Abstract: In order to divide "three zones" of the depressing zones overlying a goal accurately, the guideline to divide the "three zones" is presented:specifying the height of the rock stratum whose stress surpasses the yield or shear strength of itself as the upper bound of the fracture zone, while specifying the height of the rock stratum whose two-way tensile stress both surpasses the tensile strength of itself as the low bound of the fracture zone. FLAC software was used to determine the boundary of a coal mine that was validated by the effect of corresponding methane drainage. The result indicates that the division guideline is rational and useful. This method can be used generally to divide "three zones" of the depressing zones overlying a goaf.
Abstract: On basis of the investigation on engineering geological conditions, the process, pattern and features of karst water burst, as well as the mechanism of the water burst, were studied by means of laboratory test, numerical modeling, theoretical analysis and in-situ tests. The results showed that the karst water burst in a tunnel was a gradually developed process, which is influenced by water pressure, filling materials and plastic zpnes around the tunnel. Detailed technical measures were planned for different karst structural types and different geological modes in Yuanliangshan tunnel.
Abstract: According to the main multi-component foam drive mechanism and various physicochemical phenomena taking place in the EOR method, such as phase change, rheological property of foam phase, and foam vertical shallow, a series of mathematical models for describing the parameters of multi-component foam drive were established on the basis of foam drive mechanism and experimental results. The foam flowing rules in porous media were described in these models. The mathematical description of this complicated flow for multi-component foam drive was resolved. Numerical simulation results proved that the models could reveal the physical essence of porous flow.
Abstract: TiO2 nanometer particles were prepared by the sol-gel process and characterized by X-ray diffraction (XRD). Photocatalytic decomposition of acid black dyes was investigated in a cylinder type photoreactor made of quartz glass using a middle-pressure Hg lamp as the light source, The effects of the calcination temperature, flow rate of air, pH of solution and illumination time on the photodegradation rate of acid black dyes were discussed. The results showed that the calcination temperature greatly enhanced the photocatalytic property of TiO2, Calcining the powders in air at 400℃ for 3 h, the broad peaks of anatase type on the curves of XRD patterns of TiO2 appeared. Calcining the powders in air at 500℃ for 3 h, all crystal particles in TiO2 changed the structure of anatase type, and the content of rutile type increased gradually along with the calcination temperature rising. Calcining the powders in air at 750℃ for 3 h, all crystal particles in TiO2 turned into the structure of rutile type. However, the crystal type of TiO2 did not change along with the calcination time prolonging at the same temperature. The photocatalytic activity of TiO2 was the highest while calcining TiO2 at 600℃ for 3 h. Under the optimum conditions, the photocatalytic degradation rate of acid black dyes reached 100% with the illumination time of 140 min.
Abstract: The commercial FEM analysis software ANSYS was used to simulate the induction heating process and cooling process of a special shape chassis part made of 0.45% C steel. Combining with the temperature variation curve by simulation and the CCT curve of 0.45% C steel, the microstructure inside the workpiece was predicted after it was cooled in air. The result showed that the simulated data of temperature field and microstructure agree well with the experimental ones in industrial condition.
Abstract: The tensile mechanical properties of two industrial TRIP steels, K(0.091% C-1.456% Si-1.061% Mn) and B(0. 134% C-1. 525% Si-1.226% Mn), at high strain rate were investigated with a selfdesigned pneumatically actuating tensile impact bar-bar tester and compared to the quasistatic tensile behavior. The results showed that their tensile properties at room temperature exhibit consistent trends and are far more sensitive to strain-rate in dynamic tension than in static mode. Because the stable retained austenite in TRIP steels transformed to martensite during tensile test and the materials exhibited excellent transformation induced plasticity, the plastic deformation behaviors were evidently improved.
Abstract: Strong environment brittleness and intrinsic brittleness of Fe-Si system alloys caused by ordered phases result in difficulties in machining and heat machining. Based on the principle of increasing the plasticity of materials by extruding, the warm extrusion process of Fe-Si system alloys was investigated systematically. The warm extrusion blooming technology was used to realize the low temperature rolling of an Fe3Si-base alloy. All parameters for the extrusion process were gained by experiment.
Abstract: The effect of forming temperature, injection pressure and piston velocity on the filling ability of semi-solid A356 aluminum alloy slurry were investigated. It is shown that a higher forming temperature helps to the good filling ability, and injection pressure and piston velocity have important effect on the filling ability. The higher the injection pressure, or the higher the piston velocity, the better the filling ability is. Besides the thickness of a sample piece has great effect on the filling ability, and the thicker the sample piece, the better the filling ability. The results also show that the mierostructure distribution of A356 semisolid alloy is homogeneous, which is helpful to high quality castings.
Abstract: Supersaturated Al-Zn-Mg-Cu-Mn alloy powder was made using the spray and high energy ball milling method, and XRD was used to investigate the decomposition process of the supersaturated alloy. The results showed that the balanced phase precipitated from the supersaturated alloy was η phase (MgZn2) when the decomposition temperature was below 350℃, and no balance or metastable phases containing manganese were detected by the XRD method. When the decomposition temperature was 350℃ for a long time, or above 350℃, there were two phases precipitated from the supersaturated alloy. One was the balanced η phase(MgZn2), and the other was Al6Mn, which was directly precipitated from the alloy, but not transformed from any metastable phase of manganese.
Abstract: Preparation of a nanocrystalline Al-Zn-Mg-Cu alloy by mechanically milling at cryogenic temperature (cryomilling) was studied. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and differential scanning calorimeter (DSC) were used to investigate the effect of cryomilling process on the grain size, the microstrain, the phase transformations in solid and the thermal stability of this alloy. With increasing milling time, the grain size of the alloy decreased sharply. The grain size is 45 nm cryomilled for 10 h. The more the milling time, the greater the microstrain of the alloy is. During the cryomilling, MgZn2 gradually disappeared and super-saturated to α-Al, and only a little MgZn2 remained after 10 h cryomilling within the precision of the X-ray method. The grain of the Al-Zn-Mg-Cu alloy growed very slowly when it was heated under 709 K, which showed that the nanocrystalline Al-Zn-Mg-Cu powders have high thermal stability.
Abstract: Al2O3/WC-10Co/ZrO2 cermets were prepared by a hot-pressing process by using WC 10Co nanocomposite powder, Y2O3 stabilized nanocrystalline ZrO2 powder and submicron Al2O3 powder. The influences of sintering temperature on the microstructure, grain size and properties were investigated according to the density, fracture toughness, Rockwell A hardness (HRA), hysteresis loops and scanning electron microscopy (SEM) micrographs of fractured surfaces of the specimens. The results show that the composite powders (WC-10Co (50%)/Al2O3(40%)/ZrO2(10%)) after being high-energy ball-milled for 48 h was hot-pressing sintered at 1450℃ then submicron Al2O3/WC-10Co/ZrO2 cermets with an average grain size of less than 1μm and better properties of 97.5% in relative density, 7. 446 8 Ma·m1/2 in fracture toughness, HRA 94.0 is achieved.
Abstract: An MoSi2 heating element was prepared by powder metallurgy with MoSi2 powder synthesized by self-propagating high temperature synthesis (SHS) and ceramic compound as the starting materials. Its microstructure and properties were tested by XRD and SEM with EDS. The results indicated that MoSi2 was the major phase accompanied by small fraction of Mo5Si3 and ceramic compound. Adding ceramic compound could obviously activate the sintering of MoSi2 and reduce its sintering temperature and retard the over growth of grains. The hardness and fracture toughness were also improved. A glass scale with high content SiO2 and less MgO, CaO, Na2O, Al2O3 was produced by oxidation at high temperature of electric current.
Abstract: The new SmartCrown profile and flatness control technology was first adopted in a wide strip tandem cold rolling mill. Through studying on the function structure and characteristic parameters, this paper deduced a way to determine the SmartCrown work roll contour. The effect of roll contour characteristic parameters on the roll gap profile was further analyzed. This study is important to the grind of the work roll contour, the control of strip shape and the spread of SmartCrown technology.
Abstract: In order to hold up the thin water film formed by cooling process on the surface of a steel plate, an air-seal device is build up at the every row of the air-spray device, which leads the thin water film to flow away from the edge of the plate and gets the flat plate. Some parameters such as volume flux, nozzle width, outlet velocity, the height between nozzle and plate, and single nozzle hold-up water velocity were studied. The reasonable values were chosen, the cost was reduced, and the optimized which help to choose reasonable values, reduce the cost, and then get the optimum hold-up water effect was obtained.
Abstract: The carbon amount of unused pulverized coal in dust and sludge during the industrial experiment of Changcun coal in Baosteel's 1# blast furnace (BF) was investigated by microscopic and chemical analysis. The carbon amounts of s udge and dust and of unused coal were determined in the condition that the mass fraction of Changcun coal was about 20%-40%. culated in different conditions of pulverized coal injection in The utilization ratio of pulverized coal was cal Baosteel's BF.
Abstract: A transient one-dimensional coupled conduction-radiation heat transfer model was developed for thermal diffusivity measurement of semi-transparent materials by the flash method. On the basis of the control volume method, the discrete ordinate method (DOM) was used to solve the radiation heat transfer equation of the model. It showed that the numerical results were agreed well with those by the thermal quadrupoles method (TQM). DOM was a little bit time-consuming but was available for a non-linear physical property problem. Only a constant physical property problem can TQM solved, although it is faster than DOM. The sample's backside temperature response was analyzed for various sample thickness, absorption coefficient, radiative boundary condition and heat loss.
Abstract: To predict and control the yield strength, tensile strength, and elongation of hot-rolled steel strips, a quality model, which could predict the mechanical properties of hot-rolled steel strips with technological parameters, and a reverse quality control model, which could optimize technological parameters with the mechanical properties, were established by applying the technology of artificial neural network. With the quality prediction model it was proved that the value of yield strength decrease with the increase of coiling temperature. Based on this, the mechanical properties of hot-rolled steel strips could be controlled through the real time regulation of coiling temperature to meet production requirements.
Abstract: Multi-stage production planning plays an important role in improving the production rate and energy saving in modern manufacturing industry. Based on the analysis of production flow and planning of an electric resistance welding (ERW) manufacturing enterprise, this paper proposes an advanced/delayed punishment mathematical model of multistage production planning. A local optimal solution for it is obtained by the real number-coding genetic algorithm. Simulation results indicate that the model and algorithm are feasible and efficacious. The presented solution has well applied to practical ERW production planning.
Abstract: A class of bilevel multl-objective programming was converted into the problem of equivalent single-level multi-objective programming. Then a new chaos genetic optimization algorithm was presented by using the inversion property of genetic algorithm and the ergodic property of chaos optimization method and combining with the exact l1 penalty function. The local search ability and search accuracy of genetic algorithm were improved. The solving accuracy and credibility became high. An actual calculated example showed that the algorithm is effective and efficient.
Abstract: To overcome the difficulty of complex background in mining machine fault diagnosis, a fault diagnosis system based on independent component analysis (ICA) and vector quantization (VQ) was developed. A fault sound ICA model was presented to get the fault sound feature bases with ICA algorithms in extracting nature images and continuous speech features. One ICA separated the sounds from different parts of the machine and the other extracted the feature basis of fault sound. The coefficients of the basis were used in designing codebooks. The diagnosis accuracy of this system is 96.8% in the experiment with the realistic mine machine fault data, so the ICA-VQ is a high efficient fault diagnosis system.
Abstract: By using the large-scale system technique and Lyapunov second method, this paper studies a class of Lurie indirect control large-scale systems, and builds up a relationship between this kind of systems and the stability of the reduced dimensionality in accordance with the Metzler matrix. The sufficient conditions of the absolute stability about this Lurie indirect control system are obtained. The presented method is simple, and its superiority is shown by an example.
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
