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 1-13 z 13
    Tytuł:
    New estimate for the curvature of an order-convex set and related questions
    Autorzy:
    Ramazanov, Ali B.
    Powiązania:
    https://bibliotekanauki.pl/articles/2050043.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Instytut Badań Systemowych PAN
    Tematy:
    gradient
    estimates
    curvature
    convexity
    algorithm
    Opis:
    It is well known that in discrete optimization problems, gradient (local) algorithms do not always guarantee an optimal solution. Therefore, the problem arises of finding the accuracy of the gradient algorithm. This is a fairly well-known problem and numerous publications have been devoted to it. In establishing accuracy, various approaches are used. One of these approaches is to obtain guaranteed estimates of the accuracy of the gradient algorithm in terms of the curvature of the admissible domain. With this approach, it is required to find the curvatures of the admissible region. Since finding the exact value of curvature is a difficult problem to solve, curvature estimates in terms of more or less simply calculated parameters of the problem are relevant. A new improved bound for the curvature of an order-convex set is found and is presented in this paper in terms of the steepness and parameters of strict convexity of the function.
    Źródło:
    Control and Cybernetics; 2020, 49, 2; 233-240
    0324-8569
    Pojawia się w:
    Control and Cybernetics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    On stability analysis in shape optimisation : critical shapes for Neumann problem
    Autorzy:
    Dambrine, M.
    Sokolowski, J.
    Żochowski, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/970525.pdf
    Data publikacji:
    2003
    Wydawca:
    Polska Akademia Nauk. Instytut Badań Systemowych PAN
    Tematy:
    optymalizacja kształtu
    analiza stabilności
    gradient kształtu
    shape optimisation
    stability analysis
    shape gradient
    shape Hessian
    Opis:
    The stability issue of critical shapes for shape optimization problems with the state function given by a solution to the Neumann problem for the Laplace equation is considered. To this end, the properties of the shape Hessian evaluated at critical shapes are analysed. First, it is proved that the stability cannot be expected for the model problem. Then, the new estimates for the shape Hessian are derived in order to overcome the classical two norms-discrepancy well know in control problems, Malanowski (2001). In the context of shape optimization, the situation is similar compared to control problems, actually, the shape Hessian can be coercive only in the norm strictly weaker with respect to the norm of the second order differentiability of the shape functional. In addition, it is shown that an appropriate regularization makes possible the stability of critical shapes.
    Źródło:
    Control and Cybernetics; 2003, 32, 3; 503-528
    0324-8569
    Pojawia się w:
    Control and Cybernetics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Structural optimization using topological and shape sensitivity via a level set method
    Autorzy:
    Allaire, G.
    Gournay, F. de
    Jouve, F.
    Toader, A.-M.
    Powiązania:
    https://bibliotekanauki.pl/articles/970155.pdf
    Data publikacji:
    2005
    Wydawca:
    Polska Akademia Nauk. Instytut Badań Systemowych PAN
    Tematy:
    optymalizacja kształtu i topologiczna
    gradient topologiczny
    shape and topology optimization
    level set method
    topological gradient
    Opis:
    A numerical coupling of two recent methods in shape and topology optimization of structures is proposed. On the one hand, the level set method, based on the classical shape derivative, is known to easily handle boundary propagation with topological changes. However, in practice it does not allow for the nucleation of new holes (at least in 2-d). On the other hand, the bubble or topological gradient method is precisely designed for introducing new holes in the optimization process. Therefore, the coupling of these two method yields an efficient, algorithm which can escape from local minima in a given topological class of shapes. Both methods rely on the notion of gradient computed through an adjoint analysis, and have a low CPU cost since they capture a shape on a fixed Eulerian mesh. The main advantage of our coupled algorithm is to make the resulting optimal design largely independent of the initial guess.
    Źródło:
    Control and Cybernetics; 2005, 34, 1; 59-80
    0324-8569
    Pojawia się w:
    Control and Cybernetics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A sufficient condition for optimality in nondifferentiable invex programming
    Autorzy:
    Antczak, T.
    Powiązania:
    https://bibliotekanauki.pl/articles/205838.pdf
    Data publikacji:
    2001
    Wydawca:
    Polska Akademia Nauk. Instytut Badań Systemowych PAN
    Tematy:
    funkcja półwypukła
    uogólniony gradient Clarka
    Clarke's generalized gradient
    invex function
    locally Lipschitz function
    semiconvex function
    Opis:
    In this paper sufficient optimality condition are established for a nonlinear programming problem without differentiability assumption on the data wherein Clarke's generalized gradient is used to define invexity.
    Źródło:
    Control and Cybernetics; 2001, 30, 4; 431-437
    0324-8569
    Pojawia się w:
    Control and Cybernetics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Crack detection by the topological gradient method
    Autorzy:
    Amstutz, S.
    Horchani, I.
    Masmoudi, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/970147.pdf
    Data publikacji:
    2005
    Wydawca:
    Polska Akademia Nauk. Instytut Badań Systemowych PAN
    Tematy:
    wykrywanie pęknięć
    wrażliwość topologiczna
    gradient topologiczny
    równanie Poissona
    crack detection
    topological sensitivity
    topological gradient
    Poisson equation
    Opis:
    The topological sensitivity analysis consists in studying the behavior of a shape functional when modifying the topology of the domain. In general, the perturbation under consideration is the creation of a small hole. In this paper, the topological asymptotic expansion is obtained for the Laplace equation with respect to the insertion of a short crack inside a plane domain. This result is illustrated by some numerical experiments in the context of crack detection.
    Źródło:
    Control and Cybernetics; 2005, 34, 1; 81-101
    0324-8569
    Pojawia się w:
    Control and Cybernetics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    On convergence of the Monotone Structural Evolution
    Autorzy:
    Korytowski, A.
    Szymkat, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/206572.pdf
    Data publikacji:
    2016
    Wydawca:
    Polska Akademia Nauk. Instytut Badań Systemowych PAN
    Tematy:
    optimal control
    direct computational methods
    gradient optimization
    monotone structural evolution
    Opis:
    The paper studies convergenceof the Monotone Structural Evolution (MSE), a computational method of optimal control. The principles of MSE are described and an expository example presents the method in action. It is then proved that under appropriate assumptions the method is convergent to the decision space stationarity conditions. Observations on finite convergence and on connections with Pontryagin’s maximum principle are also provided.
    Źródło:
    Control and Cybernetics; 2016, 45, 4; 483-512
    0324-8569
    Pojawia się w:
    Control and Cybernetics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Shape sensitivity analysis of time-dependent flows of incompressible non-Newtonian fluids
    Autorzy:
    Sokołowski, J.
    Stebel, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/206105.pdf
    Data publikacji:
    2011
    Wydawca:
    Polska Akademia Nauk. Instytut Badań Systemowych PAN
    Tematy:
    shape optimization
    shape gradient
    incompressible viscous fluid
    Navier-Stokes equations
    Opis:
    We study the shape differentiability of a cost function for the flow of an incompressible viscous fluid of power-law type. The fluid is confined to a bounded planar domain surrounding an obstacle. For smooth perturbations of the shape of the obstacle we express the shape gradient of the cost function which can be subsequently used to improve the initial design.
    Źródło:
    Control and Cybernetics; 2011, 40, 4; 1077-1097
    0324-8569
    Pojawia się w:
    Control and Cybernetics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Shape optimization for stationary Navier-Stokes equations
    Autorzy:
    Halanay, A.
    Tiba, D.
    Powiązania:
    https://bibliotekanauki.pl/articles/970751.pdf
    Data publikacji:
    2009
    Wydawca:
    Polska Akademia Nauk. Instytut Badań Systemowych PAN
    Tematy:
    optimal design
    optimal control method
    fluid mechanics
    penalization
    gradient method
    Opis:
    This work discusses geometric optimization problems governed by stationary Navier-Stokes equations. Optimal domains are proved to exist under the assumption that the family of admissible domains is bounded and satisfies the Lipschitz condition with a uniform constant, and in the absence of the uniqueness property for the state system. Through the parametrization of the admissible shapes by continuous functions defined on a larger universal domain, the optimization parameter becomes a control, i.e. an element of that family of continuous functions. The approximating extension technique via the penalization of the Navier-Stokes equation enables the approximation of the associated shape optimization problem by an optimal control problem. Results on existence and uniqueness are proved for the approximating problem and a gradient-type algorithm is indicated.
    Źródło:
    Control and Cybernetics; 2009, 38, 4B; 1359-1374
    0324-8569
    Pojawia się w:
    Control and Cybernetics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Second-order optimality conditions for semilinear elliptic control problems with constraints on the gradient of the state
    Autorzy:
    Casas, E.
    Fernandez, J.
    Mateos, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/206719.pdf
    Data publikacji:
    1999
    Wydawca:
    Polska Akademia Nauk. Instytut Badań Systemowych PAN
    Tematy:
    sterowanie optymalne
    optimal control
    second order conditions
    semilinear elliptic PDE
    state gradient constraints
    Opis:
    The aim of this paper is to state the second order necessary and sufficient optimality conditions for distributed control problems governed by the Neumann problem associated to a semilinear elliptic partial differential equation. Bound constraints ou control are considered, as well as equality and inequality constraints of integral type on the gradient of the state.
    Źródło:
    Control and Cybernetics; 1999, 28, 3; 463-479
    0324-8569
    Pojawia się w:
    Control and Cybernetics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Shape sensitivity of optimal control for the Stokes problem
    Autorzy:
    Abdelbari, Merwan
    Nachi, Khadra
    Sokolowski, Jan
    Szulc, Katarzyna
    Powiązania:
    https://bibliotekanauki.pl/articles/2049935.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Instytut Badań Systemowych PAN
    Tematy:
    Stokes equations
    optimal control problem
    coupled partial differential equations
    shape optimization
    shape gradient
    Opis:
    In this article, we study the shape sensitivity of optimal control for the steady Stokes problem. The main goal is to obtain a robust representation for the derivatives of optimal solution with respect to smooth deformation of the flow domain. We introduce in this paper a rigorous proof of existence of the material derivative in the sense of Piola, as well as the shape derivative for the solution of the optimality system. We apply these results to derive the formulae for the shape gradient of the cost functional; under some regularity conditions the shape gradient is given according to the structure theorem by a function supported on the moving boundary, then the numerical methods for shape optimization can be applied in order to solve the associated optimization problems.
    Źródło:
    Control and Cybernetics; 2020, 49, 1; 11-40
    0324-8569
    Pojawia się w:
    Control and Cybernetics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Approximate gradient projection method with general Runge-Kutta schemes and piecewise polynomial controls for optimal control problems
    Autorzy:
    Chryssoverghi, I.
    Powiązania:
    https://bibliotekanauki.pl/articles/970094.pdf
    Data publikacji:
    2005
    Wydawca:
    Polska Akademia Nauk. Instytut Badań Systemowych PAN
    Tematy:
    dyskretyzacja
    sterowanie optymalne
    optimal control
    gradient projection method
    discretization
    non-matching Runge-Kutta schemes
    piecewise polynomial controls
    Opis:
    This paper addresses the numerical solution of optimal control problems for systems described by ordinary differential equations with control constraints. The state equation is discretized by a general explicit Runge-Kutta scheme and the controls are approximated by functions that are piecewise polynomial, but not necessarily continuous. We then propose an approximate gradient projection method that constructs sequences of discrete controls and progressively refines the discretization. Instead of using the exact discrete cost derivative, which usually requires tedious calculations, we use here an approximate derivative of the cost functional denned by discretizing the continuous adjoint equation by the same Runge-Kutta scheme backward and the integral involved by a Newton-Cotes integration rule, both involving maximal order intermediate approximations. The main result is that strong accumulation points in L2, if they exist, of sequences generated by this method satisfy the weak necessary conditions for optimality for the continuous problem. In the unconstrained case and under additional assumptions, we prove strong convergence in L2 and derive an a posteriori error estimate. Finally, numerical examples are given.
    Źródło:
    Control and Cybernetics; 2005, 34, 2; 425-451
    0324-8569
    Pojawia się w:
    Control and Cybernetics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Sub-gradient algorithms for computation of extreme eigenvalues of a real symmetric matrix
    Autorzy:
    Yassine, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/205834.pdf
    Data publikacji:
    1998
    Wydawca:
    Polska Akademia Nauk. Instytut Badań Systemowych PAN
    Tematy:
    problem wartości własnej
    difference of convex functions
    eigenvalue problems
    Lagrangian duality
    non-convex optimization
    sub-gradient algorithms
    Opis:
    The computation of eigenvalues of a matrix is still of importance from both theoretical and practical points of view. This is a significant problem for numerous industrial and scientific situations, notably in dynamics of structures (e.g. Gerardin, 1984), physics (e.g. Rappaz, 1979), chemistry (e.g. Davidson, 1983), economy (e.g. Morishima, 1971; Neumann, 1946), mathematics (e.g. Golub, 1989; Chatelin, 1983, 1984, 1988). The study of eigenvalue problems remains a delicate task, which generally presents numerical difficulties in relation to its sensivity to roundoff errors that may lead to numerical unstabilities, particularly if the eigenvalues are not well separated. In this paper, new subgradient-algorithms for computation of extreme eigenvalues of a symmetric real matrix are presented. Those algorithms are based on stability of Lagrangian duality for non-convex optimization and on duality in the difference of convex functions. Some experimental results which prove the robustness and efficiency of our algorithms are provided.
    Źródło:
    Control and Cybernetics; 1998, 27, 3; 387-415
    0324-8569
    Pojawia się w:
    Control and Cybernetics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Boundary optimal control problem for the phase-field transition system using fractional steps method
    Zadanie sterowania optymalnego brzegiem dla układu pola ze zmianą fazy z wykorzystaniem metody kroków ułamkowych
    Autorzy:
    Moroşanu, C.
    Powiązania:
    https://bibliotekanauki.pl/articles/206721.pdf
    Data publikacji:
    2003
    Wydawca:
    Polska Akademia Nauk. Instytut Badań Systemowych PAN
    Tematy:
    zagadnienie ze swobodnym brzegiem
    sterowanie optymalne
    metoda kroków ułamkowych
    warunki optymalności
    metoda elementu skończonego
    metoda gradientowa
    układ ze zmianą fazy
    phase-field transition system
    free boundary problem
    optimal control
    fractional steps method
    optimality conditions
    finite element method
    gradient method
    Opis:
    In this paper we prove the convergence of an iterative scheme of fractional steps type for boundary optimal control problem which is governed by the phase-field transition system. The existence of an optimal control and necessary optimality conditions are given for approximating problem. A gradient type algorithm and numerical implementation of this algorithm are discussed.
    W artykule dowodzi się zbieżności procedury iteracyjnej typu kroków ułamkowych dla zagadnienia sterowania optymalnego brzegiem w układzie pola ze zmianą fazy. Wykazano istnienie sterowania optymalnego i podano warunki konieczne optymalności dla zagadnienia aproksymującego. Rozpatrzono odpowiedni algorytm gradientowy oraz realizację numeryczną tego algorytmu.
    Źródło:
    Control and Cybernetics; 2003, 32, 1; 5-32
    0324-8569
    Pojawia się w:
    Control and Cybernetics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-13 z 13

      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