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Wyszukujesz frazę "Khan, Asif" wg kryterium: Autor


Wyświetlanie 1-3 z 3
Tytuł:
Experimental and numerical determination of apparent mass variation of granular media confined in silo geometry
Autorzy:
Qadir, Abdul
Ispalove, Nurlybek
Ali, Asim
Chand, R.
Shah, M.
Khan, Asif
Hussain, Kashif
Powiązania:
https://bibliotekanauki.pl/articles/1070521.pdf
Data publikacji:
2016-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
83.80.Fg
45.70.Cc
45.70.-n
Opis:
Granular materials have vast applications both in industry and in daily life. They display quite interesting and exceptional properties different from the other known forms of matter. To investigate the complex properties of particulate materials, experimental, analytical, and numerical techniques have been employed. In this paper the results of experimental and numerical tests of various grain sizes and coefficient of friction between granules and cylindrical walls on the mass measured at bottom of container, known as apparent mass, are reported. It is revealed that apparent mass augments with the grain size. Moreover, it is also found that the variation in apparent mass measurement is strongly dependent on bead diameter rather than the silo size. The results suggest that the conversion of vertical stresses into horizontal in silo is mainly due to the friction between the grain and system boundary than the arching phenomenon.
Źródło:
Acta Physica Polonica A; 2016, 129, 3; 378-382
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Luminescence of Highly Excited Nonpolar a-Plane GaN and AlGaN/GaN Multiple Quantum Wells
Autorzy:
Juršėnas, S.
Kuokštis, E.
Miasojedovas, S.
Kurilčik, G.
Žukauskas, A.
Chen, C. Q.
Yang, J. W.
Adivarahan, V.
Asif Khan, M.
Powiązania:
https://bibliotekanauki.pl/articles/2038100.pdf
Data publikacji:
2004-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.55.Cr
73.21.Fg
72.20.Jv
78.47.+p
Opis:
Carrier recombination dynamics in polar and nonpolar GaN epilayers and GaN/AlGaN multiple quantum wells grown over sapphire substrates with various crystallographic orientation were studied under high photoexcitation by 20 ps laser pulses. The transient of luminescence featured a significant enhancement in nonradiative recombination of free carriers for nonpolar a-plane GaN epilayers compared to conventional c-plane samples. The epitaxial lateral overgrowth technique was demonstrated to significantly improve the quality of nonpolar a-plane films. This was proved by more than 40-fold increase in luminescence decay time (430 ps compared to ≤10 ps in the ordinary a-plane epilayer). Under high-excitation regime, a complete screening of built-in electric field by free carriers in multiple quantum wells grown on c-plane and r-plane sapphire substrates was achieved. Under such high excitation, luminescence efficiency and carrier lifetime of multiple quantum wells was shown to be determined by the substrate quality.
Źródło:
Acta Physica Polonica A; 2004, 105, 6; 567-573
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Luminescence of Highly Photoexcited GaN Epilayers and Heterostructures Grown on Different Sapphire Crystal Planes
Autorzy:
Juršėnas, S.
Miasojedovas, S.
Kurilčik, G.
Liuolia, V.
Žukauskas, A.
Chen, C. Q.
Yang, J. W.
Kuokštis, E.
Adivarahan, V.
Asif Khan, M.
Powiązania:
https://bibliotekanauki.pl/articles/2041736.pdf
Data publikacji:
2005-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.55.Cr
73.21.Fg
72.20.Jv
78.47.+p
Opis:
GaN epilayers and AlGaN/GaN multiple quantum wells grown by metalorganic chemical vapor deposition on different crystal planes (c, a, and r) of the sapphire substrate were studied by excitation intensity dependent and time-resolved photoluminescence. In polar multiple quantum wells grown on a- and c-planes, a blueshift of the luminescence band with increasing the excitation energy was observed, indicating that screening of built-in field by free carriers takes place, whereas in nonpolar r-plane grown multiple quantum wells, the luminescence band maintained an almost constant peak position. Full screening of built-in field was achieved at the excitation densities higher than 0.3 mJ/cm$\text{}^{2}$. Under conditions of screened built-in electric field the structures were characterized by carrier lifetime. It was shown that nonpolar multiple quantum wells suffer from high density of nonradiative traps that can be due to substrate related threading dislocations.
Źródło:
Acta Physica Polonica A; 2005, 107, 2; 235-239
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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