Abstract: A conceptual framework of mine complex fields is proposed from the perspective of numerical modeling and visual simulation for geological and mining engineering systems. In view of the current trends towards the advancement of so-called digital mines using computation, information and communication technologies, the significance of developing the unified numerical modeling and integrated 3D visualization systems for mine complex fields composed of geological and mining objects and their attributes is emphasized. Oriented to the needs for developing the techniques and systems of digital mines, key issues in and major methods for numerical modeling and 3D visual simulation of mine complex fields are presented. Fitting into the framework and using the proposed methods, a prototype system with a Web-based approach for the numerical modeling and 3D visualization of geological drill holes, ore bodies and underground excavations is built to show the methodologies used in constructing the prototype and the usefulness of a unified numerical modeling and 3D visual simulation approach in addressing the problem of complex fields in underground mines.
Abstract: Based on the simplified plane shape, a new mining design and optimization method for recovering boundary coal-pillars, called arc-face mining method, was presented. Its advantages are as follows:easy to choose the related comprehensive auxiliary equipment, high recovery ratio and efficiency, and fitting the fully mechanized coal mining technology, even the sub-level longwall eaving face technology when the geologic condition is permitted. The key techniques include:developing a series of underground chambers along tailgate; in a chamber, storing some supports which will be added to the coming face-supports when the face advances near the chamber; canceling face-end supports and adopting a simple conveyer in order to add or remove supports quickly. Then, with the linear mathematics programming theory, the objective function of recovery efficiency and the constraint functions of safety and exploitation cost were established. It is concluded that the increased number of supports each time not only affects the number of underground chambers but also the efficiency. The optimization analysis also provides various optimal technology schemes with the principle of higher efficiency or lower cost.
Abstract: The prediction of coal and gas outburst was studied by analytic hierarchy process (AHP) and fuzzy comprehensive evaluation. In the prediction method, AHP was applied to confirm the weights of coal and gas outburst factors, the iudgment matrix of each factor was constructed by membership functions, and the prediction model of coal and gas outburst was established by the fuzzy comprehensive evaluation method. The prediction method was applied in risk type areas to forecast the coal and gas outburst quantitative intensity and the risk grade was divided in Pingdingshan typical mining area. The results show that the hierarchy process and fuzzy comprehensive evaluation method was available for forecasting the coal and gas outburst intensity.
Abstract: A hydraulic rotary drill instrumented with a drilling process monitoring system (DPM) was used for site investigation in Hong Kong weathered granite foundation engineering. The penetrating parameters such as effective thrust force, rotational speed, flushing pressure, penetrating rate and displacement of the bit were monitored in real time. A varied slope was defined as a significant index for identification of dominative and subsidiary interfaces in the granite site. The result from t-test shows that the confidence of the DPM in identification of the geotechnical interfaces is 99%. Besides, the analysis of variation of the penetrating parameters at the interfaces indicates that there are different fluctuations at the interfaces in the curves of the parameters with borehole depth. The response degree of effective thrust force and penetrating rate to the variation of rock strength at the interfaces is 81.82% alone.
Abstract: It was summarized that normal function, mountain function, triangle fuzzy function and trapezium function is usually used to simulate a continuous membership function during fuzzy evaluation of engineering rock mass, and their analytical equations were presented accordingly. The establishing method of four membership functions for concrete engineering index was researched through using the uniaxial compress strength of rock mass as an example during fuzzy classification of rock mass. The membership degree of a uniaxial compress strength value was calculated by the above-mentioned four membership functions. It was found that there was a bigger difference among the membership degrees calculated by different subject functions. Five main indexes that influence rock mass stability were picked out through analysis. Based on data of the surrounding rock of a tunnel, the membership degree values of the uniaxial compress strength of rock mass, RQD, integrality coefficient and soft coefficient were calculated respectively by three membership functions, and the membership degree of structure surface was decided, through a membership degree value table, for the rock mass of roadway. Some difference among the membership degree values of the rock mass of roadway was found when the membership functions that were used to calculate the membership degree were different. Yet the classification result of rock mass is identical under different membership degrees from different membership functions. The researched result testified equivalence, adaptability and correctness of a common membership function in fuzzy. The theoretic base of choice a subject function in fuzzy classification for rock mass was suggested.
Abstract: Formulations of the mixed cable-beam finite element method suitable for simulating a prestressed cable-beam structure were presented based on the incremental form of the virtual work principle, The attention is mainly paid to the interaction in constructing the prestressed cable-beam structure and the optimization of structure performance. Key point is to enforce initial displacements by adjusting the position of specified points in the structure. By using the proposed method, the whole process of constructing a prestressed cable-beam structure was simulated. The numerical results demonstrate that the proposed method is feasible.
Abstract: Cationic polymer CY-16 was synthesized to solve the problem of low-temperature oily wastewater. A series of evaluation tests with fresh wastewater demonstrated that, compared to other wastewater treatment chemicals often used in oilfields, CY-16 can achieve high efficiency both on oil removal and on suspended solids (SS) at extensively low cost. Under the condition of 15 mg·L-1 CY-16 + 5 mg·L-1 HPAM, water temperature 25℃, and sedimentation time 30 min, the final mass concentration of oil in treated wastewater decreased to no more than 10 mg·L-1, that of SS no more than 30 mg·L-1, and the median particle size of SS about 3.0μm.
Abstract: The 1kg crucible experiment was carried out in laboratory. The shape, size and composition of inclusions in medium-carbon high-sulphur structural steel were investigated. The results show that fusiform inclusions, which can improve the cutability of the steel, account for 68.11% in total inclusions, and the ratio of fusiform inclusions increases with increasing[Ca]/[S]. After calcium treatment the inclusions is very tiny, inclusions of less than 2.5 μm in size account for 76.05% and scattered in the matrix of the steel. The inclusions are mainly composed of (Mn, Ca)S sulfide and complex inclusions in which the core is calcium aluminate and the shell is sulfide. There are small amount of complex inclusions of calcium aluminate and calcium sulfide in the inclusions, too. The cutability of the ingot steel containing sulphur and calcium is better than that of middle carbon steel.
Abstract: The effect of cold roiling followed by annealing on the ultra-refinement of microstructure and the mechanical properties of eutectoid steel was investigated. The experimental results showed that the combination of cold roiling to 90% and annealing within the temperature range of 600-700℃ leads a duplex microstructure consisting of sub-micron ferritic grains and dispersive cementite particles. The distribution of cementite particle size displayed bimodal. In comparison with traditional spheroidizing treatment, the spheroidization time was significantly shortened and the microstructure markedly refined. This could be attributed to the formation of high-density dislocations and vacancies during cold deformation, which provided a high diffusion path of carbon atoms. The formation of dispersive distribution of fine cementite particles could be explained by the mechanism of dissolution-re-precipitation. It is also indicated that the present combined treatment of cold rolling and annealing results in pronounced increases in yield strength and ultimate strength, a slight decrease in tensile plasticity, and a relatively high yield ratio.
Abstract: The continuous cooling and isothermal transformation microstructure evolution in a low carbon Mo-Cu-Nb-B microalloying steel were investigated. It was found that acicular ferrite could be transformed independently in the intermediate temperature range of metastable austenite. Although multi intermediate transformation phases can be transformed during the continuous cooling, the fraction of phases, especially acicular ferrite, cannot be controlled. However, the fraction of acicular ferrite could be controlled by the step cooling process. The optimum amount of acicular ferrite divides the prior-austenite grains, resulting in multi-phase mierostrueture ultrafine.
Abstract: In order to accurately predict the remaining life of a gas pipeline which runs at different stress ratios, a new method of predicting the remaining life of flaw pipeline steels, namely, one-parameter fatigue life prediction method, at different stress ratios was proposed based on fatigue crack growth rate tests. The method considered the destruction effect created by different stress ratios during the running. The remaining life of X52 steel as an example was predicted under the condition of simulating the nature gas running (R=0.1 and R=0.6 by turns).
Abstract: The oxidation behavior and oxidation kinetics of FGH95 P/M alloy at different temperatures were investigated by TGA method, X-ray diffraction, SEM, and EDS analysis. The results showed that FGH95 alloy had good antioxidation characteristics in the temperature range of 800-1 000℃, and its oxidation kinetic curve obeyed a parabolic rule. When the temperature increased up to 1 100℃, the antioxidation property of FGH95 alloy decreased and its oxidation kinetic curve exhibited two parabolic segments. XRD, SEM, and EDS analysis indicated that the oxidant layer was mainly composed of Cr2O3 and TiO2, and little amount of NiCr2O4 was formed at 1100℃.
Abstract: The microalloying effect of niobium on the microstructure and magnetic properties of an Nd2Fe14B nanocrystal permanent magnet was investigated. The results show that niobium addition promotes the formation of amorphous phase and stabilizes the amorphous phase. During the annealing, precipitate phase after niobium adding restrains the growth of grains, uniforms the size of grains, and enhances the magnetic properties of the alloy. The optimum magnetic properties of Jr=0. 899 8 T, Hci=912.64 kA· m-1 and (BH)m=126.24 kJ·m-3 were obtained by annealing a melt-spun Nd12.3Fe80.7NbB6.0 amorphous ribbon at 550℃ for 10 min. But the magnetic properties decreased when the annealing temperature further increased.
Abstract: A set of experimental system of magneto-optic Kerr effect was set up mainly by using photo-elastic modulator and lock-in amplifier. The system was used to measure the magnetic properties of magnetic materials, especially for magnetic thin films. The longitudinal magneto-optical Kerr effect was used to investigate the magnetic properties and magnetic reversal. Transverse and longitudinal magnetic fields were applied in the plane of the samples in order to measure two perpendicular magnetization components in-plane. Co/Cu/Co sandwiches deposited on different substrates were prepared by high vacuum magnetron sputtering. From Kerr loops, the different of structure between buffer and Cu layer induced the difference of structure between Co down-layer and Co up-layer, which made the coercive force difference and magnetization reversal.
Abstract: The conception of multiphase flow and the two-phase flow models were introduced into the field of powder injection molding (PIM). The single-fluid model, two-fluid model and Eulerian-Lagrangain model for describing the powder-binder filling flow process were discussed. The characteristics of each model were briefly analyzed. Simulation results showed that the two-fluid model was fitter than the single-fluid model for describing the powder segregation, powder concentration and other special phenomena arising in PIM. Furthermore, the two-fluid model is easier to reach convergent than the Eulerian-Lagrangain model in simulating the PIM process.
Abstract: Titanium alloy parts were prepared by metal injection molding, binder was removed from the parts by solvent debinding process, and the brown parts were densified in vacuum atmosphere. The as-sintered specimens were treated through hot-isostatic pressure at 960℃ and 140 MPa, and titanium alloy compacts were annealed at 720-760℃ for 1-1.5 h. SEM observations showed that the titanium alloy had a uniform dial microstructure with many equiaxed a grains and a little β grains. XRD results indicated that Ti3Al phase was found in the alloy when the annealing temperature was higher than 800℃.
Abstract: Al5Ti1B master alloy refiner was prepared by the reaction of complex halide salts with molten aluminum at high temperature. The manufacture process and parameter range were regulated and the principle and course of the reaction were analyzed. As for the self-made master alloy, the Ti content reaches 4.64%, and B 0.84%. The self-manufactured product was compared by comprehensive evaluation with the products manufactured by KBM, LSM and some national organization. It is found that TiAl3 particles are less than 50 μm, and TiB2 less than 1μm in the Al5Ti1B master alloy developed by Tsinghua University and Baotou Aluminum Plant. Its refining performance is closed to KBM's Al5Ti1B. The self-manufactured product reaches the international standard in composition, microstructure and refinement effect.
Abstract: CaWO4 nano-powders were synthesized in micelles. Transmission electron microscopy (TEM), X -ray diffraction (XRD) and TG-DSC were utilized to characterize the shape, size and structure of the obtained products. The results show that low-dimensional CaWO4 nano-materials can be prepared through two different systems of surfactants (CTAB and OP-10/KH-B92). The formation mechanism of colloid and the growth mechanism of CaWO4 nano-powders were also discussed.
Abstract: By using a low temperature hydrothermal approach, well-aligned ZnO nanorod arrays were pre-pared on substrates, which were pre-treated with colloid pre-treating method in different growth periods of time. Scanning electron microscopy and X-ray diffraction spectroscopy were employed to study the morphology of ZnO nanorod arrays. Kinetic studies show that the first 8 h is the most important growth period, beyond which the nanorods nearly stop growing. During the first 8 h, the growth of width of ZnO nanorods contains two distinct steps:a fast step within the first 1.5 h, in which the nanorods tend to be short and wide, followed by a slow step, in which long rods with high aspect ratio are obtained. The length of ZnO nanorod arrays, which essentially represents the thickness of a homogeneous monolayer of the thin film, may be experimentally tailored to any required dimension of up to 2.4 μm at a growth rate of approximately 5.5 nm·min-1.
Abstract: A new 6DOF (six degree of freedom) two-axle automobile multi-body handling stability model was developed by the Roberson-Wittenburg method. In the model, a suspension system was taken into account. On this base, automobile handling stability was analyzed further by the Hurwitz theorem. The results show that an automobile with nice stable ride performance should follow two necessary conditions:the product of the square of rear bearing spring effective range and the rear suspension single side spring constant should be more than that of the square of front bearing spring effective range and the front suspension single side spring constant; the product of the mass hold by rear axle and the front tyre lateral stiffness should be more than the product of the mass hold by front axle and the rear tyre lateral stiffness. The second condition complements the deduced condition from a classic 2DOF automobile handling stability model.
Abstract: An SGA92150 semi-trailer frame's layout, longitudinal girders, crossgirders and joints were designed. The stress and deformation of the frame were calculated by using Ansys Workbench software with advanced method, and the force analysis and stress calculation of the longitudinal girder were carried out by using Matlab software with conventional method. The results show that the frame's strength and stiffness are enough to meet the design requirements.
Abstract: A kind of multi-hop and synchronous time-division protocol for wireless sensor networks based on equipment monitoring of metallurgy industry was proposed. The protocol employs self-organized and hierarchical topology. Cluster headers structure backbone network to forward sensor data to the sink node. Nodes in cluster transmit data in a lower radio power to the cluster header by multi-hop and time-division, they reduce power loss and transmission delay by synchronous sleeping-scheme. Application in an equipment monitoring system of metallurgy industry indicates that this protocol has the characteristic of strong extension, reliable transmission, small signal delay, and low power loss.
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
