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EN
In this article, the solvability of fractional neutral differential equation involving ψ−Caputo fractional operator is considered usinga Krasnoselskii’s fixed point approach. Also, we establish the uniquenessof the solution under certain conditions. Ulam stabilities for the proposedproblem are discussed. Finally, examples are displayed to aid the applicability of the theory results.
EN
The article presents an approximate method of solving the problem of statics of sandwich elements with deep-profiled facings. This method is compared with the widely accepted theory of sandwich beams. The example of uniformly loaded, simply-supported, single-span sandwich beam is presented. The results of displacements, internal forces and stresses obtained by both methods are compared. The results confirm the good compliance of the presented solutions, in particular in terms of displacements.
EN
We study a nonlocal problem for ordinary differential equations of 2n-order with involution. Spectral properties of the operator of this problem are analyzed and conditions for the existence and uniqueness of its solution are established. It is also proved that the system of eigenfunctions of the analyzed problem forms a Riesz basis.
EN
In this study we introduced and tested retarded conformable fractional integral inequalities utilizing non-integer order derivatives and integrals. In line with this purpose, we used the Katugampola type conformable fractional calculus which has several practical properties. These inequalities generalize some famous integral inequalities which provide explicit bounds on unknown functions. The results provided here had been implemented to the global existence of solutions to the conformable fractional differential equations with time delay.
EN
In the paper we investigate slice holomorphic functions F : Cn→C having bounded L-index in a direction, i.e. these functions are entire on every slice {z0 +tb : t∈C} for an arbitrary z0∈Cn and for the fixed direction b∈Cn \ {0}, and (∃m0∈Z+) (∀m∈Z+) (∀z∈Cn) the following inequality holds [wzór], where L : Cn→R+ is a positive continuous function, [wzór] for p≥2. Also, we consider index boundedness in the direction of slice holomorphic solutions of some partial differentia equations with partial derivatives in the same direction. There are established sufficient conditions providing the boundedness of L-index in the same direction for every slie holomorphic solutions of these equations.
EN
The paper presents new methods of construction of the Lyapunov function for some sets of linear extensions of dynamic systems on torus.The paper is divided into two parts. The first part contains a brief theoretical introduction. In the second part are presented results of study and examples.
EN
The paper presents the theorems about regularity of systems of differential equations. The paper is divided into two parts. The first part contains a theoretical introduction. The second part contains theorems which allows to determine the regularity of the system using the generalized Lyapunov function.
8
Content available remote Mathematical model of bats’ subpopulations development
EN
The paper deals with the description of the mathematical model of bats’ subpopulations and fission-fusion societies development. The model is based on the system of ordinary differential equations. Bats’ behaviour and their searching strategy is presented on the basis of cavity roosting bats living in Białowieża Forest located in Poland. Theoretical results are illustrated by a computer simulation and its comparison with biological remarks.
PL
Artykuł dotyczy opisu matematycznego modelu subpopulacji nietoperzy oraz rozwoju procesu zasiedlania nowych dziupli. Model oparty jest na systemie równań różniczkowych zwyczajnych. Zachowania nietoperzy i ich strategie poszukiwań przedstawiono na podstawie obserwacji nietoperzy zamieszkujących dziuple w Puszczy Białowieskiej. Wyniki teoretyczne ilustruje symulacja komputerowa i jej porównanie z uwagami biologicznymi.
EN
In the paper the linear time-invariant fractional-order models of the separated wheel closed-loop electrical drive of the autonomous platform are considered. As a reference model one considers the classical model described by the second-order linear difference equation. Two discrete-time fractional-order models are considered: non-commensurate and commensurate. According to the sum of the squared error criterion (SSE) one compares two-parameter integer-order model with the four-parameter non-commensurate and three-parameter commensurate fractional-order ones. Three mathematical models are built and simulated. The computer simulation results are compared with measured velocity of the real autonomous platform separate wheel closed-loop electrical drive.
EN
Solution of a dynamic system is commonly demanding when analytical approaches are used. In order to solve numerically, describing the motion dynamics using differential equations is becoming indispensable. In this article, Newton’s second law of motion is used to derive the equation of motion the governing equation of the dynamic system. A quarter model of the suspension system of a car is used as a case and sinusoidal road profile input was considered for modeling. The state space representation was used to reduce the second order differential equation of the dynamic system of suspension model to the first order differential equation. Among the available numerical methods to solve differential equations, Euler method has been employed and the differential equation is coded MATLAB. The numerical result of the second degree of freedom, quarter suspension system demonstrated that the approach of using numerical solution to a differential equation of dynamic system is suitable to easily simulate and visualize the system performance.
PL
Praca dotyczy zastosowania metody wielokrokowej Geara oraz wybranych metod niejawnych IRK do rozwiązania układu równań różniczkowych zwyczajnych, opisujących obwód zawierający cewkę nieliniową. Zostanie przedstawiony model takiej cewki oraz jej opis za pomocą wybranych zmiennych stanu. Zostanie również przedstawiony program do badania dynamiki cewki opracowany w języku C#, w którym zaimplementowano metody niejawne RK: RADAU IIA, Gaussa-Legendre'a, Lobatto III C oraz metody wielokrokowe.
EN
The work concerns the application of the multistep Gear and selected IRK implicit methods to solve the system of ordinary differential equations describing a circuit containing non-linear coil. In this paper - model of the coil and its description with the use of selected state variables will also be presented. This paper will also show application for dynamics examination of the circuit written in C#, in which the following implicit RK methods were implemented: Radau IIA, Gauss-Legendre, Lobatto III C and the multistep method.
EN
The theory of generalized thermoelasticity in the context of the Green-Naghdi model -II (thermoelasticity without energy dissipation) is studied for an infinite circular cylindrical cavity subjected to two different cases of thermoelastic interactions when the radial stress is zero for (a) maintaining constant temperature and (b) temperature is varying exponentially with time. The Laplace transform from time variable is used to the governing equations to formulate a vector matrix differential equation which is then solved by the eigen value approach. Numerical computations for the displacement component, temperature distribution and components of thermal stress have been made and presented graphically.
EN
This paper is concerned with the controllability of nonlinear fractional delay dynamical systems with implicit fractional derivatives for multiple delays and distributed delays in control variables. Sufficient conditions are obtained by using the Darbo fixed point theorem. Further, examples are given to illustrate the theory.
EN
In this paper, a semi-analytical solution for free vibration differential equations of curved girders is proposed based on their mathematical properties and vibration characteristics. The solutions of in-plane vibration differential equations are classified into two cases: one only considers variable separation of non-longitudinal vibration, while the other is a synthesis method addressing both longitudinal and non-longitudinal vibrationusing Rayleigh’s modal assumption and variable separation method. A similar approach is employed for the out-of-plane vibration, but further mathematical operations are conducted to incorporate the coupling effect of bending and twisting. In this case study, the natural frequencies of a curved girder under different boundary conditions are obtained using the two proposed methods, respectively. The results are compared with those from the finite element analysis (FEA) and results show good convergence.
PL
Jako wspólna płaszczyzna wcześniejszych badań, wynikowe równania różniczkowe drgań opracowane na podstawie statycznych równań różniczkowych Vlasowa dotyczących zakrzywionych dźwigarów nie posiadają ścisłego wyprowadzenia [1-7]. Ostatnimi czasy zastosowano metody fizyki matematycznej w celu wyprowadzenia równań różniczkowych drgań zakrzywionych dźwigarów oraz w celu udowodnienia równań, lecz rozwiązanie nadal nie zostało opracowane [8-16]. Równania różniczkowe drgań zakrzywionych dźwigarów zostały wyprowadzone zgodnie z zasadą Hamiltona oraz równaniem Lagrange’a i mają zastosowanie jedynie do zakrzywionych belek Timoshenko w osiowym układzie współrzędnych. W niniejszej pracy zaproponowano pół-analityczne rozwiązanie dla równań różniczkowych swobodnych drgań zakrzywionych dźwigarów, w oparciu o ich właściwości matematyczne i charakterystyki drgań. Przede wszystkim przyjęto podstawowe założenia dla zakrzywionego dźwigara, w tym 1) zakrzywiony dźwigar ma stały przekrój i promień krzywizny, jak również jednorodny materiał; 2) przekrój poprzeczny zakrzywionego dźwigara ma pionową oś symetrii, a centroid zbiega się z środkiem ścinania; 3) promień krzywizny zakrzywionego dźwigara jest znacznie większy niż rozmiar, długość i wysokość przekroju poprzecznego.
EN
In the paper we found the coefficient relations for which the differential system of the special case of the Stewart-Levin model has a two-parameter family of solutions and the general solution in an analytical form. This model describes the dynamics of the unstable strains of two micro-organisms when the specific consumption rate of a substrate by both the plasmid-bearing and the plasmid-free organisms are given by the Mono function, and the half-saturation constants are equal. The example shows the procedure for finding concrete relations connecting the unknown functions and time. Also, a relation between the functions of the microorganisms’ densities was built. The visualization of all three functions is presented. The coincidence in the graphs of the functions built by analytical and numerical methods is shown.
PL
W artykule określono relacje współczynników, dla których układ różniczkowy specjalnego modelu Stewart-Levina ma dwuparametryczne rozwiązanie i ogólne rozwiązanie w postaci analitycznej. Model ten opisuje dynamikę niestabilnych szczepów dwóch mikroorganizmów, gdy stopień zużycia substratu zarówno przez mikroorganizm posiadający wektor nośnikowy, jak i wektor pusty jest określony za pomocą funkcji Mono przy założeniu, że stałe połowicznego wysycenia są równe. Przykład ten prezentuje procedurę odkrywania specyficznych powiązań łączących nieznane dotąd funkcje w danym przedziale czasowym. Dodatkowo w artykule przedstawiono związek między gęstością mikroorganizmów, a pełnioną przez nie funkcją. Zależności przedstawione na wykresach otrzymano przy użyciu metod analitycznych i numerycznych.
16
Content available remote Invariant embedding method for rotor parameters identification of induction motors
EN
The use of theory of invariant embedding for identification of internal parameters of three-phase squirrel-cage induction motor which cannot be directly measured is considered in article. A system of nonlinear differential equations N. Distefano is analytically presented, the numerical solution of which allows to obtain the values of such parameters as resistance and rotor windings inductance.
PL
W artykule podjęta próba wykorzystania inwariantnej teorii zanurzenia dla identyfikacji wewnętrznych parametrów klatkowego trójfazowego asynchronicznego silnika, których nie da się zmierzyć bezpośrednio. Został przedstawiony system nieliniowych równań różniczkowych N. Distefano, rozwiązanie których pozwala uzyskać wartości takich parametrów jak aktywna rezystancja i indukcyjność rotora.
EN
In the present paper we provide some existence results and Ulam’s type stability concepts for the Darboux problem of partial fractional random differential equations in Banach spaces, by applying the measure of noncompactness and a random fixed point theorem with stochastic domain.
EN
Our aim in this work is to study the existence of solutions of first and second order for neutral functional differential equations with state-dependent delay. We use the Mönch’s fixed point theorem for the existence of solutions and the concept of measures of noncompactness.
EN
In this paper, a numerical solution of mass transfer effects on an unsteady free convection flow of an incompressible electrically conducting viscous dissipative fluid past an infinite vertical porous plate under the influence of a uniform magnetic field considered normal to the plate has been obtained. The non-dimensional governing equations for this investigation are solved numerically by using the Ritz finite element method. The effects of flow parameters on the velocity, temperature and concentration fields are presented through the graphs and numerical data for the skin-friction, Nusselt and Sherwood numbers are presented in tables and then discussed.
20
Content available remote Painlevé equation PII and strongly normal extensions
EN
The aim of this paper is to show that if F is a differential field and y is a PII transcendent such that tr.deg. F=2, then every constant in F is in F. We also show that in this case, F is not contained in any strongly normal extension.
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