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Wyświetlanie 1-15 z 21
Tytuł:
Acoustic Spectra of Ultrasound Induced Cavitations in Insulating Oils
Autorzy:
Szmechta, M.
Zmarzły, D.
Boczar, T.
Lorenc, M.
Powiązania:
https://bibliotekanauki.pl/articles/1811563.pdf
Data publikacji:
2008-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.35.Ei
43.40.Le
Opis:
Acoustic emission measurement results of acoustically induced cavitation bubbles in insulating oil are presented in this paper. Spectral analysis of acquired by a broadband transducer acoustic emission signals is proposed as a diagnostic tool for estimation of aging properties of mineral insulating oils. The article describes the main parts of the designed and built measurement apparatus used for acoustic cavitation investigation in insulating oils. In this note representative results of the experimental data taken from the apparatus are shown.
Źródło:
Acta Physica Polonica A; 2008, 114, 6A; A-231-A-238
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Quantitative Analysis of Phase Trajectory as the Information about Technical Condition of the Object
Autorzy:
Majkut, L.
Powiązania:
https://bibliotekanauki.pl/articles/1490328.pdf
Data publikacji:
2012-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.40.Le
46.40.-f
Opis:
The paper aims to describe the potential use of phase trajectory for damage detection of structural components. The attractor of the examined trajectory is a static equilibrium point of the element being diagnosed. Two different damage indices are proposed to evaluate the severity of damage in the diagnosed component. The first one refers to distance between a point on a trajectory and the point which is the attractor of the trajectory. The other one relates to linearity of the Poincaré map. Effectiveness of the proposed method was evaluated on: a simple model with two degrees of freedom, data from the finite element method model of a cantilever beam with a crack, and experimental data for a cracked plate. With the proposed method, the damage can be quickly and effectively detected. By comparing the current trajectory with that from the previous diagnostic test, it is possible to establish if the nature of crack is either propagating or stationary.
Źródło:
Acta Physica Polonica A; 2012, 121, 1A; A-168-A-173
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Analysis of Wind Turbine Construction Safety System that Uses Vibroacoustic Diagnostics
Autorzy:
Szmechta, M.
Powiązania:
https://bibliotekanauki.pl/articles/1399405.pdf
Data publikacji:
2013-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
02.60.Lj
43.40.Le
Opis:
The paper presents an analysis of the results of monitored on-line Enercon E40/6.44 wind turbine with gearless designed synchronous generator and a nominal power of 600 kW. In recent months, this plant underwent with high frequency emergency stopped, the source of which was the acceleration control system located in the nacelle. This situation causes significant and unnecessary overload of the power plant components but most of all causes significant losses of production of renewable energy due to operational downtime. This article analyzes the circumstances of errors reported by the turbine control system associated with the acceleration sensor based on data recorded during several months of using on-line SCADA system. An assessment of the impact of a number of indicators related to the wind speed and direction of the nacelle on the operation of the safety system of the turbine has been carried out. Also the possible causes of irregularities were proposed, which may be the subject of further research, especially with the use of advanced diagnostics based on vibroacoustic method.
Źródło:
Acta Physica Polonica A; 2013, 124, 3; 574-577
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Frequency and Time-Frequency Analysis of Acoustic Cavitation Noise in Insulating Oils
Autorzy:
Szmechta, M.
Boczar, T.
Frącz, P.
Powiązania:
https://bibliotekanauki.pl/articles/1493273.pdf
Data publikacji:
2011-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
02.60.Lj
43.40.Le
Opis:
The paper presents some observations of ultrasound induced cavitation phenomenon in a mineral insulating oil. The acoustic cavitation phenomenon was generated at different signal frequencies and rms voltage value supplied to round piezoelectric transducers. Used transducers have created a high energy acoustic field in prepared insulating oil samples. The acoustic emission signal contains a broad-band noise and a fundamental frequency component and its harmonics, produced by the direct driving acoustic field. The paper presents the spectral analysis of acoustic emission signal observed during acoustic cavitation in insulating oils. To emphasize the changes in acoustic cavitation intensity also time-frequency analysis was used and some spectrograms were evaluated. The measurement uncertainty of some frequency-rms voltage pairs was very unfavorable. The main application expected with created cavitation measurement system is to develop a diagnostic tool for the aging of oil, based on the hypothesis that the measured cavitation intensity and spectrum could be affected by aging. Previous published measurements showed some relationship between insulating oil aging process and changes of acoustic emission of cavitations.
Źródło:
Acta Physica Polonica A; 2011, 120, 4; 744-747
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mathematical Model and Numerical Analysis of~AE Wave Generated by Partial Discharges
Autorzy:
Wotzka, D.
Boczar, T.
Fracz, P.
Powiązania:
https://bibliotekanauki.pl/articles/1493290.pdf
Data publikacji:
2011-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.40.Le
02.60.Lj
Opis:
Paper presents definition of a mathematical model describing acoustic emission signals generated by partial discharges occurring in oil immersed electric power transformers. Time runs, power spectral density graphs and spectrograms of acoustic emission signals generated in experiments, performed under laboratory conditions, and of equivalent signals, calculated on the basis of the mathematical model, are presented. Furthermore, results of numerical simulations of acoustic pressure distribution inside a tank filled with insulation oil are presented in the paper. In the center of the tank acoustic emission wave sources were placed, each generating signals described by the model developed.
Źródło:
Acta Physica Polonica A; 2011, 120, 4; 767-771
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Use of 3D Modeling in the Diagnosis of Power Capacitors with Acoustic Emission Method
Autorzy:
Boczar, T.
Błachowicz, A.
Borucki, S.
Zmarzły, D.
Powiązania:
https://bibliotekanauki.pl/articles/1417933.pdf
Data publikacji:
2012-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.40.Le
07.05.Tp
Opis:
The article presents the issue modelling the partial discharge phenomenon in engineering and scientific environments using hardware-based computer cluster. The authors present the results of research work on the phenomenon of acoustic emission from partial discharge occurring in power capacitors for power factor correction. The work includes the issues presentation and explanation of solutions enabling to create 3D spatial model of power capacitor. The authors proposed a simplified model of an acoustic test object aimed at improving the process of calculating the results.
Źródło:
Acta Physica Polonica A; 2012, 122, 5; 796-799
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Anusual Application of Partial Discharges to Diagnose of High Voltage Power Transformers
Autorzy:
Gacek, Z.
Szadkowski, M.
Malitowski, G.
Witos, F.
Olszewska, A.
Powiązania:
https://bibliotekanauki.pl/articles/1493101.pdf
Data publikacji:
2011-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.40.Le
52.80.s
07.50.Hp
Opis:
The article contains information on research carried out in Electric Faculty of Silesian University of Technology, made at test stations and aimed at diagnosis how is actual technical state of high voltage power oil transformers. Opinion on a state of transformers is based on analysis results of partial discharge measurements. Authors use simultaneously: electric, acoustic and dissolved gas analysis method. Applied acoustic method is the original own one. Non-conventional application of electric method is proposed, too. In the frame of chosen methodology the partial discharges are measured and next calculations of quantities describing partial discharges within particular methods are carried out in order to describe phenomena commonly for electric and acoustic method. Information sources about level and kind of partial discharges are measurement results obtained from electric method whereas information on places where partial discharges appear is contained in measurement results coming from acoustic method. Authors present selected application results of such a combined measuring method.
Źródło:
Acta Physica Polonica A; 2011, 120, 4; 609-615
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Acoustic Emission Study of Plastic Instabilities in AlSi1MgMn
Autorzy:
Molnárová, O.
Dobroň, P.
Chmelík, F.
Powiązania:
https://bibliotekanauki.pl/articles/1402161.pdf
Data publikacji:
2015-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.40.Le
81.40.Lm
62.20.F-
46.32.+x
Opis:
The influence of the strain rate and heat treatment on the occurrence of plastic instabilities in a cast AlSi1MgMn alloy was studied. The samples were uniaxially loaded in compression at various strain rates and at room temperature. The tests were done with concurrent acoustic emission monitoring and the acoustic emission parameters are correlated to the microstructure and to the stress-strain curves in order to better understand the patterns of plastic deformation. All samples exhibited the Portevin-Le Chatelier effect of different types, dependently on the heat treatment and the applied strain rate. The occurrence of the Portevin-Le Chatelier effect is manifested by acoustic emission signals with high amplitudes. Statistical analysis of the acoustic emission signals shows the power-law probability distribution.
Źródło:
Acta Physica Polonica A; 2015, 128, 4; 801-804
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Interrelation of Microstructure and Corrosion Resistance in Biodegradable Magnesium Alloys with Aluminum, Lithium and Rare Earth Additions
Autorzy:
Minárik, P.
Landa, M.
Lesná, I.
Zemková, M.
Jablonská, E.
Hadzima, B.
Janeček, M.
Král, R.
Powiązania:
https://bibliotekanauki.pl/articles/1402061.pdf
Data publikacji:
2015-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.05.-t
82.45.Bb
87.85.J-
43.40.Le
Opis:
The influence of equal channel angular pressing and rotary swaging on the microstructure and corrosion resistance was investigated in three magnesium alloys with the addition of aluminum, lithium and rare earth elements - AE21, AE42 and LAE442. The processing resulted in grain refinement in all cases; nevertheless, the effect on the corrosion resistance was ambiguous. A continuous increase of the polarization resistance during the gradual equal channel angular pressing was observed in the AE42 and LAE442 alloys, whereas there was almost no effect in the AE21 alloy. The rotary swaging of AE42 resulted in a decrease of polarization resistance. The increase of polarization resistance in the alloys with the higher concentration of alloying elements was caused by the combined effect of grain refinement and better dispersion of particles in the matrix thanks to shear deformation during equal channel angular pressing. In the AE42 alloy, the increase of the corrosion resistance after equal channel angular pressing was also proven by chemical analysis of the solution and acoustic emission detection. This beneficial effect was not observed when the concentration of alloying elements was lower or when the deformation mode was different from shearing.
Źródło:
Acta Physica Polonica A; 2015, 128, 4; 491-496
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Effect of Reversed Loading Conditions on the Mechanical Behaviour of Extruded Magnesium Alloy AZ31
Autorzy:
Bohlen, J.
Dobron, P.
Nascimento, L.
Parfenenko, K.
Chmelik, F.
Letzig, D.
Powiązania:
https://bibliotekanauki.pl/articles/1418429.pdf
Data publikacji:
2012-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.40.Le
61.72.Mm
81.05.Bx
81.70.Bt
Opis:
An indirectly extruded round bar of magnesium alloy AZ31 has been subjected to a cyclic test consisting of preloading in compression to different values of maximum stress followed by a single tensile test segment. Concurrent acoustic emission measurements were used to determine the active deformation mechanisms during plastic flow and work hardening. Electron backscattering diffraction was applied to obtain local orientation images in order to reveal twins and twinned fractions of the microstructure. Twins form preferentially in larger grains during the compression test segment and only with increasing stress do smaller grains show twinning. Some grains are completely re-oriented as a result of twinning. During the tensile test segment, untwinning is the most significant deformation mechanism although in some re-oriented grains new twins also nucleate. The acoustic emission count rates confirm that this is only the case after compression to higher stress levels.
Źródło:
Acta Physica Polonica A; 2012, 122, 3; 444-449
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Properties of Acoustic Emission Signals Coming from Partial Discharges Caused by Modeled Sources Immersed in Transformer Oil
Autorzy:
Witos, F.
Gacek, Z.
Powiązania:
https://bibliotekanauki.pl/articles/1807759.pdf
Data publikacji:
2009-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.40.Le
52.80.-s
77.22.Jp
84.70.+p
Opis:
Investigation results concerning acoustic emission signals coming from partial discharges generated by modeled sources are presented in the paper. These sources have been made using different bushing ends (without any extra elements and with a thread or a pike) situated directly in the oil, but without screens typical for partial discharge investigations in a bushing. Measurements have been carried out using own measuring acoustic emission system DEMA-COMP and - in a parallel way - computer-aided partial discharges measuring system TE 571 (produced by the firm Haefely Trench). Fundamental and advanced analysis of acoustic emission signals has been made. These signals were recorded in 20 measuring situations which need to multiple installation of acoustic emission sensors. Conclusions resultant from own originate advanced analysis of signals content description of properties revealed by defined acoustic emission descriptors.
Źródło:
Acta Physica Polonica A; 2009, 116, 3; 422-427
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of Properties Characteristic for Acoustic Emission Signals Recorded On-Line in Power Oil Transformers
Autorzy:
Witos, F.
Olszewska, A.
Szerszeń, G.
Powiązania:
https://bibliotekanauki.pl/articles/1493277.pdf
Data publikacji:
2011-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
52.80.-s
77.22.Jp
84.70.+p
43.40.Le
43.60.Lq
Opis:
Investigation results of properties characteristic for acoustic emission signals recorded in two selected power oil transformers are presented. Signals were put to the filtration, whereas components coming from partial discharges have been left. The calculations concerned: phase-time characteristics, averaging phase characteristics, averaging short time Fourier transform spectrograms, amplitude distributions of signals, values of acoustic emission descriptor with acronym ADC. On the ground of calculated basic characteristics and maps of ADC descriptor three areas have been selected on lateral walls of transformer tanks. Acoustic emission signals recorded in these areas were analyzed from the point of view how is influence of propagation path on these properties.
Źródło:
Acta Physica Polonica A; 2011, 120, 4; 759-762
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Acoustic Emission During Firing of the Illite-Based Ceramics with Fly Ash Addition
Autorzy:
Knapek, M.
Húlan, T.
Dobroň, P.
Chmelík, F.
Trník, A.
Štubňa, I.
Powiązania:
https://bibliotekanauki.pl/articles/1402156.pdf
Data publikacji:
2015-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.70.ph
61.43.Fs
65.60.+a
81.70.Pg
43.40.Le
Opis:
In this work, illite-based ceramic body with power plant fly ash addition (60 wt.% of illite, 30 wt.% of fly ash and 10 wt.% of illite fired at 1100°C) was investigated by the thermal analysis techniques (differential thermal analysis, thermodilatometry and thermogravimetry) and the acoustic emission technique. The green body was heated up to 1100°C at three different rates 2.5, 5, 10 K/min. The most intense acoustic emission was recorded at the highest rate 10 K/min. Mutual correlations between thermal analyses and acoustic emission data were also examined. The first acoustic emission response appears at 430°C, corresponding to a small endotherm on the DTA curve, where the thermal decomposition of mineral portlandite takes place. In the temperature range from 600 to 900°C, high acoustic emission activity correlates with dehydroxylation and expansion of the sample. At temperatures higher than 800°C, the source of acoustic emission signals is the thermal decomposition of calcite. The amorphous phase created from illite at 920°C becomes pyroplastic, therefore it is not documented by the acoustic emission technique.
Źródło:
Acta Physica Polonica A; 2015, 128, 4; 783-786
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Testing of Partial Discharges in Generator Coil Bars with the Help of Calibrated Acoustic Emission Method
Autorzy:
Witos, F.
Gacek, Z.
Opilski, Z.
Powiązania:
https://bibliotekanauki.pl/articles/1811569.pdf
Data publikacji:
2008-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.40.Le
43.60.Lg
52.80.s
77.22.Jp
84.70.+p
Opis:
Investigation results of acoustic emission signals coming from partial discharges within chosen generator coil bar, in relation to measurement results of apparent charge introduced by partial discharges sources, are presented in the article. Analysis is based on amplitude distributions calculated for acoustic emission signals, ordered at different measuring points for different values of the supply voltage. In order to assign acoustic emission signal to its advance degree a descriptor named by an acronym ADP (defined by authors) is calculated for each amplitude distribution. Descriptor families describing acoustic emission signals measured at particular measuring points (for different supply voltages) are presented in relation to apparent charge introduced by acoustic emission sources. These families concerning acoustic emission signals, measured at different measuring points for identical supply voltage, enable us to locate acoustic emission sources with maximum activity.
Źródło:
Acta Physica Polonica A; 2008, 114, 6A; A-249-A-258
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Location of Partial Discharge Sources and Analysis of Signals in Chosen Power Oil Transformers by Means of Acoustic Emission Method
Autorzy:
Olszewska, A.
Witos, F.
Powiązania:
https://bibliotekanauki.pl/articles/1418066.pdf
Data publikacji:
2012-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
52.80.-s
77.22.Jp
84.70.+p
43.40.Le
43.60.Lq
Opis:
The original system useful for analysis of signals recorded during investigations of partial discharges within power oil transformers by means of acoustic method is presented. This method includes the basic and advanced analysis of recorded data. In the frame of basic analysis of data recorded signals undergo filtration in chosen frequency bands and next the analysis is made - in domain of time, frequency, time-frequency and discrimination threshold. In the frame of advanced analysis of data the amplitude distributions of acoustic emission signals and the acoustic emission descriptors (defined by the authors) are calculated in order to outline maps of acoustic emission descriptors on lateral walls of a transformer; it is a base for location of sources of partial discharges by means of the original method consisted in determination of advance degree of a signal. Results of this analysis, for signals recorded in two chosen transformers with identical construction (partial discharge occurred only within one of them), are presented in the paper. The source of partial discharge, situated within oil near transformer tank, was localized; the revision confirmed this result. Properties of recorded emission acoustic signals at chosen measuring points situated on the tank, in function of distance between the partial discharge source and measuring points, are presented.
Źródło:
Acta Physica Polonica A; 2012, 122, 5; 921-926
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 21

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