Frequency Resolved Partial Discharges Based on Spectral Pulse Counting

A partial discharge (PD) classification methodology based counting PD pulses in the spectral domain is proposed and presented in this paper. The spectral counting data are processed using the proposed PD Spectral Pulse Counting Mapping technique (PD-SPCM), which leads to a Frequency-Resolved Partial Discharges (FRPD) map. The proposed map is then used for PD detection and classification. In this work, corona and slot FRPDs are presented in frequency bands up to 500 MHz, obtained from laboratory measurements performed using two hydro-generator stator bars. The electromagnetic signals from the PDs were captured using a patch antenna designed for this purpose and a spectral analyzer. The corona and slot PDs were chosen because one can be mistakenly classified as the other because they may present similar Phase Resolved PD (PRPD) maps and may occupy shared spectral bands. Furthermore, corona and slot PDs can occur concurrently. The obtained results show that the corona and slot PDs can be properly identified using the developed methodology, even when they occur simultaneously. This is possible because, as it is experimentally demonstrated, corona and slot PDs have appreciable levels of spectral pulse counting in particular bands of the frequency spectrum.

Express Assessment of Coal Quality using Domestic X-ray Spectral Analyzer

At-line coal quality analyzer using the method of Energy Dispersive X-ray Fluorescence analysis is described. The analysis time of one sample does not exceed 5 minutes. The analysis errors are determined and the limitations of the approach are considered.

THE CHEMICAL COMPOSITION OF THE SURFACE LAYER OF ENAMEL DEPENDING ON ITS FUNCTIONAL STATE

Objective: to study the chemical composition of the surface layer of enamel in dental caries depending on the activity of carious lesions. Material and methods. The chemical composition of the surface layer of enamel in teeth samples with arrested (n = 15) and active (n = 15) caries was studied using the high resolution SEM «Mira» by the firm «Tescan» (Czech Republic) with the micro spectral analyzer «INCA Energy 350» of the firm «Oxford Instruments Analytical» (Great Britain). Results. We have revealed reliable increases in carbon, oxygen and other light elements in the surface layer of the enamel at the area of active carious lesions in comparison with intact enamel and arrested carious lesions; significant decreases in the content of calcium, phosphorus, ratio of Ca / P coefficient for the surface layer of the enamel of active carious lesions in comparison with intact enamel and arrested carious lesions. We have revealed no reliable differences in the content of C, O, Ca, P, CI in the surface layer of intact enamel and that at the area of arrested no cavity caries.

Synthesis of Transition Metals Carbide Compounds in the Vacuum Arc Discharge Plasma

To implement the plasmochemical synthesis of transition metals (Ti, Zr, Mo, W) carbide compounds in a plasma flux of the vacuum arc the discharge carbonaceous working gas is infused. It is shown that the composition of the initial carbonaceous gas defines both the carbon output, and the nature and course of the carbide compounds formation chemical reaction. The composition analysis of the plasma flux in the course of the coating evaporation was carried out by means of the developed emissive spectral analyzer. The result shows that a considerable part of transition metals carbide phases has wide zones of homogeneity within which the change in the carbon content happens without the crystalline grid reorganization. The work reveals and analyzes the factors defining quality of the received carbide compounds (TiC, ZrC, MoC, WC) of refractory metals in a flux of metal plasma of the vacuum arc discharge.