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EN
In this research work, we consider a thin, simply supported rectangular plate defined as 0 ≤ x ≤ a, 0 ≤ y ≤ b, 0 ≤ z ≤ c and determine the thermal stresses by using a thermal bending moment with the help of a time dependent fractional derivative. The constant temperature is prescribed on the surface y = 0 and other surfaces are maintained at zero temperature. A powerful technique of integral transform is used to find the analytical solution of initial-boundary value problem of a thin rectangular plate. The numerical result of temperature distribution, thermal deflection and thermal stress component are computed and represented graphically for a copper plate.
EN
The paper deals with an optimal control problem in a dynamical system described by a linear differential equation with the Caputo fractional derivative. The goal of control is to minimize a Bolza-type cost functional, which consists of two terms: the first one evaluates the state of the system at a fixed terminal time, and the second one is an integral evaluation of the control on the whole time interval. In order to solve this problem, we propose to reduce it to some auxiliary optimal control problem in a dynamical system described by a first-order ordinary differential equation. The reduction is based on the representation formula for solutions to linear fractional differential equations and is performed by some linear transformation, which is called the informational image of a position of the original system and can be treated as a special prediction of a motion of this system at the terminal time. A connection between the original and auxiliary problems is established for both open-loop and feedback (closed-loop) controls. The results obtained in the paper are illustrated by examples.
3
Niejednoznaczności wyznaczania ułamkowej potęgi wektora wirującego
PL
W pracy przedstawiono problem niejednoznaczności wyznaczania pochodnych ułamkowego rzędu wektora wirującego. Jest to związane z określeniem ułamkowej potęgi liczby zespolonej.
EN
The paper presents problems of ambiguity of calculation of fractional derivatives for the rotating vector. This is related to the determining of fractional power of the imaginary number.
EN
The α-order fractional derivative of the Dirichlet η function is computed in order to investigate the behavior of the fractional derivative of the Riemann zeta function ζ(α) on the critical strip. The convergence of η(α) is studied. In particular, its half-plane of convergence gives the possibility to better understand the ζ(α) and its critical strip. As an application, two signal processing networks, corresponding to η(α) and to its Fourier transform respectively, are shortly described.
5
Transient states in quadripoles utilizing fractional order elements
EN
The paper presents a mirror Γ-network containing fractional-order elements. Fractional calculus was employed for the transient analysis of network operation. Comparative analysis was performed for a classic two-port network and defined mirror Γ-network in no-load state, short-circuit state and under load conditions for unit step function input. The obtained results are presented in graphical form and compared to results obtained using classic methods.
PL
W pracy przedstawiono kątowy czwórnik typu Γ zawierający elementy ułamkowego rzędu. Do analizy takiego czwórnika w stanie nieustalonym zastosowano rachunek różniczkowy ułamkowego rzędu. Przeprowadzono analizę porównawczą dla czwórnika klasycznego i omawianego czwórnika dla stanu jałowego i zwarcia dla wymuszenia skokiem jednostkowym. Uzyskane wyniki przedstawiono na wykresach, w porównaniu z wynikami dla czwórnika klasycznego.
6
EN
The paper deals with the model of variable-order nonlinear hereditary oscillator based on a numerical finite-difference scheme. Numerical experiments have been carried out to evaluate the stability and convergence of the difference scheme. It is argued that the approximation, stability and convergence are of the first order, while the scheme is stable and converges to the exact solution
EN
A theory of thermal stresses based on the time-fractional heat conduction equation is considered. The Caputo fractional derivative is used. The fundamental solution to the axisymmetric heat conduction equation in a half-space under the Dirichlet boundary condition and the associated thermal stresses are investigated.
PL
W pracy wykorzystano łuskę gryki do procesu sorpcji jonów metali ciężkich Cu(II), Ni(II), Zn(II), Co(II) i Cd(II) z roztworów wodnych. Wyznaczone zostały maksymalne pojemności sorpcyjne oraz stałe kinetyczne i równowagowe. Obliczone wartości pozwoliły na zastosowanie równań różniczkowych ułamkowych do opisu kinetyki sorpcji oraz uzyskania uogólnionego równania kinetyki sorpcji. Opracowanie wyników według tej koncepcji wymaga napisania procedury obliczeniowej wykorzystującej funkcje gamma oraz szeregi nieskończone. Równania kinetyki z wykorzystaniem pochodnych ułamkowych są równaniami o dwóch parametrach. Są to ułamek pochodnej i stała kinetyczna zależne od analizowanego układu sorbent - adsorbat.
EN
Buckwheat husk for sorption of heavy metal ions Cu(II), Ni(II), Zn(II), Co(II) and Cd(II) from aqueous solutions was presented in the paper. The maximum sorption capacity and kinetics and equilibrium constants were determined. Calculated values were used to describe sorption kinetics by means of fractional derivatives. The calculations were carried out using gamma functions and the infinite series. Two parameters equation was obtained. These parameters are a fraction of a derivative and a kinetics constant depend on the analyzed system.
EN
It was examined if buckwheat hull has a potential to be used to adsorb heavy metal ions Zn(II), Cd(II), Co(II), Cu(II), Ni(II) from water. The research involved experiments aimed at the determination of sorption kinetics taking into consideration changes of concentration in a solution and sorbent over time. According to the literature data, kinetics is described with the use of pseudo first-order equations. Application of fractional derivatives for the description of sorption kinetics enables the development of the generalised sorption kinetics equation. Result analysis with this concept requires making a computational procedure using gamma functions and infinite series. Kinetics description using fractional derivatives will be equations with two parameters ie fraction of derivative α and the kinetics constant K dependent on the analysed sorbent-adsorbate system.
PL
W pracy wykorzystano łuskę gryki do procesu sorpcji jonów metali ciężkich Cu(II), Ni(II), Zn(II), Co(II) i Cd(II) z roztworów wodnych. Wyznaczone zostały maksymalne pojemności sorpcyjne oraz stałe kinetyczne i równowagowe. Obliczone wartości pozwoliły na zastosowanie równań różniczkowych ułamkowych do opisu kinetyki sorpcji oraz uzyskania uogólnionego równania kinetyki sorpcji. Opracowanie wyników według tej koncepcji wymaga napisania procedury obliczeniowej wykorzystującej funkcje gamma oraz szeregi nieskończone. Równania kinetyki z wykorzystaniem pochodnych ułamkowych są równaniami o dwóch parametrach. Są to ułamek pochodnej i stała kinetyczna zależne od analizowanego układu sorbent - adsorbat.
EN
The procedure of the formulation of constitutive equations for asphalt-aggregate mixes is based very often on rheological schemes composed of classical elastic, plastic and viscous elements. The parameters of these schemes can be obtained based on laboratory experiments. In order to obtain better curve fitting results one can use non-classical viscoelastic elements described by fractional derivatives. In this paper we present the characteristics of the fractional viscoelastic Huet-Sayegh model as well as the characteristics of an original simplified fractional model. The results have been obtained using algorithms of numerical calculation of inverse Laplace transforms. Then the proposal of an original rheological model including plasticity has been given. The non-linear differential constitutive relationships of such a model are presented in the paper. The results of computer simulations are also visualized. Finally, 3D viscoelasticplastic models of asphalt aggregatemixes are proposed. The models are based on a generalized macroscopic theory taking into account the effect of pressure-dependency on yielding.
11
Reflection symmetry properties of generalized fractional derivatives
EN
In this paper we study the properties of generalized fractional derivatives (GFDs) with respect to the reflection mapping in finite intervals. We introduce symmetric and antisymmetric derivatives in a given interval and a split of arbitrary function into [J]- projections - parts with well-defined reflection symmetry properties. The main result are representation formulas for the symmetric and anti-symmetric GFDs of order α ∈ (0,1) which allow us to reduce the operators defined in the interval [a,b] to the ones given in arbitrarily short subintervals.
EN
Asphalt-aggregate mixtures constitute basic component for the road pavements construction. The fundamental problem in the procedure of pavement design is to elaborate an appropriate constitutive model suited for the structural behaviour modelling within a wide range of mechanical and environmental loadings. The paper deals with the identification problem for a model representing constitutive properties of asphalt-aggregate mixtures. The constants characterising such a model should be evaluated based on expe-riments. There were analysed two viscoelastic rheological schemes. The classical Burgers model (Fig. 3a) contains linear elastic and viscous elements, while the Huet-Sayegh model (Fig. 3b) is composed of non-classical viscoelastic elements and its constitutive properties can be described using fractional derivatives. The results of cyclic tests of an asphalt-aggregate mixture were taken from the literature [8]. The experiments were carried out when assuming one-dimensional state of stress within the range of frequencies between 0.5 Hz and 35 Hz. The curve fitting procedure for both models was executed based on its complex moduli evaluation (Eqs. 11a and 11b). The obtained results show that by applying the fractional Huet-Sayegh model one can better fit the experiment in comparison with the classical Burgers model (see Figs. 4 and 5). Further investigations should be focused on description of non-linear effects using fractional and plastic elements. The plasticity phenomenon is important within the range of large intensities of loadings. The work on this area is currently underway by the authors.
EN
The procedure of the formulation of constitutive equations for asphalt-aggregate mixtures is based very often on linear rheological schemes composed of classical elastic and viscous elements. The parameters of these schemes can be obtained based on laboratory experiments. It was proved in the literature that it is possible to obtain better curve fitting results using non-classical viscoelastic elements described by fractional derivatives. In this paper we will present the characteristics of the fractional Huet-Sayegh model. The problem of estimation of its parameters was analyzed in our previous paper [2]. We will show the results of calculations in the form of creep and relaxation curves as well as hysteretic loops. The characteristics of the fractal model will be compared with the characteristics of the classical viscoelastic Burgers model. The results were obtained using algorithms of numerical calculation of inverse Laplace transforms.
PL
W procedurze formułowania relacji konstytutywnych mieszanek mineralno-asfaltowych (MMA) są wykorzystywane najczęściej liniowe struktury reologiczne zawierające klasyczne elementy sprężyste i lepkie. Wartości parametrów takich struktur wyznacza się na podstawie wyników badań doświadczalnych. W wielu pracach wykazano, iż zastosowanie nieklasycznych elementów lepkosprężystych, opisywanych za pomocą pochodnej ułamkowego rzędu (pochodnej fraktalnej), umożliwia lepsze dopasowanie wyników badań. W niniejszym opracowaniu zajmujemy się charakterystykami fraktalnego modelu Hueta-Sayegha. Zagadnienie estymacji jego parametrów przedstawiliśmy we wcześniejszej pracy [2]. Podamy wyniki obliczeń w postaci krzywych pełzania, relaksacji i pętli histerezy. Charakterystyki modelu fraktalnego zostaną przedstawione na tle charakterystyk klasycznego, lepkosprężystego modelu Burgersa. Rozwiązania uzyskano przy zastosowaniu algorytmów numerycznego wyznaczania odwrotnych transformat Laplace'a.
14
Properties of resonance-type and dynamic vibration eliminators
EN
The paper presents a rheological model of a body, which properties are described by means of a fractional derivative of its deformation. Such a model of a body was used to describe the coupling between a protected object and vibration eliminator. Then differential equations of motion were solved and effectiveness of vibration elimination was determined.
PL
W pracy przedstawiono model reologiczny ciała, którego własności opisano niecałkowitą pochodną jego deformacji. Taki model ciała wykorzystano w opisie sprzężenia obiektu chronionego z eliminatorem drgań. Rozwiązano różniczkowe równania ruchu i określono skuteczność eliminacji drgań mechanicznych.
EN
Aim of this work is to extend the results of Clément, Da Prato and Prüss [5] on the fractional white noise perturbation with Hurst parameter H ∈ (0,1). We will obtain similar results and it will turn out that the regularity of the solution u(t) increases with Hurst parameter H.
EN
The paper is concerned with the development and application of differential equations of non-integral order α. Fractional calculus is being used to modeling of fractional-order systems and their constitutive equations for applications mainly to systems with 0 < α < 1, and the methods for their solution. The attraction in using a constitutive description based on fractional calculus for modelling devices produced in cutting-edge technologies and electrocrystallization processes is their potentially superior accuracy, and the possibility of correlating the hierarchical structure of modern circuit elements to the fractional order α. Among various possible criteria by means of which responses of fractional order systems are analyzed and classified is based on using the Laplace transformation and transferring detailed considerations on complex w-plane being connected with s-plane by fractional power maping. A detailed analysis is carried out, and useful design insights are provided. Two illustrative examples are given to show the effectiveness of the proposed analysis method of fractional-order systems.
PL