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Wyszukujesz frazę "nonlinear diffusion" wg kryterium: Temat

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    Wyświetlanie 1-9 z 9
    Tytuł:
    An improved diffusion driven watershed algorithm for image segmentation of cells
    Autorzy:
    Tarnawski, W.
    Kurzyński, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/333900.pdf
    Data publikacji:
    2007
    Wydawca:
    Uniwersytet Śląski. Wydział Informatyki i Nauki o Materiałach. Instytut Informatyki. Zakład Systemów Komputerowych
    Tematy:
    segmentacja obrazu
    dyfuzja nieliniowa
    segmentacja wododziałowa
    wykrywanie komórek
    image segmentation
    nonlinear diffusion
    watershed segmentation cell detection
    Opis:
    The image segmentation is one of the most crucial steps in automated analysis of medical and biological images. The segmentation process allows for a detection of object contours. Due to specificity of imaging technique, a correct detection of cell contours is problematic because of the fuzzy and broken edges. Moreover, the cells are very often connected. The modified watershed algorithm based on the diffusion model presented in this paper has been successfully applied to segmentation of cells where the mentioned difficulties appear. The method was tested in contact endoscopy, a novel technique in the diagnosis of the larynx.
    Źródło:
    Journal of Medical Informatics & Technologies; 2007, 11; 213-220
    1642-6037
    Pojawia się w:
    Journal of Medical Informatics & Technologies
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Nonlinear Interaction of Modes in a Planar Flow of a Gas with Viscous and Thermal Attenuation
    Autorzy:
    Perelomova, Anna
    Powiązania:
    https://bibliotekanauki.pl/articles/177137.pdf
    Data publikacji:
    2019
    Wydawca:
    Polska Akademia Nauk. Czasopisma i Monografie PAN
    Tematy:
    nonlinear wave theory
    nonlinear acoustics
    coupling dynamic equations
    Burgers equation
    diffusion equation
    Opis:
    The nonlinear interaction of wave and non-wave modes in a gas planar flow are considered. Attention is mainly paid to the case when one sound mode is dominant and excites the counter-propagating sound mode and the entropy mode. The modes are determined by links between perturbations of pressure, density, and fluid velocity. This definition follows from the linear conservation equations in the differentia form and thermodynamic equations of state. The leading order system of coupling equations for interacting modes is derived. It consists of diffusion inhomogeneous equations. The main aim of this study is to identify the principle features of the interaction and to establish individual contributions of attenuation (mechanical and thermal attenuation) in the solution to the system.
    Źródło:
    Archives of Acoustics; 2019, 44, 3; 551-559
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Global pointwise a priori bounds and large time behaviour for a nonlinear system describing the spread of infectious disease
    Autorzy:
    Kirane, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1340654.pdf
    Data publikacji:
    1993
    Wydawca:
    Polska Akademia Nauk. Instytut Matematyczny PAN
    Tematy:
    global existence
    nonlinear reaction-diffusion system
    large time behaviour
    Opis:
    This paper considers a reaction-diffusion system with biatic diffusion.Existence of a globally bounded solution is proved and its large timebehaviour is given.
    Źródło:
    Applicationes Mathematicae; 1993-1995, 22, 1; 1-9
    1233-7234
    Pojawia się w:
    Applicationes Mathematicae
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Integrated region-based segmentation using color components and texture features with prior shape knowledge
    Autorzy:
    Emambakhsh, M.
    Ebrahimnezhad, H.
    Sedaaghi, M. H.
    Powiązania:
    https://bibliotekanauki.pl/articles/908141.pdf
    Data publikacji:
    2010
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    segmentacja obrazów
    zbiór poziomicowy
    dyfuzja nieliniowa
    minimalizacja energii
    image segmentation
    prior shape knowledge
    level set
    nonlinear diffusion
    energy minimization
    Opis:
    Segmentation is the art of partitioning an image into different regions where each one has some degree of uniformity in its feature space. A number of methods have been proposed and blind segmentation is one of them. It uses intrinsic image features, such as pixel intensity, color components and texture. However, some virtues, like poor contrast, noise and occlusion, can weaken the procedure. To overcome them, prior knowledge of the object of interest has to be incorporated in a top-down procedure for segmentation. Consequently, in this work, a novel integrated algorithm is proposed combining bottom-up (blind) and top-down (including shape prior) techniques. First, a color space transformation is performed. Then, an energy function (based on nonlinear diffusion of color components and directional derivatives) is defined. Next, signeddistance functions are generated from different shapes of the object of interest. Finally, a variational framework (based on the level set) is employed to minimize the energy function. The experimental results demonstrate a good performance of the proposed method compared with others and show its robustness in the presence of noise and occlusion. The proposed algorithm is applicable in outdoor and medical image segmentation and also in optical character recognition (OCR).
    Źródło:
    International Journal of Applied Mathematics and Computer Science; 2010, 20, 4; 711-726
    1641-876X
    2083-8492
    Pojawia się w:
    International Journal of Applied Mathematics and Computer Science
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Nonlinear filtering for Markov systems with delayed observations
    Autorzy:
    Calzolari, A.
    Florchinger, P.
    Nappo, G.
    Powiązania:
    https://bibliotekanauki.pl/articles/907856.pdf
    Data publikacji:
    2009
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    filtracja nieliniowa
    proces dyfuzji
    procesy Markova
    stochastyczne równanie różniczkowe
    nonlinear filtering
    jump processes
    diffusion processes
    Markov processes
    stochastic delay differential equation
    Opis:
    This paper deals with nonlinear filtering problems with delays, i.e., we consider a system (X,Y ), which can be represented by means of a system [...], in the sense that [...], where a(t) is a delayed time transformation. We start with X being a Markov process, and then study Markovian systems, not necessarily diffusive, with correlated noises. The interest is focused on the existence of explicit representations of the corresponding filters as functionals depending on the observed trajectory. Various assumptions on the function a(t) are considered.
    Źródło:
    International Journal of Applied Mathematics and Computer Science; 2009, 19, 1; 49-57
    1641-876X
    2083-8492
    Pojawia się w:
    International Journal of Applied Mathematics and Computer Science
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Nonlocal quadratic evolution problems
    Autorzy:
    Biler, Piotr
    Woyczyński, Wojbor
    Powiązania:
    https://bibliotekanauki.pl/articles/1207633.pdf
    Data publikacji:
    2000
    Wydawca:
    Polska Akademia Nauk. Instytut Matematyczny PAN
    Tematy:
    self-similar solutions
    fractal anomalous diffusion
    asymptotic behavior of solutions
    nonlinear nonlocal parabolic equations
    Opis:
    Nonlinear nonlocal parabolic equations modeling the evolution of density of mutually interacting particles are considered. The inertial type nonlinearity is quadratic and nonlocal while the diffusive term, also nonlocal, is anomalous and fractal, i.e., represented by a fractional power of the Laplacian. Conditions for global in time existence versus finite time blow-up are studied. Self-similar solutions are constructed for certain homogeneous initial data. Monte Carlo approximation schemes by interacting particle systems are also mentioned.
    Źródło:
    Banach Center Publications; 2000, 52, 1; 11-24
    0137-6934
    Pojawia się w:
    Banach Center Publications
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Solution of linear and nonlinear diffusion problems via stochastic differential equations
    Autorzy:
    Bargieł, M.
    Tory, E. M.
    Powiązania:
    https://bibliotekanauki.pl/articles/305261.pdf
    Data publikacji:
    2015
    Wydawca:
    Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
    Tematy:
    nonlinear diffusion
    stochastic differential equations
    Wiener process
    Itô process
    Kolmogorov backward equation
    Opis:
    The equation for nonlinear diffusion can be rearranged to a form that immediately leads to its stochastic analog. The latter contains a drift term that is absent when the diffusion coefficient is constant. The dependence of this coefficient on concentration (or temperature) is handled by generating many paths in parallel and approximating the derivative of concentration with respect to distance by the central difference. This method works for one-dimensional diffusion problems with finite or infinite boundaries and for diffusion in cylindrical or spherical shells. By mimicking the movements of molecules, the stochastic approach provides a deeper insight into the physical process. The parallel version of our algorithm is very efficient. The 99% confidence limits for the stochastic solution enclose the analytical solution so tightly that they cannot be shown graphically. This indicates that there is no systematic difference in the results for the two methods. Finally, we present a direct derivation of the stochastic method for cylindrical and spherical shells.
    Źródło:
    Computer Science; 2015, 16 (4); 415-428
    1508-2806
    2300-7036
    Pojawia się w:
    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:
    Triple diffusive flow of Casson nanofluid with buoyancy forces and nonlinear thermal radiation over a horizontal plate
    Autorzy:
    Archana, Manjappa
    Gireesha, Bijjanal Jayanna
    Prasannakumara, Ballajja Chandrappa
    Powiązania:
    https://bibliotekanauki.pl/articles/240608.pdf
    Data publikacji:
    2019
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    triple diffusion
    casson nanofluid
    nonlinear thermal radiation
    buoyancy force
    siła wyporu
    promieniowanie cieplne
    Opis:
    The presence of more than one solute diffused in fluid mixtures is very often requested for discussing the natural phenomena such as transportation of contaminants, underground water, acid rain and so on. In the paper, the effect of nonlinear thermal radiation on triple diffusive convective boundary layer flow of Casson nanofluid along a horizontal plate is theoretically investigated. Similarity transformations are utilized to reduce the governing partial differential equations into a set of nonlinear ordinary differential equations. The reduced equations are numerically solved using Runge-Kutta-Fehlberg fourth-fifth order method along with shooting technique. The impact of several existing physical parameters on velocity, temperature, solutal and nanofluid concentration profiles are analyzed through graphs and tables in detail. It is found that, modified Dufour parameter and Dufour solutal Lewis number enhances the temperature and solutal concentration profiles respectively.
    Źródło:
    Archives of Thermodynamics; 2019, 40, 1; 49-69
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-9 z 9

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