Abstract: According to the structure characteristics of joint rock mass in the south slope of Yanqianshan Open Iron Mine in China, a 3-D joint network was simulated and shown by Monte-Carlo random simulation technique. The spatial information of rock mass was visually displayed. Based on the fundamental theory of damage mechanics of rock mass and the 3-D network simulation technique, the probability distributions of random matrix of the damage tensor on joint rock mass were studied. It is shown that the elements of the probability damage tensor matrix obey the normal distribution.
Abstract: By using UDEC2D technique, this paper analyzed coal and rock movement laws, the deformation and failure characteristics of coal and the major principal stress in the process of top-coal caving in steep thick seam. The failure mechanism of coal and the movement trend of rock on the top-coal caving working face were discussed. The results showed agreement with the field conditions, which is of important theoretical meaning to direct the practice in the similar engineering.
Abstract: The design proposal and correlation technique for developing the Deposit Database Management System (DDMS) based on volume visualization technique were discussed. The system can accomplish figure data management, attribute data management and spatial data analysis. It realized data compress storage by octree data structure and reached the perfect integrating of map and data by uniting MIS and GIS.
Abstract: An experimental model with two cavities was made of concrete, ore fines and tails in the laboratory. Simulation experiments were conducted to study the characters in Ground Penetrating Radar (GPR) images of every filling body by filling water, sand, mud and air in turn. Experimental results indicate the radar image changes with gob filling. Field investigations were carried out at Changba Lead-zinc Mine in China. The main detecting method for gob and its filling by GPR was expounded. The space distribution of gob was obtained. The filling can be well identified by analyzing the radar images. The results of field experiments show GPR technique is useful, high-efficiency and nondestructive for detecting gob and its filling.
Abstract: The treatment of power plant sewage based on the Suspended Biofilm Bed Reactor (SBBR)-filtra tion-ozone mixed process was studied. The system can endure various organic load impact and hydraulic load impact. The best removal rate of CODcr reached 95% and the mass concentration ranged in 10-30 mg/L. The removal rate of phosphorus was over 50% and the mass concentration lower than 0.5 mg/L. The removal rate of NH3-N was over 80%. The removal rate of turbidity reached 84%, more than 99.9% of bacteria had been killed and the bacteria concentration was 1/L.
Abstract: Landfill leachate, whose main pollutants are organic matter, heavy metals and ammoniacal nitrogen, is a kind of poisonous, harmful and organic wastewater. The pretreatment of landfill leachate by flocculation-adsorption was investigated. Polyaluminium chloride (PAC) was used as the flocculant and its optimum dosage was 500 mg/L. The adsorbent was self-made modified bentonite. Experimental results showed that approximately 79% of CODcr and 46% of ammoniacal nitrogen were removed. As to heavy metals, the removal ratios were from 53% to 98% according to different kinds of landfill leachate.
Abstract: The ore phase structure, mineral composition and metallurgical property of Brazilian MBR lump ore were introduced. Brazilian MBR lump ore has excellent metallurgical property, and both its beginning and ending temperatures of assimilation during melting are higher, however the assimilation velocity becomes a little slower. The application of MBR lump ore shows that the charge grade of BF increases, the iron ore consumption reduces, the equivalent coke ratio declines, and the cost of iron decreases with a proper mixture of Brazilian MBR lump ore. It is shown that Brazilian MBR lump ore plays an important role in improvement of BF technical and economic production indexes.
Abstract: The activity coefficient of Al in molten Cu decreases with the increasing of electric current which is applied to the liquid alloy of Cu-0.2%Al. To further investigate the mechanism, the quenching experiment of the liquid Al-Cu alloy was conducted. The results show that there is a remarkable change in structure, in which the solute congregates along the direction of the current especially for DC current. The activity coefficient change mechanism of Al in molten Cu-0.2%Al alloy treated by electrical field was discussed. On the basis of this result, a model of the change in solute activity in the liquid alloy treated by electrical field was proposed.
Abstract: The site preference of alloy elements Fe and Ti in YCo5-based compounds with CaCu5 structure was studied by employing interatomic potentials and Modified-Bragg-Williams model. The result suggested that the elements Fe and Ti prefer to occupy the 3g sites, which matched with experimental results.
Abstract: The effect of C and Mn contents on ferrite nucleation rate during Deformation-Enhanced Ferrite Transformation (DEFT) in low carbon (Mn) steels was investigated. The results show that the deformation causes such a higher defect density in austenite grains, which leads to extra sites for nucleation both at the austenite boundaries and intragranular, that ferrite grains are refined dramatically. The addition of C or Mn is favored to strain cumulated in the austenite, which also increases the nucleation sites, resulting in more pronounced ferrite grains refined. The promotive ability of C to refine ferrite grains is, however, much greater than that of Mn.
Abstract: Superficial banded structure was observed on hot strips of low carbon steel. The formation mechanism of the banded structure was discussed and some measures were proposed to minimize the superficial flows. Experiments were carried out on the surface local elongation of cold bending specimens with 8 mm and 5 mm in thickness respectively. The results indicated that the bending flaws of thick strips arise mainly from the existing of the superficial banded structure.
Abstract: Infrared spectrum, X-ray diffraction, transmission electron microscopy and conductivity measurement were employed to investigate the properties and structure of polyaniline samples, which were synthesized by emulsion polymerization with different concentrations of ammonium peroxydisulfate and dodecyl-benzene sulphonic acid. The electrical conductivity of polyaniline varied with the molar ratio of oxidant and doping agent to aniline and reached peak at some value, while some characteristic peak values at their infrared spectrum changed their location and intensity relatively. The crystallization degree of different samples exhibited distinction due to different synthesis conditions. Under the optimum synthesis condition, a fibril morphology and higher crystallinity were observed. The results indicate that the change of oxidation and doping condition affects the ratio of benzenoid to quinoid ring and the orientation order of the polyaniline chain, which are important factors to decide the conductivity of polyaniline.
Abstract: An Al-1%Si bar with 8 mm in diameter and single crystal was made with self-made vacuum vertical continuous unidirectional casting equipment. The microstructure evolution and stability during continuous unidirectional solidification were studied. The Si distribution of particles in Al matrix was analyzed and a method was proposed that can make Si diffuse in Al homogeneously.
Abstract: WC-12Co and FeAl powders were sprayed on SUS316L stainless steel matrix by HVOF or DGS process respectively. The particle morphology, the grain size distribution and the DTA curve were investigated and the corresponding effects on the quality of spraying coatings were discussed. The results from the measurements of surface roughness and microhardness and the observations of coating morphology and X-ray diffractometry indicated that highly spheroidised and homogeneous powders lead to homogeneous microstructure, good compactness and strong bonding between the coating and the matrix. From the present experiment it can be concluded that quality of WC-12Co coating deposited by HVOF is the best, but the processing parameters of FeAl coating deposited by DGS need to be optimized further.
Abstract: Electrical back scatter pattern (EBSP) was used to investigate the texture evolution rule of deep-drawing sheet St15 during recrystallization annealing. When the heating rate is 30℃/h, the recrystallization temperature of deep-drawing sheet St15 is about 560℃, the recrystallization finishing time is nearly 2 h, and the strongest component of the recrystallization texture is {100}<110>. γ fibre texture in St15, especially {111}<112>, strengthens with incresing the annealing temperature. When the holding temperature is 700℃, {111}<110> texture in St15 strengthens with increasing the annealing time, and after holding for 4h{111}<112> texture gradually. When the holding time reaches 13 h, a satisfied annealing texture is achieved.
Abstract: In order to produce diffusion-rolling sandwich panels under small reduction, a bonding assistant coat which mainly contains Cu, Zn, Mn and small amount of Si, Sn, Ni, B and rare earth elements was designed for carbon steel plates at 850℃. The results of SEM and rolling showed that atom diffusion between the carbon steel plate and the bonding assistant coat took place, the interface combination was satisfied and the thickness of bonding assistant coat accorded with small reduction later.
Abstract: The superplasticity mechanism of duplex stainless steels was studied mainly by means of crystallography. On this basis, the Electron Back Scatter Diffraction (EBSD) system was used to obtain the orientation distribution, Tango-mapping and Mambo-pole figures. Microstructural studies associated with transmission electron micrographs observed in the specimens during superplastic deformation suggest that superplastic process occurs mainly by strain-induced phase transformation and dynamic recrystallization, grain boundary sliding and grain re-orientation mechanism.
Abstract: By using a Gleeble-1500 thermomechanical simulator, the laws of dynamic continuous cooling transformation and microstructure evolution of interstitial free steel (IF steel) produced by TSCR were investigated. It was found that the transformation temperature Ar3 decreases with the cooling rate increasing, which is beneficial to the low-temperature finish rolling and more excellent property of IF steel. The hardness increases with increasing the cooling rate. When the cooling rate rises from 1℃/s to 30℃/s, the HRB value correspondingly increases from 53.43 to 68.3. As a result, the strength improves with increasing the cooling rate.
Abstract: The low-cycle fatigue test of 800 MPa-grade ultrafine-grained HSLA was done. The result showed that the low-cycle fatigue cycle characteristic of the material is cyclic softening under the experimental condition and the softening velocity increases with the increasing of strain amplitude. Observations of the fatigue fractography revealed that fatigue cracks start from the material surface and distribute along the fracture border, which have multi-fatigue origins.
Abstract: The feasibility of several perovskite-type oxide materials used as the cathode for Molten Carbonate Fuel Cells (MCFC) was discussed by studying the stability of the materials in MCFC molten carbonate. Experimental results showed that SrFe0.5Co0.5O3 has conspicuous mixed electric characteristic but the major limit is dissolution in the electrolyte of molten carbonate. La0.8Sr0.2MnO3, La0.8Sr0.2Ce0.1Mn0.9O3 and La0.8Sr0.2Ni0.1 Mn0.9O3 were filtered by a lot of Li+ and dissolved a large amount of Sr2+ in molten carbonate, and thus these several materials could not be used as the cathode for MCFC. It was proved by experiment that the stability behavior of LaMnO3 which had been lithium-loaded beforehand was outstanding in MCFC molten carbonate.
Abstract: Lithiated titanium complex oxide Li4Ti5O12 was prepared by solid-state method. The influence of reaction time on the structure and electrochemical performance of Li4Ti5O12 was investigated. The samples with the reaction time of 2 h and 4 h show a good reversibility, and their specific capacity after 30 cycles is as high as 159 mAh/g when charged and discharged at 80 mA/g.
Abstract: LiFePO4 cathode materials were prepared by microwave processing with a domestic microwave oven. LiFePO4/C composites were synthesized by carbon-coated to improve the capacity and rate capability. The microstructure and electrochemical performance of the composite were studied by X-ray diffraction, scanning electron microscopy and constant current charge-discharge experiment. The results indicated that the LiFePO4/C composite with 4% carbon exhibited a higher reversible specific capacity of 109 mAh/g at 40 mA/g and an excellent rate capability.
Abstract: A finite element analysis model for calculation of the gap and the rolling pressure axial distribution of different work roll contours under the condition of cool roll (initial rolling) and hot roll (stable rolling) respectively is established by treating aluminum foil rolls and aluminum foil integrally. The influence of work roll contour on aluminum foil profile was analyzed. It is suggested that the top work roll take AFW (Aluminum Foil Work Roll) contour and the bottom work roll take flat contour in aluminum foil rolling.
Abstract: The integrated control of gauge and shape in hot strip mills is important and difficult. Rolling force is the key factor of gauge control, also is one of the major factors of shape control. A strategy was introduced to optimize the load distribution helpful to shape control and the relative parameters were obtained by means of immune genetic algorithm. Experimental results show that the strategy is valid, which provides another way for the integrated control of gauge and shape and can be used to guide production in practice.
Abstract: In order to develop an adaptive model for automatically generating rolling schedules that comply with practical operations in heavy plate rolling, the techniques of Case-Based Reasoning (CBR) and Knowledge Discovery in Database (KDD) are introduced in the modeling process. In the model CBR not only is used for storing and retrieving the cases, i.e. schedules by which high-quality products have been rolled, but also generates an initial schedule for the material to be rolled according to the similarity in attributes between the material and the stored cases. KDD is introduced to find the rules from the operational data records to modify the initial schedule if there is difference between the ongoing rolling practice and the case applied. The experimental results of comparing the schedules against the practical rolling data show that the schedule generated by the new model is more reasonable and conformable to the actual rolling practice than that generated by traditional methods, which indicates that the method proposed in this paper is a promising method for rolling schedule generation modeling.
Abstract: Computer-aided design and Web technology are applied to mechanism design, and the software system for the design of cam-linkage combined mechanism based on Web is developed. The system is established on the base of the dimensional synthesis theory of combined mechanism and the optimization theory of considering the minimum horizontal dimension as the optimizing aim. The program language in this system is Java, and the modularized design and Object-Oriented Programming (OOP) techniques are also utilized.
Abstract: An axial symmetric FEM model is established for API 8 tooth round thread casing connection. The contact behavior and stress-strain distribution in the connection area are analyzed when the connection is screwed down by machine, especially under different end pitch values. Through investigating the effect of end pitch, it is proposed that the best pitch of the hoop should be 50-55°. This result has been successfully used in practice.
Abstract: Based on the fluidized bed theory, a series of thin layer wheat drying experiments were carried out in an electric drying oven with gentle breeze in it to simulate the wheat drying process in fluidized bed. As a result, the wheat drying correlation was developed from those experiment data for predicting the wheat drying time in fluidized bed. An experiment system combining fluidized bed with heat pump was designed and experiments on which indicated that the correlation could predict the drying time reasonably. Further economical analysis proved the efficiency and a promising future of the fluidized bed drying with heat pump.
Abstract: On the basis of the comprehensive analysis of major technical factors affecting iron concentrate grade index, the basic thought and method to optimize iron concentrate grade index are proposed by taking technical and economic factors into account, establishing a dynamic mathematic model and adopting multi-objective optimization decision-making techniques. The basic design method and main functions of the iron concentrate grade optimization system built according to the thought are introduced and the main operating steps are exemplified.
Abstract: A PID control strategy based on RBF network and combining with Smith estimator was proposed for dead-time monitor AGC system. Simulations on classical monitor AGC, Smith estimator-based AGC and intelligent PID-based AGC were done. The simulation results indicate that the convergent speed of the intelligent PID-based AGC is faster than the others, and it has satisfied adaptability and robustness.
Abstract: A Radial Basis Function (RBF) neural network learning algorithm based on immune recognition principle is proposed. In the algorithm, the input data are regarded as antigens and the compression mappings of antigens as antibodies, i.e., the hidden layer centers. This algorithm can choose the number and location of the hidden layer centers by applying the principles of recognition, memory and learning, and can determine the weights of the output layer by adopting the least square algorithm. The predicted results of the mechanical property of hot-rolled steel bars show that this algorithm has the advantages of less computation and high precision compared to the K-means algorithm.
Abstract: The idea of primary component analysis was applied to eliminating the singular point and selecting the intersection of raw log data sets according to the characteristics of raw log data. Then kernel Fisher method was used in the intersection, which remedy the shortcoming of linear differentiate methods. By combining the two method, primary component analysis and kernel Fisher, the differentiate capability was improved and the practicability is testified in application.
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
