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Effect of lattice distortion on solid solution strengthening of BCC high-entropy alloys

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Journal of Materials Science & Technology 2018年第2期34卷 349-354页

作者： Zhipeng Wang Qihong Fang jia Li Bin Liu yong Liu State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan University State Key Laboratory for Powder Metallurgy Central South University

An analytical model is established to study the influence of lattice distortion and fraction of Hf on the yield strength of the BCC TiNbTaZrHfx multi-component high entropy alloys （HEAs）. Meanwhile, the mechanism of solid solution strengthening caused by lattice distortion is also discussed in the HEA. The distorted unit cell is introduced to indicate the lattice distortion effects induced by the differences of the atomic size and shear modulus by doping other elements in Ti-based metal. The results show that the calculated values of the alloying yield strength considering the path of least resistance are obtained with regard to various grain sizes for the equiatomic TiNbTaZrHf HEA, which is well in line with the experimental results. Furthermore, it is predicted that the alloying yield strength is the largest value in the case of the same grain size for the Hf atomic fraction of 0.122. The meaningful modeling could provide a theoretical method to investigate the yield strength and alloying design of other BCC HEAs in the future.

关键词： High entropy alloy Solid solution strengthening Least resistance Yield strength Alloying design

A Detailed Study on the Equal Arrival Time Surface Effect in Gamma-Ray Burst Afterglows

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Chinese Journal of Astronomy and Astrophysics 2007年第3期7卷 397-404页

作者： yong-Feng Huang Ye Lu Anna Yuen lam Wong Kwong Sang Cheng Department of Astronomy Nanjing University Nanjing 210093 Department of Physics The University of Hong Kong Pokfulam Road Hong Kong National Astronomical Observatories Chinese Academy of Sciences Beijing 100012

Due to the relativistic motion of gamma-ray burst remnant and its deceleration in the circumburst medium, the equal arrival time surfaces at any moment are not spherical, rather, they are distorted ellipsoids. This will leave some imprints in the afterglows. We study the effect of equal arrival time surfaces numerically for various circumstances, i.e., isotropic fireballs, collimated jets, density jumps and energy injection events. For each case, a direct comparison is made between including and not including the effect. For isotropic fireballs and jets viewed on axis, the effect slightly hardens the spectra and postpones the peak time of the afterglows, but does not change the shapes of the spectra and light curves significantly. In the cases of a density jump or an energy injection, the effect smears out the variations in the afterglows markedly.

关键词： gamma rays bursts -- relativity -- shock waves -- ISM clouds

Atomic layer deposition of Al_2O_3 on porous polypropylene hollow fibers for enhanced membrane performances

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Chinese Journal of Chemical Engineering 2018年第4期26卷 695-700页

作者： Xiaojuan jia Zexian Low He Chen Sen Xiong yong Wang State Key Laboratory of Materials-Oriented Chemical Engineering Jiangsu National Synergetic Innovation Center for Advanced Materials and College of Chemical EngineeringNanjing Tech University Department of Chemical Engineering Monash University

Porous polypropylene hollow fiber(PPHF) membranes are widely used in liquid purification. However, the hydrophobicity of polypropylene(PP) has limited its applications in water treatment. Herein, we demonstrate that, for the first time, atomic layer deposition(ALD) is an effective strategy to conveniently upgrade the filtration performances of PPHF membranes. The chemical and morphological changes of the deposited PPHF membranes are characterized by spectral, compositional, microscopic characterizations and protein adsorption measurements. Al_2O_3 is distributed along the cross section of the PP hollow fibers, with decreasing concentration from the outer surface to the inner surface. The pore size of the outer surface can be easily turned by altering the ALD cycles. Interestingly, the hollow fibers become much more ductile after deposition as their elongation at break is increased more than six times after deposition with 100 cycles. The deposited membranes show simultaneously enhanced water permeance and retention after deposition with moderate ALD cycle *** instance, after 50 ALD cycles a 17% increase in water permeance and one-fold increase in BSA rejection are observed. Moreover, the PP membranes exhibit improved fouling-resistance after ALD deposition.

关键词： Polypropylene hollow fiber membranes Atomic layer deposition Alumina deposition Anti-fouling Surface modification

Investigation of Taylor-Gortler-like Vortices Using the Parallel Consistent Splitting Scheme

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Advances in Applied Mathematics and Mechanics 2009年第6期1卷 799-815页

作者： yong Hong Kuo Kawi-lam Wong Jeff Chak-Fu Wong The Joint Institute for Computational Sciences University of Tennessee/Oak Ridge National LaboratoryBuilding 5100RM 209Mail Stop 6013Bethel Valley RoadP.O.Box 2008 Oak RidgeTN 37831-6013 Department of Mathematics Room 220Lady Shaw BuildingThe Chinese University of Hong KongShatinHong KongChina

Symmetric Taylor-Gortler-like vortices at Re=3200 and 5000 in 3D rectangular cavities with a moving top lid are studied numerically and tested with a spanwise aspect ratio of 1:1:L,where L=1,2,*** are obtained by solving the momentum equations and the continuity equations using the consistent splitting *** code presented here was ported to the Parallel Interoperable Computational Mechanics System Simulator(PICMSS).Stable solutions are obtained as limit cases of the transients.

关键词： Mixed finite element consistent splitting scheme PICMSS

An Easily Implementable Algorithm for Efficient Projection onto the Ordered Weighted l_(1)Norm Ball

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Journal of the Operations Research Society of China 2023年第4期11卷 925-940页

作者： yong-Jin Liu jia-Jing Xu Lan-Yu Lin School of Mathematics and Statistics Fuzhou UniversityFuzhou350108FujianChina

This paper concerns with efficient projection onto the ordered weighted l_(1)norm ball,which is equivalent to the problem of finding projector onto the intersection of the monotone nonnegative cone and an affine *** on Lagrangian relaxation and secant approximation method,we propose an easily implementable yet efficient algorithm to solve the projection problem which is proved to terminate after a finite number of ***,we design efficient implementations for our algorithm and compare it with a semismooth Newton(SSN)algorithm and a root-finding(Root-F)*** results on a diversity of test problems show that our algorithm is superior than SSN and Root-F.

关键词： Lagrangian relaxation secant method ordered weighted l_(1)norm ball

Precipitation kinetics of complex precipitate in multicomponent systems

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Journal of Iron and Steel Research International 2018年第10期25卷 1086-1093页

作者： yong Yang Tian-rui Li Tao jia Zhao-dong Wang State Key Laboratory of Rolling and Automation Northeastern University Shenyang 110819 Liaoning China

A kinetic model based on the classical nucleation and growth theory has been proposed to predict the precipitation behavior of complex precipitate. The method for calculating absolute solution temperature, which is an important guidance for determining solution treatment temperature, is also proposed based on thermodynamic model. In the model, nucleation of the second phase is assumed to be controlled by the effective diffusion, which involves the bulk diffusion and dislocation pipe diffusion, and growth is controlled by the bulk diffusion of forming elements. The interfacial energy of complex precipitate is calculated by the linear interpolation method, and the effects of alloying elements on precipitation behavior are manifested using weighted means of their diffusivities and concentration. The predictions were compared with the experimental measurements, and a good agreement was obtained.

关键词： Complex precipitate Carbide Kinetic model Nucleation and growth theory Absolute solution temperature

Multiple parametric Marcinkiewicz integrals with mixed homogeneity along surfaces

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Applied Mathematics(A Journal of Chinese Universities) 2023年第3期38卷 413-428页

作者： SHEN jia-wei HE Shao-yong CHEN Jie-cheng Department of Mathematics Zhejiang Normal UniversityJinhua 321004China Department of Mathematics Huzhou UniversityHuzhou 313000China.

In this paper, the multiple parametric Marcinkiewicz integral operators with mixed homogeneity along surfaces are studied. The Lp-mapping properties for such operators are obtained under the rather weakened size conditions on the integral kernels both on the unit sphere and in the radial direction. The main results essentially improve and extend certain previous results.

关键词： parametric Marcinkiewicz integrals rough kernels mixed homogeneity product spaces

In situ reaction mechanism of MgAlON in Al–Al2O3–MgO composites at 1700°C under flowing N2

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International Journal of Minerals,Metallurgy and Materials 2017年第9期24卷 1061-1066页

作者： Shang-hao Tong yong Li Ming-wei Yan Peng jiang jia-jia Ma Dan-dan Yue School of Materials Science and Engineering University of Science and Technology BeijingBeijing 100083China

The Al–AlO–MgO composites with added aluminum contents of approximately 0wt%, 5wt%, and 10wt%, named as M, M, and M, respectively, were prepared at 1700°C for 5 h under a flowing Natmosphere using the reaction sintering method. After sintering, the Al–AlO–MgO composites were characterized and analyzed by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The results show that specimen Mwas composed of MgO and MgAlO. Compared with specimen M, specimens Mand Mpossessed MgAlON, and its production increased with increasing aluminum addition. Under an Natmosphere, MgO, AlO, and Al in the matrix of specimens Mand Mreacted to form MgAlON and AlN-polytypoids, which combined the particles and the matrix together and imparted the Al–AlO–MgO composites with a dense structure. The mechanism of MgAlON synthesis is described as follows. Under an Natmosphere, the partial pressure of oxygen is quite low; thus, when the Al–AlO–MgO composites were soaked at 580°C for an extended period, aluminum metal was transformed into AlN. With increasing temperature, AlOdiffused into AlN crystal lattices and formed AlN-polytypoids; however, MgO reacted with AlOto form MgAlO. When the temperature was greater than(1640 ± 10)°C, AlN diffused into AlOand formed spinel-structured AlON. In situ MgAlON was acquired through a solid-solution reaction between AlON and Mg AlOat high temperatures because of their similar spinel structures.

关键词： composites metal aluminum nitrogen atmosphere magnesium aluminum oxynitride reaction mechanism

Characterization of the globular oxide inclusion ratings in steel using laser-induced breakdown spectroscopy

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Frontiers of physics 2016年第6期11卷 273-279页

作者： yong Zhang Yun-Hai jia Chun Yang Dong-Ling Li jia Liu yong-Yan Chen Ying Liu Yi-Xiang Duan Research Center of Analytical Instrumentation Key Laboratory of Bio-Resource and Eco-Environment Ministry of Education College of Life Science Sichuan University Chengdu 610064 China Central Iron and Steel Research Institute Beijing 100081 China NCS Testing Technology Co. Ltd. Beijing 100094 China General Research Institute of Nonferrous Metals Beijing 100088 China

Grade assessment of steel is generally performed via the metallographic method, which is time-consuming and is not able to provide the elemental distribution information. In this paper, we present a method to measure the globular oxide inclusion ratings in steel using laser-induced breakdown spectroscopy (LIBS). The measurement is performed in two basic steps: steel samples are polished using metallographic sand paper and the Al2O3 inclusion number and size distribution in a marked area are observed using scanning electron microscope/energy dispersive X-ray spectroscopy (SEM/EDS) for further LIBS scanning analysis. The threshold intensity that distinguishes soluble aluminum and insoluble aluminum inclusions is determined using LIBS combined with the SEM/EDS statistical data. Carbon steel (the sample number is S9256) and bearing steel (the sample number is GCr15) are analyzed in scanning mode, and the number of Al2O3 inclusions in different size ranges is obtained from the statistical information derived from the Al2O3 size calibration curve. According to heavy and thin series for globular oxide inclusions grade assessment, the method we propose is comparable to the traditional metallographic method in terms of accuracy; however, the process is simplified and the measurement speed is significantly improved.

关键词： laser-induced breakdown spectroscopy (LIBS) globular oxide inclusion steel grade assessment elemental distribution