Abstract: The distribution of oxygen concenlration and the velocity of air flow in a mined-out area were determined by numerically simulating the flow field. With the simulated results together with the duration and threshold of coal spontaneous combustion obtained from experiments, the spontaneous combustion dangerous zone was partitioned into three zones, and the smallest working face moving velocity to prevent spontaneous combustion was calculated. Compared with the simulation of the whole process of coal spontaneous combustion in a mined-out area, this proposed method requires a smaller amount of calculations, but its precision can satisfy the demand to predict and prevent spontaneous combustion in the mined-out area.
Abstract: In order to analyze the blasting effect of linear charge at different cavity ratios, the changes of stress field and the destroyed effect at five cavity ratios were investigated by dynamic photoelasticity in experimental models. These were applied to 128 t chamber blasting in Shougang Mine in China. The results indicated that the cavity ratio above 4.0 was suitable. And a bigger cavity ratio in a broken stone area was designed for controlling fly rock.
Abstract: Based on the environmental background of an open pit and the mechanism of dust forming on an automobile soil pavement, the principle of selecting dust suppressive factors such as adhesion, agglomeration and hydrophilicity was established. Sucrose, soluble starch, glycerine, sodium carbonate and sodium silicate were selected and a series of experimental simulations were carried out to test the viscosity, hygroscopic capacity, anti-evaporability at a high constant temperature of 45℃, and anti-jarring performance by milling. In order to analyze dust suppression effect, pure water was used for comparison with the above factors. The results showed that the dust suppressot; which was composed of dissoluble starch, sodium silicate as well as glycerol, possesses a viscosity of 510 mPa·s-1, a saturated suppressor's hydrophilicity percentage of 63.5% and an evaporation rate per unit area of 0.03 g· cm-2·h-1 at 45℃ well as a lasting anti-evaporation time of 65.17 h, provided with high performances of adhesive effect, agglomeration, hydrophilicity, anti-evaporation as well as road surface solidification. Besides, it has strong adsorptive capacity, no secondary dust in insufflation of the dust suppressor; no side effect in mineral preparation and metallurgy as well as is innocuous and harmless to the environment.
Abstract: Aimed to the reinforcement of reinforced soil retaining walls at Wutai cloverleaf junction of Zibo, Shandong province of China and based on the correlative theoretical calculation, a method of enhancing the anchoring force by high-pressure grouting was discussed. The method of grouting with two local layers of steel bar nets was proposed. The result indicated that the lateral displacement was limited effectively with a satisfactory reinforcement effect.
Abstract: It is important to control the effective strengthening depth in the dynamic consolidation of collapse loess roadbed. The consolidation effect was evaluated by analyzing the data of vibration wave from the field test and deducing the formula of strengthening depth. The parallel test of the roadbed strength after consolidation was done by gravity reconnaissance. The better consistency of the derived formula of strengthening depth with the empirical formula proves it is a new and effective method to control the consolidation effect by vibration measurement.
Abstract: Anode plasma electrolysis was used to treat phenol in aqueous solution with high concentration of salt. The generate conditions of anode plasma and the influence of various factors, such as salt concentration, phenol concentration and treating time, on the removal rate of COD were studied. It was demonstrated from the experimental results that, under the conditions of phenol 0.2 g·L-1, NaCl 0.4 mol·L-1, applied voltage 90 V on the bath, the degradation efficiency of phenol was 100% after treatment for 10 min; the COD concentration decreased from 0.464 to 0.01 g·L-1, and the COD removal rate reached to 97.8% after treatment for 20 minutes. Meanwhile, the mechanism of anode plasma electrolysis for treating phenol in high salt aqueous solution was proposed and discussed preliminary.
Abstract: The fundamental or common thermodynamical relations between calcium-treated aluminium-killed molten steel and non-metallic inclusions were discussed. The thermodynamic properties of low carbon Al-killed steel and inclusions in the CSP process were calculated using the interaction coefficients of activity and the Bjorkvall method respectively. A detailed analysis of the CaO·Al2O3 binary system established the modification of solid alumina inclusions via the following intermediate phases:3CaO· Al2O3, CaO· Al2O3, liquid phase 12CaO·7Al2O3 and CaS. The conditions of forming liquid calcium-aluminate inclusions and avoiding the formation of CaS in calciumtreated aluminium-killed molten steel were also discussed using these thermodynamic relations. The results are in good agreement with the plant data.
Abstract: The surface temperature of an SS400 beam blank was measured with an CIT-M Infrared Pyrometer and the hot ductility of SS400 steel was tested in a Gleeble-2000 thermomechanical simulator. The results showed that the surface temperatures of the SS400 beam blank in the secondary cooling area and at the straightening places were normally in 760-880℃, i.e., the fragile temperature range of SS400 steel. The rebounds of surface temperature between some supporting rollers in the second segment of secondary cooling area, caused by discontinuously water spraying, were higher than the permitted range 100℃ ·m-1 according to the metallurgical rules for secondary cooling.
Abstract: The valence electron structure (VES) oft Fe unit-cell bearing alloy atoms was studied according to EET (the Empirical Electron Theory of Solids and Molecules). The result showed that the VES of γ-Fe unit-cell bearing alloy atoms was remarkably different from that of γ-Fe unit-cell. The hybridization states of Fe would go up, and the VES parameters (nA, σN, ∑Nc, σN, etc.) increase in different degrees. An octahedron structure made up of stronger bonds formed in the cell, which could generate a drag-like effect in the course of phase transformation. A further investigation indicates that this octahedron structure can make the austenite more stable and delay martensitic transformation.
Abstract: The precipitation behavior of Ti(C,N) particles in CSP low carbon steel with Ti addition was studied by experimental observation and thermodynamic calculation. Large amount of fine Ti(C,N) particles with 15-30 nm in size were observed, which were precipitated and grew up during the soaking and in the first two hot rolling process. There were only a few TiN particles of more than 50 nm in size precipitated in the slabs before soaking, and no TiN inclusions larger than 1 μm were observed. The results show that the precipitation behavior in the steel produced by the CSP technology is different from that in the conventional one. The effects of small amount of Ti addition on the properties of steels are also different.
Abstract: The phenomenon of magnetic memory that the magnetic leakage field generates on the surface offerromagnetic components in loading state was investigated. The stress of the plate with a hole in the center was calculated by the finite element method and the magnetic leakage field of the plate under the load of tension was measured. The results indicate that stress concentration strongly affects the magnetic properties of ferromagnetic components. Valid magnetic memory signals exist in a small scale of plastic deformation zone. It is feasible to detect the initial damage of ferromagnetic components caused by stress concentration by the magnetic memory testing method.
Abstract: C-Si-Mn TRIP steel was prepared by TSCR process in laboratory simulation. The results of tensile experiment indicated that the mechanical properties were the tensile strength of 610 MPa, the yield strength of 430 MPa, the elongation of 28.4%, and the ratio of yield strength to tensile strength of 0.70. The micmstructure was comprised of ferrite, bainite and retained austenite. The result of quantitative colour metallography showed the retained austenite fraction around 5.8%.
Abstract: The mechanical alloying (MA) technique was used to prepare stainless steel powders containing nitrogen by high energy ball milling under N2 atmosphere and NH3·H2O medium. The effect of MA technique on the property of the powders was investigated. The results showed that the nitrogen content in the powder increased and the powder size decreased with increasing milling time. The nitrogen content in the powder was close to that in high nitrogen stainless steel. The powder size was close to 1.878 μm when milling was carried out for 10 h.
Abstract: A brownmillerite-type of Ca0.5Sr0.5CoxFe1-xO3-δ was prepared using a solid-state reaction method in the temperature range of 1000 to 1200℃. The structure of the material was characterized by means of XRD to seek for a suitable sintering procedure. The conductivities were tested by means of DC four probes. The experimental result shows that Ca0.5Sr0.5Co0.8Fe0.2O1-δ is a material of promising application, which has a single-phase structure and good electrical performance.
Abstract: TiO2 thin film and Fe2O3/TiO2 and Cr2O3/TiO2 thin films were prepared by the photodepositing method on soda lime glass substrates. The results of SEM showed that the surface of Fe2O3/TiO2 thin film was occupied by grain-like oxides while the surface of Cr2O3/TiO2 thin film by net-like particles. The hydrophilicities of TiO2 thin films increased with the doping of Fe3+/Cr3+. The photoeatalytie activities of TiO2 films in photodegradation of methylene orange solution increased with the doping of Fe3+ but varied little with the doping of Cr3+.
Abstract: Polyaniline was electrosynthesized on a carbon fiber electrode in sulfuric acid by the cyclic voltammetric technique. The voltammogram showed four reversible redox systems with the growth process. The electrodeposition charge on the carbon fiber electrode corresponding to the growth of polyaniline increased with increasing aniline and electrolyte concentration, and increased with decreasing scan rate. The open structure morphology of polyaniline was observed by scanning electron microscopy. According to theoretical calculation and the morphology of polyaniline it was proposed that the electrochemically synthesized polyaniline consisted of two types of layers. The first one formed at the early stage of growth and was of a compact structure, while the second layer was of a less dense open structure.
Abstract: In order to develop copper-aluminum composite materials, a new equipment of continuous core filling cast for the bimetal composite materials of copper cladding aluminum was designed and produced, The characteristics of the new equipment were that, the crystallizer was composed of water jacket copper sleeve in which graphite sleeve was set; two melting furnaces with different diameters were vertically distributed, and the low furnace of melting copper was linked the crystallizer; and continuous casting and core filling were proceeded at the meantime. The bimetal composite of copper cladding aluminum was made successfully with the diameter of aluminum of Ф24 mm and the thickness of copper of 8 mm.
Abstract: A numerical simulation on the thermal process for an Si3N4-reaction furnace based on the software CFX was investigated. A similar flow model was used to numerically simulate the laminar flow in the furnace. The influence of some different factors such as volume quantity of N2, anisotropic scattering and radiation properties on the temperature field and mass density of products was studied. The results showed that the temperature control on the preheating zone was important for full reaction. However, the volume quantity of N2, i.e., inlet velocity, plays a crucial role. Anisotropic scattering influenced on the radial temperature and mass density of products. Absorption coefficient and scattering coefficient influenced little on the temperature field. The error between simulated and experimental values was less than 10%.
Abstract: A class of nonlinear singular boundary value problems were studied for the boundary layer of fluid flowing on a conveyor belt. Sufficient conditions for the existence and uniqueness of negative solutions to the problems were established by utilizing the monotonic approaching technique. The numerical solution was presented by using the shooting method.
Abstract: According to the effect of non-deterministic parameters on product performance in the manufacturing and working process, the functional relationship between design variables and steering performance was proposed by the response surface method. The system response disturbed by uncertain factors was simulated. A robust design model of steering mechanism was built up. The optimum value of the system was achieved by using the ideal point approach.
Abstract: To transmit energy continuously to the monitoring system on a rotate part and to make the system stable, an energy transmission technology based on microstrip antennas was put forward. An overall project of the energy transmission system for microstrip antennas was provided for the energy input of transmission antennas, and a separate scheme of power supply was proposed. The energy transmission conditions of a pair of antennas and multi-pairs of antennas were investigated. The crisscross motion conditions ofmicrostrip antennas were analyzed. The results indicated that the energy transmission scheme could meet the demands of practice.
Abstract: A novel multi-resolution wavelet controller used in roll eccentricity control was presented. The control strategy was based on multi-resolution decomposition of roll force signal by use of wavelets. The roll force from a stand represented the cumulative effect of many underlying phenomena such as process dynamics, roll eccentricity, measured noise, effects of external disturbances etc., which manifest on different scales. The wavelet decomposition, which represented the roll force signal at different scales, was compensated for the roll eccentricity signal and removed other uncertainties in control design. Simulated results were shown to validate the control strategy.
Abstract: A new method which uses LVQ neural network in the automatic classification of surface defects for cold rolled strips was presented. The problems of long time and low accuracy in the classification of multi-defect pattern types with some traditional classification algorithms were resolved. Tested by 14 main defect types collected from online data, the results demonstrated that the method of surface defects for cold rolled strips based on LVQ neural network spent little time during training and classifying, and its accuracy could be assured on the recognition process of multi-defect pattern types.
Abstract: The problem about running mode optimization ofa steelmaking workshop system, which is the most complicated subsystem in a steel manufacturing process system was discussed by applying the theory of metallurgical engineering. The level and logical relation of the running mode of a steelmaking workshop in the productive process were described and studied in combination with its applications in Chinese four BOF workshops with the technology of high efficiency continuous casting. Three effects of production mode optimization were summarized and illustrated in detail:(1) the layout of a workshop tending to rationality and briefness, (2) the buffer of working procedures tending to rationality and efficiency, and (3) the operation of working procedures tending to high efficiency and optimization. These conclusions are applied to the research of optimization and control in special steelmaking process operation, and valuable results are acquired.
Abstract: With the research methods of the holism and reductionism of system science, the ironmaking/steelmaking interface characteristics of the six typical processes were analyzed from time, temperature, mass flow quantity, production plan, the effect of hot metal pretreatment, energy consume, environment pollution and so on. A relative superiority of the ironmaking/steelmaking interface of the six different processes was pointed out. The process ofdesiliconization, desulphurization and dephosphorization is only suitable for the process section of the large-scale blast furnace and the large-scale converter, and the process of dephosphorization in BOF is superior. Canceling the mixer and using the same ladle from BF to BOF are the developing direction of the ironmaking/steelmaking interface.
Abstract: After reviewing the core concepts of real options, the features and formation of real options in hi-tech projects were analyzed in combination with the characteristics of hi-tech strategic investment. It was stressed that the coordinative functions between independent projects and the interactive functions between serial projects must be paid attention when figuring out the strategic values of projects. An evaluation mode of hi-tech strategic investment projects was introduced, and the significance was pointed out as well.
Abstract: An image nonlinear filter based on Partial Differential Equations (PDE) has good performance, but it consumes large time and resource. Cellular Neural Networks (CNN) can depict the spatial discrete PDE model, and by means of an CNN analog chip, CNN can solve PDE efficiently. A nonlinear filter based on CNN-PDE was studied, and for selecting the diffusion coefficient properly a noise-estimate technique was presented by means of local operation only. The test result showed that this noise-estimate technique offered a comparatively accurate measure of different noise levels. Simulations of artificial noise images showed that this CNN-PDE nonlinear filter would suppress noise and preserve image edge simultaneously. It is feasible and effective to realize the PDE image process technique by CNN.
Abstract: Based on a generalized chaos synchronization (GCS) system and a generalized Sinai map, a non-symmetric digital cryptographic scheme was proposed. The scheme could hide, in conventional sound signals, various kinds of formatted images which a computer can recognize, realizing information disguise and hiding. This scheme with 24 keys could recover hidden images without any errors. The key space of the scheme was as large as 10360. The scheme had data origin authentication function. Even if a receiver could not communicate with the sender of encrypted data, the receiver can still conftrm whether the data are altered by an intruder. The scheme could be applied in the internet image transmissions disguised via sound signals. The analysis of the key space, the sensitivity of key parameters and the correlation of encrypted signals implied that this scheme had good security.
Abstract: Discretizing continuous attributes in a rough set were researched. Based on the concept of super-cube, all attributes of the information table in data space were globally discretized. By the consistent correlation of condition attributes and decision attributes, important condition attributes were selected depending on their classifying ability in the rough set boundary zone, and furthermore, important breaking points were selected to discretize the information table on a single attribute locally with the iterative constraints of information entropy. Illustration and experimental results indicate that the algorithm combining the global and local discretization is effective and efficient.
Abstract: Many problems arising in mechanics and technology can be formulated as the first kind of singular integral equation. A Wavelet-Galerkin algorithm for solving the first kind of singular integral equation with Hilbert kernel was presented. In the algorithm the characteristic of periodic wavelet on L2([0,1]) and the Hilbert kernel were used to solve and make the stiff matrix lower dimension and become sparser through threshold. The computational amount was decreased and the memory space was saved. Because of the singularity of Hilbert kernel the Tikhonov regularization method was used to solve the stiff equation system. The convergence and the numerical result of approximate solution are discussed.
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
