The paper presents the measurement results of the noise level of a power transformer. The noise sources occurring in the transformer are presented, and the method applied and the measuring tools used are characterized...
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ISBN:
(纸本)9781627480000
The paper presents the measurement results of the noise level of a power transformer. The noise sources occurring in the transformer are presented, and the method applied and the measuring tools used are characterized. The measurements were taken in 29 points located around the transformer. The evaluation of noise was carried out based on the revised coefficient of the acoustic pressure level. The research work results presented enable the evaluation of the influence of the noise of the unit under study on its environment and make it easier to diagnose the degrees of wear of the fans installed in transformer coolers.
The paper presents research results of electrokinetic zeta potential that exists in the electrical double layer on the border of the solid and liquid phases. For zeta potential examination, samples in the colloid form...
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The paper presents research results of electrokinetic zeta potential that exists in the electrical double layer on the border of the solid and liquid phases. For zeta potential examination, samples in the colloid form were used, the continuous (dispersing) phase of which was constituted by dielectric liquid mixtures formed on the base of simple hydrocarbons (hexane, cyclohexane, toluene), and the solid (dispersed) phase was constituted by materials in a disintegrated form (aluminum, copper, steatite, Al-70). The measurements were taken with Zetasizer 2000 - by Malvern Instruments (UK). Volume density of charge qw on the border of the solid and liquid phases, responsible for generation of electrostatic charges, was determined based on the measured zeta potential and physicochemical properties of the liquids under study.
The paper will present the wavelet analysis results using continuous and discrete wavelet transforms of vibrations of a power transformer tub installed on the block of a conventional, thermal condensation power statio...
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ISBN:
(纸本)9781627480000
The paper will present the wavelet analysis results using continuous and discrete wavelet transforms of vibrations of a power transformer tub installed on the block of a conventional, thermal condensation power station. The research tests were carried out during a regular transformer operation in industrial conditions. The measurements were taken from the point of view of the evaluation of the influence of the vibrations registered on the analysis results of the acoustic emission signals generated by partial discharges that can occur in paper-oil insulation systems of power transformers. Moreover, the analyses carried out were supplemented with the research results obtained in laboratory conditions during the measurements taken in the high-voltage testing station of high-voltage power appliances. The influence of the loosened screws fastening the lid of the transformer tub on the time-frequency analysis results obtained of the vibrations registered was investigated. Moreover, the range of the research work carried out referred to the evaluation of the influence of the changes of the pressure force of the metal plates forming the transformer core on the vibration measurement results were obtained. In summary, the evaluation of usefulness was presented and the range of the time-frequency analysis application possibilities, and especially wavelet transforms, in diagnostics of power transformers using the acoustic methods was characterized.
The paper deals with the calculation of hysteresis power loss in cores of electromechanical converters. The analysis was carried out using the Jiles-Atherton model of ferromagnetic hysteresis incorporated into two-dim...
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The paper deals with the calculation of hysteresis power loss in cores of electromechanical converters. The analysis was carried out using the Jiles-Atherton model of ferromagnetic hysteresis incorporated into two-dimensional time-stepping finite element model. A vector hysteresis model was constructed by the vectorisation of a scalar model. The total power loss due to hysteresis was split into two component, one originating from the purely alternating magnetic field, and the second being a consequence of the local predomination of vector nature of magnetic field distribution. Two computational examples are presented showing the general applicability of the algorithm for determination of power loss distribution.
This paper presents an analysis how the pulses in the long three-conductor coupled lines with common screen interact mutually. The interaction of pulses appears in those places of the line, where there is a change in ...
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This paper presents an analysis how the pulses in the long three-conductor coupled lines with common screen interact mutually. The interaction of pulses appears in those places of the line, where there is a change in characteristic impedance causing a change in reflection coefficient for pulses moving along the line. An exemplary analysis is conducted for a homogenous lossless line both at its starting and terminal point. The results of the analysis are analytical expressions describing quantitative interactions of pulses. The expressions are verified numerically and experimentally involving measurements of the real-life line. The mutual interaction of pulses can be useful in location of faults in electric power lines by means of the pulses method.
Three-dimensional (3D) segmentation has become an essential part of volumetric image analysis. The methodology is based on the Live-Wire approach implemented in two-dimensional (2D) scene, yet two significant modifica...
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Three-dimensional (3D) segmentation has become an essential part of volumetric image analysis. The methodology is based on the Live-Wire approach implemented in two-dimensional (2D) scene, yet two significant modifications have been employed. The wavelet-based cost map has improved the segmentation accuracy, whereas the Fuzzy C-Means (FCM) clustering procedure has shrunk the area to be searched, and thus has lower the numerical complexity. The 3D segmentation has been obtained by implementing the FCM clustering procedure with morphological operations. It does not require users interaction. The method has been employed to Magnetic Resonance Imaging (MRI) and X-Ray Computed Tomography (CT) studies. Additionally, noise resistance of the 3D approach has been measured.
In this paper a method to estimate the initial rotor position of the switched reluctance motor (SRM) at the stand still condition is proposed. The proposed method can be implemented by the simple microcontroller based...
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ISBN:
(纸本)8986510081
In this paper a method to estimate the initial rotor position of the switched reluctance motor (SRM) at the stand still condition is proposed. The proposed method can be implemented by the simple microcontroller based system, and it is not necessary to know the magnetization curves. The impulse gate drive signal is applied and the winding current is detected and its approximate value is used for calculating the rotor position. The compensation method to reduce the estimation error thorough one cycle is also mentioned. The proposed method is implemented with the 6-stator-pole and 4-rotor-pole, 1.5 kW 3-phase switched reluctance motor.
In this paper, a design of the 3-phase, 6-stator-pole and 4-rotor-pole, 15 kW switched reluctance motor for the propulsion system of the electric vehicle is presented. Its performance such as the torque per volume and...
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ISBN:
(纸本)8986510081
In this paper, a design of the 3-phase, 6-stator-pole and 4-rotor-pole, 15 kW switched reluctance motor for the propulsion system of the electric vehicle is presented. Its performance such as the torque per volume and its efficiency are compared to the machine which is designed based on the conventional design guideline.
Fuzzy c-means method (FCM) is a popular tool for a fuzzy data processing. In the current study, a FCM-based method of fuzzy clustering in a kernel space has been implemented. First, a "kernel trick" is appli...
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Fuzzy c-means method (FCM) is a popular tool for a fuzzy data processing. In the current study, a FCM-based method of fuzzy clustering in a kernel space has been implemented. First, a "kernel trick" is applied to the fuzzy c-means algorithm. Then, the new method is employed for a fast automated segmentation of demyelination plaques in Multiple Sclerosis (MS). The clusters in a Gaussian kernel space are analysed in the histogram context and used during the initial classification of the brain tissue. Received classification masks are then used to detect the region of interest, eliminate false positives and label MS lesions.
The rapid changes, that are induced continuously by the ICT, are going to transform gradually the Information Society into the Knowledge Based Society. It is the time of paradigms convergence like Concurrent Enterpris...
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