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Corrosion Behaviours of Copper Alloy in Solutions Containing Na_2SO_4 and NaCl with Different Concentrations

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Journal of Materials Science & Technology 2002年第6期18卷 549-551页

作者： a.a.el-meligi Chem. Dept. Durham Univ. DH1 3LE South Road Durham United Kingdom

Potentiodynamic polarisation, potential-time measurements, X-ray diffraction (XRD) and infrared spectroscopy (IR) have been used to investigate the effect of different concentrations of Na2SO4 in the absence and presence of NaCI, on the corrosion of Cu-alloy. The electrochemical measurements showed that the increase of Na2SO4 concentration led to increase the corrosion current density of Cu alloy and vice versa. The presence of NaCI shifted the potential to more cathodic potential, which had a great influence on the protectiveness of the Cu oxide layer formed on the surface in presence of Na2SO4. The spectrometric measurements indicated the constituents of the film formed on the alloy surface were mainly Cu2O, in addition to the oxides, NiO and Fe2O3, which were traced by XRD analysis.

关键词： Cu-alloy Polarisation X-ray diffraction Na2SO4 NaCl Oxide film

Intercalation and Stability of Layered Semiconductive Material in Corrosive Environment

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Journal of Materials Science & Technology 2006年第2期22卷 252-256页

作者： a.a.el-meligi electrochem.and Corrosion Lab. Physical Chemistry Dept. National Research CentreDokkiCairoEgypt

The intercalation of 4-methyl pyridine （4-picoline） into layered semiconductive material （MnPS3） and the stability of the resulting materials in corrosive environments （water, HCI and open atmosphere） were investigated. Powder X-ray diffraction （XRD） indicated that the presence of water and hydrochloric acid greatly influenced the existing form of intercalation and its orientation in the interlayer of the host. Atmospheric environment （open air） affected the guest orientation in the interlayer of the host material. Phase transformation occurred and the material was stable. The intercalated compounds could be indexed in the trigonal unit cell. The XRD patterns exhibited sharp hkl reflections of the intercalated compounds, which formed in water and HCI, confirming that the materials were well crystalline and stable in corrosive environments.

关键词： MnPS3 Intercalation Stability XRD Corrosive environments

Corrosion Penetration and Crystal Structure of AA5022 in HCl Solution and Rare Earth elements

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Journal of Materials Science & Technology 2005年第3期21卷 324-330页

作者： a.a.el-meligi S.H.Sanad A.A.Ismail A.M.Barakat electrochem. and Corrosion Lab. Physical Chemistry Dept. National Research Centre Dokki Cairo EgypElectrochem. and Corrosion Lab. Physical Chemistry Dept. National Research Centre Dokki Cairo EgypElectrochem. and Corrosion Lab. Physical Chemistry Dept. National Research Centre Dokki Cairo EgypChemistry Dept. Faculty of Science Cairo University Cairo Egypt

Al-alloy (AA5022) corrosion penetration (CP) and crystal structure were investigated after running static immersion corrosion tests in 1 mol/L HCl solution and different concentrations of rare earth elements (La3+), (Ce3+) and their combination, at different temperatures. X-ray diffraction (XRD) was used to examine the surface structure before and after immersion, and secondary electron detector (SED) was operated to study surface morphology. In 1 mol/L HCI solution the corrosion penetration increased with increasing temperature and immersion time. The increase of La3+ concentrations up to 1000×10-6 g/L led to the decrease in the corrosion penetration, and the decrease in Ce3+ concentrations up to 50×10-6 g/L decreases the corrosion penetration of the alloy. Mix3 (combination of La3+ and Ce3+) dramatically reduced the corrosion penetration. This suggests that a synergistic effect exists between La3+ and Ce3+. The reaction kinetics both in absence and presence of La3+ and Ce3+ and their combination would follow a parabolic rate law. The XRD patterns revealed that the intensities of certain hkl phases are affected. The crystalline structure has not been deformed either before or after testing and there are no additional peaks except that of the as-received alloy. In the case of accelerating CP, the surface morphology shows that the roughness and voids of surface are increased.

关键词： Al-alloy Corrosion penetration Crystal structure XRD

Indole and Its Derivatives as Corrosion Inhibitors for C-Steel during Pickling

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Journal of Materials Science & Technology 2000年第3期16卷 291-296页

作者： S.H.Sanad, A.A.Ismail and a.a.el-meligi (Physical Chemistry Dept., National Research Centre, Dokki, Cairo, Egypt) Physical Chemistry Dept. National Research Centre Dokki Cairo Egypt

The corrosion of three types of C-steel in 10% hydrochloric acid solution has been investigated in the absence and the presence of the inhibitors, indole (A), indole acetic acid (B), indole butyric acid (C), and 3-acetyl indole (D), by weight-loss measurements at different temperatures (30～70℃). The results showed that inhibiting efficiency depended upon the presence of the substituted groups in the pyrrole ring. The inhibiting efficiency of the inhibitors increased in the order: Inh. Celucidated the effect of temperatures and molecular structure on the inhibition efficiency. The activation energy, Ea, of the three alloys was calculated and it was found that it depended on the type of steel and inhibitor.

关键词： Carbon steel

Inhibiting Effect of Indole and Some of Its Derivatives on Corrosion of C-Steel in HCl

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Journal of Materials Science & Technology 2000年第4期16卷 397-400页

作者： A.A.Ismail, S.H.Sanad and a.a.el-meligi (Physical Chemistry Dept., National Research Centre, Dokki, Cairo, Egypt) Physical Chemistry Dept. National Research Centre Dokki Cairo Egypt

The Inhibiting effect of indole (A), indole acetic acid (B), indole buteric acid (C), and 3-acetyl indole (D). on the corrosion of three carbon steels in 10% HCl was investigated by using galvanostatic polarization method and open circuit potential measurements. It was observed that the inhibiting action of inhibitors increased with increasing inhibitor concentration. The best inhibiting effect obtained at the highest concentration (200×10^(-6)g/L) of the inhibitors for the three carbon steels. According to polarization and open circuit potential methods the inhibitors have effect on both anodic and cathodic area.

关键词： Nitrogen compounds

Stability analysis of a time-delayed Van der Pol–Helmholtz–Duffing oscillator in fractal space with a non-perturbative approach

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Communications in Theoretical Physics 2024年第4期76卷 22-31页

作者： Yusry O el-Dib Department of Mathematics Faculty of EducationAin Shams UniversityRoxyCairoEgypt

The time-delayed fractal Van der Pol–Helmholtz–Duffing(VPHD)oscillator is the subject of this paper,which explores its mechanisms and highlights its stability *** time-delayed technologies are currently garnering significant attention,the focus of this research remains crucially relevant.A non-perturbative approach is employed to refine and set the stage for the system under *** innovative methodologies introduced yield an equivalent linear differential equation,mirroring the inherent nonlinearities of the ***,the incorporation of quadratic nonlinearity into the frequency formula represents a cutting-edge *** analytical solution's validity is corroborated using a numerical *** conditions are ascertained through the residual Galerkin ***,it is observed that the delay parameter,in the context of the fractal system,reverses its stabilizing influence,impacting both the amplitude of delayed velocity and the *** analytical solution's precision is underscored by its close alignment with numerical ***,the study reveals that fractal characteristics emulate damping *** its applicability across diverse nonlinear dynamical systems,this non-perturbative approach emerges as a promising avenue for future research.

关键词： Van der Pol-Helmholtz-Duffing oscillator fractal space time-delay non-perturbative approach stability analysis el-Dib's frequency formula

Comparison between seismic analysis of twisting and regular 52-story towers considering soil-structure interaction

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Earthquake Engineering and Engineering Vibration 2024年第3期23卷 663-675页

作者： Mohamed Naguib Abouelsaad Mohammed Shaaban Salah el Bagalaty Mohamed E.el Madawy Structural Engineering Department Faculty of EngineeringMansura UniversityMansoura 35511Egypt Faculty of Engineering Delta University for Science and TechnologyGamasa 35712Egypt

A dynamic analysis of both twisting and regular towers is carried out to determine the results of considering soil-structure interaction(SSI)on high-rise *** addition,the difference between the seismic performance of using twisting towers over regular ones is *** twisting tower is a simulation of the Evolution Tower(Moscow).The towers’skeletons consist of RC elements and rest on a reinforced concrete piled-raft *** soil model is considered as multi-layered with the same soil properties as the zone chosen for the analysis(New Mansoura City,Egypt).The only difference between both towers is their shape in *** whole system is modelled and analyzed in a single step as one full 3D model,which is known as the direct approach in *** analyses are carried out using finite-element software(Midas GTS NX).Dynamic output responses due to three records of seismic loads are proposed and presented in some *** on the results,it is concluded that SSI has a considerable effect on the dynamic response of tall buildings mainly because of the foundation flexibility,as it leads to lengthening the vibration period,increasing the story drift and the base shear for both cases.

关键词： soil-structure interaction seismic analysis twisting towers base shear story drift finite element method Midas GTS NX

Gender-Based Analysis of User Reactions to Facebook Posts

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Big Data Mining and Analytics 2024年第1期7卷 75-86页

作者： Yassine el Moudene Jaafar Idrais Rida el Abassi Abderrahim Sabour Mathematical Engineering and Computer Science Laboratory Faculty of SciencesIbn Zohr UniversityAgadir 8706Morocco Department of Computer Science Mathematical−High School of Technology Ibn Zohr UniversityAgadir 8706Morocco

Online Social Networks(OSNs)are based on the sharing of different types of information and on various interactions(comments,reactions,and sharing).One of these important actions is the emotional reaction to the *** diversity of reaction types available on Facebook(namely FB)enables users to express their feelings,and its traceability creates and enriches the users’emotional identity in the virtual *** paper is based on the analysis of 119875012 FB reactions(Like,Love,Haha,Wow,Sad,Angry,Thankful,and Pride)made at multiple levels(publications,comments,and sub-comments)to study and classify the users’emotional behavior,visualize the distribution of different types of reactions,and analyze the gender impact on emotion *** of these can be achieved by addressing these research questions:who reacts the most?Which emotion is the most expressed?

关键词： profiling knowledge extraction data mining emotion mining social media data crawling Facebook reactions gender

Existence results and behavior analysis for nonlinear age-dependent population dynamics problems with conformable fractional operator

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International Journal of Biomathematics 2024年第5期17卷 229-256页

作者： Hiba el Asraoui M'hamed el Omari Ali el Mfadel Khalid Hilal Laboratory of Applied Mathematics Scientific Computing Sultan Moulay Slimane University BP 523 Beni MellalMorocco

In this paper,we investigate the existence of solutions and analyze the large-time behavior for Gurtin-Maccamy population model involving conformable fractional *** a preliminary step,we construct a generic structure of the solution associated with our proposed model by utilizing some basic properties and tools of conformable fractional *** establish the existence of a unique solution of the given model with the given initial *** last,by using the upper and lower solutions for the characteristic equation,we define the upper and lower boundaries for the obtained solution and describe the large-time behavior of the total population.

关键词： Age-dependent population conformable fractional operator upper and lower boundary of the solution dynamics of populations