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Wyświetlanie 1-5 z 5
Tytuł:
Structural Analysis of Ce Doped $La_{1-x}Sr_xCo_{1-y}Fe_yO_{3-δ}$ Nanopowders Synthesized by Glycine-Nitrate Gel Combustion
Autorzy:
Yildiz, Ö.
Soydan, A.
Ata, A.
İpçızade, E.
Akin, D.
Uçak, Ö.
Powiązania:
https://bibliotekanauki.pl/articles/1312023.pdf
Data publikacji:
2014-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.07.Wx
81.07.-b
81.20.Ka
88.30.pn
Opis:
Ce doped $La_{1-x}Sr_xCo_{1-y}Fe_yO_3$ (LCSCF) is a widely used cathode material due to its high catalytic activity for oxygen reduction and high oxygen exchange coefficient. LCSCF is also known with its high ionic and electronic conductivities and low electrode polarization losses which are highly critical properties for low temperature solid oxide fuel cell applications. In this study, structural properties of the LCSCF cathode nanopowder materials synthesized by glycine-nitrate gel combustion have been investigated by X-ray diffraction, differential scanning calorimetry, scanning electron microscopy, and nanosizer. Synthesized nanopowders represent volcanic ash like structures and morphologies. Ce, Sr, Co, and Fe are found to have significant effects on the structural properties of powders in terms of powders morphology, agglomerate structure, crystallite size and also lattice parameter of perovskite crystal. All synthesized ash powders have particle sizes around 50-600 nm, varying crystalline structures of perovskite and fluorite depending on molar ratio of Ce in the composition. Increasing molar Ce ratio over 0.4 is found to lead to the formation of a separate nano ceria phase in fluorite crystal structure on the surface of the synthesized powder.
Źródło:
Acta Physica Polonica A; 2014, 125, 2; 669-672
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Properties of Ceria Based Novel Anode Nanopowders Synthesized by Glycine-Nitrate Process
Autorzy:
Yıldız, Ö.
Soydan, A.
Ata, A.
Tunaboylu, B.
Akın, D.
İpcizade, E.
Powiązania:
https://bibliotekanauki.pl/articles/1399974.pdf
Data publikacji:
2013-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
82.47.Ed
81.07.Wx
81.20.Ka
81.20.Ev
81.05.Mh
61.46.Df
Opis:
Novel anode nanopowder materials consisting of ceria-based components synthesized by glycine-nitrate process were investigated for solid oxide fuel cells. Glycine-nitrate process involves a self-combustion reaction at 220C of water-based nitrate and glycine solutions which subsequently can reach up to 1200°C. The resulting morphology, the size of particles and the formation of crystalline phases were characterized by differential scanning calorimetry, X-ray diffraction, transmission electron microscopy, scanning electron microscopy, the Brunauer-Emmett-Teller method and Nanosizer. It was determined that dopants in ceria such as Co, Ni, Cu, V and Fe had significant effect on the morphology and size. The size distribution measured by Nanosizer was 50-600 nm, transmission electron microscopy, 5-200 nm and the Brunauer-Emmett-Teller method 100-120 nm and specific surface area of powders in the range 67.45-72.05 $m^2 g^{-1}$ as measured by the Brunauer-Emmett-Teller method. Particles were observed to have spherical structures for Cu and Fe doped powders and rod-shaped in a porous tuff microstructure for those doped with Co and Ni. Vanadium doping helped to decrease the porosity and initiated the process of spheroidization of particles.
Źródło:
Acta Physica Polonica A; 2013, 123, 2; 432-435
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Air Quality Assessment and Forecasting Using Neural Network Model
Autorzy:
Hamdan, Mohammad A.
Ata, Mohammad F. Bani
Sakhrieh, Ahmad H.
Powiązania:
https://bibliotekanauki.pl/articles/1838288.pdf
Data publikacji:
2021
Wydawca:
Polskie Towarzystwo Inżynierii Ekologicznej
Tematy:
air pollutant
ANN
MATLAB
forecasting
Opis:
Air pollution is a major obstacle faced by all countries which impacts the environment, public health, socioeconomics, and agriculture. In this study, the air pollutants in the city of Amman were presented and analyzed. Nonlinear Autoregressive Exogenous (NARX) model was used to forecast the daily average levels of pollutants in Amman, Jordan. The model was built using the MATLAB software. The model utilized a Marquardt-Levenberg learning algorithm. Its performance was presented using different indices, R2 (Coefficient of Determination), R (Coefficient of Correlation), NMSE (Normalized Mean Square Error), and Plots representing network predictions vs original data. Historical measurements of air pollutants were obtained from 4 of the Ministry of Environment (MoEnv) air quality monitoring stations in Amman. The meteorological data representing three years (2015, 2016, and 2017) were used as predictors to train the Artificial Neural Network (ANN) while the data of the year 2018 were used to test it. The results showed good performance when forecasting SO2, O3, CO, and NO2, and acceptable performance when forecasting Particulate Matter (PM10) at the given 4 locations.
Źródło:
Journal of Ecological Engineering; 2021, 22, 6; 1-11
2299-8993
Pojawia się w:
Journal of Ecological Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Air Quality Assessment and Forecasting Using Neural Network Model
Autorzy:
Hamdan, Mohammad A.
Ata, Mohammad F. Bani
Sakhrieh, Ahmad H.
Powiązania:
https://bibliotekanauki.pl/articles/1838392.pdf
Data publikacji:
2021
Wydawca:
Polskie Towarzystwo Inżynierii Ekologicznej
Tematy:
air pollutant
ANN
MATLAB
forecasting
Opis:
Air pollution is a major obstacle faced by all countries which impacts the environment, public health, socioeconomics, and agriculture. In this study, the air pollutants in the city of Amman were presented and analyzed. Nonlinear Autoregressive Exogenous (NARX) model was used to forecast the daily average levels of pollutants in Amman, Jordan. The model was built using the MATLAB software. The model utilized a Marquardt-Levenberg learning algorithm. Its performance was presented using different indices, R2 (Coefficient of Determination), R (Coefficient of Correlation), NMSE (Normalized Mean Square Error), and Plots representing network predictions vs original data. Historical measurements of air pollutants were obtained from 4 of the Ministry of Environment (MoEnv) air quality monitoring stations in Amman. The meteorological data representing three years (2015, 2016, and 2017) were used as predictors to train the Artificial Neural Network (ANN) while the data of the year 2018 were used to test it. The results showed good performance when forecasting SO2, O3, CO, and NO2, and acceptable performance when forecasting Particulate Matter (PM10) at the given 4 locations.
Źródło:
Journal of Ecological Engineering; 2021, 22, 6; 1-11
2299-8993
Pojawia się w:
Journal of Ecological Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Physical restrictions of the flotation of fine particles and ways to overcome them
Autorzy:
Karakashev, Stoyan I.
Grozev, Nikolay A
Ozdemir, Orhan
Guven, Onur
Ata, Seher
Bournival, Ghislain
Batjargal, Khandjamts
Boylu, Feridun
Hristova, Svetlana
Çelik, Mehmet Sabri
Powiązania:
https://bibliotekanauki.pl/articles/2146879.pdf
Data publikacji:
2022
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
fine particle flotation
frequency of collisions
surface force manipulation
thin wetting films
Opis:
This work analyses the basic problems of the fine particles flotation and suggests new ways to overcome them. It is well accepted that the poor recovery of fine particles is due to the small collision rate between them and the bubbles due to the significant difference between their sizes. This common opinion is based on a theory, assuming in its first version a laminar regime, but later has been advanced to intermediate turbulence. It accepts that the particles are driven by the streamlines near the bubbles. In reality, the high turbulence in the flotation cells causes myriads of eddies with different sizes and speeds of the rotation driving both bubbles and particles. Yet, a theory accounting for high turbulence exists and states that the collision rate could be much higher. Therefore, we assumed that the problem consists of the low attachment efficiency of the fine particles. Basically, two problems could exist (i) to form a three-phase contact line (TPCL) the fine particle should achieve a certain minimal penetration into the bubble, requiring sufficient push force; (ii) a thin wetting film between the bubble and the particle forms, thus increasing the hydrodynamic resistance between them and making the induction time larger than the collision time. We assumed particles with contact angle θ = 80°, and established a lower size flotation limit of the particles depending mostly on the size of the bubbles, with which they collide. It spans in the range of Rp = 0.16 um to Rp = 0.40 um corresponding to bubbles size range of Rb = 50 um to Rb = 1000 um. Hence, thermodynamically the particle size fraction in the range of Rp = 0.2 um to Rp = 2 um are permitted to float but with small flotation rate due to the small difference between the total push force and maximal resistance force for formation of TPCL. The larger particles approach slowly the bubbles, thus exceeding the collision time. Therefore, most possibly the cavitation of the dissolved gas is the reason for their attachment to the bubbles. To help fine particles float better, the electrostatic attraction between bubbles and particles occurred and achieved about 92% recovery of fine silica particles for about 100 sec. The procedure increased moderately their hydrophobicity from θ ≈ 27.4° to θ ≈ 54.5°. Electrostatic attraction between bubbles and particles with practically no increase of the hydrophobicity of the silica particles ended in 47% recovery. All this is an indication of the high collision rate of the fine particles with the bubbles. Consequently, both, an increase in the hydrophobicity and the electrostatic attraction between particles and bubbles are key for good fine particle flotation. In addition, it was shown experimentally that the capillary pressure during collision affected significantly the attachment efficiency of the particles to the bubbles.
Źródło:
Physicochemical Problems of Mineral Processing; 2022, 58, 5; art. no. 153944
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-5 z 5

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