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Wyszukujesz frazę "wind condition" wg kryterium: Temat


Tytuł:
Air movement characteristics inside a cow barn with natural ventilation under no-wind conditions in the winter season
Autorzy:
Herbut, P.
Tematy:
air movement
cow barn
natural ventilation
no-wind condition
winter season
air circulation
barn
building
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Wydawca:
Polska Akademia Nauk. Stowarzyszenie Infrastruktura i Ekologia Terenów Wiejskich PAN
Powiązania:
https://bibliotekanauki.pl/articles/61769.pdf  Link otwiera się w nowym oknie
Opis:
The paper presents results of air movement observations inside a cow barn (Fermbet construction type) adapted for a loose housing system. The conducted experiments made it possible to determine directions and characteristics of ventilated air flux in selected areas of the building as well as mark out areas where air stood still. In addition, the study offers recommendations regarding effective ventilation systems in the occupied zone under no-wind conditions.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Currents and waves in the Northern Gulf of Riga: measurement and long-term hindcast
Autorzy:
Suursaar, U.
Kullas, T.
Aps, R.
Tematy:
hydrodynamic modelling
water exchange
wave
Riga Gulf
Baltic Sea
long-term hindcast
wave measurement
wind force
wind condition
atmospheric circulation
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Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Powiązania:
https://bibliotekanauki.pl/articles/47862.pdf  Link otwiera się w nowym oknie
Opis:
Based on measurements of waves and currents obtained for a period of 302 days with a bottom-mounted RDCP (Recording Doppler Current Profiler) at two differently exposed locations, a model for significant wave height was calibrated separately for those locations; in addition, the Gulf of Riga-Vainameri 2D model was validated, and the hydrodynamic conditions were studied. Using wind forcing data from the Kihnu meteorological station, a set of current, water exchange and wave hindcasts were obtained for the period 1966–2011. Current patterns in the Gulf and in the straits were wind-dependent with characteristic wind switch directions. The Matsi coast was prone to upwelling in persistent northerly wind conditions. During the hindcast period, currents increased along the Koiguste coast and in the Suur Strait, waves decreased noticeably off Koiguste but fluctuated without a clear linear trend near Matsi. The spatially contrasting results for differently exposed coasts were related to the corresponding variations in local wind conditions and to changes in atmospheric circulation patterns over northern Europe.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Flow, waves and water exchange in the Suur Strait, Gulf of Riga, in 2008
Autorzy:
Raudsepp, U.
Laanemets, J.
Haran, G.
Alari, V.
Pavelson, J.
Kouts, T.
Tematy:
flow
wave
water exchange
Suur Strait
Riga Gulf
modelling
shear velocity
Baltic Sea
wind
wind condition
storm
wave heigh
sediment
seasonal cycle
horizontal distribution
outflow
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Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Powiązania:
https://bibliotekanauki.pl/articles/49038.pdf  Link otwiera się w nowym oknie
Opis:
Wind, flow and wave measurements were performed in November–December in 2008 in the relatively narrow and shallow Suur Strait connecting the waters of the V¨ainameri and the Gulf of Riga. During the measurement period wind conditions were extremely variable, including a severe storm on 23 November. The flow speed along the strait varied between ±0.2 m s−1, except for the 0.4 m s−1 that occurred after the storm as a result of the sea level gradient. The mean and maximum significant wave heights were 0.53 m and 1.6 m respectively. Because of their longer fetch, southerly winds generated higher waves in the strait than winds from the north. All wave events caused by the stronger southerly winds induced sediment resuspension, whereas the current-induced shear velocity slightly exceeded the critical value for resuspension only when the current speed was 0.4 m s−1. A triplenested two-dimensional high resolution (100 m in the Suur Strait) circulation model and the SWAN wave model were used to simulate water exchange in 2008 and the wave-induced shear velocity field in the Suur Strait respectively. Circulation model simulations demonstrated that water exchange was highly variable, that cumulative transport followed an evident seasonal cycle, and that there was an gross annual outflow of 23 km3 from the Gulf of Riga. The horizontal distribution of waveinduced shear velocity during the strong southerly wind event indicated large shear velocities and substantial horizontal variability. The shear velocities were less than the critical value for resuspension in the deep area of the Suur Strait.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparison of advanced signal-processing methods for roller bearing faults detection
Autorzy:
Urbanek, J.
Barszcz, T.
Uhl, T.
Tematy:
fault detection
condition monitoring
rolling element bearing
wind turbine
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Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:
https://bibliotekanauki.pl/articles/221168.pdf  Link otwiera się w nowym oknie
Opis:
Wind turbines are nowadays one of the most promising energy sources. Every year, the amount of energy produced from the wind grows steadily. Investors demand turbine manufacturers to produce bigger, more efficient and robust units. These requirements resulted in fast development of condition-monitoring methods. However, significant sizes and varying operational conditions can make diagnostics of the wind turbines very challenging. The paper shows the case study of a wind turbine that had suffered a serious rolling element bearing (REB) fault. The authors compare several methods for early detection of symptoms of the failure. The paper compares standard methods based on spectral analysis and a number of novel methods based on narrowband envelope analysis, kurtosis and cyclostationarity approach. The very important problem of proper configuration of the methods is addressed as well. It is well known that every method requires setting of several parameters. In the industrial practice, configuration should be as standard and simple as possible. The paper discusses configuration parameters of investigated methods and their sensitivity to configuration uncertainties.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparison of requirements for vibration-based condition monitoring of a vertical-axis vs. horizontal-axis wind turbine
Porównanie wymagań systemu monitorowania i diagnostyki dla turbin wiatrowych o poziomej i pionowej osi
Autorzy:
Kotulski, L.
Jabłoński, A.
Tematy:
wind turbine
condition monitoring
vibrations
turbina wiatrowa
ocena stanu technicznego
drgania
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Wydawca:
Polska Akademia Nauk. Polskie Towarzystwo Diagnostyki Technicznej PAN
Powiązania:
https://bibliotekanauki.pl/articles/329326.pdf  Link otwiera się w nowym oknie
Opis:
The paper compares the requirements for vibration-based condition monitoring system for two seemingly similar rotary machines, namely horizontal and vertical-axis wind turbines. The paper shows that the differences in the design have a significant influence on both, operational parameters and wind energy conversion, and what are the consequences from condition monitoring point-of-view. In addition, the authors present a list of obstacles during worldwide development of vibration-based guidelines, which has led to major constraints within practical data acquisition and processing. Finally, the paper presents comparison of experimental data and complete schemes of mechanical components of drive trains of both types of turbines.
W artykule porównano wymagania dla systemu monitorowania dwóch pozornie podobnych maszyn wirnikowych, mianowicie turbin wiatrowych o poziomej i pionowej osi obrotu wału głównego. Autorzy pokazali analizę, z której wynika, że różnice w konstrukcji mają znaczący wpływ zarówno na parametry eksploatacyjne, jak i na konwersję energii wiatrowej oraz jakie są konsekwencje tych różnic z punktu widzenia oceny stanu technicznego. Ponadto, autorzy przedstawili listę powodów, które sprawiły, że do dnia dzisiejszego, światowym organizacjom udało się opracować się jedynie normy odnoszące się do analizy niektórych typów maszyn w wąskim przedziale warunków operacyjnych. Na koniec przedstawiono porównanie danych eksperymentalnych i schematów mechanicznych elementów układów napędowych obu typów turbin.
Dostawca treści:
Biblioteka Nauki
Artykuł

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