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Wyświetlanie 1-15 z 37
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:
Time-parametric control : uniform convergence of the optimal value functions of discretized problems
Autorzy:
Gugat, M.
Powiązania:
https://bibliotekanauki.pl/articles/206773.pdf
Data publikacji:
1999
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
ciąg
dyskretyzacja
funkcja celu
optymalizacja parametryczna
profil momentu
systemy sterowania minimalno-czasowe
warunek Hoeldera
warunek Lipschitza
zbieżność jednakowa
continuity
discretization
Hoelder condition
Lipschitz condition
moment problems
optimal value function
parametric optimization
time-minimal control
uniform convergence
Opis:
The problem of time-optimal control of linear hyperbolic systems is equivalent to the computation of the root of the optimal value function of a time-parametric program, whose feasible set is described by a countable system of moment equations. To compute this root, discretized problems with a finite number of equality constraints can be used. In this paper, we show that on a certain time-interval, the optimal value functions of the discretized problems converge uniformly to the optimal value function of the original problem. We also give sufficient conditions fot Lipschitz and Hoelder continuity of the optimal value function of the original problem.
Źródło:
Control and Cybernetics; 1999, 28, 1; 7-33
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Topological derivative for optimal control problems
Autorzy:
Sokołowski, J.
Żochowski, A.
Powiązania:
https://bibliotekanauki.pl/articles/206790.pdf
Data publikacji:
1999
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
sterowanie optymalne
asymptotic expansion
control problems
shape derivative
shape optimization
topological derivative
Opis:
The topological derivative is introduced for the extremal values of cost functionals for control problems. The optimal control problem considered in the paper is defined for the elliptic equation which models the deflection of an elastic membrane. The derivative measures the sensitivity of the optimal value of the cost with respect to changes in topology. A change in topology means removing a small ball from the interior of the domain of integration. The topological derivative can be used for obtaining the numerical solutions of the shape optimization problems.
Źródło:
Control and Cybernetics; 1999, 28, 3; 611-625
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Exponential and chaotic neurodynamical tabu searches for quadratic assignment problems
Autorzy:
Hasegawa, M.
Ikeguchi, T.
Aihara, K.
Powiązania:
https://bibliotekanauki.pl/articles/206864.pdf
Data publikacji:
2000
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
problem optymalizacji kombinatorycznej
sieć neuronowa
chaos
combinatorial optimization problems
neural networks
quadratic assignment problems
tabu search
Opis:
We propose a chaotic neurodynamical searching method for the Quadratic Assignment Problems (QAPs). First, we construct a neural network whose behavior is the same as that of the conventional tabu search. Using the dynamics of the tabu search neural network, we realize the exponential tabu search, whose tabu effect decreases exponentially with time, and we show the effectiveness of this type of exponential tabu search. Next, we extend this novel tabu search to a chaotic version. This chaotic method includes both effects of the chaotic dynamical search and the exponential tabu search, and exhibits better performance than the conventional and exponential tabu searches. Last, we propose an automatic parameter tuning method and show that the proposed method exhibits high performance even on large QAPs.
Źródło:
Control and Cybernetics; 2000, 29, 3; 773-788
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Determination of selected parameters in a 1D open channel flow model
Autorzy:
Weinerowska-Bords, K.
Powiązania:
https://bibliotekanauki.pl/articles/1933161.pdf
Data publikacji:
2007
Wydawca:
Politechnika Gdańska
Tematy:
determination of parameters
optimization procedures
well-posed and ill-posed problems
numerical methods
Opis:
Determination of the model's parameters is an important stage of mathematical models' application. In the case of a free-surface ID unsteady flow model defined by the de Saint- Venant equations, one of the groups of parameters to be estimated is the set of parameters describing energy losses due to friction. The parameters can be estimated in different ways, but in most cases the task of their determination is an ill-posed problem. In such cases, optimi-zation methods are the most common approach. In spite of numerous examples of such applications, these techniques are still not fully recognized, as there are several problems of different nature that require thorough analysis. Automatic optimization methods are discussed in the paper. The most important questions of choosing the objective function and the optimization algorithm are considered. Problems connected with data reliability and accessibility and their influence on the solution are discussed. The most common pitfalls of optimization applications are discussed. The analysis is supported with numerical examples.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2007, 11, 4; 341-364
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A loss function for box-constrained inverses problems
Autorzy:
Yoneda, K.
Powiązania:
https://bibliotekanauki.pl/articles/375902.pdf
Data publikacji:
2008
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
individual behavior
inverse problems
simultaneous equations
optimization
Opis:
A loss function is proposed for solving box-constrained inverse problems. Given causality mechanisms between inputs and outputs as smooth functions, an inverse problem demands to adjust the input levels to make the output levels as close as possible to the target values; box-constrained refers to the requirement that all outcome levels remain within their respective permissible intervals. A feasible solution is assumed known, which is often the status quo. We propose a loss function which avoids activation of the constraints. A practical advantage of this approach over the usual weighted least squares is that permissible outcome intervals are required in place of target importance weights, facilitating data acquisition. The proposed loss function is smooth and strictly convex with closed-form gradient and Hessian, permitting Newton family algorithms. The author has not been able to locate in the literature the Gibbs distribution corresponding to the loss function. The loss function is closely related to the generalized matching law in psychology.
Źródło:
Decision Making in Manufacturing and Services; 2008, 2, 1-2; 79-98
1896-8325
2300-7087
Pojawia się w:
Decision Making in Manufacturing and Services
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optimal design of stationary flow problems by path-following interior-point methods
Autorzy:
Antil, H.
Hoppe, R. H.
Linsenmann, C.
Powiązania:
https://bibliotekanauki.pl/articles/970290.pdf
Data publikacji:
2008
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
shape optimization
Stokes flow problems
path-following interior-point methods
Opis:
We consider the numerical solution of structural optimization problems in CFD where the state variables are supposed to satisfy a linear or nonlinear Stokes system and the design variables are subject to bilateral pointwise constraints. Within a primal-dual setting, we suggest an all-at-once approach based on interior-point methods. The discretization is taken care of by Taylor-Hood elements with respect to a simplicial triangulation of the computational domain. The efficient numerical solution of the discretized problem relies on path-following techniques, namely a continuation method with an adaptive choice of the continuation step size, a long-step path-following algorithm and a nonlinear version of Mehrotra's algorithm. The performance of the suggested methods is documented by several illustrative numerical examples.
Źródło:
Control and Cybernetics; 2008, 37, 4; 771-796
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On some new phenomena in state-constrained optimal control if ODEs as well as PDEs are involved
Autorzy:
Pesch, H. J.
Rund, A.
Wahl, V.
Wendl, S.
Powiązania:
https://bibliotekanauki.pl/articles/969885.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
optimal control of partial differential equations
ODE-PDE-constrained optimization
state constraints
non-local state-constraints
integro-state constraints
optimal control problems for integro-differential equations
jump conditions
Opis:
In this paper we investigate a new class of optimal control problems with ODE as well as PDE constraints. We would like to call them "hypersonic rocket car problems", since they were inspired, on the one hand, by the well known rocket car problem from the early days of ODE optimal control, on the other hand by a recently investigated flight path trajectory optimization problem for a hypersonic aircraft. The hypersonic rocket car problems mimic the latter's coupling structure, yet in a strongly simplified form. They can therefore be seen as prototypes of ODE-PDE control problems. Due to their relative simplicity they allow to a certain degree to obtain analytical solutions and insights into the structure of the adjoints, which would currently be unthinkable with complex real life problems. Our main aim is to derive and verify the necessary optimality conditions. Most of the obtained results bear a lot of similarities with state constrained ODE optimal control problems, yet we also observed some new phenomena.
Źródło:
Control and Cybernetics; 2010, 39, 3; 647-660
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A manufacturing network for generating added value from a geographical distance for the next generation
Autorzy:
Yukawa, K.
Kawakami, T.
Powiązania:
https://bibliotekanauki.pl/articles/99988.pdf
Data publikacji:
2011
Wydawca:
Wrocławska Rada Federacji Stowarzyszeń Naukowo-Technicznych
Tematy:
virtual concentration
optimization problems
value-added network
Opis:
n this study, we suggested a manufacturing network for generating added value from a geographical distance in terms of value creation from various management resources. Until today, most researchers focused on the Real Concentration of Production Base, which provides certain manufacturing benefits in these domains. However, "the Virtual Concentration of Production Bases" is realized by overcoming large physical distances and time differences between production bases, and creates greater added value for products. We attempted the simulation of the manufacturing network of creating the added value after having shown the new framework of network analysis in the manufacturing system.
Źródło:
Journal of Machine Engineering; 2011, 11, 3; 44-57
1895-7595
2391-8071
Pojawia się w:
Journal of Machine Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Sensitivity analysis for state constrained optimal control problems
Autorzy:
Malanowski, K.
Powiązania:
https://bibliotekanauki.pl/articles/206110.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
sensitivity analysis
cone-constrained optimization problems
nonlinear optimal control
first order state constraints
Opis:
A sensitivity result for cone-constrained optimization problem in abstract Hilbert spaces is obtained, using a slight modification of Haraux's theorem on differentiability of the metric projection onto polyhedric sets. This result is applied to sensitivity analysis for nonlinear optimal control problems subject to first order state constraints.
Źródło:
Control and Cybernetics; 2011, 40, 4; 1043-1058
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Multiobjective shape optimization of selected coupled problems by means of evolutionary algorithms
Autorzy:
Długosz, A.
Burczyński, T.
Powiązania:
https://bibliotekanauki.pl/articles/202348.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
multiobjective optimization
evolutionary algorithms
multiphysics
coupled field problems
finite element method
Opis:
In present paper an improved multi-objective evolutionary algorithm is used for Pareto optimization of selected coupled problems. Coupling of mechanical, electrical and thermal fields is considered. Boundary-value problems of the thermo-elasticity, piezoelectricity and electro-thermo-elasticity are solved by means of finite element method (FEM). Ansys Multiphysics and MSC.Mentat/Marc software are used to solve considered coupled problems. Suitable interfaces between optimization tool and the FEM software are created. Different types of functionals are formulated on the basis of results obtained from the coupled field analysis. Functionals depending on the area or volume of the structure are also proposed. Parametric curves NURBS are used to model some optimized structures. Numerical examples for exemplary three-objective optimization are presented in the paper.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2012, 60, 2; 215-222
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Solving Markov decision processes by d-graph algorithms
Autorzy:
Kátai, Z.
Powiązania:
https://bibliotekanauki.pl/articles/205688.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
Markov decision processes
dynamic programming
graph representation
graph algorithms
optimization problems
Opis:
Markov decision processes (MDPs) provide a mathematical model for sequential decisionmaking (sMDP/dMDP: stochastic/ deterministic MDP). We introduce the concept of generalized dMDP (g-dMDP) where each action may result in more than one next (parallel or clone) state. The common tools to represent dMDPs are digraphs, but these are inadequate for sMDPs and g-dMDPs. We introduce d-graphs as general tools to represent all the above mentioned processes (stationary versions). We also present a combined d-graph algorithm that implements dynamic programming strategies to find optimal policies for the finite/infinite horizon versions of these Markov processes. (The preliminary version of this paper was presented at the Conference MACRo 2011.)
Źródło:
Control and Cybernetics; 2012, 41, 3; 577-593
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Utility Function to Solve Approximate Linear Equations for Decision Making
Autorzy:
Yoneda, K.
Celaschi, W.
Powiązania:
https://bibliotekanauki.pl/articles/375878.pdf
Data publikacji:
2013
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
individual behavior
inverse problems
simultaneous equations
optimization
Opis:
Suppose there are a number of decision variables linearly related to a set of outcome variables. There are at least as many outcome variables as the number of decision variables since all decisions are outcomes by themselves. The quality of outcome is evaluated by a utility function. Given desired values for all outcome variables, decision making reduces to “solving” the system of linear equations with respect to the decision variables; the solution being defined as decision variable values such that maximize the utility function. This paper proposes a family of additively separable utility functions which can be defined by setting four intuitive parameters for each outcome variable: the desired value of the outcome, the lower and the upper limits of its admissible interval, and its importance weight. The utility function takes a nonnegative value within the admissible domain and negative outside; permits gradient methods for maximization; is designed to have a small dynamic range for numerical computation. Small examples are presented to illustrate the proposed method.
Źródło:
Decision Making in Manufacturing and Services; 2013, 7, 1-2; 5-18
1896-8325
2300-7087
Pojawia się w:
Decision Making in Manufacturing and Services
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Reconstruction of delivery positions in the city of Celje, Slovenia
Wiederaufbau von dem lieferposition in stadt Celje, Slowenien
Autorzy:
Dragan, D.
Vizinger, T.
Intihar, M.
Kramberger, B.
Fosner, M.
Prah, K.
Powiązania:
https://bibliotekanauki.pl/articles/374228.pdf
Data publikacji:
2013
Wydawca:
Politechnika Śląska. Wydawnictwo Politechniki Śląskiej
Tematy:
location problems
maximal covering problems
optimization
simulation
GIS
urban freight transport
problemy lokalizacji
optymalizacja
symulacja
miejski transport towarowy
Opis:
The paper addresses the problem of the reconstruction and allocation of delivery positions in the urban area. The aim is to achieve the optimal reorganization of urban freight transport in old town core in the municipality of Celje. Optimal allocation relies on optimization based on the Monte Carlo simulation and represents a first stage of a two-stage optimization approach to re-design the existing urban freight transport. The number of optimal delivery positions is required to be as minimal as possible, which can still assure a maximal service area within the prescribed radius, while keeping the minimal walking distances of delivery personnel between the nearest delivery position and the customer’s physical location. The main issues of the used heuristic allocation algorithm and the presentation of calculated results are provided. In the near future, the calculated delivery positions are going to be used for the purpose of physical implementation in order to improve the existing delivery transport.
Der Artikel behandelt das Problem der Wiederaufbau und Allokation von den Lieferung Positionen in einem städtischen Gebiet. Der Zweck ist die optimale Reorganisation des städtischen Güterverkehrs im alten Stadtkern in der Gemeinde Celje zu Erreichen. Die optimale Allokation basiert auf der Optimierung auf Basis der Monte-Carlo-Simulationen und stellt die erste Stufe einer zweistufigen Optimierung Verfahren zur Re-Designs der bestehenden städtischen Güterverkehrs. Die Anzahl der optimalen Lieferpositionen sollte so wenig wie möglich sein, aber trotzdem einen maximalen Service-Bereich innerhalb des vorgeschriebenen Radius gewährleisten. Gleichzeitig sollte die Entfernung zwischen den nächstgelegenen Lieferpositionen und Kunden Positionen kleinstmöglich sein. Die wichtigsten Themen des verwendeten Heuristic Zuordnungsalgorithmus und die Darstellung der berechneten Ergebnisse sind gegeben. Die Standorte der berechneten Lieferung Positionen werden zum Zwecke der physikalischen Implementierung genutzt, um den bestehenden Güterverkehr zu verbessern
Źródło:
Transport Problems; 2013, 8, 2; 11-23
1896-0596
2300-861X
Pojawia się w:
Transport Problems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Solving Delivery Problems in Distribution Systems
Autorzy:
Michlowicz, Edward
Powiązania:
https://bibliotekanauki.pl/articles/504345.pdf
Data publikacji:
2013
Wydawca:
Międzynarodowa Wyższa Szkoła Logistyki i Transportu
Tematy:
optimization
transport tasks
delivery problems
Opis:
The subject matter of this article is the optimization of delivery problems (Vehicle Routing Problems – VRP) with regard to distribution systems. These issues belong to the class of NP-hard problems. Current solutions to various delivery problems (VRP, TSP, MTSP, VRPTW, RDPTW) were analysed. Two examples were presented. In a transport and production task, a marginal cost equalling (MCE) algorithm was used. In the case of a Multi Depot Vehicle Routing Problem (MDVRP), an evolutionary algorithm was used.
Źródło:
Logistics and Transport; 2013, 18, 2; 33-40
1734-2015
Pojawia się w:
Logistics and Transport
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 37

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