Abstract: Through coal spontaneous combustion experiment and relation experiment between the particle size and the oxidation character of loose coal, some calculation formulae of characteristic parameters were obtained in the process of coal spontaneous combustion. According to these theories of porous medium hydrodynamics, mass transfer and heat transfer, the mathematical models of the air leak field, the oxygen concentration field and the temperature field were set up. By experimental and theoretical analysis a 3-D dynamic mathematical model of coal spontaneous combustion was proposed, the method of ascertaining the boundary condition of the model was analyzed, and the finite difference method was adopted to solve the 2-D mathematical model.
Abstract: The general status of Huogeqi Copper Mine in Inner Mongolia was introduced in detail including the environment, geographical condition, and character and stability of the gob area. The stability of the gob area was analyzed and calculated based on Coulomb Law and the boundary element numerical simulation method. By comparison, the safety coefficient calculated by theoretical analysis is agreeable with that by numerical simulation. According to the result, combined with engineering practice, the stability of the gob area was analyzed and the corresponding disposal method was proposed. The successful application to the gob area at Huogeqi Copper Mine shows that this method is both convenient and economic.
Abstract: With increasing development of digital and communication monitoring techniques, the quantity of obtained information about the damage process of rock mass around large scale mined-out areas is significantly increased. The information includes various figures and vectorgrams in digital form. Data mining and analysis for monitored breakage information from rock mass around mined-out areas using wavelet analysis, non-equilibrium statistics and neural network techniques will be beneficial to correct the understanding of the whole damage process of rock mass around min-out areas.
Abstract: According to the in-situ information about the load-carrying capacity descent of pier rock mass foundation, the multiply anchor-pile technique in a single bore was adopted in the reinforcement. The mechanism of the technique was analyzed in the rudimental stage. By using of numerical simulation, the load-carrying capacity of pier foundation and anchor-piles were also calculated after reinforcement. The result shows that, after reinforcement the load-carrying capacity of pier rock mass foundation was increased largely. Under the loading of 600 kN/m from the pier, the maximum value of vertical displacement of anchor-piles and rock mass was less than 2 mm, and that it is keeping synchronous in the displacing process.
Abstract: Based on the heat-transfer mechanism of a sealed-in air heat insulation layer, an optimal thickness formula of the air layer is derived by the extremum analysis method. Calculating results show that this is an economic and effective method to reduce the temperature difference of the tank wall, and prevent and control cracks in the wall of a concrete oil tank.
Abstract: The electrolysis of the wastewater in the dyestuff factory and the simulated organic wastewater was investigated with a Ti-based IrO2-Ta2O5 coating electrode produced by a pyrolytic process and a ternary oxide electrode with addition of Sn and Pb, respectively. COD experimental results showed that organic components in the wastewater could be decomposed electrolytically by using the IrO2-Ta2O5/Ti electrode. With the electrolysis time increasing, the COD value dropped. The electrolytic efficiency was high at high COD values. At low COD values, adding NaCl into the organic wastewater had a good promotive effect on the electrolytic decomposition of organic components. Adding the third elements, Sn and Pb, into the electrodes could promote the electrolytic decomposition of organic components in the wastewater. The COD decomposition rate of electrolyzing the wastewater increased by 11.2% by using the PbO2/IrO2-Ta2O5/Ti electrode compared with that by using the IrO2-Ta2O5/Ti electrode.
Abstract: The biodegradation efficiency of two petroleum-degrading strains SY1 and SY2 was investigated with synthetic seawater. Experimental results indicated that their biodegradation rates were 41.3% and 42.6% respectively without addition of minor nutrients. Both the strains can adapt to typical ocean conditions including temperature, pH and dissolved oxygen, and also degrade a broad spectrum of hydrocarbon substrates. The kinetic model of biodegradation of crude oil by these two strains were also established, which abides by Michealis-Menten equation.
Abstract: Transmission electron microscopy (TEM) and nanobeam EDS technique were used to investigate the strain induced precipitation behavior during relaxation process after deformation in the non-recrystallization temperature range of a ultra-low carbon steel containing Nb, Ti and Mo. The experiment results indicate that after 30% predeformation at 850℃ and 900℃, two kinds of precipitates, combination of Nb and Ti and a few pure Nb, occur in the steel during isothermal holding. The atomic ratio of Nb to Ti in particles increased and pure Nb particles disappeared with the relaxation extended. After longer holding, some Nb and Ti atoms in the lattice sites of the precipitates were replaced by Mo atoms. The content of Mo in the precipitates rose with the relaxation time increased. The shape of the precipitates is mainly irregular and the density and average size of precipitates are related to deformation temperature and relaxation time.
Abstract: The evolution of microstructure and hardness of low carbon plate steel during tempering at 500-700℃ was investigated. The steel was manufactured by RFC (Relaxation-Precipitation Controlling phase transformation) technique. A part of the plate was reheated to 930℃ and held for 1 h before quenched into water (RQ) as a comparison. RFC plate softened slowly with the increase of tempering temperature and even became harder between 600 and 650℃. Despite of a lower original hardness of RQ plate it softened faster during tempering. RPC steel and RQ steel are constituted by bainite and martensite microstructures before tempering. The microstructure of RFC steel did not change obviously except some bainitic laths coalescing were detected by means of SEM during tempering, while the boundary of bainitic laths of RQ steel disappeared quickly and finally formed polygonal ferrite forms accompanied a dramatic decrease in hardness. These results indicate that the thermo-stability of fine non-equilibrium microstructure is tightly related to their history.
Abstract: The growth behavior of ferrite grains under three different thermal mechanical processing schedules was investigated by SEM, EBSD (electron back scattering diffraction) and X-ray diffraction techniques. Results show that the relative contribution of recovery, recrystallization and grain growth was related with the status of second-phase particles and the orientations of ferrite grains. The ultra-fine ferrite grains produced by deformation-enhanced transformation had less driving force to recrystallize since less stored energy was left after deformation. They grow apparently because of the late precipitation of second-phase particles. Although ferrite deformed below A1 temperature gained the highest stored energy and strongest texture, only partial recrystallization occurred in such grains because of the effective pinning of second-phase particles. The intensity of <111> fiber texture decreases more apparently than that of <100> fiber texture. When deformed at α+γ dual-phase region, the ferrite grains grew in the way of recovery. The recrystallization tendencies of grains with <111> and <100> orientations are different.
Abstract: The numerical simulation of solidification processing for Si-Al alloys prepared by spray forming was adopted by considering heat radiation in the cooling process of droplets. A relationship among droplet velocity, heat transfer coefficient, droplet temperature, cooling velocity of droplets, solid fraction and axial distance was acquired. The variations of droplet temperature and solid fraction before and after heat radiation is considered. The influence of atomization pressure and axial distance on solid fraction was also discussed.
Abstract: The two completely immiscible metals beryllium and aluminum were welded by controlling the laser beam energy and the welding speed. A satisfactory welding joint microstructure were obtained. The micro-structure of the joint and heated effected zone is typical eutectoid structure.
Abstract: The microstructures of as-deposited and extruded ultrahigh strength aluminum alloys by spray-forming were investigated. The aging-curves and tensile properties were tested after solid-solution treatment and aging treatment. The result shows that in as-deposited alloys, many porosities are obvious. In extruded alloys, however, there are large amount of Cu-rich particles. The solid-solution treatment temperature should not be higher than 490℃ because much of grain-boundaries melt in this temperature. At 120℃, the time to obtain hardness peaks ranges from 15 to 25 h. At 135℃, the relationship is obvious between the time and the composition of the alloys:The more Zn contented, the less the time; the tensile strength of the alloys keeps on about 700 MPa.
Abstract: A method of two-step surface pretreatment utilizing two kinds of solutions to etch respectively the surface WC and Co in cemented carbide substrates was investigated. Diamond films were deposited by means of the High Current Extended DC Arc Plasma CVD Equipment. The results showed that the two-step method can effectively remove the Co in cemented carbide substrates and obviously roughened the surface of the cemented carbide. Enhancements both on the quality and adhesion of the diamond coatings were observed.
Abstract: Waveguide membrane on Si basement was fabricated by So-Gel method with a special kind of organic Si as raw material. After a serial of tests including thickness test, optical test and XPS test, it was concluded that this membrane was thick enough and has good quality. Since Sol-Gel method always causes chap and split, a method how to deal with it was discussed. Finally, how to fabricate an arrayed waveguide grating with the membrane was also introduced.
Abstract: The mechanical properties, chemical composition control and cleanness control of HSLC steel were introduced and the strengthening mechanism was discussed. It is pointed out that the mechanical properties level of HSLC steel produced by EAF-CSP technology in Zhujiang Iron Steel Co, Ltd is located at the same position with that of microalloyed HSLA steel produced in foreign CSP plants. The main points of chemical composition and cleanness control were listed and the terminal point control as well as low nitrogen control technology of EAF was developed. It was found that there existed nano-scale sulfides, oxides, nitrides and carbides in HSLC steel. Similar to HSLA steel, the precipitation strengthening mechanism is available to HSLC steel. The nano-scale iron carbide would be the main strengthening phase.
Abstract: The weakness of traditional methods for flatness defect pattern decomposition was analyzed and a gaussion decomposition method for strip flatness defect patterns was presented. This method not only improves the regression accuracy of strip flatness curves, but also facilitates flatness control, especially in the control system of subsection cooling and altering convexity of a roller by local pressure.
Abstract: Load sensors were installed at the adjusting device in the sector segment of a slab continuous casting machine. The force between the cast slab and the supporting roller due to the static pressure of molten steel was tested. By the sensors, on-line detecting the end of a liquid core was realized. The result of field testing in PanSteel shows that the detecting method is very available.
Abstract: An automatic control system and its corresponding simulation system developed for steel wire heat treatment were presented. The control system consists of an industry control system and a Programmable Logic Controller (PLC) system. The software, including configuration program, heating model program, PLC logical control program and a database, could control the temperature of a muffle furnace and a lead bath furnace based on production plan, product specification and technique or adapt the speed of steel wires to match the temperature of the current muffle furnace so as to obtain the optimum effect of heat treatment. The simulation system contained a simulation software, a combustion mathematical model and two data acquisition cards.
Abstract: During the process of laser welding of an existent Nd:YAG laser manufacture system, some shortcomings might happen. The reason for such shortcomings was analyzed and the corresponding measures were proposed to overcome them. Experimental results show that by modifying the incidence angle of the laser beam, adding two side nozzles and so on, the laser welding quality and the life of the optical apparatus could be improved dramatically.
Abstract: Based on FEM (Finite Element Method) and CFD (Computational Fluid Dynamics), the effect of the number of damping plates and the distribution of damping orifice on the inner flow field and water spraying intensity distribution was studied. The water spraying intensity and it's deviation was compared among four kinds of headers, such as the header without damping plates, the header with one symmetric damping plate, the header with two symmetric damping plates, and the header with one non-symmetric damping plate. The result shows that the relative deviation of water spraying intensity of the header with two symmetric damping plates is the least one.
Abstract: A consolidated mathematical model and its computing method for a universal modeling column were proposed with Harmens state equation and the gas-liquid equilibrium theory of O2-Ar-N2 mixture. Based on them, a calculating model of an air separation unit (ASU) system was developed and the rectifying process was analyzed. The result of an application to No.5 ASU in BaoSteel made in APCI shows that the model and the computing method can accurately forecast the variation of operating parameters of ASU in the rectifying process.
Abstract: A hiding scheme for digital image commumication in Internet was presented based on a recent theory on generalized chaos synchronization (GCS). A 6-dimensional GCS system was constructed as the cipher device of the scheme. Theoretical analysis and a computing example show that the scheme has high fidelity and strong ability for preventing cipher break.
Abstract: Base on the statistical space mapping a self-learning method was proposed, which can overcome the shortcoming that the measured work-state data can not cover all the data space. Simulating experiment at results for the measured work-state data show its availability.
Abstract: Several large-scale behavior models of Internet security based on the research of complex systems and networks were reviewed. Beginning with the Power-Law distribution of Internet complex systems and the influence of this distribution on the modeling of network security, the quantitative model of epidemics and the qualitative relation between network robustness and complex network structure were discussed respectively. The research prospect in this field was predicted.
Abstract: A squeezed state of phonons and photons may have less quantum fluctuation than a coherent state. Compared to phonons or photons, the elementary excitations of the spin waves-magnons, are also bosons. Their Hamiltonian in a particle-number representation is similar to that of phonons or photons, and thus the squeezed state of magnons is possible to exist. The parameters characterizing the properties of materials can be calculated by measuring the quantum fluctuation of spin components in the laser field.
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
