . Numerical experiments verify and complement our theoretical results.

Solutions of Time Fractional (1 + 3)-Dimensional Partial Differential Equations by the Natural Transform Decomposition Method (NTDM)

The current study employs the natural transform decomposition method (NTDM) to test fractional-order partial differential equations (FPDEs). The present technique is a mixture of the natural transform method and the Adomian decomposition method. For the purpose of checking the precis of our technique, some examples are offered, and the series solutions of these equations are introduced by using NTDM. The outcome shows that the suggested approach is very active and straightforward for obtaining a series solutions of FPDEs and is more accurate if we compare it with existing methods.

General Soliton and (Semi-)Rational Solutions of a (2+1)-Dimensional Sinh-Gordon Equation

In this paper, we investigate solutions of a (2+1)-dimensional sinh-Gordon equation. General solitons and (semi-)rational solutions are derived by the combination of Hirota’s bilinear method and Kadomtsev-Petviashvili hierarchy reduction approach. General solutions are expressed as Ntimes N Gram-type determinants. When the determinant size N is even, we generate solitons, line breathers, and (semi-)rational solutions located on constant backgrounds. In particular, through the asymptotic analysis we prove that the collision of solitons are completely elastic. When N is odd, we derive exact solutions on periodic backgrounds. The dynamical behaviors of those derived solutions are analyzed with plots. For rational solutions, we display the interaction of lumps. For semi-rational solutions, we find the interaction solutions between lumps and solitons.

Dynamics of Lump, Breather, Two-Waves and Other Interaction Solutions of (2+1)-Dimensional KdV Equation

Dynamics of Lump, Breather, Two-Waves and Other Interaction Solutions of (2+1)-Dimensional KdV Equation

On the unique ergodicity for a class of 2 dimensional stochastic wave equations

We study the global-in-time dynamics for a stochastic semilinear wave equation with cubic defocusing nonlinearity and additive noise, posed on the 2 2 -dimensional torus. The noise is taken to be slightly more regular than space-time white noise. In this setting, we show existence and uniqueness of an invariant measure for the Markov semigroup generated by the flow over an appropriately chosen Banach space. This extends a result of the second author [Comm. Math. Phys. 377 (2020), pp. 1311–1347] to a situation where the invariant measure is not explicitly known.

Deep neural networks learning forward and inverse problems of two-dimensional nonlinear wave equations with rational solitons

In this paper, we investigate the forward problems on the data-driven rational solitons for the (2+1)-dimensional Kadomtsev–Petviashvili-I (KP-I) equation and spin-nonlinear Schrödinger (spin-NLS) equation via the deep neural networks learning. Moreover, the inverse problems of the (2+1)-dimensional KP-I equation and spin-NLS equation are studied via deep learning. The main idea of the data-driven forward and inverse problems is to use the deep neural networks with the activation function to approximate the solutions of the considered (2+1)-dimensional nonlinear wave equations by optimizing the chosen loss functions related to the considered nonlinear wave equations.

Covariance models and Gaussian process regression for the wave equation. Application to related inverse problems

In this article, we consider the general task of performing Gaussian process regression (GPR) on pointwise observations of solutions of the 3 dimensional homogeneous free space wave equation. In a recent article, we obtained promising covariance expressions tailored to this equation: we now explore the potential applications of these formulas. We first study the particular cases of stationarity and radial symmetry, for which significant simplifications arise. We next show that the true-angle multilateration method for point source localization, as used in GPS systems, is naturally recovered by our GPR formulas in the limit of the small source radius. Additionally, we show that this GPR framework provides a new answer to the ill-posed inverse problem of reconstructing initial conditions for the wave equation from a limited number of sensors, and simultaneously enables the inference of physical parameters from these data. We finish by illustrating this “physics informed” GPR on a number of practical examples.

Exploring lump soliton solutions and wave interactions using new Inverse $$(G'/G)$$-expansion approach: applications to the (2+1)-dimensional nonlinear Heisenberg ferromagnetic spin chain equation

Exploring lump soliton solutions and wave interactions using new Inverse $$(G'/G)$$-expansion approach: applications to the (2+1)-dimensional nonlinear Heisenberg ferromagnetic spin chain equation

Nonlocal symmetries and solutions of the (2+1) dimension integrable Burgers equation

The conservation laws of low-dimensional partial differential equations have been employed by Lou et al. to construct various high-dimensional equations, particularly focusing on high-dimensional integrable equations. However, solving these high-dimensional equations poses significant challenges. In this paper, the (2+1)-dimensional Burgers equation is studied by means of nonlocal symmetry method for the first time. For this high-dimensional equation, we establish a link with the exact solution of the (1+1)-dimensional Burgers equation through nonlocal symmetry. Furthermore, we successfully construct multiple exact solutions for the high-dimensional Burgers equation by leveraging the exact solution of the low-dimensional counterpart. We also give the corresponding images of several solutions to study the dynamic behavior of the equations.

Numerical Solution for the Heat Equation Using Forward Time Centered Space Difference Method

Abstract: In this paper, the forward time centered space is applied to a simple problem involving one dimensional heat equation. Numerical solution to the heat equation using forward time centered space difference equation is obtained. The method of solving the problem is implemented by using Python Programming. We have discussed the local truncation error and stability analysis of explicit forward time centered space difference method of heat equation.

Breathers, Soliton and Hybrid Solutions for generalized (2＋1) dimensional Soliton Equation

This article studies lump and its interaction solutions, breather and solitary wave solutions for generalized (2＋1) dimensional Soliton equation by using direct method based on Hirota’s bilinear form. Lump and its interaction solutions are obtained by assuming test function as a combination of positive, trigonometric and exponential functions. Peak and depth values of lump solutions are also determined using extreme points. 3D, 2D and contour plots are given to comprehend the physical features of these solutions.

Periodic, n-soliton and variable separation solutions for an extended (3+1)-dimensional KP-Boussinesq equation

An extended (3+1)-dimensional Kadomtsev–Petviashvili–Boussinesq equation is studied in this paper to construct periodic solution, n-soliton solution and folded localized excitation. Firstly, with the help of the Hirota’s bilinear method and ansatz, some periodic solutions have been derived. Secondly, taking Burgers equation as an auxiliary function, we have obtained n-soliton solution and n-shock wave. Lastly, we present a new variable separation method for (3+1)-dimensional and higher dimensional models, and use it to derive localized excitation solutions. To be specific, we have constructed various novel structures and discussed the interaction dynamics of folded solitary waves. Compared with the other methods, the variable separation solutions obtained in this paper not only directly give the analytical form of the solution u instead of its potential u_y, but also provide us a straightforward approach to construct localized excitation for higher order dimensional nonlinear partial differential equation.

Hybrid and physical interaction phenomena solutions to the Hirota bilinear equation in shallow water waves theory

The purpose of this research paper is to investigate the (3+1)-dimensional Hirota bilinear equation that arises in nonlinear waves in fluid dynamics, plasma physics and shallow water waves. We use Hirota’s bilinear approach and a long-wave method to explore the dynamical features of the suggested equation. Multiple M-lump waves mixed with soliton solutions are constructed. Also, the breather wave and its interaction with one-soliton and M-lump waves are derived. These solutions are believed to play a role in understanding the dynamical aspects of the (3+1)-dimensional Hirota bilinear equation.

Global energy-preserving local mesh-refined S-FDTD schemes for two dimensional Maxwell's equations in Drude metamaterials

Modeling electromagnetic propagation in metamaterials is of importance in many applications. Designing efficient local mesh refinements is crucial to improve the resolution capacity of solution for solving Maxwell's equations within metamaterials and it is a difficult task to develop local mesh-refined schemes for preserving global energy across the interfaces between coarse and fine meshes. In this paper, we develop two global energy-preserving local mesh-refined splitting FDTD schemes for Maxwell's equations with Drude model. By combining with the energy-conserved splitting FDTD methods, the local mesh-refined interface schemes are established on the interfaces of coarse and fine meshes, which ensure global energy preserving. We prove that the developed GEP-LMR-S-FDTD schemes satisfy global energy conservation and are unconditionally stable. Meanwhile, fast implementation of the GEP-LMR-S-FDTD schemes is investigated to compute the metamaterial electromagnetic problems. Numerical experiments show the excellent performance of the schemes.