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Wyświetlanie 1-15 z 17
Tytuł:
Bin packing with restricted item fragmentation
Autorzy:
Pieńkosz, K.
Powiązania:
https://bibliotekanauki.pl/articles/205659.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
bin packing
fragmentable items
approximation algorithms
Opis:
In this paper we consider a generalization of the bin packing problem, in which it is permitted to fragment the items while packing them into bins. There is, however, a restriction that the size of each piece of the fragmented item cannot be smaller than a given parameter β An interesting aspect of such a model is that if β= 0, then the problem can be easily solved optimally. If β is large enough, meaning, in fact, that the fragmentation is not allowed, we get the classical bin packing problem, which is NP-hard in the strong sense. We present approximation algorithms for solving the problem and analyse their properties. The results of computational experiments and conclusions relating to the effectiveness of the algorithms are also presented.
Źródło:
Control and Cybernetics; 2014, 43, 4; 547-556
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optimality conditions for a set-valued optimization problem in terms of approximations
Autorzy:
Gadhi, Nazih Abderrazzak
Rahou, Fatima Zahra
El Idrissi, Mohammed
Powiązania:
https://bibliotekanauki.pl/articles/1839139.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
approximation
weak Paretominimal point
A-pseudo-convexity
A-quasi-invexity
Opis:
In this paper, we are concerned with a constrained set-valued optimization problem (P). Using support functions, we give necessary optimality conditions in terms of Karush-Kuhn-Tucker (KKT) multipliers and approximations. Under generalized convex- ity, we investigate sufficient optimality conditions. An example illustrating our findings is also given.
Źródło:
Control and Cybernetics; 2019, 48, 3; 439-452
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stability analysis of variational inequalities for bang-singular-bang controls
Autorzy:
Felgenhauer, U.
Powiązania:
https://bibliotekanauki.pl/articles/206215.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
parametric optimal control problems bang-singular control structure
approximation of extremals
Opis:
The paper is related to parameter dependent optimal control problems for control-affine systems. The case of scalar reference control with bang-singular-bang structure is considered. The analysis starts from a variational inequality (VI) formulation of Pontryagin’s Maximum Principle. In a first step, under appropriate higher-order sufficient optimality conditions, the existence of solutions for the linearized problem (LVI) is proven. In a second step, for a certain class of right-hand side perturbation, it is show that the controls from LVI have bang-singular-bang structure and, in L1 topology, depend Lipschitz continuously on the data. Applying finally a common fixed-point approach to VI, the results are brought together to obtain existence and structural stability results for extremals of the original control problem under parameter perturbation.
Źródło:
Control and Cybernetics; 2013, 42, 3; 557-592
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Toward interactive rough-granular computing
Autorzy:
Skowron, A.
Wasilewski, P.
Powiązania:
https://bibliotekanauki.pl/articles/206358.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
rough sets
granular computing
interactive computations
perception based computing
perception attributes
sensory attributes
action attributes
vague concepts
approximation of complex vague concepts
ontology approximation
Opis:
Computations in Rough-Granular Computing (RGC) are performed on (information) granules. The rough set approach is used in RGC for inducing granules approximating other granules about which imperfect knowledge is given only. For modeling of complex systems, it is important to extend the RGC approach to Interactive Rough-Granular Computing (IRGC) based on interactions of granules. In this paper, we discuss some fundamental issues for interaction of granules such as general scheme of interactions and the role of dynamic attributes and dynamic information systems in modeling interactive computations.
Źródło:
Control and Cybernetics; 2011, 40, 2; 213-235
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparison of linear interpolation and arctan approximation of one-dimensional monotonic utility functions based on experimental data
Autorzy:
Nikolova, N.
Tenekedjiev, K.
Dong, F.
Hirota, K.
Powiązania:
https://bibliotekanauki.pl/articles/969632.pdf
Data publikacji:
2009
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
utility function
interpolation
approximation
weighted least square
goodness-of-fit
statistical tests
Opis:
Elicitation of utilities is among the most time consuming tasks in decision analysis. We search for ways to shorten this phase without compromising the quality of results. We use the results from an empirical experiment with 104 participants. They elicited 9 inner nodes from their one-dimensional utility function over monetary gains and losses using three elicitation techniques. A specific feature of the results is their interval character, as the elicitators are fuzzy rational individuals. The data is used to construct arctan-approximated and linearly interpolated utilities and to compare the results. We form partial samples with 3, 4 and 5 nodes for each participant and each elicitation method, and again interpolate/approximate the utilities. We introduce goodness-of-fit and deterioration measures to analyze the decrease in quality of the utility function due to reduced data nodes. The analysis, using paired-sample tests, leads to the following conclusions: 1) arctan-approximation is more adequate than linear interpolation over the whole samples; 2) 5 inner nodes are sufficient to construct a satisfactory arctan-approximation; 3) arctan-approximation and linear interpolation are almost equal in quality over the partial samples, but the local risk aversion of the linearly interpolated utility function is of poor quality unlike that of the arctan-approximated utility function.
Źródło:
Control and Cybernetics; 2009, 38, 3; 835-861
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On optimal and quasi-optimal controls in coefficients for multi-dimensional thermistor problem with mixed Dirichlet-Neumann boundary conditions
Autorzy:
Kogut, Peter I.
Powiązania:
https://bibliotekanauki.pl/articles/970117.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
nonlinear elliptic equations
control in coefficients
p(x)-Laplacian
approximation approach
thermistor problem
Opis:
In this paper we deal with an optimal control problem in coefficients for the system of two coupled elliptic equations, also known as the thermistor problem, which provides a simultaneous description of the electric field u = u(x) and temperature θ(x). The coefficients of the operator div (B(x)∇θ(x)) are used as the controls in L∞(Ω). The optimal control problem is to minimize the discrepancy between a given distribution θd ∈ Lr(Ω) and the temperature of thermistor θ ∈ W1,γ 0 (Ω) by choosing an appropriate anisotropic heat conductivity matrix B. Basing on the perturbation theory of extremal problems and the concept of fictitious controls, we propose an “approximation approach” and discuss the existence of the so-called quasi-optimal and optimal solutions to the given problem.
Źródło:
Control and Cybernetics; 2019, 48, 1; 31-68
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Neuro-fuzzy TSK network for approximation of static and dynamic functions
Autorzy:
Linh, T.
Osowski, S.
Powiązania:
https://bibliotekanauki.pl/articles/205951.pdf
Data publikacji:
2002
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
algorytm uczenia się
aproksymacja
sieć neuronowo-rozmyta
approximation
learning algorithms
neuro-fuzzy networks
Opis:
The paper presents the neuro-fuzzy network in application to the approximation of the static and dynamic functions. The network implements the Takagi-Sugeno inference rules. The learning algorithm is based on the hybrid approach, splitting the learning phase into two stages : the adaptation of the linear output weights using the SVD algorithm and the conventional steepest descent backpropagation rule in application to the adaptation of the nonlinear parameters of the membership functions. The new approach to the generation of the inference rules, based on the fuzzy self-organization is proposed and the algorithm of automatic determination of the number of these rules has been also implemented. The method has been applied for the off-line modelling of static nonlinear relations and on-line simulation of the dynamic systems.
Źródło:
Control and Cybernetics; 2002, 31, 2; 309-326
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Metric regularity under approximations
Autorzy:
Dontchev, A. L.
Veliov, V. M.
Powiązania:
https://bibliotekanauki.pl/articles/970750.pdf
Data publikacji:
2009
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
metric regularity
inexact iterative methods
Newton method
proximal point method
discrete approximation
optimal control
Opis:
In this paper we show that metric regularity and strong metric regularity of a set-valued mapping imply convergence of inexact iterative methods for solving a generalized equation associated with this mapping. To accomplish this, we first focus on the question how these properties are preserved under changes of the mapping and the reference point. As an application, we consider discrete approximations in optimal control.
Źródło:
Control and Cybernetics; 2009, 38, 4B; 1283-1303
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dynamic Programming: an overview
Autorzy:
Sniedovich, M.
Powiązania:
https://bibliotekanauki.pl/articles/205819.pdf
Data publikacji:
2006
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
programowanie dynamiczne
dynamic programming
principle of optimality
curse of dimensionality
successive approximation
push
pull
Opis:
Dynamic programing is one of the major problem-solving methodologies in a number of disciplines such as operations research and computer science. It is also a very important and powerful tool of thought. But not all is well on the dynamic programming front. There is definitely lack of commercial software support and the situation in the classroom is not as good as it should be. In this paper we take a bird's view of dynamic programming so as to identify ways to make it more accessible to students, academics and practitioners alike.
Źródło:
Control and Cybernetics; 2006, 35, 3; 513-533
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A method of approximating Pareto sets for assessments of implicit Pareto set elements
Autorzy:
Kaliszewski, I.
Powiązania:
https://bibliotekanauki.pl/articles/970402.pdf
Data publikacji:
2007
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
multiple criteria decision making
bi-criteria problems
Pareto set
efficiency
convex function approximation
sandwich algorithms
Opis:
Deriving efficient variants in complex multiple criteria decision making problems requires optimization. This hampers greatly broad use of any multiple criteria decision making method. In multiple criteria decision making Pareto sets, i.e. sets of efficient vectors of criteria values corresponding to feasible decision alternatives, are of primal interest. Recently, methods have been proposed to calculate assessments for any implicit element of a Pareto set (i.e. element which has not been derived explicitly but has been designated in a form which allows its explicit derivation, if required) when a finite representation of the Pareto set is known. In that case calculating respective bounds involves only elementary operations on numbers and does not require optimization. In this paper the problem of approximating Pareto sets by finite representations which assure required tightness of bounds is considered for bicriteria decision making problems. Properties of a procedure to derive such representations and its numerical behavior are investigated.
Źródło:
Control and Cybernetics; 2007, 36, 2; 367-381
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Error estimates for the finite-element approximation of an elliptic control problem with pointwise state and control constraints
Autorzy:
Meyer, C.
Powiązania:
https://bibliotekanauki.pl/articles/971011.pdf
Data publikacji:
2008
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
równanie eliptyczne
aproksymacja numeryczna
linear quadratic optimal control problems
elliptic equations
state constraints
numerical approximation
Opis:
We consider a linear-quadratic elliptic optimal control problem with pointwise state constraints. The problem is fully discretized using linear ansatz functions for state and control. Based on a Slater-type argument, we investigate the approximation behavior for mesh size tending to zero. The obtained convergence order for the L²-error of the control and for H 1-error of the state is 1 - ε in the two-dimensional case and 1/2 - ε in three dimensions, provided that the domain satisfies certain regularity assumptions. In a second step, a state-constrained problem with additional control constraints is considered. Here, the control is discretized by constant ansatz functions. It is shown that the convergence theory can be adapted to this case yielding the same order of convergence. The theoretical findings are confirmed by numerical examples.
Źródło:
Control and Cybernetics; 2008, 37, 1; 51-83
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Similarity-based methods : a general framework for classification, approximation and association
Autorzy:
Duch, W.
Powiązania:
https://bibliotekanauki.pl/articles/206007.pdf
Data publikacji:
2000
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
aproksymacja
klasyfikacja
optymalizacja
pamięć asocjacyjna
approximation
associative memory
classification
feature selection
kNN
optimization
similarity-based methods
Opis:
Similarity-based methods (SBM) are a generalization of the minimal distance (MD) methods which form a basis of several machine learning and pattern recognition methods. Investigation of similarity leads to a fruitful framework in which many classification, approximation and association methods are accommodated. Probability p(C|X; M) of assigning class C to a vector X, given a classification model M, depends on adaptive parameters and procedures used in construction of the model. Systematic overview of choices available for model building is presented and numerous improvements suggested. Similarity-Based Methods have natural neural-network type realizations. Such neural network models as the Radial Basis Functions (RBF) and the Multilayer Perceptrons (MLPs) are included in this framework as special cases. SBM may also include several different submodels and a procedure to combine their results. Many new versions of similarity-based methods are derived from this framework. A search in the space of all methods belonging to the SBM framework finds a particular combination of parameterizations and procedures that is most appropriate for a given data. No single classification method can beat this approach. Preliminary implementation of SBM elements tested on a real-world datasets gave very good results.
Źródło:
Control and Cybernetics; 2000, 29, 4; 937-967
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Controllability of a time-discrete dynamical system with the aid of the solution of an approximation problem
Sterowalność układu dynamicznego z czasem dyskretnym z zastosowaniem zadania aproksymującego
Autorzy:
Krabs, W.
Picki, S.
Powiązania:
https://bibliotekanauki.pl/articles/206703.pdf
Data publikacji:
2003
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
zadanie sterowania optymalnego z czasem dyskretnym
zadanie aproksymacji
sterowalność
time-discrete optimal control problems
approximation problem
controllability
Opis:
The paper is concerned with time-discrete dynamical systems, whose dynamics is described by a system of vector difference equations involving state and control vector functions. It is assumed that that the uncontrolled system (in which the control vectors are put to zero) admits steady states. The aim is to reach such a steady state by a suitable choice of control functions within finitely many time-steps starting with an initial state at time zero. We first give sufficient conditions for the solvability of this problem of controllability. Then, we develop a stepwise game-theoretical method for its solution. In the cooperative case this method can be combined with the solution of a suitable approximation problem and thereby lead to a solution of the problem of controllability within the smallest number of time steps, if the problem is solvable. Finally, we present a stepwise non-cooperative game theoretical solution.
Artykuł dotyczy układów dynamicznych dyskretnych w czasie, których dynamika jest opisywana przy pomocy wektorowych równań różnicowych z wektorowymi funkcjami stanu i sterowania. Zakłada się, że układ nie sterowany (w którym wektory sterowań są równe zeru) przyjmuje stany ustalone. Celem jest osiągnięcie takiego stanu ustalonego poprzez odpowiedni dobór funkcji sterowania w skończonej liczbie kroków w czasie, startując z pewnego stanu w momencie zerowym. Najpierw podano warunki wystarczające rozwiązywalności tego zadania sterowalności. Następnie, przedstawiono metodę iteracyjną opartą na teorii gier do znajdywania rozwiązania. W przypadku gry kooperacyjnej metoda ta może być połączona z rozwiązaniem odpowiedniego zadania aproksymacji i w ten sposób prowadzić do rozwiązania zagadnienia sterowalności w najmniejszej liczbie kroków w czasie, jeśli zadanie ma rozwiązanie. Na koniec przedstawiono sposób rozwiązania krokowego dla przypadku gry nie-kooperacyjnej.
Źródło:
Control and Cybernetics; 2003, 32, 1; 57-74
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Finite element error analysis for state-constrained optimal control of the Stokes equations
Autorzy:
Los Reyes, J. C. de
Meyer, C.
Vexler, B.
Powiązania:
https://bibliotekanauki.pl/articles/969607.pdf
Data publikacji:
2008
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
równanie Stokesa
aproksymacja numeryczna
element skończony
linear quadratic optimal control problems
Stokes equations
state constraints
numerical approximation
finite elements
Opis:
An optimal control problem for 2d and 3d Stokes equations is investigated with pointwise inequality constraints on the state and the control. The paper is concerned with the full discretization of the control problem allowing for different types of discretization of both the control and the state. For instance, piecewise linear and continuous approximations of the control are included in the present theory. Under certain assumptions on the L∞-error of the finite element discretization of the state, error estimates for the control are derived which can be seen to be optimal since their order of convergence coincides with the one of the interpolation error. The assumptions of the L∞-finite-eleinent-error can be verified for different numerical settings. Finally the results of two numerical experiments are presented.
Źródło:
Control and Cybernetics; 2008, 37, 2; 251-284
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dijkstras algorithm revisited: the dynamic programming connexion
Autorzy:
Sniedovich, M.
Powiązania:
https://bibliotekanauki.pl/articles/970872.pdf
Data publikacji:
2006
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
programowanie dynamiczne
badania operacyjne
Dijkstra's algorithm
dynamic programming
greedy algorithm
principle of optimality
successive approximation
operations research
computer science
Opis:
Dijkstra's Algorithm is one of the most popular algorithms in computer science. It is also popular in operations research. It is generally viewed and presented as a greedy algorithm. In this paper we attempt to change this perception by providing a dynamic programming perspective on the algorithm. In particular, we are reminded that this famous algorithm is strongly inspired by Bellman's Principle of Optimality and that both conceptually and technically it constitutes a dynamic programming successive approximation procedure par excellence. One of the immediate implications of this perspective is that this popular algorithm can be incorporated in the dynamic programming syllabus and in turn dynamic programming should be (at least) alluded to in a proper exposition/teaching of the algorithm.
Źródło:
Control and Cybernetics; 2006, 35, 3; 599-620
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 17

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