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Journal of Iron and Steel Research International 2015年第7期22卷 582-589页

作者： Ahmed ramadan A.Y.SHASH I.S.EL-MAHALLAWI D.SENK Taha MATTAR Quality Department Faculty of Engineering Cairo University Institute of Ferrous Metallurgy RWTH-Aachen University Central Metallurgical Research and Development Institute

The effect of tramp elements in the steel was intensively studied. It was found that the solubility of tramp elements decreased as the temperature decreased under normal cooling conditions. The tramp elements （Cu, Pb, and Sn） diffused toward the grain boundaries, and intermetallic compounds or rich phases which have low melting points were formed, causing reduction in ductility and failure during the bending test. Rebars with Cu content which were left to air cooling after the last step showed drop in elongation, up to 32 %. On contrast, the samples with high per- centage of tramp elements （Cu, Pb, and Sn） in the billet, which were rolled and subjected to Tempcore process, did not show drop in elongation or failure in bending test （especially for rebar with diameter less than 32 mm）; however, copper must be less than 0.35 mass% to prevent the precipitation of Cu-rich zones of critical size in 32 mm. When quench- ing was applied, the tramp elements remained in the interstitial supersaturated solid solution positions inside the grains and would not have the chance to diffuse and form precipitates, hindering the copper precipitates from reac- hing the critical size necessary for impairing the properties. This would hinder the occurrence of the harmful effect of the tramp elements on the elongation or the hot shortness after rolling.

关键词： recycled steel hot shortness crack susceptibility Tempcore process tramp element residual melt

Solar thermochemical reactionsⅢ:A convenient one-pot synthesis of 1,2,4,5-tetrasubstituted imidazoles catalyzed by high surface area SiO_2 and induced by solar thermal energy

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Chinese Chemical Letters 2009年第7期20卷 812-814页

作者： ramadan A.Mekheimer Afaf M.Abdel Hameed Seham A.A.Mansour Kamal Usef Sadek Chemistry Department Faculty of ScienceEl-Minia UniversityEl-Minia 61519 Egypt Chemistry Department Faculty ofScienceEl-Minia UniversityEl-Minia 61519 Egypt

A simple, convenient and efficient method for the synthesis of 1,2,4,5-tetrasubstituted imidazole derivatives using benzoin, an aromatic aldehyde, an aromatic amine in the presence of ammonium acetate catalyzed by high surface area SiO2 and induced by free solar thermal energy was reported. C 2009 Kamal User Sadek. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

关键词： One-pot synthesis SiO2 Solar thermal energy Tetrasubstituted imidazole

Effect of cold deformation and heat treatment on microstructure and mechanical properties of TC21 Ti alloy

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Transactions of Nonferrous Metals Society of China 2020年第5期30卷 1290-1299页

作者： ramadan N.ELSHAER Khaled M.IBRAHIM Mechanical Engineering Department Tabbin Institute for Metallurgical Studies(TIMS)11918CairoEgypt Casting Technology Department Central Metallurgical R&D Institute(CMRDI)11918CairoEgypt

In the present research work on TC21 titanium alloy(6.5 Al-3 Mo-1.9 Nb-2.2 Sn-2.2 Zr-1.5 Cr), the effects of cold deformation, solution treatment with different cooling rates and then aging on microstructure, hardness and wear property were investigated. A cold deformation at room temperature with 15% reduction in height was applied on annealed samples. The samples were solution-treated at 920 ℃ for 15 min followed by different cooling rates of water quenching(WQ), air cooling(AC) and furnace cooling(FC) to room temperature. Finally, the samples were aged at 590 ℃ for 4 h. Secondary α-platelets precipitated in residual β-phase in the case of solution-treated samples with AC condition and aged ones. The maximum hardness of HV 470 was obtained for WQ + aging condition due to the presence of high amount of residual β-matrix(69%), while the minimum hardness of HV 328 was reported for FC condition. Aging process after solution treatment can considerably enhance the wear property and this enhancement can reach up to about 122% by applying aging after WQ compared with the annealed samples.

关键词： TC21 titanium alloy deformation heat treatment cooling rate microstructure mechanical properties wear

The gravity impact in a rotating micropolar thermoelastic medium with microtemperatures

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Journal of Ocean Engineering and Science 2018年第4期3卷 325-333页

作者： Mohamed I.M.Hilal ramadan S.Tantawi Mohamed I.A.Othman Department of Mathematics Faculty of ScienceP.O.Box 44519Zagazig UniversityZagazigEgypt Department of Basic Science Faculty of EngineeringSinai UniversityAl-ArishEgypt

A model of micropolar thermoelastic medium with microtemperatures influenced by the gravitational field is *** medium rotates with a uniform angular *** physical quantities are obtained analytically and represented gr... 详细信息

关键词： Gravity Micropolar thermoelasticity Microtemperatures Rotation

Analysis of strong refractive effect within 11Li projectile structure

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Chinese Physics C 2021年第2期45卷 414-425页

作者： Kassem O.Behairy M.El-Azab Farid Awad A.Ibraheem Ola ramadan M.Anwar Physics Department Aswan UniversityAswan 81528Egypt Physics Department Assiut UniversityAssiut 71516Egypt Physics Department King Khalid UniversityAbhaSaudi Arabia Physics Department Al-Azhar UniversityAssiut 71524Egypt

In the context of the double folding optical model,the strong refractive effect for elastic scattering of 11Li+12C and 11Li+28Si systems at incident energies of 29,50,and 60 MeV/n is *** folded potentials are generated based on a variety of nucleon-nucleon interactions with the suggested density distributions for the halo structure of 11Li *** rearrangement term(RT)of the extended realistic density dependent CDM3Y6 effective interaction is *** imaginary potential was taken in the traditional standard Woods-Saxon *** results for the calculated potentials are obtained,with a slight effect of the RT in CDM3Y6 *** reproduction with a normalization factor close to one for the observed angular distributions of the elastic scattering differential cross section has been achieved using the derived *** obtained reaction cross-section is studied as a guide by extrapolating our calculations and previous results.

关键词： optical model elastic and inelastic scattering halo nuclei folding model refraction effect

Measurements of natural radionuclides in soil samples from Upper Egypt

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Nuclear Science and Techniques 2008年第5期19卷 302-307页

作者： Shaban ramadan Mohamed HARB Khaled SALAHEL DIN Abd Elbaset ABBADY Mohamed Abd Elleh ALI Rolf MICHEL Physics Department Faculty of ScienceSouth Valley University Center for Radiation Protection and Radioecology Hanover University (ZSR)

This paper presents the results of natural radioactivity measured for the soil of Qena using gamma-ray spectrometry at ZSR,Hanover University,*** samples of radioactive concentrations of ^(238)U-series (^(234)Th, ^(214)pb,and^(214)Bi),^(232)Th-series (^(228)Ac,^(212)pb,and ^(208)T1) and ^(40)K were *** objectives were set:(1) activity levels by surface soil sampling at 0～30 cm depth,(2) dose rates of gamma radiation,radium equivalent,index hazard, and effective dose,and (3) ambient dose rates.

关键词：土壤环境放射能 γ光谱测定法辐射暴露环境剂量

Generalized Truncated Fréchet Generated Family Distributions and Their Applications

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Computer Modeling in Engineering & Sciences 2021年第2期126卷 791-819页

作者： ramadan A.ZeinEldin Christophe Chesneau Farrukh Jamal Mohammed Elgarhy Abdullah M.Almarashi Sanaa Al-Marzouki Deanship of Scientific Research King AbdulAziz UniversityJeddah21589Saudi Arabia Faculty of Graduate Studies for Statistical Research Cairo UniversityAl OrmanGiza Governorate12613Egypt Universite de Caen LMNOCampus IIScience 3Caen14032France Department of Statistics The Islamia University of BahawalpurPunjab63100Pakistan The Higher Institute of Commercial Sciences Al Mahalla Al KubraAlgarbia31951Egypt Statistics Department Faculty of ScienceKing AbdulAziz UniversityJeddah21551Saudi Arabia

Understanding a phenomenon from observed data requires contextual and efficient statistical *** models are based on probability distributions having sufficiently flexible statistical properties to adapt to a maximum of *** examples include the distributions of the truncated Fréchet generated *** this paper,we go even further by introducing a more general family,based on a truncated version of the generalized Fréchet *** generalization involves a new shape parameter modulating to the extreme some central and dispersion parameters,as well as the skewness and weight of the *** also investigate the main functions of the new family,stress-strength parameter,diverse functional series expansions,incomplete moments,various entropy measures,theoretical and practical parameters estimation,bivariate extensions through the use of copulas,and the estimation of the model *** considering a special member of the family having the Weibull distribution as the parent,we fit two data sets of interest,one about waiting times and the other about *** statistical criteria attest that the proposed model is superior over other extended Weibull models,including the one derived to the former truncated Fréchet generated family.

关键词： Truncated distribution general family of distributions incomplete moments entropy copula data analysis

Flat Panel Solar Thermoelectric System Size Optimisation at Different Vacuum Levels

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Open Journal of Energy Efficiency 2015年第4期4卷 53-60页

作者： Kazuz ramadan College of Engineering Technology Tripoli Libya

A systematic experimental investigation to understand the effect of heat loss and the thermoelectric aspect ratio (cross sectional area and length) on a flat plate solar thermoelectric system performance was carried out. The investigation involved a series of experiments on systems with 4 different sizes of thermoelectric generators, and it was tested in 5 different vacuum levels during the steady-state. The detailed experimental investigation provided a substantial amount of data, which revealed that the system performance of both heat and electricity power were improved when the heat lost was minimised. The system’s performance strongly depended on the aspect ratio of the thermoelectric generators. This finding might have a significant impact on the cost of the system by saving the user’s and the manufacturer’s time in examining different TEGs with different aspect ratios in order to get the optimum size optimisation of the hybrid system, as well as reduce the manufacturing cost.

关键词： Flat Roof Top Solar Collector Hybrid Solar Thermoelectric System The Optimal Heat and Electric Power Seebeck Effect Aspect Ratio Vacuum Levels

The vitreomacular interface in different types of agerelated macular degeneration

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International Journal of Ophthalmology(English edition) 2017年第2期10卷 246-253页

作者： Mohamed Abd ElM onaem El-Hifnawy Hisham Ali Ibrahim Amir ramadan Gomaa Mohamed A Elmasry Ophthalmology Department Alexandria University Faculty of MedicineKhartoum SquareAzaritaAlexandria 21526Egypt

AIM： To evaluate the vitreomacular interface in cases with wet age-related macular degeneration（AMD） and to compare them to eyes with dry AMD and normal ***： This was a cross-sectional comparative study that included 87 eyes with wet AMD,42 eyes with dry AMD and 40 eyes without AMD as a control *** coherence tomography（OCT） examination was performed for all patients to assess the vitreomacular ***： In the wet AMD group,34.5% of cases had vitreomacular adhesion（VMA）.Only 14.3% of dry AMD cases and 10% of control cases had *** was a significant difference between the control group and the wet AMD group（P=0.004） as well as the dry and wet AMD group（P=0.017）.There was also a significant difference between the incidence of VMA in patients with subretinal choroidal neovascularization（CNV,type 1） and intraretinal CNV（type 2 or type 3）（P=0.020）.CONCLUSION： There is an association between posterior vitreous attachment and *** is also an increased incidence of VMA with intra-retinal CNV.

关键词： age-related macular degeneration vitreomacular interface optical coherence tomography macula

Microstructural Evolution of Cast Hyper-Eutectic Al-18% Si Alloy during Cyclic Semi-Solid Heat Treatment

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Journal of Minerals and Materials Characterization and Engineering 2015年第5期3卷 390-398页

作者： Mohamed ramadan College of Engineering University of Hail Hail Saudi Arabia Casting Technology Lab. Central Metallurgical Research and Development Institute (CMRDI) Cairo Egypt

The cyclic semi-solid heat treatment represents a promising technique for improving microstructure and mechanical properties of a wide range of metallic alloys. In the current research the influence of cyclic semi-solid heat treatment on microstructure of Al-18% Si alloy containing 0.8% Fe has been studied. All specimens were heated in an electrically heated resistance furnace with heating rate of 10°C·min-1 to 585°C. For a complete one cycle heat treatment (5 min heating time), samples after 5 min holding at 585°C were cooled to a temperature of 550°C in still air cooling and the samples were taken out immediately for water quenching. It was found that heat treatment cycles should be limited to 3 cycles or less in order to maintain fine grain size and globular structure without agglomeration and coalescence. Cyclic semi-solid heat treatment changes morphology of iron-rich intermetallics phases to be plate-like and fine plate iron-rich intermetallics phases, in stead of needle-like iron-rich intermetallics phases that are observed in as-cast samples. Cyclic heating shows a relatively higher hardness for all heating cycles compared with as-cast one due to its finer and globular structure. Cyclic semi-solid heat treatment technique results in lower coarsening rate constant compared with isothermal heat treatment one due to coarsening discontinuous effect.

关键词： Microstructural Cyclic Semi-Solid Heat Treatment Al-18% Si Microstructure Hyper-Eutectic Cast