Informacja

Drogi użytkowniku, aplikacja do prawidłowego działania wymaga obsługi JavaScript. Proszę włącz obsługę JavaScript w Twojej przeglądarce.

English (EN)·Polski (PL)·Yкраїнський (UK)
Przejdź do strony domowej biblioteki Centralna Biblioteka Wojskowa Link otwiera się w nowym oknie Logo biblioteki Prolib Integro - strona głównaCentralna Biblioteka Wojskowa

Wyszukujesz frazę "gradient" wg kryterium: Temat

  Lista filtrów
Wyrównaj
Wyświetlanie 1-15 z 23
Tytuł:
Gradient Observability for Diffusion Systems
Autorzy:
Zerrik, E. H.
Bourray, H.
Powiązania:
https://bibliotekanauki.pl/articles/908195.pdf
Data publikacji:
2003
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
informatyka
diffusion system
observability
regional gradient observability
gradient strategic sensor
gradient reconstruction
Opis:
The aim of this paper is to study regional gradient observability for a diffusion system and the reconstruction of the state gradient without the knowledge of the state. First, we give definitions and characterizations of these new concepts and establish necessary conditions for the sensor structure in order to obtain regional gradient observability. We also explore an approach which allows for a regional gradient reconstruction. The developed method is original and leads to a numerical algorithm illustrated by simulations.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2003, 13, 2; 139-150
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Operator-splitting and Lagrange multiplier domain decomposition methods for numerical simulation of two coupled Navier-Stokes fluids
Autorzy:
Bresch, D.
Koko, J.
Powiązania:
https://bibliotekanauki.pl/articles/908383.pdf
Data publikacji:
2006
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
dwoistość
gradient sprzężony
przepływ Naviera-Stokesa
domain decomposition
duality
conjugate gradient
Navier-Stokes flows
Opis:
We present a numerical simulation of two coupled Navier-Stokes flows, using operator-splitting and optimization-based nonoverlapping domain decomposition methods. The model problem consists of two Navier-Stokes fluids coupled, through a common interface, by a nonlinear transmission condition. Numerical experiments are carried out with two coupled fluids; one with an initial linear profile and the other in rest. As expected, the transmission condition generates a recirculation within the fluid in rest.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2006, 16, 4; 419-429
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A proximal-based algorithm for piecewise sparse approximation with application to scattered data fitting
Autorzy:
Zhong, Yijun
Li, Chongjun
Li, Zhong
Duan, Xiaojuan
Powiązania:
https://bibliotekanauki.pl/articles/2172132.pdf
Data publikacji:
2022
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
piecewise sparse approximation
proximal gradient
scattered data fitting
aproksymacja rzadka
gradient proksymalny
dopasowanie danych
Opis:
In some applications, there are signals with a piecewise structure to be recovered. In this paper, we propose a piecewise sparse approximation model and a piecewise proximal gradient method (JPGA) which aim to approximate piecewise signals. We also make an analysis of the JPGA based on differential equations, which provides another perspective on the convergence rate of the JPGA. In addition, we show that the problem of sparse representation of the fitting surface to the given scattered data can be considered as a piecewise sparse approximation. Numerical experimental results show that the JPGA can not only effectively fit the surface, but also protect the piecewise sparsity of the representation coefficient.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2022, 32, 4; 671--682
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A study on vibration of tapered non-homogeneous rectangular plate with structural parameters
Autorzy:
Kaur, N.
Singhal, A.
Khanna, A.
Powiązania:
https://bibliotekanauki.pl/articles/265369.pdf
Data publikacji:
2018
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
wibracje
niejednorodność
gradient termiczny
parametr stożka
vibration
non-homogeneity
thermal gradient
taper parameter
simply supported
aspect ratio
Opis:
Effects of structural parameters on the vibration of a tapered non-homogeneous rectangular plate with different combinations of boundary conditions are discussed. Tapering in the plate is assumed to be sinusoidal in the x-direction. Here, temperature variation and non-homogeneity in the plate material are also considered sinusoidal in the x-direction. The Rayleigh-Ritz method is used to calculate the frequency parameter for the first two modes of vibration for different values of the structural parameters, i.e. the taper parameter, thermal gradient, aspect ratio and non-homogeneity constant. Results are obtained for three boundary conditions, i.e. clamped boundary (C-C-C-C), simply supported boundary (SS-SS-SS-SS) and clamped-simply supported boundary (CSS-C-SS). Numerical values of the frequency parameter are given in a compact tabular form.
Źródło:
International Journal of Applied Mechanics and Engineering; 2018, 23, 4; 873-884
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Regional Gradient Controllability of Parabolic Systems
Autorzy:
Zerrik, E.
Boutoulout, A.
Kamal, A.
Powiązania:
https://bibliotekanauki.pl/articles/908270.pdf
Data publikacji:
1999
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
układ paraboliczny
sterowność
parabolic systems
regional gradient controllability
G-strategic actuator
Opis:
The purpose of this paper is to show for parabolic systems how one can achieve a final gradient in a subregion w of the system domain W. First, we give a definition and delineate some properties of this new concept, and then we introduce the concept of regionally gradient strategic actuators. The importance of the spatial structure and location of the actuators in achieving regional gradient controllability is emphasized. Consequently, we concentrate on the determination of a control which would realize a given final gradient on w with minimum energy. The developed approach is original and leads to numerical algorithms for constructing optimal controls. This approach is also illustrated by an example.
Źródło:
International Journal of Applied Mathematics and Computer Science; 1999, 9, 4; 767-787
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Accurate gradient computations at interfaces using finite element methods
Autorzy:
Qin, F.
Wang, Z.
Ma, Z.
Li, Z.
Powiązania:
https://bibliotekanauki.pl/articles/330659.pdf
Data publikacji:
2017
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
elliptic interface problem
gradient flux computation
IFEM
mixed FE formulation
computational tube
Opis:
New finite element methods are proposed for elliptic interface problems in one and two dimensions. The main motivation is to get not only an accurate solution, but also an accurate first order derivative at the interface (from each side). The key in 1D is to use the idea of Wheeler (1974). For 2D interface problems, the point is to introduce a small tube near the interface and propose the gradient as part of unknowns, which is similar to a mixed finite element method, but only at the interface. Thus the computational cost is just slightly higher than in the standard finite element method. We present a rigorous one dimensional analysis, which shows a second order convergence order for both the solution and the gradient in 1D. For two dimensional problems, we present numerical results and observe second order convergence for the solution, and super-convergence for the gradient at the interface.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2017, 27, 3; 527-537
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Two implementations of the preconditioned conjugate gradient method on heterogeneous computing grids
Autorzy:
Collignon, T. P.
Van Gijzen, M. B.
Powiązania:
https://bibliotekanauki.pl/articles/907778.pdf
Data publikacji:
2010
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
przetwarzanie siatkowe
system liniowy
metoda iteracyjna
gradient sprzężony
przepływ pęcherzykowy
grid computing
large sparse linear systems
iterative methods
conjugate gradient method
Chronopoulos/Gear CG
GridSolve middleware
bubbly flows
Opis:
Efficient iterative solution of large linear systems on grid computers is a complex problem. The induced heterogeneity and volatile nature of the aggregated computational resources present numerous algorithmic challenges. This paper describes a case study regarding iterative solution of large sparse linear systems on grid computers within the software constraints of the grid middleware GridSolve and within the algorithmic constraints of preconditioned Conjugate Gradient (CG) type methods. We identify the various bottlenecks induced by the middleware and the iterative algorithm. We consider the standard CG algorithm of Hestenes and Stiefel, and as an alternative the Chronopoulos/Gear variant, a formulation that is potentially better suited for grid computing since it requires only one synchronisation point per iteration, instead of two for standard CG. In addition, we improve the computation-to-communication ratio by maximising the work in the preconditioner. In addition to these algorithmic improvements, we also try to minimise the communication overhead within the communication model currently used by the GridSolve middleware. We present numerical experiments on 3D bubbly flow problems using heterogeneous computing hardware that show lower computing times and better speed-up for the Chronopoulos/Gear variant of conjugate gradients. Finally, we suggest extensions to both the iterative algorithm and the middleware for improving granularity.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2010, 20, 1; 109-121
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Gradient flow optimization for reducing blocking effects of transform coding
Autorzy:
Gao, F.
Li, X.
Wang, X.
Wee, W. G.
Powiązania:
https://bibliotekanauki.pl/articles/907251.pdf
Data publikacji:
2004
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
przepływ gradientu
efekt blokowania
kodowanie transformatowe
gradient flow
blocking effects
optimization
transform coding
Opis:
This paper addresses the problem of reducing blocking effects in transform coding. A novel optimization approach using the gradient flow is proposed. Using some properties of the gradient flow on a manifold, an optimized filter design method for reducing the blocking effects is presented. Based on this method, an image reconstruction algorithm is derived. The algorithm maintains the fidelity of images while reducing the blocking effects. Experimental tests demonstrate that the presented algorithm is effective.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2004, 14, 1; 105-111
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Convergence Analysis for Principal Component Flows
Autorzy:
Yoshizawa, S.
Helmke, U.
Starkov, K.
Powiązania:
https://bibliotekanauki.pl/articles/908317.pdf
Data publikacji:
2001
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
badanie zbieżności
sieć neuronowa
principal component analysis
neural networks
gradient flows
phase portrait
Hessians
Opis:
A common framework for analyzing the global convergence of several flows for principal component analysis is developed. It is shown that flows proposed by Brockett, Oja, Xu and others are all gradient flows and the global convergence of these flows to single equilibrium points is established. The signature of the Hessian at each critical point is determined.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2001, 11, 1; 223-236
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effects of rotation on transient fluid flow and heat transfer through a curved square duct: the case of negative rotation
Autorzy:
Hasan, Mohammad Sanjeed
Mollah, Md. Tusher
Kumar, Dipankar
Mondal, Rabindra Nath
Lorenzini, Giulio
Powiązania:
https://bibliotekanauki.pl/articles/2106459.pdf
Data publikacji:
2021
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
przepływ
temperatura
walidacja eksperymentalna
flow transition
temperature gradient
unsteady and vortex diagram
experimental validation
Opis:
The fluid flow and heat transfer through a rotating curved duct has received much attention in recent years because of vast applications in mechanical devices. It is noticed that there occur two different types of rotations in a rotating curved duct such as positive and negative rotation. The positive rotation through the curved duct is widely investigated while the investigation on the negative rotation is rarely available. The paper investigates the influence of negative rotation for a wide range of Taylor number [...] when the duct itself rotates about the center of curvature. Due to the rotation, three types of forces including Coriolis, centrifugal, and buoyancy forces are generated. The study focuses and explains the combined effect of these forces on the fluid flow in details. First, the linear stability of the steady solution is performed. An unsteady solution is then obtained by time-evolution calculation and flow transition is determined by calculating phase space and power spectrum. When Tr is raised in the negative direction, the flow behavior shows different flow instabilities including steady-state, periodic, multi-periodic, and chaotic oscillations. Furthermore, the pattern variations of axial and secondary flow velocity and isotherms are obtained, and it is found that there is a strong interaction between the flow velocities and the isotherms. Then temperature gradients are calculated which show that the fluid mixing and the acts of secondary flow have a strong influence on heat transfer in the fluid. Diagrams of unsteady flow and vortex structure are further sketched and precisely elucidate the curvature effects on unsteady fluid flow. Finally, a comparison between the numerical and experimental data is discussed which demonstrates that both data coincide with each other.
Źródło:
International Journal of Applied Mechanics and Engineering; 2021, 26, 4; 29--50
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Newtons iteration with a conjugate gradient based decomposition method for an elliptic PDE with a nonlinear boundary condition
Autorzy:
Koko, J.
Powiązania:
https://bibliotekanauki.pl/articles/907312.pdf
Data publikacji:
2004
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
metoda Newtona
metoda gradientu sprzężonego
warunek brzegowy nieliniowy
Newton's method
conjugate gradient method
nonlinear PDE
Opis:
Newton's iteration is studied for the numerical solution of an elliptic PDE with nonlinear boundary conditions. At each iteration of Newton's method, a conjugate gradient based decomposition method is applied to the matrix of the linearized system. The decomposition is such that all the remaining linear systems have the same constant matrix. Numerical results confirm the savings with respect to the computational cost, compared with the classical Newton method with factorization at each step.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2004, 14, 1; 13-18
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the Choice of Subspace for Iterative Methods for Linear Discrete Ill-Posed Problems
Autorzy:
Calvetti, D.
Lewis, B.
Reichel, L.
Powiązania:
https://bibliotekanauki.pl/articles/908057.pdf
Data publikacji:
2001
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
metoda sprzężonych gradientów
problem niewłaściwie postawiony
minimal residual method
conjugate gradient method
ill-posed problems
Opis:
Many iterative methods for the solution of linear discrete ill-posed problems with a large matrix require the computed approximate solutions to be orthogonal to the null space of the matrix. We show that when the desired solution is not smooth, it may be possible to determine meaningful approximate solutions with less computational work by not imposing this orthogonality condition.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2001, 11, 5; 1069-1092
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Transient flow through a porous channel with ramped pressure gradient and velocity slip boundary condition
Autorzy:
Jha, Basant K.
Yunus, Zainab Sa'id
Powiązania:
https://bibliotekanauki.pl/articles/2174168.pdf
Data publikacji:
2022
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
przepływ przejściowy
prędkość
ciśnienie
transient flow
velocity slip
ramped pressure gradient
Riemann-Sum approximation technique
Opis:
A transient flow formation of an incompressible fluid through a horizontal porous channel assuming a ramped pressure gradient is considered with the velocity slip boundary conditions. The flow is a laminar flow caused by ramped pressure gradient along the flow direction. The equation governing the flow is modeled, and solved by the Laplace transformation technique to obtain a semi-analytical solution under slip boundary conditions. It was noted that the flow velocity increases as the slip parameter is increased.
Źródło:
International Journal of Applied Mechanics and Engineering; 2022, 27, 1; 78--90
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effects of pressure gradient on convective heat transfer in a boundary layer flow of a Maxwell fluid past a stretching sheet
Autorzy:
Kashif, A. N.
Salah, F.
Sankar, D. S.
Izyan, M. D. N.
Viswanathan, K. K.
Powiązania:
https://bibliotekanauki.pl/articles/2106449.pdf
Data publikacji:
2021
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
płyn Maxwell'a
przenoszenie ciepła
rozciąganie
pressure gradient parameter
convective heat transfer
Maxwell fluid
stretching sheet
Opis:
The pressure gradient term plays a vital role in convective heat transfer in the boundary layer flow of a Maxwell fluid over a stretching sheet. The importance of the effects of the term can be monitored by developing Maxwell’s equation of momentum and energy with the pressure gradient term. To achieve this goal, an approximation technique, i.e. Homotopy Perturbation Method (HPM) is employed with an application of algorithms of Adams Method (AM) and Gear Method (GM). With this approximation method we can study the effects of the pressure gradient [...], Deborah number [...], the ratio of the free stream velocity parameter to the stretching sheet parameter [...] and Prandtl number [...] on both the momentum and thermal boundary layer thicknesses. The results have been compared in the absence and presence of the pressure gradient term m. It has an impact of thinning of the momentum and boundary layer thickness for non-zero values of the pressure gradient. The convergence of the system has been taken into account for the stretching sheet parameter. The result of the system indicates the significant thinning of the momentum and thermal boundary layer thickness in velocity and temperature profiles.
Źródło:
International Journal of Applied Mechanics and Engineering; 2021, 26, 3; 104--118
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
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
Wyświetlanie 1-15 z 23

Ta witryna wykorzystuje pliki cookies do przechowywania informacji na Twoim komputerze. Pliki cookies stosujemy w celu świadczenia usług na najwyższym poziomie, w tym w sposób dostosowany do indywidualnych potrzeb. Korzystanie z witryny bez zmiany ustawień dotyczących cookies oznacza, że będą one zamieszczane w Twoim komputerze. W każdym momencie możesz dokonać zmiany ustawień dotyczących cookies