Abstract: The critical sliding field technology was used to probe the sliding surface of a waste-dump slope. It is shown that the sliding surface of the slope is not a circular one. The reverse probing was carried out by using the expending method of critical sliding field, and the result show that both the safety factor and the optimum slope angle of waste-dump can be obtained.
Abstract: Water jet soil reaming parameters were analyzed based on the water jet theory and the soil mechanical theory. Some re-lationships between water-et parameters and soil parameters were established. The effects of water jet parameters and drill motion parameters on the soil reaming were investigated by an indoor test. The experimental results show that it is necessary to increase water jet power for enhancing the soil reaming effect. Increasing the water jet flow quantity has more obvious effect on the reaming than increasing the water jet pressure while the water jet impact force exceeds the soil critical breaking force. Reasonable matching the rotation speed and vertical speed of the drill pipe has more favorable effect on the soil reaming. It is feasible through engineering application that the water jet soil reaming technology is applied to making multi-ring type anchors in engineering, and the bearing capacity of the anchors is significantly improved.
Abstract: The dynamic characteristics of multi-span non-uniform continuous beams were analyzed by the Bernoulli-Euler beam theory. Based on the basic principle of modal perturbation, the analytical mode functions of uniform continuous beams were used to transfer the differential vibration equation of non-uniform continuous beams to a set of algebraic equations. In the method, the dynamic characteristics of the beams with complicated section types can be solved effectively, whether the section function is continuous or not. The numerical results of two examples show that the method is simple, practicable and has good precision.
Abstract: Three methods were analyzed to reduce the silicon content of hot metal in theory:controlling silicon resource, decreasing the drip zone's altitude, and increasing the oxidation of slag in hearth. Some factors to influence the silicon content of hot metal were proposed on the basis of the experiment in the lab:increasing the binary basicity is favorable to desiliconization; the oxide in slag debases the silicon activity and is of great advantage to desiliconization; Al2O3 and SiO2 are disadvantageous to desiliconization; the volatilization content of SiO2 in coke increases with increasing smelting temperature, leading to increase the silicon content of hot metal; the silicon content of hot metal increases with increasing the drip zone's altitude. The measures of reducing the silicon content of hot metal were applied in JIAN-Long Iron and Steel Company in Tangshan according to the test results. The result of reducing the silicon content of hot metal was obvious, and the mass fraction of silicon in molten iron was reduced to 0.40% from 0.55%.
Abstract: A new kind of alkaline paint stripper was prepared for tinplate. The mass concentrations of sodium hydroxide, cetyhrimethyl ammonium bromide (CTMAB), sodium citrate and glycerin in the aqueous stripper are 90-100·L-1, 10·L-1, 10·L-1 and 10·L-1, respectively. The paint could totally be removed from tinplate when it was placed in the stripper at 95℃ for about 20 rain, There was no notable corrosion happened, and the recovery of tin was above 99%. The mechanism of paint removal was discussed. The result shows that the stripper can be reused, and 10 mL of the stripper can remove 200 cm2 of paint layer on tinplate. It is high-performance, nontoxic and safe for environment.
Abstract: Microstructure evolution in eutectoid steel during warm deformation in the temperature range from 600 to 700℃ was investigated by simulating hot compression test, SEM and thermomagnetic measurement. The effects of deformation and subsequent annealing on the spheroidizing of pearlite, refining of microstructure and dissolution of cementite were studied. The experimental resuits indicated that during warm deformation of eutectoid steel, pearlite lamellas fractured, cementite gradually spheroidized, and dynamic recovery and recrystallization of ferrite took place with fine dispersive cementite particles being precipitated. An increase in deformation temperature enhanced the above processes. Following annealing, the microstructure consisting of submicron-scale equiaxed ferritic grains and dispersive cementite particles became more homogeneous. Partial dissolution and re-precipitation of cementite during warm deformation were confirmed.
Abstract: The effects of intercritical annealing temperature on the phase transformation, retained austenite characters and mechanical properties of 0.15C-1.5Mn-1.5Al TRIP-aided cold-rolled steel sheets were investigated by means of dilatometric measurements, heat treatment testing, tensile testing and X-ray diffraction analysis. Similar transformation processes were found at different intercritical annealing temperatures, while the austenite fraction increases and its carbon content decreases with increasing the intercritial annealing temperature; intercritical annealing temperature affects the mechanical properties of the TRIP steel and the volume fraction and carbon content of retained austenite. When the temperature is 820℃, the specimens have excellent mechanical properties with the tensile strength and elongation product of 25 400 MPa·%, and the volume fraction and carbon content of retained austenite reach the highest values of 14% and 1.36%, respectively. This retained austenite shows fine mechanical stability and gradually transforms to martensite during deformation, showing a higher instantaneous work-hardening index n than other specimens.
Abstract: Two kinds of corrosion polarization diagrams were used to describe the corrosion kinetics of alloys. They have different coordinate systems. One is the coordinate system where the coordinates are the potential and the current on the unit area of alloy surface, the other is the coordinate system where the coordinates are the potential and the true anodic and cathodic current density. The former is called the apparent corrosion polarization diagram of alloys, and the latter is called the true corrosion polarization diagram of alloys. The effect of cathode-to-anode area ratio on the corrosion kinetics of an alloy was studied under activation polarization control. Combining the apparent with true polarization diagram, not only the corrosion rate of the alloy can be expressed directly, but also the mechanism of the corrosion cell can be analyzed clearly.
Abstract: TiFe alloy was prepared directly by electrolytic reduction from the mixture of TiO2 and Fe2O3 in molten CaCl2 at 1173 K and 3.1 V. The reduced product was TiFe with an oxygen content of 0.43% in mass fraction after electrolyzing for 10 h. The whole electrolysis process, roughly, includes two periods:the reduction of Fe element and the forming of TiFe. In the initial stage of electrolysis, Fe element is reduced first prior to titanium and CaTiO3 is formed. Then the external cathode is reduced to TiFe. Meanwhile, the cathode is layered:the external loose layer mainly contains TiFe and the inner layer, which is much harder and more compact, chiefly consists of Fe and CaTiO3. Electrochemical behavior test shows that the discharge capacity of TiFe alloy produced by electrolysis without activation is about 33 mA·h·g-1 and TiFe alloy by this performance is better than those prepared by other methods.
Abstract: The microstructure and mechanical properties of an Al-Cu-Mg-Ag alloy aged at 165℃ were investigated, and the underage (165℃ × 2 h) samples were subjected to thermal exposure at 150, 200, 250 and 300℃ for 0 to 1000 h. The results indicate that at the exposure temperature of 150℃, the residual strength of underage samples appears to increase first and then decrease, and the peaking strength is obtained when lasting for 100 h. The change in elongation of the samples has the same tendency as the change in residual strength. Compared with underage condition, the mechanical properties of the samples have no obvious variation after the 150℃/1000 h exposure, and thus the alloy represents a superior heat-resistance ability. With prolonging exposure time and increasing temperature, the residual strength of the samples appears to decrease and the elongation appears to increase at 200, 250, and 300℃. The residual strength of the samples obviously decrease at the exposure temperature of 300℃, and the tensile strength of the samples after the 10 h exposure is 272.5 MPa decreasing to 114.5 MPa after the 100 h exposure. At all examined temperatures the Ω plate thickening shows a linear dependence on time. With increasing exposure temperature, the Ω plate thickening kinetics greatly increases and the precipitation free zones broaden in grain boundary.
Abstract: A Ce conversion coating, which is non-toxic and non-pollution, was prepared by chemical dipping immersion treatment on graphite fibers reinforee aluminum (Gr/Al) eoraposite surface. It is shown that the graphite fiber and aluminum alloy surfaces both are coated by the Ce conversion coating, and the microstructure of the coating is dried-mud-like. Energy dispersive spectroscopy (EDS) indicates that the major elements distributing on the coating are Al, O, C, Si, Ce, and Mg, and the mass fraction of Ce is 14.44wt% after coating for 30 rain but increases to 47.48wt% after coating for 120 min. The formation meehanism of coating mierocracks was put forward. The micro-cathodic formation mechanism can explain the characters of the coatings. The Ce conversion coating becomes a barrier of O2 diffusion and electron transmitting, and oxygen absorption and hydrogen separation were both inhibited.
Abstract: Aluminum alloy/aluminum/steel and aluminum alloy/steel/steel cladding plates were exploded by different explosive welding technologies. The bonded interface's configuration was observed and analyzed, and the wave parameters were measured by optical microscope. The results show that the wave configuration of the bonded interface depends on the explosive welding technology and material properties. A line-straight bonded interface formed when the properties of the base plate and flyer plate were greatly different. However, a regular sine wave shape was easily generated when the base plate and flyer plate were the same or their properties were similar. The wave length and the wave amplitude become bigger with increasing explosive density.
Abstract: A thermodynamic simulation program for Nb powder production process by hydrogen reduction of NbCl5 in argon was developed by using SimuSage Software, which is a component library used in the developing of process simulation. The effects of the key parameters such as evaporation temperature, loading gas amount (Ar(g)), reduction temperature, He (g) amount and collection temperature were studied by the simulation program. The results show that the evaporation rate of NbCl5 (s) and the content of NbCls(g) in gas are dependent upon the evaporation temperature and the amount of Ar(g) used. To get Nb(s) as the unique solid product, a minimum H2 (g) amount of 20 mol per mol NbCls is needed when the reduction temperature is 1000℃. High temperature of collection is helpful to the purity of the solid Nb powder product.
Abstract: Spark plasma sintering (SPS) process was used to prepare superfine WC-10Co cemented carbides. The effects of sintering temperature and sintering atmosphere on the microstructure and properties of WC-Co cemented carbides were investigated. The results show that the density of the compacts increases with increasing sintering temperature. However the composition of the compacts is different from that of the starting powders because of the evaporation of Co, and the evaporation rate of Co increases with the increase in sintering temperature and the decrease in atmosphere pressure. It is found that the composition of the compacts can be very close to that of the starting powders by increasing the atmosphere pressure. The mass fraction of Co in the compacts sintered at 1 250℃ for 5min under 30MPa in the argon atmosphere of 200Pa is 10.02%, and the density and hardness are 14.62g·cm-3 and HRA 92.4, respectively.
Abstract: A cermet lined steel pipe was prepared by the self-propagating high-temperature synthesis (SHS) centrifugal process. In the process, Fe203, WO3, Al and C were used as the staring mixture in order to synthesize a cermet lined coating after the mixture ignited and combusted. The phases in the synthesized coating were examined by X-ray diffraction (XRD). The of the coating and the substrate/coating bonding interface and the distribution of elements adjacent to the interface were analyzed by scanning electron microscopy (SEM) and energy dispersion spectroscope (EDS). The hardness of the coating was measured. The resuits show that a metallurgical bonding interface is formed between the coating and the substrate pipe. The coating is mainly composed of Fe3W3C, and there is a little WC, W2C, Fe3C and Fe in the coating. The phases in the coating possess a gradient distribution along the depth of the coating. The grains near the substrate are fine but those far from the substrate are coarse dendrite crystals. The microhardness of the coating is 13,50±1.6 GPa, which is 7-8 times higher than that of the substrate.
Abstract: Dendritic growth in a binary mixture with imposed flow was investigated. When the Schmidt number was large, the asymptotic solution for the steady state was obtained by using the asymptotic analysis method. The zeroth-order and the first-order solutions are similar for the temperature and concentration fields. The shape of the dendrite is paraboloid of revolution on which there are small waves. The strength of external flow has a significant effect on the Peclet number of dendritic growth, the tip radius of den-drite and the tip growth velocity. For the given undercooling, the temperature at the dendritic tip or in front of the dendrite decreases with increasing flow, but the solute concentration increases.
Abstract: Under the presence of a constant magnetic field (0.2T), conducting polyaniline (PAn) was synthesized by microemulsion polymerization with sodium dodecylbenzenesulfonate (SDBS) as emulsifier, ammonium peroxydisulfate (APS) as oxidant and sulfosalicylic acid (SSA) as doping agent. The properties and structure of PAn were characterized by infrared spectrum, X-ray diffraction, particle-size analysis and conductivity measurement. The results indicate that the conductivity, doping ratio and corrosive potential of PAn are improved under the presence of magnetic filed, and no effect of magnetic field on the basic structural units of PAn is observed. Compared with the PAn synthesized under the absence of magnetic field, the PAn synthesized under the presence of magnetic field has a higher crystaUinity and obvious microscopic orientation structure, the polymerization time decreases from 3 to 2 h, the concentration of doped acid (CSSA) decreases from 0.4 to 0.3 mol·L-1, the mole ratio of SDBS and aniline monomer (nSDBS/nAn) decreases from 0.6 to 0.45, and the conductivity of PAn increases from 6.42S·cm-1 to 10.01 S·cm-1.
Abstract: The components and microstructure of BF dust (dust and sludge) in Baosteel BF at large pulverized coal injection (PCI) rate were investigated by microscopic analysis. The area percentages of unconsumed pulverized coal and coke particles were obtained at different PCI rates. The effect of large PCI rate on the mass fraction of carbon and the unconsumed pulverized coal ratio in BF dust was analyzed. The amounts of unconsumed pulverized coal and coke particles as well as the utilization rate of pulverized coal were tested in BF at large PCI rate. The experimental results showed that with increasing PCI rate the amount of BF dust increased, but at large PCI rate it fluctuated. With the increase in coal injection rate the amounts of carbon and unconsumed pulverized coal in BF dust increased, but the amount of unconsumed coke particles in BF dust hardly changed and kept at about 3 kg·t-1. It is indicated that the quality of coke in Baosteel BF is very good.
Abstract: A micro physical model to describe the thermal radiation scattering on the interface between two homogeneous media was established, the spacious profiles of electric intensity at any incident angle and the reflection/refraction angles were numerically simulated. The comparison of numerical results with experimental ones indicates that the simulation is in good agreement with the classic principles, which indicate that this model can explain the micro-mechanism of reflection and refraction on the interface between two media.
Abstract: To overcome some shortcomings in current vector control (CVC) and basic direct torque control, a new speed and torque control strategy based on direct flux control (DFC) was presented. In this method, the flux and torque are controlled through directly controlling the trajectory of stator flux vector. It has some advantages such as fast dynamic response, constant switching frequency, reduced torque and flux ripple. The necessary condition for direct flux control to a permanent magnet synchronous motor (PMSM) was put forward. Simulation results show that the strategy not only operates well in the constant torque range, but also in the flux weakening range, and it improves fast dynamic response of speed and torque control over wide speed operation, better than the traditional current vector control.
Abstract: Aiming at maximizing the utilization of orders fulfillment and minimizing matching cost, a constraint satisfaction model was established for customer orders and the inventory matching problem of hot rolling strips in modern steel enterprise, considering steel specification, weight, grade, production process, and other constraints. Based on analyzing the characteristics of the problem and the matching objects, a matching loss matrix was introduced regarding as the loss penalty of the different matching result of orders and inventory surplus. Taking advantage of the complication of the issue, a heuristic algorithm, which is based on variable selection and value selection, was presented to solve the model in sequence. Numerical experiment was given to validate the proposed algorithm.
Abstract: To improve the trust evaluation accuracy of the DyTrust model, solve the problem of rough granularity of the trust model, and deal with the trust evaluation problems caused by individual experience, based on the DyTrust model, an improved algorithm of trust evaluation was presented after using an experiential factor and the particular services of nodes. Compared with the DyTrust model, the improved model has the advantages of crisp granularity, high accuracy, reflecting the personalization of nodes, enhancing the feedback trust value, and high scalability.
Abstract: The state equation of an typical affine nonlinear system was solved with the ordinary differential equation theory. By utilizing the expansion expression of equilibrium point of the system, the homogeneous equation's solution was obtained, and then the nonlinear differential equation was equivalent to its nonlinear Volterra's integral equation of the second kind by the constant variation method. Any order approximate solution of the equation was presented, and its convergence was mathematically proved by the successive approximation method.
Abstract: Attribute reduction of rough sets is an NP hard problem, but there is not a popular efficient algorithm presently. The attribute union concept based on the set theory and the attribute reduced algorithm based on this concept were presented. The algorithm translates the attribute reduction to find the attribute union, reducing the number of scanning the decision table and improving the reduced efficiency. The scanning strategy from bottom to top and with width priority can insure to find the minimal reduction. Also, an example was presented to describe the algorithm.
Abstract: Building up a high-quality, expandable, complete, free-discardable, free-of-repetition and free-of-abnormal-ambiguity multi-language semantic unit knowledge base for a multi-language machine translation system was discussed. In the process of buildup, the type feature classification method was adopted o effectively reduce the calculation complexity, make the calculation for repetition removal reduced by half, and reduce the trash-removal calculation to O (βN), where N is the scale of the semantic unit knowledge base, β is bounded, β< C and C is a constant. All algorithms can be concurrently realized on a multi-core processor in constant efficiency. Furthermore, the reecomposition of a semantic unit and the expansion methods for the semantic unit knowledge base in case of natural language type increase were also discussed. This knowledge base can be used not only for the multi-language machine translation system but also as the basic knowledge base for natural language understanding and processing.
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
