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Mechanical Behaviors of Ti-Si-N Coatings Deposited by Bias Sputtering

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稀有金属材料与工程 2012年第S1期41卷 18-23页

作者： p W Shum Advanced Coatings Applied Research Laboratory(ACARL) Department of Mechanical and Biomedical Engineering(MBE)City University of Hong KongHong KongChina

Ti-Si-N hard coatings were deposited on steel substrates by reactive unbalanced magnetron sputtering from Ti and Si elemental targets in a mixture of Ar and N2 *** influences of negative bias voltage(in the range of-30 to-80 V)on the mechanical properties of the coatings were *** particular,the critical cycle during dynamic impact tests was employed to indicate the bonding strength of the *** was found that the Ti-Si-N coatings prepared at lower constant bias voltages could effectively improve the adhesion and the cyclic impact performance,but their hardness was dropped significantly to 13 Gpa at a bias of-30 *** bias voltage values induced greater hardness.A maximum hardness of 47 Gpa was obtained at a bias of-60 ***,the coating adhesion was worse in this case,and the number of impact cycles(～8×10 3)that the coatings could endure was much shorter than that of TiN binary coatings(～2×104).On the other hand,the bias voltage was varied linearly from-40 to-60 V during Ti-Si-N *** this circumstance,the hardness of the coatings deposited with the bias-graded configuration remained very high(42 Gpa),and the adhesion strength was improved ***,the critical impact cycle could reach as high as 1.8×***,bias-graded deposition can provide an effective processing route to prepare Ti-Si-N superhard coatings with high adhesion strength and impact resistance.

关键词： Ti-Si-N coatings magnetron sputtering bias voltage mechanical properties impact test

Fractals and Spatial Statistics of point patterns

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Journal of Earth Science 2013年第1期24卷 1-11页

作者： Frederik p Agterberg Geological Survey of Canada 601 Booth Street Ottawa K1A 0E8 Canada

The relationship between fractal point pattern modeling and statistical methods of pa- rameter estimation in point-process modeling is reviewed. Statistical estimation of the cluster fractal dimension by using Ripley＇s K-function has advantages in comparison with the more commonly used methods of box-counting and cluster fractal dimension estimation because it corrects for edge effects, not only for rectangular study areas but also for study areas with curved boundaries determined by re- gional geology. Application of box-counting to estimate the fractal dimension of point patterns has the disadvantage that, in general, it is subject to relatively strong ＂roll-off＂ effects for smaller boxes. point patterns used for example in this paper are mainly for gold deposits in the Abitibi volcanic belt on the Canadian Shield. Additionally, it is proposed that, worldwide, the local point patterns of podiform Cr, volcanogenic massive sulphide and porphyry copper deposits, which are spatially distributed within irregularly shaped favorable tracts, satisfy the fractal clustering model with similar fractal dimensions. The problem of deposit size （metal tonnage） is also considered. Several examples are provided of cases in which the pareto distribution provides good results for the largest deposits in metal size-frequency distribution modeling.

关键词： fractal point pattern spatial statistics roll-off effect cluster dimension pareto distribution.

Magnetic polarization of a Mn-doped semiconductor nanostructure controlled by an external bias

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Journal of Semiconductors 2015年第7期36卷 22-28页

作者： p.paradeo Unstituto de Fisica Universidad Nacional Autonoma de Mexico

The interplay between the electric and magnetic properties in a double quantum well heterostructure doped by magnetic ions is theoretically investigated. In this material, the magnetism is mediated by the hole gas. The total magnetic polarization of the system is controllable by an external applied bias. The device has two equilibrium states （symmetric and antisymmetric configurations）. In the stable configuration （anti-ferromagnetic type）, the particle spin distribution is reversed in the adjacent wells. The stability of the system is investigated by simulating the interaction of the hole gas with the light. By using an ab initio method, we estimate the switching time of the device.

关键词： magnetic polarization quantum well stability

Experimental Investigation on Friction Welding of UNS S32205 Duplex Stainless Steel

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Acta Metallurgica Sinica(English Letters) 2014年第6期27卷 995-1007页

作者： p. M. Ajith p. Sathiya S. Aravindan Department of production Engineering National Institute of Technology Department of Mechanical Engineering Indian Institute of Technology Delhi

UNS S 32205 duplex stainless steel specimens were joined by continuous drive friction welding process. The experiments were conducted as per the Taguchi（L16 orthogonal array） method. The friction welding process parameters such as heating pressure, heating time, upsetting pressure, upsetting time, and speed of rotation were fixed with low,medium, and high levels of range based on the machine capacity, and the required knowledge was acquired from the preliminary experiments. The joint characterization studies included micro structural examination and evaluation of mechanical properties of the joints. Microhardness variation, impact toughness, and tensile strength of the joints were evaluated. Neither a crack nor an incomplete bonding zone was observed. The tensile strength of the joints was higher than the strength of the base material, and the friction and upsetting pressures were found to influence the joint strength. The tensile strength of all the welds was observed to be increasing with an increase in the rotational speed. The toughness of the friction welds was evaluated at room temperature and also at subzero（cryo） temperature conditions. The toughness for friction welds was found to be superior to the fusion welds of duplex stainless steel at room temperature and cryo conditions. Weldments exhibited better corrosion resistance than the parent material.

关键词： Duplex stainless steel Hardness Tensile strength Toughness Microstructure Corrosion

Cavitating/non-cavitating flows simulation by third-order finite volume scheme and power-law preconditioning method

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Applied Mathematics and Mechanics(English Edition) 2013年第2期34卷 209-228页

作者： p.AKBARZADEH School of Mechanical Engineering Shahrood University of Technology

Equations of steady inviscid and laminar flows are solved by means of a third-order finite volume （FV） scheme. For this purpose, a cell-centered discretization technique is employed. In this technique, the flow parameters at the cell faces are computed using a third-order weighted averages procedure. A fourth-order artificial dissipation is used for stability of the solution. In order to achieve the steady-state situation, four-step Runge-Kutta explicit time integration method is applied. An advanced progressive preconditioning method, named the power-law preconditioning method, is used for faster convergence. In this method, the preconditioning matrix is adjusted automatically from the velocity and/or pressure flow-field by a power-law relation. Attention is directed towards accuracy and convergence of the schemes. The results presented in the paper focus on steady inviscid and laminar flows around sheet-cavitating and fully-wetted bodies including hydrofoils and circular/elliptical cylinder. Excellent agreements are obtained when numerical predictions are compared with other available experimental and numerical results. In addition, it is found that using the power-law preconditioner significantly increases the numerical convergence speed.

关键词： power-law preconditioner finite-volume (FV) scheme third-order accuracy,convergence cavitation hydrofoil

Julia sets of permutable Holomorphic maps Dedicated to professor Sheng GONG on the occasion of his 75th birthday

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Science China Mathematics 2006年第11期49卷 1715-1721页

作者： SINGH Anand p Department of Mathematics University of Jammu Jammu-180006India

Let f and g be two permutable transcendental holomorphic maps in the *** shall discuss the dynamical properties of f, g and f o g and prove, among other things, that if either f has no wandering domains or f is of bou... 详细信息

关键词： Julia set, Fatou set, permutable maps.

DISCRETE GALERKIN METHOD FOR FRACTIONAL INTEGRO-DIFFERENTIAL EQUATIONS

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Acta Mathematica Scientia 2016年第2期36卷 560-578页

作者： p.MOKHTARY Department of Mathematics Faculty of Basic Sciences Sahand University of Technology

In this article, we develop a fully Discrete Galerkin（DG） method for solving ini- tial value fractional integro-differential equations（FIDEs）. We consider Generalized Jacobi polynomials（CJps） with indexes corresponding to the number of homogeneous initial conditions as natural basis functions for the approximate solution. The fractional derivatives are used in the Caputo sense. The numerical solvability of algebraic system obtained from implementation of proposed method for a special case of FIDEs is investigated. We also provide a suitable convergence analysis to approximate solutions under a more general regularity assumption on the exact solution. Numerical results are presented to demonstrate the effectiveness of the proposed method.

关键词： Fractional integro-differential equation(FIDE) Discrete Galerkin(DG) Generalized Jacobi polynomials(GJps) Caputo derivative

An accurately fast algorithm of calculating reflection/transmission coefficients

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Science China(physics,Mechanics & Astronomy) 2008年第7期51卷 823-846页

作者： CASTAGNA J p Department of Earth and Atmospheric Sciences University of Houston

For the boundary between transversely isotropic media with a vertical axis of symmetry (VTI media), the interface between a liquid and a VTI medium, and the free-surface of an elastic half-space of a VTI medium, an accurately fast algorithm was presented for calculating reflection/transmission (R/T) coefficients. Specially, the case of post-critical angle incidence was considered. Although we only performed the numerical calculation for the models of the VTI media, the calculated results can be extended to the models of transversely isotropic media with a horizontal axis of rotation symmetry (HTI media). Compared to previous work, this algorithm can be used not only for the calculation of R/T coefficients of the boundary between ellipsoidally anisotropic media, but also for that between generally anisotropic media, and the speed and accuracy of this algorithm are faster and higher. According to the anisotropic parameters of some rocks given by the published literature, we performed the calculation of R/T coefficients by using this algorithm and analyzed the effect of the rock anisotropy on R/T coefficients. We used Snell's law and the energy balance principle to perform verification for the calculated results.

关键词： reflection/transmission coefficient AVO analysis anisotropy VTI medium HTI medium

Existence and uniqueness results for mild solutions of random impulsive abstract neutral partial differential equation over real axis

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Applied Mathematics(A Journal of Chinese Universities) 2018年第1期33卷 71-87页

作者： p Indhumathi A Leelamani Department of Mathematics Tamilnadu College of Engineering Department of Mathematics Anna University Regional Centre

In this paper, we discuss the existence and uniqueness of mild solutions of random impulsive abstract neutral partial differential equations in a real separable Hilbert space. The results are obtained by using Leray-S... 详细信息

关键词： neutral equation Leray Schauder Alternative Banach Contraction principle semigroup of linear operators