Abstract: Through the process of grade and reserve calculation, a method of dealing with voxel for visualization technology and its applications in an integrated simulation system were provided for deposits. First, in order to construct regular volume data which can satisfy the needs, original sampling data were pretreated. Second, by the means of three interpolation methods, i.e. Thiessen polygon method, distance power inverse ratio method, Kriging method, users could choose an appropriate calculation method according to the fact of mines. Then, based on regular voxel information under different spatial interpolation methods, the grade and reserve were calculated in an appointed area of orebody.
Abstract: Rock's heat inflation is an irreversible process, and it is influenced by heating history. There is a great characteristic difference during heating and after cooling. Real-time tests on the thermal Iracture failure process of rock under uniaxial compressive and tension loading were carried out, the macro-mechanical properties of rock during thermal fracture failure were analyzed, and the thermal failure mechanism was discussed. According to the thermal fracture mechanism and its strength criterion, the maximum stress of samples was computed, and the results were in good agreement with the experimental.
Abstract: The model and method used to predict a composite foundation settlement process were studied. The characteristics of the modified Poisson model and its applicability were analyzed and a modified Poisson-superposition wavelet neural net model was proposed. Combined with practical observation data, the CFG pile composite foundation settlement process was analyzed and predicted. A comparison of the obtained theoretical results with those from the modified Poisson model was made. It is shown that the suggested model has better applicability and enables to predict with a higher accuracy, whose absolute error is less than 1mm.
Abstract: Gas-liquid-solid complex flow was complicated in the production of a condensate gas reservoir with wax deposition. Under experiment research results on the porous flow mechanism, the porous flow model was described to reveal the complex flow law. According to the phase change law for wax deposition and dew point line curves, and the change of the saturation of condensate gas with phase properties, gas-liquid-solid was transformed with phase change, which would result in the change of distribution of fluid pressure and influence or alter the characteristic and the process of condensate gas percolation flow. Under experimental results of wax deposition and phase change, the mechanical characteristics of fluids flowing through porous media and the relevant physicochemical problem were all summed up as solving the gas-liquid-solid coupling mathematical model. After considering the phase change action between condensate gas and condensate liquid, wax deposition interlarded with interracial drag force and capillary pressure engendered in the process of phase change. Numerical simulation results proved that the flow resistance increased and the production output decreased owing to wax deposition. The model could reveal the physical essence of porous flow.
Abstract: The microwave heating technique can avoid the non-homogeneous phenomenon of transferring heat and mass in pulverous ore materials by conventional heating. The temperature-rising characteristic of chromite ore fines containing coal in a microwave field was experimentally investigated with a microwave metallurgy oven. The results showed that chromite ore fines containing coal had a better temperature-rising characteristic in the microwave field of 2.45 GHz in frequency. Under the condition of the microwave power of 10 kW and the ore fines' mass of 1 kg, chromite ore fines containing coal reached 1 100℃ in 7 min with a temperature-rising rate of 157.1℃·min-1 whereas magnetite ore fines containing coal reached 1000℃ in 10 min with a tempera-ture-rising rate of only 100℃·min-1. Increasing the carbon-oxygen mole ratio can enhance the heating effect of chromite ore fines containing coal and reduce the effect of lime addition on the temperature-rising rate.
Abstract: To understand inclusions in tire cord steel, the solidification process has been analyzed and the conclusions drawn as follows. Al2O3 precipitates earlier during solidification and the growth rate depends on the diffusion of [A1] in molten steel; SiO2 begins to precipitate when the solidification fraction is 0.44, and the growth rate depends on the diffusion of [O]. The inclusion radius increases with the decrease of cooling rate, the radii of Al2O3 and Al2O3-SiO2 inclusions are 2.5 μm and 4.7 μm, respectively, after solidification as the cooling rate is 100 K·min-1. SiO2 content increases and Al2O3 content decreases during solidification.
Abstract: The principle of analyzing inclusions in steel by spectrum instrument was presented. The curve of Al2O3 pulse intensity by spectrum with its content by chemical analysis was established based on studying original Al2O3 pulse intensity from spectrum instrument, the relationship between the spectrum intensity and the inclusion size was determined, at last Al2O3 content and size distribution analysis on-line was realized. In comparison of chemical methods, the average error of the spectrum method is 3×10-6. The time of analyzing the inclusion content and size was shortened to 5 min from 2-5 d, which can offer a effective inclusion analysis technique for inclusion on-line control in steel-making and refinement processes.
Abstract: The factors which influence center segregation of continuously cast slabs were obtained through analyzing the database of sulphur print. It was indicated that center segregation became severer with the increasing contents of carbon, phosphorus and sulfur. Center segregation was reduced obviously if the content of manganese was higher than 1.5% and the ratio of manganese to sulfur was higher than 300. High degree of superheat, high pulling rate and increasing slab width increased the degree of center segregation. Since center segregation below Class B had little effect on the properties of steel, in order to low the ratio of center segregation of Class B-1.0 down to 10%, several control strategies were presented as follows. The contents of carbon, phosphorus and sulfur should be focalized in the lower range of steel grade demanded, but manganese upper operating range control. The referenced contents of the elements in molten steel are required as the following:[C]<0.07%,[P]<0.01%,[S]<0.005%,[Mn]>1.5%, and [Mn]/[S]>300. The degree of superheat is lower than 24℃ and the pulling rate is defined to 1.0-1.1 m·min-1. At the same time, a proper secondary cooling system of water distribution should be developed and the precision of continuous casters should be also improved.
Abstract: The microstructure evolution during multi-pass warm deformation at 550℃ and subsequent annealing process of lath martensite was investigated and compared with that of SPD (severe plastic deformation) cold-rolled lath martensite during annealing at 550℃. In comparison with tempered martensite at the same temperature, the effects of warm and cold deformation on ferrite grain size and cementite precipitation were discussed. The results showed that both warm and cold deformation significantly promoted the precipitation of cementite as well as recovery and recrystallization of ferrite. The grain size of recrystallized ferrite after warm deformation was 0.5μm, meanwhile rod-type cementite particles changed to spherical-type, the size of cementite grew along with the increase of deformation reduction. Then ferrite grains grew up to 1μm when subsequently annealed at 550℃ for 60 min, and Ostwald ripening occurred during annealing process. In cold-rolled specimens which annealed at 550℃for 30 min, 0.3-0.4μm ferrite grains and dispersed cementite particles with the size below 150 nm formed. The mean sizes of ferrite grains and cementite particles grew up to 1.9 μm and 160 nm during subsequent annealing.
Abstract: Dissolution of carbonitride in high-strength steel containing Ti and Nb was investigated by means of phase analysis and X-ray diffraction. The results show that the precipitation phases are fcc Ti(CN), (TiNb) (CN) and TiC when heated to 1250℃ without soaking; but mainly Ti(CN) and TiC when heated to 1250℃ and preserved for 45 min, their size increased from 300 nm to 323 nm, and the dissolution rates of Ti and Nb were 64.2% and 85.8% respectively. The content of precipitates extracted from the sample soaked for 80 min was almost the same with that for 45 min, whereas the particle size increased. It indicated that the dissolution process was apparently approaching thermodynamic equilibrium.
Abstract: The electrochemical properties of passivation film on 316L stainless steel were investigated by electrochemical impedance spectroscopy (EIS), Mott-Schottky analysis and cyclic voltammetry graph under the corresponding conditions. The result shows that passivation film on 316L stainless steel is steady in 60% acetic acid solution from 25℃ to 85℃, the polarization resistance decreased but the interface capacitance increased with increasing temperature. There is no obvious relation between temperature and semiconductor intrinsic properties. The passivation film represents the n-semiconductor characteristic in the potential interval of -0.5-0.1 V, the p-semiconductor characteristic in the potential interval of 0.1-0.9 V, and the n-semiconductor characteristic in the potential interval of 0.9-1.1 V. The graph of cyclic voltammetry shows that when the temperature is lower than 55℃ the passivation film's structure is more steady, when the temperature is 55℃ its stability tends to worsen and when the temperature exceed 55℃ its stability declines.
Abstract: The two-step method of calculating ODF (orientation distribution function) from pole figure as the basic principle was used to precisely analyze cubic system material texture. The Euler space was divided by 1° minimum unit. All of the divided spot's orientation density were calculated all over the orientation space. In addition, the corresponding analysis system was established. By means of the analysis system the textures of coldrolled and annealed IF steel specimens produced by Angang were calculated and were compared those with the sophisticated ODF calculation system by the Euler angle 5° minimum unit. The results show that the analysis system by the Euler angle 1° minimum unit can more exactly express the texture distribution than by the 5° minimum unit.
Abstract: The Taylor-type and finite element polycrystal model were incorporated into the commercial finite element code ABAQUS on the basis of the crystal plasticity theory of rate-dependent polycrystal constitutive relations. Initial orientations obtained by electron backscatter diffraction (EBSD) were directly input into the crystal plasticity finite element model (CPFEM) to simulate the rolling texture of fcc 1050 pure Al at two stains. Comparisons of simulated and experimental results showed that texture predictions of cold rolling by the finite element model were more approximate to the experiment result. The Taylor-type model predicted that orientations accumulated in the {4411} <11118> orientation which would be called Dillamore orientation. The finite element model predicted the copper orientation that was more approximate to the experiment result than Taylortype model. No {011} <211> brass orientation, {123} <523> S orientation, {011} <100> Goss orientation and other ideal orientations were simulated.
Abstract: ZrW2O8 was economically synthesized from ZrOCl2·8H2O and H2WO4 through co-precipitation route. The phases of the synthesized powders were analyzed by X-ray diffraction (XRD), the morphology was observed by scanning electron microscopy (SEM), and the synthesized temperature was determined by differential thermal gravimetric analysis. The result reveals that the suitable pH value of co-precipitation of Zr4+ and WO42- was 2-3. After the precursor was heated at 1200℃ for 1 h, the main phase of the synthesized powders was ZrW2O8. The particle size of ZrW2O8 powders wad about 100 nm and distributed homogeneously.
Abstract: Thermotropic phase transitions in the perovskite-type layer compounds n-(C12H25NH3)2MnCl4 and n-(C14H29NH3)2MnCl4 were synthesized and a series of their mixtures were prepared from ethanol solution. The nonisothermal kinetics of solid-solid phase transitions in C12Mn, C14Mn and their binary system was investigated by DSC. Kissinger and Ozawa methods were applied to determine the activation energy and reaction order of the solid-solid transitions, and the results of two methods are coincident. The value of activation energy Ea showed fluctuant with increasing XC12Mn. The reaction order of CnZn and their binary system is about 1.
Abstract: Grain gravity, buoyancy and gas drag were taken into consideration in burden trajectory calculation and the movement trajectory of a particle in chute and freeboard was computed. The influencing laws of gas drag on the landing point were analyzed according to the discussion about the variation of charging radius with different burdens in their range of grain diameter and the percent of gas drag. It is shown that the effect of gas drag should be considered for the precise calculation of burden trajectory, the landing points of particles are not the same because of their different density, size and shape factor, and burden distribution is influenced by the distribution of top gas flow.
Abstract: The effect of swirling nozzles with different processing parameters on the flow field in a mold is studied using numerical simulation. The results show that the high-temperature dissymmetry in the upper mold is increased a little by using a swirling nozzle, but the meniscus temperature and its uniformity are increased. The temperature difference between nozzle inner and meniscus is 15℃ for a traditional nozzle and 10℃ for a swirling nozzle. Increasing the casting speed or decreasing the blade height can increase the temperature at meniscus. When the swirling angle is 120° or the distance between blade and nozzle bottom is 390mm, the temperature of molten steel is the highest at meniscus.
Abstract: In order to meet the needs of prolonging the life of a blast furnace, a cast iron cooling stave with high performance was developed. The thermal boundary condition of the cast iron cooling stave with surface-alloyed cooling water pipes for numerical simulation of temperature field was determined by the use of hot test data. The commercial software ANSYS and the heat-structure coupling method were used to analyze the influence of furnace temperature, slag crust, edge contact pressure on the thermal stress and thermal deformation of the cast iron cooling stave under high-temperature condition. Effective measures were used to reduce the thermal stress of the cooling stave and control its thermal deformation. The new concept of high cycle heat loading, which evaluates the cooling capacity of cast iron cooling staves, was presented based on the strength analysis theory of spheroidal graphite iron.
Abstract: The three-dimensional thermo-electric solid and finite clement model of a great aluminum reduction cell was built based on general finite analytic software ANSYS. Simulation computing was processed with the double nonlinear affection of elasto-plastic material properties and contact problem taken into account, the stress contours and strain contours of cell wall and cradle rack were plotted, the deform law of the aluminum reduction cell's structure was analyzed, and some optimal measures were proposed for structure design. Reverse calculation was carried out under different load conditions on the assumption that the aluminum reduction cell was a elasticity body, and the best loading condition was achieved, which would offer a rapid and available research means for further design and reconstruct of an aluminum reduction cell.
Abstract: Ground granulated blast furnace slag (GGBFS) and steelmaking slag have been used as a raw material for cement production or as an aggregate to make concrete, which contribute aluminum, calcium, iron, and silicon oxides.The suitability of the slag for a particular application depends on its reactivity, cost, availability, and its influence on the properties of the resulting concrete.For the interest of durability studying of concrete in the presence of slag, the accelerated carbonation products and leaching behavior of the slag and Portland cement (PC) were studied.The experimental results confirmed that the slag was more resistant to carbonation compared to PC.The carbonation degree of GGBFS reduced by 17.74%;and the carbonation degrees of steelmaking slags reduced by 9.51%-11.94%.Carbonation neutralized the alkaline nature of the hydrated pastes and gave rise to the redox potential of the leachate slightly (30-77mV).The carbonation also increased the release of most of the elements presented, except for calcium, to the aqueous environment.It is concluded that blend cements (PC plus slag) have economical advantages and better durability compared to PC.
Abstract: Based on the method of imprecision (MoI) and the robust design, uncertainty factors which influences the quality of products were considered during preliminary design. Using MoI mapping from a design variable space (DVS) to a performance variable space (PVS), an aggregation function was built and incorporated in different performance preferences on PVS to accomplish aggregation preferences for multi-attributes or more estimating persons. The example of gearbox was illustrated an application of the aggregation function in the optimal decision making of robust design. The results show that it is a convenient and practical method.
Abstract: The net present value method was extended to fuzzy environment. A chance-constrained goal programming model for capital budgeting in fuzzy environment was proposed. A fuzzy simulation based on genetic algorithm was employed to provide a general solution for the new model problem. A numerical example was presented to illustrate the modeling idea and the effectiveness of the proposed algorithm.
Abstract: A state-space model based on discrete events was proposed to describe the network dynamic scheduling system. A number of heterogeneous jobs were concurrently taken into account. Upon describing the clearing policy of the network dynamic scheduling system, algorithms were developed for analysis of QoS (Quality of Services) performance parameters, which include queue length, total job number, the system's throughput, and response time of job request. Numerical calculations showed that the optimized scheduling policy could make the response time of the system within a controlled scope while the system's throughput was in a stable state.
Abstract: The general algorithms of local Web usage clustering (LUC) and global Web usage clustering (GUC) in a distributed data mining system based on multi-mirror sites were proposed, which better solved the troubles made by distributed Web access information and communication number. Java language was used to implement the algorithms and its performance was studied. The results showed that the algorithms were valid and could be effectively and accurately identified by Web user group patterns.
Monthly, started in 1955 Supervising institution：Ministry of Education Sponsoring Institution：University of Science and Technology Beijing Editorial office：Editorial Department of Chinese Journal of Engineering Publisher：Science Press Chairperson：Ren-shu Yang Editor-in-Chief：Ai-xiang Wu ISSN 2095-9389CN 2095-9389
