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Abstract

The subject of the paper is the analysis of factors determining the value of multi-entity organizations in the energy sector and their ranking according to the degree of impact on this value. For this purpose, statistical methods were used, which are best suited to determine the order of diagnostic features according to a specific criterion. The survey covered companies from the Polish energy sector, while the process itself is based on aggregated data, which represents the financial data of capital groups currently operating in the Polish energy sector. The first part of the article presents a short description of the Polish energy sector, paying particular attention to the organizational structure of the sector, i.e. companies operating on the domestic energy market. The nature of a multi-entity enterprise as a typical economic unit in the sector is described. The second part of the article describes the assumptions of multidimensional comparative analysis (MCA) as a tool for comparing multifunctional units. The MCA makes it possible to find the most important parameters or indicators having the greatest impact on the value of a multi-entity organization, i.e. a capital group. The survey covered four companies from the Polish energy sector: TAURON Polska Energia SA, ENEA SA, ENERGA SA and PGE Polska Grupa Energetyczna SA. The study with the use of MCA was conducted in three stages: - in the first stage, on the basis of information contained in the financial statements, a matrix of diagnostic features was created, describing the financial condition of the examined entity, - in the second stage, the values of diagnostic variables were normalized/unified; two methods of normalization were applied: the method of standardization and zero unitization, - in the third stage, the diagnostic variables were grouped using two methods: the model measure of Hellwig’s development and the non-standard measure of development. The results of the analysis are illustrated by tables and figures.
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Abstract

The article presents the procedure for how to establish a mathematical model of nitrogen oxides formation based on the theory of dimensional analysis. The model is based on selected physical quantities (parameters) measurable during regular operation of a heat generation plant. The objective of using dimensional analysis to describe nitrogen oxides formation is to show that between operating parameters of the combustion equipment and the NOx formation there is a significant correlation. The obtained results, which are further described in this article, have proved this fact. The obtained formula expressing nitrogen oxides formation, based on dimensional analysis, applies universally to any boiler fuelled by coal, gas or biomass. However, it is necessary to find C, m, n constants for the formula by experiment, individually for each type of boiler and used fuel. The experiment is based on on-line measurements of selected operational parameters for a given boiler, combusting a certain type of fuel with its actual moisture content and calorific value. The methodology, described in this article, helps to find relationships between the operational parameters and the formation of NOx emissions for a particular furnace. The developed mathematical model has been validated with boilers fuelled by black coal and biomass. Both the results obtained from direct measurements of NOx in both types of boilers, and the results obtained by calculation using equation based on the dimensional analysis, are in a very good accord. When burning coal, the variation between NOx expression from the model and the on-line measurements ranges between -12.23 % and + 9.92 %, and for burning biomass between -0.54 % and 0.48 %. The intention of the authors is to inform the professional community about the suitability of the dimensional analysis to describe any phenomena for which there is currently no exact mathematical formulation based on differential equations or empirical formulas. Many other examples of dimensional analysis applications in practice may be found in the work of Čarnogurská and Příhoda (2011).
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Abstract

This paper presents the concept of an innovative field-controlled axial-flux permanent-magnet (FCAFPM) machine. In order to show the working principle and features of the proposed dual-rotor with surface-mounted PM’s and iron poles, a toroidallywounded slotted single-stator FCAFPM machine is investigated and analyzed in detail, using 3-D FEAnalysis. The control range, back electromotive force (back-EMF), output and cogging torque components have been evaluated.
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