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Deduction and Validation of an Eulerian-Eulerian Model for Turbulent Dilute Two-Phase Flows by Means of the Phase Indicator Function-Disperse Elements Probability Density Function

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Chinese Journal of Chemical Engineering 2000年第3期8卷 189-202页

作者： Santiago Laín Ricardo Aliod mvt-ust Fachbereich Ingenieurwissenschaften Martin-Luther-UniversitatHalle-WittenbergD-06099Halle(Saale)GermanyFluid Mechanica DepartmentE.U.Politecnica de Huesca.University of ZaragozaCarretera Zaragoza km.6722071 HuescaSpain

A statistical formalism overcoming some conceptual and practical difficulties arising in existing two-phase flow (2PHF) mathematical modelling has been applied to propose a model for dilute 2PHF turbulent Hows. Phase interaction terms with a clear physical meaning enter the equations and the formalism provides some guidelines for the avoidance of closure assumptions or the rational approximation of these terms. Continuous phase averaged continuity, momentum, turbulent kinetic energy and turbulence dissipation rate equations have been rigorously and systematically obtained in a single step. These equations display a structure similar to that for single-phase flows. It is also assumed that dispersed phase dynamics is well described by a probability density function (pdf) equation and Eulerian continuity, momentum and fluctuating kinetic energy equations for the dispersed phase are deduced. An extension of the standard k-e turbulence model for the continuous phase is used. A gradient transport model is adopted for the dispersed phase fluctuating fluxes of momentum and kinetic energy at the non-colliding, large inertia limit. This model is then used to predict the behaviour of three axisymmetric turbulent jets of air laden with solid particles varying in size and concentration. Qualitative and quantitative numerical predictions compare reasonably well with the three different sets of experimental results, studying the influence of particle size, loading ratio and flow confinement velocity.

关键词： two-phase flow turbulence phase indicator function pdf ensemble average jet

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NO_x Formation from Several Chinese Coals during Combustion in Packed Bed

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International Journal of Minerals,Metallurgy and Materials 1998年第2期12卷 65-69页

作者： Shengli Wu Chunbao Xu Qiushuang Shou Daqiang Cang Metallurgy School, ust Beijing, Beijing 100083, China Metallurgy School UST Beijing Beijing 100083 China

The formation characteristics of NO_x during combustion of four typical Chinese coals have been studied in a packed bed combustor. The studies included the effects of chemical composition of coals and volatile matters, and combustion conditions, i.e. preheating temperatures of combustion gas, on conversion of NO_x during combustion. In term of the combustion experiments, there is a close relation between coal composition and conversions of NO_x. Coals with a higher nitrogen content give a lower F_(NO_x)~0, and coals with a higher volatile content give a lower F_(NO_x)~0. The further devolatilization experiments showed that volatile matters in the coal have an important effect on reducing conversion of coal-nitrogen to NO_x. It was interpreted as that the release of volatile matters during combustion caused a fuel-rich circumstance in the vicinity of coal particles which may restrain the formation of NO_x. Preheating temperatures of combustion gas has significant effects on conversions of NO_x and there exist a critical preheating temperature. At such temperature, lower F_(NO_x)~0 can be reached.

关键词： coal combustion packed bed NO_x formation

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Kinetics of Carbide Layer Forming on the Surface of Steel in Molten Systems

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International Journal of Minerals,Metallurgy and Materials 1998年第2期12卷 75-79页

作者： Shuhuan Wang Shengwen Wu Shantong Jin Metallurgy School, ust Beijing, Beijing 100083, China Metallurgy School UST Beijing Beijing 100083 China

A mathematical model of kinetics of carbide layer formed on the surface of steel in fused system was set up with the theory of non-stable diffusion mass transfer and regular solution sub-lattice. This model was analyzed and testified by the experiments in which the VC layers were formed on four kinds of steels as steel 45,4Cr5MoSiV1,T10, and Cr12MoV immersed in the V_2O_5-Na_2O-B_2O_5 fused system with the reducing agent of *** results showed that there was a good agreement between the model and the experimental results;the growth speed of carbide layer depended on the factors of carbon activity in substrate, treatment temperature,kinds of carbides and its structure etc.

关键词： fused systern carbide layer treatment kinetics

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Denitrogenization from Liquid Steel by Fluxes Treatment

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International Journal of Minerals,Metallurgy and Materials 1998年第2期12卷 80-83页

作者： Wenzhuo Guo Shantong Jin Xinhua Wang Jun Shu Metallurgy School, ust Beijing, Beijing 100083, China Metallurgy School UST Beijing Beijing 100083 China

By measuring the solubility of nitrogen in BaO-contained and TiO_2-contained fluxes at 1623K, the nitride capacity and nitrogen distribution ratio were calculated. Both fluxes had high nitride capacity and nitrogen distribution ratio. The results indicated that Both fluxes treatment were available for denitrogenizing steel. The kinetic studies about denitrogenization showed that nitrogen transfer in liquid steel is the controlled step of denitrogenization reaction, so to improve the mass transfer condition in liquid steel could accelerate the rate of denitrogenization. Under proper test conditions, it was proved to be possible to remove nitrogen over 70 percent from steel with TiO_2 contained fluxes.

关键词： denitrogenization flux nitfide capacity nitrogen distribution ratio

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Restraining NO_x Formation during Coal Combustion in Packed Bed

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International Journal of Minerals,Metallurgy and Materials 1998年第2期12卷 70-74页

作者： Shengli Wu Chunbao Xu Qiushuang Shou Daqiang Cang Metallurgy School, ust Beijing, Beijing 100083, China Metallurgy School UST Beijing Beijing 100083 China

The effects of various combustion conditions (i. e. particle size of coals, oxygen concentration in combustion gas and coal content in the fuel bed, etc.), on reducing conversion of NO_x during coal combustion were studied. Under the present combustion conditions, coals with smaller particle size gave the lower conversion of NO_x, and as expected that an decrease in overall stoichiometric ratio, whether by an decrease in O_2 content in combustion gas or by an increase in coal content in fuel bed would lead to a lower conversion of NO_x. In order to investigate the effect of metallic oxide layers on restraining NO_x formation, the combustion experiments for coal granules with adhering layer of various metallic oxides including Fe_2O_3, Ni_2O_3 and mixed oxides Fe-Ni-O_x were conducted in a packed bed combustor. The combustion experiments have shown that most of adhering materials gave considerable effect on reduction of NO_x emission during coal combustion.

关键词： coal combustion NO_x formation restraining metallic oxide

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Investigation on Coal-Oxygen Scrap Melting Process

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International Journal of Minerals,Metallurgy and Materials 1998年第2期12卷 61-64页

作者： Rong Xhu Yanhui Sun Yongquan Qiu Metallurgy School, ust Beijing, Beijing 100083, China Metallurgy School UST Beijing Beijing 100083 China

Investigation on the coal-oxygen scrap melting process shows that using internal-combustion coal-oxygen burner to melt scrap is feasible. Among four types of coal-oxygen furnaces-oxygen burner melting furnace is better than other types on the quotas of process. The metal yield is 95%～97%, the melt down carbon and sulphur contents are >1.0% and <0.080% respectively for this melting furnace. The coal-oxygen scrap melting process would have a significant effect on the technological transformation of EAF and BOF in China.

关键词： scrap melting coal-oxygen burner steelmaking

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Aluminum Control in CrNiMoV Steel during Electroslag Remelting Process

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International Journal of Minerals,Metallurgy and Materials 1998年第2期12卷 87-89页

作者： Anren Wang Yueguang Yu Jie Fu Metallurgy School, ust Beijing, Beijing 100083, China Metallurgy School UST Beijing Beijing 100083 China

The residual aluminum content has a great influence upon CrNiMoV steel properties and the optimal content is about 0.010%. The aluminum control during the ESR process has been investigated in this paper. All experiments were car ried out in a 20 kg ESR furnace. The results show that when a 60%CaF_2-30%Al_2O_3-5%SiO_2-5%CaO slag system and proper deoxidizing schedule is used, a reasonable ingot with optimal aluminum contents can be obtained. Silicon and magnesium contents are approximately the same with those in the electrode.

关键词： ESR aluminum CrNiMoV steel

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Economic-Mathematical Method to Determine the Optimum Production in Underground Coal Mine

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International Journal of Minerals,Metallurgy and Materials 1998年第2期12卷 57-60页

作者： Shaowen Zhang Xiangyi Li Zhongxui Li Guangcheng Wang Resources Engineering School, ust Beijing, Beijing 100083, China Resources Engineering School UST Beijing Beijing 100083 China

A method to determine optimum production is presented. First, based on analysis of various geological, technological and economic factors that influence the determination of underground mine capacity, a feasible range of production capacity is selected. Second, by means of scale economic theory and depletion feature of mineral resounce, an economicmathematical model that aimed at maximum net profit in the whole life of mine is developed to optimum production. The model was tested in a undergrond mine.

关键词： production of mine optimum economic-mathmatical model depletion

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Autonomous Path Planning For Robot Manipulators in Manufacturing Environment

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International Journal of Minerals,Metallurgy and Materials 1998年第2期12卷 104-107页

作者： Wei Wang Yang Yang Kui Yuan Information Engineering School, ust Beijing, Beijing 100083, China Information Engineering School UST Beijing Beijing 100083 China

A robot intelligent path planning system(RIPPS), which can be used as a robot off-line programming tool was introduced in this paper. C-space modeling and path search are key parts of the system. A fast C-space modeling is presented based on critical collision joint angle(CCJA), C-obstacle boundary can be computed by the feature points of obstacles. A modified A* algorithm is used for path search, although the path is slightly sub-optimal, a tremendous speed increase is achieved. RIPPS runs on a Silicon Graphic 4D/70 workstation, simulation results show that the system is efficient and practical for robot collision-free autonomous path planning in a structured and known environment.

关键词： robot path plalanning A~* algorithm

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AGC-ASC Synthetic Neural Net Control System in Rolling Process

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International Journal of Minerals,Metallurgy and Materials 1998年第2期12卷 108-112页

作者： Zhongsuo Shi Yuan Li Yikang Sun Information Engineering School, ust Beijing, Beijing 100083, China Information Engineering School UST Beijing Beijing 100083 China

Automation Gauge Control(AGC) and Automatic Shape Control(ASC) are coupling each other. The coupling models of AGC-ASC synthetic system for the thickness-crown have been established and two artificial neural networks controllers are given. The simulation of computer shows that the AGC-ASC synthetic system can obtain the expected thickness and shape precision with both schemes.

关键词： neural network neural net controller AGC-ASC synthetic system

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