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Microstructure and properties of hot extruded AZ31-0.25%Sb Mg-alloy

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中国有色金属学会会刊：英文版 2008年第A1期18卷 17-21页

作者：田素贵王岭 k.Y.ShON k.h.kIM School of Materials Sciences and Engineering Shenyang University of Technology Materials Engineering Department Korea Institute of Machinery and Materials

The effects of hot extrusion treatment on the microstructure and mechanical properties of AZ31-0.25%Sb Mg alloy were investigated by means of mechanical properties measurement and microstructure *** results show that the microstructure of AZ31-0.25%Sb Mg alloys consists ofα-Ms matrix,Mg_(17)Al_(12) and Mg_3Sb_2 *** ultimate tensile strength (UTS) and yield tensile strength(YTS) of the alloy are obviously enhanced by hot extrusion treatment,and the enhanced extent of UTS and YTS increases with the decrease of hot extrusion temperature,moreover,the YTS value of the alloy at RT,after extruded at 220℃,increases up to 131.4%,which attributes to the finer grains resulted from the dynamic recrystallization occurred during hot *** hot extrusion goes on,the slipping and concentration of dislocations continue to occur within the finer grains,which promotes the formation of the subgrains in the *** deformation features of the extruded alloy during tensile deformation at RT are the twinning deformation and dislocation slipping in the twinning ***,the deformation mechanisms of the alloy are a dislocation activation on the basal plane and a+c dislocation activation on the pyramidal planes.

关键词：镁合金高温挤压处理微观结构

Strong coupling,charm- and bottom-quark masses from electron-positron annihilation

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Chinese Physics C 2010年第6期34卷 675-679页

作者： J.h.kühn Institut für Theoretische Teilchenphysik Karlsruhe Institute of Technology

The cross section for electron-positron annihilation into hadrons allows for a precise determination of the strong coupling constant and the charm- and bottom-quark masses. Recent theoretical and experimental results ... 详细信息

关键词： strong coupling quark masses

Temperature distribution study during the friction stir welding process of Al2024-T3 aluminum alloy

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International Journal of Minerals,Metallurgy and Materials 2013年第8期20卷 779-787页

作者： Y.h.Yau A.hussain R.k.Lalwani h.k.Chan N.hakimi Department of Mechanical Engineering University of Malaya50603 KLMalaysia

heat flux characteristics are critical to good quality welding obtained in the important engineering alloy A12024- T3 by the friction stir welding （FSW） process. In the present study, thermocouples in three different configurations were amxed on the welding samples to measure the temperatures： in the first configuration, four thermocouples were placed at equivalent positions along one side of the welding direction; the second configuration involved two equivalent thermocouple locations on either side of the welding path; while the third configuration had all the thermocouples on one side of the layout but with unequal gaps from the welding line. A three-dimensional, non-linear ANSYS computational model, based on an approach applied to A12024-T3 for the first time, was used to simulate the welding temperature profiles obtained experimentally. The experimental thermal profiles on the whole were found to be in agreement with those calculated by the ANSYS model. The broad agreement between the two kinds of profiles validates the basis for derivation of the simulation model and provides an approach for the FSW simulation in A12024-T3 and is potentially more useful than models derived previously.

关键词： aluminum alloys friction stir welding welds temperature distribution

SUPPORTING AND SEPARATING SUBSETS FOR INVEX BODIES

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Acta Mathematica Scientia 2008年第4期28卷 818-822页

作者： h.k.El-Sayied Mathematics Department Faculty of ScienceTanta University

Invex bodies represent an important class of bodies which are considered as a generalization of convex *** this article,the author studies the supporting for this class of bodies as well as the separating subsets of t... 详细信息

关键词： Invex bodies focal points-supporting separating

Advanced prediction of organic–metal interactions through DFT study and electrochemical displacement approach

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Journal of Magnesium and Alloys 2023年第1期11卷 301-316页

作者： Abdelkarim Chaouiki Wail Al Zoubi Young Gun ko Materials Electrochemistry Group School of Materials Science and EngineeringYeungnam UniversityGyeongsan 38541South Korea

heterocyclic compounds are the promising biological compounds as nature-friendly for the corrosion protection of metallic *** this work,three heterocyclic compounds such as 1-azanaphthalene-8-ol(8-AN),2-methylquinoline-8-ol(8-MQ),and 8-quinolinol-5-sulfonic acid(8-QSA)were used as green compounds,and their anti-corrosion performance for AZ31 Mg in saline water was discussed on the basis of impedance interpretation and surface *** found that the electrochemical performance was improved in the order of 8-AN>8-MQ>8-QSA,demonstrating the electron donor effect of N-heterocycles to form coordination complexes on the magnesium *** the electrochemical performance,the protective layer constructed at the optimal concentration reinforces the barrier against aggressive environments,with potential inhibition efficiency of 87.4%,99.0%,and 99.9%for 8-QSA,8-MQ,and 8-AN,*** chemical parameters and electron density distribution for free organic species in the absence and presence of Mg^(2+)cation were evaluated using density functional theory(DFT).Upon the formation of coordination complexes between organic compound and Mg^(2+),energy gap underwent change about ΔE=5.7 eV in the 8-AN/Mg^(2+)***,the adsorption of heterocyclic compounds on Mg surface reveals the formation of strong covalent bonds with Mg atoms,which further confirmed by the electron density difference and projected density of states *** on theoretical calculations,three inhibitors can adsorb on the metal surface in both parallel and perpendicular orientations via C,O and N *** the parallel configuration,the C-Mg,N-Mg and O-Mg bond distances are between 2.11 and 2.25˚A,whereas the distances in the case of perpendicular adsorption are between 2.20 and 2.40˚A(covalent bonds via O and N atoms).The results indicated that parallel configurations are energetically more stable,in which the adsorption energies are-4.48 eV(8-AN),-4.28 eV(8-MQ)and-3.82 e

关键词： Organic layer heterocyclic compounds Electrochemical behavior DFT modeling

Effects of temperature-dependent viscosity variation on entropy generation, heat and fluid flow through a porous-saturated duct of rectangular cross-section

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Applied Mathematics and Mechanics(English Edition) 2007年第1期28卷 69-78页

作者： k.hooman h.Gurgenci School of Engineering the University of Queensland Brisbane Australia

Effect of temperature-dependent viscosity on fully developed forced convection in a duct of rectangular cross-section occupied by a fluid-saturated porous medium is investigated analytically. The Darcy flow model is applied and the viscosity-temperature relation is assumed to be an inverse-linear one. The case of uniform heat flux on the walls, i.e. the h boundary condition in the terminology of kays and Crawford [12], is treated. For the case of a fluid whose viscosity decreases with temperature, it is found that the effect of the variation is to increase the Nusselt number for heated walls. having found the velocity and the temperature distribution, the second law of thermodynamics is invoked to find the local and average entropy generation rate. Expressions for the entropy generation rate, the Bejan number, the heat transfer irreversibility, and the fluid flow irreversibility are presented in terms of the Brinkman number, the Péclet number, the viscosity variation number, the dimensionless wall heat flux, and the aspect ratio （width to height ratio）. These expressions let a parametric study of the problem based on which it is observed that the entropy generated due to flow in a duct of square cross-section is more than those of rectangular counterparts while increasing the aspect ratio decreases the entropy generation rate similar to what previously reported for the clear flow case by Ratts and Rant [14].

关键词： entropy generation rate forced convection porous medium rectangular duct temperature-dependent viscosity

Petrology and Geochemistry of Post-Collisional Early Miocene Volcanism in the karacadag Area(Central Anatolia,Turkey)

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Acta Geologica Sinica(English Edition) 2011年第5期85卷 1100-1117页

作者： krsad ASAN hseyin kURT Department of Geological Engineering Selcuk University

Early Miocene（ca.21-18 Ma） volcanism in the karacadag area comprises three groups of volcanic rocks:（1） calcalkaline suite（andesitic to rhyolitic lavas and their pyroclastics）,（2） mildly-alkaline suite（alkali basalt,hawaiite,mugearite,benmoreite and trachydacite）,and（3） a single trachyandesitic flow *** observations,40Ar/39Ar ages and geochemical data show that there was a progressive temporal transition from group 1 to 3 in a post-collisional tectonic *** calcalkaline suite rocks with medium-k in composition resemble those of subduction-related lavas, whereas the mildly-alkaline suite rocks having a sodic tendency（Na2O/k2O=l.5-3.2） resemble those of within-plate *** element and Sr-Nd isotopic characteristics of the suites suggest that the lithospheric mantle beneath the karacadag area was heterogeneously enriched by two processes before collision:（1） enrichment by subduction-related processes,which is important in the genesis of the calcalkaline volcanism,（2） enrichment by small degree melts from the astenosphere,which dominates the mildly alkaline *** of the enriched lithosphere by either delamination following collision and uplift or removal of the subducted slab following subduction and collision（i.e.,slab breakoff） is the likely mechanism for the initiation of the post-collision volcanism.

关键词： post-collision calcalkaline Sr-Nd isotopes karacadag Central Anatolia

ANALYSIS OF A COMPRESSIBLE GAS-LIQUID MODEL MOTIVATED BY OIL WELL CONTROL OPERATIONS

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Acta Mathematica Scientia 2012年第1期32卷 295-314页

作者： Steinar Evje k.h.karlsen Faculty of Science and Technology University of Stavanger Centre of Mathematics for Applications University of Oslo

We are interested in a viscous two-phase gas-liquid mixture model relevant for modeling of well control operations within the petroleum industry. We focus on a simplified mixture model and provide an existence result within an appropriate class of weak solutions. We demonstrate that upper and lower limits can be obtained for the gas and liquid masses which ensure that transition to single-phase regions do not occur. This is used together with appropriate a prior estimates to obtain convergence to a weak solution for a sequence of approximate solutions corresponding to mollified initial data. Moreover, by imposing an additional regularity condition on the initial masses, a uniqueness result is obtained. The framework herein seems useful for further investigations of more realistic versions of the gas-liquid model that take into account different flow regimes.

关键词： gas-liquid two-phase model weak solution existence uniqueness

An Analysis of the Invariance and Conservation Laws of Some Classes of Nonlinear Ostrovsky Equations and Related Systems

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Chinese Physics Letters 2011年第1期28卷 1-4页

作者： k. Fakhar A. h. kara Department of Mathematics Faculty of Science Universiti Teknologi Malaysia 81310 UTM Skudai Johor Malaysia School of Mathematics and Centre for Differential Equations Continuum Mechanics and Applications University of the Witwatersrand Johannesburg P Bag 3 Wits 2050 South Africa

A large class of partial differential equations in the modelling of ocean waves are due to Ostrovsky. We determine the invariance properties （through the Lie point symmetry generators） and construct classes of conservation laws for some of the models. In the latter case, the method involves finding the ＇multipliers＇ associated with the conservation laws with a stronger emphasis on the ＇higher-order＇ ones. The relationship between the symmetries and conservation laws is investigated by considering the invariance properties of the multipliers.

关键词： Mathematical physics Statistical physics and nonlinear systems