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Tytuł:
Hopping Conductance in Nanocomposites $(Fe_{0.45}Co_{0.45}Zr_{0.10})_{x}(Al_2O_3)_{1 - x}$ Manufactured by Ion-Beam Sputtering of Complex Target in $Ar+O_2$ Ambient Gas
Autorzy:
Kołtunowicz, T.
Zhukowski, P.
Fedotova, V.
Saad, A.
Fedotov, A.
Powiązania:
https://bibliotekanauki.pl/articles/1503812.pdf
Data publikacji:
2011-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
79.20.Rf
73.22.-f
84.37.+q
72.20.Ee
Opis:
We report the investigation of a real part of the admittance σ of granular nanocomposites $(Fe_{0.45}Co_{0.45}Zr_{0.10})_{x}(Al_2O_3)_{1 - x}$ with 0.30 < x < 0.70 in the dielectric (hopping) regime. An analysis of the σ(T, f, x) dependences in the as-deposited and annealed films over the temperature 77 K < T < 300 K and frequency 50 < f < $10^6$ Hz ranges displayed the predominance of an activation (hopping) conductance mechanism with dσ/ dT > 0 for the samples below the percolation threshold $x_{C}$ ≈ 0.76 ± 0.05. Based on the earlier models for hopping AC conductance, computer simulation of the frequency coefficient $α_{f}$ of hopping conductance depending on the probability of jump p, frequency f, and also on the shape of σ(f) curve was performed. The experimental and simulation results revealed a good agreement.
Źródło:
Acta Physica Polonica A; 2011, 120, 1; 39-42
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Coffee grounds as a soil conditioner: effects on physical and mechanical properties - II. Effects on mechanical properties
Autorzy:
Bedaiwy, M.N.A.
Maksoud, Y.S.A.
Saad, A.F.
Powiązania:
https://bibliotekanauki.pl/articles/971314.pdf
Data publikacji:
2019
Wydawca:
Uniwersytet Marii Curie-Skłodowskiej. Wydawnictwo Uniwersytetu Marii Curie-Skłodowskiej
Tematy:
coffee grounds
mechanical properties
soil amendments
soil conditioners
Opis:
Applying coffee grounds (CG) to sandy, calcareous, and clayey soils resulted in notable effects on soil expansion, cracking, cohesion, internal friction, initial stress and resistance to penetration. In sand, expansion upon saturation was greater after wetting-and-drying cycles. Highest increases were 15.71%, 16.14% and 31.86% for sandy, calcareous and clayey soils, respectively. Effect of CG on cracking was negligible in sand and very slight (<1.0%) in the calcareous soil but marked in clay (14.18% at 10% CG). In sand, cohesion (c) increased significantly with CG up to the 10% content. Cohesion increased by 2.5-folds and 4.5-folds at 5% and 10% CG, respectively. The presence of fine CG grains among larger sand particles, boosted microbial activities, and the resulting cementing and binding effects resulted in increased cohesion. For calcareous soil, cohesion rose from 0.04 kg·cm⁻² to 0.13 kg·cm⁻² as CG increased from 0% to 15%. In clay, maximum cohesion (0.20 kg·cm⁻²) was associated with the 10% CG and was highest of all soils. In sand, the angle of internal friction (φ) decreased notably as CG increased from 5% to 10% but there was no consistent pattern in any of the soils. An increase in initial stress (pi) was observed between 0% and 10% CG in sand and between 0% and 15% in calcareous soil while clay showed no particular trend. Patterns of pi were, thus, consistent with those of cohesion for all soils. Resistance to penetration increased substantially with CG in sand. The effect in calcareous and clayey soils took an opposite trend to that of sand and resistance was generally higher in calcareous soil. Overall effects of CG on resistance were desirable in all soils as far as agriculture (seedling emergence, crop growth, irrigation, etc.) is concerned.
Źródło:
Polish Journal of Soil Science; 2019, 52, 2; 277-294
0079-2985
Pojawia się w:
Polish Journal of Soil Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Coffee Grounds as a Soil Conditioner: Effects on Physical and Mechanical Properties - I. Effects on Physical Properties
Autorzy:
Bedaiwy, M. Naguib A.
Abdel Maksoud, Y S
Saad, A F
Powiązania:
https://bibliotekanauki.pl/articles/762799.pdf
Data publikacji:
2018
Wydawca:
Uniwersytet Marii Curie-Skłodowskiej. Wydawnictwo Uniwersytetu Marii Curie-Skłodowskiej
Tematy:
coffee grounds
physical properties
soil amendments
soil conditioners
Opis:
Coffee grounds (CG) improved some soil physical properties (dry density, gd; porosity, n; aggregation; hydraulic conductivity, Ks; and infiltration rate, IR). Effects on other properties were inconsistent (e.g., sorptivity, S), or unfavorable (e.g., available water, AW). gd decreased and n increased with CG. CG decreased Ks in sand. In calcareous soil, maximum increase was associated with 10% and 15% CG before and after wetting-and-drying cycles (WDC), respectively. Ks increased with CG in clay, with greatest increase attained at 10% CG. IR decreased with CG in sand. In calcareous and clayey soils, IR decreased with CG before WDC but increased after WDC where maximum increase in clay was linked to 10% CG. No solid trends of soil sorptivity, S, were identified. Before WDC, S had the order: sand > calcareous > clay. For most cases, adding CG increased total water holding capacity (WHC). However, after WDC, the increase in water content at field capacity (FC) with CG was accompanied by a greater increase in wilting point (WP) and therefore a decrease in AW. CG improved soil structure and aggregation and increased non-water-stable aggregates in calcareous and clayey soils. Mean weight diameter (MWD) indicated increase in water-stable aggregates in sand at 5% and 10% CG. In clay, MWD increased only at 5% CG. Although results did not show coherent responses with some tested properties, they, mostly, indicate some beneficial effects of CG, particularly in relation to improving aggregation and water flow.
Źródło:
Polish Journal of Soil Science; 2018, 51, 2
0079-2985
Pojawia się w:
Polish Journal of Soil Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Features of Real Part of Admittance in the Nanocomposites $(Fe_{45}Co_{45}Zr_{10})_{x}(Al_2O_3)_{100 - x}$ Manufactured by the Ion-Beam Sputtering Technique with Ar Ions
Autorzy:
Kołtunowicz, T.
Zhukowski, P.
Fedotova, V.
Saad, A.
Larkin, A.
Fedotov, A.
Powiązania:
https://bibliotekanauki.pl/articles/1503798.pdf
Data publikacji:
2011-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
79.20.Rf
73.22.-f
84.37.+q
72.20.Ee
Opis:
The temperature and frequency dependences of the admittance real part σ (T, f) in granular $(Fe_{45}Co_{45}Zr_{10})_{x}(Al_2O_3)_{100 - x}$ nanocomposite films around the percolation threshold $x_{C}$ were investigated. The behaviour of σ (T, f) vs. the temperature and frequency over the ranges 77-300 K and 50 Hz-1 MHz, respectively, displays the predominance of an activation (hopping) conductance mechanism for the samples below the percolation threshold $x_{C}$ and of a metallic one beyond the $x_{C}$ determined as 54 ± 2 at.%. The mean hopping range d for the nanoparticles diameter D was estimated at different metallic phase content x.
Źródło:
Acta Physica Polonica A; 2011, 120, 1; 35-38
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Low-Temperature DC Carrier Transport in $(Co_{0.45}Fe_{0.45}Zr_{0.10})_{x}(Al_2O_3)_{1-x}$ Nanocomposites Sputtered in Mixed Argon-Oxygen Atmosphere
Autorzy:
Svito, I.
Fedotov, A.
Saad, A.
Koltunowicz, T.
Zukowski, P.
Bury, P.
Powiązania:
https://bibliotekanauki.pl/articles/1366313.pdf
Data publikacji:
2014-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.22.-f
72.20.Ee
64.60.ah
Opis:
This paper studies the temperature dependences (2 < T < 300 K) of the DC conductivity σ(T) for the $(Co_{0.45}Fe_{0.45}Zr_{0.10})_x(Al_2O_3)_{1-x}$ nanocomposites (30 < x < 65 at.%) sputtered in Ar + $O_2$ atmosphere. It is shown that at temperatures lower than 100-150 K dependences of DC conductance on temperature for all the studied samples are due to the Shklovski-Efros variable range hopping mechanism. It was also observed that σ(x,T) dependences can be attributed to the formation of FeCo-based oxide "shells" around metallic alloy nanoparticles due to incorporation of oxygen in the vacuum chamber during the deposition procedure.
Źródło:
Acta Physica Polonica A; 2014, 125, 6; 1351-1354
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mechanisms of Carrier Transport in $Cu_x(SiO_2)_{1-x}$ Nanocomposites Manufactured by Ion-Beam Sputtering with Ar Ions
Autorzy:
Fedotov, A.
Mazanik, A.
Svito, I.
Saad, A.
Fedotova, V.
Czarnacka, K.
Koltunowicz, T.
Powiązania:
https://bibliotekanauki.pl/articles/1402220.pdf
Data publikacji:
2015-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
84.37.+q
72.80.Ga
73.22.-f
61.46.Df
64.60.ah
Opis:
The present paper investigates the temperature/frequency dependences of admittance Z in the granular $Cu_x(SiO_2)_{1-x}$ nanocomposite films around the percolation threshold $x_{C}$ in the temperature range of 4-300 K and frequencies of 20-10⁶ Hz. The behavior of low-frequency ReZ(T) dependences displayed the predominance of electrons hopping between the closest Cu-based nanoparticles for the samples below the percolation threshold $x_{C}$ ≈ 0.59 and nearly metallic behaviour beyond the $x_{C}$. The high-frequency curves ReZ(f) at temperatures T > 10 K for the samples with x < $x_{C}$ exhibited behavior close to ReZ(f) ≈ $f^{-s}$ with s ≈ 1.0 which is very similar to the known Mott law for electron hopping mechanism. For the samples beyond the percolation threshold (x > $x_{C}$), the frequency dependences of ReZ(f) displayed inductive-like (not capacitive) behaviour with positive values of the phase shift angles.
Źródło:
Acta Physica Polonica A; 2015, 128, 5; 883-886
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Admittance and Permittivity in Doped Layered $TlGaSe_2$ Single Crystals
Autorzy:
Dawood, S.
Fedotov, A.
Mammadov, T.
Zukowski, P.
Koltunowicz, T.
Saad, A.
Drozdov, N.
Powiązania:
https://bibliotekanauki.pl/articles/1365735.pdf
Data publikacji:
2014-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.61.Ey
84.37.+q
64.70.Nd
Opis:
In doped $TlGaSe_2$ crystals the phase transitions at low temperatures (100-170 K) were observed using admittance and dielectric spectroscopy in a temperature range of 80-320 K. The admittance and permittivity measurements in the studied samples indicated that after Fe or Tb doping by impurities with concentrations $N_\text{imp}$ < 0.5 at.% nonequilibrium electronic phase transition is observed. Doping with $N_\text{imp}$ > 0.5 at.% resulted in full suppression of this phase transition presence.
Źródło:
Acta Physica Polonica A; 2014, 125, 6; 1267-1270
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Voltage and Current Resonance in Nanocomposite $(FeCoZr)_x(CaF_2)_{100-x}$ Produced by Ion-Beam Sputtering in Pure Argon Atmosphere
Autorzy:
Koltunowicz, T.
Zukowski, P.
Bondariev, V.
Fedotov, A.
Svito, I.
Fedotova, J.
Saad, A.
Powiązania:
https://bibliotekanauki.pl/articles/1402224.pdf
Data publikacji:
2015-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
62.23.Pq
79.20.Rf
81.40.Ef
72.80.Le
Opis:
In this paper the results of investigations of electrical properties of metal-dielectric nanocomposites $(FeCoZr)_x(CaF_2)_{100-x}$ are presented. The samples with the metallic phase content x=45.7 at.% were produced by ion-beam sputtering method in pure argon atmosphere, and subsequently annealed at 398 K for 15 min. The measurements of electrical properties were performed in the frequency range from 50 Hz to 1 MHz. The frequency dependences of phase angle θ, capacity $C_{p}$, conductivity σ and dielectric loss factor tanδ were measured at seven different temperatures ranging from 148 K to 263 K. It was found that the nanocomposite exhibits the phenomena of voltage resonance and current resonance, characteristic of the conventional RLC circuits with series and parallel connections of elements.
Źródło:
Acta Physica Polonica A; 2015, 128, 5; 897-900
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Story Point Estimation Using Issue Reports With Deep Attention Neural Network
Autorzy:
Kassem, Haithem
Mahar, Khaled
Saad, Amani A.
Powiązania:
https://bibliotekanauki.pl/articles/2203950.pdf
Data publikacji:
2023
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
story points
deep learning
glove
hierarchical attention networks
agile
planning poker
Opis:
Background: Estimating the effort required for software engineering tasks is incredibly tricky, but it is critical for project planning. Issue reports are frequently used in the agile community to describe tasks, and story points are used to estimate task effort. Aim: This paper proposes a machine learning regression model for estimating the number of story points needed to solve a task. The system can be trained from raw input data to predict outcomes without the need for manual feature engineering. Method: Hierarchical attention networks are used in the proposed model. It has two levels of attention mechanisms implemented at word and sentence levels. The model gradually constructs a document vector by grouping significant words into sentence vectors and then merging significant sentence vectors to create document vectors. Then, the document vectors are fed into a shallow neural network to predict the story point. Results: The experiments show that the proposed approach outperforms the state-of-the-art technique Deep-S which uses Recurrent Highway Networks. The proposed model has improved Mean Absolute Error (MAE) by an average of 16.6% and has improved Median Absolute Error (MdAE) by an average of 53%. Conclusion: An empirical evaluation shows that the proposed approach outperforms the previous work.
Źródło:
e-Informatica Software Engineering Journal; 2023, 17, 1; art. no. 230104
1897-7979
Pojawia się w:
e-Informatica Software Engineering Journal
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Assessment of the risk for human health of Enterovirus and Hepatitis A virus in clinical and water sources from three metropolitan cities of Pakistan
Autorzy:
Ahmad, T.
Adnan, F.
Nadeem, M.
Kakar, S.J.
Anjum, S.
Saad, A.
Waheed, A.
Arshad, N.
Powiązania:
https://bibliotekanauki.pl/articles/2081926.pdf
Data publikacji:
2018
Wydawca:
Instytut Medycyny Wsi
Tematy:
epidemiology
Enterovirus (EntV)
HAV
PCR
virology
Opis:
Introduction. Molecular studies have confirmed the silent circulation of enterovirus (EntV) and hepatitis A virus in the environment, even in the absence of clinical manifestation. Viral pathogens are among the major causes of disease outbreaks, particularly in the bigger cities and both in the developed and underdeveloped nations. Materials and method. Between June 2016 – June 2017, 97 samples of drinking water, river water polluted with sewage and blood were selected and obtained from high risk communities in Pakistan. Negatively charged membrane filters were used to concentrate the virus, followed by the use of specific PCR primers set for quick identification of the waterborne viruses. Results. Enteroviruses were recovered from 40%, 28.57% and 33.33% of river water polluted with sewage samples in Lahore, Islamabad and Rawalpindi, respectively, while the presence of 13.13% and 11.76% of viral load was also confirmed in the drinking water of Lahore and Rawalpindi, respectively. A high prevalence of HAV (12.5% and 21.05%) was also verified in the clinical samples. Phylogenetic analysis indicated close resemblance of HAV isolates with the Indian strains. This study is the first ever comparative analysis of the EntV and HAV isolated from environmental samples and clinical specimen on a molecular level. Conclusions. The parallel surveillance of EntV and HAV in the river water polluted with sewage, and clinical samples is quite helpful for controlling and reducing the disease burden of the waterborne illnesses.
Źródło:
Annals of Agricultural and Environmental Medicine; 2018, 25, 4; 708-713
1232-1966
Pojawia się w:
Annals of Agricultural and Environmental Medicine
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-10 z 28

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