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1
Content available Difference equations with impulses
EN
Difference equations with impulses are studied focussing on the existence of periodic or bounded orbits, asymptotic behavior and chaos. So impulses are used to control the dynamics of the autonomous difference equations. A model of supply and demand is also considered when Li-Yorke chaos is shown among others.
EN
In this paper we prove the stability of the zero equilibria of two systems of difference equations of exponential type, which are some extensions of an one-dimensional biological model. The stability of these systems is investigated in the special case when one of the eigenvalues is equal to -1 and the other eigenvalue has absolute value less than 1, using centre manifold theory. In addition, we study the existence and uniqueness of positive equilibria, the attractivity and the global asymptotic stability of these equilibria of some related systems of difference equations.
EN
Assume the eigenvalues and the weights are given for a difference boundary value problem and that the form of the boundary conditions at the endpoints is known. In particular, it is known whether the endpoints are fixed (i.e. Dirichlet or non-Dirichlet boundary conditions) or whether the endpoints are free to move (i.e. boundary conditions with affine dependence on the eigenparameter). This work illustrates how the potential as well as the exact boundary conditions can be uniquely reconstructed. The procedure is inductive on the number of unit intervals. This paper follows along the lines of S. Currie and A. Love, Inverse problems for difference equations with quadratic eigenparameter dependent boundary conditions, Quaestiones Mathematicae, 40 (2017), no. 7, 861-877. Since the inverse problem considered in this paper contains more unknowns than the inverse problem considered in the above reference, an additional spectrum is required more often than was the case in the unique reconstruction of the potential alone.
EN
This paper deals with the oscillation of a certain class of second order difference equations with a sub-linear neutral term. Using some inequalities and Riccati type transformation, four new oscillation criteria are obtained. Examples are included to illustrate the main results.
EN
A higher order difference equation is studied. The equation is defined onℤand contains a p-Laplacian and both advance and retardation. Some criteria are established for the existence of infinitely many anti-periodic solutions of the equation. Several consequences of the main theorems are also included. Two examples are provided to illustrate the applicability of the results.
EN
In this paper, we investigate the existence of constant-sign solutions for a nonlinear Neumann boundary value problem involving the discrete p-Laplacian. Our approach is based on an abstract local minimum theorem and truncation techniques.
7
Content available remote On the qualitative study of the nonlinear difference equation ...[wzór]
EN
In this paper, we investigate the global behavior of the following non-linear difference equation ...[wzór] where the coefficients α, β, y, p Є (0,∞) and σ, τ Є N and the initial conditions x-x, x0 x-ω are arbitrary positive real numbers, where ω = max {σ, τ}.
8
Content available remote On the dynamics of the recursive sequence ...[wzór]
EN
In this paper, we investigate the global behavior of the difference equation ...[wzór] where β is a positive parameter and α, γ are non-negative parameters and non-negative initial conditions.
9
Content available remote Application of difference equations to certain tridiagonal matrices
EN
In this paper we present an application of second order homogeneous linear difference equations with constant coefficients to evaluate the determinant of tridiagonal matrices. Comparing the obtained results with a certain alternative approach [1] some formulae for the finite sum are derived.
10
Content available remote Numerical simulation of NO production in a pulverized coal fired furnace
EN
Behaviour of air-coal mixture has been described using the Navier-Stokes equations for the mixture of air and coal particles, accompanied by the turbulence model. The undergoing chemical reactions are described by the Arrhenius kinetics (reaction rate proportional to exp(-E/RT) ). Heat transfer via conduction and radiation has also been considered. The system of partial difference equations is discretized using the finite volume method and the advection upstream splitting method as the Riemann solver. The resulting ordinary differential equations are solved using the 4th order Runge-Kutta method. Results of simulation for typical power production level are presented together with the air staging impact on NO production.
EN
In this paper we investigate the global convergence result, boundedness, and periodicity of solutions of the recursive sequence [formula], where the parameters a, b, c, d and e are positive real numbers and the initial conditions x-2, x-1 and x0 are positive real numbers.
12
Content available remote Euler approximations can destroy unbounded solutions
EN
We show that there are ordinary differential equations in Rd with unbounded solutions, for which the difference equations obtained by using the forward Euler method have all solutions bounded.
EN
An analytical approach to the solution of an infinite slab static problem using the finite strip method is presented. The structure simply supported on its opposite edges is treated as a discrete one. A regular mesh of identical finite strips approximates the continuous structure. This regular slab discretization enables one to derive a fundamental solution for the two-dimensional discrete strip structure in an analytical, closed form. Equilibrium conditions are derived from the finite element method formulation. The set of the infinite number of equilibrium conditions is replaced by one equivalent difference equation. The solution to this equation is the fundamental function, i.e. Green's function for considered slab strip.
PL
W pracy zaprezentowano analityczne rozwiązanie problemu statyki nieograniczonej tarczy metodą pasm skończonych. Tarcza swobodnie podparta na przeciwległych krawędziach jest rozwiązywana jako układ dyskretny. Ciągła struktura jest aproksymowana regularną siatką składającą się z identycznych pasm skończonych. Regularny podział pozwala na wyprowadzenie funkcji fundamentalnych dla dwuwymiarowego układu dyskretnego w analitycznej, zamkniętej formie. Warunki równowagi zostały wyprowadzone zgodnie ze sformułowaniem metody elementów skończonych. Układ równań równowagi składający się z nieskończonej liczby równań został zastąpiony jednym, równoważnym równaniem różnicowym. Rozwiązanie tego równania jest funkcją fundamentalną dla rozpatrywanej tarczy.
EN
In this paper we are concerned with the oscillatory behaviour of solutions of a certain higher order nonlinear neutral type functional difference equation with oscillating coefficient. We obtain two sufficient criteria for oscillatory behaviour.
EN
In this paper, third order difference equations are considered. We study the nonlinear third order difference equation with quasidifferences. Using Riccati transformation techniques, we establish some sufficient conditions for each solution of this equation to be either oscillatory or converging to zero. The result is illustrated with examples.
16
EN
Some difference equations with deviating arguments are discussed in the context of the oscillation problem. The aim of this paper is to present the sufficient conditions for oscillation of solutions of the equations discussed.
EN
Classical solutions of the local Cauchy problem on the Haar pyramid are approximated in the paper by solutions of suitable quasilinear systems of difference equations. The proof of the stability of the difference problem is based on a comparison technique with nonlinear estimates of the Perron type. This new approach to the numerical solving of nonlinear functional differential equations is generated by a quasilinearization method for initial problems. Numerical examples are given.
EN
We study a second order difference equations. We obtain conditions of preservation of solutions when passmg from difference to differential equations.
EN
The aim of this paper is to provide an explicit formula for solutions of the following system of delay difference equations (wzór) where (wzór) ;αn= [n/k] (the symbol [x] stands for entire part of the real number x and k is a fixed positive integer). (An), (Bn), n∈ N, are sequences of square matrices of order m, (fn) is a sequence of vectors from Rm. From this formula conditions for the stability and asymptotic stability of solutions are derived.
EN
In this paper we investigate the oscillatory character of the second order nonlinear difference equations of the forms (wzór) n = 1,2, ... and the corresponding nonhomogeneous equation (wzór) n= 1,2,... via comparison with certain second order linear difference equations where the function f is not necessarily monotonic. The results of this paper are essentially new and can be extended to more general equations.
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