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Statystyczna ocena zagrożenia porażeniowego podczas zwarć doziemnych w stacjach elektroenergetycznych średnich napięć

Kmak Jarosław, Nowak Wiesław, Tarko Rafał

Przegląd Elektrotechniczny

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2022

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R. 98, nr 10

99--102

PL

Artykuł dotyczy oceny zagrożenia porażeniowego podczas zwarć doziemnych w stacjach elektroenergetycznych średnich napięć zasilanych z sieci o nieskutecznie uziemionym punkcie neutralnym. Podstawę tej oceny stanowią wartości napięć uziomowych, które zależą od wartości prądu zwarcia doziemnego oraz od mającej losowy charakter wartości rezystancji uziemienia stacji. W artykule zaproponowano oryginalną metodę statystycznej oceny zagrożenia porażeniowego, którą wykorzystano do analizy rzeczywistej sieci 15 kV.

EN

The article concerns the shock hazard during earth faults in medium-voltage substations supplied from networks with non-effectively earthed neutral point. The basis for the risk assessment are the values of earth voltages which depend on the value of earth fault current and on random value of substation earth resistance. This paper proposes an original method for statistical assessment of the electric shock hazard, which was used to analyze the real 15 kV network.

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Statistical Assessment of Coal Charge Effect on Metallurgical Coke Quality

Pustejovska P., Brozova S., Jursova S.

Production Engineering Archives

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2016

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Vol. 11, No. 2

15--17

EN

The paper studies coke quality. Blast furnace technique has been interested in iron ore charge; meanwhile coke was not studied because in those previous conditions seemed to be good enough. Nowadays, the requirements for blast furnace coke has risen, especially, requirements for coke reactivity [1]. The level of reactivity parameter is determined primarily by the composition and properties of coal mixtures for coking. The paper deals with a statistical analysis of the tightness and characteristics of the relationship between selected properties of coal mixture and coke reactivity. Software Statgraphic using both simple linear regression and multiple linear regressions was used for the calculations. Obtained regression equations provide a statistically significant prediction of the reactivity of coke, or its strength after reduction of CO2, and thus their subsequent management by change in composition and properties of coal mixture [2]. There were deter-mined indexes CSR/CRI for coke [3]. Fifty – four results were acquired in the experimental parts where correlation between index CRI and coal components were studied. For linear regresion the determinant was 55.0204%, between parameters CRI – Inertinit 21.5873%. For regression between CRI and coal components it was 31.03%. For multiply linear regression between CRI and 3 feedstock components determinant was 34.0691%. Final correlation has shown the decrease in final coke reactivity for higher ash, higher content of volatile combustible in coal increases the total coke reactivity and higher amount of inertinit in coal increases the reactivity. Generally, coke quality is significantly affected by coal processing, carbonization and maceral content of coal mixture.

3

Program iteracyjny obliczenia parametrów sfery oraz ich ocena statystyczna dla WMP

Filipowski R., Lechniak Z., Zawora J.

Świat Obrabiarek i Narzędzi

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2015

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R. 10, nr 5-6

20--23

PL

Sferę w przestrzeni 3D określają cztery parametry, to jest, współrzędne położenia środka sfery oznaczone (mx,my,,mz) oraz jej promień R. Na rys. przedstawiono hipotetyczną sferę oraz chmurę punktów oznaczonych przez Pi, uzyskanych podczas pomiaru sfery sondą pomiarową na WMP. Na podstawie uzyskanego ciągu punktów oblicza się w cyklu iteracyjnym, niżej przedstawionym, cztery parametry hipotetycznej sfery.

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A statistical assessment of consumers' criteria regarding organic agricultural products: the case of organic olive oil

Baourakis G., Apostolakis I.

Foundations of Computing and Decision Sciences

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1999

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Vol. 24, No. 1

21-31

EN

The socio-economic parameters of organic farn1ing in the restructuring of small to medium agricultural economies, such as that of Greece, are of significant importance. In these cases organic farn1ing seems to offer a promising alternative and profitable agricultural practice, particularly where organic olive oil is concerned. The paper aims to find, with a statistical assessment, the criteria that the consumers use in order to choose organic products and their willingness to pay in order to buy them. An overview of the Greek organic farming structure is presented and the subjects of the supply of, and demand for, organic olive oil are discussed. A market survey2 was conducted in several areas of Greece in order to record quantitative data, preferences, purchasing criteria, buying procedures and attitudes towards organic olive oil.