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Effect of alumina content and heat treatment on microstructure and upconversion emission of Er^(3+)ions in oxyfluoride glass-ceramics

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Journal of Rare Earths 2012年第12期30卷 1228-1234页

作者： Mohammad Hasan Imanieh Bijan Eftekhari Yekta Vahak Marghussian Inocencio Rafael Martin Benenzuela Alberto Hernandez Creus Saeed Shakhesi esmaeil eslami Department of Materials Ceramic DivisionIran University of Science and Technology Nanotechnology Department Engineering Research Institute Department of Física Fundamental Electrónicay SistemasUniversity of La LagunaC.Astrofísico Francisco Sánchezs/n E-38206 La LagunaTenerifeSpain MALTA Consolider Team University of La LagunaC.Astrofísico Francisco Sánchezs/n E-38206 La LagunaTenerifeSpain Department of Química Física Instituto de Materialesy NanotecnologíaUniversity of La Laguna38205-La LagunaTenerifeSpain Nanotechnology Department Engineering Research Institute Tehran Department of Physics Iran University of Science and Technology (IUST)NarmakTehranIran

The effect of alumina content and heat treatment temperature and time, on microstructure and Er3＋（0.5 mol.%） emission of oxyfluoride glass-ceramics were investigated in this research. Two values of 1.8 （SA1.8Er0.5） and 2.18 （SA2.18Er0.5） were selected in this research for SiO2/Al2O3 ratio. According to DTA results, precursor glasses were heat treated at 630, 660 and 690 ℃ for 4 h and some glasses were also heat treated at 630 ℃ for 48 and 72 h. The results indicated that alumina content had significant effect on phase separation and viscosity of the glasses. Therefore the size, size distribution, and volume concentration of nano CaF2 crystals which precipitated during the heat treatment depended on alumina content of the glass. Due to the much smaller size of the precipitated CaF2 crystals in the glasses of low alumina content, these samples maintained excellent transparency and had narrower crystal size distribution than the high alumina glasses. The crystal size was increased markedly with the temperature increasing from 630 to 690 ℃. On the other hand a slight increase was observed in the crystal size by raising the heat treatment time in both glasses. Results indicated that in low alumina content glass （SA2.18Er0.5） the size of CaF2 nanocrystals was controlled in one order of magnitude. The increase of heat treatment time and temperature led to the incorporation of Er3＋ ions into CaF2 crystalline phase, increasing significantly the upconversion intensity. After heat treatment at 690 ℃for 4 h, atomic force microscope （AFM） revealed the development of small crystals with an average size of 80 and 30 nm in SA1.8Er0.5 and SA2.18Er0.5 samples, respectively.

关键词： oxyfluorides glass-ceramic CaF2 nanocrystals SiO3/Al2O3 ratio rare earths

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Development of a new correlation to calculate permeability for flows with high Knudsen number

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Chinese Physics B 2016年第2期25卷 271-277页

作者： esmaeil Dehdashti Department of Mechanical Engineering University of Tehran

Flows with high Knudsen number play a prominent role in many engineering applications. The present study is an effort toward the simulation of flow with high Knudsen number using modified lattice Boltzmann method （LBM） through a porous medium in a channel. The effect of collision between molecules and solid walls, which is required to accurately simulate transition flow regime, is taken into account using a modified relaxation time. Slip velocity on the wall, which is another significant difficulty in simulating transition flow regime, is captured using the slip reflection boundary condition （SRBC）. The geometry of porous medium is considered as in-line and staggered. The results are in good agreement with previous works. A new correlation is obtained between permeability, Knudsen number and porosity for flows in transition flow regimes.

关键词： flow in porous micro-channel lattice Boltzmann method high Knudsen number permeability

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Corrosion Behaviors of Two Types of Commercial Stainless Steel after Plastic Deformation

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Journal of Materials Science & Technology 2010年第9期26卷 833-838页

作者： esmaeil Jafari Materials Science and Engineering Department Islamic Azad University Shiraz Branch

The influence of deformation temperature,strain rate and alloying elements such as chromium,nickel,copper,on corrosion resistance of a 304 stainless steel after plastic deformation was *** techniques employed were tensile test at room and elevated temperature,deep drawing tests at various strain rates,X-ray diffraction test and potentiodynamic and cyclic polarization,metallography by optical and scanning electron *** showed that chromium,nickel and copper had a significant effect on corrosion resistance of steel after plastic *** was observed that corrosion resistance after plastic deformation was a function of deformation temperature and alloying elements.

关键词： Corrosion resistance Plastic deformation Stainless steel Phase transformation Polarization test

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Effect of copper slag recovery on hydrometallurgical cut-off grades considering environmental aspects

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Journal of Central South University 2016年第4期23卷 798-807页

作者： AFSHIN AKBARI esmaeil RAHIMI Department of Mining Engineering Islamic Azad University-Central Tehran Branch Department of Mining Engineering Islamic Azad University-South Tehran Branch

Determining the hydrometallurgical cut-off grades specifies the destination of low grade materials and this is subjected to more benefits in mining. Copper production rate is considered as one of the fundamental issues in hydrometallurgical cut-off grades determination. Slags are remarked as one of the main sources of copper. It is not only regarded as a waste but also identified as another resource extracting base metals. Slags are characterized by copper high grade. Thus, slag copper recovery can be led to different cut-off grades and net present value(NPV). The current research scrutinizes the effect of slag recovery by both flotation and hydrometallurgical methods on the hydrometallurgical cut-off grades. For this purpose, the optimum cut-off grade algorithms of hydrometallurgical methods are developed by considering associated environmental parameters, incomes and also the costs. Then, their optimum amounts are calculated with NPV maximization as an objective function. The results indicate that considering slag copper recovery in the hydrometallurgical cut-off grade algorithms reduces the environmental costs caused by slag dumping and leads to more NPV by 9%.

关键词： hydrometallurgy cut-off grades low grade materials waste floatation slag copper recovery environmental parameters slag dumping NPV maximization

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Investigation of sensitivity and threshold voltage shift of commercial MOSFETs in gamma irradiation

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Nuclear Science and Techniques 2016年第6期27卷 166-171页

作者： Saleh Ashrafi Baharak eslami Faculty of Physics University of Tabriz Department of Physics Payame Noor University

This article is about the absorbed-dose-dependent threshold voltage shift of the MOSFET *** of the MOSFETs has been tested in different gate *** of the transistors for 662 ke V gamma ray is studied in 1–5 Gy dose *** was found that for transistors irradiated in biased mode,significant changes in the threshold voltage occurred,and the sensitivity to gamma rays increased with the bias voltage.

关键词：阈值电压漂移 MOSFET γ射线照射敏感性商业吸收剂量偏置电压晶体管

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Three-dimensional heat transfer in a particulate bed in a rotary drum studied via the discrete element method

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Particuology 2020年第4期18卷 155-162页

作者： esmaeil Yazdani Seyed Hassan Hashemabadi Computational Fluid Dynamics(CFD)Research Laboratory School of ChemicalPetroleum and Gas EngineeringIran University of Science and Technology(IUST)16846-13114 TehranIran

We simulated three-dimensional heat transfer inside a horizontal rotating drum using the discrete element method and a thermal conduction *** aim was to determine the effect of end-wall heating on thermal behavior of a granular *** simulation showed that the end-wall heating significantly affects the axial temperature profile of the bed,particularly when the length-to-diameter ratio is *** near the wall heated faster and became more thermally uniform than those in the center of the *** region affected by the end heating gradually increased over *** the rotation speed enhanced the heat conduction rate,and increasing the fill level reduced the mean temperature and thermal uniformity of the granular *** transfer was also simulated for drums with different length-to-diameter ratios.

关键词： Discrete element method Three-dimensional heat transfer Rotary drum Numerical simulation Axial temperature Particulate bed

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Comparison of effective parameters for copper powder production via electrorefining and electrowinning cells and improvement using DOE methods

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International Journal of Minerals,Metallurgy and Materials 2011年第6期18卷 731-740页

作者： Ebrahim Akbarzadeh Sayyed esmaeil Shakib Department of Materials Science and Metallurgical Engineering Shahid Bahonar University of Kerman

The influences of cupric ion concentration （5-35 g/L）,current density （500-2000 A/m2）,circulation rate of the electrolyte solution （15-120 mL/min）,and temperature （25-60℃） on the physical and chemical properties of copper powders obtained in electrolysis cells were *** industrial processes,electrorefining （ER） cells with a synthetic electrolyte and electrowinning （EW） cells with an original solution of coppermineral leaching,were utilized to produce copper ***,the statistical full factorial method of design of experiments （DOE） was employed to investigate the interaction or the main effects of *** results show that increasing the copper concentration and temperature can increase the grain size,apparent density,and electrical energy *** the other hand,increasing the current density and circulation rate of the electrolyte can decrease *** production process is optimized via DOE to control the interactive and main effects to produce copper powders with favorable properties.

关键词： copper powders electrorefining electrowinning grain size apparent density

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3-Bihom-ρ-Lie Algebras, 3-Pre-Bihom-ρ-Lie Algebras

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Chinese Annals of Mathematics,Series B 2023年第2期44卷 193-208页

作者： Zahra BAGHERI esmaeil PEYGHAN Department of Mathematics Faculty of ScienceArak UniversityArak 38156-8-8349Iran

The purpose is to introduce the notions of 3-Bihom-ρ-Lie algebras and 3-preBihom-ρ-Lie *** authors describe their constructions and express the related lemmas and ***,they define the 3-Bihom-ρ-Leibniz algebras and show that a3-Bihom-ρ-Lie algebra is a 3-Bihom-ρ-Leibniz algebra with theρ-Bihom-skew symmetry ***,a combination of a 3-Bihom-ρ-Lie algebra bracket and a Rota-Baxer operator gives a 3-pre-Bihom-ρ-Lie algebra structure.

关键词： 3-Bihom-ρ-Lie algebra 3-Pre-Bihom-ρ-Lie algebra Rota-Baxer operator

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Riemannian Geometry on Hom-ρ-commutative Algebras

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Chinese Annals of Mathematics,Series B 2022年第2期43卷 175-194页

作者： Zahra BAGHERI esmaeil PEYGHAN Department of Mathematics Faculty of ScienceArak UniversityArak38156-8-8349Iran

Recently,some concepts such as Hom-algebras,Hom-Lie algebras,Hom-Lie admissible algebras,Hom-coalgebras are studied and some classical properties of algebras and some geometric objects are extended on *** this paper by recalling the concept of Hom-ρ-commutative algebras,the authurs intend to develop some of the most classical results in Riemannian geometry such as metric,connection,torsion tensor,curvature tensor on it and also they discuss about differential operators and get some results of differential calculus by using *** notions of symplectic structures and Poisson structures are included and an example ofρ-Poisson bracket is given.

关键词： Extended hyper-plan Hom-ρ-commutative algebra ρ-Poisson bracket

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A novel approach towards parametric assessment of reliability and resilience of high voltage mica-based insulation systems by statistical analysis of experimental failure data

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High Voltage 2024年第2期9卷 495-507页

作者： Shahram Negari Davoud esmaeil Moghadam Integrated Power Services ClevelandOhioUSA Valeo eAutomotive Germany GmbH ErlangenGermany

Insulation systems in high-voltage electric machines play a pivotal role in the reliable operation and longevity of the ***-based insulation materials have proven to possess and maintain excellent dielectric properties in the long run and prevent premature insulation *** qualifications tests,such as voltage endurance,are outlined in IEC and IEEE *** authors,however,take a different parametric approach,opting for reliability assessment of insulation systems using derived three-parameter Weibull ***,instead of simple pass–fail criteria,empirical data is employed to determine failure rate probabilities quantitatively and *** data,including breakdown,dissipation factor,and partial discharge mea-surements,are used to construct the Weibull distribution model to predict fault and failure rates and calculate hazard *** rigorous examinations interpreted through the analytical model help assess insulation system resilience and particularly the impact of electrical field stress and mica *** of electrical stress from 66.75 to 71.20 V/mil demonstrated how the mean time to failure of the system changed from 146.4 to 85.1 at 3 Un,hence identifying opportunities for design improvement and uncovering performance ***,the developed framework enhances comprehension of insulation system failure probabilities,guiding design decisions and ensuring a secure and reliable operation of electrical machines across applications.

关键词： insulation parametric approach

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