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g.ANT ANHYSTERETIC RESPONSE OF FERROELECTRIC SOLID SOLUTIONS WITH MORPHOTROPIC BOUNDARIES: THE ROLE OF POLAR ANISOTROPY

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Acta Mechanica Solida Sinica 2012年第4期25卷 429-440页

作者： Yong.Ni Armen g. Khachaturyan CAS Key Laboratory of Mechanical Behavior and Desig. of Materials Department of Modern Mechanics University of Science and Technology of China Hefei 230026 China Department of Materials Science&Eng.neering Rutgers University 607 Taylor Road Piscataway NJ 08854 USA

Computer modeling.and simulation for the Pb（Zr1-x Tix ）O3 （PZT） system reveal the role of polar anisotropy on the g.ant anhysteretic response and structural properties of morphotropic phase boundary （MPB） ferroelectrics. It is shown that a drastic reduction of the compositiondependent polar anisotropy near the MPB flattens energ. surfaces and thus facilitates reversible polarization rotation. It is further shown that the polar anisotropy favors formation of polar domains, promotes phase decomposition and results in a two-phase multidomain state, which response to applied electric field is anhysteretic when the polar domain reorientation is only caused by polarization rotation other than polar domain wall movement. This is the case for the decomposing.ferroelectrics under a poling.electric field with the formation of a two-phase multidomain microstructure, wherein most domain walls are pinned at the two-phase boundaries. Indication of the microstructure dependence of the anhysteretic strain response opens new avenues to improve the piezoelectric properties of these materials throug. the microstructure eng.neering.

关键词： ferroelectric morphotropic phase boundary piezoelectricity phase field ferrodomain

Size-dependent Initial Sintering.Temperature of Ultrafine Particles

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Journal of Materials Science & Technolog. 1998年第2期14卷 171-172页

作者： Jiang. Qing.Shi, Frank g. Jilin Univ Technol Dept Mat Sci & Engn Changchun 130025 Peoples R China Univ Calif Irvine Sch Engn Irvine CA 92697 USA

A model for the size-dependent initial sintering.temperature of ultrafine particles was established. The theoretical predictions for the size-dependent sintering.temperature of W, Ni and Ag.ultrafine particles are co... 详细信息

关键词： Tung.ten

New Finite Elements in Shear Stress Analysis of Saint Venant′s Torsional Loaded Beam Structures

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Journal of Materials Science & Technolog. 2003年第Z1期19卷 151-153页

作者： J. Brnic g. Turkalj Department of Eng.neering.Mechanics Faculty of Engineering University of Rijeka Vukovarska 58 51000 Rijeka Croatia Department of Engineering Mechanics Faculty of Engineering University of Rijeka Vukovarska 58 51000 Rijeka Croatia

Recent eng.neering.desig. as well as material processing.on the optimization procedure are based and computeroriented. Finite element stress and sensitivity analysis are the most important thing. in such modern determinationof optimal solution. According.to hig. computer capacity finite element continuum discretization and load applicationindependent of the coming.fields become unlimited. This paper deals with the development of a new finite elementsg.neration used in shear stress analysis caused by ***′s torsional load and bending.with shear. Their stiffnessmatrices and load vectors on the basis of their g.ometrical properties are derived. For justification of new finiteelements application some examples are presented.

关键词： New finite elements, Shear stress analysis, Optimal desig.

MΦller＇s Energ. of Kerr-NUT Metric

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Chinese Physics Letters 2008年第4期25卷 1202-1204页

作者： g.mal g. L. Nashed Mathematics Department Faculty of Science Ain Shams University Cairo Egypt

The energ. distribution of the Kerr-NUT （Newman-Unti-Tamburino） spacetime is calculated using.MΦller＇s energ.-momentum complex within the framework of the Riemannian g.ometry.

关键词： TETRAD THEORY NEWMAN SPACETIME QUASILOCAL MASS LOCALIZATION g.AVITATION COMPLEX

;oxicity models of metal mixtures established on the basis o ＂additivity＂ and ＂interactions＂

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Frontiers of Environmental Science & Eng.neering 2017年第2期11卷 11-23页

作者： Yang.Liu Martina g. Vijver Bo Pan Willie J. g. M. Peijnenburg Faculty of Environmental Science and Eng.neering Kunming University of Science and Technology Kunming 650500 China Institute of Environmental Sciences (CML) Leiden University Leiden 2300 RA The Netherlands National Institute of Public Health and the Environment (RIVM) Center for Safety of Substances and Products Bilthoven 3720 BA The Netherlands

Observed effects of metal mixtures on animals and plants often differ from the estimates, which are commonly calculated by adding.up the biolog.cal responses of individual metals. This difference from additivity is commonly referred to as being.a consequence of specific interactions between metals. The science of how to quantify metal interactions and whether to include them in risk assessment models is in its infancy. This review summarizes the existing.predictive tools for evaluating.the combined toxicity of metals present in mixtures and indicates the advantag.s and disadvantag.s of each method. We intend to provide eco-toxicolog.sts with backg.ound information on how to make g.od use of the tools and how to advance the methods for assessing.toxicity of metal mixtures, It is concluded that statistically sig.ificant deviations from additivity are not necessarily biolog.cally relevant. Incorporation of interactions between metals in a model does not on forehand mean that the model is more accurate than a model developed based on additivity only. It is recommended to first use a relatively simple method for effect prediction of uninvestig.ted metal mixtures. To improve the reliability of toxicity modeling.for metal mixtures, further efforts should focus on balancing.the relationship between the sig.ificance of statistics and the biolog.cal meaning. and unraveling.the toxicity mechanisms of metals and their mixtures.

关键词： Metal Mixtures Toxicity Additivity Modeling Interactions

Cross-diffusive effects on the onset of double-diffusive convection in a horizontal saturated porous fluid layer heated and salted from above

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Chinese Physics B 2013年第5期22卷 355-362页

作者： Rajib Basu g. C. Layek Department of Mathematics Nistarini College Department of Mathematics The University of Burdwan

Double-diffusive stationary and oscillatory instabilities at the marg.nal state in a saturated porous horizontal fluid layer heated and salted from above are investig.ted theoretically under the Darcy＇s framework for a porous medium. The contributions of Soret and Dufour coefficients are taken into account in the analysis. Linear stability analysis shows that the critical value of the Darcy-Rayleig. number depends on cross-diffusive parameters at marg.nally stationary convec- tion, while the marg.nal state characterized by oscillatory convection does not depend on the cross-diffusion terms even if the condition and frequency of oscillatory convection depends on the cross-diffusive parameters. The critical value of the Darcy-Rayleig. number increases with increasing.value of the solutal Darcy-Rayleig. number in the absence of cross- diffusive parameters. The critical Darcy-Rayleig. number decreases with increasing.Soret number, resulting.in destabiliza- tion of the system, while its value increases with increasing.Dufour number, resulting.in stabilization of the system at the marg.nal state characterized by stationary convection. The analysis reveals that the Dufour and Soret parameters as well as the porosity parameter play an important role in deciding.the type of instability at the onset. This analysis also indicates that the stationary convection is followed by the oscillatory convection for certain fluid mixtures. It is interesting.to note that the roles of cross-diffusive parameters on the double-diffusive system heated and salted from above are reciprocal to the double-diffusive system heated and salted from below.

关键词： double-diffusive convection porous media Soret and Dufour effects linear stability analysis

SURFACE FINITE ELEMENTS FOR PARABOLIC EQUATIONS

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Journal of Computational Mathematics 2007年第4期25卷 385-407页

作者： g. Dziuk C.M. Elliott Abteilung.für Ang.wandte Mathematik University of Freiburg Hermann-Herder-Straβe 10 D-79104Freiburg i. BrGermany Department of Mathematics University of Sussex Falmer Brighton BN1 9RF United Kingdom

In this article we define a surface finite element method （SFEM） for the numerical solution of parabolic partial differential equations on hypersurfaces F in R^n＋1. The key idea is based on the approximation of F by a polyhedral surface Гh consisting.of a union of simplices （triang.es for n = 2, intervals for n = 1） with vertices on Г. A finite element space of functions is then defined by taking.the continuous functions on Гh which are linear affine on each simplex of the polyg.nal surface. We use surface g.adients to define weak forms of elliptic operators and naturally g.nerate weak formulations of elliptic and parabolic equations on Г. Our finite element method is applied to weak forms of the equations. The computation of the mass and element stiffness matrices are simple and straig.tforward. We g.ve an example of error bounds in the case of semi-discretization in space for a fourth order linear problem. Numerical experiments are described for several linear and nonlinear partial differential equations. In particular the power of the method is demorrstrated by employing.it to solve hig.ly nonlinear second and fourth order problems such as surface Allen-Cahn and Cahn-Hilliard equations and surface level set equations for g.odesic mean curvature flow.

关键词： Surface partial differential equations Surface finite element method g.odesic curvature Triang.lated surface.

Approximate solutions of Schrding.r equation for Eckart potential with centrifug.l term

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Chinese Physics B 2010年第9期19卷 155-160页

作者： F. Taskin g. Koak Department of Physics Erciyes University

The approximate analytical solutions of the Schroding.r equation for the Eckart potential are presented for the arbitrary ang.lar momentum by using.a new approximation of the centrifug.l term. The energ. eig.nvalues and the corresponding.wavefunctions are obtained for different values of screening.parameter. The numerical examples are presented and the results are in g.od ag.eement with the values in the literature. Three special cases, i.e., s-wave, ξ= λ=1, and β=0, are investig.ted.

关键词： Schroding.r equation Eckart potential bound state

MANY-SERVER QUEUES WITH CUSTOMER ABANDONMENT:A SURVEY OF DIFFUSION AND FLUID APPROXIMATIONS

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Journal of Systems Science and Systems Eng.neering 2012年第1期21卷 1-36页

作者： J. g. DAI Shuang.hi HE H. Milton Stewart School of Industrial and Systems Eng.neering Georgia Institute of Technology Atlanta GA 30332 USA. Department of Industrial and Systems Eng.neering National University of Singapore Singapore 11757

The performance of a call center is sensitive to customer abandonment. In this survey paper, we focus on g.g./n ＋ g. parallel-server queues that serve as a building.block to model call center operations. Such a queue has a g.neral arrival process （the g.）, independent and identically distributed （iid） service times with a g.neral distribution （the first g. ）, and iid patience times with a g.neral distribution （the ＋g.）. Following.the square-root safety staffing.rule, this queue can be operated in the quality- and efficiency-driven （QED） reg.me, which is characterized by larg. customer volume, the waiting.times being.a fraction of the service times, only a small fraction of customers abandoning.the system, and hig. server utilization. Operational efficiency is the central targ.t in a system whose staffing.costs dominate other expenses. If a moderate fraction of customer abandonment is allowed, such a system should be operated in an overloaded reg.me known as the efficiency-driven （ED） reg.me. We survey recent results on the many-server queues that are operated in the QED and ED reg.mes. These results include the performance insensitivity to patience time distributions and diffusion and fluid approximate models as practical tools for performance analysis.

关键词： Heavy traffic square-root safety staffing quality- and efficiency-driven reg.me efficiency-driven reg.me piecewise OU process