Wyniki 1-5 spośród 5 dla zapytania: authorDesc:"Yuriy KOZAK"

Simplification of Optimization Process during Mathematical Models Creation

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The paper is devoted to the problem of development of mathematical macromodels creation using optimization approach. The methods of acceleration of dynamic systems macromodels creation due to separation of linear submodel and step-by-step optimization on groups of variables are considered. Streszczenie. Artykuł poświęcono problemom rozwoju matematycznych makromodeli wykorzystywanych do optymali[...]

Macromodelling of Electromechanical Systems Components

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Methods of macromodelling, which are known as methods of mathematical delineation of dynamic objects, based on information about internal dependencies between their external variables, can be defined as long-range method of scientific researches. These methods are universal and allow automation of corresponding identification procedures. Electromechanical components have their own special features connected with mechanical and electromagnetic processes combined within them, with determined types of nonlinear interdependences between variables, and with marked dispersion of time constants. In the paper a mathematical macromodel in the form of “black box" of asynchronous motor using state variables is proposed. Result of building a macromodel for AC motor of A051А4 type is q[...]

Development of Macromodels using the Evolutionary Algorithms of Optimization

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A new technique for mathematical model development based on evolutionary algorithms and optimization approach to macromodels construction has been proposed in this paper. Examples of models constructed with the use of the proposed algorithm have been presented. A comparison of new models and models created using sole optimization approach has been done. Streszczenie. Praca przedstawia nową metodę budowania makromodeli przy użyciu algorytmów ewolucyjnych optymalizacji. Proponowane podejście zostało zilustrowane przykładami konkretnych modeli, a wyniki porównane z tymi uzyskanymi przy zastosowaniu tradycyjnych deterministycznych metod optymalizacji (Budowa makromodeli z użyciem algorytmów ewolucyjnych). Keywords - mathematical model, macromodel, optimization, evolutionary algorithms Słowa kluczowe: modelowanie matematyczne, optymalizacja, algorytmy ewolucyjne Introduction At present time there is a considerable progress in construction of macromodels of electrotechnical components designed for the transients’ analysis. The permanent growth of macromodel complexity leads to the necessity of the macromodel construction process automation in case it is possible. A promising approach in this direction is the usage of optimization. According to this technique the values of macromodel coefficients are found by the minimization of some goal function Q(λ). This function represents the deviation of the object behavior calculated using the model being constructed and experimental data as a function of model coefficients. By finding the point where the mentioned function reaches its minimum we will find an optimal set of the model coefficients within a selected mathematical form of the model representation. Described approach can be used for the construction of macromodels in any mathematical form, which is represented by a limited set of coefficients. Also it does not impose any restrictions on required input information except [...]

The Impact of Calculation Precision on the Process of Mathematical Model Construction with the Use of Optimization

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The usage of calculation power of GPU cards for macromodel construction based on optimization approach can lead to significant decrease of model construction time. Unfortunately, most GPU cards do not work well with double-precision calculations. In the paper the comparison of optimization process conducted using single-precision and double-precision has been done. It is shown that the reduction of computation precision to single-precision values does not worsen the precision of obtained model and the number of required iterations of optimization algorithm. Streszczenie. Wykorzystanie mocy obliczeniowej procesorów kart graficznych do budowy makromodeli matematycznych może prowadzić do skrócenia czasu obliczeń. Niestety większość procesorów wykorzystywanych jako GPU nie pracuje w podwójnej precyzji. W artykule wykazano, że redukcja dokładności obliczeń do pojedynczej precyzji nie pogarsza jakości otrzymanego modelu, ani nie zwiększa liczby iteracji algorytmu optymalizacyjnego. (Wpływ dokładności obliczeń na proces tworzenia zoptymalizowanych modeli matematycznych) Keywords: mathematical model, macromodel, optimization, calculation precision, parallelization Słowa kluczowe: model matematyczny, optymalizacja, dokładność obliczeń, zrównoleglenie obliczeń Introduction The complexity of dynamical systems being developed and analyzed is constantly increasing. Currently such systems include elements of different nature which are described by models of different types. Another problem is the complexity of mathematical models of some components included in the system being designed. All these issues result in the complexity of simulation task in terms of required computation resources. The use of macromodels in such conditions allows to replace some components or entire subsystems with the relatively simple mathematical models, and thus to significantly decrease required computation resources needed for the analysis. So for efficient usage of[...]

Discrete mathematical macromodel of electric transmission line

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In the paper the problem of development of mathematical models and macromodels of transmission lines is discussed. Mathematical discrete macromodel of single-phase transmission line in the form of state variables using a "black box" approach was developed. Description of procedure of its creation and verification of obtained results are presented. Streszczenie. W artykule przedstawiono makromodel energetycznej linii przesyłowej. Prezentowany model został zapisany w formie zmiennych stanu i dotyczy linii jednofazowej. Dodatkowo w artykule opisano proces tworzenia modelu, sposób jego walidacji wraz z kryterium poprawności, a na końcu zamieszczono wyniki.(Makromodel linii elektroenergetycznej) Keywords: mathematical model, macromodel, transmiision line, optimization Słowa kluczowe: model matematyczny, linia przesyłowa, optymalizacja Introduction Over the last decade a considerable progress in creation of mathematical models of electric systems intended for the analysis of transient and periodic processes and further prognosis of electric power equipment operation was achieved. Improvement of the modeling process in order to obtain adequate simulation results of electric systems containing single- and three phase transmission lines is an actual problem till now. Development of electric power transmission line models with a high level of adequacy using their equivalent schemes leads to their excessive complication, and as a result, there are significant difficulties during their adaptation to modern program tools intended for the transients’ analysis. If a researcher is interested only in a reaction of the modeled object, it is possible to use the principles of macromodeling. Therefore it is expedient to create macromodels of specific objects instead of their precise mathematical models. Mathematical macromodels in the form of state variables (the “black box" approach) is the best type of macromodels which can solve the [...]

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