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Rare earth elements of fly ash from Wyoming’s Powder River Basin coal

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Journal of Rare Earths 2020年第2期38卷 219-226页

作者： zaixing huang Maohong Fan Hanjing Tian Department of Chemical and Petroleum Engineering University of WyomingWY 82071USA School of Civil and Environmental Engineering Georgia Institute of TechnologyGA 30332USA Department of Chemical Engineering West Virginia UniversityWV 26506USA

The advancement and increasing interests in green energy production and environmental protection technologies have spurred the demand for rare earth *** the other hand,the *** to rely 100% on import of these materials as the industry was crashed because of the environmental issues associated with mining and processing,and more importantly lack *** rare earth elements have many applications in defense and national security sectors,some of the elements were listed as strategic materials or critical materials because of the uncertainties in supply and ***,it has become imperative in searching for alternative resources for supplying rare earth elements including unconventional *** the strong incentive,coal fly ash is identified as one of the candidates among *** this study,we present rare earth element data for the 42 ash samples(all derived from Powder River Basin coal) that we collected from seven states(UT,WY,10,WI,ND,CO,and MI) representing 158 million tons of fly *** results indicate scattered distributions of rare earth elements with concentration ranging from 156 to 590 ppm although all the ash samples originated from the same coal basin(Powder River Basin).The rare earth element resource in these ashes is estimated between 74000 and 106000 *** ash samples were also characterized by elemental analysis,XRD,SEM-EDS and BET surface *** characterizations of the ashes were discussed as they might have implications in the subsequent rare earth element extraction *** summary,fly ash may represent a potential resource for rare earth element production.

关键词： Rare earth elements Coal fly ash XRD SEM-EDS BET surface area Critical materials

Geometric effects of cross sections on equilibrium of helical and twisted ribbon

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Applied Mathematics and Mechanics(English Edition) 2017年第4期38卷 495-504页

作者： Ye XIAO zaixing huang State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and Astronautics Nanjing 210016 China

In the framework of elastic rod model, the Euler-Lagrange equations characterizing the equilibrium configuration of the polymer chain are derived from a free energy functional associated with the curvature, torsion, twisting angle, and its derivative with respect to the arc-length. The configurations of the helical ribbons with different cross-sectional shapes are given. The effects of the elastic properties, the cross-sectional shapes, and the intrinsic twisting on the helical ribbons are discussed. The results show that the pitch angle of the helical ribbon decreases with the increase in the ratio of the twisting rigidity to the bending rigidity and approaches the intrinsic twisting. If the bending rigidity is much greater than the twisting rigidity, the bending and twisting of the helical ribbon always appear simultaneously.

关键词： Euler-Lagrange equation twisting angle pitch angle elastic rod model helical and twisted ribbon

A Possible Reason About Origin of Singularity and Anomalous Dispersion in Peridynamics

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Computer Modeling in Engineering & Sciences 2019年第11期121卷 385-398页

作者： Xinfeng Wang zaixing huang State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and AstronauticsNanjing210016China

In the benchmark problems of peridynamics,there are some eccentric results,for example,singularity of uniaxial tension and anomalous dispersion of *** reasons to give rise to these results are *** calculated local tension and wave of an infinite rod after adding a divergence of local stress in the peridynamic motion *** acquired results verify that the singularity in the peridynamic solution of local tension problem and anomalous dispersion of peridynamic wave are all ***,the anomalous features of some peridynamic solutions likely stem from the lack of local stress characterizing contact interactions.

关键词： Peridynamics singularity of displacement anomalous dispersion peridynamic wave

Investigation on coaxial stability of nano-bearing under two axis-deviation perturbations

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Science China(Physics,Mechanics & Astronomy) 2010年第12期53卷 2274-2283页

作者： YAO Yin huang zaixing College of Aerospace Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China

A spatial cylindrical model on nano-bearing constructed by double-walled carbon nano-tube (DWCNT) is established. Two motion equations are advanced to characterize the eccentric and deflective mode of the nano-bearing, respectively. On the basis of these equations, the coaxial stability of the nano-bearing under two axis-deviation perturbations is investigated. A characteristic parameter λ * governing the coaxial stability of the nano-bearing is determined. The influences of the angular velocity, interlayer spacing and axial length of the nano-bearing on the characteristic parameter λ * are analyzed and discussed in detail. It is found that when the angular velocity or interlayer spacing is smaller than a certain critical value, the parameter λ * keeps negative, and the coaxial stability of the nano-bearing is maintained. However, the axial length has very insignificant influence on λ * . In addition, for the two non-coaxial modes, the eccentric mode occurs more easily than the deflective one. The results of this paper provide a further insight into the coaxial stability of nano-bearing via the spatial model.

关键词： nano-bearing coaxial stability eccentric mode deflective mode

Coal and coal byproducts:A large and developable unconventional resource for critical materials—Rare earth elements

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Journal of Rare Earths 2018年第4期36卷 337-338页

作者： zaixing huang Maohong Fan Hanjing Tiand Department of Petroleum Engineering University of Wyoming Department of Chemical Engineering University of Wyoming School of Energy Resources University of Wyoming Department of Chemical Engineering West Virginia University

Rare earth elements（REEs） are critical materials and provide significant values to national security,energy production, environmental protection and economic growth. The supply of REEs in U.S. solely relies on import as domestic production of REEs was ceased because of the environmental concerns during mining and lack of competitiveness. Nonetheless, unconventional REEs-containing resources,including produced water. acid mine drainage, and coal and coal byproducts（C＆CBs） contain significant amounts of REEs. However, the concentrations of REEs in these resources are several orders of magnitude lower than that of REEs ores. Thus, extraction of REEs from these materials is challenging. Here we report REEs extraction with environmentally friendly method that successfully concentrated REEs from312 ppm in fly ash to 99.4% in the final product. Especially, the five critically important REEs（Dy, Eu, ***. and Y） account for up to ～63% of the total weight of all REEs in the final 99.4%-purity product. Coal fly ash is one of the major solid coal utilization byproducts, representing great potential resources for REEs extraction. Extraction of REEs from these unconventional resources could be the way to secure domestic supply of these critical materials.

关键词： Rare earth elements(REEs) REE oxides(REEOs) Coal and coal byproducts Critical materials

The singularity in the state-based peridynamic solution of uniaxial tension

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Theoretical & Applied Mechanics Letters 2018年第5期8卷 351-354,363页

作者： zaixing huang State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and Astronautics

We solve the local uniaxial tension of an infinite rod in the framework of non-ordinary state-based *** singular solutions of stress and displacement are *** the influencing range of the window function approaches zero,these two solutions will return to the solutions of the classical *** analysis shows that the singularities of the solutions stem from such a feature of the window function that must be represented by a rapidly decreasing function in *** to the classical elasticity,the stress solution of peridynamics is smoother than the displacement *** addition,a criterion used to select the window function is proposed in this paper.

关键词： Peridynmics Non-ordinary state-based peridynamics Singularity Local uniaxial tension Analytical solution

Peridynamic Study on Fracture Mode and Crack Propagation Path of a Plate with Multiple Cracks Subjected to Uniaxial Tension

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Computer Modeling in Engineering & Sciences 2023年第12期137卷 2593-2620页

作者： Zeyuan Zhou Ming Yu Xinfeng Wang zaixing huang State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and AstronauticsNanjing210016Chin

How to simulate fracture mode and crack propagation path in a plate with multiple cracks is an attractive but difficult issue in fracture *** is a recently developed nonlocal continuum formulation that can spontaneously predict the crack nucleation,branch and propagation in materials and structures through a meshfree discrete *** this paper,the peridynamic motion equation with boundary traction is improved by simplifying the boundary transfer *** calculate the critical cracking load and the fracture angles of the plate with multiple cracks under uniaxial *** results are consistent with those predicted by classical fracture *** fracture mode and crack propagation path are also *** calculation shows that the brittle fracture process of the plate with multiple cracks can be conveniently and correctly simulated by the peridynamic motion equation with boundary conditions.

关键词： Peridynamics multiple cracks brittle fracture crack propagation

Interfacial behavior of a thermoelectric film bonded to a graded substrate

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Applied Mathematics and Mechanics(English Edition) 2023年第11期44卷 1853-1870页

作者： Juan PENG Dengke LI zaixing huang Guangjian PENG Peijian CHEN Shaohua CHEN School of Materials Science and Physics State Key Laboratory for Geomechanics and Deep Underground EngineeringSchool of Mechanics and Civil EngineeringChina University of Mining and TechnologyXuzhou 221116Jiangsu ProvinceChina State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and AstronauticsNanjing 210016China College of Mechanical Engineering Zhejiang University of TechnologyHangzhou 310014China State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China Institute of Advanced Structure Technology Beijing Institute of TechnologyBeijing 100081China Beijing Key Laboratory of Lightweight Multi-functional Composite Materials and Structures Beijing Institute of TechnologyBeijing 100081China Collaborative Innovation Center of Electric Vehicles in Beijing Beijing Institute of TechnologyBeijing 100081China

To improve the thermoelectric converting performance in applications such as power generation,reutilization of heat energy,refrigeration,and ultrasensitive sensors in scramjet engines,a thermoelectric film/substrate system is widely designed and applied,whose interfacial behavior dominates the strength and service life of thermoelectric ***,a theoretical model of a thermoelectric film bonded to a graded substrate is *** interfacial shear stress,the normal stress in the thermoelectric film,and the stress intensity factors affected by various material and geometric parameters are comprehensively *** is found that adjusting the inhomogeneity parameter of the graded substrate,thermal conductivity,and current density of the thermoelectric film can reduce the risk of interfacial failure of the thermoelectric film/graded substrate *** a stiffer and thicker thermoelectric film is advantageous to the reliability of the thermoelectric film/graded substrate *** results should be of great guiding significance for the present and upcoming applications of thermoelectric materials in various fields.

关键词： thermoelectric film graded substrate interfacial behavior singular integral equation shear stress intensity factor

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低速冲击下裂纹成核的位错模型

南京航空航天大学学报 2012年第5期44卷 657-662页

作者：黄再兴南京航空航天大学机械结构力学及控制国家重点实验室南京210016

从理论上研究低速冲击下金属材料中微裂纹的成核,建立了裂纹成核的位错模型,并在其中考虑温度与晶粒尺寸的影响;给出了在低速冲击载荷作用下脆性裂纹成核与延性裂纹成核的速度判据;定义了体现材料抗低速冲击能力的速度阻抗,确立了脆性... 详细信息

从理论上研究低速冲击下金属材料中微裂纹的成核,建立了裂纹成核的位错模型,并在其中考虑温度与晶粒尺寸的影响;给出了在低速冲击载荷作用下脆性裂纹成核与延性裂纹成核的速度判据;定义了体现材料抗低速冲击能力的速度阻抗,确立了脆性裂纹成核与延性裂纹成核的速度阻抗的计算表达式;分析了在裂纹成核过程中的尺寸效应和脆性-延性转变。结果表明,裂纹成核的速度阻抗都随着晶粒的粗化而减小;脆性裂纹成核的速度阻抗随温度增加而增加,而延性裂纹成核的速度阻抗随温度增加而减小,两者的交点确定了脆性-延性转变温度。

关键词：微裂纹成核低速冲击速度阻抗尺寸效应韧脆转变