Abstract: The constraint of complex geological conditions and the high heterogeneity of oil reservoirs make filtration resistance vary greatly in the process of water flooding. Fluid tends to flow along high permeability formation with low resistance, leading to a smaller reservoir swept volume and a lower producing degree. In order to control the resistances of all channels in the seepage field to balance the resistances as much as possible, a new method of controllable displacement of equivalent filtration resistance with several slugs was presented. A series of mathematical models were established for describing complicated controllable displacement on the basis of the mass transport fluid mechanics, the material balance principle and the characteristics of each slug. After simplification the one-dimension analytical solution was derived through integral transformation. Combined experimental results with the theoretical analysis of pressure distribution calculated by the filtration theory, it is demonstrated that the controllable displacement of equivalent filtration resistance with several slugs can greatly enlarge the swept volume, reduce the water cut, activate oil in the low permeability reservoir and enhance the oil recovery.
Abstract: Based on the structural dynamic theory, the relationship between capacity spectra and lateral load patterns was demonstrated. It was pointed out that different formulae of capacity spectrum curves should be used for different lateral load patterns and the formulas were given. A six-story reinforced concrete frame structure was designed and analyzed using the proposed method, the classical method and the time history analysis method respectively. The result shows that the proposed method is more accurate. Using the proposed method and the different lateral load patterns the seismic response can be bounded within a narrower scope, which will help to know the seismic response more accurately.
Abstract: The bioleaching of nickel-molybdenum sulfide ores with the thermophilic and acidophilic lithotroph, Metallosphaera sedula, with shaking flasks was studied in order to probe a more efficient and sustainable biometallurgical way. The result shows that the leaching rate of Ni with MetaUosphaera sedula was all more than 91%, but that in the groups without Metallosphaera sedula was 77.64%. The leaching rates of Ni and Mo in the groups with adapted Metallosphaera sedula cultured with Fe2+ were 96.56% and 65.43%, those in the groups with unadapted Metallosphaera sedula 94.37% and 60.20%, respectively. The leaching rates of Ni and Mo in the groups when the initial pH was 2 were 97.55% and 62.97% respectively. The leaching rates of Ni in the groups with the sizes less than 0.048 mm and 0.077 mm were 97.58% and 95.37%, while the leaching rates of Mo were 64.46% and 59.54%. The leaching rates of Ni and Mo in the groups with an ore mass concentration of 5 g· L-1 were higher than the more ore content and reached 98.67% and 81.87% respectively. In the groups with 0.5 g· L-1 Fe3+ added and the contrast group without Metallosphaera sedula, the leaching rates of Ni were 91.19% and 77.64% respectively, while those of Mo were 52.25% and 50.19%. The leaching rates of Ni and Mo in the dialyzing group were lower than those of the undialyaing group. The leaching rates of Ni and Mo in the groups with Metallosphaera sedula were 94.01% and 64,74% respectively, while just 67.77% of Ni and 38.16% of Mo were leached out in the groups with Acidthiobacillus ferrooxidans.
Abstract: The flowsheet of the selective flotation of lead and the activation flotation of copper was adopted to recover lead and copper from cyanide tailings. Closed circuit test results show that the qualified lead concentrate with the recovery of 90.48% and the grade of 45.24% can be produced with lime as a stabilizer, sodium diethyl dithiocarbamate (N, N-diethyldithiocarbamate) and butylxanthate (butyl sodium xanthate) as combined collectors, and by using the flotation flowsheet of one roughing, two scavengings and two cleanings. The qualified copper concentrate with the recovery of 82.17% and the grade of 19.28% can be produced with NP (a combined reagent by inorganic copper salts and inorganic zinc salts) as an activator, organic depressant FM as a stabilizer, Z-200 (O-isopropyl-N-ethyhhioearbamate) and butyl ammonium aerofloat (ammonium dibutyl dithiophosphate) as combined collectors, and by using the flotation flowsheet of one roughing, two scavengings and two cleanings. Gold and silver are also simultaneously enriched within the two kinds of concentrates.
Abstract: Inclusions in liquid steel were removed with fine dispersed heterophases induced by the explosive reaction of composite spheres in a RH ladle. The composite spheres were produced with a rotating plate granulator and fed into liquid steel at the end of RH refining for industrial tests. The results indicate that the inclusion removal technology is of low cost, high efficiency and easy to operate. It can obviously decrease non-metallic inclusions in liquid steel in about 10 min. In comparison with conventional methods, the number of oxide inclusions decreases to a lower level, the inclusion size becomes finer, the total oxygen in the as-cast slab can approach to 6 × 10-6 and the production cost for per ton of steel can be reduced by 5 to 10 yuan RMB.
Abstract: Rust layers formed on the surface of Q235 steel subjected to a high temperature and high humidity marine atmosphere in Xisha Islands were characterized by electron probe micro analyzer,Raman spectrum and so on.The results showed that the rust layer after one-month exposure was thick and there were many cracks and holes in it.The rust layer exposed for three months was thinner than one month's.The outer rust layer of carbon steel was mainly composed of β-FeOOH,γ-FeOOH,α-FeOOH and a little Fe3O4 after one-month exposure.Iron oxides such as Fe3O4 and γ-Fe2O3 were found in the inner rust.The evaporation of electrolyte pricked up in the inner of a loose rust layer with exposure time.Much FeOOH which was oxidized from iron oxides was found in the inner rust after three-month exposure.Some γ-FeOOH transformed to α-FeOOH at the same time.Q235 steel continuously corroded in the Xisha atmosphere,which was caused by the recycle of oxidizing and deoxidizing of the rust.
Abstract: 1 000 MPa grade hot dip galvanized dual phase steel was produced by simulating the process of hot dip galvanizing.The fracture behavior of the dual phase steel was observed by in-situ tension experiment,and its fracture mechanism was further analyzed by SEM and TEM.The results show that dual phase steel(F+M) with a tensile strength of 1 022 MPa and an elongation of 9.5% can be obtained when the annealing temperature is 820℃.During the process of dynamic tension,new micro-cracks initiate in the plastic zone of crack tips and wave-like slip bands generate in ferrite grains in the plastic zone.When the crack meets martensite,it changes its propagation direction and get around the martensite island;but when the crack meets ferrite,the ferrite grain is plastically broken up through the way of joining micro-pores.The final fracture pattern is plastic fracture and the fracture morphology of the sample is a dimple pattern.
Abstract: A new-type high-manganese austenitic alloy for immersed rolls in continuous hot-dip coating lines was developed.The corrosion behaviors of the high-manganese austenitic alloy in molten zinc at 490℃ were systematically studied in order to better understand the reaction mechanism.The results indicated that the high-manganese austenitic alloy showed a better corrosion resistance than 316 L stainless steel.Its corrosion rate in molten zinc was calculated to be approximately 6.42×10-4 g·cm-2·h-1,but 1.54×10-3 g·cm-2·h-1 for 316 L stainless steel.The ultimate corrosive products of the high-manganese austenitic alloy were Γ,δ and ζ phases,while that of 316 L stainless steel was almost ζ phase.δ phase in the high-manganese austenitic alloy contains about 8.5% Cr,and the existence of Cr improves the stabilization of δ phase.This δ phase with enrichment of Cr acts as a barrier slowing down the reaction of Fe and Zn,and improves the corrosion resistance of the high-manganese austenitic alloy.Substituting manganese for nickel to manufacture a high-manganese austenitic alloy of low cost is feasible.
Abstract: The effects of 0.025% Nb microalloying on the microstructure and mechanical properties of high-Al cold-rolled TRIP steel were investigated by means of two-stage salt bath heat treatment,optical microscopy(OM),scanning electron microscopy(SEM),X-ray diffraction(XRD) and tensile test.The results indicate that the addition of Nb refines the microstructure after continuous annealing and increases the volume fraction and carbon content of retained austenite.The Nb-microalloyed high-Al TRIP steel treated at 370℃ or 400℃ has very excellent mechanical properties,the tensile strength is higher than 650 MPa and the total elongation is above 35%.The best isothermal bainitic transformation process of the Nb-alloyed TRIP steel is from 370℃ to 400℃,which is wider than that of the TRIP steel without Nb,at about 400℃.The consistency of the process is enhanced.
Abstract: Based on the universal problem of steel pipes' corrosion and scaling in the transportation of geothermal water, the environmental conditions of geothermal water in the Chinese central plains was simulated to study the scaling and electrochemical corrosion behavior of 304 stainless steel pipes. The experiments results indicated that the scaling process of 304 stainless steel pipes in the simulated geothermal water was divided into two states, one was the nucleus-forming state, and the other was the nucleus growth state. The reducing rate of scaling ions in the nucleus-forming state was more than that in the nucleus growth state. The microcosmic appearance of scaling was straw-like abnormity. In addition, the change in temperature of geothermal water could accelerate 304 stainless steel's sensitivity of pitting corrosion, and the protective performance of 304 stainless steel's passive film decreased as the temperature of geothermal water increasing.
Abstract: 316 L stainless steel powders were prepared by supersonic gas atomization.The characteristic of the powder particles was investigated by means of laser particle size analyzer,scanning electron microscopy(SEM),optical microscopy(OM) and X-ray diffraction(XRD) technique.The result indicates that the mass median particle diameter is about 24 μm and the geometric standard deviation δ is 1.75.Three main types of solidification microstructures were observed in the powders:well-developed dendrite,cellular and a mixture of dendrite and cellular.XRD measurements show that γ-austenite phase is found in the big particle while small particle is a composite consisting of δ-ferrite and γ-austenite phases.The cooling rate is inversely related to the particle size,i.e.,it increases with decreasing particle size.The mean cooling rates of melt droplets range from 104 to 107 K·s-1.
Abstract: Some analytical methods including XRD,SEM and TEM were used to study the surface microstructure of oriented silicon steel,and the effect of insulating coatings on the iron loss of oriented silicon steel was analyzed with a magnetic property gauge.The results show that the insulating coating consists of two layers,one is Mg2SiO4 and the other is a phosphate coating.No diffusion occurs between the substrate and the Mg2SiO4 layer,indicating that adhesion is dependent on the shape of Mg2SiO4 crystal grains.Some Mg2SiO4 grains grow into the substrate and enhance the coatings' adhesion,but increase the iron loss.
Abstract: The effects of B and Cr additions on the magnetostriction and mechanical properties of polycrystalline Fe83Ga17 alloy were investigated.It was found that 1%(atom fraction) addition of B increased the magnetostriction of the Fe83Ga17 alloy and improved the room temperature ductility and tensile strength.Compared with the Fe83Ga17 alloy,the elongation and tensile strength of the(Fe83Ga17)99B1 alloy increased to 3.56% and 548 MPa,respectively.The element of B precipitated at grain boundaries in the form of Fe2B,resulted in that the grains refined and the grain boundary cohesion increased,so that granular fracture was inhibited.The element of Cr dissolved as Cr atoms in the matrix Fe83Ga17 alloy.The 2%(atom fraction) addition of Cr improved both the magnetostriction and room temperature mechanical properties of the Fe83Ga17 alloy.The maximum magnetostriction and elongation of the(Fe83Ga17)98Cr2 alloy were 7×10-5 and 0.6%,respectively.
Abstract: The effect of retrogression heating rate(340,57,and 4.3℃·min-1) on the microstructure,intergranular corrosion and stress corrosion resistance of aluminum alloy 7050 was investigated using electrical conductivity,intergranular corrosion and stress corrosion cracking testing and transmission electron microscopy(TEM).The results show that retrogression heating rate affects significantly the corrosion resistance of the alloy treated by retrogression and reaging process,and that under the condition of considering the comprehensive mechanical properties,the alloy has a better corrosion resistance at the medium rate.After retrogression and reaging at the retrogression heating rate of 57℃·min-1,the maximum intergranular corrosion depth of the alloy is 50 μm,i.e.Grade 3,which is shallower than those at the retrogression heating rates of 340℃·min-1 and 4.3℃·min-1.It is found that there are wider precipitate free zones and coarser discontinuous precipitates at grain boundaries.
Abstract: A numerical calculate model of alternating current(AC) power loss of clad materials with a rectangle section was presented.The effects of sectional form and configuration on the AC power loss of copper cladding aluminum(CCA) conductive flat bars were analyzed.The results indicate that when the sectional area of the bar is 600 mm2,the power loss coefficient increases with the width-to-thickness ratio of the bar increasing;when the area is 800 mm2 or 1 000 mm2,the coefficient increases firstly then decreases;and when the area is 1 200 mm2,the coefficient decreases and the tendency becomes weak with the width-to-thickness ratio increasing.As the thickness of the bar is 10 mm and the sectional area of the bar is in the range of 800 to 1 200 mm2,the AC power loss decreases with the rate of copper thickness of the bar's narrow side to broadside increasing in the range of 0.5 to 3.0.The effect of the rate of clad thickness on the AC power loss strengthens as the rate of the copper layer's area to the whole sectional area of the copper cladding aluminum bar increases in the range of 15% to 45%.When the direct current resistance per unit length and current capacity are the same as a copper flat bar's,the AC power loss of the copper cladding aluminum bar is less than that of the copper bar by adjusting the sectional form and configuration.
Abstract: Upper sinter cakes could be supported by the stands installed on the pallets and the load of the lower bed was reduced. As a result the permeability of the lower bed was improved and the sintering velocity increased, moreover the produetivity of sintering was boosted. The thermal stress of the stand was simulated during sintering process with ANSYS software. The results revealed that during sintering process the middle of the supporting surface and the middle and upper zone of the narrow surface of the stand were most easily damaged. During discharging, stress concentration occurred at the feet of the stand. When the thickness of the feet was over 40 mm the stand worked safely. The validity of simulation results were proved by the industrial trial of load reduction sintering.
Abstract: The calculation models of electromagnetic field in semisolid slurry preparation by annular electromagnetic stirring (A-EMS) were established, and the effects of stirring current, stirring frequency, crucible materials, cooler materials and gap width on the magnetic flux density in the slurry-making system were analyzed by ANSYS software with corresponding experimental verification. It is concluded that the simulation results are in good agreement with those obtained by experiment, verifying the reliability of the calculation models and the software algorithm. The electromagnetic force mainly distributed in the strring gap enhances the strring intensity of the A-EMS system. At the same gap width, the magnetic flux density increases with an increase in stirring current, but decreases with the stirring frequency increasing. The maximum magnetic flux density can be obtained by choosing both a stainless crucible and a graphite cooler. At the same current and frequency, the magnetic flux density increases as the stirring gap width decreases gradually. In comparison with conventional electromagnetic stirring, A-EMS can produce a finer and more uniform semi-solid structure with the average grain size decreased by 31% under the same stirring power.
Abstract: On the base of theoretical analysis on the medium-frequency heating of steel tubes, an electromagnetic-thermal coupling model of steel tubes was constructed with the Maxwell equations and the heat conduction equation. The electromagnetic and thermal fields of steel tubes were numerically simulated with Ansys software in consideration of the effect of the change in physical properties of materials with temperature on the heating process. The calculation results agree with the measured ones, for the surface temperature error of the heated workpieces was evaluated at 5.19%. The concept of induction heating penetration, which is used to divide the induction heating area and the heat transfer area during induction heating, was introduced. According to the simulation results, the induction heating penetration and the temperature distribution under different heating conditions were discussed. It is proved that the twin-coil heating mode is reasonable in distributing the temperature of the heated workpieees and assigning the heating efficiency and frequency.
Abstract: In order to improve the inner quality of slabs, a set of dynamic soft reduction models were developed, which include heat transfer, secondary cooling and roll gap control models, and the key parameters of soft reduction were optimized. The models were validated by shooting-pin tests and measuring the surface temperature of slabs. The measurement results agree with those calculated with the models, and the surface temperature fluctuation of slabs can be controlled in a narrower range when the casting speed changes. Production testing at different parameters of soft reduction was applied to optimize the percent reduction and reduction position by macrostructural examination and analyzing the center segregation. The best soft reduction parameters of this casting machine are that the solid ratio is 0.2 to 0.5 and the percent reduction is 1.2 mm· m-1.
Abstract: An intelligent control model of secondary cooling in continuous slab casting was presented to reduce the difference between actual temperature and target temperature at the surface of slabs during secondary cooling. The model dynamically sets the target temperature at the surface of slabs with support vector machine, forecasts the surface temperature of slabs with diagonal recurrent neural network, and dynamically controls and distributes the water flow of secondary cooling with T-S fuzzy recurrent neural network. Simulation calculation and field test were performed on the process of continuous slab casting in a steel plant. It is shown that the model integrates the problem of controlling the water flow of secondary cooling with the temperature state of slabs during the cooling process, can achieve the dynamic optimum control of secondary cooling and improve the quality of slabs.
Abstract: A mathematical model of contact heat transfer was build by the GW statistic contact model, and the results agree well with experimental data. By simplifying the rough interfaces, a model of radiation heat transfer between interfaces was constructed. The numerical results indicate that the effect of radiation heat transfer can not be neglected when the temperature of interfaces above 400 K. Nondimensional contact load has a larger influence on the conductive than the radiant conductivity, and for the non-contact area decreasing as the non-dimensional contact load increasing, the conductive conductivity increasing quickly and the radiant conductivity decreasing slowly. The influence of asperity slope on the equivalent radiation coefficient is the most important one among the geometric parameters of interfaces. At the same non-dimensional contact load, the smaller asperity slope the higher equivalent radiation coefficient. The numerical error-test of equivalent radiation coefficient shows that the order of the max relative error is 10-3. Within the range of this paper, the equivalent radiation coefficient is only the function of interfaces' character and contact load. It has nothing to do with the temperature and temperature difference of interfaces. The equivalent radiation coefficient is an appropriate parameter to express the radiation intensity in contact heat transfer.
Abstract: A multivariable system model was constructed with strip flatness and thickness as the control obieetives and with bending force and gauge as the main control variables for a combined shape and gauge system, and its mathematical expression was presented on the base of some industrial data in hot strip rolling process. Taking various kinds of secondary factors, perturbation and disturbance into consideration, a full order robust controller was given with the robust control toolbox in Matlab, and then a low-order controller was developed through balancing approximation in closed-loop design. Simulation results show the good performance of decoupling, anti-disturbance and anti-parameter-perturbation.
Abstract: A feature extraction method based on wavelet moment invariant and locality preserving projection (LPP) was presented and applied to the automatic recognition of plate surface defects. 3-level wavelet decomposition was performed on the surface images, details of the plate surface images were decomposed into components on several scales, and then the noise scattered in detail components of all the scales was reduced by wavelet shrinkage. Moment invariants were extracted from amplitude spectra of all the components, and then the feature vector composed by all the moment invariants was reduced from 77-demension to 8-dimension via LPP. At last, an AdaBoost classifier based on decision trees was constructed to classify the samples. Experimental results demonstrated that the feature extraction method presented in this paper was applicable to the classification of plate surface defects, and the classification rate was 91.60%.
Abstract: A single machine scheduling problem with family setup time was studied to solve the real-life scheduling problem in a steel wire factory. According to the requirements of the real problem, the maximum lateness was minimized. As the problem is NP-hard, a heuristic algorithm was proposed to solve the problem. The problem's characteristics were introduced into the algorithm to improve the search efficiency and running time. The proposed algorithm was tested both on randomly generated problems and on real-life scheduling problems from the workshop. The results show that the proposed algorithm can obtain a near optimal solution in a short time.
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
