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Existence of Multiple solutions for semilinear elliptic equations in the annulus

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Applied Mathematics(A Journal of Chinese Universities) 2009年第3期24卷 263-268页

作者： mao An-min MO Xiu-ming School of Mathematical Sciences Qufu Normal University Qufu 273165 China Department of Biotechnology Beijing City University Beijing 100094 China

The existence of radial solutions of Δu ＋ λg（｜x｜）f（u） = 0 in annuli with Dirichlet（Dirichlet/Neumann） boundary conditions is *** is proved that the problems have at least two positive radial solutions on an... 详细信息

关键词： fixed point index Dirichlet problems annulus

Exergy Analysis and Optimization of Ladle Furnace Refining Process

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Journal of Iron and Steel Research International 2010年第11期17卷 24-28页

作者： min Yi JIANG mao-fa School ofMaterials and Metallurgy Northeastern University Shenyang 110819 Liaoning China

To decrease energy consumption of ladle furnace, exergy analysis and optimization were conducted based on the ladle furnace refining process of modern clean steelmaking. Exergy analysis results showed that exergy loss induced by unavailable electric energy is the largest, and the electric energy efficiency is 46.20%. To cut down the unavailable electric energy, industrial experiments of submerged arc heating were carried out combined with slag composition modification. Results showed that submerged arc heating can be achieved within most heating period, average heating rate increased by 0. 5 ℃/min, unavailable electric energy decreased by 21. 730 MJ per ton steel, and electric energy efficiency was enhanced by 14.84 %. As the refining cycle was shortened, the exergy loss induced by heat elimination decreased from 19. 455 MJ per ton steel to 11. 066 MJ per ton steel.

关键词： LF exergy analysis exergy loss submerged arc heating

Preparation of semisolid AlSi7Mg alloy slurry through weak traveling-wave electromagnetic stirring

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International Journal of minerals,Metallurgy and Materials 2009年第5期16卷 554-558页

作者： Zhen-duo Zhao Wei-min mao Sha Li Rong-mao Zhong School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China

The semisolid AlSi7Mg alloy slurry with large capacity was prepared by low superheat pouring and week traveling-wave electromagnetic stirring. The effects of electromagnetic stirring power and frequency on the shape and distribution of primary α-A1 grains in the AlSi7Mg alloy slurry were discussed. The experimental results show that the AlSi7Mg alloy slurry with fine and spherical primary α-A1 grains distributed homogeneously can be obtained. Under the condition of low superheat pouring and week traveling-wave electromagnetic stirring, when the pouring temperature is 630℃, raising the stirring power or frequency appropriately can gain a better shape of primary α-Al grains; but if the stirring power or frequency is increased to a certain value （1.72 kW or10 Hz）, the shape of primary α-A1 grains cannot be obviously improved and spherical primary α-Al grains distributed homogeneously can be still obtained.

关键词： semisolid AlSi7Mg alloy slurry electromagnetic stirring primary a-A1

Behaviors of different inhibitors during secondary recrystallization of a grain-orientated silicon steel

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International Journal of minerals,Metallurgy and Materials 2011年第3期18卷 314-319页

作者： Feng-e Cui Ping Yang Wei-min mao School of Materials Science and Engineering University of Science and Technology Beijing 100083 China

The behaviors of different inhibitors including their composition, size, distribution, coalescence and coarsening were experimen-tally studied. It was observed that during secondary recrystallization of the tested steel, the key inhibition effect was produced by Cu2S and AlN, but not MnS. With the increase of temperature, the size distributions of AlN and Cu2S were changed to some extent. However, signifi-cant changes in particle size were not observed. The initial temperature of abnormal growth was determined by measuring the evolution of particle sizes and their distribution density during heat treatment. AlN and Cu2S are the dominant inhibitors and both are necessary, which is verified by calculating the Zener factor.

关键词： silicon steel secondary recrystallization inhibitors grain growth

Effect of Initial Goss Texture Sharpness on Texture Evolution and Magnetic Properties of Ultra-thin Grain-oriented Electrical Steel

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Acta Metallurgica Sinica(English Letters) 2017年第9期30卷 895-906页

作者： Rui-Yang Liang Ping Yang Wei-min mao School of Materials Science and Engineering University ofScience and Technology BeijingBeijing 100083China

In this study, high- and low-grade grain-oriented electrical steels were used as the initial materials to produce 0.08-mm-thick sheet with one-step cold-rolling method. Electron backscattering diffraction analysis technique and X-ray diffraction texture analysis technique were adopted to investigate the effect of initial Goss texture sharpness on texture evolution and magnetic properties of ultra-thin grain-oriented electrical steel. The results showed that primary recrystal- lization and secondary recrystallization were the main processes that occurred during annealing. The induced factors for secondary recrystallization of two grades samples were not Consistent. The high-grade samples presented texture induction mechanism, while the low-grade samples revealed strong surface-energy induction mechanism. The initial Goss texture sharpness had a great impact on texture evolution and magnetic properties of ultra-thin grain-oriented electrical steel. The Goss texture component formed after primary recrystallization was stronger, and better magnetic properties were obtained at low frequencies. For low-grade samples, secondary recrystallization enhanced the intensity of Goss texture, and both grain size and texture contributed to better high-frequency magnetic properties after secondary recrystallization. By controlling the annealing process, the magnetic properties of low-grade products could be significantly improved, thus achieving conversion from low-grade to high-grade products.

关键词： Ultra-thin grain-oriented electrical steel Goss texture Secondary recrystallization Magnetic properties

Effect of heat treatment on the microstructure and micromechanical properties of the rapidly solidified Mg61.7Zn34Gd4.3 alloy containing icosahedral phase

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International Journal of minerals,Metallurgy and Materials 2019年第7期26卷 869-877页

作者： Wen-bo Luo Zhi-yong Xue Wei-min mao School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China Institute for Advanced Materials North China Electric Power University Beijing 102206 China School of Energy Power and Mechanical Engineering North China Electric Power University Beijing 102206 China

In this paper, the microstructure evolution of the rapidly solidified (RS) Mg61.7Zn34Gd4.3 (at%, atomic ratio) alloy at high temperatures was investigated. The hardness and elastic modulus of the main precipitated phases were also analyzed and compared with those of the α-Mg matrix on the basis of nanoindentation tests. The results show that the RS alloy consists of either a petal-like icosahedral quasicrystal (IQC) phase (~20 μm) and block-shaped H1 phase (~15 μm) or IQC particles with an average grain size of ~107 nm as well as a small proportion of amorphous phase, which mainly depends on the holding time at the liquid temperature and the thickness of the ribbons. The IQC phase gradually transforms at 400?C to a short-rod-shaped μ-phase (Mg28.6Zn63.8Gd7.7) with a hexagonal structure. The hardness of the IQC phase is higher than that of H1 phase, and both phases exhibit a higher hardness than the α-Mg matrix and the μ-phase. The elasticity of the H1 phase is superior to that of the α-Mg matrix. The IQC phase possesses a higher elastic modulus than H1 phase. The easily formed H1 phase exhibits the poorest plastic deformation capacity among these phases but a higher elastic modulus than the α-Mg matrix.

关键词： magnesium alloy icosahedral phase rapidly solidification nanoindentation micromechanical properties

Semisolid A356 alloy feedstock poured through a serpentine channel

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International Journal of minerals,Metallurgy and Materials 2009年第5期16卷 603-607页

作者： Xiao-rong Yang Wei-min mao Chong Gao School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China School of Materials Science and Engineering Taiyuan University of Science and Technology Taiyuan 030024 China

Fine spheroidal and equiaxed nondendritic microstructures required for semisolid casting can be formed through a serpentine pouting channel. Effects of the pouring temperature and the vertical section length of the serpentine pouring channel were studied. The results indicate that both favorable semisolid microstructures of A356 aluminum alloy can be generated by a serpentine pouring channel, and the solid shell inside the channel can be avoided when the pouting temperature is in the range from 660 to 680℃. It is also shown that the vertical section length of the serpentine pouting channel has a significant influence on the microstructure of the feedstock, namely both the microstructure of the feedstock and the microstructure uniformity in the radial direction get worse when the vertical section length is shortened; moreover, the pouring temperature for obtaining the feedstock with suitable microstructure decreases. The relevant mechanisms were discussed.

关键词： semisolid microstructure serpentine channel primary α-A1

Preparation of semi-solid aluminum alloy slurry poured through a water-cooled serpentine channel

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International Journal of minerals,Metallurgy and Materials 2012年第1期19卷 48-53页

作者： Zheng-zhou Chen Wei-min mao Zong-chuang Wu School of Materials Science and Engineering University of Science and Technology BeijingBeijing 100083China

A water-cooled serpentine channel pouring process was invented to produce semi-solid A356 aluminum alloy slurry for rheocast ing, and the effects of pouring temperature and circulating cooling water flux on the microstmcture of the slurry were investigated. The results show that at the pouring temperature of 640-680~C and the circulating cooling water flux of 0.9 m3/h, the semi-solid A356 aluminum alloy slurry with spherical primary a（A1） grains can be obtained, whose shape factors are between 0.78 and 0.86 and the grain diameter can reach 48-68 ~am. When the pouring temperatures are at 660-680~C, only a very thin solidified shell remains inside the serpentine channel and can be removed easily. When the serpentine channel is cooled with circulating water, the microstructure of the semi-solid slurry can be improved, and the serpentine channel is quickly cooled to room temperature after the completion of one pouring. In terms of the productivity of the special equipment, the water-cooled serpentine channel is economical and efficient.

关键词： semi-solid slurry aluminum alloys microstructure rheocasting

Solutions for Schrodinger-Poisson system involving nonlocal term and critical exponent

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Applied Mathematics(A Journal of Chinese Universities) 2023年第3期38卷 357-372页

作者： MO Xiu-ming mao An-min WANG Xiang-xiang School of Biomedicine Beijing City UniversityBeijing 100094China School of Mathematical Sciences Qufu Normal UniversityQufu 273165China.

In this paper,we consider the following Kirchhoff-Schrodinger-Poisson system:{−(a+b∫_(R^(3))|∇u|^(2))△u+u+ϕu=μQ(x)|u|^(q-2)u+K(x)|u|^(4)u,in R^(3),−△ϕ=u^(2) the nonlinear growth of|u|^(4)u reaches the Sobolev critical *** combining the variational method with the concentration-compactness principle of Lions,we establish the existence of a positive solution and a positive radial solution to this problem under some suitable *** nonlinear term includes the nonlinearity f(u)~|u|^(q-2)u for the well-studied case q∈[4,6),and the less-studied case q∈(2,3),we adopt two different strategies to handle these *** result improves and extends some related works in the literature.

关键词： variational methods critical exponent concentration-compactness principle