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Wyszukujesz frazę "Badran, R." wg kryterium: Autor


Wyświetlanie 1-4 z 4
Tytuł:
The Effect of Power Density on Diffusion Length and Energy Gap of a-Si:H and nc-Si:H Thin Films Prepared by PECVD Technique
Autorzy:
Badran, R.
Al-Amodi, H.
Yaghmour, S.
Shaklan, S.
Bruggemann, R.
Han, X.
Xiong, S.
Powiązania:
https://bibliotekanauki.pl/articles/1419002.pdf
Data publikacji:
2012-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.20.-e
78.20.Ci
73.61.Jc
78.30.Ly
Opis:
The increase in power density of 0.3, 0.5, 0.6, and 0.7 W $cm^{-2}$ for hydrogenated amorphous and nanocrystalline silicon (a-Si:H and nc-Si:H) thin film samples prepared by plasma enhanced chemical vapor deposition technique causes an increase in crystalline volume fraction when the silane concentration is fixed. This increase in crystalline volume fraction is correlated to the absorption coefficient and refractive index which are determined from ellipsometric measurements. The crystallinity of samples is studied by both Raman and X-ray diffraction techniques. A mild change in the optical energy gap around an average value of 1.8 eV is noticed due to the observed change in the degree of crystallinity of the samples when power density increases. Moreover, the ambipolar diffusion length measured by the steady-state photocarrier grating technique is found to change with the increase in power density. The values of some obtained optical parameters are compared to a standard crystalline sample.
Źródło:
Acta Physica Polonica A; 2012, 122, 3; 576-580
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Relationships between water temperature, nutrients and dissolved oxygen in the Northern Gulf of Aqaba, Red Sea
Autorzy:
Manasrah, R.
Raheed, M.
Badran, M.I.
Powiązania:
https://bibliotekanauki.pl/articles/49092.pdf
Data publikacji:
2006
Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Tematy:
stratification
nutrient
Aqaba Gulf
temperature
sea water
Red Sea
oxygen
Opis:
Five years (1998, 2000–2003) of summer records of temperature, nutrients and dissolved oxygen concentrations in the upper 400 m of the water column of the northern Gulf of Aqaba were employed to produce a simple statistical model of the relationship between temperature versus nitrate, phosphate, silicate andd issolved oxygen concentrations. Temperature profiles in the upper 400 m during summer revealeda clear thermocline in the upper 200 m. This was reflected in nutrient ando xygen concentrations as nitrate, phosphate, and silicate increasedfr om the surface to deep water while dissolved oxygen decreased. The best fit relationship between temperature versus nitrate andphosphate was inverse linear and the best fit correlation between temperature versus silicate andd issolvedo xygen was fractional. The observedn utrient concentrations were shaped by a combination of the hydrodynamics and biological factors. Deep winter mixing and high nutrient concentrations dominate during winter. Shortly after the water stratifies in spring, the nutrients are drawn down by phytoplankton during the spring bloom and remain low throughout the rest of the year. The regression equations presented here will be useful in estimating nutrient concentrations from temperature records as long as the annual natural cycle is the main driver of nutrient concentrations and external inputs are insignificant. Deviations from these relationships in the future could provide insight into modifications in the nutrient concentrations probably resulting from new nutrient sources, such as anthropogenic inputs.
Źródło:
Oceanologia; 2006, 48, 2
0078-3234
Pojawia się w:
Oceanologia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Circulation and winter deep-water formation in the Northern Red Sea
Autorzy:
Manasrah, R.
Badran, M.
Lass, H.U.
Fennel, W.
Powiązania:
https://bibliotekanauki.pl/articles/49153.pdf
Data publikacji:
2004
Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Tematy:
Aqaba Gulf
eddy
deep-water formation
winter
circulation
Red Sea
Opis:
Water mass characteristics and circulation patterns in the Gulf of Aqaba and northern Red Sea were studied for the first time during the r/v ‘Meteor’ cruise leg 44/2 from February 21st to March 7th 1999 using temperature-salinity profiles and current observations. The deep water in the northern Red Sea had similar characteristics to the well-mixed upper 450 m of water in the Gulf of Aqaba. This indicates that the winter mixed waters of the Gulf of Aqaba contribute significantly to deep-water in the northern Red Sea. Mixing in the Gulf of Aqaba is an annually repeated event that starts with the cooling of the surface water during November–December and reaches a maximum, which in most years extends down the entire water column in March–April. Waters deeper than the mixed layer in the Gulf seems to be rather passive and play no specific role in water mass formation in the northern Red Sea. In contrast to the Gulf of Aqaba, the upper 200 m of the northern Red Sea were stratified (21.5–23.5◦C, and 40.0–40.3 PSU). Stratification at the Strait of Tiran was weak (21.6–22.0◦C, and 40.3–40.5 PSU) and disappeared abruptly in the Gulf of Aqaba (21.4–21.6◦C, and 40.6–40.7 PSU). A well-developed cyclonic gyre with a diameter of about 50–60 km and maximum velocity of about 0.4 m s−1 was observed in the stratified upper 200 m of the northern Red Sea waters. The gyre may contribute to the preconditioning for intermediate water formation in the northern Red Sea.
Źródło:
Oceanologia; 2004, 46, 1
0078-3234
Pojawia się w:
Oceanologia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nutrient flux fuels the summer primary productivity in the oligotrophic waters of the Gulf of Aqaba, Red Sea
Autorzy:
Badran, M.I.
Rasheed, M.
Manasrah, R.
Al-Najjar, T.
Powiązania:
https://bibliotekanauki.pl/articles/47744.pdf
Data publikacji:
2005
Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Tematy:
Aqaba Gulf
biological stress
diffusion model
chlorophyll a
oligotrophic water
primary productivity
thermohaline stratification
nutrient flux
Red Sea
Opis:
The thermohaline characteristics of the Gulf of Aqaba, Red Sea, depict a welldefined seasonal pattern of winter mixing from December to April and summer stratification from May to November. This thermohaline structure is a major controlling factor of the nutrient, chlorophyll a and primary productivity seasonal cycles. The nitrate and chlorophyll a concentration records generated down to 200 m at a vertical resolution of 25 m – weekly during 1994, 1995 and every two weeks from April 1997 through to December 2000 – are employed to assess the nitrogen flux across the summer thermocline of the Gulf of Aqaba. The flux calculations are based on a simple diffusion model that incorporates the physical stress eddy diffusivity factor Kz and a biological stress factor k. Both Kz and k are calculated using the Michaelis-Menten equation and the nitrate concentration gradient. The total nitrate flux of the Gulf of Aqaba during the seven summer months (May–November) is estimated at 0.52 moleN m−2. In relation to established primary productivity values (75.5 gC m−2 (May November)−1) and the generated chlorophyll a records, this yields an f fraction of new to total primary production of 0.50. This relatively high f value is discussed with respect to the geophysical characteristics of the Gulf of Aqaba and similar oceanic basins. The remaining 50% is accounted for by cross-sectional flow from the relatively nutrientrich coral reef coastal habitat and rapid recycling, triggered by high irradiance and water temperature.
Źródło:
Oceanologia; 2005, 47, 1
0078-3234
Pojawia się w:
Oceanologia
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-4 z 4

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