Abstract: Mining the ore in pillars above the mine-out area comes down to the security of production, mining methods and putting in practice. In order to evaluate the stability of top terrane and wall rock precisely, the stress relief method by overcoring was used to measure the in-situ stresses in Sanshandao Gold Mine of China. In this measuring, the technique of improved hollow inclusion cells was adopted which can actualize complete temperature compensation. From the measuring results, a distribution model of in-situ stress was established, and the in-situ stress distribution rule of Sanshandao Gold Mine was analyzed. The results show that the in-situ stress field of Sanshandao orea relies mainly on horizotal stress and accords with the crustal movement rules of China.
Abstract: In order to study the damage of overburden rock and the surface subsidence caused by water-control mining at Lingxin Coal Mine, the in-situ stress distribution law, the damage height and crack height, the overburden rock displacement law and the ground pressure law were abtained by means of engineering geological investigation, color bore-bole TV inspecting, leakage monitoring in drilling fluid, simulation experiment, numerical computing, in-situ stress measurement and subsidence measurement. The result shows that safe mining at L3414 working face underneath the Xitian River and environmental protection can be implemented ultimately.
Abstract: Ground penetrating radar (GPR) surveys were conducted in rock mass structure detection and advanced geological prediction for 255 roadway in Linglong Gold Mine of China. The targets of the GPR surveys were to abtain the near-surface mined-out area features associated with dynamically induced liquefaction and disturbances. The GPR survey results using a 250 MHz antenna at the sites of some examples show that GPR is useful to locate subsurface features in the mined-out area for hazard assessment.
Abstract: Traditional methods for modeling mineral deposits involve two independent parts, i.e., geometric modeling and attribute computing. Based upon volume visualization, an approach for the modeling of mineral deposits was presented to integrate the computation of deposit attributes into the modeling of deposit geometry, including the preprocessing of volume data, the three-dimensional rendering of mineral deposits and the calculating of deposit attributes. Three types of volume visualization models for mineral deposits are introduced and a case study is described. It is concluded that this approach can improve the modeling of mineral deposits in terms of the integration of visual display and attribute analysis.
Abstract: Bioleaching experiments on the open stripe nickel ore in Jinchuan Mine of China were carried out. It is demonstrated that the leaching of nickel is combined bio-direct action with bio-indirect action. Thiobacillus ferrooxidans (TF) chemistry behavior difference between TF living in the culture medium and that living on the surface of the ore is based on the protein membrane which grows on the surface of TF. The Ni leaching rate and the oxidative activity of TF are influenced by the growth rate of TF adhered on the solid phase and free in the liquid phase, mineral mass density, Fe3+ concentration and pH consistency. Add on-ferric ion can interfere in the bacteria oxidative and inhibit the leaching of Ni, which lead to the formation of sediment on the surface of the mineral and reduce the leaching rate of Ni.
Abstract: Based on the analysis of developmental characters of modern EAF technology in the past forty years, it is pointed out that modern EAF technology has developed around the goal of shortening tap-to-tap time to meet the rapid continuous casting rhythm and the integrated control theory of modern EAF melting tap-to-tap time is proposed. The effective EAF steelmaking technologies including hot metal charging technology and the application of the theory to EAF steel production in China are introduced. The integrated control theory of modern EAF melting tap to tap time has directed and promoted the development of iron and steel metallurgy and EAF steel production in China.
Abstract: The clogs on the submerged entry nozzle of type 304 and 321 stainless steels were investigated, and the mechanisms of clogging were discussed. The results indicated that deposits on the nozzle in type 304 stainless steel consists of Al2O3, MgO·Al2O3 and some metal. Because of the thin deposits, the casting was not affected obviously and could be improved by controlling [Al] < 0.01 %. There are two kinds of clogging, namely TiN-type and CaO·TiO2-type clogging, in the casting of type 321 stainless steel. TiN-type clogging consists of a lot of TiN inclusions and some metal, and could be improved by [Ti%]·[N%]×103 < 3.5 and [Al] < 0.01% in liquid. CaO·TiO2 type clogging consists of CaO-TiO2-MgO-Al2O3 and a lot of metal, and could be improved obviously by reducing the amount of CaO-TiO2-MgO-Al2O3 inclusions in molten steel.
Abstract: A technique for treating 16 Mn steel with high-La mischmetal additives was proposed. The effect of the additives on the inclusion and mechanical properties of 16Mn steel was investigated and compared with that of Ce-rich additives. It is shown that high-La rare earth additives play a role in modifying inclusion and improving properties of the steel. The optimum effect of RE occurs when the mass ratio of RE/S=2.5. The high-La mischmetal can replace Ce-rich mischmetal with RE additives for treating 16 Mn steel.
Abstract: In order to study the effect of vanadium addition on the microstructure and properties of medium chromium white cast iron, the microstructure and composition of samples made of the cast iron were analyzed by SEM and EDS. The impact energy and Rockwell hardness of the samples were tested. The results indicate that with an increase in vanadium content, the microstructure of medium chromium white cast iron becomes finer and the impact energy values are enhanced. When the mass fraction of vanadium exceeds 4%, a large amount of VC precipitates occur, which make the cast iron have potentially favorable wear resistance.
Abstract: The hydride generation of Pb from alkaline solution by atomic absorption spectrometry was studied. The K3Fe(CN)6 and sodium tartaric were used as oxidant and coordinate agent, and the mass concentrations of NaOH and KBH4 in the test solution were 3.6 g/L and 1 g/L respectively. The test solution was acidified with 12.5 g/L oxalic acid to generate the hydride of Pb. The sensitivity and detection limit were 0.073 ng/ mL and 0.20 ng/ mL, respectively. The allowable values of Fe, Co, Ni in the test solution of 25 mL were 30, 3, 3 mg with this system, and it was enough to determine Pb in iron and steel without seperation of the matrix. The method was experimentally used to determine Pb in iron and steel with a satisfactory result.
Abstract: Nanocrystalline WC-10Co composite powders were sintered by hot-press sintering at 1360℃. The influence of 1.0% VC and 1.0% Cr3C2 (mass fraction) growth inhibitors on the sintering properties of the composite powders was investigated according to the transverse rupture strength (TRS), Rockwell A hardness (HRA) and the scanning electron microscopy (SEM) micrographs of the fractured surfaces of specimens. The result shows that the inhibiting grains growth effect of 1.0% VC is better than that of 1.0% Cr3C2. When nanocrystalline WC-10Co composite powders doped by 1.0%VC or 1.0% Cr3C2 (mass fraction) are sintered at 1360℃, ultrafine WC-10Co cemented carbide with an average grain size of less than 300 nm and better properties are achieved.
Abstract: After comparing the electrochemical impedance of titanium alloy TC4 with different tension strains, it is considered that the corrosion rate of TC4 with high strain would be more easily affected by the frequency of corrosive current than that without strain. According to traditional stress corrosion mechanism, the stress corrosion crack was in a state of open and close alternately, and from this it made AC current. So the crack propagation would be affected by the frequency of the AC current, and when the frequency was 50 Hz, the corrosion rate was estimated to increase at least 10 times. It is concluded that in stress corrosion process the rate of crack initiation and propagation would be determined by the frequency of AC current on metal/solution interface.
Abstract: Compared with painted carbon steel, the degradation of the paint finishing system of magnesium alloys in salt spray was studied by Electrochemical Impedance Spectroscopy (EIS). The result showed that whether based on chromate conversion coating or not, the electrode process of the paint system on magnesium alloys was more inclined to be controlled by diffusion than that on carbon steel, and the slop of the diffusion line was less than 1. The possible reason was given. It was proved that inductance unit existed in the finishing system with chromate conversion coating. The coating resistance and capacitance were calculated with all EIS data. The finishing system with chromate conversion coating absorbed much more water and corroded more severely than that without chromate conversion coating. The calculated values were not fixed but varied, and the more severely the coating degraded, the more widely the value ranged.
Abstract: The mechanochemical surface modification of two-dimension sericite flaky nano-materials was investigated through the grinding of a stirred mill. With titanite as the surface modification agent of sericite, the effects of the dosage of modification agent, massic ratio of midium/sericite, density of slurry, grinding time, temperature and pH value on the surface modification were analyzed. The properties of polypropylene (PP) filled with the modified filler were tested. The result shows that it is feasible to modificate two-dimension sericite flaky nano-materials mechnochemically and the composite materials of PP filled with the modified filler have a better capacity of resisting ultraviolet radiation.
Abstract: The alite-sulphoaluminate clinker was made by use of raw materials got from Qinghai Province, China. The clinker combines the advantages of Portland cement clinker and sulphoaluminate cement clinker and can excite the activity of mineral admixtures such as fly ash and slag more easily because of its alkaline and sulfate dual activation. Based on those properties of the clinker, a kind of compound cement, high-activity alite-sulphoaluminate cement (HAASC) was prescribed. By means of microstructural analyses, the hydration reaction mechanism of HA-ASC was discussed, and the principle of dominant complementation effect in a complex cementitious system was stated. It is proved that the concentration of Ca(OH)2 in hardened HAASC paste is much lower than that in ordinary Portland cement paste, and its long-term strength is improved with an appropriate crystal/gel ratio because of its particular mineral composition of clinker and dual activation to slag and fly ash, however its early strength is somewhat lower.
Abstract: Based on the slaking curve and thermo-gravimetric curve of calcium lime, the rational cold compression molding techniques of calcium carbide were given. According to the properties of raw materials and the requirement to binding agent, ZJ-type composite binding agent, which was mainly mixed with organic and inorganic binding agent, was developed and its performance and binding mechanism were analyzed. In order to meet the need of production hi practice, the proper molding water content, pressure and curing age were determined by experiment and analysis.
Abstract: The permeation experiments of L-phenylalanine and L-aspartic acid aqueous solution were carried out with NTR7450 membrane. When pH=5~8 the rejections to L-phenylalanine and L-aspartic acid by NTR7450 membrane are about 0 and 90%, respectively. The concentration and separation process of phenylalanine and aspartic acid solution was simulated. The results showed that L-phenylalanine and L-aspartic acid can be separated satisfactorily by adjusting the pH value.
Abstract: Recent studies on two phase flows in gas-solid fluidized beds were retrospected, and the development in nonlinear mechanism studies was outlined. The chaos studies indicate that fluidized bed systems are determinacy chaos systems and the results of the dissipative structure theory attribute fluidized bed systems to non-equilibrium thermodynamic ones. The analyses of stochastic force on fluidized bed systems apply the stochastic theory to flowing mechanism and studies of bubble distribution, and redound to open out the inside nonlinear mechanism and characteristic of fluidized beds.
Abstract: Based on the structure feature of xonotlite-type micro-pore calcium silicate, micro-pore calcium silicate is simplified as porous media with hollow spherical agglomerates, and two element models, point-contact empty spherical shell model and area-contact empty cubic model, are developed. Through applied one-dimensional heat conduction in the cell, the models for calculation of the effective thermal conductivity of micro-pore calcium silicate are derived. As compared with the experimental data of calcium silicate, the results show that the calculating results by the models have better agreement with those by experiment, and the models can be used to approximately calculate the effective thermal conductivity of porous media which have similar structure feature with micro-pore calcium silicate. In addition, the effect of temperature and contact parameter on the effective conductivity is analyzed, and it implies that the extent of contact between the hollow spherical agglomerates in xonotlite-type calcium silicate is not very high.
Abstract: The thermal contour on-line prediction of work rolls is one of the difficult problems in strip shape control. A theoretical model was built to calculate the on-line work roll's thermal contour by using the one-dimension finite difference method and used to calculate the temperature field and thermal contour at any tune in rolling and after rolling. The result indicates that the computation of this model is rapid and accurate in simulation and online application. This model suits to be used in the process of strip shape on-line control.
Abstract: Based on geometrical models during the whole process of forming inside right-angled step in cross wedge rolling which were proposed in past years, an effective geometrical model was built through generally analyzing the geometrical influencing factors of forming inside right-angled step. Mathematic representations of the surfaces and turn radius of the part in the whole process of rolling were derived.
Abstract: A method of 3-D defection for surface defects is presented with a light beam emitted by a linear laser, which is projected on the surface of steel plates vertically, and the surface images of steel plates are captured by an area-scan camera. Midpoint thinning is applied, and laser lines are extracted according to stabilization points. Partitioning calibration is proposed for calibration of the camera, and space coordinates of the laser lines are calculated based on the concept of space revert. Referential planes for depth calculation of defects are selected by projection scanning. The method was examined with defect samples, and the result of depth calculation was very close to experimental value.
Abstract: The control method of a rotary actuator, which is the executive organ of a pneumatic manipulator, was investigated. According to the stability theory, an optimal index function was constructed, and the adjustive law which could ensure the error between the system's output and the expected value tending to zero was deduced based on the index function. Through simulation and experiment, the influence of adjustive parameters on the dynamic performance of the system was also analyzed. The experimental result show that the parameter adjuster based on the stability theory can not only make the expected output of system tracking accurately, but also keep the stability of the closed-loop system.
Abstract: Artificial life and artificial intelligence are combined and applied to computer animation. In the computer animation created by artificial life, some behaviors of artificial life in virtual environment are pre-defined by programmers, and some are nondeterministic arise at random. Artificial fish is researched as an example, and a cognitive model of the nondeterministic behaviors of intelligent life is presented. The subset searching mechanism is used to improve the searching efficiency. It is shown by the simulation example that with help of the cognitive model, intelligent life is capable of handling some nondeterministic events.
Abstract: The basic theorem for constructing a kind of 4-dimensional chaotic system is presented based on the feedback control method under discontinuous state. Chaotification of a kind of simple 4-dimensional linear differential system is achieved. Numeric simulations verify the correctness of the theorem.
Abstract: The Lorenz chaos system was applied to the digital image encryption based on the thought of the higher secrecy of a three-dimension chaos system. Firstly, it carried out pretreatment to a real chaos sequence produced by the system. Secondly, the index matrix of pixel permutation was structured directly by this real chaos sequence. Finally, digital image encryption was realized in the space domain. The results of analysis and simulation show that pretreating the real chaos sequence has the stronger pseudo-random, the better autocorrelation and mutual correlation characteristic. Additionally, the bigger secret-key space of the three-dimension chaos system, the stronger the algorithm can be against decryption attack. Three outputs of the system not only can realize the parallel encryption of three or more images, but also increase the more encryption efficiency of the algorithm.
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
