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1.
Summary In real systems there is always a certain amount of slip, which, however, is hard to detect experimentally because of the
required space resolution. In this paper, we analyze the effect of slip boundary conditions on the dynamics of fluids in porous
media by studying the flow of a Newtonian and non-Newtonian Maxwellian fluid in an axisymmetric cylindrical tube (pore), in
which the flow is induced by traveling transversal waves on the tube wall. Like in peristaltic pumping, the traveling transversal
waves induce a net flow of the liquid inside the pore. The viscosity as well as the compressibility of the liquid is taken
into account. This problem has numerous applications in various branches of science, including stimulation of fluid flow in
porous media under the effect of elastic waves and studies of blood flow dynamics in living creatures. The Navier-Stokes equations
for an axisymmetric cylindrical pore are solved by means of a perturbation analysis, in which the ratio of the wave amplitude
to the radius of the pore is small parameter. In the second order approximation, a net flow induced by the traveling wave
is calculated for various values of the compressibility of the liquid, relaxation time and Knudsen number. The calculations
disclose that the compressibility of the liquid, Knudsen number of slip flow and non-Newtonian effects in presence of peristaltic
transport have a strong influence of the net flow rate. The effects of all parameters of the problem are numerically discussed
and graphically explained. 相似文献
2.
Fareed Shereef A. Ibrahim Makram Hannora Ahmed E. El-Desoky M. M. 《Journal of Materials Science: Materials in Electronics》2022,33(19):15346-15358
Journal of Materials Science: Materials in Electronics - Bismuth and manganese oxides were mixed as source-materials using the mechanochemical technique followed by heat treatment to prepare the... 相似文献
3.
Annealed ZnO thin film at 400 °C for two hours was deposited on a glass substrate by using pulsed laser deposition (PLD). The structural properties of the annealed ZnO thin film were studied by XRD, TEM and SEM. Gas sensing properties for different gases such as H2 and LPG were investigated. Applying XRD the size of the nanocrystals is found to be 10.61 nm. SEM of the thin film consisted of many grains distributed uniformly throughout the surface. An annealed ZnO thin film sensor showed the typical n-type semiconducting behavior in the case of H2 and LGP gases at low and high operating temperature range, respectively. When working at 50 and 140 °C the sensor exhibits very good dynamic response–recovery characteristics to H2 and LGP, respectively. These results along with a simple fabrication process demonstrate that the annealed ZnO thin film at 400 °C for two hours is promising for developing low cost and high performance H2 and LPG sensors. The low cost of the sensor element fabrication, high H2 and LPG sensitivity, fast response and quick recovery make the entire fabrication process a front-runner and cost-effective for the production of annealed ZnO thin film H2 and LPG sensors. 相似文献
4.
M. M. El-Desoky M. A. Ali G. Afifi H. Imam 《Journal of Materials Science: Materials in Electronics》2014,25(11):5071-5077
Annealed ZnO thin film at 300, 350, 400, 450 and 500 °C in air were deposited on glass substrate by using pulsed laser deposition. The effects of annealing temperature on the structural and optical properties of annealed ZnO thin films by grazing incident X-ray diffraction (GIXRD), transmittance spectra, and photoluminescence (PL) were investigated. The GIXRD reveal the presence of hexagonal wurtzite structure of ZnO with preferred orientation (002). The particle size is calculated using Debye–Scherrer equation and the average grain size were found to be in the range 5.22–10.61 ± 0.01 nm. The transmittance spectra demonstrate highly transparent nature of the films in visible region (>70 %). The calculation of optical band gap energy is found to be in the range 2.95–3.32 ± 0.01 eV. The PL spectra shows that the amorphous film gives a UV emission only and the annealed films produce UV, violet, blue and green emissions this indicates that the point defects increased as the amorphous film was annealed. 相似文献
5.
M. M. El-Desoky A. M. Al-Syadi M. S. Al-Assiri Hassan M. A. Hassan 《Journal of Materials Science: Materials in Electronics》2018,29(2):968-977
The glasses defined by the formula 37.5Li2O–25V2O5–37.5P2O5 mol% containing different sulfur (0, 10, 50 and 100 mol%) content were studied before and after nanocrystallization. X-ray diffraction and transmission electron micrograph of the heat treated samples indicated nanocrystals embedded in the glass matrix. The average crystallite size was found between 18 and 37 nm. Sulfur (S) behaved as a reducing agent for redox reaction during preparation of glass and affected the conductivity, i.e., the V4+–V5+ or V3+–V4+ion pairs increased with increasing S content and led to increasing conductivity of glasses. After creation of the nanocrystalline phase, S-free glass–ceramic nanocomposite exhibited improvement in electrical conductivity around three orders of magnitude than initial glass. This great improvement of electrical conductivity is related to increase in a concentration of V4+–V5+or V3+–V4+ ion pairs and also, forming of defective and well-conducting regions along the crystallite/glass interfaces. The decrease in electrical conductivity in the 50S glass–ceramic nanocomposite, which possessed the highest crystallite size, could be related to the increase of grain boundaries scattering because of the increasing crystallite size. The conduction was attributed to non-adiabatic small polaron hopping and mostly determined by hopping carrier mobility. 相似文献
6.
Magdy M. Fadel Sally M. El-Ghamrawy Amr M. T. Ali-Eldin Mohammed K. Hassan Ali I. El-Desoky 《计算机、材料和连续体(英文)》2022,73(2):2293-2312
Distributed denial-of-service (DDoS) attacks are designed to interrupt network services such as email servers and webpages in traditional computer networks. Furthermore, the enormous number of connected devices makes it difficult to operate such a network effectively. Software defined networks (SDN) are networks that are managed through a centralized control system, according to researchers. This controller is the brain of any SDN, composing the forwarding table of all data plane network switches. Despite the advantages of SDN controllers, DDoS attacks are easier to perpetrate than on traditional networks. Because the controller is a single point of failure, if it fails, the entire network will fail. This paper offers a Hybrid Deep Learning Intrusion Detection and Prevention (HDLIDP) framework, which blends signature-based and deep learning neural networks to detect and prevent intrusions. This framework improves detection accuracy while addressing all of the aforementioned problems. To validate the framework, experiments are done on both traditional and SDN datasets; the findings demonstrate a significant improvement in classification accuracy. 相似文献
7.
A. Al-Shahrani M. M. El-Desoky 《Journal of Materials Science: Materials in Electronics》2006,17(1):43-49
The electrical properties of xFe2O3−(100 −x) Na2P2O5 glasses with x = 0, 6, 12, 18 and 24 mol% have been studied in the temperature range from 323 to 573 K. The dc conductivity was found to
decrease as the iron content increases while the activation energy increases with increasing iron content in the glasses.
In the high—temperature regime above θD/2 (θD is the Debye temperature), the Mott model of small polaron hopping (SPH) between nearest neighbors is consistent with the
conductivity data. The electron—phonon interaction coefficient γP was very large (66.74–97.60). The electrical conduction of the glasses was confirmed to be non-adiabatic small polaron hopping.
The physical parameters obtained by fitting the experimental results to these models are consistent with glass compositions. 相似文献
8.
M. S. Al-Assiri M. M. El-Desoky 《Journal of Materials Science: Materials in Electronics》2014,25(9):3703-3711
Selected glasses of Fe2O3–PbO2–TeO2 system have been transformed into nanomaterials by annealing at a temperature close to the crystallization temperature (Tc). The effects of the annealing of the present samples on the structural and electrical properties were studied by transmission electron micrograph (TEM), X-ray diffraction (XRD), differential scanning calorimeter, density (d) and dc conductivity (σ). TEM and XRD of glass–ceramic naocrystals indicated nanocrystals embedded in the glassy matrix with average particle size of 20–35 nm. The glass–ceramic naocrystals obtained by annealing at Tc exhibit improvement of electrical conductivity up to four orders of magnitude than the starting glasses. This considerable improvement of electrical conductivity after nanocrystallization is attributed to formation of extensive and dense network of electronic conduction paths which are situated between Fe2O3 nanocrystals and on their surface. The conduction is attributed to non-adiabatic hopping of small polaron. 相似文献
9.
O. A. AL-Hartomy A. A. Al-Ghamdi F. EL-Tantawy M. M. El-Desoky 《Journal of Materials Science》2013,48(8):3067-3074
A new glass–ceramic nanocomposites material was prepared by a thermal nanocrystallization of V2O5–Bi2O3–P2O5 system with different V2O5 content. The amorphous state of glassy materials is confirmed by X-ray diffraction. It was shown by XRD and SEM studies that by suitable heat-treatment glasses can be turned into glass–ceramic nanocomposites consisting of crystallites smaller than 80 nm inserted in the glassy matrix. Also, it was shown that thermal nanocrystallization of as-prepared glassy samples leads to creation of nanocrystalline grains of V2O5, Bi2O3, and BiVO4 phases. The glass–ceramic nanocomposites obtained show giant enhancement of electrical conductivity than the as-prepared glasses. The conductivity enhancement was recognized to interfacial regions adjacent crystalline grains. The conduction of the present glasses and their glass–ceramic nanocomposites was confirmed to be due to primarily non-adiabatic hopping of small polaron between vanadium ions. 相似文献
10.
M. S. Al-Assiri M. M. El-Desoky 《Journal of Materials Science: Materials in Electronics》2013,24(2):784-792
Grain-size effects on the structural and electrical properties as well as ferroelectric behaviour of 10BaTiO3–70V2O5–20Bi2O3 glass–ceramic nano-composite have been studied by scanning electron micrographs (SEM), X-ray diffraction (XRD), differential scanning calorimeter (DSC), dc conductivity (σ) and dielectric (ε) measurements over a wide temperature range. The present glass has been transformed into glass–ceramic nano-composite by annealing at temperatures close to crystallization temperature (Tcr). The XRD and SEM observations have shown that by heat treating at Tcr, the sample under study undergoes structural changes: from amorphous to partly crystalline for 1 and 8 h and to colossal crystallization for 24 h. After heat treated at Tcr for 1 and 8 h, the samples under load consist of small nano-crystallites (average size ca. 20–50 nm) embedded in glassy matrix. However, when the glass heat treated at Tcr for 24 h, the microstructure of the sample changes considerably. It is found that the glass–ceramic nano-composite obtained by heat treated at Tcr for 1 and 8 h exhibit giant improvement of electrical conductivity that is up to four order of magnitude. The electrical conductivity increases with increasing grain-size. The major role in the conductivity enhancement of this glass–ceramic nano-composite is played by the developed interfacial regions “conduction tissue” between crystalline and amorphous phases, in which the concentration of V4+–V5+ pairs responsible for electron hopping, is higher than inside the glassy matrix. The heat treated at Tcr for 24 h leads to decrease of the electronic conductivity. This phenomena lead to disappearance of most “conduction tissue” for electrons and substantial reduction of electronic conductivity. The experimental results were discussed in terms of a model proposed in this contribution which is based on a “core–shell” concept. The glass heat-treated at different times (1, 8 and 24 h) exhibited broad dielectric anomalies in the vicinity of the ferroelectric-to-paraelectric transition temperature. The Curie temperature (Tc), corresponding to ferroelectric phase transition increases with increasing grain-size. The observation of the glass–ceramic nano-composite being studied here can be used to control BaTiO3 grain-size and hence transition temperature by proper adjustment of annealing times. 相似文献