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Wyszukujesz frazę "Afifi, M. A." wg kryterium: Autor


Wyświetlanie 1-5 z 5
Tytuł:
Effect of Annealing on the AC Conductivity and the Dielectric Properties of In$\text{}_{2}$Te$\text{}_{3}$ Thin Films
Autorzy:
Afifi, M. A.
Abd El-Wahabb, E.
Bekheet, A. E.
Atyia, H. E.
Powiązania:
https://bibliotekanauki.pl/articles/2014347.pdf
Data publikacji:
2000-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
77.55.+f
72.20.-i
Opis:
In$\text{}_{2}$Te$\text{}_{3}$ thin films were prepared by thermal evaporation technique. The composition of the films is checked by energy dispersive X-ray analysis. X-ray analysis showed that the as-deposited In$\text{}_{2}$Te$\text{}_{3}$ films as well as films annealed at temperatures ≤473K have crystalline structure. The ac conductivity σ$\text{}_{ac}$(ω), the dielectric constant ε$\text{}_{1}$ and the dielectric loss ε$\text{}_{2}$ of In$\text{}_{2}$Te$\text{}_{3}$ films were studied in the temperature range 303-373K and in the frequency range 100Hz-100kHz. The ac conduction activation energy ΔE$\text{}_{σ}$(ω) was found to be 0.065eV for the as-deposited films. The ac conductivity was found to obey the relation σ$\text{}_{ac}$(ω)=Aω$\text{}^{s}$, where s is the frequency exponent. The obtained temperature dependence of s is reasonably interpreted by quantum mechanical tunneling model. Both the dielectric constant ε$\text{}_{1}$ and the dielectric loss ε$\text{}_{2}$ increased with temperature and decreased with frequency in the investigated range. The frequency and temperature dependencies of σ$\text{}_{ac}$(ω), ε$\text{}_{1}$, and ε$\text{}_{2}$ for the annealed samples have the same behavior as that for the as-deposited samples. However, values of σ$\text{}_{ac}$(ω), ε$\text{}_{1}$, and ε$\text{}_{2}$ measured at any frequency and temperature increased with annealing temperature up to 473K. It was found also that ΔE$\text{}_{σ}$(ω) decreased with annealing temperature.
Źródło:
Acta Physica Polonica A; 2000, 98, 4; 401-409
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electrical and Dielectric Properties of Amorphous Ge$\text{}_{1}$Se$\text{}_{1.35}$TL$\text{}_{0.1}$ Films
Autorzy:
Abdel-Aziz, M. M.
Afifi, M. A.
Labib, H. H.
El-Metwally, E. G.
Powiązania:
https://bibliotekanauki.pl/articles/2014346.pdf
Data publikacji:
2000-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.80.Ng
72.20.-i
Opis:
The temperature dependence of the DC and AC electrical conductivity were measured for Ge$\text{}_{1}$Se$\text{}_{1.35}$Tl$\text{}_{0.1}$ films. The value of DC electrical conduction energy ΔE$\text{}_{σ}$ does not depend on film thickness in the investigated range with mean value of 0.72eV. The AC conductivity σ$\text{}_{AC}$ is related to frequency by the expression σ$\text{}_{AC}$=Aω$\text{}^{S}$, where S is the frequency exponent which decreases linearly with increasing temperature. This can be explained in terms of the pair (bipolaron) correlated barrier hopping model suggested by Elliott. The frequency and temperature dependence of real and imaginary parts of the dielectric constant were studied for Ge$\text{}_{1}$Se$\text{}_{1.35}$Tl$\text{}_{0.1}$ films. The dielectric constant (real part) and the dielectric loss (imaginary part) increase with increasing temperature and decrease with increasing frequency in the investigated range of frequency and temperature. The maximum barrier height W$\text{}_{M}$ can be calculated according to the Giuntini equation at different temperatures. The obtained value of W$\text{}_{M}$ is in good agreement with the theory of hopping of charge carriers over a potential barrier as suggested by Elliott in case of chalcogenide glasses.
Źródło:
Acta Physica Polonica A; 2000, 98, 4; 393-399
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Regional Detection and Reconstruction of Unknown Internal or Boundary Sources
Autorzy:
Afifi, L.
El Jai, A.
Merry, M.
Powiązania:
https://bibliotekanauki.pl/articles/908333.pdf
Data publikacji:
2001
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
plik źródłowy
czujnik pomiarowy
sources
detection
observation
region
sensors
Opis:
The purpose of this paper is to study the problem of regional detection, to characterize internal or boundary regionally detectable sources and regionally spy sensors, and to establish a relationship between these sensors and regionally strategic sensors. It is shown how to reconstruct a regionally detectable internal or a boundary source from a given output, with an extension to the case when the output is affected by an observation error. Numerical results are given in the case of a diffusion system.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2001, 11, 2; 319-347
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Weak and exact domination in distributed systems
Autorzy:
Afifi, L.
Magri, E. M.
El Jai, A.
Powiązania:
https://bibliotekanauki.pl/articles/907699.pdf
Data publikacji:
2010
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
system rozproszony
dominacja
aktuator
czujnik
distributed system
domination
actuators
sensors
Opis:
In this work, we introduce and examine the notion of domination for a class of linear distributed systems. This consists in studying the possibility to make a comparison between input or output operators. We give the main algebraic properties of such relations, as well as characterizations of exact and weak domination. We also study the case of actuators, and various situations are examined. Applications and illustrative examples are also given. By duality, we extend this study to observed systems. We obtain similar results and properties, and the case of sensors is equally examined.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2010, 20, 3; 419-426
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
PCR-based detection of Helicobacter pylori and non-Helicobacter pylori species among humans and animals with potential for zoonotic infections
Autorzy:
Youssef, A.I.
Afifi, A.
Abbadi, S.
Hamed, A.
Enany, M.
Powiązania:
https://bibliotekanauki.pl/articles/2087111.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Helicobacter spp.
zoonotic infections
detection
identification
Źródło:
Polish Journal of Veterinary Sciences; 2021, 24, 3; 445-450
1505-1773
Pojawia się w:
Polish Journal of Veterinary Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-5 z 5

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