Abstract: Rational determination of production capacity is one of the technical problems during turning open pit into underground mining. With Shirengou Iron Mine as the object, seven projects feasible in technology were brought forward in combination with its specific situation. Considering the integral effect of technical, economical and social factors on the production capacity and according to mining codes, standards and regulations, it is obtained by fuzzy comprehensive evaluation and analytic hierarchy process that the best production capacity of Shirengou Iron Mine during turning open pit into underground mining is 2 150 000 t·a-1.
Abstract: 10 times remote sensed data(MSS/TM/ETM +/CBERS) from 1976 to 2006 in ATB Opencast Coal Mine were collected to set up classifications and identification of landuse based on remote sensing and interactively interpret the satellite images. The result indicates that the landuse type changed from simple to complicate during the 30 years, which is 4 types in 1976 to 12 types in 2006. A lot of land was destroyed and the total area is up to 2 730.7 hm2. Land reclamation began in 1993 and the reclamation area is 687.05 hm2 in 2006. Unfortunately, reclamation land degradation took place in several places because of coal waste rock self-burning, which is spreading. Efficient work has to do to deal with the problem.
Abstract: The effects of initial sulfuric acid concentration, stirring speed, and leaching temperature on leaching rate in the process of leaching vanadium with sulfuric acid from sodium roasting calcine of stone coal were investigated. The results show that initial sulfuric acid concentration and leaching temperature affect vanadium leaching rate apparently, and stirring speed nearly have rio effect on the leaching rate. The leaching process can be modeled with the shrinking core model, and the kinetics of the reaction is successfully described by the kinetics equation of chemical reaction control. The kinetic apparent activation energy E has been calculated as about 50.88 kJ·mol-1, which indicates that the leaching process is controlled by surface chemical reaction.
Abstract: The electrical resistivity of Dagang soil at different water content levels was measured by the means of DC four-electrode technology. The resistivity is lower at a higher water content level. During the measurement, the calculated value of resistivity is bigger at lower voltage grads; when the voltage grads increasing, it reduces and tends to a steady value, especially for low water content soil. A conductive model was presented, and soil conductivity was discussed by an equivalent circuit. At a lower water content level, the pathway of current flow is liquid phase pathway of pore water and solid-liquid phase pathway primarily via exchangeable ions. At higher water content the current passes mostly through pore water and the effect of exchangeable ions at the interface of solid-liquid phase can be ignored.
Abstract: The sulphide capacity of ultra low oxygen spring steel during manufacture process was calculated by KTH model, Young's optical basicity model and Tsao's empirical formula etc, and the sulphur distribution LS in production process was forecast by applying Turkdogan's and Hino's equations. The predicted values of sulphur distribution were contrasted with actual measured results and a comparatively accurate model for forecasting LS of ultra low oxygen spring steel was proposed.
Abstract: The microstructure consisting of dispersed cementite particles and ferrite grains was obtained by quenching and tempering in low carbon steel. The effect of cementite particles on the dynamic recrystallization of ferrite in this low carbon steel was investigated by hot compression tests at 700℃ and 0.01 s-1 on a Gleeble 1500 test machine. The results indicated that during hot deformation at 700℃ and 0.01 s-1, the dynamic recrystallization of ferrite takes place mainly by particle stimulated nucleation. At the beginning stage, particle stimulated nucleation occurs firstly near coarser particles (larger than 1 μm). At larger strain, particle stimulated nucleation also occurs near relatively small particles (between 0.5 and 1μm) due to accumulative strain.
Abstract: Three medium-carbon vanadium-microalloyed steels were designed and experimentally prepared, with carbon contents of 0.26%, 0.34% and 0.42%. The effect of carbon content on the formation of intragranular ferrite (IGF) in the steels isothermally treated at 600, 550, 500 and 450℃ were studied. Vickers hardness test was carried out for the steels isothermally treated at different temperatures. The nano-hardness of grain boundary ferrite (GBF) and IGF was also measured. Nucleation sites of IGF were then discussed. The results showed that the amount of non-eutectoid ferrite increased, the grain size of ferrite decreased, and the hardness was enhanced with increasing carbon content, if isothermally treated at the same temperature. In samples isothermally treated at 500℃, the nano-hardness of GBF was found higher than that of IGF. The nano-hardness of both GBF and IGF increased with the increase of carbon content, but IGF's varied little. It was also found that appropriate inclusions and pre-nucleated IGF could be nucleation sites of IGF.
Abstract: Welding thermal simulation, metallographic analysis and transmission electron microscope (TEM) were used to study the metallurgical microstructure and fine structure of the coarse grain heat-affected zone (CGHAZ) of in-service welding and the zones that subject to second thermal cycle at different peak temperatures. The results show that the main metallurgical microstructures of the CGHAZ of in-service welding are granular bainite and lath bainite. After second thermal cycle, the types of mierostructure have no change, but the shape and amount of each kind of microstructure and the grain size of original austenite are different when the peak temperature of second thermal cycle is different. Observing by TEM, the fine structures of each HAZ are ferrite laths and M-A constituents that distribute on or between ferrite laths. The M-A constituents in the CGHAZ of in-service welding are main strip-shaped. After second thermal cycle, the M-A constituents in the intercritically reheated CGHAZ are refined and lower bainite that has typical midrib morphology produces in the zone.
Abstract: The influences of B content and Nb, V micro-alloying on the impact toughness of low carbon boron steel were investigated by impact tests of low carbon boron steels with different boron contents and of Nb, V micro-alloyed low carbon boron steel. The results show that the B content of 0. 000 6% to 0. 0015% can improve the impact toughness of the steel, but the B content more than 0. 003 96 decreases the impact toughness. Nb, V micro-alloying with appropriate Al can increase the impact toughness of the steel, especially after heat treatment. It is disadvantageous that the Ti content is higher than 0.03% to the impact toughness of low carbon boron steel and micro-alloyed low carbon boron steel.
Abstract: 6061-T6 aluminum alloy thin sheets of 1 mm in thickness were welded by friction stir welding. Process parameters for the welding were investigated, and the mechanical properties of the welded joint such as Vickers hardness, tensile strength and elongation were tested. Metallographic microscope, SEM and TEM were used to analyze the microstructure of the welded joint. The result shows that for 6061-T6 aluminum alloy thin sheets of 1 mm in thickness, the best welding condition is the rotating speed of 1800 r·min-1 and the welding speed of 1000 mm·min-1. Under this condition, the Vickers hardness, tensile strength, and elongation of the joint are about 80%, 103%, and 54% as large as those of parent material, respectively. These mechanical properties are in agreement with the microstructure.
Abstract: Equilibrium phases in Waspaloy superalloy and the effects of element content on them were studied by Thermo-Calc software. The results show that a higher C content leads to a higher content of carbides, but no obvious effects on their precipitation temperature. With the increase of Al and Ti, the precipitation content and precipitation temperature of γ' are raised respectively; especially Al has a more important effect. With increasing the content of Ti, the main forming element of MC, more MC can be achieved, but there is no obvious change in precipitation temperature. Cr can not change the precipitation content of M23C6, but increasing the Cr content can enhance the precipitation temperature.
Abstract: The paper investigated the effects of different powders on the properties of heat-resistant alloys prepared by metal injection molding (MIM), which include sintered density, microstructure, mechanical properties and corrosion resistance. The properties of heat-resistant alloys made of element mixed powders with iron carbonyl powder and gas-atomized powders were tested. The results show that both the mechanical properties and corrosion resistance of the former are superior to those of the latter. For the best sintered samples made of element mixed powders, the relative density, tensile strength and corrosion loss weight rate are 98.1%, 510 MPa and 1.3 mg·cm-2, respectively. There are no obvious differences in their microstructures, which are composed of Fe-Cr ferrite a phase.
Abstract: Magnesium ferrite is a kind of main bonding phase in magnesia refractory materials. Using the powder mixture of active magnesia and chemical reagent Fe2O3 as starting raw materials, DSC experiments of the synthesis reaction of magnesium ferrite were conducted respectively at scanning rates of 10, 15, 20 K·min-1 in static air. The kinetic parameters of the synthesis reaction of magnesium ferrite were calculated by the Kissinger equation, the Flynn-Wall-Ozawa equation and the Achar-Brindley-Sharp-Wend-worth equation. The results show that the formation mechanism of magnesium ferrite obeys the random nucleation and rapid growth model, and the activation energy of the reaction is between 626.83 and 652.60 kJ·mol-1.
Abstract: The feasibility of iron-smelting and making glass-ceramics from unwieldy hematite of Xuanhua Iron Mine in Hebei Province, China by melt-reduction method and casting technology was analyzed to prepare pig iron used in steel-making and glass-ceramics for building decoration. By using orthogonal design method, slag-iron separation and slag crystallization were investigated at different ratios of raw materials, and the optimum proportioning by weight of raw materials which could be used in industrial test was determined as the following:hematite 77.3%, alumina 2.2%, quicklime 13.7%, fluor 5%, sodium oxide 1.8%, and coke 5.5%. The phase composition and characteristics of glass-ceramics products were determined by comprehensive methods such as optical microscopy, X-ray diffraction, and physical and chemical properties test.
Abstract: The total electric conductivity of Na3AlF6-Al2O3 slag and the effect of added CaO on the electric conductivity of the slag were investigated by the Ac impedance method of electrochemistry. Equivalent circuits were proposed according to the measured impedance spectra. EvolCRT electrochemical software was used to simulate the impedance data. The correlations of conductivity to slag composition and temperature were studied. The addition of CaO increases the electric conductivity of the system.
Abstract: A mechanical model was established for the forging drawing process of rectangular block with a horizontal V-shaped anvil, and the quantitative physical simulation and productive experiment of the process were carried out. It is showed that the forging method with a horizontal V-shape anvil can realize no transverse tensile stress forging, improve transverse mechanical properties and achieve uniform forging for heavy axial forgings. The ratio of transverse mechanical properties to longitudinal mechanical properties is about 1.00 at the same position of heavy axial forgings.
Abstract: In the rolling procedure of eccentric shafts by cross wedge rolling, the non-symmetry of rolling force in rolling zone is a significant characteristic. The force difference in rolling zone of eccentric shafts during cross wedge rolling was calculated by finite element method and its influencing factors were systematically analyzed. The mechanism of influencing factors on the force difference was clarified. Finally the influence degree of each influencing factor was evaluated.
Abstract: Aimed to the time variations of machine parts' stress and strength, a time-dependent mechanical design method, in which time-variable and random factors were taken into account, was proposed on the base of the calculation method of reliability incorporating time varying and uncertainty. The proposed method was analyzed using present time as the starting point. Stress and strength were considered to be affected bY random factors. Also, the distributions of stress and strength at any time t were modeled. A solution to the calculation method was given. Although the method is based on the time-dependent reliability model, it can be applied to other fields such as structural engineering.
Abstract: Aimed at a composite fault of rotor failure and weak roller bearing fault, a fault diagnosis method based on empirical mode decomposition (EMD) was proposed to separate the coupling features of the composite fault and to extract the fault feature of the roller bearing. Signals were decomposed to obtain several intrinsic mode functions (IMF) by EMD. Main components are confirmed by calculating the correlation coefficient of every IMF and original composite signal, and false components were removed at the same time. Finally low-frequency rotor fault feature was extracted by FFT from the low-frequency component of main components, and high-frequency modulate feature of the roller bearing was extracted by Hilbert envelope demodulation from the high-frequency component of main components. Simulation and experiment analysis results indicate the validity and the practicability of the method proposed.
Abstract: A novel method for global optimization, multi-sense swarm intelligence algorithm (MSA), was presented to solve continuous function optimization problems. Inspired by the artificial fish-swarm algorithm (AFA) and the FS algorithm (free search algorithm, FSA), the search mechanism of MSA combined large scale exploration and local precise search; even more, in this algorithm, the unit employed both visual information for quick approaching to local optimization solution and pheromone information to avoid overcrowding and to guide itself to global solution. Simulation shows that MSA has strong robustness, good global convergence, quick convergence speed and high convergence accuracy. At last, MSA was applied to feed-forward neural network training. The result shows that this algorithm is fit for the application.
Abstract: A QoS solution for CM which is a kind of network-access equipment in HFC network was proposed by analyzing different network QoS mechanisms and studying the DOCSIS1.1 QoS standards in-depth. A model for CM QoS mechanism was designed to ensure providing different QoS for different kinds of IP data, and the function of each module was described in detail. The dynamic service initiation technology was introduced lately, and finally the development of HFC network QoS mechanism was reviewed.
Abstract: The standard FCM algorithm is noise sensitive because of not taking spatial information into account, and it considers that each feature datum has the same contribution to classifying results. To overcome the above problems, this paper presented a modified FCM algorithm accounting for pixel spatial information based on gray histogram weight. The proposed algorithm was realized via introducing a gray histogram weight in the objective function given in Szilagyi's algorithm. Experimental results on both artificial synthesized images and realistic images demostrated the sound performances of the proposed algorithm.
Abstract: Atom propositions are the basic unit of symbolic logic. The relationship between atom propositions' relativity and logic calculation was analyzed. In classical two-valued logic, the truth value of the proposition logic calculation result only bears on the truth value of the proposition which participates in the logic calculation, but is independent of the idiographic content in the proposition. In probabilistic logic, proposition logic calculation is decided by the relationship of propositions. The different propositions with the same truth value can not have the same logic calculation result. Implication connectives which are compatible with classical two-valued logic were defined, and they overcome the shortcoming that conditional probability can not be used to inference.
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
