Abstract: In order to partition water conservation areas in the upper Yangtze River, inner and external indexes in an ecosystem were used to constructed a delimitation index system, and the key water conservation areas were delimitated by the delimitation model in combination with the ArcGIS Spatial Analyst. Based on the actual situation of research areas, a multi-level and multi-structure index system for eco-security assessment was built with the PSR (pressure-state-response) model framework. Eco-security assessment of the key water conservation areas was carried out by a combined application of AHP (analytic hierarchy process), vector similarity and principal component projection method. Gray correlation was added in finding out the main influencing factors on regional eco-security. The results show that these main factors are rainfall, increase rate of GDP, effective utilization rate of water resources, vegetation coverage, and water environmental quality.
Abstract: The deformation and failure law of a high steep slope during transformation from deep open-pit to underground mining using similar material physical models and numerical simulation was researched with Daye Iron Mine as an example. The similar material physical model was monitored with stress sensors, dial-gauge displacement sensors, and close-range photogrammetry methods to obtain the failure and stress-strain characteristics. Systematic analysis was made on displacement and crack failure of surrounding rock to discover the basic deformation and failure law of the high steep slope. The stress distributions, surface subsidence, and plastic zones predicted by a finite-difference numerical model were compared with those measured from the similar material model experiment. The results indicate that the maximum vertical settlement of the high steep slope is 28.2 mm. The extent of damage and the plastic zone in- crease with the mining depth increasing. The shear failure of the rock mass mainly appears at the foot of the two sides slopes. The combination of similar modeling and numerical modeling is a good solution for research on the basic characteristics of rock mass deformation and failure of high-steep slopes during transformation from deep open-pit to underground mining.
Abstract: The characters of gas seepage in coalfield outcrop and the thermal dynamical system of outcrop spontaneous combustion were analyzed. A model coupling seepage with thermal dynamics for spontaneous combustion of coalfield outcrop was set up. The calculation equation of volatile output during coal spontaneous combustion was deduced. One coal fire in Xinjiang Uygur Autonomous Region of China was selected as the simulated object by the seepage-thermal dynamic model. It is shown that when spontaneous combustion of coal outcrop results from the mining, the combustion center centralizes near the roof and spreads to the outcrop direction quickly. The high-temperature region locates below the roof and the temperature gradient out of the combustion area is not obvious. Gases produced by coal spontaneous combustion mainly flow in the downstream of the spontaneous combustion area and the combusted gases only exists a small region on the upstream of the combustion area. The higher temperature distribution accords with the seepage scope of spontaneous combustion gases. Whereas, coal spontaneous combustion accelerates gas seepage in the coal and rock medium and is helpful to development of spontaneous combustion. At last, based on the simulated results, some measures on the coalfield fire location, fire control and fire monitor were analyzed.
Abstract: To study the different permeability characteristics of rock, transient permeability tests of limestone and diorite were carried out. The permeability evolution and the relation between pore pressure and time of rock specimens during the complete stress-strain course were investigated. The strain-permeability equations of rock specimens during the deformation and failure course were set up. Finally, the penetration mechanism of two types of rocks was analyzed. The result shows that the phenomenon of the sudden jump of permeability occurs at the peak strength and keeps very low unchanged permeability before the peak strength for diorite. But limestone's permeability gradually increases with increasing deformation before and after the peak strength. The fitted equations for the strain-permeability curve more deeply describe the permeability characteristics in compressive failure. The relation between pore pressure and time is quartic polynomial with one unknown. The rock permeability has relations with the stress state and the internal structure and the mechanical properties of rock.
Abstract: The change in exhaust composition (such as O2, CO2, SO2 and NO) at different bed depths in sintering process was studied. The results show that with the sintering process proceeding, the quantity of combustion solid fuel increases, therefore the content of O2 decreases and the content of CO2 increases. As SO2 is absorbed by the sinter bed and NO is reduced by CO in the combustion zone, the contents of SO2 and NO increase slowly. Near the burning through point, the absorption of SO2 by the sintering bed disappears and the decomposability of SO2 strengthens, leading to the rapid increase of SO2 content. With the bed depth increasing, the ratio of solid fuel declines, therefore the contents of CO2, SO2 and NO decrease and the content of O2 increases. So controlling the width of the high temperature zone in deep-bed sintering can efficiently reduce gaseous pollutants (CO2, SO2 and NO) in sintering tail gas.
Abstract: According to research on thermodynamic calculation and experiment of carbon dioxide and oxygen mixed injection (COMI) steelmaking process, material and energy equilibrium models of converter steelmaking with all hot metal by COMI process were established. The results show that COMI process is significant for converter steelmaking with all hot metal. It can not only overcome the problems of a large amount of slag and big splashing in a conventional converter, but also can improve the calorific value of converter gas, reduce the oxygen consumption per ton steel, lower the consumption of lime, and accommodate the amount of iron ore.
Abstract: A correlative formula which shows the relationship of temperature,nitride capacity and optical basicity was obtained by regression analysis.Two kinds of reaction mechanisms of nitrogen entering into slags were provided.The isograms of nitride capacity in CaO-SiO2-Al2O3-MgO (wMgO=10%) melts were depicted by regression equations.The results show that the nitride distribution ratio LN increases with decreasing[%Al]s in steel when the nitride capacity is a constant and LN increases remarkably with increasing nitride capacity when the[%Al]s is a constant.The interface between slags and molten steel with high nitride capacity has strong ability to reduce nitride in molten steel.Slags play an important part to remove nitride in molten steel and prevent from nitrogen pick-up during the production of ultra low-nitride steel whose solute nitrogen content is blow 3×10-5.
Abstract: Planar disregistries between various substrates and nucleated phases during liquid steel solidification were calculated. The relation between lattice disregistry and heterogeneous nucleation catalysis of liquid steel was analyzed. The results show that the smaller the disregistry is, the more effective the substrate is for promoting nucleation. The logarithm of undercooling is approximately linear with the disregistry between the substrate and the nucleated phase. A substrate is presumed as the highly effective nucleus for promoting nucleation if the disregistry between the substrate and the nucleated phase is lower than 8%.
Abstract: Based on production practice, the ABAQUS explicit dynamic simulation platform was used to investigate the metal deformation and flow rule during tube continuous rolling by the Baosteel Ф140 mm full float mandrel mill. The results show that the transverse metal flow is mainly from the groove top to sidewall, and the longitudinal metal extension occurs chiefly in the groove top area, while the outer wall metal of steel tubes slides forward relative to the inner wall metal. Transverse metal accumulation and longitudinal inadequate extension in the groove sidewall area are the main reasons to cause non-uniform wall thickness.
Abstract: The relationship between inclusions and the microstructure of the simulated weld-heat-affected zone (HAZ) in a microalloyed steel as well as low-temperature impact toughness was investigated. The results show that inclusions in the steel are mainly Ti2O3-Al2O3-MnS, these complex inclusions are well distributed and their size is less than 3 m. The microstrueture of HAZ consists of aeicalar ferrite, intergranular ferrite and small amount of lath bainite while the cooling time daring phase formation is short (T8/5=40 s), the prior austenite grain size is about 50 μm and the samples have good impact toughness under this welding thermal simulation condition. The size of prior austenite grains increases with the increase of transformation cooling time (T8/5=60 and 80 s), the increase of transformation temperature and the broadening of the transformation region make the promotion effect on polygonal ferrite induced by inclusions in the vicinity of the grain boundaries become more obviously, the intergranular ferrite grows up rapidly, the refinement effect of intragranular acicular ferrite is lowered to some extent, and the low-temperature impact toughness is decreased.
Abstract: A new type of high-strength and high-toughness low-alloy Mn steel was designed by multi-element alloying.The static CCT diagram,microstructure,fracture morphology of the steel,as well as the effect of heat treatment on its mechanical properties,were studied.The results show that the stability of under-cooled austenite in the steel is excellent,which makes the steel have high hardenability and tempering stability.After being quenched at 890 to 930℃ and tempered at 200 to 230℃,the steel obtains tempered lath martensite which makes the steel the optimum combination of tensile strength Rm and impact toughness Akv (Rm ≥ 1 500 MPa,Akv ≥ 85 J).A good performance-price ratio was determined by properly increasing the content of Mn which is abundant in China.
Abstract: The continuous annealing processing of transformation-induced plasticity (TRIP) steel was simulated in lab.The microstructure and mechanical properties were analyzed by optical microscopy (OM),scanning electron microscopy (SEM),transmission electron microscopy (TEM),electron-backscatter diffraction (EBSD),X-ray diffraction (XRD) techniques and tensile test.The factors influencing the stabilization of retained austenite and the strengthening mechanism of TRIP steel were analyzed.The experimental results showed that fine grains in the microstructure of Nb-bearing TRIP steel formed during continuous annealing processing because of the existence of Nb.The Nb-bearing TRIP steel has more retained austenite and more carbon in retained austenite than the TRIP steel without niobium.It is found that retained austenite in the Nb-bearing TRIP steel is bulky or thin filmy at ferrite and bainite grain boundaries and few fine globular ones exist in the ferrite matrix.Fe3C and (Nb,Ti)(C,N) are the main precipitates in the Nb-bearing TRIP steel after hot rolling.After continuous annealing,(Nb,Ti)(C,N) is the only main precipitates.Obviously the yield strength and tensile strength increase with increasing annealing temperature,which results from the precipitation strengthening of fine Nb-bearing precipitates.
Abstract: The corrosion behaviors of super 13Cr martensitic stainless steel were studied with high temperature and high pressure CO2 and H2S/CO2 test as well as electrochemical measurement at the simulated oilfield corrosion environment.The results show that with increasing temperature the uniform corrosion rate of super 13Cr martensitic stainless steel increases subsequently under CO2 corrosion environment,and the pitting is very slight.Under H2S/CO2 corrosion environment,the uniform corrosion rate of super 13Cr martensitic stainless steel changes little,but the pitting becomes severe.When the Cl- mass concentration is 160 g·L-1,the max pitting depth comes to 28 μm.The pitting potential of super 13Cr martensitic stainless steel is bigger than that of common 13Cr,and it decreases with increasing temperature and Cl- mass concentration as well as the presence of H2S,while it changes slightly in CO2 corrosion environment.The recovery potential of super 13Cr martensitic stainless steel is in the passivation zone under N2 and CO2 corrosion environment,and the higher recovery potential indicates that super 13Cr martensitic stainless steel possesses the superior re-passivation ability.At the same time,the presence of H2S makes the recovery potential and pitting potential decrease remarkably.
Abstract: Corrosion experiments of N80 steel were conducted under different CO2 pressures by a high temperature and high pressure autoclave. The corrosion rate of N80 steel was calculated by the mass-loss method, the micrograph, thickness and Ca content of the corrosion scales were observed by scanning electron microscopy, and the electrochemical properties were measured and analyzed by electrochemical impedance spectra and potentiodynamic polarization. The shear strengths between the corrosion scale and the N80 steel substrate were measured. The results show that with the increase of CO2 pressures the corrosion rate of N80 steel increases, the grain sizes of the corrosion scales show no obvious difference, and the amount of microcosmic flaws in the corrosion scales increases gradually. The resistance of the corrosion scale and the reaction resistance show the increase tendency. The shear strength between the corrosion scale and the N80 steel substrate decreases with the increase of CO2 pressure, leading to the increase in corrosion rate.
Abstract: Al-25Si-xFe-yMn alloys with the mass ratio of Mn to Fe between 0 and 1 were synthesized by spray deposition.The microstructure of the spray-deposited preforms was investigated by SEM,XRD and EDX.The results indicated that Mn addition could improve the morphology of Fe phases through forming particulate α-Al15 (Fe,Mn)3Si2 phase to replace acicular δ-Al4FeSi2 and β-Al5FeSi phases.When the mass ratio of Mn to Fe increased,the amount of particulate α-Al15 (Fe,Mn)3Si2 phase would increase,whereas the amount of acicular phases reduced.When the mass ratio of Mn to Fe increased to 0.83 or 1,only particulate α-Al15 (Fe,Mn)3Si2 phase could be observed in the deposited preform.
Abstract: The effect of sintering on the performance of two kinds of catalysts was analyzed under various conditions,and chemisorption characterization of catalysts was carried out to investigate the feasibility of substituting Cu-Zn catalyst for Fe-Cr catalyst in high temperature CO water-gas shift process (HTS).Results of activity evaluation experiments show that as a fresh catalyst,Cu-Zn catalyst has a higher activity than Fe-Cr catalyst,not only in the temperature range of low temperature shift (LTS),but also in the temperature range of HTS.On the other hand,sintering of Cu-Zn catalyst is obvious in the beginning stage at a relative high temperature of 450℃,but gets steady after 500 h,and in the steady stage the activity of Cu-Zn catalyst is still higher than that of Fe-Cr catalyst.The results of activity evaluation accord with those of CO chemical sorption.A CO water-gas shift process with substituting Cu-Zn catalyst for Fe-Cr catalyst was suggested in both HTS and LTS processes,in which the CO content could be removed to below 1% from the inlet content of 10%.
Abstract: Using water-atomized Cu-Al alloy powder as raw materials,Al2O3 dispersion-strengthened copper composite materials were fabricated by the internal oxidation method.The obtained composite materials were comprehensively characterized by field emission scanning electron microscopy (FE-SEM) and X-ray diffraction analysis.The results show that γ-Al2O3 nano-particles with a mean size of 6 nm are uniformly distributed in the matrix and the space distance between particles is about 30 to 50 nm.The conductivity of the hot extruded bars is 87% IACS and the softening point is 850℃.Without any intermediate heat treatment,copper wires of Ф1 mm in diameter were produced by direct cold drawing from the dispersion-strengthened copper bars of Ф25 mm in diameter.The tensile strength of these copper wires is 680 MPa.
Abstract: Sialon-bonded corundum castables were prepared by in-situ nitridation sintering with tabular alumina as the aggregate,fused white corundum fine,hydratable alumina,Si powder and ultra-fine alumina as the matrix.The effects of sialon content on their physical properties,high-temperature strength and thermal shock resistance were investigated.The phase composition and microstructure of the samples were characterized by XRD and SEM.The results show that with increasing sialon content the water demand of the castables increases,the cold modulus of rupture and bulk density decrease,the apparent porosity slightly increases,and the permanent linear change varies from little shrinkage to little expansion.The hot modulus of rupture and thermal shock resistance of the castables obviously improve with increasing sialon content,and the residual strength ratio increases from 16% without sialon to 50%.
Abstract: With the castable rheometer,L-box flowability test apparatus and self-flow test apparatus,the influence of water addition,dispersant content (FS10),aluminate cement content and α-Al2O3 content on the rheology and flowability of a corundum-based self-flow castable were researched,and the relationship between rheological properties and flowability of the castable were analyzed.The results show that with the increase of water addition (4.9% to 5.3%,mass fraction),the relative yield stress,relative plastic viscosity and relative average viscosity decrease,but the self-flow value and flow velocity increase.With the increase of dispersant FS10 (0.16% to 0.20%,mass fraction),the relative yield stress,relative plastic viscosity and relative average viscosity decrease,but the self-flow value and flow velocity increase.With more dispersant FS10 additions (0.20% to 0.22%),the relative yield stress,relative plastic viscosity and relative average viscosity increase markedly,but the self-flow value and self-flow velocity decrease remarkably.With the increase of aluminate cement (1% to 4%,mass fraction),the rheology and flowability parameters have some change,but not obvious.With the increase of α-Al2O3 addition (9% to 12%,mass fraction),the relative yield stress and relative average viscosity decrease,the relative plastic viscosity and self-flow value have little change,but the self-flow velocity increase.The relationship between rheology parameters and flowability parameters of the corundum-based self-flow castable is shown as the following:the self flow value and relative yield stress have good relevance;the flow velocity and relative average viscosity have good relevance.
Abstract: Using analytically pure Bi2O3 and Dy2O3 as raw materials,the Bi0.75Dy0.25O1.5 precursor was prepared by the reverse titration chemical coprecipitation method.By thermogravimetry-mass spectrum (TG-MS) analysis,the results show that the components of the precipitation are BiOOH and Dy(OH)3 with little BiONO3 and Bi2O2CO3.After calcining the precursor at 500℃ for 3 h,β-Bi0.75Dy0.25O1.5 could be obtained and its average grain size is 16.02 nm by the Scherrer formula from X-ray diffraction (XRD) analysis.X-ray fluorescence (XRF) analysis shows that the ratio of Bi/Dy extremely approaches to the theoretic stoichiometric ratio.Transmission electron microscope (TEM) analysis results show that the particles size is less than 20 nm in good dispersion.The mechanism of preparation reaction was studied by thermodynamic analysis.
Abstract: Due to the axial uneven wear of rolls and the problem of shape control brought by uneven wear, a three-dimensional elastoplastic dynamic finite element model of the roll system with a strip was built. The contact state between the roils and the strip was analyzed. The relation between the contact state and the distribution of wear along the axis of the rolls was theoretically analyzed, on the basis of which the rolling theory with transverse uneven lubrication was provided. Simulation results show that under the premise of guaranteeing strip quality, the distributions of rolling force and friction force between the rolls and the strip are homogenized obviously by changing the transverse friction coefficient between the rolls and the strip. It is proved that transverse uneven lubrication has positive effect on the contact state between the rolls and the strip. Finally, the feasibility of the rolling theory with transverse uneven lubrication was discussed.
Abstract: The Bayesian statistical theory was adopted to improve traditional neural network algorithms, and constraints representing network structural complexity were introduced to the network objective function in order to avoid over-fitting the networks and enhance the generalization ability. The improved networks were applied to strip thickness prediction in Jigang 1700 mm mill, and the prediction result is superior to that of traditional neural networks in forecasting accuracy, training time and network stability. Then, the Bayesian neural networks were used to predict the plasticity coefficient of strips. Finally, the real-time forecasts of exit thickness and plasticity coefficient of strips were synthetically utilized in the thickness control system of hot strip rolling to improve strip quality further.
Abstract: The features of word sense disambiguation (WSD) come from the context. Japanese has linguistic features of both Chinese and English at the same time, thus the feature extraction of Japanese is more complicated. Considering Japanese features, based on the proposed WSD logic model and applying the characteristics of information integration of the maximum entropy model, WSD was solved by the deep feature extraction method, introducing semantics and syntactics features. Meanwhile, for preventing the skewed assignment of lonely word sense, the word sense tagging of word sequences was completed with the BeamSearch algorithm. Experiment results show that compared with WSD methods which only focus on the surface lexical features, the disambiguation accuracy of the Japanese WSD system proposed in this paper increases 2% to 3%, and the WSD accuracy of verbs improves 5%.
Abstract: The failure modes, fracture distributions, load-deflection curves, strain curves of strands and ultimate bearing capacities of reinforced concrete (RC) beams before and after being fire-damaged were analyzed on the basis of experimental studies on the bending properties of the beams. It is shown that the flexural capacity and stiffness of the fire-damaged beam reduce in some degree. After strengthening with high-strength steel wire mesh and polymer mortar (SMPM) the bearing capacity of the fire-damaged beam increases significantly and can reach the level of the RC beam before burning.
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
