Nonhomogeneous Equations Research Articles

Some Exact Green Function Solutions for Non-Linear Classical Field Theories

We consider some non-linear non-homogeneous partial differential equations (PDEs) and derive their exact Green function solution as a functional Taylor expansion in powers of the source. The kind of PDEs we consider are dispersive ones where the exact solution of the corresponding homogeneous equations can have some known shape. The technique has a formal similarity with the Dyson–Schwinger set of equations to solve quantum field theories. However, there are no physical constraints. Indeed, we show that a complete coincidence with the statistical field model of a quartic scalar theory can be achieved in the Gaussian expansion of the cumulants of the partition function.

Multiplicity of solutions for a nonhomogeneous quasilinear elliptic equation with concave-convex nonlinearities

Abstract We investigate the multiplicity of solutions for a quasilinear scalar field equation with a nonhomogeneous differential operator defined by S u ≔ − div ϕ u 2 + ∣ ∇ u ∣ 2 2 ∇ u + ϕ u 2 + ∣ ∇ u ∣ 2 2 u , Su:= -\hspace{0.1em}\text{div}\hspace{0.1em}\left\{\phi \left(\frac{{u}^{2}+{| \nabla u| }^{2}}{2}\right)\nabla u\right\}+\phi \left(\frac{{u}^{2}+{| \nabla u| }^{2}}{2}\right)u, where ϕ : [ 0 , + ∞ ) → R \phi :\left[0,+\infty )\to {\mathbb{R}} is a positive continuous function. This operator is introduced by Stuart [Two positive solutions of a quasilinear elliptic Dirichlet problem, Milan J. Math. 79 (2011), 327–341] and depends on not only ∇ u \nabla u but also u u . This particular quasilinear term generally appears in the study of nonlinear optics model, which describes the propagation of self-trapped beam in a cylindrical optical fiber made from a self-focusing dielectric material. When the reaction term is concave-convex nonlinearities, by using the Nehari manifold and doing a fine analysis associated on the fibering map, we obtain that the equation admits at least one positive energy solution and negative energy solution, which is also the ground state solution of the equation. We overcome two main difficulties which are caused by the nonhomogeneity of the differential operator S S : (i) the almost everywhere convergence of the gradient for the minimizing sequence { u n } \left\{{u}_{n}\right\} ; (ii) seeking the reasonable restrictions about S S .

Exploring the Multiplication of Resonant Modes in Off-Center-Driven Chladni Plates from Maximum Entropy States

In this study, the resonant characteristics of the off-center-driven Chladni plates were systematically investigated for the square and equilateral triangle shapes. Experimental results reveal that the number of the resonant modes is considerably increased for the plates under the off-center-driving in comparison to the on-center-driving. The Green’s functions derived from the nonhomogeneous Helmholtz equation are exploited to numerically analyze the information entropy distribution and the resonant nodal-line patterns. The experimental resonant modes are clearly confirmed to be in good agreement with the maximum entropy states in the Green’s functions. Furthermore, the information entropy distribution of the Green’s functions can be used to reveal that more eigenmodes can be triggered in the plate under the off-center-driving than the on-center-driving. By using the multiplication of the resonant modes in the off-center-driving, the dispersion relation between the experimental frequency and the theoretical wave number can be deduced with more accuracy. It is found that the deduced dispersion relations agree quite well with the Kirchhoff–Love plate theory.

Evaluation of thermal stresses in transversely isotropic piezoelectric disc with rotation and internal pressure

The paper deals with the analytical solution of transitional stresses in thin rotating disc composed of piezoelectric material under temperature and internal pressure. The stresses are evaluated in the rotating disc by using transition theory of Seth. The electric displacement relations and stresses are computed by using stress strain relations. The non-homogeneous differential equation is derived by substituting the obtained relations into the equilibrium equation. The formulated differential equation is solved with specified boundary conditions, applied pressure, electric displacement and stresses. Obtained results are exhibited graphically, analysed numerically and it is then concluded that transversely isotropic beryl is better than transversely isotropic magnesium material and transversely isotropic piezoelectric materials BaTiO4 and PZT-4.

Nonlinear vibro-acoustic analysis of an axially moving submerged circular cylindrical shell

In this study, the nonlinear vibro-acoustic dynamics and stability of doubly-clamped axially moving cylindrical shell are investigated. The exterior surface of the shell is in contact with fluid and subjected to oblique incident plane sound wave. Donnell’s nonlinear shallow shell theory is used to derive the nonlinear partial differential equation of the cylindrical shell for the radial motion. The Galerkin method is employed to discretize the equations of motion into the set of coupled nonlinear nonhomogeneous ordinary second order differential equations. Considering both driven and companion modes, Multiple Scales Method is used to obtain the response of the system. The effects of sound level, incident angle and axially velocity on the frequency response of the system are studied. The results show that, with increase in the shell velocity transmission loss of the circular shell increases. In addition, at low shell axial velocities simultaneous excitation of the driven and companion modes occurs.

A Semi-Analytical numerical non-stationary creep analysis of a rotating disk made of Polyamid66 under mechanical and thermal loads

A semi-analytical numerical non-stationary creep analysis of constant and variable thickness rotating disks made of polyamide 66 under mechanical and thermal loads is presented using Mendelson’s method of successive approximation. The material properties are time, temperature, and stress-dependent, which vary along the disk’s radius due to effective stress variation and temperature distribution and are represented by Burger’s model. A non-homogeneous differential equation in terms of radial displacement with variable and time-dependent coefficients was established using equilibrium, strain-displacement, and stress-strain relations. First, the initial thermo-elastic stresses at zero time were calculated using the Galerkin method and Hermitian elements. The history of stresses and strains was then calculated using Burger’s viscoelastic model and Prandtl-Reuss relations. To validate the results, an analysis of a disk with constant thickness made of PVDF material was also carried out using the same method employed in this study. Very good agreement of the results was observed in both elastic and creep conditions. Creep analysis was performed for PA66 disks of constant and variable thickness conditions, and the results were compared together. It has been found that the radial displacements and effective stresses are increasing with time for both disks. However, effective stresses and radial displacements of variable-thickness disks are much lower than constant-thickness disks.

Creep stress analysis of Transversely Isotropic Rotating Disc Composed of Piezoelectric Material

If a crystal undergoes mechanical stress, then an electrical potential is developed across its sides; this phenomenon is called piezoelectricity, or the piezoelectric effect. Piezoelectric materials include quartz, zinc oxide (ZnO), lead zirconate titanate (PZT4), and Rochelle salt. There are numerous uses for piezoelectricity in signal and electrical transducers. In this work, transitional and creep stresses are evaluated in a thin disc made up of piezoelectric transversely isotropic solids subjected to rotation. The mathematical expressions of stress components are computed for the rotating disc by using Seth’s transition theory considering the rotation effect in circular disc. The electric displacement relations and various stress components are computed using Hooke’s Law. A non-homogeneous differential equation is obtained by using mathematical relations and the equilibrium equation. The theoretical solution of the differential equation is obtained under specified boundary conditions. Creep stresses are studied for the considered material. The obtained results are shown graphically, analyzed numerically, and concluded with a discussion of the results for transversely isotropic piezoelectric materials such as BaTiO3 and PZT-4, among others. On the basis of all the numerical discussions and graphs, it is concluded that discs composed of transversely isotropic piezoelectric (PZT4 and BaTiO3) materials are more stable than discs composed of transversely isotropic (magnesium and beryl).

Analytical model for flexoelectric sensing of structural response considering bonding compliance

Flexoelectricity has generated huge interest as an alternative to piezoelectricity for developing electromechanical systems such as actuators, sensors, and energy harvesters. This article presents a generic theoretical framework for the sensing mechanism of a flexoelectric sensor bonded to a host beam through an adhesive layer. The model incorporates piezoelectric and flexoelectric effects and considers both shear-lag and peel stresses at the sensor-beam interface. The formulation also includes the electric field gradient terms that are often overlooked. Consistent one-dimensional constitutive relations and governing equations of equilibrium are derived from the electric Gibb’s energy density function and extended Hamilton’s principle. The sensor is assumed to follow the Euler–Bernoulli beam-type membrane and bending deformation behaviour. Closed-form solutions are obtained for the interfacial stresses by analytically solving a seventh-order non-homogeneous ordinary differential equation, satisfying the stress-free boundary conditions at the sensor edges. The induced electric potential at the sensor top is derived by solving a fourth-order differential equation obtained from the charge balance equation, satisfying the electric boundary conditions. For validation, the sensor output is compared with the results of the existing non-rigid bonding piezoelectric sensor model. Numerical results show a significant impact of non-rigid bonding and the electric field gradient terms on the induced electric potential. Further, the importance of bonding compliance on the interfacial stress distributions is illustrated. Finally, the effects of adhesive and transducer thicknesses on the peak amplitudes of interfacial stresses and sensory potential are presented.

Gyrator potential operator and Lp -Sobolev spaces involving Gyrator transform

This paper presents the properties of Gyrator potential operator G μ l and related L p -Sobolev spaces associated with Gyrator transform (GT). The Schwartz-type space S Δ ( R 2 ) is introduced. Various properties of the kernel of GT is studied including its continuity. Pseudo-differential operators A α , q associated with GT is defined and derived it's continuity on S Δ ( R 2 ) . The Gyrator potential operator G μ l is defined as a pseudo-differential operator associated with a precise symbol and obtained certain fruitful properties. The operator G μ l is extended to a space of distributions. Another integral representation of A α , q is obtained and its L p ( R 2 ) -boundedness result is derived. The spaces H α m , p ( R 2 ) and H Δ m , p ( R 2 ) are defined. It is shown that the operator G μ l is an isometry of H Δ m , p ( R 2 ) . An L p -boundedness result for the operator G μ l is proved. We conclude the article by applying some of the results to show that the analytical solution of certain non-homogeneous partial differential equations belong to these spaces.

Solution scheme development of the nonhomogeneous heat conduction equation in cylindrical coordinates with neumann boundary condition by finite difference method

Partial differential heat conduction equations are typically used to determine temperature distribution within any solid domain. The difficulty and complexity of the solution of the equation depend on differential equation characteristics, boundary conditions, coordinate systems, and the number of dependent variables. In the current study, the numerical solution schemes were developed by the Explicit Finite Difference and the Implicit Method- the Crank-Nicolson techniques for the partial differential heat conduction equation including heat generation term described as one-dimensional, time-dependent with the Neumann boundary conditions. The solution schemes were, then, applied to the battery problem including highly varying heat generation. Besides, the solution of the problem was performed by using Matlab pdepe solver to verify the developed schemes. Results suggest that the Crank-Nicolson scheme is unconditionally stable, whereas the explicit scheme is only stable when the Courant-Friedrichs-Lewy condition requirement is less than 0.3404. Comparing the developed schemes to the results obtained from the pdepe solver, the schemes are as reliable as the pdepe solver with certain grid structures. Besides, the developed numerical schemes allow for shorter computational times than the pdepe solver at the same grid structures when considering CPU times.

A quasi-reversibility method for solving nonhomogeneous sideways heat equation

Abstract We consider solving a severely ill-posed problem for determining the surface temperature and heat flux distribution of the nonhomogeneous sideways heat equation by a quasi-reversibility regularization method. An analytical solution is deduced based on the Fourier transform, and then, the logarithmic-type error estimate for the regularized solution is achieved. Finally, three numerical examples, including smooth and non-smooth functions, validate the feasibility and effectiveness of the proposed approach.

Higher order fractal differential equations

This paper provides a summary of the fractal calculus framework. It presents higher-order homogeneous and nonhomogeneous linear fractal differential equations with [Formula: see text]-order. Solutions for these equations with constant coefficients are obtained through the method of variation of parameters and the method of undetermined coefficients. The solution space for higher [Formula: see text]-order linear fractal differential equations is defined, showcasing its non-integer dimensionality. The solutions to [Formula: see text]-order linear fractal differential equations are graphically depicted to illustrate their non-differentiability. Additionally, equations of motion governing the behavior of two masses in fractal time are proposed and solved.

Classifications of bosonic supersymmetric third and fifth order systems

This manuscript explores the extensions and classifications of the bosonic supersymmetric systems. For the third order bosonic superfield equations, four types of integrable supersymmetric extensions are identified, including the B-type (trivial) supersymmetric modified Korteweg–de Vries equation, the supersymmetric Sharma–Tasso–Olver equation, and an A-type (non-trivial) supersymmetric potential Korteweg–de Vries equation. In the case of the fifth order bosonic supersymmetric systems, nine kinds of extensions are discovered, with six being B-type and three being A-type. Notably, several equations such as the supersymmetric Sawada–Kotera equation, the supersymmetric Kaup–Kupershmidt equation and the supersymmetric Fordy–Gibbons equation are classified as B-type extensions. Despite this classification, these supersymmetric systems are shown to be connected to linear integrable couplings. The findings have implications for various fields including string theory and dark matter and highlight the importance of understanding bosonic supersymmetric systems. The obtained supersymmetric systems are solved via bosonization method. Applying the bosonization procedure to every one of supersymmetric systems, one can find various dark equation systems. These dark equation systems can be solved by means of the solutions of the classical equations and some graded linear couplings including homogeneous and nonhomogeneous symmetry equations.

Hölder continuity and Harnack estimate for non-homogeneous parabolic equations

Hölder continuity and Harnack estimate for non-homogeneous parabolic equations

Geometric Approach for Solving First Order Non-homogenous Fuzzy Difference Equation

Geometric Approach for Solving First Order Non-homogenous Fuzzy Difference Equation

Equilibrium solution of two – dimensional non-homogeneous equations in the theory of elastic mixtures

Equilibrium solution of two – dimensional non-homogeneous equations in the theory of elastic mixtures

Equilibrium Solution of Two – Dimensional Non-Homogeneous Equations in the Theory of Elastic Mixtures

Abstract: The problem of plane elasticity for a doubly connected body with inner and outer boundaries in a regular polygonal form with common centre and parallel sides has been studied. The sides of the polygon were exposed to external forces. The nature of the force term was determined by application of complex variable theory. Kolosov’s method of solution was applied to obtain the biharmonic equation of the forcing term. The forces on the particle were studied under 2-dimensions from which the compatibility and equilibrium equations were derived. The compatibility and equilibrium equations were used to derive the force – stress relations. The results shows that there is a significant relationship between the angle of the force term on the plane of the particle and the stress state of the particle, which is in conformity with existing experimental results.

On a nonhomogeneous heat equation on the complex plane

In this paper, we investigate the existence, uniqueness, and asymptotic behaviors of mild solutions of parabolic evolution equations on complex plane, in which the diffusion operator has the form [Formula: see text], where [Formula: see text], the function [Formula: see text] is smooth and subharmonic on [Formula: see text], and [Formula: see text] is the formal adjoint of [Formula: see text]. Our method combines certain estimates of heat kernel associating with the homogeneous linear equation of Raich [Heat equations in [Formula: see text], J. Funct. Anal. 240(1) (2006) 1–35] and a fixed point argument.

Identification of Time-Wise Thermal Diffusivity, Advection Velocity on the Free-Boundary Inverse Coefficient Problem

This paper is concerned with finding solutions to free-boundary inverse coefficient problems. Mathematically, we handle a one-dimensional non-homogeneous heat equation subject to initial and boundary conditions as well as non-localized integral observations of zeroth and first-order heat momentum. The direct problem is solved for the temperature distribution and the non-localized integral measurements using the Crank–Nicolson finite difference method. The inverse problem is solved by simultaneously finding the temperature distribution, the time-dependent free-boundary function indicating the location of the moving interface, and the time-wise thermal diffusivity or advection velocities. We reformulate the inverse problem as a non-linear optimization problem and use the lsqnonlin non-linear least-square solver from the MATLAB optimization toolbox. Through examples and discussions, we determine the optimal values of the regulation parameters to ensure accurate, convergent, and stable reconstructions. The direct problem is well-posed, and the Crank–Nicolson method provides accurate solutions with relative errors below 0.006% when the discretization elements are M=N=80. The accuracy of the forward solutions helps to obtain sensible solutions for the inverse problem. Although the inverse problem is ill-posed, we determine the optimal regularization parameter values to obtain satisfactory solutions. We also investigate the existence of inverse solutions to the considered problems and verify their uniqueness based on established definitions and theorems.

A Search on Integer Solutions to Ternary Non-homogeneous Nonic Diophantine Equation a α(x2+y2)-(2α-1)xy=4αz9

Different sets of integer solutions to the non-homogeneous Nonic Diophantine equation with three unknowns given by α(x2+y2)-(2α-1) xy=4αz9 are presented in this paper.