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RISS 인기검색어
- 검색키워드
- 저자 : Hamzawy, A. (검색결과 3 건)
- 무료
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Thabet, Abouzeid A.,Hamzawy, A.,Badawi, Mohamed S. Korean Nuclear Society 2020 Nuclear Engineering and Technology Vol.52 No.6
The geometrical efficiency of a source-to-detector configuration is considered to be necessary in the calculation of the full energy peak efficiency, especially for NaI(Tl) and HPGe gamma-ray spectroscopy detectors. The geometrical efficiency depends on the solid angle subtended by the radioactive sources and the detector surfaces. The present work is basically concerned to establish a new mathematical approach for calculating the solid angle and geometrical efficiency, based on conversion of the geometrical solid angle of a non-axial radioactive point source with respect to a circular surface of the detector to a new equivalent geometry. The equivalent geometry consists of an axial radioactive point source with respect to an arbitrary elliptical surface that lies between the radioactive point source and the circular surface of the detector. This expression was extended to include coaxial radioactive circular disk source. The results were compared with a number of published data to explain how significant this work is in the efficiency calibration procedure for the γ-ray detection systems, especially in case of using isotropic radiating γ-ray sources in the form of point and disk shapes.
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Samah S. Eldera,Reem Al-wafi,Omar A. Al-Harbi,Christian Rüssel,Esmat M. A. Hamzawy 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.11
A porous glass-ceramic enjoyed very low and negative thermal expansion was prepared. A glass of the base molar composition, 2 MgO·2 Al 2 O 3 ·2 B 2 O 3 ·5 SiO 2 with the addition of 1.61 ma% TiO 2 , was melted from kaolin, magnesite, silica sand and boric acid. The composition is based on cordierite where 50 % Al 2 O 3 were replaced by an equimolar concentration of B 2 O 3 . The glass was crashed and powdered, subsequently plastified, uniaxially pressed and finally sintered at temperatures in the range from 1100 to 1300 °C. X-ray diffraction of sintered samples gave evidence of a cordierite like crystalline phase. Scanning electron microscopy and electron dispersive microanalysis of samples prepared at 1300 °C showed crystals with hexagonal shape doped by TiO 2 , B 2 O 3 and Fe 2 O 3 embedded in a glassy matrix. With increasing crystallization temperature, the porosity of the glass-ceramics increased from 8.99 % (at 1200 °C for 3 min) to 56.42 % (at 1300 °C for 3 min). This led to a decrease of the specimen density from 1.9880 to 1.1278 g/cm 3 whereas the skeletal density increased from 2.1303 g/cm 3 to 2.5878 g/cm 3 . The microhardnesses were in the 5.60 and 6.00 GPa range. The coefficient of thermal expansion was between -3.26 and -2.27x10 -6 K -1 from room temperature up to 300 o C and -0.45 and 1.89x10 -6 K -1 from room temperature up to 500 °C. For the first time, to the best of our knowledge, a porous cordierite glass-ceramic with negative thermal expansion is reported. The partial replacement of Al 2 O 3 by B 2 O 3 enables to apply lower melting temperature which is advantageous for the production process.
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Shorouk Hamzawi,Qing Shan Ding,Hanqun Song 글로벌지식마케팅경영학회 2023 Global Marketing Conference Vol.2023 No.07
By merging Bourdieu's cultural capital with self-determination theory, this study aims to better understand smoking cessation behaviour in Egypt. The results demonstrate that the accumulation of cultural capital satisfies three fundamental needs, contributes to the self-determination theory's motivating forms, and serves as an independent cause for smoking cessation in Egypt.
ScienceON
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