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Wyszukujesz frazę "Mansour, S." wg kryterium: Autor


Wyświetlanie 1-7 z 7
Tytuł:
Effect of Doping by Different Transition Metals on the Acoustical Properties of Alkali Borate Glasses
Autorzy:
Gaafar, M.
El-Batal, F.
El-Gazery, M.
Mansour, S.
Powiązania:
https://bibliotekanauki.pl/articles/1808106.pdf
Data publikacji:
2009-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.43.Fs
43.35.Ae
62.20.Dc
65.40.De
Opis:
Longitudinal and shear ultrasonic wave velocities were measured in binary $Li_2O-2B_2O_3$ glasses doped with different transition metal oxides (TMOs) (where TMO = $V_2O_5$, $Fe_2O_3$, $Cr_2O_3$, NiO, $TiO_2$, $MnO_2$ and CuO) using pulse echo technique. Measurements were carried out at 4 MHz frequency and at room temperature. Elastic moduli and some other physical parameters such as acoustic impedance, Debye temperature, thermal expansion coefficient, and latent heat of melting were calculated. Results indicated that these parameters depend upon the TMO modifier i.e., the ionic radius of the transition metal cation. Quantitative analysis has been carried out, in order to obtain more information about the structure of these glasses, based on bond compression model, and the Makishima and Mackenzie model, i.e., the cation-anion bond of each TMO.
Źródło:
Acta Physica Polonica A; 2009, 115, 3; 671-678
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Biochemical, mineral and anatomical characteristics of the olive tree cv. Chetoui growing in several Tunisian areas
Autorzy:
Mansour-Gueddes, S.B.
Saidana, D.
Cheraief, I.
Dkhilali, M.
Braham, M.
Powiązania:
https://bibliotekanauki.pl/articles/12188720.pdf
Data publikacji:
2018
Wydawca:
Uniwersytet Przyrodniczy w Lublinie. Wydawnictwo Uniwersytetu Przyrodniczego w Lublinie
Tematy:
Tunisia
plant growing
Olea europaea
olive tree
Chetoui cultivar
plant cultivar
anatomical characteristics
biochemical characteristics
mineral content
volatile compound
growing condition
stress condition
Opis:
To tolerate harsh climatic conditions, olive tree Chetoui has developed some anatomic, physiologic and biochemical mechanisms. The aim of this study was to determine the indicators of stress in leaves, stems and roots growing under various climatic conditions. To protect against stress conditions this cultivar increased cuticle thickness, protective structures and building parenchyma tissues of leaves, woods and roots from the North to the South. The volatile compounds, extracted from northern and southern Chetoui leaves and roots, were analyzed by GC-FID and GC-MS. Great changes in volatiles were illustrated in the studied organs, by enrichment in phenolics and fatty acids for leaves and in hydrocarbons for roots of southern Chetoui. Also, a reduction in terpenes, alcohols and carbonylic compounds was noted in both southern samples. Moreover, minerals of all organs of Chetoui, varied in content and allocation, but their levels are the highest in leaves. The changes in volatiles might be affected by changes in the mineral elements uptake or accumulation under environment stress. A significant correlation was noted between phenolic compounds and sodium, nitrogen, and calcium contents. However, terpenoids was highly correlated with phosphorus content for all organs and studied areas. The detection of new volatiles, anatomical and mineral changes seem to be efficient indicators of adaptation of Chetoui to environment stress conditions.
Źródło:
Acta Scientiarum Polonorum. Hortorum Cultus; 2018, 17, 2; 49-70
1644-0692
Pojawia się w:
Acta Scientiarum Polonorum. Hortorum Cultus
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Chemical composition and biological activities assessment of olive fruit volatiles from different varieties grown in Tunisia
Autorzy:
Mansour-Gueddes, S.B.
Saidana, D.
Jabnoun-Khiareddine, H.
Bchir, A.
Daami-Remadi, M.
Braham, M.
Powiązania:
https://bibliotekanauki.pl/articles/12702502.pdf
Data publikacji:
2020
Wydawca:
Uniwersytet Przyrodniczy w Lublinie. Wydawnictwo Uniwersytetu Przyrodniczego w Lublinie
Opis:
Volatile compounds, present in olives, are responsible for the olive fruit flavor and oil aroma, influencing the consumer’s preference. These compounds have a biological activity to fight off pathogens. The aim of this work is to characterize volatiles in pulps and cores of Chemlali, Arbequina and Koroneiki olives, collected from Menzel Mhiri-Kairouan, and to test both the efficiency of these compounds against two bacteria and six phytopathogenic fungal species, by diffusion and dilution methods, and their antioxidants activities. The analyzis of volatiles were determined by GC-FID and GC-MS in three cultivars at the full ripening stage. Thirty five compounds were identified, such us an assortment of phenol, alcohol, hydrocarbon, aldehyde and terpenes derivatives. A high changes in volatiles was noted between cultivars and fruit organs. In fact, the major compounds in the pulps and the cores, of different cultivars, are (E)-2-decenal (46.9%), nonanal (19.6%), 1-hexadecene (16.3%), 7-methyl-1,3,5-cycloheptatriene 7-methyl-1,3,5-cycloheptatriene (15.47%), (E,E)-2,4-decadienal (14.5%) and 1-tetradecene (14.6%). Also, the cores volatiles illustrated more richness in aldehydes than the pulps for all cultivars. Volatile fractions exhibited a moderate to important antibacterial activities against bacteria. However, Arbequina cores volatiles and both Chemlali and Koroneiki pulps volatiles established a moderate to higher activities against tested fungi. The DPPH and ABTS˙⁺ tests demonstrated that the highest antioxidant capacity of volatiles were assigned to Arbequina cores and Koroneiki pulps. The Principal Components Analysis showed a significant relationship between antioxidants and/or antimicrobial properties and the levels of the main volatile compounds (limonene, methyldecane, nonanal, E-2-decenal, camphor, geranic acid, tetradecene, hexadecane, tetradecane) in different fruit organs.
Źródło:
Acta Scientiarum Polonorum. Hortorum Cultus; 2020, 19, 4; 3-20
1644-0692
Pojawia się w:
Acta Scientiarum Polonorum. Hortorum Cultus
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Performance analysis of DFT-S-OFDM waveform for Li-Fi systems
Autorzy:
Hussin, S.
Shalaby, E. Mansour
Powiązania:
https://bibliotekanauki.pl/articles/2063891.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Stowarzyszenie Elektryków Polskich
Tematy:
light-fidelity
visible light communications
orthogonal frequency division multiplexing
discrete Fourier transform spread
peak-to-average power ratio
Opis:
In this paper, the effect of an indoor visible light communication channel is studied. Moreover, the analysis of the received power distribution of the photodiode in the line of sight and the first reflection of the channel without line of sight with several parameters is simulated. Two different waveforms are explained in detail. Orthogonal frequency division multiplexing has been widely adopted in radio frequency and optical communication systems. One of the most important disadvantages of the orthogonal frequency division multiplexing signal is the high peak-to-average power ratio. Therefore, it is important to minimize the peak-to-average power ratio in the visible light communication systems more than in radio-frequency wireless applications. In the visible light communication systems, the high peak-to-average power ratio produces a high DC bias which reduces power efficiency of the system. A discrete Fourier transform spread orthogonal frequency division multiplexing is proposed to be used in wireless communication systems; its ability to minimize peak-to-average power ratio has been tested. The analysis of two different subcarrier allocation methods for the discrete Fourier transform-spread subcarriers, as well as the examination of two distinct subcarrier allocation strategies, distributed and localized mapping, are investigated and studied. The effects of an accurate new sub-band mapping for the localized discrete Fourier transform spread orthogonal frequency division multiplexing scheme are presented in this paper. The light-fidelity system performance of the orthogonal frequency division multiplexing and discrete Fourier transform spread orthogonal frequency division multiplexing with different sub-mapping techniques are simulated with Matlab™. A system performance size of bit error rate and peak-to-average power ratio are obtained, as well.
Źródło:
Opto-Electronics Review; 2021, 29, 4; 167--174
1230-3402
Pojawia się w:
Opto-Electronics Review
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Performance evaluation of UFMC-based VLC systems using a modified SLM technique
Autorzy:
Mansour Shalaby, E.
Dessouky, M.
Hussin, S.
Powiązania:
https://bibliotekanauki.pl/articles/1818194.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Stowarzyszenie Elektryków Polskich
Tematy:
universal filtered multi-carrier
orthogonal frequency division
multiplexing
peak-to-average power ratio
selected-mapping
discrete Hartley transform precoding
Opis:
Universal filtered multi-carrier (UFMC) is being studied as the favourable waveforms supporting the visible light communication broadcasting systems. However, the UFMC system faces a serious performance degradation on the transmitter side due to its high peak-to-average power ratio (PAPR). High PAPR of the signal is an analytical intention parameter for mobile networks, and it is necessary to minimize it as much as possible. This paper focuses on the PAPR reduction of the UFMC scheme. An efficient hybrid method of the PAPR reduction has been proposed and analysed through the Matlab™ simulation. The proposed hybrid scheme consists of a mixture of the selected-mapping method and the discrete Hartley transform precoding for a UFMC system (SLM-DHT-P-UFMC). The simulation results show that the proposed hybrid system has a better PAPR reduction performance compared to traditional SLM-UFMC and DHT-P-UFMC systems. Hence, LM-DHT-P-UFMC is considered to be the suggested scheme in visible light communication broadcasting systems.
Źródło:
Opto-Electronics Review; 2021, 29, 3; 85--90
1230-3402
Pojawia się w:
Opto-Electronics Review
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Performance evaluation of UFMC-based VLC systems using a modified SLM technique
Autorzy:
Mansour Shalaby, E.
Dessouky, M.
Hussin, S.
Powiązania:
https://bibliotekanauki.pl/articles/1818201.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Stowarzyszenie Elektryków Polskich
Tematy:
universal filtered multi-carrier
orthogonal frequency division
multiplexing
peak-to-average power ratio
selected-mapping
discrete Hartley transform precoding
Opis:
Universal filtered multi-carrier (UFMC) is being studied as the favourable waveforms supporting the visible light communication broadcasting systems. However, the UFMC system faces a serious performance degradation on the transmitter side due to its high peak-to-average power ratio (PAPR). High PAPR of the signal is an analytical intention parameter for mobile networks, and it is necessary to minimize it as much as possible. This paper focuses on the PAPR reduction of the UFMC scheme. An efficient hybrid method of the PAPR reduction has been proposed and analysed through the Matlab™ simulation. The proposed hybrid scheme consists of a mixture of the selected-mapping method and the discrete Hartley transform precoding for a UFMC system (SLM-DHT-P-UFMC). The simulation results show that the proposed hybrid system has a better PAPR reduction performance compared to traditional SLM-UFMC and DHT-P-UFMC systems. Hence, LM-DHT-P-UFMC is considered to be the suggested scheme in visible light communication broadcasting systems.
Źródło:
Opto-Electronics Review; 2021, 29, 3; 85--90
1230-3402
Pojawia się w:
Opto-Electronics Review
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Engineering effect of Pinna nobilis shells on benthic communities
Autorzy:
Rabaoui, L.
Belgacem, W.
Ben Ismail, D.
Mansour, L.
Tlig-Zouari, S.
Powiązania:
https://bibliotekanauki.pl/articles/47447.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Tematy:
Pinna nobilis
shell
ecosystem
restoration
conservation
benthic community
Źródło:
Oceanologia; 2015, 57, 3
0078-3234
Pojawia się w:
Oceanologia
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-7 z 7

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