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Wyświetlanie 1-15 z 46
Tytuł:
Variable thermal conductivity in micropolar thermoelastic medium without energy dissipation possessing cubic symmetry
Autorzy:
Ailawalia, Praveen
Priyanka
Powiązania:
https://bibliotekanauki.pl/articles/27312393.pdf
Data publikacji:
2023
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
transfer ciepła
mikrorotacja
temperatura
variable thermal conductivity
microrotation
temperature distribution
normal mode analysis
Opis:
This investigation deals with the effect of variable thermal conductivity in a micropolar thermoelastic medium without energy dissipation with cubic symmetry. The normal mode technique is employed for obtaining components of physical quantities such as displacement, stress, temperature distribution and microrotation.
Źródło:
International Journal of Applied Mechanics and Engineering; 2023, 28, 1; 1--10
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of variable viscosity on MHD inclined arterial blood flow with chemical reaction
Autorzy:
Tripathi, B.
Sharma, B. K.
Powiązania:
https://bibliotekanauki.pl/articles/264659.pdf
Data publikacji:
2018
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
magnetohydrodynamika
lepkość
reakcja chemiczna
magnetohydrodynamical fluid
homotopy perturbation method
variable viscosity
chemical reaction
Opis:
In this paper, we present the mathematical study of heat and mass transfer effects on an arterial blood flow under the influence of an applied magnetic field with chemical reaction. A case of mild stenosis is considered in a non-tapered artery which is inclined at an angle γ from the axis. The variable viscosity of the blood is considered varying with the hematocrit ratio. Governing non-linear differential equations have been solved by using an analytical scheme, homotopy perturbation method to obtain the solution for the velocity, temperature and concentration profiles of the blood flow. For having an adequate insight to blood flow behavior through a stenosed artery, graphs have been plotted for wall shear stress, velocity, temperature and concentration profiles with varying values of the applied magnetic field, chemical reaction parameter and porosity parameter. The results show that in an inclined artery, the magnitude of the wall shear stress at stenosis throat increases as values of the applied magnetic field increase while it reduces as the values of both the chemical reaction and porosity parameters increase. Contour plots have been plotted to show the variations of the velocity profile of blood flow as the values of the height of the stenosis as well as the influence of the applied magnetic field increase.
Źródło:
International Journal of Applied Mechanics and Engineering; 2018, 23, 3; 767-785
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Variable structure observer design for a class of uncertain systems with a time-varying delay
Autorzy:
Liu W., J.
Powiązania:
https://bibliotekanauki.pl/articles/330119.pdf
Data publikacji:
2012
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
obserwator
niezmienniczość
uogólniona odwrotność macierzy
variable structure observer
invariance property
generalized matrix inverse approach
Opis:
Design of a state observer is an important issue in control systems and signal processing. It is well known that it is difficult to obtain the desired properties of state feedback control if some or all of the system states cannot be directly measured. Moreover, the existence of a lumped perturbation and/or a time delay usually reduces the system performance or even produces an instability in the closed-loop system. Therefore, in this paper, a new Variable Structure Observer (VSO) is proposed for a class of uncertain systems subjected to a time varying delay and a lumped perturbation. Based on the strictly positive real concept, the stability of the equivalent error system is verified. Based on the generalized matrix inverse approach, the global reaching condition of the sliding mode of the error system is guaranteed. Also, the proposed variable structure observer will be shown to possess the invariance property in relation to the lumped perturbation, as the traditional variable structure controller does. Furthermore, two illustrative examples with a series of computer simulation studies are given to demonstrate the effectiveness of the proposed design method.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2012, 22, 3; 575-583
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Variable gravity effects on thermal instability of nanofluid in anisotropic porous medium
Autorzy:
Chand, R.
Rana, G. C.
Kumar, S.
Powiązania:
https://bibliotekanauki.pl/articles/265426.pdf
Data publikacji:
2013
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
porowatość
liczba Rayleigha
zmienna grawitacja
nanofluid
anisotropic porous medium
Rayleigh number
variable gravity
Opis:
In this paper, we study the effects of variable gravity on thermal instability in a horizontal layer of a nanofluid in an anisotropic porous medium. Darcy model been used for the porous medium. Also, it incorporates the effect of Brownian motion along with thermophoresis. The normal mode technique is used to find the confinement between two free boundaries. The expression of the Rayleigh number has been derived, and the effects of variable gravity and anisotropic parameters on the Rayleigh number have been presented graphically.
Źródło:
International Journal of Applied Mechanics and Engineering; 2013, 18, 3; 631-642
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Time-optimal control of linear fractional systems with variable coefficients
Autorzy:
Matychyn, Ivan
Onyshchenko, Viktoriia
Powiązania:
https://bibliotekanauki.pl/articles/2055161.pdf
Data publikacji:
2021
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
fractional calculus
Riemann-Liouville derivative
variable coefficients
optimal control
rachunek ułamkowy
pochodna ułamkowa Riemanna-Liouville'a
współczynnik zmienny
sterowanie optymalne
Opis:
Linear systems described by fractional differential equations (FDEs) with variable coefficients involving Riemann–Liouville and Caputo derivatives are examined in the paper. For these systems, a solution of the initial-value problem is derived in terms of the generalized Peano–Baker series and a time-optimal control problem is formulated. The optimal control problem is treated from the convex-analytical viewpoint. Necessary and sufficient conditions for time-optimal control similar to that of Pontryagin’s maximum principle are obtained. Theoretical results are supported by examples.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2021, 31, 3; 375--386
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electrically conducting flow through exponential power law fluid with variable thermal conductivity
Autorzy:
Ferdows, M.
Bangalee, M. Z. I.
Liu, D.
Powiązania:
https://bibliotekanauki.pl/articles/265439.pdf
Data publikacji:
2019
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
magnetohydrodynamika
warstwa graniczna
podobieństwa
MHD
similarity solution
variable properties
boundary layer flow
exponential law
Opis:
The problem of exponential law of steady, incompressible fluid flow in boundary layer and heat transfer are studied in an electrically conducting fluid over a semi-infinite vertical plate assuming the variable thermal conductivity in the presence of a uniform magnetic field. The governing system of equations including the continuity equation, momentum equation and energy equation have been transformed into nonlinear coupled ordinary differential equations using appropriate similarity variables. All the numerical and graphical solutions are obtained through the use of Maple software. The solutions are found to be dependent on three dimensionless parameters including the magnetic field parameter M, thermal conductivity parameter and Prandtl number Pr. Representative velocity and temperature profiles are presented at various values of the governing parameters. The skin-friction coefficient and the rate of heat transfer are also calculated for different values of the parameters.
Źródło:
International Journal of Applied Mechanics and Engineering; 2019, 24, 3; 539-548
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A variable structure observer for the control of robot manipulators
Autorzy:
Abdessameud, A.
Khelfi, M. F.
Powiązania:
https://bibliotekanauki.pl/articles/908406.pdf
Data publikacji:
2006
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
obserwator
manipulator robotyczny
stateczność wykładnicza
system naprowadzający
variable structure observers
switching-type observers
rigid robot manipulators
exponential stability
tracking control
Opis:
This paper deals with the application of a variable structure observer developed for a class of nonlinear systems to solve the trajectory tracking problem for rigid robot manipulators. The analyzed approach to observer design proposes a simple design methodology for systems having completely observable linear parts and bounded nonlinearities and/or uncertainties. This observer is basically the conventional Luenberger observer with an additional switching term that is used to guarantee robustness against modeling errors and system uncertainties. To solve the tracking problem, we use a control law developed for robot manipulators in the full information case. The closed loop system is shown to be globally asymptotically stable based on Lyapunov arguments. Simulation results on a 3-DOF robot manipulator show the asymptotic convergence of the vectors of observation and tracking errors.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2006, 16, 2; 189-196
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Random perturbation of the variable metric method for unconstrained nonsmooth nonconvex optimization
Autorzy:
El Mouatasim, A.
Ellaia, R.
Souza de Cursi, J. E.
Powiązania:
https://bibliotekanauki.pl/articles/908374.pdf
Data publikacji:
2006
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
optymalizacja
zaburzenie stochastyczne
zaburzenie losowe
nonconvex optimization
stochastic perturbation
variable metric method
nonsmooth optimization
generalized gradient
Opis:
We consider the global optimization of a nonsmooth (nondifferentiable) nonconvex real function. We introduce a variable metric descent method adapted to nonsmooth situations, which is modified by the incorporation of suitable random perturbations. Convergence to a global minimum is established and a simple method for the generation of suitable perturbations is introduced. An algorithm is proposed and numerical results are presented, showing that the method is computationally effective and stable.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2006, 16, 4; 463-474
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Heat and mass transfer effect on an infinite vertical plate in the presence of hall current and thermal radiation with variable temperature
Autorzy:
Manjula, L.
Muthucumaraswamy, R.
Powiązania:
https://bibliotekanauki.pl/articles/2106450.pdf
Data publikacji:
2021
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
magnetohydrodynamika
efekt Halla
promieniowanie
MHD
Hall effect
radiation
vertical plate
variable temperature
Opis:
MHD and radiated heat flow on a rotating system of an electrically conducting fluid in the presence of Hall current under the influence of variable temperature is studied analytically. An exact solution of a non-dimensional form of coupled partial differential equations is obtained by the technique of Laplace transform. The effect of temperature, velocity and concentration is analyzed for various parameters like the Hall parameter [...], thermal radiation [...], rotation parameter [...], Hartmann number [...] and results are discussed in detail with the help of graphs. A mixed analysis of a rotating fluid with Hall current and thermal radiation plays a very essential role in the research area such as plasma physics, MHD generator, fluid drift sensor, cosmological and geophysical level, etc.
Źródło:
International Journal of Applied Mechanics and Engineering; 2021, 26, 3; 131--140
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Triple diffusive convection of a non-Newtonian fluid under the combined effect of compressibility and variable gravity
Autorzy:
Aggarwal, A. K.
Dixit, D.
Powiązania:
https://bibliotekanauki.pl/articles/265482.pdf
Data publikacji:
2019
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
dyfuzja
płyn Rivlina-Ericksena
ściśliwość
zmienna grawitacja
triple diffusion
Rivlin-Ericksen fluid
suspended particles
porous medium
compressibility
variable gravity
Opis:
In this paper, triple diffusive convection in a Rivlin-Ericksen fluid layer, which is permeated with suspended particles in the porous medium under the effect of compressibility and variable gravity, is investigated. Linear stability theory and normal mode analysis have been used to study the problem under consideration. It is observed that, for stationary convection, suspended particles, compressibility and medium permeability have destabilizing/stabilizing effects under certain conditions. The variable gravity parameter destabilizes the system whereas stable solute gradients have a stabilizing effect.
Źródło:
International Journal of Applied Mechanics and Engineering; 2019, 24, 4; 1-11
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Finite difference solution of unsteady flow past an oscillating semi-infinite vertical plate with variable surface temperature and uniform mass flux
Autorzy:
Muthucumaraswamy, R.
Saravanan, B.
Powiązania:
https://bibliotekanauki.pl/articles/955236.pdf
Data publikacji:
2014
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
promieniowanie
płyta pionowa
strumień masy
radiation
vertical plate
finite differences
variable temperature
uniform mass flux
Opis:
A finite difference solution of an unsteady flow past an oscillating semi-infinite vertical place with variable temperature and uniform mass flux is presented here. The fluid considered here is a gray, absorbing-emitting radiation but a non-scattering medium. The dimensionless governing equations are solved by an efficient, more accurate, and unconditionally stable and fast converging implicit scheme. The steady state velocity, temperature and concentration profiles are shown graphically. The effect of velocity and temperature for different physical parameters such as the thermal radiation, Schmidt number, thermal Grashof number and mass Grashof number is studied. It is observed that the velocity decreases in the presence of thermal radiation. It is also observed that the time taken to reach a steady-state is more in the case of vertical plate than horizontal plate.
Źródło:
International Journal of Applied Mechanics and Engineering; 2014, 19, 4; 709-724
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Random perturbation of the projected variable metric method for nonsmooth nonconvex optimization problems with linear constraints
Autorzy:
El Mouatasim, A.
Ellaia, R.
Souza de Cursi, E.
Powiązania:
https://bibliotekanauki.pl/articles/907785.pdf
Data publikacji:
2011
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
optymalizacja globalna
ograniczenie liniowe
zaburzenie stochastyczne
global optimization
linear constraints
variable metric method
stochastic perturbation
nonsmooth optimization
Opis:
We present a random perturbation of the projected variable metric method for solving linearly constrained nonsmooth (i.e., nondifferentiable) nonconvex optimization problems, and we establish the convergence to a global minimum for a locally Lipschitz continuous objective function which may be nondifferentiable on a countable set of points. Numerical results show the effectiveness of the proposed approach.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2011, 21, 2; 317-329
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On diffusion of chemically reactive species in a convective flow past an inclined plate with variable surface temperature and variable mass diffusion
Autorzy:
Kirubavathi, J. D.
Palani, G.
Powiązania:
https://bibliotekanauki.pl/articles/266086.pdf
Data publikacji:
2016
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
metoda różnic skończonych
płyta pochylona
tarcie
chemically reactive species
Nusselt number
skin friction
finite-difference methods
inclined plate
Opis:
A numerical solution of a transient natural convection flow past a semi-infinite inclined plate under the combined buoyancy effects of heat and mass transfer along with chemical reaction is presented herewith. The governing boundary layer equations for the above flow problem for a first order homogeneous chemical reaction are set up and non-dimensionalised. An implicit finite difference method is employed to solve the unsteady, nonlinear, integro and coupled partial differential equation. Numerical results are presented for various parameters occurring in the problem. The unsteady velocity, temperature and concentration profiles, local and average skin friction, Nusselt number and Sherwood number are studied for both a generative and destructive reaction.
Źródło:
International Journal of Applied Mechanics and Engineering; 2016, 21, 4; 905-922
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Simultaneous effects of heat transfer and variable viscosity on peristaltic transport of casson fluid flow in an inclined porous tube
Autorzy:
Manjunatha, G.
Rajashekhar, C.
Vaidya, H.
Prasad, K. V.
Powiązania:
https://bibliotekanauki.pl/articles/266265.pdf
Data publikacji:
2019
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
liczba Darcy'ego
zmienna lepkość
granica plastyczności
Darcy number
thermal slip
velocity slip
variable viscosity
yield stress
Opis:
The present study investigates the combined effects of varying viscosity and heat transfer on a Casson fluid through an inclined porous axisymmetric tube in the presence of slip effects. The modeled governing equations are solved analytically by considering the long wavelength and small Reynolds number approximations. The numerical integration is employed to obtain pressure rise and frictional force. A parametric analysis has been presented to study the effects of the Darcy number, angle of inclination, varying viscosity, velocity slip, thermal slip, yield stress, amplitude ratio, Prandtl number and Eckert number on the pressure rise, pressure gradient, streamlines, frictional force and temperature. The study reveals that an increase in the angle of inclination and viscosity parameter has a proportional increase in the pressure rise. Also, an increase in the porosity causes a significant reduction in the pressure rise.
Źródło:
International Journal of Applied Mechanics and Engineering; 2019, 24, 2; 309-328
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Time-Domain Synthesis of Linear Circuits With Periodically Variable Parameters
Autorzy:
Siwczyński, M.
Powiązania:
https://bibliotekanauki.pl/articles/911223.pdf
Data publikacji:
2000
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
układ parametryczny
synteza
optymalizacja
parametric circuits
synthesis
optimisation
Opis:
A novel synthesis method of linear electric networks with periodically variable parameters is presented. These types of networks can be implemented as resistance-parametric, (conductance-capacitance)-parametric or (resistance- inductance)- parametric multiports. The time-varying parameters are determined so as to extremize some specific optimisation criteria. Consequently, the synthesis task has a unique solution. The starting point of the solution method is the original theorem proved in the paper, which deals with the minimum-energy networks.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2000, 10, 3; 623-637
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 46

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