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A novel method for finding the eigenvalues of a Sturm–Liouville problem is developed. Following the minimalist approach, the problem is transformed to a single first-order differential equation with appropriate boundary conditions. Although the resulting equation is nonlinear, its form allows us to find the general solution by adding a second part to a particular solution. This splitting of the general solution into two parts involves the Schwarzian derivative: hence, the name of the approach. The eigenvalues that correspond to acceptable solutions can be found by requiring the second part to correct the asymptotically diverging behavior of the particular solution. The method can be applied to many different areas of physics, such as the Schrödinger equation in quantum mechanics and stability problems in fluid dynamics. Examples are presented. [ABSTRACT FROM AUTHOR]

Hypergeometric functions of one and many variables play an important role in various branches of modern physics and mathematics. We often encounter hypergeometric functions with indices linearly dependent on a small parameter with respect to which we need to perform Laurent expansions. Moreover, it is desirable that such expansions be expressed in terms of well-known functions that can be evaluated with arbitrary precision. To solve this problem, we use the method of differential equations and the reduction of corresponding differential systems to a canonical basis. In this paper, we are interested in the generalized hypergeometric functions of one variable and in the Appell and Lauricella functions and their expansions in terms of the Goncharov polylogarithms. Particular attention is paid to the case of rational indices of the considered hypergeometric functions when the reduction to the canonical basis involves a nontrivial variable change. The paper comes with a Mathematica package Diogenes, which provides an algorithmic implementation of the required steps. [ABSTRACT FROM AUTHOR]

One kind of stochastic delay differential equation in which the delay term is dependent on a proportion of the current time is the pantograph stochastic differential equation. Electric current collection, nonlinear dynamics, quantum mechanics, and electrodynamics are among the phenomena modeled using this equation. A key idea in physics and mathematics is the well-posedness of a differential equation, which guarantees that the solution to the problem exists and is a unique and meaningful solution that relies continuously on the initial condition and the value of the fractional derivative. Ulam-Hyers stability is a property of equations that states that if a function is approximately satisfying the equation, then there exists an exact solution that is close to the function. Inspired by these findings, in this research work, we established the Ulam-Hyers stability and well-posedness of solutions of pantograph fractional stochastic differential equations (PFSDEs) in the framework of conformable derivatives. In addition, we provided examples to analyze the theoretical results. [ABSTRACT FROM AUTHOR]

In this short note, we investigate a linear stochastic differential equation from mathematical physics, driven by parametric uncertainty. Given the Legendre differential equation with random inputs, the goal is to give a proof of a conjecture posed in a recent paper, concerning the power‐series solution in a Lebesgue sense. By using the finiteness of the moment‐generating function of the equation's coefficient, mean‐square convergence is derived. [ABSTRACT FROM AUTHOR]

The paper concerns a nonlinear second-order parabolic evolution equation, one of the well-known objects of mathematical physics, which describes the processes of high-temperature thermal conductivity, nonlinear diffusion, filtration of liquid in a porous medium and some other processes in continuum mechanics. A particular case of it is the well-known porous medium equation. Unlike previous studies, we consider the case of several spatial variables. We construct and study solutions that describe disturbances propagating over a zero background with a finite speed, usually called 'diffusion-wave-type solutions'. Such effects are atypical for parabolic equations and appear since the equation degenerates on manifolds where the desired function vanishes. The paper pays special attention to exact solutions of the required type, which can be expressed as either explicit or implicit formulas, as well as a reduction of the partial differential equation to an ordinary differential equation that cannot be integrated in quadratures. In this connection, Cauchy problems for second-order ordinary differential equations arise, inheriting the singularities of the original formulation. We prove the existence of continuously differentiable solutions for them. A new example, an analog of the classic example by S.V. Kovalevskaya for the considered case, is constructed. We also proved a new existence and uniqueness theorem of heat-wave-type solutions in the class of piece-wise analytic functions, generalizing previous ones. During the proof, we transit to the hodograph plane, which allows us to overcome the analytical difficulties. [ABSTRACT FROM AUTHOR]

This document is an editorial for a special issue of the journal Mathematics titled "Differential Equations of Mathematical Physics and Related Problems of Mechanics." The special issue covers a range of topics related to differential equations in mathematical physics and mechanics, including wave equations, spectral theory, scattering, and inverse problems. The editorial provides a summary of the published papers in the special issue, highlighting their contributions to the field. The document emphasizes the importance of the special issue in covering both applied and fundamental aspects of mathematics, physics, and their applications in various fields. The author expresses gratitude to the authors, reviewers, assistants, associate editors, and editors for their contributions to the special issue. The report does not provide specific details about the content of the papers or the nature of the special issue. [Extracted from the article]

The Bagley-Torvik equation is an imperative differential equation that considerably arises in various branches of mathematical physics and mechanics. However, very few methods exist for the treatment of the model analytically; in fact, researchers frequently shop for semi-analytical and numerical methods in their studies. Therefore, the main goal of this research is to find the exact analytical solution for the fractional Bagley-Torvik equation fitted with Dirichlet boundary data, as well as a system of fractional Bagley-Torvik equations. Thus, this research aims to show that the modified Adomian decomposition method (MADM) via the proposed two algorithms is a very effective method for treating a class of Bagley-Torvik equations endowed with Dirichlet boundary data. Certainly, MADM is a very powerful approach for solving dissimilar functional equations without the need for either linearization, discretization, perturbation, or even unnecessary restraining postulations. Additionally, the method reveals exact analytical solutions whenever obtainable or closed-form series solutions whenever exact solutions are not feasible. Lastly, some illustrative test problems of the governing model are examined to demonstrate the superiority of the proposed algorithms. [ABSTRACT FROM AUTHOR]

Elliptic functions are of prime importance for physics and mathematics students. We study the Weierstrass elliptic family of functions in the real domain as the solution to an initial value problem. Basic features of the Weierstrass elliptic family and the relation with the Jacobi elliptic functions are derived from the fundamental theory and methods of differential equations. Our approach allows introducing these functions in the undergraduate curriculum very early. reducing time and effort. [ABSTRACT FROM AUTHOR]

The small parameter method allows one to construct solutions of differential equations in the form of power series and has become widespread in mathematical physics. In most cases, these series are asymptotically convergent. The aim of this work is to find conditions for the ordinary convergence of series in powers of a small parameter representing solutions of perturbation theory problems. [ABSTRACT FROM AUTHOR]

In this study, we solve fractional order PDEs with free parameters that regulate wave motion in a low-pass electrical transmission line equation (LPET) using the unified technique. To convert the governing equation into an ordinary differential equation (ODE), we have used a simple linear fractional transformation. The unified technique can therefore be used to find various single and extracting wave solutions to the equation of attention. Using Maple-18 software, all of the established solutions are validated and verified. By selecting appropriate values for the fractional order and free parameters, the two dimensional (2D) and three dimensional (3D) profiles of some of the assimilation solutions demonstrating kink, singular kink, cross kink, bright-dark kink, lump type kink, anti-kink, dark-anti kink, singular periodic, periodic, singular soliton solutions are displayed. The effect of free parameters and fractionality on the dynamical properties of the precise and exploited solutions are graphically illustrated and discussed in detail. We have also compared our results to those found in the literature review. Wherever possible, the judgment demonstrates no significant differences between our realized and published solutions. The results of this investigation show that the adopting technique is both productive and powerful in extracting wave solutions to nonlinear evolution problems that arise in the areas of applied mathematics, mathematical physics, and engineering. [ABSTRACT FROM AUTHOR]

Stochastic fractional differential equations are among the most significant and recent equations in physical mathematics. Consequently, several scholars have recently been interested in these equations to develop analytical approximations. In this study, we highlight the stochastic fractional space Allen-Cahn equation (SFACE) as a major application of this class. In addition, we utilize the simplest equation method (SEM) with a dual sense of Brownian motion to convert the presented equation into an ordinary differential equation (ODE) and apply an effective computational technique to obtain exact solutions. By carefully comparing the derived solutions with solutions from other articles, we prove the distinction of these solutions for their diversity and the discovery of new solutions for SFACE that appear in many scientific fields, such as mathematical biology, quantum mechanics, and plasma physics. The results introduced in this article were obtained by plotting several graphs and examining how noise affects exact solutions using Mathematica and MATLAB software packages. [ABSTRACT FROM AUTHOR]

This article is a tribute to Anatolii Mykhailovych Samoilenko, a renowned Ukrainian mathematician who was born in 1938 and passed away in 2020. Samoilenko made significant contributions to the fields of differential equations, nonlinear mechanics, and the theory of functions. He was known for his work on impulsive differential equations and almost periodic impulsive systems. Samoilenko also developed theories on perturbations and stability of toroidal manifolds, as well as the theory of accelerated convergence. He authored numerous works, including monographs and textbooks, and mentored many young scientists throughout his career. Samoilenko received several awards and honors for his contributions to mathematics. His legacy as a brilliant mathematician, educator, and science organizer will be remembered by those who knew him. [Extracted from the article]

A novel method for finding the eigenvalues of a Sturm–Liouville problem is developed. Following the minimalist approach, the problem is transformed to a single first-order differential equation with appropriate boundary conditions. Although the resulting equation is nonlinear, its form allows us to find the general solution by adding a second part to a particular solution. This splitting of the general solution into two parts involves the Schwarzian derivative: hence, the name of the approach. The eigenvalues that correspond to acceptable solutions can be found by requiring the second part to correct the asymptotically diverging behavior of the particular solution. The method can be applied to many different areas of physics, such as the Schrödinger equation in quantum mechanics and stability problems in fluid dynamics. Examples are presented.

A comprehensive framework has been developed to apply the monomiality principle from mathematical physics to various mathematical concepts from special functions. This paper presents research on a novel family of multivariate Hermite polynomials associated with Apostol-type Frobenius–Euler polynomials. The study derives the generating expression, operational rule, differential equation, and other defining characteristics for these polynomials. Additionally, the monomiality principle for these polynomials is verified. Moreover, the research establishes series representations, summation formulae, and operational and symmetric identities, as well as recurrence relations satisfied by these polynomials. [ABSTRACT FROM AUTHOR]

One of the key tools for many fields of applied mathematics is the integral equations. Integral equations are widely utilized in many models, atmosphere–ocean dynamics, fluid mechanics, mathematical physics, and many other physical and engineering disciplines. A new numerical strategy based on the Bernoulli wavelet is introduced to solve system of Fredholm integral equations of second kind. In this paper, the Bernoulli wavelets are first built. Second, the system of Fredholm integral equations has been reduced into an algebraic system. In order to demonstrate the viability, and accuracy of the suggested Bernoulli wavelet approach, some numerical examples are offered at the end. The derived numerical results are examined with those from other numerical techniques and with exact solutions, demonstrating the superiority of the proposed method over those techniques. The novelty of proposed technique is that it can be extended for the numerical solution of two dimensional integral equations and differential equations appearing in engineering models, however some modifications will be required. [ABSTRACT FROM AUTHOR]

Much of the mathematics with which Felix Klein and Sophus Lie are now associated (Klein's Erlangen Program and Lie's theory of transformation groups) is rooted in ideas they developed in their early work: the consideration of geometric objects or properties preserved by systems of transformations. As early as 1870, Lie studied particular examples of what he later called contact transformations, which preserve tangency and which came to play a crucial role in his systematic study of transformation groups and differential equations. This note examines Klein's efforts in the 1870s to interpret contact transformations in terms of connexes and traces that interpretation (which included a false assumption) over the decades that follow. The analysis passes from Klein's letters to Lie through Lindemann's edition of Clebsch's lectures on geometry in 1876, Lie's criticism of it in his treatise on transformation groups in 1893, and the careful development of that interpretation by Dohmen, a student of Engel, in his 1905 dissertation. The now-obscure notion of connexes and its relation to Lie's line elements and surface elements are discussed here in some detail. [ABSTRACT FROM AUTHOR]

Ionospheric scintillation effects are investigated in the high-latitude conductive collisional ionospheric magnetized (COCOIMA) plasma by calculating the statistical characteristics of multiply scattered radio waves (RW) applying the modified perturbation method. Polarization coefficients in the polar COCOIMA plasma are derived for the first time. Differential equation for a random phase is derived. The variance and the auto-correlation function are obtained for any auto-correlation function of electron density fluctuations considering diffraction effects. Statistical moments contain: complex refractive index, polarization coefficients of both extraordinary and ordinary waves; orientation of an external magnetic field, Pedersen, Halls and longitudinal conductivities, parameters of elongated plasmonic irregularities and the velocity of a plasma flow. The scintillation level of scattered radio waves (RW) in the COCOIMA plasma is computed for the first time using zeroth, 1 st and square root 2nd moments of the power spectra. Oscillations of the scintillation spectrum are caused by the Fresnel filtering effect. It is possible to solve the opposite problem - calculate the velocity of a plasma flow and restore a structure of small-scale inhomogeneities than the Fresnel radius. Numerical simulations are interpreted for 3D anisotropic Gaussian and power-law spectral functions including axial ratio and an inclination angle of prolate plasmonic structures using the IRI model. [ABSTRACT FROM AUTHOR]

This paper presents an approach that allows us for the first time to construct an exact solution of the Wiener–Hopf integral equations on a finite segment for the case of meromorphic functions in Fourier transforms of the kernel. The Wiener–Hopf integral equation is traditionally considered set on a semi-infinite segment. However, in applications, there are often cases of their application specified on a finite segment. For these purposes, approximate methods of applying these integral equations have been developed. However, when considering the Wiener–Hopf integral equations generated by mixed problems of continuum mechanics and mathematical physics in a multilayer medium of finite thickness, it turned out that these integral equations are solved exactly both on semi-infinite and finite segments. The approach is based on a new modeling method in differential equations and in some types of integral equations. It allows the reduction of Wiener–Hopf integral equations to infinite systems of linear algebraic equations that are solved exactly. The obtained result opens up the possibility of constructing exact solutions to boundary value problems for deformable stamps and cracks of a new type in bounded bodies. [ABSTRACT FROM AUTHOR]

This paper proposes a distributed collision-free control scheme for connected and automated vehicles (CAVs) at a non-signalized intersection. We first divide an intersection area into three sections, i.e., the free zone, the platoon zone, and the control zone. In order to enable the following vehicles to track the trajectory of their leading vehicle in the platoon zone and the control zone, as well as to guarantee the desired distance between any two adjacent vehicles, the distributed platoon controllers are designed. In the control zone, each vehicular platoon is taken as a whole to be coordinated via an intersection coordination unit (ICU). To avoid collision between each pair of the conflicting platoons approaching from different directions, a platoon-based coordination strategy is designed by scheduling the arrival time of each leading vehicle of different platoons. Specially, considering traffic efficiency and fuel economy, the optimal control problem of the leading vehicle is formulated subject to the constraint of allowable minimum arrival time, which is derived from coordination with other approaching platoons. The Pontryagin Minimum Principle (PMP) and phase-plane method are applied to find the optimal control sequences. Numerical simulations show the effectiveness of this scheme. [ABSTRACT FROM AUTHOR]

In this article, some sufficient conditions for the existence of positive periodic solutions of a more general indefinite singular differential equation are established. The results are applicable to strong singularities as well as weak singularities. Some results in literature are generalized. [ABSTRACT FROM AUTHOR]

The development of certain aspects of special polynomials in line with the monomiality principle, operational rules, and other properties and their aspects is obvious and indisputable. The study presented in this paper follows this line of research. By using the monomiality principle, new outcomes are produced, and their differential equation and series representation is obtained, which are important in several branches of mathematics and physics. Thus, in line with prior facts, our aim is to introduce the Δ h hybrid special polynomials associated with Hermite polynomials denoted by Δ h H Q m (u , v , w ; h) . Further, we obtain some well-known main properties and explicit forms satisfied by these polynomials. [ABSTRACT FROM AUTHOR]

Based on Fourier analysis, we develop an expression for modeling and simulating nonlinear first order systems. This expression is associated to a nonlinear first order differential equation y = f (x) + g (x) x ′ , where x = x (t) is the dynamical variable, y = y (t) is the driving force, and the f and g functions are the characteristic curves which are associated to dissipative and memory elements, respectively. The model is obtained from the sinusoidal response, specifically by calculating the Fourier analysis of y(t) for x (t) = A 1 sin (ω t) + A 0 , where the model parameters are the Fourier coefficients of the response, and the values of A 0 , A 1 and A 1 ′ = A 1 ω . The same expression is used for two kinds of time-domain simulations: to calculate other driving force y ^ based on a dynamical variable x ^ ; and, to calculate the dynamical variable x ^ based on a driving force y ^ . In both cases, the dynamical variable must remain in the range x ^ ∈ [ A 0 - A 1 , A 0 + A 1 ] . By analyzing this expression, we found an equivalence between the Fourier coefficients and the polynomial regressions of the characteristic curves of f and g. This result allows us to obtain the system modeling and simulation based on the amplitude and phase Fourier spectrum obtained from the Fast Fourier Transform (FFT) of the sampled y n version of y(t). It is shown that this technique has a low computational complexity, and it is expected to be suitable for real-time applications for system modeling, simulation and control, in particular when the explicit expressions of the characteristic curves are unknown. Fourier analysis is a fundamental tool in electronics, mathematics and physics, but to the best of the author's knowledge, no work has found this clear evidence of the connection between the Fourier analysis and a first order differential equation. The aim of this work is to initiate a systematic study on this topic. [ABSTRACT FROM AUTHOR]

A modified form of differential equations is proposed that describes physical processes studied in applied mathematics and mechanics. It is noted that solutions to classical equations at singular points may undergo discontinuities of the first and second kind, which have no physical nature and are not experimentally observed. When new equations describing physical fields and processes are derived, elements with finite dimensions are considered instead of infinitely small elements of the medium. Thus, classical equations include nonlocal functions averaged over the element volume and are supplemented by the Helmholtz equations establishing a relationship between nonlocal and actual physical variables, which are smooth functions having no singular points. Singular problems of the theory of mathematical physics and the theory of elasticity are considered. The obtained solutions are compared with the experimental results. [ABSTRACT FROM AUTHOR]

This study focuses on to bring together a new type of quantum calculus, namely p-calculus, and variational calculus. We give necessary optimality conditions for p-variational problem. Sufficient optimality conditions are also given. [ABSTRACT FROM AUTHOR]

Mathematical functions that establish a relationship between the angles of a right triangle and the lengths of its sides are known as trigonometric functions. In this project, we will explore two of the six trigonometric functions and their properties using the trigonometric circle. Initially, trigonometric functions were defined only for acute angles related to right triangles. To extend the sine and cosine functions to functions whose domain is the entire real line, geometric definitions using the unit circle with radius 1 are often used. Then, the domain of the other trigonometric functions is the real line with some isolated points removed. Modern definitions express trigonometric functions as infinite series or as solutions of differential equations. This allows the extension of the definition of sine and cosine functions to the entire complex plane and the definition of other trigonometric functions on the complex plane with some isolated points removed. This project discusses the use of GeoGebra in studying trigonometric functions, the Law of Sine, and Law of Cosine. GeoGebra is a powerful mathematical software that allows for the visualization and exploration of trigonometric functions. [ABSTRACT FROM AUTHOR]

This article demonstrates how the new Double “NE” integral transform is successfully implemented to obtain the exact solutions of fractional nonlinear partial differential equations by considering specified conditions. Several properties and theorems related to existing conditions, partial derivatives, the double convolution theorem, and others are presented. The new technique with double “NE” integral transform is efficient and accurate in examining exact solutions of FPDEs. To show the applicability of the presented method, some examples are illustrated. [ABSTRACT FROM AUTHOR]

This document is a correction notice for an article titled "On symbology and differential equations of Feynman integrals from Schubert analysis" published in the Journal of High Energy Physics. The authors, Song He, Xuhang Jiang, Jiahao Liu, and Qinglin Yang, discuss the generalization of the "Schubert analysis" method to study symbol letters and differential equations for Feynman integral families in various dimensions. They demonstrate the effectiveness of the method using one-loop integrals and various two-loop planar integral families. The correction notice addresses errors in the affiliations and acknowledgments of the original paper. The article is open access and funded by SCOAP3. [Extracted from the article]

The aim of this paper is to find the exact solutions of the Schrödinger equation for the Manning–Rosen plus Graz separable potential through two different approaches to the problem. We express the irregular/Jost and physical solutions in terms of the special functions of mathematical physics. Numerical results of the phase shifts are obtained by utilising the properties of the Jost function and Fredholm determinants for nucleon–nucleon and nucleon–nucleus systems. The results obtained are in good agreement with earlier works. [ABSTRACT FROM AUTHOR]

In mathematical physics, time-dependent Green’s functions (GFs) are the solutions of differential equations of the first and second time derivatives. Habitually, the time-dependent GFs are Fourier transformed into the frequency space. Then, analytical continuation of the frequency is extended to below or above the real axis. After inverse Fourier transformation, retarded and advanced GFs can be obtained, and there may be arbitrariness in such analytical continuation. In the present work, we establish the differential equations from which the retarded and advanced GFs are rigorously solved. The key point is that the derivative of the time step function is the Dirac δ function plus an infinitely small quantity, where the latter is not negligible because it embodies the meaning of time delay or time advance. The retarded and advanced GFs defined in this paper are the same as the one-body GFs defined with the help of the creation and destruction operators in many-body theory. There is no way to define the causal GF in mathematical physics, and the reason is given. This work puts the initial conditions into differential equations, thereby paving a way for solving the problem of why there are motions that are irreversible in time. [ABSTRACT FROM AUTHOR]

In this article we provide new results for the asymptotic behavior of a time-fractional birth and death process $N_{\alpha}(t)$ , whose transition probabilities $\mathbb{P}[N_{\alpha}(t)=\,j\mid N_{\alpha}(0)=i]$ are governed by a time-fractional system of differential equations, under the condition that it is not killed. More specifically, we prove that the concepts of quasi-limiting distribution and quasi-stationary distribution do not coincide, which is a consequence of the long-memory nature of the process. In addition, exact formulas for the quasi-limiting distribution and its rate convergence are presented. In the first sections, we revisit the two equivalent characterizations for this process: the first one is a time-changed classic birth and death process, whereas the second one is a Markov renewal process. Finally, we apply our main theorems to the linear model originally introduced by Orsingher and Polito [23]. [ABSTRACT FROM AUTHOR]

In recent years, much attention has been paid to the role of special matrix polynomials of a real or complex variable in mathematical physics, especially in boundary value problems. In this article, we define a new type of matrix-valued polynomials, called the first Appell matrix polynomial of two complex variables. The properties of the newly definite matrix polynomial involving, generating matrix functions, recurrence relations, Rodrigues' type formula and integral representation are investigated. Further, relevant connections between the first Appell matrix polynomial and various matrix functions are reported. The current study may open the door for further investigations concerning the practical applications of matrix polynomials associated with a system of differential equations. [ABSTRACT FROM AUTHOR]

Recently, solving differential equations by deep neural networks has attracted lots of attention, however, when the solution of differential equations has localized areas such as the rogue waves, the classical physics-informed neural networks (PINNs) cannot guarantee its prediction accuracy. In this paper, we propose two neural networks methods: mix-training physics-informed neural networks (MTPINNs) and prior information mix-training physics-informed neural networks (PMTPINNs), two deep learning models with more approximation ability based on PINNs. A series of numerical experiments show that the learning efficiency and absolute error accuracy of our proposed model can be improved significantly. The PMTPINNs model can so as to make up for the shortcomings of PINNs in this aspect. Furthermore, by testing the robustness of these two methods, for two kinds of rogue waves of the Hirota equation, it is surprising that these models also have good performance and thereby may provide more possibilities for solving mathematical physics problems better. • Two neural networks methods have been proposed to study the high-order rogue waves of the Hirota equation. • The MTPINNs and the PMTPINNs yield considerable improvement in accuracy and have good robustness. • We propose the adjusted PMTPINNs+, which further improves the learning and prediction ability of PMTPINNs. [ABSTRACT FROM AUTHOR]

Many application problems in physics and financial mathematics have been modeled by differential equations of boundary value problems defined on large or infinite domains. Numerical solutions are often necessary since analytic solutions to such problems are rarely available. A Kevin's transformation that transforms an infinite domain to a finite one is one of approaches in dealing with infinite domain problems. In this paper, studies are carried out on when and how the transformation method can be applied to solve differential equations defined on large or infinite domains. Some new coupled transformation methods are proposed with convergence analysis. The proposed methods work well for certain problems, for example, that have reasonably decay rates. With the new approach, no artificial or truncated boundary conditions are needed. The key idea is to use a transformation to divide an infinite domain problem to a coupled two-domain problem that can be solved simultaneously. Convergence analysis provided some insights about conditions that the new methods can be applied to. Numerical examples are also presented to confirm the algorithm designs and analysis. [ABSTRACT FROM AUTHOR]