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Wyszukujesz frazę "Ziółkowski, L." wg kryterium: Autor


Wyświetlanie 1-3 z 3
Tytuł:
Estimation of height changes of GNSS stations from the solutions of short vectors and PSI measurements
Autorzy:
Krynski, J.
Zak, L.
Ziolkowski, D.
Cisak, J.
Lagiewska, M.
Powiązania:
https://bibliotekanauki.pl/articles/145302.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
height changes
GNSS
Persistent Scatterer Interferometry
radar satelitarny
deformacja powierzchni
Opis:
Time series of weekly and daily solutions for coordinates of permanent GNSS stations may indicate local deformations in Earth’s crust or local seasonal changes in the atmosphere and hydrosphere. The errors of the determined changes are relatively large, frequently at the level of the signal. Satellite radar interferometry and especially Persistent Scatterer Interferometry (PSI) is a method of a very high accuracy. Its weakness is a relative nature of measurements as well as accumulation of errors which may occur in the case of PSI processing of large areas. It is thus beneficial to confront the results of PSI measurements with those from other techniques, such as GNSS and precise levelling. PSI and GNSS results were jointly processed recreating the history of surface deformation of the area of Warsaw metropolitan with the use of radar images from Envisat and Cosmo-SkyMed satellites. GNSS data from Borowa Gora and Jozefoslaw observatories as well as from WAT1 and CBKA permanent GNSS stations were used to validate the obtained results. Observations from 2000–2015 were processed with the Bernese v.5.0 software. Relative height changes between the GNSS stations were determined from GNSS data and relative height changes between the persistent scatterers located on the objects with GNSS stations were determined from the interferometric results. The consistency of results of the two methods was 3 to 4 times better than the theoretical accuracy of each. The joint use of both methods allows to extract a very small height change below the level of measurement error.
Źródło:
Geodesy and Cartography; 2017, 66, 1; 73-88
2080-6736
2300-2581
Pojawia się w:
Geodesy and Cartography
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ultra-Fast Current Aided Sintering of High Coercive Magnetic Powders and Composites
Autorzy:
Granek, K.
Ziółkowski, G.
Chrobak, A.
Klimontko, J.
Rak, J.
Zivotsky, O.
Gembalova, L.
Powiązania:
https://bibliotekanauki.pl/articles/351210.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
magnetic composites
ultra-fast current sintering
high coercive alloys
Opis:
The paper refers to pulverization and sintering of the (Fe80 Nb6 B14 )0.88 Tb0.12 high coercive alloy. The powder was sintered using the ultra-fast current aided method. It turned out that too long discharge time leads to appearing of a soft magnetic phase and simultaneously, decrease in coercivity of the compacted powder. Nevertheless, it was possible to establish preference technology parameters, preserving magnetic hardness of the alloy. As a final test, an impact of Co-powder addition on magnetic properties was studied. The introduced soft magnetic phase (about 20 wt. %) caused about 30% increase of magnetic remanence, which is a resultof direct exchange interactions between the two phases.
Źródło:
Archives of Metallurgy and Materials; 2019, 64, 2; 791-796
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the internal efficienty of a turbine stage: classical and computational fuid dynamics definitions
Autorzy:
Nastałek, L.
Karcz, M.
Sławiński, D.
Zakrzewski, W.
Ziółkowski, P.
Szyrejko, C.
Topolski, J.
Werner, B.
Badur, J.
Powiązania:
https://bibliotekanauki.pl/articles/175251.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
turbine stage
stage power
stage efficiency
losses
Opis:
Almost entire fleet of steam turbines in Poland was designed between 1950_1980 with the use of the so-called zero-dimensional (0D) calculation tools. For several years, design and modernization of the turbines occur in assistance with the state-of-the-art methods that describe working fluid flow field based on three-dimensional (3D) models and computational fluid dynamics (CFD) codes. This cooperation between 0D and 3D codes requires exchange of overall, integral information such as: power, efficiency, heat and mass fluxes. In consequence the question arises regarding the cohesion of definitions, and particularly regarding the correctness of the definition for internal efficiency of the turbine's stage and the turbine as a whole. In the present paper we formulate basic definitions reason of efficiency that are naturally adapted to the numerical 0D and 3D models. We show that the main reason of differences between the definitions in 0D and 3D is the definition of the theoretical work of the stage lt. In the classical 0D models, mostly employed is the isentropic approach, and hence the isentropic efficiency occurs. Meanwhile, in the increasingly common 3D approach (most likely by CFD), we use more physically correct pathway by subtracting energy loss from the available energy, that leads to the polytropic definition of efficiency. We show an example of computing the efficiency and the 3D losses, denoted with additional subscript CFD, we also discuss benefits of this definition in comparison with the isentropic classical definition in 0D.
Źródło:
Transactions of the Institute of Fluid-Flow Machinery; 2012, 124; 17-39
0079-3205
Pojawia się w:
Transactions of the Institute of Fluid-Flow Machinery
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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