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EN
In this paper, an exact analytical solution for the motion of fractionalized second grade fluid flows moving over accelerating plate under the influence of slip has been obtained. A coupled system of partial differential equations representing the equation of motion has been re-written in terms of fractional derivatives form by using the Caputo fractional operator. The Discrete Laplace transform method has been employed for computing the expressions for the velocity field […] and the corresponding shear stress […]. The obtained solutions for the velocity field and the shear stress have been written in terms of Wright generalized hypergeometric function pqψ and are expressed as a sum of the slip contribution and the corresponding no-slip contribution. In addition, the solutions for a fractionalized, ordinary second grade fluid and Newtonian fluid in the absence of slip effect have also been obtained as special case. Finally, the effect of different physical parameters has been demonstrated through graphical illustrations.
2
Content available A study on fractional order thermoelastic half space
EN
In this paper, we consider a one dimensional problem on a fractional order generalized thermoelasticity in half space subjected to an instantaneous heat source. The Laplace transform as well as eigen value approach techniques are applied to solve the governing equations of motion and heat conduction. Closed form solutions for displacement, temperature and stress are obtained and presented graphically.
EN
In the present research analysis, linear fractional order ordinary differential equations with some defined condition (s) have been solved under the Caputo differential operator having order α > 0 via the Shehu integral transform technique. In this regard, we have presented the proof of finding the Shehu transform for a classical nth order integral of a piecewise continuous with an exponential nt h order function which leads towards devising a theorem to yield exact analytical solutions of the problems under investigation. Varying fractional types of problems are solved whose exact solutions can be compared with solutions obtained through existing transformation techniques including Laplace and Natural transforms.
EN
A three-phase-lag (TPL) model is proposed to describe heat transfer in a finite domain skin tissue with temperature dependent metabolic heat generation. The Laplace transform method is applied to solve the problem. Three special types of heat flux are applied to the boundary of skin tissue for thermal therapeutic applications. The depth of tissue is influenced by the different oscillation heat flux. The comparison between the TPL and dual-phase-lag (DPL) models is analyzed and the effects of phase lag parameters […] and material constant […] on the tissue temperature distribution are presented graphically.
EN
A two-dimensional Cauchy Poisson problem for water with a porous bottom generated by an axisymmetric initial surface disturbance is investigated here. The problem is formulated as an initial value problem for the velocity potential describing the motion in the fluid. The Laplace and Hankel transform techniques have been used in the mathematical analysis to obtain the form of the free surface in terms of a multiple infinite integral. This integral is then evaluated asymptotically by the method of stationary phase. The asymptotic form of the free surface is depicted graphically in a number of figures for different values of the porosity parameter and for different types of initial disturbances.
EN
In the present work, we consider a two dimensional axisymmetric problem of micropolar porous circular plate with thermal and chemical potential sources in the context of the theory of dual phase lag generalized thermoelastic diffusion. The potential functions are used to analyze the problem. The Laplace and Hankel transforms techniques are used to find the expressions of displacements, microrotation, volume fraction field, temperature distribution, concentration and stresses in the transformed domain. The inversion of transforms based on Fourier expansion techniques is applied to obtain the results in the physical domain. The numerical results for resulting quantities are obtained and depicted graphically. Effect of porosity, LS theory and phase lag are presented on the resulting quantities. Some particular cases are also deduced.
EN
Recently the authors obtained several Laplace transforms of convolution type integrals involving Kummer’s function 1F1 [Appl. Anal. Discrete Math., 2018, 12(1), 257–272]. In this paper, the authors aim at presenting several new and interesting Laplace transforms of convolution type integrals involving product of two special generalized hypergeometric functions pFp by employing classical summation theorems for the series 2F1, 3F2, 4F3 and 5F4 available in the literature.
EN
The time-fractional heat conduction equation with heat absorption proportional to temperature is considered in the case of central symmetry. The fundamental solutions to the Cauchy problem and to the source problem are obtained using the integral transform technique. The numerical results are presented graphically.
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
The present investigation is concerned with a two dimensional axisymmetric problem in a homogeneous isotropic micropolar porous thermoelastic circular plate by using the eigen value approach. The Laplace and Hankel transform are used to solve the problem. The expression of displacements, microrotation, volume fraction field, temperature distribution and stresses are obtained in the transformed domain subjected to thermomechanical sources. A computer algorithm is developed for numerical computations. To obtain the resulting quantities in a physical domain, a numerical inversion technique is used. The resulting quantities are depicted graphically for a specific model. Some special cases are also deduced.
11
Content available K-dron, jego matematyczne modelowanie i zastosowanie
PL
W pracy przedstawiono pojęcie K-dronu, nowego kształtu geometrycznego odkrytego w 1985 roku w Nowym Jorku przez dr. Janusza Kapustę, historię jego odkrycia, związki z geometrią, symetrią sześcianu. Należy podkreślić, że autorzy wyprowadzili nowy wzór na powierzchnie K-dronu, stosując metodę transformacji Laplace’a do wyznaczenia rozwiązania zagadnienia brzegowo-początkowego do równania drgań struny. Wyprowadzony wzór w swojej naturze jest bardziej czytelny ze wzlgędu na swoją strukturę. Otrzymane przez autorów w pracy rozwiązanie opisuje w sposób najbardziej ogólny powierzchnie K-dronu oraz bardziej ogólne powierzchnie nazwane przez autorów n-K-dronem. Wzór na powierzchnie K-dronu uzyskany metodą transformaty Laplace’a posiada przejrzystą interpretację geometryczną, ponieważ jest przedstawiony w postaci kombinacji liniowej równań płaszczyzn o współczynnikach kierunkowych określonych przez odpowiednie kombinacje funkcje Heaviside’a. Szeroko także przedstawiono różnorodne i wielorakie zastosowanie K-dronu.
EN
In this paper we present the definition of K-dron, new geometrical form discovered by Janusz Kapusta in 1985 in New York, its history and connection between geometry and symmetry of a cube. It is worth to emphasize that the authors have derived new formulae for the surface of K-dron using the Laplacea transform in order to obtain the solution of the boundary-value problem for the partial differential equation describing the vibration of the string. The formula proved by us in this paper is clearer and understandable in view of this structure. The solution obtained in this paper describes in general manner the surface of K-dron and more general surfaces named by us n-K-drons. The formula for the surface of K-dron was derived by the method of Laplacea transform having clear geometrical and physical interpretation because it is presented in linear combination of the equation of planes with the coefficients of directions described by suitable combinations of Heavisides functions. Also wide range and different applications of K-dron are presented.
EN
An exact solution of an unsteady flow past a parabolic starting motion of an infinite vertical plate with variable temperature and mass diffusion, in the presence of a homogeneous chemical reaction of first order has been studied. The plate temperature as well as concentration level near the plate are raised linearly with time t. The dimensionless governing equations are solved using the Laplace-transform technique. The effects of velocity profiles are studied for different physical parameters such as the chemical reaction parameter, thermal Grashof number, mass Grashof number, Schmidt number and time. It is observed that the velocity increases with increasing values of the thermal Grashof number or mass Grashof number. The trend is just reversed with respect to the chemical reaction parameter.
EN
In the following work the authors implement mathematical representation of a control system of complex dynamic system. An example of such system is a group of unmanned aerial vehicles. The sufficiency of controlled object mathematical representation is implemented, using the system approach, which in turn describes system elements, taking into account all the relations between them.
PL
W prezentowanej pracy autorzy wdrażają matematyczny opis systemu kontroli złożonego systemu dynamicznego. Przykładem takiego systemu jest grupa bezzałogowych samolotów. Zaimplementowano odpowiedni opis matematyczny kontrolowanego obiektu stosując podejście systemowe, które opisuje wszystkie elementy systemu uwzględniając wszystkie relacje między nimi.
EN
The second axisymmetric problem in a micropolar elastic medium has been investigated by employing an eigen value approach after applying the Laplace and the Hankel transforms. An example of infinite space with concentrated force at the origin has been presented to illustrate the application of the approach. The integral transforms have been inversed by using a numerical technique to obtain the components of microrotation, displacement, force stress and couple stress in the physical domain. The results for these quantities are given and illustratred graphically.
EN
The eigen value approach, following the Laplace and Hankel transformation has been employed to find a general solution of the field equations in a micropolar elastic medium with voids for an axisymmetric problem. An infinite space with the mechanical source has been applied to illustrate the utility of the approach. The integral transformations has been inverted by using a numerical inversion technique to get the result in physical domain. The results in the form of normal displacement, volume fraction, normal force stress, tangential force stress and tangential couple stress components have been obtained numerically and illustrated graphically.
16
Content available remote Laplace transforms of the logarithmic functions and their applications
EN
This paper deals with theorems and formulas using the technique of Laplace and Steiltjes transforms expressed in terms of interesting alternative logarithmic and related integral representations. The advantage of the proposed technique is illustrated by logarithms of integrals of importance in certain physical and statistical problems.
EN
Thermal radiation effects on an unsteady flow of a viscous incompressible and electrically conducting fluid past an impulsively started infinite vertical plate in the presence of i) variable temperature, ii) uniform mass diffusion and iii) a uniform magnetic field applied transversely to the flow, are studied. The dimensionless governing equations are solved by using the Laplace transform technique. The velocity, concentration as well as temperature distributions and skin-friction are studied for different values of the parameters involved. Results obtained are presented with the help of graphs and tables.
18
EN
An exact solution to the problem of an unsteady two dimensional free convection flow past an infinite vertical porous plate, which moves with a constant velocity in a viscous and incompressible fluid in the presence of thermal radiation is presented. The Laplace transform technique is used. The fluid is a gray fluid, absorbing-emitting radiation but a non scattering medium.
EN
Solutions to time-fractional diffusion-wave equation with a source term in spherical coordinates are obtained for an infinite medium. The solutions are found using the Laplace transform with respect to time t, the finite Fourier transform with respect to the angular coordinate , the Legendre transform with respect to the spatial coordinate , and the Hankel transform of the order n+1/2 with respect to the radial coordinate . In the central symmetric case with one spatial coordinate the obtained results coincide with those studied earlier.
EN
We discuss a processor sharing system with non-homogeneous customers. There are resources of two types for their service: 1) resource of the first type is discrete, there are N units (servers) of the resource; 2) resource of the second type (capacity) is not-necessary discrete. The type of a customer is defined by the amount of first type resource units which is used for the customer service. Each customer is also characterized by some random capacity or some amount of the second type resource which is also used for his service. The total capacity of customers present in the system is limited by some value V >0, which is called the memory volume of the system. The customer capacity and length (the work necessary for service) are generally dependent. The joint distribution of these random variables also depends on the customer type. For such systems we determine the stationary distribution of the number of customers of each type present in the system and stationary loss probabilities for each type of customers.
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