Abstract: The relation of drilling cuttings weight to ground pressure and gas pressure was investigated by in-situ experiment on the 2124 fully mechanized coal mining face of Sanhui Mine in Chongqing Tianfu Coal Industry Co.,Ltd.The distribution of ground pressure after drilling was obtained as the following: the stress-relief zone width of about 5 m,the location of the plastic zone at 5 to 11 m,the location of the elastic zone at 11 to 20 m,and the location of the original stress zone beyond 20 m.The drilling cuttings weight linearly increased before the peak ground pressure and decreased after it under the premise of drilling in strict accordance with the operating rules.Based on the theoretical analysis of ground pressure and gas pressure on the longwall mining face,a positive relation of drilling cuttings weight to ground pressure and gas pressure was deduced.The drilling cuttings weight positively changed with ground pressure at the fixed gas pressure or with gas pressure at the fixed ground pressure.
Abstract: A discrete mathematical model based on random linear Kalman fihering is introduced to eliminate random disturbance noise in the process of GPS slope deformation monitoring and to improve the validity of monitoring data. On the base of GPS slope monitoring data in Shuichang Iron Mine, the filtering value of deformation and the velocity of displacement at each point in each stage can be calculated with the mathematical model and the slope deformation at each point in the next stage can be estimated and predicted. It is proved with an example that the deformation obtained by Kalman filtering is more approximate to the real slope deformation.
Abstract: According to the characteristics of a high and steep slope in Changba Lead-zinc Open-pit Mine,a slope monitoring project was selected,which is chiefly by GPS,secondly by leveling instruments and crack instruments.Designing and construction of the monitoring system were introduced in detail.Monitoring data of the 1 500 m step of the north wall slope were taken for example to analyze the deformation law,and synthetic monitoring results of the north wall slope were evaluated.The results show that the stability of the north wall slope between B03 and B06 is the poorest,its maximum displacement reached 231.1 mm in nearly 600 d,and slip rock mass may exist in the segment slope.The displacement rate curves display an obvious S-shape,and the convex segment shows an acceleration deformation stage by rainfall in rainy season.Accumulated deformation of cracks can be divided into three stages: early relative stable stage,middle deformation triggering stage and the third stage stable deformation duration.Monitoring data indicate that the displacement of the middle 1 500 m step slope is greater than any others,and its stability is the poorest.The application effect of the monitoring system is significantly,which is one of important methods for displacement monitoring of high and steep slopes.
Abstract: In the process of blast furnace bell-less top charging,it is difficult for operators to directly observe the burden surface profile and burden trajectory.Based on the principle of optics,a polar coordinate laser grid measurement technology is proposed to measure the burden surface and burden trajectory.Dual CCD stereoscopic vision calibration with high precision is introduced to create the detailed computer images of the burden trajectory with a boundary operator,acquire information about the burden trajectory in charging,and reconstruct the process of blast furnace bell-less top charging.
Abstract: A two-parameter model for estimating the standard entropy of binary intermetallics was developed based on the analysis of existing thermodynamic data.The model can estimate the standard entropy of binary intermetallics formed by simple metals,involving the multi-systems of Fe,Si,Nb,Ti,Cu,Co,Mg,etc.The standard entropies of 132 intermetallics,such as AlCa,AlCo,CrNi,FeTi,FeSi,FeNb and MoSi,were estimated.It is found that the average error of standard entropy is about 4.86 J·mol-1·K-1 and the standard deviation is 6.24 J·mol-1·K-1.The accuracy of standard entropy estimated by the two-parameter model is higher than that estimated by the ion binding model.
Abstract: Dual phase steel with 63.8% of ferrite grains and 53% of martensite grains in the size distribution of 0.5 to 1 μm was produced through adopting the initial microstructure of ferrite,bainite and martensite in combination with the cold rolling and continuous annealing process.The grain refining mechanism of vanadium-containing dual phase steel based on the initial microstructure of ferrite,martensite and bainite was investigated.It is found that the refining theory mainly has three aspects:(1) microstructure refinement by deformation including hot rolling and cold rolling for the initial microstructure of ferrite,martensite and bainite;(2) recrystallization and rapid austenitization of the as-cold rolled microstructure;and(3) vanadium precipitation preventing austenite from growing up.
Abstract: Early-stage formation of Cu-rich nano-clusters in thermal aging nuclear reactor model pressure vessel steel quenched and tempered was investigated by atom probe tomography(APT).After the initial heat treatment at 880 ℃ for 0.5 h and water quenching,the materials were tempered for 10 h at 660 ℃ and air cooled.Cu-rich nano-clusters were observed in the samples aged at 400 ℃ for 1 000 h.The change in composition of the steel in the early-stage of precipitation of Cu-rich nano-clusters was studied by the maximum separation envelope method(MSEM).Cu nanoclusters are observed to form from high nickel regions.The Cu concentration increases and the Ni concentration decreases at the central cores with increasing Cu atoms congregation.Ni and Mn atoms aggregation on the exterior side of the cluster/matrix interface is also evident.Based on experimental results,the reason that Ni and P can increase the sensitivity to neutron irradiation embrittlement of the nuclear reactor pressure vessel steel is discussed.
Abstract: The macrosegregation of C,P,S,Cu,Si and Mn in cast ingots of weather-resisting steel was studied by applying the technology of original position statistic distribution analysis(OPA),and the effect of rare earth elements(RE) on the macrosegregation in the steel was analyzed.The results showed that under the condition of the equiaxial crystal rate of 30% to 40% and the overheating temperature of 20 ℃ in the ingot,there was serious macrosegregation of C,S,P and Cu in the steel.C and S present center positive segregation,P and Cu the center negative segregation,and P and Cu the inverse segregation,while the solute distributions of Si and Mn were more uniform.The segregated zone of each element was of exactly the same.The solid solubility of RE in the steel were 10-5 to 10-4,and the soluted RE could refine dendrites and increase the equiaxial crystal rate.The macrosegregation of C,P,S and Cu was improved obviously by adding RE of 0.38% to 0.55% into the steel.
Abstract: To reduce the susceptibility of crevice corrosion of 2024 aluminum alloy in seawater,the effect of LaCl3 on the crevice corrosion behaviour of the alloy was investigated by immersion,potentiodynamic polarization and electrochemical impedance spectroscopy.The micrographs of corrosion product films formed on the inside and outside of crevice samples were observed by atomic force microscopy.The results show that when the concentration of LaCl3 in seawater is in excess of 2.0 g·L-1,the crevice corrosion may be inhibited obviously.It is because that the cathodic reaction rate of crevices is decreased and the oxygen concentration difference between the inside and outside of crevices is reduced.Moreover,the uniform corrosion product film formed on the inside and outside of crevices blocks the aggressiveness of Cl-.The initiation and propagation of crevice corrosion are restrained by these factors,and thus the crevice corrosion resistance of 2024 aluminium alloy in seawater is improved.
Abstract: In order to deal with nickel materials which contain high lead,experimental investigations were performed to remove deeply lead from anodic electrolyte.By analyzing the relationship of Pb2+ concentration in electrolyte and lead content in electrolytic nickel,the mechanism of lead removal by coprecipitation,and the effects of Cl- and Fe3+ on the results of lead removal,some optimum technological parameters were determined for deep lead removal by coprecipitation: the coefficient of adding barium chloride is 150,the temperature of lead removal is 55 ℃,the time of lead removal by stirring and the time of adding barium chloride solution by spraying are 60 min and 21 min respectively,and the mass concentration of flocculant is kept constant at 2.5 g·L-1. It is shown that lead can be removed by coprecipitation with barium chloride,the mass concentration of Pb2+ is not more than 0.000 3 g·L-1 in lead removal electrolyte,and the mass fraction of nickel in slag is less than 4%,which meet the need of producing electrolytic nickel for electrolyte composition.The enlarged experiments prove that the technological parameters derived from the laboratory experimenters are reliable and the process has been applied to industrial production successfully.
Abstract: Compression fatigue experiments of WC-12Co cemented carbide were carried out on Gleeble 1500 under different thermomechanical conditions.The Vickers hardness of the alloy was tested,the microstructures were observed by SEM and TEM,and the deform mechanism was discussed.It is shown that with increasing experimental temperature and load,the continuity of WC skelectons is broken down,leading to the decreasing in hardness of WC-12Co alloy.The deform mechanism of WC-12Co alloy is that the alloy's plastic ability is offered by the slipping of dislocations in WC phase and the binder's martensitic transformation at low deformation temperature and stress.With the deformation temperature and stress increasing,the further deformation ability is offered by the movement of stacking faults in WC and the slipping of WC/WC interfaces.
Abstract: The effects of Pt/YSZ electrode sintering temperature on its characteristics were studied by AC impedance,cyclic voltammetry,chronoamperometry,and SEM observation.The result indicates that as the sintering temperature increases,the activation energy of the electrode process decreases,both the electrode total resistance and response time decrease first and then increase.While the sintering temperature is below or equal 1 100 ℃,a large quantity of oxygen atoms are adsorbed on the Pt electrode surface,Pt oxide will be found due to the site exchange reactions of the adsorbed oxygen atoms and Pt atoms,and the activation energy of the electrode process is from 177 to 230 kJ·mol-1;as the sintering temperature is above 1 100 ℃,Pt oxide probably existed in the electrode system decomposes completely,and the activation energy of the electrode process is from 107 to 172 kJ·mol-1.The electrode sintered at temperatures of 1 000 to 1 100 ℃ has the least total resistance,the shortest response time of charge transfer,and the highest activity.
Abstract: The attrition of two different fluid catalytic cracking(FCC) catalysts was investigated by laboratory-scale jet-cup test.The mechanical properties of the catalyst particles were evaluated by nano-indentation test and conventional microhardness test based on the nano-and the micro-length scales.The attrition mechanism of the catalyst particles in a gas fluidized bed was analyzed in terms of indentation testing,morphology characterization,attrition rate evaluation and particle size distribution analysis.The influences of material characteristic properties on the particle attrition were mainly discussed.The results show that the attrition of the catalyst particles follows Gwyn's kinetic model and the difference of attrition mechanisms of various catalyst particles can be categorized with the parameters of the Gwyn equation.
Abstract: The effect of polyethylenimine(PEI) concentration on the morphology,wire density and size of ZnO nanowire arrays was systematically studied by X-ray diffraction(XRD),transmission electron microscopy(TEM) and scanning electron microscope(SEM).The photovoltaic properties of ZnO nanowire array films were also investigated.It is demonstrated that,for a ZnO nanowire array film obtained from 7.3 mmol·L-1 PEI,an energy conversion efficiency of about 0.66% was obtained,which is the highest for ZnO nanowire array films prepared with different PEI concentrations from 3.2 mmol·L-1 to 9.3 mmol·L-1.
Abstract: The hot extrusion process of GH4169 superalloy tubes was simulated by using Msc.Superform software with the true flow stress-true strain curves of GH4169 alloy at different temperatures and strain rates.The effects of technical parameters on the extrusion processing were systematically analyzed to optimize the extrusion process.The results show that high quality products can be expected using forward extrusion.The optimal parameters are the extrusion speed of 100 and 300 mm·s-1,the die angle of 20 to 30°,the billet preheating temperature of 1 040 to 1 050 ℃ and a better lubrication condition.
Abstract: In order to carry out the practical application of wire drawing using ultrasonic vibration,in consideration of different effects caused by different types of ultrasonic vibration,a set of experimental system for wire drawing with orthogonal composite ultrasonic vibration was designed and built,which was composed of an ultrasonic power,an ultrasonic vibrating system,a die and a drawing machine,etc.The operating mechanism of wire drawing using ultrasonic was analyzed by simulation through the finite element method.Through a series of drawing experiments of brass wires,the effects of longitudinal,radial and orthogonal composite ultrasonic vibration on the drawing force and surface quality of wires were discussed during actual wire drawing process.The experimental result shows that when the ultrasonic vibration amplitude is enough,the action effect of orthogonal composite ultrasonic vibration is the best,and it can effectively prolong the tensile-regulation cycle of wire drawing machines more than three times.Ultrasonic vibration can reduce uneven deformation of wires and make the drawing tend to be more stable.When the drawing speed is 980 mm·s-1,the reduction in drawing force caused by ultrasonic vibration is about 30% and the surface quality is improved.
Abstract: The effects of RuCl3 solution concentration,pH value,and soaking time on the catalyst performance were studied during the preparation of Ru-Ni foam catalysts.The relationship between exothermic reaction and system temperature was also discussed.It was indicated that the average hydrogen generation rate of the catalyst prepared with 0.2 g of Ni foam in 0.025 mol·L-1 RuCl3 solution with pH values of 5 to 7 for a soaking time of 25 h was 600 mL·min-1 in the solution of 15% NaBH4 and 3% NaOH.When the catalyst was immersed in 20 mL of NaBH4 solution,the energy released form hydrolyzation could make the system temperature increase to 80 ℃.
Abstract: CO deep removal was investigated by combining preferential methanation and preferential oxidation(M-O method).In the M-O method,CO of about 1% in reformate from a water gas shift(WGS) reactor is reduced to about 0.1% in the first stage of preferential methanation,then further reduced to below 10×10-6 in the second stage of preferential oxidation.The results show that in comparison of the M-M method(a method of CO deep removal with two-stage preferential methanation) the M-O method could be operated with a wider temperature range and a higher gas hourly space velocity at a lower temperature,and has almost the same thermal efficiency.In the other hand,although a reaction system of the M-M method is simpler,a reaction reactor of the M-O method could be more compact in comparison.In addition,a high-speed preferential oxidation step set at the outlet of the second stage in the M-M method or M-O method was proposed to remove CO to below 1×10-6,which helps to enhance the stability of proton exchange membrane fuel cells under long time continuous running.
Abstract: An optimization approach,combining a simplified conjugate-gradient method(inverse problem solver) and a three-dimensional,two-phase and non-isothermal fuel cell model(direct problem solver),was developed to determine the key geometric parameters of a proton exchange membrane fuel cell.In this approach,with channel height as the searching variable(optimized object) and the reciprocal of cell output power density as the objective function,the optimum channel height(optimized design variable) was derived from searching the minimum of the objective function.The results show that for the optimized serpentine design,except the outlet channel being diverging,the other channels should be tapered.The cell performance is,meanwhile,improved by 11.9% compared to the convectional serpentine flow field under the same operating conditions.A detailed investigation of local transport characteristics reveals that the tapered channel design enhances sub-rib convection,leading to more oxygen transport over the cell and more effective liquid water removal out of the cell;however,the diverging outlet channel can provide relatively proper sub-rib convection to prevent reactants from "short-circuit",which means that reactants directly flow out of the cell and thus results in reactant waste.
Abstract: Based on the special spatial structure of a rotary tube expanding mill,a conditional extremum method was used to determine the position of aperture points on the roller surface,to resolve the space coordinates of aperture points,and to construct a model for calculating the opening of holes in the formation zone of rotary tube expanding.The cone angle in the smoothing zone of plugs suitable for the opening of pass was calculated with the model.The calculation results are in agreement with the actual parameters of production.
Abstract: In order to give full play to the crown control ability of CVC work rolls and improve the profile quality of strips,in-situ tracing and testing the shifting position of CVC work rolls in a CSP production line were conducted.The result indicated different shifting characteristics of CVC work rolls for different stands,which reflected their inappropriate crown control ability.Based on the research on different profile control characteristics for different stands,the influence of the wear contour of work rolls on the crown control ability,the different control effects of CVC work rolls in different stands,and the high reduction during CSP hot rolling,a principle was proposed that the crown control ability of CVC work rolls should decrease from F1 stand to F7 stand during CSP hot rolling,and three different shifting strategies,normal distribution,parabola distribution and to-and-fro shifting,for CVC work rolls were presented.
Abstract: 3-dimension modeling and numerical simulation for nozzle arrangement of a controlled cooling equipment was carried out by the Fluent finite element simulation software to obtain a uniform axial temperature field.The effects of some controlled cooling parameters,such as nozzle diameter,nozzle number,nozzle rows,the inlet speed and direction of nozzles,on the cooling uniformity of the pipe wall were analyzed.The results show that the nozzle diameter,the layout,and the inlet direction of nozzles have relatively great influence on the cooling uniformity of the pipe wall,but the inlet velocity of nozzles affects only the cooling rate and has little or no effect on the cooling uniformity of the pipe wall.
Abstract: A control method based on generalized predictive control(GPC) was proposed for a multivariable coupling system,Error weights could be self-regulated in order to reduce interactions in the system and improve dynamic performances of coupling loops.Compared with the conventional multivariable generalized predictive,the proposed method is characteristic of simplicity and small computational burden.The algorithm was applied to an auto-shape control and auto-gauge control system(ASC-AGC),and simulation results demonstrate its efficiency and correctness.
Abstract: The practical engineering of reinforced soil retaining walls in Jiehe Overpass,which locates on No.104 National Highway in Shandong Province of China,was taken as an example to determine the reasonable range interval of a prestressed anchor layout on the base of limited test data.Firstly,a nonlinear functional relation between the optimization parameters and optimization object was fitted by the least squares support vector machine(LSSVM).Then,the model was trained through data samples from in-situ test.Finally,the model was optimized by the artificial fish swarm algorithm(AFSA) to get the reasonable range interval,and the same time the rationality of optimization parameters was verified by monitoring the reinforcement effect of post-construction.The results show that this model is reasonable and feasible,with the characteristic of easily modeling,rapid convergence rate and high inversion accuracy.
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
