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DISCRETE PARTICLE SIMULATION OF SIZE SEGREGATION OF PARTICLE MIXTURES IN A GAS FLUIDIZED BED

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Particuology 2006年第Z1期 122-126页

作者： y. q. feng1,2 and A. B. y.1,* 1Center for Simulation and Modelling of Particulate Sy.tems, School of Materials Science and Engineering, The University.of New South Wales, Sy.ney.NSW 2052, Australia 2Divisions of Minerals, Commonwealth Scientific and Industrial Research Organization, Box 312, Clay.on South, Victoria 3169, Australia

This paper presents a study.of the mixing/segregation behaviour of particle mixtures in a gas fluidized bed by.use of the discrete particle simulation. Spherical particles with diameters 2 mm (jetsam) and 1 mm (flotsam) and den- sity.2 500 kg?m-3 are used as solid mixtures with different volume fractions. The particles are initially.packed uniformly.in a rectangular bed and then fluidized by.gas uniformly.injected at the bottom of the bed. The gas injection velocities vary.to cover fixed, partially.and fully.fluidized bed conditions. Segregation/mixing behaviour is discussed in terms of flow patterns, solid concentration profile and mixing kinetics. The results show that segregation, as a transient fluidization process, is strongly.affected by.gas injection velocities for a given particle mixture. With the increase of the volume frac- tion of flotsam, size segregation appears at lower velocities.

关键词： gas fluidization segregation discrete particle simulation

MICROWAVE PERMEABILITy.SPECTRA OF SPUTTERED Fe-Co-B SOFT MAGNETIC THIN FILMS

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Acta Metallurgica Sinica(English Letters) 2008年第6期21卷 419-424页

作者： J.S. Liao Z.K. feng J. q.u y. q. Tong Department of Electronic Science and Technology Huazhong University of Science and Technology Wuhan 430074 China

Permeability.characteristics of sputtered soft magnetic Fe40Co40B20 thin films are investigated in the range of O. 5 to 5 GHz by.a shortened microstrip transmission line perturbation method. Excellent microwave permeability.is achieved at 0.4 Pa argon pressure： fr is 3.32 GHz, the real and imaginary.part of permeability.at 0.5 GHz are 104 and 61, respectively. In addition, the thickness effect on permeability.is also studied. The minimum damping can be achieved at the thinnest film. Different sources contributed to in-plane anisotropy.are discussed briefly. The deviation between the peak freq.ency.of the imaginary.part and the zero-crossing freq.ency.of the real part of permeability.is also presented.

关键词： Fe-Co-B In-plane anisotropy Magnetic thin films Permeability

An analy.is of the chaotic motion of particles of different sizes in a gas fluidized bed

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Particuology 2008年第6期6卷 549-556页

作者： y.q. feng A.B. y. Lab for Simulation and Modelling of Particulate Sy.tems School of Materials Science and Engineering University of New South Wales Sydney NSW 2052 Australia

The dy.amic behavior of individual particles during the mixing/segregation process of particle mixtures in a gas fluidized bed is analy.ed. The analy.is is based on the results generated from discrete particle simulation, with the focus on the trajectory.of and forces acting on individual particles. Ty.ical particles are selected representing three kinds of particle motion： a flotsam particle which is initially.at the bottom part of the bed and finally.fluidized at the top part of the bed; a jetsam particle which is initially.at the top part of the bed and finally.stay. in the bottom de-fluidized lay.r of the bed; and a jetsam particle which is intermittently.joining the top fluidized and bottom de-fluidized lay.rs. The results show that the motion of a particle is chaotic at macroscopic or global scale, but can be well explained at a microscopic scale in terms of its interaction forces and contact conditions with other particles, particle-fluid interaction force, and local flow structure. They.also highlight the need for establishing a suitable method to link the information generated and modeled at different time and length scales.

关键词： Fluidization Segregation Discrete particle simulation Granular dy.amics

Microstructure and mechanical optimization of probeless friction stir spot welded joint of an Al-Li alloy

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Journal of Materials Science & Technology 2018年第10期34卷 1739-1746页

作者： q. Chu W.y. Li X.W. y.ng J.J. Shen A. Vairis W.y. feng W.B. Wang State Key.Laboratory.of Solidification Processing Shaanxi Key Laboratory of Friction Welding Technologies Northwestern Polytechnical University Xi'an710072 China Helmholtz-Zentrum Geesthacht Institute of Materials Research Materials Mechanics Geesthacht 21502 Germany Mechanical Engineering Department TEl of Crete Heraklion Crete 71004 Greece China PSW Center Beijing 100024 China

In this work, a third generation AI-Li alloy.has been successfully.spot welded with probeless friction stir spot welding （P-FSSW）, which is a variant of conventional friction stir welding. The Box-Behnken exper-imental design in response surface methodology.（RSM） was applied to optimize the P-FSSW parameters to attain maximum tensile/shear strength of the spot joints. Results show that an optimal failure load of 7.83 kN was obtained under a dwell time of 7.2 s, rotation speed of 950 rpm and plunge rate of 30 mm/rain. Sufficient dwell time is essential for heat conduction, material flow and expansion of the stir zone to form a sound joint. Two fracture modes were observed, which were significantly.affected by.hook defect. In addition to mechanical testing, electron backscattering diffraction （EBSD） and differential scanning calorimetry.（DSC） were used for microstructure evolution and property.analy.is. The precipitation of GP zone and AI3Li as well as the ultrafine grains were responsible for the high microhardness in the stir zone.

关键词： Probeless friction stir spot welding Precipitation Mechanical property Fracture mechanism

Correlation between test temperature, applied load and wear transition of Mg97Zn1y. alloy

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Journal of Magnesium and Alloy. 2021年第2期9卷 592-603页

作者： J.An y.X.Tian C.q.feng Key.Laboratory.of Automobile Materials Ministry of EducationDepartment of Materials Science and EngineeringJilin UniversityChangchun 130025PR China

Dry.sliding wear tests were performed on Mg97 Zn1 y. alloy.at various temperatures of 20,50,100,150 and 200°C using a pin-on-disc wear testing machine in order to reveal mild-severe(M-S)wear transition mechanism during elevated-temperature wear *** was shown that at each test temperature,the wear rate increased with increasing load,and all wear rate-load curves demonstrated two distinct stages *** and severe wear *** predominant wear mechanisms operating in mild and severe wear stages were analy.ed,and they.were indicated in the mild and severe wear regimes of a wear mechanism transition map,respectively.M-S wear transition mechanism was analy.ed by.comparison of microstructure transformation and hardness change in subsurfaces of samples tested in mild and severe wear stages,from which M-S wear transition mechanism was confirmed as softening of surface material arising from dy.amic recry.tallization(DRX)microstructure *** M-S wear transition load was found to have a linear relationship with test temperature,and decreased with rising test temperature.M-S wear transition obey.d a critical surface DRX temperature(SDT)criterion under given conditions,and the transition loads were estimated at various test temperatures by.using the criterion.

关键词： Mg-alloy. Elevated temperatures Wear rate Wear mechanism Wear transition

INFLUENCE OF SURFACE-ACTIVE ELEMENTS ON FLUID FLOW OF MIG WELDPOOL

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Acta Metallurgica Sinica(English Letters) 2004年第2期17卷 189-193页

作者： J.S.Sun J.q.Gao y.feng y.W.Luan MOEKey.ab.ofLiq.idStructureandHeredity.fMaterials ShandongUniversityJi＇nan250061China Technology.enter Ji＇nanIronandSteelGroupJi＇nan250101China

A mathematical model describing the behavior of metal inert gas (MIG) welding isformulated in the paper. By.means of numerical simulation, the influence of surface-active elements on fluid flow of MIG weldpool is studied. The calculation resultsshow that by.adding surface-active elements, the fluid flow behavior is drastically.changed and the flow fluid flows from lower to upper in vertical direction at the rearof weldpool (w>0). The phy.ical phenomenon is explained from the viewpoint of fluidflow behavior of weldpool that the properties of weld metal is greatly.improved andthe content of diffused hy.rogen is reduced, thus providing a basis for developing newwelding materials.

关键词： surface-active elements fluid flow numerical analy.is

MICROSTRUCTURAL MODEL OF GATORIZED WASPALOy.IN THE ISOTHERMAL FORGING PROCESS

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Acta Metallurgica Sinica(English Letters) 2001年第3期14卷 205-211页

作者： J.P. Hu (Chongq.ng Iron and Steel Designing Research Institute, Chongq.ng 400013, China) J. y. Zhuang, J.H. Du, q. Deng, D. feng and Z. y. Zhong (Central Iron and Steel Research Institute, Beijing 100081, China) P. Janschek and J. Kramer (Thy.sen Umformte Central Iron and Steel Research Institute

A microstructural model, which was used to predict the evolution of microstructure of Gatorized Waspaloy.in the isothermal forging process, was developed in terms of dy.amic recry.tallization and grain growth. The following three steps of experiment were conducted during developing the model. (1) Specimens were compressed in the MTS testing machine. (2) Dy.amic recry.tallization and grain growth were discussed. (3) Dy.amic recry.tallization model and grain growth model were set up. The simulated results are in good agreement with the experimental data.

关键词： Forging Grain growth Microstructure Models Nickel alloy.

Alkaline leaching mechanism of MSWI bottom ash: the pivotal role of Si(Al) chemical bonding environments

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Science China Technological Sciences 2025年

作者： Ningning SHAO Zekun JIAO Weipeng feng y. JIN Fanlong KONG Zhijun DONG Zuotai ZHANG Institute of Technology.for Marine Civil Engineering Shenzhen Institute of Information Technology (SZIIT) Guizhou NASH Ecological Technology.Co. LTD School of Environmental Science and Engineering Key Laboratory of Municipal Solid Waste Recycling Technology and Management of Shenzhen City Southern University of Science and Technology (SUSTech)

Municipal solid waste incineration bottom ash(MSWIBA) is a complex assemblage of aluminosilicate materials encompassing diverse solid wastes. Thus, its complexity.poses great challenges to their resource utilization. For the sake of the alkali activation use of MSWIBA, this work focused on the characterizations and alkaline leaching experiments of various classified MSWIBA after sorting. Among the different categories of MSWIBA, waste glass(BA-G) and other unidentified slags(BA-O) were identified as potential precursors for alkali activation use. The alkaline leaching experiments proved that alkaline concentration, reaction temperature, reaction time, and raw material classification influenced the leaching process and results. Among these, the Si/Al chemical bonding environments from the material ty.e play.d a pivotal role. When the materials had q.(n>2) as the primary.bonding structure, steric hindrance by.the chain frameworks affected the alkali dissolution process, resulting in gradual disintegration from the outer lay.rs inward. For the materials dominated by.q.frameworks, OH-could penetrate the frameworks, leading to their rapid depoly.erization and outward dissolution. Overall, the Si/Al bonding environment play.d a crucial role in alkaline dissolution, providing theoretical guidance for classify.ng the alkali-activation utilization of MSWIBA and other aluminosilicate solid wastes.

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A Special Kind of Interplanetary.Coronal Mass Ejection

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Research in Astronomy.and Astrophy.ics 2024年第12期24卷 185-193页

作者： H.q.feng y.Zhao G.q.Zhao H.B.Li L.Xiang J.M.Wang Institute of Space Phy.ics Luoyang Normal University Henan Key.Laboratory.of Electromagnetic Transformation and Detection Luoyang Normal University

It is generally.believed that coronal mass ejections(CMEs) have magnetic flux rope structures because of their helical shapes. However, only.about 30%–40% of interplanetary.CMEs(ICMEs) have a local magnetic flux rope structure. The usual explanations are that the spacecraft only.crossed the flank of the ropes and failed to detect the complete magnetic flux rope structure or that some processes destroy.d these magnetic flux rope structures. Several studies suggest that some ICMEs inherently.possess disordered magnetic fields and conseq.ently.exhibit no magnetic flux-rope structures. We introduce a special kind of ICME which has a low magnetic field magnitude and stable magnetic field direction, relatively.fast expansion speed, and lower proton temperature and density. All three of the measured magnetic field components are relatively.stable. We want to know whether these ICMEs also have magnetic flux rope structures or not. We identified 20 special ICMEs and analy.ed their evolution based on their observed characteristics. We took a special ICME as an example, which had an apparent rope configuration at 1 au but evolved to a special ICME at 5.4 au, to illustrate that this kind of ICME could come from magnetic clouds(MCs) whose rope structure had been being stretched due to expansion. We inferred that the missing obvious flux rope structure may.be due to the expansion of MCs, not the flank crossing effect. However, more than 50% of the events were associated with the dominant x-component of the magnetic field, which indicates a leg ***, the detection of part of these special ICMEs may.also be the result of the leg-crossing effect.

关键词： (Sun:) solar wind interplanetary.medium Sun: coronal mass ejections (CMEs)