Abstract: Both the stress environment and the size of underground excavation influence the stability of the mining face and the slope. Numerical analysis of FLAC3D was used to reveal the stress environment arouiad the excavation in the slope, discuss the strata movement, stress distribution and failure mechanism, and analyze the stability of the slope affected by underground excavation. The results show that local curved failure zones may become worse during underground mining under the disturbed slope, but the stability of the slope as a whole will not be changed. For the unloading effect, the arching mechanism in the roof strata is weakened, and the probability of catastrophic collapse exists in roof strata above the mining zone.
Abstract: Through GPS monitoring in Shuichang iron mine, the location of monitoring points and the optimizing design of monitoring network were discussed. Based on 9 phases monitoring data of 6 monitoring points and field monitoring experience, rose diagrams in level displacement direction were mapped. The monitored result accords with the actual state of the mine. Compared with other ordinary monitoring instruments, GPS monitoring can satisfy the precision of an open pit mine's slope deformation monitoring completely.
Abstract: To study the feasibility of a glass-fiber reinforced cement (GRC) composite shear wall system with stay-in-place mould, this paper tested the bonding behavior between GRC plate and concrete, and the experimental data were analyzed to show a better bonding property. The test on the mechanical properties of the GRC plate was also carried out and showed that it has a good bending strength. It is concluded that the composite shear wall system with GRC stay-in-place mould is feasible and available.
Abstract: There were three ways to reduce metal oxides by metal reducing microorganisms:direct contact, electron shuttling and chelation of insoluble metal oxides. A microbial fuel cell by Geobacter metallireducens was used to investigate the influence of the three paths on the rate of dissimilatory iron reduction. The results indicate that in the process of dissimilatory metal reduction, NTA and AQDS can accelerate the speed of ferric oxides reduction and magnetite generation in the initial stage, but magnetite production prevents further iron reduction. Direct contact is a very important way, and the biomembrane formed by adsorption for long time is a critical factor for reduction. Electron shuttling plays a less important role after most of mineral oxides surfaces have been enclosed by microorganisms.
Abstract: 20MnSi steel with a submicrometer ferrite grain size of about 0.20μm was manufactured by four passes of equal channel angular pressing via route C at room temperature, and the effect of annealing temperature on the ECAP deformation microstructure was examined. The results show that with the annealing temperature increased, the ECAP deformed microstructure is evolved into recrystallized grains insitu. At annealing temperatures of 300-500℃ for 1 h, the submicrometer ferrite microstructure is relatively stable with negligible grain growth. At annealing temperatures above 500℃, the ferrite grain starts to grow significantly, and there is an average grain size of about 8μm after annealing at 650℃ for 1 h. The cementite in the pearlite by ECAP has a stronger ability of spheroidization at a lower annealing temperature.
Abstract: The aging hardening behavior of low carbon bainitic steels with Cu, Nb, Cr, and Mo was determined, and creep tests for various steels were conducted on a Gleeble-1500 thermal simulator. Optical microscope and TEM were employed to study the microstructure and precipitates of the steels respectively. The results indicate that there is an obvious aging hardening behavior during the aging of copper containing steels; a plateau occurs on the creep curve at different temperatures, which results from the precipitation. The occurrence of the plateau means the start of the precipitation process, and when the precipitation finishes the plateau disappears.
Abstract: The effect of heat treatment on the magnetostrictive properties of a (110)-oriented polycrystal Fe83Ga17 alloy was investigated. It was found that the saturation magnetostrictive strain of the quenched Fe83Ga17 alloy exceeded 300×10-6 under a compressive stress of 25 MPa. The results of Neutron diffraction and differential thermal analysis confirmed that slow cooling leads to the change of phase structure which resuits in the change of magnetostrictive strain. The increase in magnetostrictive strain of the Fe83Ga17 alloy treated by quenching is explained as that the long-range DO3 is suppressed.
Abstract: The isothermal compression deformation behavior of a modified cobalt alloy was investigated at temperatures from 850 to 1 150 12 with Gleeble-1500 simulation machine. The experimental results show that the alloy has excellent high-temperature mechanical properties. Its maximum flow stress at 850 12 is in the range of 360-475 MPa when the strain rate is between 0. 0021 and 2.1 s-1. The flow stress of the alloy during high temperature deformation can be described by Zener-Hollomon parameter.
The temperature distribution in a crystallizer has important influence on the position and shape of solid-liquid interface during continuous unidirectional solidification. Based on the established three-dimensional physical model, simplified terms, specified material parameters in thermal and physical properties, boundary conditions, and the calculation method of heat convection of cooling water, the numerical simulation and analysis on steady-state temperature field for continuous unidirectional solidification of NiTi shape memory alloy wire billets were proceeded under the condition of different combined parameters using ANSYS finite-element software. The results indicate that the NiTi shape memory alloy completely solidifies in the crystallizer and the solid-liquid interface presents flat under the given model and various parameters, which meet the basic requirement of continuous unidirectional solidification.
Abstract: Using temperature optimization process and embedded atom method (EAM), the equilibrium melting point of Cu was calculated under the constant-temperature and pressure molecular dynamics. The influence of time step on the calculated results was also studied. The simulation shows that the shorter the time step is, the smaller the difference between the calculated melting point and the experimental is. When the time step is below 0.05 fs, the decreasing of time step has no effect on the calculated melting point in the range of calculation precision.
Abstract: A material with low density and high strength was made by filling great amount of hollow glass micro-beads in bulk material epoxy resin, m-phenylenediamine (MPD) and 4, 4'-diaminodiphe-nylsulfone-(DDS) were chosen as the optimal modifier. The consistence between polymer and hollow glass beads and the mixing quantity of hollow glass beads were increased by modifying the surface of hollow glass beads. Through system optimization on all the factors influencing the surface treatment, the deep-sea buoyancy material was fabricated with a density of 0.61-0.75 g℃m-3, a compression strength of 40-68.96 MPa and a less water absorption rate.
Abstract: About 80% of particles in sludge were smaller than 149 μm in diameter at 1# BF in Baosteel of China and the particle distribution was composed of two normal distribution curves. While approximately 65% of particles in dust were about 74-297 μm in diameter and the particle distribution was composed of three normal distribution curves. Different microstructures of unused pulverized coal and coke in dust were found through petrographic microscopic analysis. According to the utilized carbon degree of unused pulverized coal and coke, an equation of the ratio of unused pulverized coal to coke in Changcun industrial experiment dust was proposed by means of the microscopic analysis results.
Abstract: Gas flow in a magnesium reduction furnace was numerically simulated with the comprehensive CFX software, and the effect of the gas flow on heat transfer process in the magnesium reduction furnace was studied. Based on the simulation, some practical measures were put forward to enhance the heat efficiency of Pidgeon process. In the measures the improvement of flow field inside the furnace is very important.
Abstract: This paper deduced the involute gear total tooth profile equations of unsymmetric teeth with double pressure angles, proposed the calculation formulas of coordinates and load angle at the upper and lower points of single and double teeth mesh areas, and programmed the relevant parametric programs. Compared with a standard involute gear, the unsymmetric involute gear could efficiently improve the tooth root bending strength by finite element analysis. Considering the time-variant mesh stiffness, the calculated results demonstrated the change of tooth root bending stress in one engagement period.
Abstract: A three-dimensional mathematical model of internal flow field in a soil bore-enlarged nozzle was established with the CFD software. Using the standard κ-ε turbulent model, the internal flow field in the nozzle was simulated and the influence of nozzle parameters on the velocity contour, pressure contour and outlet axial velocity of the flow field was studied. The results show that the diffuse angle and divergent cone length of the nozzle influence the internal flow field more and the effect of the cylindrical segment length is relatively less. The optimum values of all these parameters were proved to exist. Simulated results close to indoor test results, which accounts for the relationship between the internal flow field distribution in the nozzle and the soil impact effect of water jet.
Abstract: Numerical simulation with the standard k -ε model was performed to study single-phase convective heat transfer at the impinging zone of non-immersed slot jet. The factors considered were jet velocity, spacing of nozzle-to-impinging plate (height), slot width, angle between jet direction and plate, temperatures of impinged plate and water (liquid) from the slot nozzle. The results show that jet velocity is the most remarkable factor influencing heat transfer at the impinging zone, and other factors such as water temperature and slot width are also non-negligible. The angle between jet direction and impinging plate only influences the distribution of local convective heat transfer coefficient.
Abstract: A vehicle detector with an anisotropic magnetoresistive (AMR) sensor was developed. The vehicle detector consisted of a three-axis AMR sensor and related signal processing circuit. When a vehicle was moving over the detector, the surrounding magnetic field changed due to vehicle disturbance, and the output of the three-axis AMR sensor changed accordingly. Whether a vehicle was present or not could be judged based on the AMR sensor's output. The detector's characteristic was tested. When the vehicle being detected was moving over the detector along different directions (south-north, east-west), the output changes were different. The results show that this detector can realize the function of vehicle detection.
Abstract: It is difficuh to extract crack defects front a defect image by traditional detection techniques, for the image of surface crack defects on a medium plate is influenced greatly by background nolo- and oxidized scale. Morphological wavelet, which combines the advantages of wavelet decomposition with mathemarital morphology, was introduced to decompose the defect image and detect calastrophe signals. According to the similar linear character of crack defects irn shape, the crack defects can he accurately extracted from the image. Experimental results sit, show that the morphological wavelet transform presented here is more effective than other techniques for the detection of surface crack defects of a medium heavy plate.
Abstract: To solve the problem of uncertain time delay in networked control systems (NCS), the uncertain of time delay was converted to the uncertainty of parameter matrixes, and the model of NCS was simplified as an uncertain discrete model with time delay. The guaranteed cost control problem for NCS was translated to a robust guaranteed cost control problem for an uncertainty discrete system with time delay based on the above model. Lyapunov theory and linear matrix inequality (LMI) were applied to prove the sufficient condition of guaranteed cost control for NCS was equivalent to solving a LMI by a static state feedback. Simulation results show effectiveness of the proposed control method.
Abstract: A new ear recognition method combining independent component analysis (ICA) and BP neural network was proposed. The FastICA algorithm was used to derive independent basic images and projection vectors out of ear images, and three-layer BP neural network was used to classify ears. The local features extraction of ICA and the adaptability of BP neural network were combined reasonably. The robustness of the system was enhanced. Experiment results show that the ear recognition rate of the ICA-BP method is improved obviously.
Abstract: In order to deal with attributes reduction, one of the major problems in rough set theory, an attributes reduction algorithm was proposed based on scan vector, and a new conception of discernible vector was defined by which the information table can be transformed into discernible vector sets. Depending on the structural feature of the discernible vector, a plus rule for the discernible vector sets was defined, and a scan vector with concise structure but representing the information table can be obtained through scanning the discernible vector just one time. The item of attribute frequency in the scan vector was taken as heuristic information to improve the efficiency of attributes reduction. An illustration and experimental results indicate that the method proposed is much more effective.
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
