Abstract: A slope deformation model of metal mines transferred underground mining from open-pit based on support vector machines was presented. The model can effectively express the non-linear variation of metal mine open-pit slope deformation caused by underground mining disturbance. In the model the RBF kernel function was utilized to train on-site monitoring data, the cross-validation was employed to choose model parameters, support vectors were achieved with training samples, and then the future deformation was predicted. The model was applied to Xingshan Iron Ore transferred underground mining from open-pit. The results show that the regression value of learning samples is extremely precise and the predicted deformation has a higher precision based on support vector machines. The application of the model, which predicts the deformation with the achieved support vectors, is convenient and it bears a stronger generalization ability.
Abstract: On the basis of theoretic analysis and monomer testing, the composition and concentration of a dust suppressant used in tailings dams were determined initially, and then the best prescription was developed by the orthogonal test. The environmental adaptability simulation test of the dust suppressant in the laboratory were carried out, including compressive strength, water resistant, freeze-thaw resistant and wind erosion resistant. The result showed that the dust suppressant had a very strong ability of water resistant, freeze-thaw resistant and wind erosion resistant, and the shell compressive strength was 247 kPa. The dust suppressant was tested by field spraying in the tailings dam of a golden mine. The shell was continuous and integrated after going through the weatherbeaten for 203 days, and could bear strong wind (18 m·s-1) blowing. It is shown that the dust suppressant has very good dust suppressing performance and strong environmental adaptability.
Abstract: Vehicle velocity, road dust load, and dust moisture have close relationships with dust mass concentration. Based on orthogonal experiment and multiple regression statistical analysis, a calculation model of dust mass concentration in traffic was established, with a significance of 99% and a better goodness of fit. The results of significance test of regression coefficients show that the effects of the independent variables on the dependent variable are very significant, with the order of vehicle velocity, road dust load and dust moisture. The agreement of the computed results with test data indicates that the model has high reliability.
Abstract: The traditional methods of mineral and metallurgical processes are very difficult in treating the high-level phosphorus iron ore from west Hubei Province of China to meet the requirements of the iron and steel industry. A new technical route, gas-based reduction and electrical furnace melt separation, was proposed and demonstrated. Based on the mineral phases, thermodynamic simulation (performed with HSC) was carried out first, and then gas-based reduction experiment and electrical furnace melt separation experiment were conducted. Gas-based reduction results agree with the numerical simulation. The phosphorus content decreases from 1.28% in the ore sample to 0.27% in the final metal sample by using CO reduction and melt separation; and it decreases from 1.27% in the ore sample to 0.33% in the final metal sample by using H2 reduction. The melt separation SEM and EDS analyses of metal samples after melt separation show P exists as impurities. These impurities can be removed by refining methods in the melting stage to meet the requirements of steelmaking.
Abstract: The dephosphorization rate of converters was improved through optimizing the converter refining process and applying the method of multi-functional refining in converters on condition that any new equipment was not used. Based on the present converter condition, the temperature range of dephosphorization was obtained by thermodynamics calculation. The suitable time of slag tapping, alkalinity of slag, tapping temperature and the quantity of material were determined, and finally the optimal dephosphorization technique was confirmed. Comparing with normal refining, the quantity of material could be reduced and the dephosphorization rate was above 90% steadily by using the new technique. Besides, the quality of molten steel was improved and the cost of production was also decreased.
Abstract: Based on the experimental data of ultra-low carbon aluminum killed steel in a 300 t ladle of RH treatment, a model for predicting the total quantitatively oxygen content of molten steel was established. Some factors such as treatment time, argon flow rate, molten steel circulation rate, snorkel diameter, FeO and MnO content in ladle slag were considered in the model. Potential improvements for RH operation were discussed. According to model analysis, the methods for promoting inclusion rising are increasing the argon flow and enlarging the snorkel diameter, but they have proper ranges.
Abstract: The shock compression experiments of pure iron for shaped charge liners after annealing at 930℃ for 2 h were carried out with the split Hopkinson pressure bar apparatus, and its dynamic stress-strain relationships were measured at different strain rates. The microstructure of the deformed pure iron was examined by optical microscope. The microstructure evolution occurring at different strain rates and dynamic stress-strain behavior were investigated. It is shown that pure iron for shaped charge liners has the twinning structure after impact compression. The effect of work-hardening and strain rate strengthening for pure iron occurs at the strain rates of 650 to 3 850 s-1, and the maximum strain also rises with increasing strain rate. Twinning and slipping are the plastic deformation mechanism of pure iron under the shock of high strain rate, which leads to the increase in both strength and plasticity at high strain rate for pure iron.
Abstract: The effects of tempering temperature on the microstructure and mechanical properties of 600 MPa grade low carbon bainitic steel belonged to Fe-Mn-Nb-B series were investigated by utilizing scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that tempering temperature has considerable influence on both the yield strength and the tensile strength. The yield strength increases with increasing tempering temperature while the tensile strength has an adverse law. In comparison with the as-received steel, the yield strength of the steel tempered at 600℃ increases 105 MPa. With the increase in tempering temperature, the yield strength increase first and has a slight decline after it reaches the highest point at 600℃, the tensile strength decreases significantly, the elongation increases slightly and the yield ratio increases also. Through analysis it is concluded that the major change of mechanical properties after tempering has a connection with dispersive precipitates with the size of less than 20 nm, the decomposition of large M/A islands in which martensite has a large proportion and the reversion of dislocations and polygon ferrite.
Abstract: The fatigue fracture and crack propagation of XCQ16 and 20Mn2 axle steel were observed by SEM. Based on the observed results, the mechanisms of fatigue crack initiation and propagation were studied. It is shown that cracks initiate from the sample surfaces. The main mechanism of crack initiation is non-metallic inclusions and dislocations. The crack closure effect of XCQ16 steel is stronger than 20Mn2 steel in crack propagation areas, leading to a lower crack growth rate. The fracture mechanisms of the two steels are different:plastic fracture for XCQ16 and cleavage fracture for 20Mn2. Non-metallic inclusions in XCQ16 are composed of oxide inclusions and sulfide inclusions, but mainly oxide inclusions in 20Mn2 steel. The mixed inclusions in XCQ16 steel have less effect on its fatigue property.
Abstract: The mierostructure and toughness in the welding heat affected zone (HAZ) of boron containing high-strength low-alloy (HSLA) steel plates were investigated by means of thermal simulation with a Gleeble thermal simulator. The results show that the toughness in the overheated zone decreases significantly with the increase of cooling time t8/3. When t8/3 below 67 s, the impact toughness in the overheated zone is higher, the structure is lath martensite or lath martensite + bainite, and the grain is finer. Since the impact toughness in the HAZ and weld joint of 800 MPa grade low carbon bainitic steel is higher, the welding process which are 0.96-2.11 kJ·mm-1 heat input, 150-200℃ interbead temperature and heat treatment after welding has a high adaptability to the low carbon bainite steel.
Abstract: The relation of equilibrium hydrogen pressure with temperature and the hydrogen absorption kinetic behavior of TC4 compacts were investigated with a tubular hydrogen treatment furnace. The rate constant, reaction mechanisms and activation energy of hydrogen absorption at different temperatures were also determined. It is found that the time to reach equilibrium decreases with increasing temperature, but the equilibrium hydrogen pressure increases with increasing temperature. The hydrogen absorption process at 350℃ is controlled by the nucleation and growth, power law and three-dimensional diffusion, the hydrogen absorption process at 400℃ is controlled by the power law and three-dimensional diffusion, while the hydrogen absorption process from 450 to 750℃ is only controlled by the three-dimensional diffusion. The activation energy for hydrogen absorption by TC4 compacts is found to be 14.55 kJ·mol-1.
Abstract: A hypereutectic Al-Si alloy with 25% (mass fraction) Si was prepared by traditional cast and spray forming processes, and its microstructures, melting and precipitation processes were studied using SEM(EDS), XRD and DSC methods. The results show that the cast alloy contains coarse plate primary silicon phase and coarse needle-like Fe-bearing phase, but the sizes and morphologies of coarse primary silicon phase and coarse needle-like Fe-bearing phase can be improved by spray forming process so as to improve the properties of the hypereutectic Al-Si alloy. Al matrix, primary silicon phase and Al2Cu phase are present in both the cast and spray-formed alloys, but the difference is that the main Fe-bearing phase in the cast alloy is Al4FeSi2 as well as β-AI5FeSi phase does in the spray-formed alloy. The main reason is that the cooling rate of the as-deposited preform decreases due to the existence of mushy layer on the preform surface so that the phase transformation about Al4FeSi2 phase can be occurred and the eutectic microstructure increases, and β-Al5FeSi phase can dominate Fe-bearing phase in the spray-formed alloy. The melting and solidification process of phases in the spray-formed alloy was discussed via DSC experiment.
A fluorescent technology for corrosion prediction of aluminum alloys based on a coating containing a complex (AlQ3) of aluminum ions with 8-hydroxy-quinoline (8HQ) was studied. The effects of aluminum ions and pH on the fluorescence characteristic of 8HQ were investigated. It was found that the intensity of AlQ3 was increased with the concentration of aluminum ions. The 8HQ was embedded into the surface of the aluminum alloy and then further coated by a transparent epoxy coating to make samples. The samples made by this technology were exposed to a salt spray box. After salt spray tests, fluorescent spots were observed clearly under UV light whereas no obvious change was seen under visible light. The corrosion pitting on aluminum alloy substrates was observed at the fluorescent spots by an optical microscope, It was proved that the fluorescent spot size and intensity were increased with the aggravation and enlargement of corrosion area with corrosion time.
Abstract: High volume fraction Cu/diamond composites were successfully prepared by spark plasma sintering (SPS). Their relative density, thermal conductivity and coefficient of thermal expansion (CTE) were investigated. It is found that the composites have a uniform microstructure, with the relative density from 94% to 99%, the highest thermal conductivity of 305 W· (m·K)-1, and the CTE matching with common electronic semiconductor materials. All these properties can meet the demands of electronic packaging materials.
Abstract: With glutaraldehyde as finishing agent, the surface of an up-conversion luminescent material, Na[Y0.57Yb0.39Er0.04] F4, was modified with aldehyde groups by surface grafting modification. FI-IR proved that aldehyde groups existed on the surface. The quantity of aldehyde groups was 1.38 ×103 mol·g-1 which was detected by UV. Qualitative TGA indicated that there were organic groups on the surface. The particle diameter of the modified up-conversion luminescent material was aggrandized in SEM. In settlement testing, the modified up-conversion luminescent material has more favorable dispersion stability than un-modified materials.
Abstract: Y2O3 thin films were successfully deposited onto Si (100) substrates by the electrostatic spray assisted vapor deposition (ESAVD) method. The films were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The results of FE-SEM analysis showed that Y2O3 thin films were homogeneous, uniform and nanostructural. AFM analysis indicated that Y2O3 thin films had low surface roughness(11 nm). XPS analysis results showed that the deposited thin Y2O3 oxide films were close to their stoichiometry. The coalescent strength of the Y2O3 film to the Si substrate was 4.2 N. XRD patterns indicated that Y2O3 thin films with (111) oriented growth were obtained after heat treatment, whilst the Y2O3 thin films were amorphous before heat treatment.
Abstract: The transmission properties and magnetotunability of a magnetoinductive device with bilayered ferrite structure were investigated, and the effect of structural parameters on the properties of microwave was discussed. When two magnetized ferrite slabs are parallelly placed, the coupling of the resonanting modes of surface wave results in magnetoinductive wave, which propagates across the composite structure. In the transmission spectra, a passband appears in the frequency range of the forbidden band which is produced by ferromagnetic resonance. The center frequency of the passband shifts to a higher frequency when the bias magnetic field increases. That is good magnetotunability. With the increase of the distance between the two ferrite slabs, the coupling between surface waves fades gradually, the half-width decreases, and the transmission loss increases.
To keep micro molten pools stable is a premise for fabricating glass-coated metal microwires continuously by the glass-coated melt spinning method. Theoretic calculation was used to analyze the effects of the structural parameters of an induction heater, heating current, pool volume (mass) and position in the induction heater on the temperature and levitation force of the Fe-based alloy micro molten pool. The levitation force of the micro molten pool, as the temperature is 1280℃, increases with the increase in cone angle and bottom hole height of the induction heater, as well as the decrease of the induction heater's height, bottom hole radius and distance from the molten pool center to the upper surface of the bottom hole, and reducing the heating current and the pool volume (mass) is beneficial to the decrease of the difference between gravity and levitation force. The appropriate structural sizes of the integral induction heater for preparing glass-coated Fe-based alloy microwires are the cone angle of the induction heater 120 to 130°, height of the induction heater 12 to 14 mm, bottom hole height 2 to 4 mm, and bottom hole radius 3 to 4 mm. The reasonable distance from the molten pool center to the upper surface of the bottom hole is 4 to 6 mm and the suitable mass of the Fe-based alloy micro molten pool is 1.5 to 2.0 g. Using the optimized integral induction heater and keeping the volume (mass) of the Fe-based alloy micro molten pool almost invariant by feeding continuously, glass-coated Fe-based alloy microwires are fabricated continuously and stably.
Abstract: To study the deformation of heavy section shrinkage cross wedge rolling, experiments with section shrinkages much larger than 75%, which is usually regarded as the section shrinkage limit of single wedge in cross wedge rolling, were done. In the experiments, a work piece whose section shrinkage is 97.7% was successfully rolled. A formula of resultant axial force on the contact zone of the work piece was deduced. Axial stress in the symmetrical section of the rod part was analyzed by the three-dimensional finite element method. The reason that the heavy section shrinkage can be rolled by single wedge is that under proper conditions the axial forces on the contact zone of the work piece are nearly in an equilibrium state, and thus the axial tensile stress on the rod part of the work-piece is reduced.
Abstract: A 2250 hot temper mill was first adopted in WISCO (Wuhan Iron & Steel (Group) Corp.) of China for wide strip production and it has both HCW and WRS mill type characteristics. During operation, some problems were found, for example, work rolls were worn badly and non-uniformly, there were especial adjusting phenomena of work roll bending force, and shape control was not satisfied. Continuous tracking measurements were carried out and the typical characteristic of W-shape work roll wear was found in a roll serving period. The influence coefficient of roll wear was proposed for analyzing the W-shape wear. The synthetical influences of work roll wear, bending force and axial shifting on the shape control were studied. The especial adjusting phenomena of work roll bending force were analyzed and explained on the base of trials. It is pointed that, with the roll wear increasing, the occurrence of Wshape work roll wear leads to the decrease in gap crown because of the positive crown of the work roll within the strip width range, and the method of gradually changing the bending force from positive to negative is to increase the gap crown for compensating the decrease in gap crown caused by work roll wear and axial shifting, which makes the loaded gap invariant.
Abstract: The performance of a pressure swing adsorption (PSA) oxygen system with new tandem-type adsorbers was experimentally investigated. The effects of operating parameters, such as production duration, pressure equalization mode, product flow rate and adsorbents' properties, on the product purity and recovery of the new PSA oxygen system were analyzed. The experimental result indicates that there is the best production duration in the feed step. The product recovery is better when the product flow rate increases, whereas the product purity reduces. The pressure equalization step in the adsorber's two-inlet can improve the product purity and recovery extensively. The product recovery achieves 32% when the product purity is greater than 92% in the experiment.
Abstract: An adaptive algorithm was improved and introduced to the particle swarm optimization algorithm (PSO). When the population evolution reaches certain generations, the search area is changed in accordance with the improved adaptive algorithm. It is achieved that the search area is revised automatically to increase the convergence rate and precision and prevent the premature convergence of the particle swarm algorithm. The conclusion was verified through simulation. Finally, the new algorithm was applied to the optimum design of scheduling hot strip mills, whose running time was less than 5 s, which validated the real-time application to provide an effective way to optimize.
Abstract: In order to make planning and scheduling for cold-drawn seamless steel tube re-entrant lines, workpieces were grouped together according to four conditions, then the grouped steel tubes were taken as one workpiece through the assumption of conditions. The model of multi-objective order-grouping scheduling optimization was studied, where the final completion time, the delivery satisfaction and the total load of machine were concerned. In addition, the constraint conditions were put forward. The Pareto-based hybrid genetic algorithm was used to make the optimal solution of the model. The effectiveness and rationality of the optimization model was proved by an example.
Abstract: According to the rough sets theories, rules can be extracted from the control data of a two-cell immune controller. With a new criterion proposed in this paper, the best rules were selected to compose the rough-regularized two-cell immune controller. From a normal two-cell immune controller to a rough-regularized two-cell immune controller, the characteristic of self-learning and anti-delay can be inherited, which is proved through a simulation. The better anti-disturb ability and faster response were also demonstrated.
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
