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Thermomechanical Analysis of (Cu_(0.5)Tl_(0.5))-1223 Substituted by Pr and La

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Journal of Materials Science & Technology 2012年第2期28卷 169-176页

作者： A.i.Abou Aly R.Awad i.h.ibrahim M.Kamal M.Anas Physics Department Faculty of ScienceAlexandria University Physics Department Faculty of ScienceMansoura University

The thermomechanical analysis （TMA） of Cu0.5T10.5Ba2Ca2-xRxCu30110-δ, where R=Pr and La, with 0.0〈x〈0.15, was carried out in temperature range from 450 to 1145 K. The samples were prepared by singlestep solid state reaction technique. The prepared samples were characterized by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The superconductivity of the prepared samples was investigated by electrical resistivity measurement. The results showed that low substitution content enhanced the （Cu0.5Tlo.5）- 1223 phase formation, while the higher substitution content degraded this phase. The higher superconducting transition temperatures Tc were found to be 114 K and 109 K at x= 0.025 for Pr- and La-substitutions, respectively. The average linear thermal expansion coefficient increased as x increased, while the shrinkage temperature decreased as x increased. Those results were emphasized by porosity and Vickers microhardness calculations. Debye temperature 0D was calculated from the linear thermal expansion coefficient data and correlated to Tc to estimate the electron-phonon coupling λep.

关键词： (Cu0.5Tl0.5)-1223 Thermomechanical analysis Thermal expansion coefficient Debye temperature

Electrical and mechanical properties of (Bi, Pb)-2223 substituted by holmium

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Journal of Advanced Ceramics 2016年第1期5卷 54-69页

作者： W.ABDEEN S.MARAhBA R.AWAD A.i.ABOU ALY i.h.ibrahim M.MATAR Superconductivity and Metallic Glass Lab Physics Department Faculty of ScienceAlexandria University Alexandria EgyptPhysics Department University College at Al-Gamom Umm Al-Qura University Saudi Arabia Physics Department Faculty of Science Beirut Arab University(BA U) Beirut Lebanon Superconductivity and Metallic Glass Lab Physics Department Faculty of ScienceAlexandria University Alexandria Egypt

The effect of the partial substitution of Ca2+ by ho3+ ions on the electrical and mechanical properties of the superconducting phase (Bi,Pb)-2223 was studied. Superconducting samples of the type (Bi1.8Pb0.4)Sr2Ca2.1?x ho xCu3.1O10+δ were prepared by solid-state reaction technique under ambient pressure, and characterized by means of X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The superconducting transition temperature T c and pseudogap temperature T* were estimated from electrical resistivity measurements, while the critical current density J c was determined from i-V curves. The electrical resistivity data were discussed according to bipolaron model in the absence of thermally excited individual polarons. The sample with x = 0.025 showed the highest phase volume fraction, T c, and J c. Room temperature Vickers microhardness measurements were carried out at different applied loads (0.25-5 N) in order to investigate the performance of the mechanical properties of (Bi1.8Pb0.4)Sr2Ca2.1?x ho xCu3.1O10+δ phase. it was found that all the samples exhibit normal indentation size effect (iSE). The Vickers microhardness number h V increased as x increased from 0 to 0.025. The experimental results were discussed in view of Meyer’s law, hays-Kendall (hK) approach, elastic/plastic deformation (EPD) model, and proportional specimen resistance (PSR) model. The load independent (true) microhardness of (Bi1.8Pb0.4)Sr2Ca2.1?x ho xCu3.1O10+δ superconducting samples showed identical behavior to that of the PSR model.

关键词： (Bi,Pb)-2223 phase ho substitution Vickers microhardness bipolaron model pesudogap temperature

Arctic sea-ice extent: No record minimum in 2023 or recent years

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Atmospheric and Oceanic Science Letters 2025年第1期18卷 52-55页

作者： Ola M.Johannessen Tor i.Olaussen Nansen Scientific Society BergenNorway Nansen Environmental and Remote Sensing Center BergenNorway

Arctic sea-ice extent reaches its minimum each year in September. On 11 September 2023 the minimum was 4.969 million square kilometers(***^(2)). This was not a record low, which occurred in 2012, when the minimum was 4.175 ***^(2), 0.794 ***^(2) less than the minimum in 2023. however, the ice extent had decreased by 0.432 ***^(2) compared with 2022. Nevertheless, the summer melting in 2023 was remarkably less than expected when considering the strong heat waves in the atmosphere and ocean, with record temperatures set around the world. in general, there is a high correlation between the long-term decrease in sea-ice extent and the increasing CO_(2) in the atmosphere, where the increase of CO_(2) in recent decades explains about 80% of the decrease in sea ice in September, while the remainder is caused by natural variability.

关键词： Sea ice Arctic Minimum ice Climate

Effect of graphene addition on the physicomechanical and tribological properties of Cu nanocomposites

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international Journal of Minerals,Metallurgy and Materials 2022年第1期29卷 161-167页

作者： Adnan i.Khdair A.ibrahim Mechanical Engineering Department Faculty of EngineeringKing Abdulaziz UniversityP.O.Box 80204JeddahSaudi Arabia Jordan University of Science and Technology Mech.Eng.Dep.P.O.Box 3030Irbid 2011Jordan higher Technological institute Tenth of Ramadan CityEgypt

This paper presents an experimental investigation of the mechanical and tribological properties of Cu-graphene nanosheets(GN)*** employed the electroless coating process to coat GNs with Ag particles to avoid its reaction with Cu and the formation of intermetallic *** analyzed the effect of GN content on the structural,mechanical,and tribological properties of the produced *** showed that the electroless coating process is an efficient technique to avoid the reaction between Cu and C and the formation of intermetallic *** addition of GNs significantly improves the mechanical and tribological properties of Cu ***,the addition of GNs needs to be done carefully because,after a certain threshold value,the mechanical and tribological properties are negatively *** optimum GN content is determined to be 0.5vol%,at which hardness,wear rate,and coefficient of friction are im-proved by 13%,81.9%,and 49.8%,respectively,compared with Cu *** improved properties are due to the reduced crys-tallite size,presence of GNs,and homogenous distribution of the composite constituents.

关键词： copper graphene nanosheets coating mechanical properties wear

Comparison of impact Properties for Carbon and Low Alloy Steels

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Journal of Materials Science & Technology 2011年第10期27卷 931-936页

作者： O.h.ibrahim Metallurgy Dept. Nuclear Research CentreAtomic Energy Authority

The impact properties of hot rolled carbon steel （used for the manufacture of reinforcement steel bars） and the quenched ＆ tempered （Q＆T） low alloy steel （used in the pressure vessel industry） were determined. The microstructure of the hot rolled carbon steel contained ferrite/pearlite phases, while that of the quenched and tempered low alloy steel contained bainite structure. impact properties were determined for both steels by instrumented impact testing at temperatures between -150 and 200℃. The impact properties comprised total impact energy, ductile to brittle transition temperature, crack initiation and propagation energy, brittleness transition temperature and cleavage fracture stress. The Q＆T low alloy steel displayed much higher resistance to ductile fracture at high test temperatures, while its resistance to brittle fracture at low test temperatures was a little higher than that of the hot rolled carbon steel. The results were discussed in relation to the difference in the chemical composition and microstructure for the two steels.

关键词： Ferritic/pearlitic steel Bainitic steel impact properties

Structural, M?ssbauer spectroscopy, magnetic properties, and thermal measurements of Y(3-x)Dy_x Fe_5O_(12)

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Chinese Physics B 2018年第10期27卷 558-564页

作者： Mahdi Lataifeh Qassem i Mohaidat Sami h Mahmood ibrahim Bsoul Mufeed Awawdeh ibrahim Abu-Aljarayesh Mu'ath Altheeba Physics Department Yarmouk University Irbid 21163 Jordan Physics Department The University of Jordan Amman 11942 Jordan Physics Department AI al-Bayt University Mafraq 13040 Jordan

Yttrium iron garnet powder samples（Y3-xDyxFe5O12）, where part of yttrium ions are substituted by dysprosium ions with different concentrations are prepared by the solid state reaction method. The properties of the prepared samples are examined by different methods such as x-ray diffraction（XRD）, Mssbauer spectroscopy, macroscopic magnetization measurements, and thermal measurements. The XRD measurements show that all the samples reveal the presence of a single garnet phase with a BCC structure. Room temperature Mssbauer spectra indicate that iron ions occupy three magnetic sites, i.e., two octahedral sites and one tetrahedral site. The saturation magnetization and the initial magnetic susceptibility decrease with the increase of Dy^3＋ substitution. The Curie temperature obtained from the thermal measurements seems to be independent of Dy^3＋ substitution.

关键词： Mossbauer spectroscopy magnetic properties x-ray diffraction differential scanning calorimetry

Structural and Magnetic Studies of Ga-doped Yttrium iron Garnet

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Journal of Wuhan University of Technology(Materials Science) 2021年第1期36卷 13-21页

作者： Khozima hamasha Qassem i Mohaidat Mahdi Lataifeh ibrahim Bsoul Sami h Mahmood Department of Basic Sciences Al-Huson University CollegeAl-Balqa Applied UniversityAl-SaltJordan Physics Department Yarmouk UniversityIrbid 21163Jordan Physics Department Al al-Bayt UniversityMafraq 13040Jordan Physics Department The University of JordanAmman 11942Jordan

Ga-doped Yttrium iron Garnet (Y_(3)Ga_(x)Fe_(5-x)O_(12),Ga:YiG) was prepared by solid state reaction method and sintering at 1 300 ℃.Rietveld analysis of X-ray diffraction patterns indicated that all samples crystallized in a single cubic structure (space group ia-3d) with decreasing lattice constant as Ga concentration *** surface micrograph images of YiG samples showed highly compacted grains with small reduction in the grain size with increasing Ga *** spectroscopy measurements confirmed the replacement of Fe^(3+) ions by Ga^(3+) ions in the garnet structure was revealed by the observed blue shifts in Raman *** saturation magnetization decreased from 28.2 to 4.98 emu g^(-1) with increasing x from 0.0 to 1.0 due to the preferential substitution of Ga^(3+) ions for Fe^(3+) ions at tetrahedral *** temperature Mössbauer spectra for the samples revealed a reduction of the hyperfine field values for octahedral and tetrahedral sites,and the development of additional components with increasing Ga *** of the magnetic data and Mössbauer spectra confirmed that spin canting in the substituted garnets plays an important role in explaining the observed reduction of the saturation magnetization as x increased.

关键词： rare earth iron garnet structural characteristics scanning electron microscope raman spectroscopy magnetic properties mössbauer spectroscopy

Generalized thermoelasticity of the thermal shock problem in an isotropic hollow cylinder and temperature dependent elastic moduli

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Chinese Physics B 2012年第1期21卷 289-294页

作者： ibrahim A.Abbas Mohamed i.A.Othman Department of Mathematics Faculty of Science and Arts-KhulaisKing AbdulAziz UniversityJeddahSaudi Arabia Department of Mathematics Faculty of ScienceSohag UniversitySohagEgypt Department of Mathematics Faculty of ScienceZagazig UniversityP.O.Box 44519ZagazigEgypt

in this paper, we construct the equations of generalized thermoelasicity for a non-homogeneous isotropic hollow cylider with a variable modulus of elasticity and thermal conductivity based on the Lord and Shulman theory. The problem has been solved numerically using the finite element method. Numerical results for the displacement, the temperature, the radial stress, and the hoop stress distributions are illustrated graphically. Comparisons are made between the results predicted by the coupled theory and by the theory of generalized thermoelasticity with one relaxation time in the cases of temperature dependent and independent modulus of elasticity.

关键词： generalized thermoelsticity thermal shock temperature dependent elastic moduli finiteelement method

improving the reconstruction efficiency of sparsity adaptive matching pursuit based on the Wilkinson matrix

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Frontiers of information Technology & Electronic Engineering 2018年第4期19卷 503-512页

作者： Rasha ShOiTAN Zaki NOSSAiR i.i.ibrahim Ahmed TOBAL Computer and Systems Department Electronic Research Institute Electronics Communicationsand Computer DepartmentHelwan University

Sparsity adaptive matching pursuit(SAMP)is a greedy reconstruction algorithm for compressive sensing *** reconstructs signals without prior information of sparsity and presents better reconstruction performance for noisy signals compared to other greedy ***,SAMP still suffers from relatively poor reconstruction quality especially at high compression *** the proposed research,the Wilkinson matrix is used as a sensing matrix to improve the reconstruction quality and to increase the compression ratio of the SAMP ***,the idea of block compressive sensing(BCS)is combined with the SAMP technique to improve the performance of the SAMP *** simulations have been conducted to evaluate the proposed BCS-SAMP technique and to compare its results with those of several compressed sensing *** results show that the proposed BCS-SAMP technique improves the reconstruction quality by up to six decibels(d B)relative to the conventional SAMP *** addition,the reconstruction quality of the proposed BCS-SAMP is highly comparable to that of iterative ***,the computation time of the proposed BCS-SAMP is less than that of the iterative techniques,especially at lower measurement fractions.

关键词： Block compressive sensing Sparsity adaptive matching pursuit Greedy algorithm Wilkinson matrix