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1

Approximation and Prediction of the Wind Speed Change Function

Klen K., Zhuikov V.

Present Problems of Power System Control

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2018

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Nr 9

35--46

EN

In the article the features of energy summation from two wind generators, located at a certain distance from each other, are considered. The method of calculating the correlation function between the wind flow speed change functions in the direction of wind distribution is presented. The formulas for describing the fluctuation components of energy at the output of the wind generator are given for two cases: when the phases of the fluctuations of the wind flow on two wind generators are the same and when the fluctuations of the wind flow are in the antiphases. It is shown that to increase the energy level that can be taken from the wind power plant it is necessary to control the phase shift between the energy fluctuations at the output of the wind generators and use the energy of the storages; and to use linear approximations to approximate the wind speed change function. Under the condition of a linear change of the internal resistance of the wind generator in time, it is advisable to introduce the wind speed change function with linear approximations. The system of orthonormal linear functions based on Walsh functions is given. A table with formulas and graphs describing the first 8 functions, which are arranged in order of increasing the number of their sign alternating on the interval of functions definition, is presented. The result of the approximation of the wind speed change function with a system of 8 linear functions based on Walsh functions is shown. Decomposition coefficients, mean-square and average relative approximation errors for such approximation are calculated. In order to find the parameters of multiple linear regression the method of least squares is applied. The regression equation in matrix form is given. An example of application of linear regression prediction method to simple functions is shown. The restoration result for wind speed change function is shown. Decomposition coefficients, mean-square and average relative approximation errors for restoration of wind speed change function with linear regression method are calculated.

2

Biomedical images enhancement based on the properties of morphological spectra

Przytulska M., Kulikowski J. L., Wierzbicka D.

Biocybernetics and Biomedical Engineering

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2015

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Vol. 35, no. 3

206--215

EN

The method enhancing distinctiveness of the micro-morphological structures, developed using the properties of morphological spectra of their monochromatic 2D images, is presented and its effects on the bone section image are statistically compared with enhancements by Sobel, Roberts and Laplace high-pass filters. Comparison of different filters based on statistical parameters of the classes of selected image details is presented. The preferable method for choosing filtering weight coefficients is described and illustrated by an example of processing an electron-microscope image of a biotechnological specimen. The applicability of this approach and possible development directions are discussed.

3

Realizacja FPGA detekcji częstotliwości rezonansowej obwodu balansującego przekształtnika wielokomórkowego ac/ac z wykorzystaniem funkcji Walsha

Stala R.

Przegląd Elektrotechniczny

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2008

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R. 84, nr 1

25-33

PL

W celu utrzymania odpowiedniej proporcji napięć na kondensatorach źródłowych wielopoziomowego wielokomórkowego przekształtnika ac/ac stosuje się obwód balansujący - szeregowy obwód RLC dołączony do wyjścia układu. Warunkiem prawidłowej pracy przekształtnika wielokomórkowego z obwodem balansującym jest dostosowanie częstotliwości impulsowania pojedynczej komórki do częstotliwości rezonansowej obwodu balansującego. W wyniku eksploatacyjnych zmian parametrów obwodu balansującego (LC) może nastąpić zmiana jego częstotliwości rezonansowej oraz impedancji falowej. W artykule omówiono wpływ zmian parametrów obwodu balansującego na pracę przekształtnika wielokomórkowego ac/ac, oraz przedstawiono zjawiska pozwalające na rozpoznanie częstotliwości rezonansowej obwodu balansującego podczas pracy układu. Zaprezentowano realizację FPGA algorytmu czasu rzeczywistego detekcji częstotliwości rezonansowej obwodu balansującego. W pracy zrealizowano analizę harmonicznych sygnału z wykorzystaniem jego rozkładu na składowe z ortonormalnego układu funkcji Walsha.

EN

In the multilevel multicell converters the flying capacitor voltages are stabilized with use of a balancing circuit - the serial RLC connected to the output of the converter. This natural balancing process is obtained by adjustment the cells' switching frequency to the resonance frequency of the balancing circuit. As a result of exploitation the parameters of the balancing circuit (LC) and its resonance frequency or characteristic impedance can change. In the paper the effect of the balancing circuit parameters variation on the multicell ac/ac converter working conditions are described. The phenomenon that enables recognition the resonance frequency of the balancing circuit under working conditions is presented. The FPGA-based realtime detection of the resonance frequency of the balancing circuit is presented. In the algorithms the ortonormal Walsh functions system is used for signals spectrum analysis.

4

Applications of Hadamard matrices

Evangelaras H., Koukouvinos C., Seberry J.

Journal of Telecommunications and Information Technology

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2003

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nr 2

3-10

EN

We present a number of applications of Hadamard matrices to signal processing, optical multiplexing, error correction coding, and design and analysis of statistics.