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rheological behavior,microstructure and hardness of A356 aluminum alloy in semisolid state using backward extrusion process

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中国有色金属学会会刊：英文版 2010年第S3期20卷 906-910页

作者： S.A.SADOUGH M.r.rAHMANI V.POUYAFAr Center of Excellence in Termoelasticity Amir Kabir University of Technology Department of Mechanical Engineering Islamic Azad University Science and Research Branch

The influence of temperature on the flow behavior and rheological characteristics of an A356 alloy in the semi-solid state was investigated using backward extrusion *** were performed at 5 temperatures and 4 different wall *** were determined using the force-displacement graphs obtained form back extrusion *** observed experimentally,at a constant temperature,the increase of shear rate results in the decrease of alloy viscosity *** the temperature increases the liquid fraction hence reduces the semi-solid alloy *** and image analyses show that,because of low forming speed,liquid has time to escape from solid phase forward the sample *** condition is the main reason for the segregation phenomenon seen in the base and *** hardness test on samples reveals that the hardness increases with the decrease of temperature and wall thickness.

关键词： aluminum alloy A356 backward extrusion semisolid forming rheology

Natural Convection of Fe_3O_4-Ethylene Glycol Nanofluid under the Impact of Electric Field in a Porous Enclosure

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Communications in Theoretical Physics 2018年第6期69卷 667-675页

作者： M.Sheikholeslami S.A.Shehzad r.Kumar Department of Mechanical Engineering Babol Noshirvani University of Technology Department of Mathematics COMSATS Institute of Information Technology Department of Mathematics Central University of Himachal Pardesh

Free convection of Fe_3O_4-Ethylene glycol nanofluid in existence of Coulomb forces is studied. Effect of thermal radiation is taken into account. Properties of nanofluid are varied with supplied voltage and shape of nanoparticles. The bottom wall is considered as positive electrode. Control Volume based Finite Element Method is used to obtain the results, which are the roles of Darcy number(Da), radiation parameter(rd), rayleigh number(ra), nanofluid volume fraction(φ), and supplied voltage(?φ). results indicate that Nusselt number is an enhancing function of supplied voltage and Darcy number. Maximum values for temperature gradient are occurred for platelet shape nanoparticles.

关键词：乙二醇 Fe3O4 乙烯对流传送电场围场多孔

Physical properties of lunar craters

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research in Astronomy and Astrophysics 2017年第3期17卷 23-38页

作者： Maitri P. Joshi Kushal r Bhatt rajmal Jain Shri Maneklal M.Patel Institute of Sciences and research Kadi Sarva VishwavidhyalayaGandhinagar-382015India

The surface of the Moon is highly cratered due to impacts of meteorites, asteroids, comets and other celestial objects. The origin, size, structure, age and composition vary among craters. We study a total of 339 craters observed by the Lunar reconnaissance Orbiter Camera （LrOC）. Out of these 339 craters, 214 craters are known （named craters included in the IAU Gazetteer of Planetary Nomenclature） and 125 craters are unknown （craters that are not named and objects that are absent in the IAU Gazetteer）. We employ images taken by LrOC at the North and South Poles and near side of the Moon. We report for the first time the study of unknown craters, while we also review the study of known craters conducted earlier by previous researchers. Our study is focused on measurements of diameter, depth, latitude and longitude of each crater for both known and unknown craters. The diameter measurements are based on considering the Moon to be a spherical body. The LrOC website also provides a plot which enables us to measure the depth and diameter. We found that out of 214 known craters, 161 craters follow a linear relationship between depth （d） and diameter （D）, but 53 craters do not follow this linear relationship. We study physical dimensions of these 53 craters and found that either the depth does not change significantly with diameter or the depths are extremely high relative to diameter （conical）. Similarly, out of 125 unknown craters, 78 craters follow the linear relationship between depth （d） and diameter （D） but 47 craters do not follow the linear relationship. We propose that the craters following the scaling law of depth and diameter, also popularly known as the linear relationship between d and D, are formed by the impact of meteorites having heavy metals with larger dimension, while those with larger diameter but less depth are formed by meteorites/celestial objects having low density material but larger diameter. The craters with very high depth and with very small d

关键词： Moon meteorites meteors meteoroids- planets and satellites: surfaces

Impact analysis of compressor rotor blades of an aircraft engine

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Frontiers of Structural and Civil Engineering 2019年第3期13卷 505-514页

作者： Y B SUDHIr SASTrY B G KIrOS F HAILU r BUDArAPU Department of Aeronautical Engineering Institute of Aeronautical EngineeringDundigalHyderabad 500043India Department of Aeronautical Engineering College of EngineeringDefense UniversityBishoftu 1041Ethiopia School of Mechanical Sciences Indian Institute of Technology BhubaneswarBhubaneswar 752050India

Frequent failures due to foreign particle impacts are observed in compressor blades of the interceptor fighter MIG-23 aircraft engines in the Ethiopian air force,supplied by the Dejen Aviation *** this paper,we made an attempt to identify the causes of failure and hence recommend the suitable materials to withstand the foreign particle *** and stress analysis of one of the recently failed MIG-23 gas turbine compressor blades made up of the following Aluminum based alloys:6061-T6,7075-T6,and 2024-T4,has been performed,apart from the impact analysis of the rotor blades hit by a granite *** numerical results are correlated to the practical *** on the modal,stress and impact analysis and the material properties of the three considered alloys,alloy 7075-T6 has been recommended as the blade material.

关键词： axial flow compressor rotor and stator blades aircraft engine stress and impact analysis aluminum alloys

A Novel Two Domain-Fusion Protein in Cyanobacteria with Similarity to the CAB/ELIP/HLIP Superfamily： Evolutionary Implications and regulation

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Molecular Plant 2008年第1期1卷 155-166页

作者： Oliver Kilian Anne Soisig Steunou Arthur r. Grossman Devaki Bhaya Department of Plant Biology The Carnegie Institution Stanford CA 94305 USA

Vascular plants contain abundant, light-harvesting complexes in the thylakoid membrane that are non-covalently associated with chlorophylls and carotenoids. These light-harvesting chlorophyll a/b binding （LHC） proteins are members of an extended CAB/ELIP/HLIP superfamily of distantly related polypeptides, which have between one and four transmembrane helices （TMH）. This superfamUy includes the single TMH, high-light-inducible proteins （Hlips）, found in cyanobacteria that are induced by various stress conditions, including high light, and are considered ancestral to the LHC proteins. The roles of, and evolutionary relationships between, these superfamily members are of particular interest, since they function in both light harvesting and photoprotection and may have evolved through tandem gene duplication and fusion events. We have investigated the Hlips （hli gene family） in the thermophilic unicellular cyanobacterium Synechococcus OS-B＇. The five hli genes present on the genome of Synechococcus OS-B＂ are relatively similar, but transcript analyses indicate that there are different patterns of transcript accumulation when the cells are exposed to various growth conditions, suggesting that different Hlips may have specific functions. Hlip5 has an additional TMH at the N-terminus as a result of a novel fusion event. This additional TMH is very similar to a conserved hypothetical, single membrane-spanning polypeptide present in most cyanobacteria. The evolutionary significance of these results is discussed.

关键词： light-harvesting chlorophyll a/b binding (LHC) transmembrane helices (TMH) high-light-inducible proteins (Hlips)

Numerical Simulation of Coupled Nonlinear Schrodinger Equations Using the Generalized Differential Quadrature Method

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Chinese Physics Letters 2011年第2期28卷 5-8页

作者： r.Mokhtari A.Samadi Toodar N.G.Chegini Department of Mathematical Sciences Isfahan University of TechnologyIsfahan 84156-83111Iran Department of Mathematics Tafresh UniversityTafresh 39518-79611Iran

We the extend application of the generalized differential quadrature method(GDQM)to solve some coupled nonlinear Schr(o)dinger *** cosine-based GDQM is employed and the obtained system of ordinary differential equations is solved via the fourth order runge-Kutta *** numerical solutions coincide with the exact solutions in desired machine precision and invariant quantities are conserved *** comparisons with the methods applied in the literature are carried out.

关键词： method invariant ordinary

red-emitting CaWO4:Eu^(3+),Tm^(3+)phosphor for solid-state lighting:Luminescent properties and morphology evolution

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Journal of rare Earths 2022年第2期40卷 226-233,I0002页

作者： L.X.Lovisa I.M.P.da Silva A.A.G.Santiago M.Siu Li E.Longo C.A.Paskocimas M.r.D.Bomio F.V.Motta Institute of Physics and Chemistry.Federal University of Itajubd(UNIFEI) ItajubdMG37500-903Brazil LSQM-Laboratory of Chemical Synthesis of Materials-Department of Materials Engineering Federal University of Rio Grande Do NorteP.O.Box 152459078-900Natal RNBrazil IFSC USPAv.Trabalhador Sao Carlense400CEP 13566-590Sao CarlosSPBrazil CDMF-LIEC UFSCarP.O.Box 67613565-905Sao Carlos.SPBrazil

CaWO_(4):xEu^(3+),yTm^(3+)crystals were obtained by facile synthesis at low temperature by the microwaveassisted hydrothermal method(MAH).The phase formation,morphology,luminescent properties and ene rgy transfer were *** X-ray diffraction(XrD)re sults show the formation of a scheelitelike tetragonal structure without the presence of secondary *** growth mechanism of hierarchical micro structures based on self-assembly and Ostwald-ripening processes was evaluated,obtaining different types of *** luminescence spectra of CaWO_(4):Eu^(3+),Tm^(3+)at 325 nm excitation show the predominance of red emission at the 5 D0→7 F2(Eu^(3+))transition at 624 *** feature signals dominant behavior of the electric dipole *** presence of Tm^(3+)is notably evident in the absorption spectra by the related excitation transitions:3 H6→1 G4,3 H6→3 F3 and 3 H6→3 *** parameters are discussed to characterize CaWO_(4):Eu^(3+),Tm^(3+)*** study of the emission spectrum as a function of the concentration of Eu^(3+)(x mol%)and Tm^(3+)(y mol%)indicates that the CaWO_(4):Eu^(3+),Tm^(3+)phosphors show stronger red emission intensity and exhibit the CIE value of x=0.63 and y=*** photoluminescence results show 97%high color purity for CaWO_(4):4 mol%Eu^(3+),a high CrI(92%)and a low CCT of 1085 *** results demonstrate that the CaWO_(4):Eu^(3+),Tm^(3+)red phosphors are promising as color converters for application in white light-emitting diodes and display devices.

关键词： CaWO_(4):Eu^(3+),Tm^(3+)microwave-assisted hydrothermal method Photoluminescence red phosphor rare earths

Thermophysical properties of iridium at finite temperature

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Chinese Physics B 2016年第11期25卷 404-411页

作者： Priyank Kumar N K Bhatt P r Vyas V B Gohel Department of Science Government PolytechnicGandhinagar Department of Physics Sardar Patel University Department of Physics School of Science Gujarat University

The bulk properties of materials in an extreme environment such as high temperature and high pressure can be understood by studying anharmonic effects due to the vibration of lattice ions and thermally excited *** this spirit,in the present paper,anharmonic effects are studied by using the recently proposed mean-field potential（MFP） approach and Mermin functional which arise due to the vibration of lattice ions and thermally excited electrons,*** MFP experienced by a wanderer atom in the presence of surrounding atoms is constructed in terms of cold energy using the local form of the *** have calculated the temperature variation of several thermophysical properties in an extreme environment up to melting *** results of our calculations are in excellent agreement with the experimental findings as well as the theoretical results obtained by using first principle *** conclude that presently used conjunction scheme（MFP＋pseudo potential） is simple computationally,transparent physically,and accurate in the sense that the results generated are comparable and sometimes better than the results obtained by first principle *** pseudopotential used is transferable to extreme environment without adjusting its parameters.

关键词： extreme experienced melting presently excited thermally sometimes understood comparable conclude

Free vibration and critical speed of moderately thick rotating laminated composite conical shell using generalized differential quadrature method

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Applied Mathematics and Mechanics(English Edition) 2013年第4期34卷 437-456页

作者： K.DANESHJOU M.TALEBITOOTI r.TALEBITOOTI School of Mechanical Engineering Iran University of Science and Technology School of Automotive Engineering Iran University of Science and Technology

The generalized differential quadrature method （GDQM） is employed to con- sider the free vibration and critical speed of moderately thick rotating laminated compos- ite conical shells with different boundary conditions developed from the first-order shear deformation theory （FSDT）. The equations of motion are obtained applying Hamilton＇s concept, which contain the influence of the centrifugal force, the Coriolis acceleration, and the preliminary hoop stress. In addition, the axial load is applied to the conical shell as a ratio of the global critical buckling load. The governing partial differential equations are given in the expressions of five components of displacement related to the points ly- ing on the reference surface of the shell. Afterward, the governing differential equations are converted into a group of algebraic equations by using the GDQM. The outcomes are achieved considering the effects of stacking sequences, thickness of the shell, rotating velocities, half-vertex cone angle, and boundary conditions. Furthermore, the outcomes indicate that the rate of the convergence of frequencies is swift, and the numerical tech- nique is superior stable. Three comparisons between the selected outcomes and those of other research are accomplished, and excellent agreement is achieved.

关键词： generalized differential quadrature method (GDQM) natural frequency,rotating conical shell first-order shear deformation theory (FSDT) critical speed