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flux mechanism of compound flux on ash and slag of coal with high ash melting temperature

Chinese Journal of Chemical Engineering 2019年第5期27卷 1200-1206页

作者： Chengli Wu Beibei Wang Jiuqiang Zheng Hanxu Li School of Chemical Engineering Anhui University of Science and Technology

The melting temperature of Z coal ash was reduced by adding calcium–magnesium compound flux(WCaO/WMgO=1). In the process of simulated coal gasification, the coal ash and slag were prepared. The transformation of minerals in coal ash and slag upon the change of temperature was studied by using X-ray diffraction(XRD). With the increase of temperatures, forsterite in the ash disappears, while the diffraction peak strength of magnesium spinel increases,and the content of the calcium feldspar increases, then the content of the amorphous phase in the ash increases obviously. The species and evolution process of oxygen, silicon, aluminum, calcium, magnesium at different temperatures were analyzed by X-ray photoelectron spectroscopy(XPS). The decrease of the ash melting point mainly affects the structural changes of silicon, aluminum and oxygen. The coordination of aluminum and oxygen in the aluminum element structure, e.g., tetracoordinated aluminum oxide, was changed. Tetrahedral [AlO4] and hexacoordinated aluminoxy octahedral [AlO6] change with the temperature changing. The addition of Ca2+ and Mg2+ destroys silica chain, making bridge oxide silicon change into non-bridge oxysilicon;and bridge oxygen bond was broken and non-bridge oxygen bond was produced in the oxygen element structure. The addition of calcium and magnesium compound flux reacts with aluminum oxide tetrahedron, aluminum oxide octahedron and silicon tetrahedron to promote the breakage of the bridge oxygen bond. Ca2+ and Mg2+ are easily combined with silicon oxide and aluminum oxide tetrahedron and aluminum. Oxygen octahedrons combine with non-oxygen bonds to generate low-melting temperature feldspars and magnesite minerals, thereby reducing the coal ash melting temperatures. The structure of kaolinite and mullite was simulated by quantum chemistry calculation, and kaolinite molecule has a stable structure.

关键词： Coal ash and slag Compound flux X-ray photoelectron spectroscopy Transformation of mineral structure Structure of kaolinite and mullite

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CFD model simulation of bubble surface area flux in flotation column reactor in presence of minerals

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International Journal of Mining Science and Technology 2018年第6期28卷 999-1007页

作者： A.R.Sarhan J.Naser G.Brooks Department of Mechanical and Product Design Engineering Swinburne University of TechnologyHawthornVictoria 3122Australia Department of Mechanical Engineering University of Anbar RamadiAnbar 31001Iraq

Bubble surface area flux(S_b) is one of the main design parameter in flotation column that typically employed to describe the gas dispersion properties, and it has a strong correlation with the flotation rate constant. There is a limited information available in the literature regarding the effect of particle type,density, wettability and concentration on Sb. In this paper, computational fluid dynamics(CFD) simulations are performed to study the gas–liquid–solid three-phase flow dynamics in flotation column by employing the Eulerian–Eulerian formulation with k-e turbulence model. The model is developed by writing Fortran subroutine and incorporating then into the commercial CFD code AVL FIRE, *** paper studies the effects of superficial gas velocities and particle type, density, wettability and concentration on Sband bubble concentration in the flotation column. The model has been validated against published experimental data. It was found that the CFD model was able to predict, where the response variable as indicated by R-Square value of 0.98. These results suggest that the developed CFD model is reasonable to describe the flotation column reactor. From the CFD results, it is also found that Sb decreased with increasing solid concentration and hydrophobicity, but increased with increasing superficial gas velocity. For example, approximately 28% reduction in the surface area flux is observed when coal concentration is increased from 0 to 10%, by volume. While for the same solid concentration and gas flow rate, the bubble surface area flux is approximately increased by 7% in the presences of sphalerite.A possible explanation for this might be that increasing solid concentration and hydrophobicity promotes the bubble coalescence rate leading to the increase in bubble size. Also, it was found that the bubble concentration would decrease with addition of hydrophobic particle(i.e., coal). For instance, under the same operating conditions, approximately 23% reduc

关键词： CFD Froth flotation Bubble surface area flux Solid properties Bubble concentration

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Comparison of feasibility,microstructure and performance of hybrid laser arc,activated flux tungsten inert gas and friction stir welding for thick plate of innovative ultra-pure ferritic stainless steel

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Journal of Iron and Steel Research International 2022年第4期29卷 665-676页

作者： Jian Han Lian-meng Liu Xin-ya Chen Min-fang Chen Lei Cui Yang-chuan Cai Yin-bao Tian School of Materials Science and Engineering Tianjin University of TechnologyTianjin 300384China School of Materials Science and Engineering Tianjin UniversityTianjin 300072China

An innovative grade of ferritic stainless steel,ultra-pure 18Cr–2Mo thick plate,was designed and produced for special industrial *** order to maintain its mechanical properties after joining,three advanced joining methods,hybrid laser arc welding,activated flux tungsten inert gas welding and friction stir welding,were selected and conducted to connect the thick *** feasibility of three joining methods,the microstructure and mechanical properties were compared,and the results have demonstrated that the sound joint was successfully produced using the selected parameters through friction stir *** obtained hardness and impact toughness of the weld zone were *** terms of activated flux tungsten inert gas welding,the crack will be created due to microstructural *** as for hybrid laser arc welding,the weld zone is narrow,and the addition of wire during welding for the top weld metal area leads to higher formation ratio of low-angle grain boundaries,which is beneficial to performance of the ***,there is still a weak area in the fusion line of the welded *** result has illustrated that the welding of innovative ultra-pure ferritic stainless steel thick plate by friction stir welding is feasible.

关键词： Ultra-pure ferritic stainless steel Hybrid welding Activated flux tungsten inert gas Friction stir welding Microstructural evolution Mechanical property

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Characteristics and influence factors of NO2 exchange flux between the atmosphere and P. nigra

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Journal of Environmental Sciences 2019年第10期31卷 155-165页

作者： Chun Chen Yuzheng Wang Yuanyuan Zhang Chengtang Liu Xiaoxiu Lun Yujing Mu Chenglong Zhang Junfeng Liu Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China University of Chinese Academy of Sciences Beijing 100049 China Center for Excellence in Urban Atmospheric Environment Institute of Urban Environment Chinese Academy of Sciences Xiamen 361021China College of Environmental Science & Engineering Beijing Forest University Beijing 100083 China

Nitrogen dioxide(NO2)is an important substance in atmospheric photochemical processes and can also be absorbed by plants.N02 fluxes between the atmosphere and *** seedlings were investigated by a double dynamic chambers method in Beijing from June 15to September 3,*** range of N02 exchange fluxes between *** seedlings and the atmosphere was from-14.6 to 0.8 nmol/(***)(the positive data represent N02 emissior from trees,while the negative values indicate absorption).Under ambient concentrations the mean NO2 flux during the fast-growing stage(Jun.15-Aug.4)was-3.0 nmol/(m2·sec)greater than the flux of-1.5 nmol/(m2-sec)during the later growth stage(Aug.8-Sept.3)The daily exchange fluxes of NO2 obviously *** fluxes were largest in the morning and decreased gradually over ***,the N02 fluxes were larger undei high light intensities than under low light intensities during the whole growth *** effects of temperature on N02 fluxes were different under two growth *** NO2exchange fluxes were larger in a range of temperatures close to 44℃in the fast-growing stage,whereas there were no evident differences in N02 exchange fluxes under widel differing temperatures in the later growth *** polluted conditions,the uptake ability of N02 was ***,the compensation point of N02 was 5.6 ppb ir the fast-growing stage,whereas it was 1.4 ppb in the later growth *** depositior velocities of NO2 were between 0.3 and 2.4 mm/sec.

关键词： Nitrogen dioxide Exchange flux P.nigra Compensation point

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Design of a PCB stator coreless axial flux permanent magnet synchronous motor based on a novel topology Halbach array

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Frontiers of Information Technology & Electronic Engineering 2019年第3期20卷 414-424页

作者： Xiao-yuan WANG Xiang LI Chun-peng LI Si-jia XU Le-tao LING College of Electrical Engineering and Automation Tianjin University

A novel topology Halbach permanent magnet array is proposed and applied to the design of a printed circuit board(PCB) axial flux permanent magnet(AFPM) motor. Compared with the traditional coreless AFPM motor, this novel topology for a Halbach permanent magnet array PCB stator AFPM motor has larger air-gap magnetic flux density and air-gap flux per pole. The magnetic flux leakage is effectively reduced, and the air-gap magnetic density is close to the sine wave. Results of the finite element analysis and prototype experiments verify the feasibility and effectiveness of the novel Halbach permanent magnet array PCB stator motor. A reference basis and practical value for the design of the PCB AFPM motor are provided.

关键词： Axial flux permanent magnet synchronous motor Printed circuit board Halbach permanent magnet array Finite element method

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Effect of SiO2 substitution with Al2O3 during high-Al TRIP steel casting on crystallization and structure of low-basicity CaO–SiO2-based mold flux

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Journal of Iron and Steel Research International 2020年第1期27卷 33-41页

作者： Ding-li Zheng Cheng-bin Shi Zhi-jun Li Jing Li Jung-wook Cho State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing 100083China Division of Steelmaking Shougang Qian’an Iron and Steel Co.Ltd.Qian’an 064404HebeiChina Graduate Institute of Ferrous Technology Pohang University of Science and TechnologyPohang 790-784Republic of Korea

The crystallization and structure of non-conventional lime-silica-based mold fluxes after undergoing slag-steel interaction in casting high-AI transformation induced plasticity(TRIP)steel were *** results showed that the crystallization temperatures of the mold fluxes decreased with decreasing the SiO2/Al2O3 ratio,and CaO/MnO2 ratio had an opposite effect on the crystallization *** crystalline phases precipitated in the mold flux were Ca4Si2O7F2 and *** SiO2/Al2O3 ratio and increasing CaO/MnO2 ratio in the mold fluxes have no influence on the types of crystalline *** dominant crystalline phase precipitated in each mold flux was Ca4Si2O7F2 with dendritic morphology,except for part of that with globular morphology in the mold flux without MnO2 ***4 crystals are distributed in the space among Ca4Si2O7F2 *** size of Ca4Si2O7F2 crystals in the slag with higher S1O2/AI2O3 ratio is smaller,which is attributed to the polymerization degree of the mold flux with increasing SiO2/Al2O3 ratio.[SiO4]-tetrahedral,[AlO4]-tetrahedral and T-O-T bending(T denotes Si or Al)depolymerized gradually with decreasing SiO2/Al2O3 ratio,and an opposite trend was observed for the case with increasing CaO/MnO2 *** polymerization degree of the mold fluxes decreased,which would result in the decrease in the viscosity of the mold fluxes.

关键词： Mold flux Crystallization Structure Continuous casting High-AI steel

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Numerical solutions of 2-D steady compressible natural convection using high-order flux reconstruction

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Acta Mechanica Sinica 2019年第2期35卷 401-410页

作者： Yaojie Yu Feng Liu Tingbo Zhou Chao Gao Ya Liu National Key Laboratory of Aerodynamic Design and Research Northwestern Polytechnical UniversityXi’an 710072 China Department of Mechanical and Aerospace Engineering University of California Irvine Irvine CA 92697 USA Facility Design and Instrumentation Institute China Aerodynamics Research and Development CenterMianyang 621000 China

Low Mach number flows are common and typical in industrial applications. When simulating these flows, performance of traditional compressible flow solvers can deteriorate in terms of both efficiency and accuracy. In this paper, a new high-order numerical method for two-dimensional(2-D)state low Mach number flows is proposed by combining flux reconstruction(FR)and preconditioning. Firstly, a Couette flow problem is used to assess the efficiency and accuracy of preconditioned FR. It is found that the FR scheme with preconditioning is much more efficient than the original FR scheme. Meanwhile,this improvement still preserves the numerical accuracy. Using this new method and without the Boussinesq assumption,classic natural convection is directly simulated for cases of small and large temperature differences. For the small temperature difference, a p and h refinement study is conducted to verify the grid convergence and accuracy. Then, the influence of the Rayleigh number (Ra) is analyzed. By comparing with the reference results, the numerical results of preconditioned FR is very close to that calculated by incompressible solvers. Furthermore, a large temperature difference test case is calculated and analyzed, indicating this method is not limited by the Boussinesq assumption and is also applicable to heat convection with large temperature differences.

关键词： flux reconstruction Preconditioning method Low Mach flows Natural convection

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Dynamics of a neuron exposed to integer-and fractional-order discontinuous external magnetic flux

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Frontiers of Information Technology & Electronic Engineering 2019年第4期20卷 584-590页

作者： Karthikeyan RAJAGOPAL Fahimeh NAZARIMEHR Anitha KARTHIKEYAN Ahmed ALSAEDI Tasawar HAYAT Viet-Thanh PHAM Center for Nonlinear Dynamics Defence University Institute of Energy Mekelle University Biomedical Engineering Department Amirkabir University of Technology NAAM Research Group Faculty of Science King Abdulaziz University Department of Mathematics Quaid-i-Azam University Modelling Evolutionary Algorithms Simulation and Artificial Intelligence Faculty of Electrical and Electronics Engineering Ton Duc Thang University

We propose a modified Fitzhugh-Nagumo neuron(MFNN) model. Based on this model, an integerorder MFNN system(case A) and a fractional-order MFNN system(case B) were investigated. In the presence of electromagnetic induction and radiation, memductance and induction can show a variety of distributions. Fractionalorder magnetic flux can then be considered. Indeed, a fractional-order setting can be acceptable for non-uniform diffusion. In the case of an MFNN system with integer-order discontinuous magnetic flux, the system has chaotic and non-chaotic attractors. Dynamical analysis of the system shows the birth and death of period doubling, which is a sign of antimonotonicity. Such a behavior has not been studied previously in the dynamics of neurons. In an MFNN system with fractional-order discontinuous magnetic flux, different attractors such as chaotic and periodic attractors can be observed. However, there is no sign of antimonotonicity.

关键词： Fitzhugh-Nagumo Chaos Fractional order Magnetic flux

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Study on Laminar Natural Convection Heat Transfer from a Hemisphere with Uniform Heat flux Surface

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Journal of Thermal Science 2019年第2期28卷 232-245页

作者： ZHANG Jian LIU Jie LU Wenqiang School of Engineering Science University of Chinese Academy of Sciences

By employing the modified model based on Bejan et al., laminar natural convection heat transfer from a hemisphere with uniform heat flux surface has been numerically investigated. Extensive results of two different surface boundary conditions are obtained for a wide range of Grashof numbers(10 ≤ Gr ≤ 10~7) and Prandlt number of 0.72. The characteristics of heat transfer and fluid flow are analyzed in terms of isotherm contours and streamline patterns, radial and tangential velocities, dimensionless temperature profiles, local friction and pressure drag coefficients, as well as local and average Nusselt numbers. Meanwhile, the effects of Grashof number and adiabatic surface on flow motion and heat transfer have been studied. No recirculation zone or flow separation generates over the top of the hemisphere compared to the isothermal sphere. Owing to the curvature effect, the maximum values of local friction and pressure drag coefficients appear at the corner point B. Comparisons with the previous results are also reported in detail. All the results are in good agreement with the numerical data. Moreover, both local and average Nusselt numbers show a positive dependence on Grashof number. The values of the non-adiabatic case are smaller than that of the adiabatic case due to the preheating effect. Finally, two precise and general correlations of average Nusselt number varying with Grashof numbers have been presented, which can provide an effective prediction for the heat transfer rate in engineering applications, and offer academic values for the future research.

关键词： numerical simulation natural convection hemisphere uniform heat flux heat transfer correlations

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Effectiveness of radiative heat flux in MHD flow of Jeffrey-nanofluid subject to Brownian and thermophoresis diffusions

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Journal of Hydrodynamics 2019年第2期31卷 421-427页

作者： Muhammad Ijaz Khan Tasawar Hayat Muhammad Waqas Ahmed Alsaedi Muhammad Imran Khan Department of Mathematics Quaid-I-Azam UniversityIslamabadPakistan Nonlinear Analysis and Applied Mathematics(NAAM)Research Group Department of MathematicsFaculty of ScienceKing Abdulaziz UniversityJeddahSaudi Arabia Heriot Watt University Edinburgh CampusEdinburghUK

Our interest here in this investigation is to explore the thermophoresis and Brownian motion characteristics in flow induced by stretched *** conducted Jeffrey material formulates the flow *** forms of stretching and free stream velocities are *** radiation and convective heating processes describe the phenomenon of heat *** controls of nanoparticles are considered on the *** compatible transformations produce the strong nonlinear differential *** problems are computed analytically utilizing *** nee domain is detennined and major results are concluded for different parameters *** transfer rate and drag force are also explained for various physical *** analysis reveals that heat transfer rate augments via larger radiation parameter and Biot *** larger Brownian motion and thermophoresis parameters have opposite characteristics on concentration field.

关键词： Jeffrey nanomaterial non-linear radiative heat flux convective boundary conditions.Brownian and thermophoresis diffusions

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