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    Wyświetlanie 1-12 z 12
    Tytuł:
    The influence of thermal expansion on flow past an inclined accelerated sectional plate with persistent mass diffusion
    Autorzy:
    Nagarajan, G.
    Sundar Raj, M.
    Muthucumaraswamy, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/27312397.pdf
    Data publikacji:
    2022
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    rozszerzalność cieplna
    dyfuzja masy
    transformata Laplace'a
    thermal expansion
    mass diffusion
    accelerated
    inclined plate
    isothermal
    Opis:
    In this article, we examined the solution of a homogeneously intensified isothermal inclined infinite plate with constant temperature. The plate is elevated to Tw, and the species accumulation is enhanced at a consistent speed. Under appropriate boundary conditions, the non-dimensional guiding formulae are remedied using the Laplace transform procedure. The effect of velocity, temperature, and concentration on various factors, including thermal and mass Grashof numbers, Schmidt numbers, and duration, is discussed. The velocity increases proportionally to the thermal and mass Grashof numbers, but decreases as the inclined angle, Schmidt numbers and time increase.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2022, 27, 4; 105--116
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Experimental regulating parameters of bladder-type hydraulic accumulator
    Autorzy:
    Zhuk, Volodymyr
    Verbovskyi, Orest
    Popadiuk, Ihor
    Powiązania:
    https://bibliotekanauki.pl/articles/2174165.pdf
    Data publikacji:
    2022
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    akumulator hydrauliczny
    pojemność magazynowa
    termodynamika
    discharge cycle
    hydraulic accumulator
    non-stationary expansion
    polytropic index
    storage volume
    Opis:
    Experimental regulating parameters of the non-stationary expansion of air inside a bladder-type hydraulic accumulator, working with the simple short pipeline, are presented in the paper. The technique of continuous online monitoring of changes in time of volume and absolute air pressure inside the hydraulic accumulator during the discharge process has been improved. Three series of experimental studies of transient gas processes inside the accumulator at different values of the average volume flow rate are made. Tendencies of change of the integral parameters of the hydraulic accumulator are obtained and analyzed depending on the serial number of the discharge cycle. A general dependence of dimensionless storage volume Kreg on the polytropic index n in series # 1–3, approximated by single power-law dependence, is obtained. The systematic changes of integral parameters in each subsequent discharge cycle can be explained by the non-stationary transient thermodynamic processes in air inside the accumulator until the thermodynamic equilibrium with the ambient air parameters is reached.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2022, 27, 1; 232--243
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Edge waves over a shelf
    Autorzy:
    Dolai, P.
    Dolai, D. P.
    Powiązania:
    https://bibliotekanauki.pl/articles/264611.pdf
    Data publikacji:
    2019
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    fala brzegowa
    wielomian Gegenbauera
    relacja dyspersji
    shelf
    edge wave
    Havelock expansion
    Galerkin approximation
    Gegenbauer polynomial
    dispersion relation
    Opis:
    The problem considered in this paper is the derivation of properties of edge waves travelling along a submerged horizontal shelf. The problem is formulated within the framework of the linearized theory of water waves and Havelock expansions of water wave potentials are used in the mathematical analysis to obtain the dispersion relation for edge waves in terms of an integral. Appropriate multi-term Galerkin approximations involving ultra spherical Gegenbauer polynomials are utilized to obtain a very accurate numerical estimate for the integral and hence to derive the properties of edge waves over a shelf. The numerical results are illustrated in a table and curves are presented showing the variation of frequency of the edge waves with the width of the shelf.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2019, 24, 2; 453-460
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Oblique water wave diffraction by a step
    Autorzy:
    Dolai, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/264885.pdf
    Data publikacji:
    2017
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    finite step
    Havelock expansion
    Galerkin approximation
    Gegenbauer polynomial
    reflection and transmission coefficients
    aproksymacja Galerkina
    wielomian Gegenbauera
    odbicie
    Opis:
    This paper is concerned with the problem of diffraction of an obliquely incident surface water wave train on an obstacle in the form of a finite step. Havelock expansions of water wave potentials are used in the mathematical analysis to obtain the physical parameters reflection and transmission coefficients in terms of integrals. Appropriate multi-term Galerkin approximations involving ultraspherical Gegenbauer polynomials are utilized to obtain a very accurate numerical estimate for reflection and transmission coefficients which are depicted graphically. From these figures various interesting results are discussed.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2017, 22, 1; 35-47
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A robust computational technique for a system of singularly perturbed reaction–diffusion equations
    Autorzy:
    Kumar, V.
    Bawa, R. K.
    Lal, A. K.
    Powiązania:
    https://bibliotekanauki.pl/articles/330202.pdf
    Data publikacji:
    2014
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    asymptotic expansion approximation
    backward difference operator
    trapezoidal method
    piecewise uniform Shishkin mesh
    rozwinięcie asymptotyczne
    operator różnicowy
    metoda trapezowa
    Opis:
    In this paper, a singularly perturbed system of reaction–diffusion Boundary Value Problems (BVPs) is examined. To solve such a type of problems, a Modified Initial Value Technique (MIVT) is proposed on an appropriate piecewise uniform Shishkin mesh. The MIVT is shown to be of second order convergent (up to a logarithmic factor). Numerical results are presented which are in agreement with the theoretical results.
    Źródło:
    International Journal of Applied Mathematics and Computer Science; 2014, 24, 2; 387-395
    1641-876X
    2083-8492
    Pojawia się w:
    International Journal of Applied Mathematics and Computer Science
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Finite-Dimensional Control of Nonlinear Parabolic Pde Systems With Time-Dependent Spatial Domains Using Empirical Eigenfunctions
    Autorzy:
    Armaou, A.
    Christofides, P. D.
    Powiązania:
    https://bibliotekanauki.pl/articles/908332.pdf
    Data publikacji:
    2001
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    sterowanie nieliniowe
    sterowanie skończenie wymiarowe
    Karhunen-Loeve expansion
    Galerkin's method
    nonlinear control
    diffusion-reaction processes with moving boundaries
    Opis:
    This article presents a methodology for the synthesis of finite-dimensional nonlinear output feedback controllers for nonlinear parabolic partial differential equation (PDE) systems with time-dependent spatial domains. Initially, the nonlinear parabolic PDE system is expressed with respect to an appropriate time-invariant spatial coordinate, and a representative (with respect to different initial conditions and input perturbations) ensemble of solutions of the resulting time-varying PDE system is constructed by computing and solving a high-order discretization of the PDE. Then, the Karhunen-Loeve expansion is directly applied to the ensemble of solutions to derive a small set of empirical eigenfunctions (dominant spatial patterns) that capture almost all the energy of the ensemble of solutions. The empirical eigenfunctions are subsequently used as basis functions within a Galerkin model reduction framework to derive low-order ordinary differential equation (ODE) systems that accurately describe the dominant dynamics of the PDE system. The ODE systems are subsequently used for the synthesis of nonlinear output feedback controllers using geometric control methods. The proposed control method is used to stabilize an unstable steady-state of a diffusion-reaction process with nonlinearities, spatially-varying coefficients and time-dependent spatial domain, and is shown to lead to the construction of accurate low-order models and the synthesis of low-order controllers. The performance of the low-order models and controllers is successfully tested through computer simulations.
    Źródło:
    International Journal of Applied Mathematics and Computer Science; 2001, 11, 2; 287-317
    1641-876X
    2083-8492
    Pojawia się w:
    International Journal of Applied Mathematics and Computer Science
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Scattering of oblique water waves by an infinite step
    Autorzy:
    Dolai, P.
    Dolai, D. P.
    Powiązania:
    https://bibliotekanauki.pl/articles/265749.pdf
    Data publikacji:
    2018
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    aproksymacja Galerkina
    wielomian Gegenbauera
    współczynnik transmisji
    infinite step
    Havelock expansion
    Galerkin approximation
    Gegenbauer polynomial
    reflection and transmission coefficients
    Opis:
    The present paper is concerned with the problem of scattering of obliquely incident surface water wave train passing over a step bottom between the regions of finite and infinite depth. Havelock expansions of water wave potentials are used in the mathematical analysis to obtain the physical parameters reflection and transmission coefficients in terms of integrals. Appropriate multi-term Galerkin approximations involving ultra spherical Gegenbauer polynomials are utilized to obtain very accurate numerical estimates for reflection and transmission coefficients. The numerical results are illustrated in tables.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2018, 23, 2; 327-338
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Scattering of internal waves by vertical barrier in a channel of stratified fluid
    Autorzy:
    Dolai, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/264794.pdf
    Data publikacji:
    2015
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    stratified fluid
    internal wave
    vertical barrier
    stream function
    scattering matrix
    Boussinesq approximation
    eigen function expansion
    rozwarstwienie
    hydromechanika
    fala wewnętrzna
    Opis:
    The problem of two dimensional internal wave scattering by a vertical barrier in the form of a submerged plate, or a thin wall with a gap in an exponentially stratified fluid of uniform finite depth bounded by a rigid plane at the top, is considered in this paper. Assuming linear theory and the Boussinesq approximation, the problem is formulated in terms of the stream function. In the regions of the two sides of the vertical barrier, the scattered stream function is represented by appropriate eigen function expansions. By the use of appropriate conditions on the barrier and the gap, a dual series relation involving the unknown elements of the scattering matrix is produced. By defining a function with these unknown elements as its Fourier sine expansion series, it is found that this function satisfies a Carleman type integral equation on the barrier whose solution is immediate. The elements of the scattering matrix are then obtained analytically as well as numerically corresponding to any mode of the incident internal wave train for each barrier configuration. A comparison with earlier results available in the literature shows good agreement. To visualize the effect of the barrier on the fluid motion, the stream lines for an incident internal wave train at the lowest mode are plotted.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2015, 20, 3; 471-485
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A memory-efficient noninteger-order discrete–time state–space model of a heat transfer process
    Autorzy:
    Oprzędkiewicz, K.
    Mitkowski, W.
    Powiązania:
    https://bibliotekanauki.pl/articles/331055.pdf
    Data publikacji:
    2018
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    noninteger order system
    heat transfer equation
    infinite dimensional system
    continuous fraction expansion
    układ niecałkowitego rzędu
    wymiana ciepła
    układ nieskończenie wymiarowy
    Opis:
    A new, state space, discrete-time, and memory-efficient model of a one-dimensional heat transfer process is proposed. The model is derived directly from a time-continuous, state-space semigroup one. Its discrete version is obtained via a continuous fraction expansion method applied to the solution of the state equation. Fundamental properties of the proposed model, such as decomposition, stability, accuracy and convergence, are also discussed. Results of experiments show that the model yields good accuracy in the sense of the mean square error, and its size is significantly smaller than that of the model employing the well-known power series expansion approximation.
    Źródło:
    International Journal of Applied Mathematics and Computer Science; 2018, 28, 4; 649-659
    1641-876X
    2083-8492
    Pojawia się w:
    International Journal of Applied Mathematics and Computer Science
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A simple scheme for semi-recursive identification of Hammerstein system nonlinearity by Haar wavelets
    Autorzy:
    Śliwiński, P.
    Hasiewicz, Z.
    Wachel, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/330481.pdf
    Data publikacji:
    2013
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    Hammerstein system
    non parametric recursive identification
    Haar orthogonal expansion
    convergence analysis
    numerical stability
    system Hammersteina
    identyfikacja rekurencyjna nieparametryczna
    analiza zbieżności
    stateczność numeryczna
    Opis:
    A simple semi-recursive routine for nonlinearity recovery in Hammerstein systems is proposed. The identification scheme is based on the Haar wavelet kernel and possesses a simple and compact form. The convergence of the algorithm is established and the asymptotic rate of convergence (independent of the input density smoothness) is shown for piecewise-Lipschitz nonlinearities. The numerical stability of the algorithm is verified. Simulation experiments for a small and moderate number of input-output data are presented and discussed to illustrate the applicability of the routine.
    Źródło:
    International Journal of Applied Mathematics and Computer Science; 2013, 23, 3; 507-520
    1641-876X
    2083-8492
    Pojawia się w:
    International Journal of Applied Mathematics and Computer Science
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Comparison of the results for calculation of vortex currents after sudden expansion of the pipe with different diameters
    Autorzy:
    Kholboev, B. M.
    Navruzov, D. P.
    Asrakulova, D. S.
    Engalicheva, N. R.
    Turemuratova, A. A.
    Powiązania:
    https://bibliotekanauki.pl/articles/2174200.pdf
    Data publikacji:
    2022
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    fluktuacja prędkości
    prąd wirowy
    anizotropia turbulencji
    two-fluid turbulence model
    sudden expansion
    velocity fluctuation
    intensity of fluctuations
    gas resistance
    quasi-periodic regime
    Opis:
    In this work, a numerical study of a sharply expanding highly swirling flow is carried out using v2-f models based on the Comsol Multiphysics 5.6 software package and a two-fluid turbulence model. The results obtained are compared with known experimental data with different pipe diameters. The purpose of this work is to test the ability of models to describe anisotropic turbulence. It is shown that the two-fluid model is more suitable for studying such flows.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2022, 27, 2; 115--123
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A dynamic bi-orthogonal field equation approach to efficient Bayesian inversion
    Autorzy:
    Tagade, P. M.
    Choi, H. L.
    Powiązania:
    https://bibliotekanauki.pl/articles/330516.pdf
    Data publikacji:
    2017
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    Bayesian framework
    stochastic partial differential equation
    Karhunen–Loève expansion
    generalized polynomial chaos
    dynamically biorthogonal field equations
    ramy Bayesa
    stochastyczne równanie różniczkowe
    przekształcenie Karhunena-Loeve'a
    chaos wielomianowy
    Opis:
    This paper proposes a novel computationally efficient stochastic spectral projection based approach to Bayesian inversion of a computer simulator with high dimensional parametric and model structure uncertainty. The proposed method is based on the decomposition of the solution into its mean and a random field using a generic Karhunen–Loève expansion. The random field is represented as a convolution of separable Hilbert spaces in stochastic and spatial dimensions that are spectrally represented using respective orthogonal bases. In particular, the present paper investigates generalized polynomial chaos bases for the stochastic dimension and eigenfunction bases for the spatial dimension. Dynamic orthogonality is used to derive closed-form equations for the time evolution of mean, spatial and the stochastic fields. The resultant system of equations consists of a partial differential equation (PDE) that defines the dynamic evolution of the mean, a set of PDEs to define the time evolution of eigenfunction bases, while a set of ordinary differential equations (ODEs) define dynamics of the stochastic field. This system of dynamic evolution equations efficiently propagates the prior parametric uncertainty to the system response. The resulting bi-orthogonal expansion of the system response is used to reformulate the Bayesian inference for efficient exploration of the posterior distribution. The efficacy of the proposed method is investigated for calibration of a 2D transient diffusion simulator with an uncertain source location and diffusivity. The computational efficiency of the method is demonstrated against a Monte Carlo method and a generalized polynomial chaos approach.
    Źródło:
    International Journal of Applied Mathematics and Computer Science; 2017, 27, 2; 229-243
    1641-876X
    2083-8492
    Pojawia się w:
    International Journal of Applied Mathematics and Computer Science
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-12 z 12

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