Abstract: In order to promote mine gas hydrate formation quickly, which can prevent coal and gas outburst, the processes of gas hydrate formation in three reaction systems containing coal were investigated by utilizing the visible experimental installation under the condition of 14.3-25.4℃ and 18.66-26.70 MPa, and the correlations among pressure, temperature and time were obtained. Experimental data were analyzed based on the computation models of formation rate and volumetric proportion. The results show that the addition of surfactant shortens induction time and improves formation rate and volumetric proportion, and the volumetric proportion of synthetic hydrate samples can amount to 136-150; the existence of porous medium (coal) delays hydrate formation exiguously; the influence of memory effect on gas hydrate formation is notable, the induction time could be shortened by 10-20 times for the experimental system containing residual pentahedral ring structure.
Abstract: The influences of column diameter and height on the countercurrent flotation process were discussed, and the new concepts of choked air bubbles and area load were put forward. By studying the force and movement of mineralized bubbles, a theoretical model expressing pulp movement was set up and model parameters were treated by experience. The column diameter was designed based on the pump velocity, and the column height was designed based on the column diameter and the column. Experiments were carried out to process molybdenum bismuth fine ores. The experimental results show that under the same test conditions, both the concentrate grade and the concentrate recovery of the flotation column whose size is designed based on this method are higher than those of other size flotation columns.
Abstract: A painter algorithm was proposed to better solve the disappearing problem of ore body when ore body was displayed in a graphics equipment. After taking four steps of merging plane polygon, decomposing polygon graphics into triangle graphics, sorting triangular surface treatment and building up triangle graphics for depth, ore body was disposed by the painter algorithm, and hidden line or body warded off by opaque body or other entities in original entities would be not output. When ore body was showed and printed by the graphics equipment, underground mining engineering body would be more realistic.
Abstract: The effects of carbon and nitrogen sources as well as carbon-to-nitrogen mass ratio on the growth of Chlorella sp USTB01 and the production of lutein were investigated under the condition of heterotrophic culture in.dark. The results show that glucose and potassium nitrate were the best carbon and nitrogen sources to support the rapid and continuous growth of Chlorella sp USTB01 respectively. When glucose and potassium nitrate were used as the sole carbon and nitrogen sources and the initial concentration of nitrogen was 0.28 g·L-1, the growth of Chlorella sp increased with the increase of carbon-to-nitrogen mass ratio in the range from 15 to 25. Potassium nitrate was the best nitrogen source to promote biosynthesis of lutein by Chlorella sp USTB01 and the content of lutein in the cells of Chlorella sp USTB01 declined with the increase of carbon-nitrogen mass ratio from 15 to 30.
Abstract: The formation and transformation of non-metallic globular inclusions (Type-D inclusions) in bearing steel production were studied. There were different kinds of Type-D inclusions in the commercial specimens of bearing steel from SEM inspection. Al content had important effect on the inclusion formation in the experiment of an induction furnace. A great amount of MgO·Al2O3 formed with high Al deoxidation in MgO crucible melting. With high content of Ca, the inclusions of MgO·Al2O3 spinel will become calcium-aluminates entirely. The results show that the contents of Ca, Mg and Al in liquid steel have important effect on the formation of Dtype inclusions. It is tested in the experiment of bearing steel production that Type-D inclusions can be improved by specific slag modification and composition optimization.
Abstract: To research the major type of inclusions in stainless steel slabs and find out their primary origin, the composition of the non-metallic inclusions was analyzed by SEM, and three tracer experiments were performed by adding a tracer into AOD slag, ladle slag and tundish slag, respectively. The results show that the primary non-metallic inclusions in 0Cr18Ni9 stainless steel slabs is CaO-SiO2-Al2O3-MgO system inclusions, the second is MgO-Al2O3 spinel and sulphide; the primary origin of the non-metallic inclusions is the production of deoxidation and desulfuration during AOD reducing and the AOD slag suspension in the molten steel during tapping; after tapping, the molten steel is not obviously polluted by ladle slag, tundish covering flux and mold flux.
Abstract: The effects of flow control devices, casting speed of liquid steel and inclusion size on inclusion removal in a continuous casting tundish were investigated by choosing emulsion drops to simulate inclusions in a water model. The results show that the efficiency of inclusion removal in the tundish with weir and dams is relatively high due to the collision and aggregation of inclusions in high turbulence region and the improvement of flow field in the tundish. Although adding turbulence inhibitor into the tundish changes fluid flow little in pouring region, it has not much effect on the efficiency of inclusion removal. It seems to be difficult to improve the efficiency of inclusion removal only by optimizing the flow control devices in the tundish with high casting speed of liquid steel.
Abstract: The calcium content for inclusion distortion and the formation condition of sulfuric calcium in calcium treatment were calculated by thermodynamics method. The maximum content of sulfur after LF treatment and the minimum content of calcium after calcium treatment were determined. The effect of temperature and amount of feeding calcium on the yield of calcium and the relation between the soft argon blowing time after calcium treatment and the loss of calcium and aluminum were investigated. Based on calculation and experimental data, the process of calcium treatment was optimized, and the mass fraction of sulfur in steel after LF treatment is no more than 0. 007%. For each heat, feeding 100-200 m calcium line and blowing soft argon for 25 minutes after calcium feeding, the percent of pass of inclusions in the cold heading steel can reach up to 92%.
Abstract: Serious sampling and integrated analysis were carried out in the production of pipe steel with LF-VD, RH-LF and LF-RH refining processes. It is shown that high grade pipe steel can be produced with the three refining processes, but the purity and cleanness of the steel produced with LF-RH process are higher; the functions of different refining instruments are distinct, but they are affected effected by up and down working procedures because of the conjunction and restriction of the quantity and composition of refining slag and other factors.
Abstract: Molten steel was treated through changing the voltage of pulse electric field, the effect of pulse electric field on the refinement of crystal particles and the transfer of elements in solidification process was investigated. The number and distribution of crystal particles in steel was analyzed using the software ImageJ. The distribution and segregation of main elements in the solidification structure of steel were studied by original position analysis (OPA), and the effect of the voltage of pulse electric field on the transfer of elements in solidification process was discussed. The results showed that the crystal particles were obviously refined with increasing pulse voltage, and there was a similar distribution characteristic for the elements Si, Mn and P but reverse for the elements P and S.
Abstract: The microstructure, dislocation and precipitation phases of X80 pipeline steel produced with different processes were analyzed by optical microscope and transmission electron microscope contrastively, and the influence of structure pattern on the performance of X80 pipeline steel was studied combining with tests of mechanic properties. The result shows that the effects of acicular ferrite grain size, precipitate phrase distribution, dislocation density and form on the material strength, toughness and brittle transmission temperatures were distinct, and solid solution strengthening, fine crystal strengthening, dislocation strengthening and precipitation strengthening were the strengthening ways of X80 pipeline steel.
Abstract: A method to prepare chemical manganese dioxide by directly oxidizing manganese hydroxide with air in the presence of catalyzer was investigated. The processes of the method included that manganese hydrolyzate was prepared by hydrolysis of manganese sulfate in ammonie medium, the hydrolyzate furthermore hydrolyzed to manganese hydroxide, and manganese hydroxide was oxidized to MnO2 at certain temperature with ir in the presence of catalyzer. The research results indicate that the oxidation rate of manganese hydroxide is slow and the obtained oxidization product contains MnO2 less than 66%. The catalyzer R can elevate the oxidization rate of manganese hydroxide, which is influenced by temperature and the particle size of manganese hydroxide. Elementary manganese dioxide with MnO2 more than 83% and an apparent density of 1.7-1.8 was yielded in the presence of the catalyzer R and by utilization of optimized reaction parameters.
Abstract: An assumed strain finite element method based on the theory of strain gradient was proposed to explore the size effect that frequently exhibited in micro-beam bending. In element design, strain gradient terms were obtained by using numerical integration of a cell constructing around a Gaussian point. An equivalent strain gradient term was incorporated into the constitutive model to reflect the effect of highly localized inhomogeneous deformation. In this way, an assumed strain finite element method program was developed. To validate the performance of the proposed method, a numerical simulation of micro-beam bending was carried out. Numerical resuits show a good agreement with the reported experimental data. It is concluded that the proposed approach is of good capability to reflect the response of microstructure.
Abstract: To control slag entrapment, a new method was put forward to calculate the level fluctuation index, i.e. F value, which was defined by other researchers. F value could easily be calculated based on the results of numerical simulation of slab continuous casting mold flow. The relationship between F value and level fluctuation in the mold as well as operational technological parameters were also studied. It is shown that using the data of numerical simulation of slab continuous casting mold flow can easily calculate F value. By adjusting operational technological parameters, the range of F value can be controlled in 3 -5, and the surface fluctuation in ± (3-5) mm, as a result, slag entrapment can be avoided.
Abstract: Based on the coupled model of turbulence and multiphase fluid flow, the flow behavior with free surface fluctuation in a bloom casting mould was numerically simulated. The influence of nozzle outlet angle on the fluid flow and free surface oscillation in the mould was analyzed. The results show that when the downward nozzle outlet angle increase by 5°, the impinging spots descend by 13 mm and 10 mm at the wide faces and narrow faces respectively. At a given submergence depth of 100 mm, outlet angle show limited influence on the fluctuation within 3 mm. The fluid close to mould wall is more active than that close to nozzle. The nozzle outlet angle of 20° is recommended to use.
Abstract: Based on the coupling numerical solving method, the velocity distribution and flow behavior of Ar in a ladle furnace lid was calculated and analyzed by numerical simulation. The results show that the appropriate off-gas pressures in the periods of emerged arc and submerged arc are -200- -250 Pa and -120 Pa, respectively. When the bottom blowing rate is very small, argon cannot disperse on the top of the molten steel surface; as the Ar-bottom blowing rate increases to 20-50 m3·h-1, argon can be dispersive and its flow distribution is similar near the molten steel surface, which is in favor of retaining inactive gas Ar. With the augment of the distance from the molten steel surface to the top ladle edge, the circulating region of Ar enlarges on the top of the molten steel surface, which is in favor of avoiding the increase of[O] or[N] in molten steel.
Abstract: In order to realize domestic manufacture of a large rolling mill and reduce investment of equipment, the manufacture technology of a large strip rolling mill stand was studied considering the characteristics of a 2 250 mm hot rolling mill and a 2 130 mm cold rolling mill in Maanshan Iron and Steel Co. Ltd. Through preassembling and debugging, the manufacture precision and properties of the rolling mill stand met the demand. The results of industrial testing on 2 250 mm hot rolling sheets and 2 130 mm cold rolling sheets show that under the condition of ensuring the rolling mill's quality the investment of equipment reduces and the manufacture time shortens.
Abstract: A mathematical model of charging characteristics in a full power hydraulic brake system was established based on the structure and performance analysis of a new-type accumulator charging valve. The simulation analysis of dynamic characteristics and power expending of the charging valve were conducted, and the affecting laws of the valve's system parameters and structure parameters on the charging characteristics of the system were learned. Experiments are carried out to verify the simulating model.
Abstract: Based on the principle of gear mesh and hob designing, a method to design an asymmetric involute spur gear was provided and the calculation formula was deducted. The parameter solid model was set up using a calculation example. On the base of the principle of gear manufacture, parametric programs programmed with Visual Basic software and Autolisp program were separately introduced to simulate the envelope process of asymmetric gear manufacture. The result shows this method provides a foundation for new-style asymmetric gear manufacture and experimental study.
Abstract: To research the effect of air damping on resonators, based on the Euler-Bernoulli assumption, beam vibration mechanism and air damping theory, a vibration equation was established and its solution was obtained according to corresponding boundary conditions. The air damping influences on the resonant frequency and quality factor of a micro-beam resonator were obtained under two different conditions. By analyzing air damping in two different ways, it is found that a critical squeeze-film thickness exists under the condition that the aspect ratio of the beam is constant, and the obtained expression of critical thickness can give some suggestions to devices designing.
Abstract: On the basis of the production run research of a BOF steelmaking workshop, the matching analysis and comprehensive research of productive capacity among BOFs, LFs and CCMs were carried out from the aspect of basic mass flow parameters. Applying OPT technology to this study, the bottleneck of coordinating operation for the previous process was the continuous casting machine (CCM), which was determined through analyzing three ways to enhance productive capacity. The optimized scheme of productive capacity matching for different working procedures was put forward, which was the strands of CCM increased from 4 to 5 in the former process of the steelmaking plant. At last, the matching mode of converters, LFs and CCMs in the medium and small size BOF process was discussed, and the matching mode of one BOF-one LF-one CCM is feasible on some condition.
Abstract: Using traditional methods to analyse the safety of industrial projects, safety benefit and value can only reflect the safety situation of system partially, the effect of analytical results on improving the safety situation of system is limited and its application is not satisfied. By introducing the theory of value analysis, safety benefit-value simultaneous equations and optimization criteria were built. Integrating the only area chart, the function area method (FAM) was finally developed. By applying this method to engineering projects, the only area chart and curves were obtained based on the technical parameters of projects, and the safety value and cost of projects were greatly improved.
Abstract: A sort of incremental learning algorithm for support vector machine based on clustering was proposed. The nearest neighbor clustering algorithm was used for separating a whole training data set into several clusters, and each cluster subset was trained by support vector machine to obtain the support vector subset. The new sample data was firstly clustered in a certain subset. Then the distances between the new sample data and the support vectors of the cluster subset were calculated to weight every support vector. Finally, a new weighed model was formed with these samples. The proposed method was applied to a practical case of modeling prediction ability of the mechanical properties of steel materials. Comparing with the traditional support vector regression algorithm, this proposed method demonstrates its advantages of the smaller number of support vectors and the better generalization capability.
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
