Subject matter of this paper applies to improvement of acoustic emission method used in the diagnosis of on load tap changers of high power transformers. During measurement of acoustic emission signals generated by da...
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Subject matter of this paper applies to improvement of acoustic emission method used in the diagnosis of on load tap changers of high power transformers. During measurement of acoustic emission signals generated by damages or defects, which can appear in insulation system and in the power transformer tap changers, various forms of noise signals may occur. Interferences occurring during measurements under laboratory and under industrial conditions can be generated either by sources placed inside the studied electric power device or they can be emitted in their immediate vicinity. Sources of interfering signals are physical phenomena of a mechanical, electrical or acoustical nature. Interferences appearing during measurement of acoustic emission pulses generated by electrical discharges and other types of defects that overlap the measured waveforms may result in their distortion. As part of the research conducted, the results of which are presented in this paper, following was subjected under consideration: measurements of acoustic noise signals generated by partial surface discharges occurring on support and bushing insulators were performed.
The subject matter of this article concerns the diagnostic test results of transformer cores by measuring and analysing vibroacoustic signals registered during their normal operation. The main objective of this resear...
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The subject matter of this article concerns the diagnostic test results of transformer cores by measuring and analysing vibroacoustic signals registered during their normal operation. The main objective of this research study conducted by the authors, the results of which are published in this paper, is a critical analysis of vibroacoustic criteria, which are adopted in Poland nowadays, and based on which, the assessment of the core technical condition is performed. This article presents exemplary results that were obtained on two twin units of type TET 8509 with a power of 40 MVA. The paper species diagnosed structures, the measurement system applied, and the currently used methodology to assess the degree of core loosening. To determine the efficacy and assessment accuracy of the applied vibroacoustic criteria, correlation between mechanical vibration measurements of the tested transformer tanks and results obtained by gas chromatography was performed.
Subject of the paper concerns determination of the feasibility and indication of the application scope of optical spectroscopy methods in the diagnosis of high-voltage insulators. Results of measurements of optical ra...
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Subject of the paper concerns determination of the feasibility and indication of the application scope of optical spectroscopy methods in the diagnosis of high-voltage insulators. Results of measurements of optical radiation emitted by partial and complete electrical discharges occurring on a support insulator model placed in air are presented in the paper. Registration was performed using a spectrophotometer, enabling for measurement of optical radiation in the range from 200 to 1800 nm. The primary objective of the laboratory tests was to evaluate the impact of supply voltage changes in the range from 0 to 60 kV on the intensity and spectral character of the optical radiation emitted by electric discharges generated on the porcelain insulation surface of the support insulator. In the scope of studies analyzes of the eects of voltage changes on the obtained spectral wave forms were performed, whereby voltage increase and reduction was examined separately. Additionally, measurements and analyzes carried out included impact estimation of the time period as the voltage was applied to the high-voltage electrodes on the course of optical phenomena related to the generation of electrical discharges.
This paper proposes a new Matlab toolbox to simplify the task of designing robustified Model Predictive controllers under both unstructured and structured uncertainties. With a user-friendly design, the toolbox offers...
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Purpose - This paper aims to improve the mathematical justification of certain analog signal theory concepts and offer a rigorous framework for it. Design/methodology/approach - The framework relies on functional anal...
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The paper presents a new approach to elimination of broadband noise and impulsive disturbances from archive audio recordings. The proposed adaptive Kalman-like algorithm, based on a sparse autoregressive model of the ...
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ISBN:
(纸本)9781479903573
The paper presents a new approach to elimination of broadband noise and impulsive disturbances from archive audio recordings. The proposed adaptive Kalman-like algorithm, based on a sparse autoregressive model of the audio signal, simultaneously detects noise pulses, interpolates the irrevocably distorted samples and performs signal smoothing. It is shown that bidirectional (forward-backward) processing of the archive signal improves smoothing efficiency and allows one to localize noise pulses more accurately, leading to noticeable performance improvements compared to unidirectional processing.
Articolul descrie modul în care metoda "connection pooling" optimizeazǍ accesul la baza de date. Pentru a demonstra faptul cǍ metoda într-adevǍr optimizeazǍ modul în care cerint〉ele sunt p...
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Articolul descrie modul în care metoda "connection pooling" optimizeazǍ accesul la baza de date. Pentru a demonstra faptul cǍ metoda într-adevǍr optimizeazǍ modul în care cerint〉ele sunt prelucrate, vom realiza un experiment care va cont〉ine douǍ scenarii, unul în care se foloseşte "connection pooling" şi un altul în care nu se foloseşte. La finalul experimentului, valorile obt〉inute vor demonstra cǍ accesul la baza de date este îmbunǍtǍt〉it *** studiu de caz este prezentat intr-o aplicatie cu scop medical. This paper describes how connection pooling optimizes database access. In order to prove that connection pooling really optimizes how requests are handled, we will make an experiment with two scenarios, one with connection pooling and one without this method. At the end, the values obtained will show that database access is greatly increased. A case study is presented for a medical specific application.
The problem of estimating instantaneous frequency of a nonstationary complex sinusoid (cisoid) buried in wideband noise is considered. The proposed approach extends adaptive notch filtering algorithm with a nontrivial...
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The problem of estimating instantaneous frequency of a nonstationary complex sinusoid (cisoid) buried in wideband noise is considered. The proposed approach extends adaptive notch filtering algorithm with a nontrivial performance assessment mechanism which can be used to optimize frequency tracking performance of the adaptive filter. Simulation results confirm that the proposed extension allows one to improve accuracy of frequency estimates considerably, especially in nonstationary conditions.
The concept of Low Density Parity Check (LDPC) coding over Galois Fields GF (q = 2 p ) is a generalization of the industry standard binary LDPC coding. The performance for short block length codes is significantly hig...
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The concept of Low Density Parity Check (LDPC) coding over Galois Fields GF (q = 2 p ) is a generalization of the industry standard binary LDPC coding. The performance for short block length codes is significantly higher for non-binary codes (over higher order GF fields), but on the other hand, the decoding complexity is increased. Therefore the hardware implementation of a decoder is still a challenging task. Most of the few implementations known from the literature use multiplierless computing units. In this article we present a different approach that does not exclude multiplier blocks from the decoder module. This approach is specifically intended for FPGA (Field Programmable Gate Array) implementation. We propose the decoding algorithm formulation that uses multiplications in the computation step of the Check Nodes and summations performed in the Bit Nodes. The main reason is to enable mapping a part of the algorithm to the multiplier cores available in the FPGA devices. In the article we present the decoder structure that has been developed and the construction of its building blocks. We also provide synthesis results for the Xilinx FPGAs and simulation results for a simple BPSK (Binary Phase Shift Keying) modulation model over AWGN (Additive White Gaussian Noise) channel.
The purpose of this paper is to look back on a long term informal innovative experience carried out during the last nine years until the present one, and try to discern, with a retrospective and a long time vision, wh...
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The purpose of this paper is to look back on a long term informal innovative experience carried out during the last nine years until the present one, and try to discern, with a retrospective and a long time vision, whether it has been as beneficial as expected once it has concluded. This experience has taken place in the University College of Engineering of Vitoria (Basque Country University, Spain) since the year 2.004, and it has been accomplished in the subject Company Networks of Technical Engineering in Management Computing. After the analysis of a number of data collected along these years, we found that we have reached the initial objective of increasing the enrolment in the subject that has driven the project, and other unexpected ones that are more important from a long time point of view. Once that nine years have lapsed and the project is going to be finished, we conclude that it is a very positive experience and we recommend doing the same with the new degrees of the European Higher Education Area (EHEA), as we plan.
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