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Wyszukujesz frazę "Zakrzewski, W." wg kryterium: Autor


Tytuł:
Acoustic emission signals associated with prebreakdown state in air high voltage insulating systems
Autorzy:
Dobrzycki, A.
Opydo, W.
Zakrzewski, S.
Powiązania:
https://bibliotekanauki.pl/articles/97311.pdf
Data publikacji:
2015
Wydawca:
Politechnika Poznańska. Wydawnictwo Politechniki Poznańskiej
Tematy:
high voltage insulating system
breakdown voltage
acoustic emission method
dielectric coatings
Opis:
The paper presents the method of acoustic emission (AE) in the study of the state of insulation systems with air as the high-voltage insulation. The tested object was a planar system of electrodes made of aluminum. In addition, the analysis of AE signals and the impact on these signals the presence of dielectric coating on the electrode surfaces of aluminum was tested. We examined the influence of saturation (seal) these coatings on the dielectric strength of the insulation system. The study was conducted at an air pressure values 1·105, 3·105 and 5·105 Pa. The strength of the electrical systems were tested at alternating voltage with a frequency of 50 Hz. Noted pros and cons of using the method of EA in the context of the assessment of high-voltage electric insulation devices. The presented results confirm the possibility of using acoustic emission method, not only for identifying vulnerable areas, but also to predict the time of of further use of high voltage device.
Źródło:
Computer Applications in Electrical Engineering; 2015, 13; 278-286
1508-4248
Pojawia się w:
Computer Applications in Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of novel serum markers of fibrosis and angiogenesis in patients with alcoholic liver cirrhosis
Autorzy:
Prystupa, A.
Kiciński, P.
Luchowska-Kocot, D.
Nowicki, G.
Dzida, G.
Myśliński, W.
Zakrzewski, M.
Mosiewicz, J.
Panasiuk, L.
Powiązania:
https://bibliotekanauki.pl/articles/28762972.pdf
Data publikacji:
2020
Wydawca:
Instytut Medycyny Wsi
Źródło:
Annals of Agricultural and Environmental Medicine; 2020, 27, 4; 568-573
1232-1966
Pojawia się w:
Annals of Agricultural and Environmental Medicine
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Co$\text{}^{2+}$ Ions in ZnS$\text{}_{x}$Se$\text{}_{1-x}$:Co - ESR and Optical Studies
Autorzy:
Świątek, K.
Surkova, T. P.
Sienkiewicz, A.
Zakrzewski, A. J.
Godlewski, M.
Giriat, W.
Powiązania:
https://bibliotekanauki.pl/articles/1992580.pdf
Data publikacji:
1998-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.Gs
76.30.Fc
78.55.Et
Opis:
The electron spin resonance of Co$\text{}^{2+}$ ions in ZnS$\text{}_{x}$Se$\text{}_{1-x}$:Co mixed crystals was measured at temperature of 3 K and microwave frequency of 9.47 GHz. Trigonal Co$\text{}_{Zn}^{2+}$-S center in the ZnS$\text{}_{0.001}$Se$\text{}_{0.999}$:Co crystal was identified and parameters of relevant spin Hamiltonian were determined. Influence of alloy disorder in the anion sublattice on the Co$\text{}_{Zn}^{2+}$ ground and first excited states is briefly discussed.
Źródło:
Acta Physica Polonica A; 1998, 94, 3; 593-596
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Cold Atomic Gases in Optical Lattices with Disorder
Autorzy:
Schulte, T.
Drenkelforth, S.
Kruse, J.
Ertmer, W.
Arlt, J. J.
Kantian, A.
Sanchez-Palencia, L.
Santos, L.
Sanpera, A.
Sacha, K.
Zoller, P.
Lewenstein, M.
Zakrzewski, J.
Powiązania:
https://bibliotekanauki.pl/articles/2044614.pdf
Data publikacji:
2006-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
03.75.Kk
03.75.Lm
05.30.Jp
64.60.Cn
Opis:
Cold atomic gases placed in optical lattices enable studies of simple condensed matter theory models with parameters that may be tuned relatively easily. When the optical potential is randomized (e.g. using laser speckle to create a random intensity distribution) one may be able to observe Anderson localization of matter waves for non-interacting bosons, the so-called Bose glass in the presence of interactions, as well as the Fermi glass or quantum spin glass for mixtures of fermions and bosons.
Źródło:
Acta Physica Polonica A; 2006, 109, 1; 89-99
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dynamic analysis of the control stage of a high speed steam turbine
Autorzy:
Sławiński, D.
Zakrzewski, W.
Powiązania:
https://bibliotekanauki.pl/articles/175498.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
control stage
residual stresses
initial displacement blade
vibrations blade
Opis:
This paper analyzes the possibility of resonances within a control stage of a high speed turbine. An original method for steady state operation is used for the analysis of the stiffness matrix representing: initial displacement blade (nominal shape blade obtained by nominal working point of turbine) and residual stresses following local crossing yield plastic strain. In the analysis there has been found a possibility of occurance of the resonance frequency, and mistuning by showing the safe working ranges. The calculation used the 3D modal and harmonic analysis within computational solid dynamics (CSD) and the results were compared with the 0D data from literature. After local crossing of yields stresses, on the basis of the harmonic analysis, there has been shown operation of the blade in the resonance point. Before crossing the yield stresses the blade is working in mistuning and a safe point.
Źródło:
Transactions of the Institute of Fluid-Flow Machinery; 2012, 124; 41-49
0079-3205
Pojawia się w:
Transactions of the Institute of Fluid-Flow Machinery
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electric strength of air and sulphur hexafluoride in the system with electrodes covered with dielectric double layer
Autorzy:
Zakrzewski, S.
Opydo, W.
Powiązania:
https://bibliotekanauki.pl/articles/97710.pdf
Data publikacji:
2012
Wydawca:
Politechnika Poznańska. Wydawnictwo Politechniki Poznańskiej
Tematy:
electric strength air
sulphur hexafluoride
aluminum oxide
Opis:
The paper presents the results of the study on the effect of dielectric double layer at electrode surface on electric strength of compressed air and compressed sulphur hexafluoride. The research has been carried out at alternate voltage of 50 Hz frequency. It was found that thin insulation coating laid on electrode surface, composed of aluminum oxide layer with a layer of electro-insulation polyester lacquer significantly improves electric strength of air and sulphur hexafluoride. It was found that maximum growth of electric strength of these gases was caused by the coating under their pressures exceeding the atmospheric one (3·105 and 5·105 Pa). The changes in configuration of electrode surface of the insulation systems caused by sparking over have been examined with scanning laser confocal microscope.
Źródło:
Computer Applications in Electrical Engineering; 2012, 10; 394-401
1508-4248
Pojawia się w:
Computer Applications in Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Energy Level Position of Ni and Band Offsets in Zn$\text{}_{1-x}$Cd$\text{}_{x}$Sc:Ni and ZnS$\text{}_{x}$Sc$\text{}_{1-x}$:Ni
Autorzy:
Surkova, T.
Giriat, W.
Godlewski, M.
Kaczor, P.
Zakrzewski, A. J.
Permogorov, S.
Tenishev, L.
Powiązania:
https://bibliotekanauki.pl/articles/1934015.pdf
Data publikacji:
1995-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.20.Wc
71.55.Gs
Opis:
Absorption and reflectivity measurements have been carried out for Zn$\text{}_{1-x}$Cd$\text{}_{x}$Se:Ni and ZnS$\text{}_{x}$Se$\text{}_{1-x}$:Ni solid solutions. Energy level positions of nickel 2+/1+ charge state have been used for estimation of band offsets for the valence and conduction bands of ZnCdSe/ZnSe and ZnSSe/ZnSe. Intra-shell transitions of Ni$\text{}^{2+}$ were also studied.
Źródło:
Acta Physica Polonica A; 1995, 88, 5; 925-928
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Estimation of the steam condensation flow via CFD methods
Autorzy:
Zakrzewski, W.
Karcz, M.
Kornet, S.
Powiązania:
https://bibliotekanauki.pl/articles/175353.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
condensation model
steam turbine
CFD
Opis:
The results of numerical simulations to predict the performance of different steam models have been presented. All of the considered models of steam condensation have been validated on the base of benchmark experiment employing expansion in nozzle and next on the low pressure part of the steam turbine stage. For numerical analysis three models have been finally used - the ideal steam model without condensation, equilibrium steam model and a nonequilibrium steam model. It was confirmed that only the inclusion of the nonequilibrium effects in the computations can lead to a proper prediction of the condensation phenomena in the test nozzle. However, the basic characteristics of the low-pressure turbine can be succesfully estimated using a simple ideal steam or the equilibrium condensation model.
Źródło:
Transactions of the Institute of Fluid-Flow Machinery; 2012, 124; 111-124
0079-3205
Pojawia się w:
Transactions of the Institute of Fluid-Flow Machinery
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Indium Doping of CdTe Grown by Molecular Beam Epitaxy
Autorzy:
Karczewski, G.
Zakrzewski, A.
Kutrowski, M.
Jaroszyński, J.
Dobrowolski, W.
Grodzicka, E.
Janik, E.
Wojtowicz, T.
Kossut, J.
Barcz, A.
Powiązania:
https://bibliotekanauki.pl/articles/1932089.pdf
Data publikacji:
1995-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.55.Ln
73.61.Ga
Opis:
We report on n-type indium doping of CdTe films grown by molecular beam epitaxy on (001) GaAs substrates. By adjusting the flux of In atoms we can precisely control the carrier concentration over three orders of magnitude - from 8 × 10$\text{}^{14}$ up to 1.3 × 10$\text{}^{18}$ cm$\text{}^{-3}$. In agreement with earlier reports we confirmed that Cd overpressure plays an important role in the doping process. The doping appears to be most effective for Cd/Te pressure ratio of 1.5. For this value of Cd/Te pressure ratio essentially 100% efficiency of doping is achieved at low In concentrations (< 10$\text{}^{18}$ cm$\text{}^{-3}$). At higher In concentrations acceptor impurities compensate shallow donors limiting the concentration of free carriers.
Źródło:
Acta Physica Polonica A; 1995, 87, 1; 241-244
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Luminescence Quantum Efficiency of Mn$\text{}^{2+}$ States in ZnSe:Mn as Studied by means of Photoacoustic Spectroscopy
Autorzy:
Męczyńska, H.
Łęgowski, S.
Dąbrowska, W.
Popielarski, M.
Ogielski, Z.
Zakrzewski, J.
Powiązania:
https://bibliotekanauki.pl/articles/1929770.pdf
Data publikacji:
1993-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.85.+f
62.65.+k
78.20.Hp
Opis:
The photoacoustic spectroscopy with a piezoelectric transducer was employed to determined the quantum efficiency for low Mn concentration in ZnSe monocrystals. The photoacoustic spectra were measured using the continuous wave excitation and nanosecond pulse method.
Źródło:
Acta Physica Polonica A; 1993, 84, 4; 823-825
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mineral content of muscle tissue of rainbow trout (Oncorhynchus mykiss Walbaum)
Autorzy:
Siemianowska, E.
Barszcz, A.A.
Skibniewska, K.A.
Markowska, A.
Polak-Juszczak, L.
Zakrzewski, J.
Wozniak, M.
Szarek, J.
Dzwolak, W.
Powiązania:
https://bibliotekanauki.pl/articles/13811.pdf
Data publikacji:
2016
Wydawca:
Uniwersytet Warmińsko-Mazurski w Olsztynie / Polskie Towarzystwo Magnezologiczne im. Prof. Juliana Aleksandrowicza
Opis:
Fish are most often considered as a rich source of valuable fat, although sometimes the high quality of fish meat protein is also emphasized, but there is comparably little information on the mineral composition of fish meat. Chemical composition, caloric value and health safety of fish as food depend on many factors, of which the rearing conditions are most influential. Aside from environmental conditions, production technology is a major determinant of the quality and nutritional value of trout. In this study, the influence of a farming technology on the content of minerals in the muscle tissue of rainbow trout (Oncorhynchus mykiss Walbaum) netted in various Polish regions has been assessed. Fish were caught in autumn 2010 and 2011 and spring 2011, at 3 farms with a water flow-through system and 3 farms with water recirculation. The trout muscle tissue contained: 188.4 - 518.4 mg kg-1 of calcium, 306.9 - 338.1 mg kg-1 of magnesium, 464.0 - 718.2 mg kg-1 of sodium, 4.5 - 6.9 mg kg-1 of zinc, 2485.7 - 2823.6 mg kg-1 of phosphorous, 4261.2 - 4615.4 mg kg-1 of potassium, 3.0 - 9.4 mg kg-1 of iron and 0.09 – 11.74 mg kg-1 of copper. The farming technology influenced the content of calcium, sodium, zinc, iron and copper but had no effect on the content of magnesium, phosphorous and potassium in rainbow trout muscle tissue. Trout farmed in water recirculation systems contained higher amounts of most elements than the fish reared in water flow-through systems. The season of sample collection (date of netting) also affected the content of sodium, zinc, phosphorus, iron and copper. The fish farming site (localization of the farm) determined the content of most of the minerals except magnesium. Rainbow trout is a good source of phosphorous and potassium in a human diet, significantly covering the daily demand for the elements.
Źródło:
Journal of Elementology; 2016, 21, 3
1644-2296
Pojawia się w:
Journal of Elementology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modeling of Baumann’s turbine stage operation. Part I - Flow
Modelowanie pracy turbinowego stopnia Baumanna, część I - przepływ
Autorzy:
Zakrzewski, W.
Nastałek, L.
Badur, J.
Jesionek, K.
Straś, K.
Masłyk, M.
Powiązania:
https://bibliotekanauki.pl/articles/172821.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
turbina kondensacyjna
stopień Baumanna
symulacja komputerowa
condensing turbine
Baumann's stage
computer simulation
Opis:
A Baumann stage is one of the way, to increase the turbine’s output without an increase of the last stage blade length. Due to the complicated design, the Baumann’s blade technology is complex, and its efficiency is lower in comparison to a free-standing blade. Currently that stage is used mostly in back pressure cogeneration heating turbines. This paper presents the operation of low pressure part steam turbine in different conditions, calculated with two models of steam and compared to measurements and TURBINA 0D code.
W pracy nawiązano do stopnia Baumanna i całej części niskoprężnej turbiny kondensacyjnej typu 13K215, w której występują różnice między pomiarami a danymi projektowymi określonymi na podstawie klasycznych narzędzi obliczeniowych typu „0D TURBINA”. Dlatego celem artykułu jest próba wyjaśnienia tych różnic poprzez, dokładniejszą niż 0D, symulację 3D przepływu kondensującej pary w części niskoprężnej turbiny.
Źródło:
Archiwum Energetyki; 2012, 42, 2; 175-183
0066-684X
Pojawia się w:
Archiwum Energetyki
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modelling of the Baumann turbine stage operation Part II. Free and kinetic vibrations
Modelowanie pracy turbinowego stopnia Baumanna, część II – drgania swobodne i wymuszone kinetycznie
Autorzy:
Jesionek, K.
Kron, J.
Zakrzewski, W.
Sławiński, D.
Kornet, S.
Ziółkowski, P.
Badur, J.
Powiązania:
https://bibliotekanauki.pl/articles/172994.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
turbina kondensacyjna
stopień Baumanna
CSD
drgania swobodne
drgania wymuszone
condensing turbine
Baumann's stage
random vibrations
forced vibration
Opis:
In this paper has been presented a methodology of validation a novel mathematical model dedicated to evaluation and prediction of material degradation and damage of steam turbine elements such as blades, valves, and pipes due to three mechanisms: stress-corrosion, high-temperature creep and low-cyclic fatigue. The validation concept is based on an experimental setup manufactured in the Laboratory of Faculty of Mechanical and Power Engineering, Wrocław UT. The concept of validation by comparison of measured and numerically predicted eigen-frequencies and eigen-modes of different turbine elements within laboratory conditions are presented, and mathematical models of three damage mechanisms have been described. Using the mentioned method of experimental validation based on comparisons of eigen-frequencies, we could calibrate yet unknown coefficients in the turbine damage model. A practical aim is an implementation of a novel life-time module for the BOTT (block of thermal stresses restriction) system. In particular the stress-corrosion factor will be added for the advanced numerical control system, creating in such way a universal, flexible and a complete tool for monitoring degrees of degradation, corrosion and damage of critical points in a steam turbine.
Niniejszy artykuł jest kolejnym z cyklu, którego celem jest opracowanie numerycznego narzędzia badawczego opartego na CSD (Computational Solid Dynamics). Zadaniem jego byłaby weryfikacja stanu wytrzymałościowego i dynamicznego trudnodostępnych dla pomiarów urządzeń w turbinie takich jak: rurociągi pary świeżej, zawory, wirniki czy łopatki. Narzędzie obserwowałoby rozwijające się mechanizmy: korozji, pełzania wysokotemperaturowego i niskocyklicznego zmęczenia. Ostateczną walidacje modeli numerycznych z eksperymentem zaplanowano wykonać w Laboratorium Wydziału Mechaniczno-Energetycznego Politechniki Wrocławskiej. W tej części cyklu artykułów pokazano m.in. walidację modelu numerycznego z pomiarami drgań, jakie wykonano na stanowisku badawczym oraz w skrócie opisano poszczególne moduły narzędzia. Po implementacji wszystkich modeli do systemu nadzorującego pracę turbozespołu o nazwie BOTT (Blok Ograniczeń Termicznych), powstanie zupełnie nowy, elastyczny i kompletny system monitorujący stopień degradowania się elementów turbozespołu o nazwie ANCS (Advance Numerical Control Systems) działający w sposób on-line.
Źródło:
Archiwum Energetyki; 2013, 43, 1/2; 61--74
0066-684X
Pojawia się w:
Archiwum Energetyki
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nadużywanie alkoholu w biografiach młodocianych toksykomanów
Excessive Drinking in the Biographies of Young Adult Drug Addicts
Autorzy:
Tomczak, Jerzy W.
Zakrzewski, Paweł
Powiązania:
https://bibliotekanauki.pl/articles/699052.pdf
Data publikacji:
1982
Wydawca:
Polska Akademia Nauk. Instytut Nauk Prawnych PAN
Tematy:
środki uzależniające
uzależnienie od substancji
młodociani
nadużywanie alkoholu
toksykomania
alcohol abuse
addictive substances
substance dependence
juvenile
toxicomania
Opis:
In the present study the young adult drug addicts are discussed who were included in the multidisciplinary research conducted by the Department of Mental Health of the Polish Academy of Sciences. An attempt is made to reveal the psycho-social mechanisms which cause the co-existence of excessive drinking and taking other drugs causing dependence. This problem is insufficiently elucidated both in Polish and foreign scientific literature. We do not cite here the description of the methods employed in the study of sufficient information is provided for in the summary of the study of the progress of dependence and changes in the social behavior of young adult drug addicts, published in the present volume. Attention should be drawn to a difference in the methods: in the present study, we deal first of all with young adult males. Among girls, excessive drinking does not play any important role, therefore the coexistence of alcohol and other drugs in their life stories occurs comparatively rarely. The phenomenon of excessive drinking occurred in 48 boys - drug addicts, which makes 58% of the total of 83 boys. Excessive drinking generally preceded the taking of drugs; alcohol was also used as a mean to soften the abstinence symptoms due to a temporary lack of the basic drug; drinking resulted also from a futile attempt at withdrawal from an advanced morphine habit. The cases of simultaneous drinking and taking of narcotic drugs in order to achieve more intense experiences were rare, as well as those of alternate drinking and taking drugs; in this last case, it meant that the individual was first of all anxious to strenghten the bonds between the members of the group, not yet feeling any mental nor all the more physical symptoms of dependence on alcohol or other drugs. To sum up, we noted in the large part of the addicts the easiness of changing from narcotic drugs to alcohol and vice versa. The possible general interpretation of these facts is as follows: individuals with certain personality deficiencies are characterized by a low tolerance to defeats, stress and tensions, which causes the need to seek the so-called “mental prothesis” or the desire to change one’s own state of mind. These needs and desires can be aggravated by the intensified symptoms of puberty, among them excessive and inadequate emotional reactions, discontent with one’s everyday duties and necessities, states of depression and dysphoria. Both alcohol and narcotic drugs can soothe these needs on temporarily satisfy them, though naturally not identically nor to the same extent. Therefore, where greater efficiency of reaction is desired, the individual may pass on to narcotic drugs. On the other hand, when the person is first of all anxious to soothe the conflicts with his immediate environment, to avoid pressure by the police and the sentence, i.e., meet with more indulgence on the part of his environment and at the same time to have less problems with purchasing a particular drug, and thus to avoid in future the painful  withdrawal symptoms - in such cases the conversion from morphine or other drugs to alcohol is probable. Among the individuals who had often drunk alcohol before they started taking narcotic drugs, the later reverse to alcohol to soothe withdrawal  symptoms caused by the lack of morphine or other drugs which brought about the state of dependence, is highly probable as the individuals in question already know the influence, of alcohol and the favourable reaction of their organism to it.
Źródło:
Archiwum Kryminologii; 1982, VIII-IX; 389-401
0066-6890
2719-4280
Pojawia się w:
Archiwum Kryminologii
Dostawca treści:
Biblioteka Nauki
Artykuł

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