Abstract: Based on the magnetotelluric (MT) theory, a technical law of high precision electromagnetic spectrum was illustrated. From comparative analysis of experiment, the exploring depth and the electromagnetic frequency could be regarded as a linear relation in local area, which made the stratum resistivity correspond to the exploring sounding curve. An observation system of underground coal seam resistivity using multi-channel exploring method was designed. As a sensor, the paralleled capacitor overcame the disadvantage of volume effectiveness and improved the exploring precision. The system is adopted to explore coal seam and oil-gas. In comparison with the practical drilling data, the accordance gives out a satisfied result with a figure of 80% or more.
Abstract: According to the theory and method of particle flow code in two dimensions (PFC2D), the block caving law of natural caving mining method was investigated. Based on the geologic conditions and the physical and mechanical properties of rock in a nickel-copper mine, the caving law in natural caving mining method was simulated by numerical method. The results show that the mechanical mechanism of natural caving method can be analyzed by PFC2D modeling, and the mining process of natural caving method is simulated effectively. The parameter variation of rockbody during the process of mining can be demonstrated easily. The initial caving radius of undercut in the mine is 10 m, and the continuous caving radius of undercut is 22 m. The numerical modeling is effective to guide the mining process of natural caving mining method in the mine.
Abstract: Batch experiments of magnesium ammonium phosphate (MAP) precipitation were conducted to examine the optimal conditions for recovering MAP from simulated NH4+-N wastewater. The experimental results indicated that the precipitates consisted mainly of MAP when the pH was maintained between 8.0 and 11.0. The precipitates, produced at pH 10 and the molar ratio of n (NH4+):n (Mg2+):n (PO43-) was 1:1.4:1, were pure MAP, 3.14 g MAP was attained from 1 L simulated wastewater and the removal rate of NH4+-N could reach 91.5%. It is shown that the application of chemical precipitation method can be promoted for the cost of it could be considerably decreased by recovering MAP.
Abstract: According to the characteristic of antibiotic wastewater, industrial experiment was carried out by hydrolytic acidification membrane bioreactor (MER) process. The MBR's running parameters and treatment effect were systematically investigated during the treatment. The results show that when the volume loading of the MBR is 7-10 kg·m-3·d-1, the removal rates of COD, NH4-N and TN are up to 90%, 80% and 65%, respectively. The water quality of the effluent can meet the secondary discharge standard of the GB18918-2002 Integrated Wastewater Discharge Standard of China.
Abstract: To improve the biological treatment effect of paper-making wastewater, the screening and identification of strain degrading lignin and its application were carried out. The strain able to degrading lignin was obtained after a series of experiments including sampling, domesticating, separating and identifying etc, and it was defined as a white-rot fungi, short-rod, aerobic alkali-producing bacteria based on investigations on its physiological and biochemical prosperities. After Gram's stain, the strain was identified as a Gram-positive bacterium. In further research, the strain strongly capable of degrading was selected to apply in wastewater treatment experiment and the results showed that this bacterium possessed a removal rate of 80.9% for CODCr in waste-water from paper mills, which displayed good prospects of application.
Abstract: The compositions of low melting point inclusions in a CaO-SiO2-Al2O3-MnO system were calculated and analyzed by thermodynamic software FactSage. The results show that the area of low melting point inclusions first increases then decreases with the alumina and calcium oxide contents accumulating. However, it always increases with the silica and manganese oxide contents rising. To obtain low melting point inclusions, the alumina and silica contents should be approximately controlled to 20% and 30%, respectively, the CaO content restricted to 25%-30%, and CaO/SiO2 should be 0.8-1.
Abstract: An ingot specimen was obtained by the process of adding Al2O3 nano-particle to molten industrial pure iron. The existent state and chemical components of nonmetallic inclusions in the metal-phase sample were investigated by SEM and EDS. Nonmetallic inclusions were extracted from the ingot by the electrolytic method in nonaqueous solution, and SEM and EDS were used to study their characteristics, such as morphology, size, and chemical components. The results showed that additive Al2O3 nano-partlcle could be stabilized and combine with microelements, such as Mn and S to form complex inclusions, whose size is about 5-10 μm. Al2O3 nanoparticle existed usually in the interior of complex inclusions. The phenomena of reuniting and agglomeration of Al2O3 nano-particle was rare. The thermodynamic stability and probability of reuniting and agglomerating of Al2O3 nano-particle were also analyzed in molten pure iron.
Abstract: Using layer-by-layer shave steel scrap, the effect of electromagnetic stirring frequency parameter at secondary cooling area on the central segregation and equiaxed crystal ratio of a 1 450 mmx 230 mm slab was investigated by chemical analysis and macrostructure. On the basis of data analysis, three conclusions are drawn:(1) the central segregation is obviously improved when electromagnetic stirring is applied at secondary cooling area, and the positive segregation coefficients of C, P and Mn are lower than those of no electromagnetic stirring; (2) the level of central segregation is all 130.5 when the electromagnetic stirring frequencies are 2, 5 and 8 Hz; and (3) electromagnetic stirring frequency has slight influence on the central equiaxed crystal ratio, and the largest equiaxed crystal ratio appeased in the case of 5 Hz frequency.
Abstract: The microstructure evolutions during deformation-enhanced transformation of undercooled austenite of Nb-microalloyed steel and low carbon steel with the similar contents of C and Mn were investigated by hot compression simulation experiment. The effect of Nb on the deformation-enhanced ferrite transformation was studied, and the transformation kinetics was analyzed. The results show that Nb(CN) precipitation promotes ferrite nucleation significantly before deformation-enhanced ferrite transformation. Ultra-fine ferrite with a grain size of about 1.9 μm is formed in Nb-microalloyed steel during deformation of undercooled austenite between A3-Ar3. Deformation-enhanced transformation is the dominated process in the early stage of deformation; as ferrite transformation accomplished, the ferrite grain size of Nb-microalloyed steel is smaller than that of low carbon steel.
Abstract: The microstructure, magnetic property and anisotropic mechanism of NdFeB as-cast powder and the material in different HDDR treatment stages were investigated. It is found that the anisotropy of NdFeB as-cast powder is greater than that of HDDR NdFeB materiacs. The anisotropy of HDDR NdFeB material decreases monotonously and finally disappears with the disproportionation time prolonging, which means that the anisotropy of HDDR NdFeB material originates from as-cast texture. Short disproportionation time is helpful for the anisotropy attainment. As an anisotropy passing medium, the disproportionation lamella microstructure transfers the anisotropy of as-cast powder to the final HDDR NdFeB material by means of crystallographic orientation.
Abstract: A new technique was proposed for rapid and accurate texture measurement of AA3104 hot bands. Based on the sample and crystal symmetry of aluminum bands, the diffraction data along an arc in pole figures were measured using the transmission technique, which avoided the heterogeneity of the reflection technique. A fitting treatment based on Gaussian distribution was introduced, and the characteristic parameters of each texture were obtained. The reproduced pole figures based on the characteristic parameters are in good agreement with those obtained by the conventional way, which predicts the main texture components satisfactorily. In principle, an industrial technology for on-line texture determination could be developed based on this technique.
Abstract: TiC/Fe composite coatings were successfully obtained by reactive flame spraying (RFS) with ilmenite, graphite and ferrous powder as rough materials. The microstructure of the composite coatings and the relations among their wear properties, phases and microstructure were investigated by X-ray diffraction, scanning electron microscopy and transaction electron microscopy. The results show that the composite coatings mainly consist of TiC and Fe phases and were composed of alternate soft and hard layers with different TiC contents. In the TiC-rich layers, lots of submicron (< 0.5 μm) and approximately round TiC particles are dis-persed in the iron matrix. This multiphase and multilayer coatings will be helpful to improve the wear resistance of cermet composite coatings.
Abstract: Utilizing the manual simulation method in laboratory a self-assemble multilayer was made through anion-cation polyelectrolyte weak solution. The glass substrate equipped with the self-assemble film was put into the simulated body fluid SBF, and under proper conditions the aggradation of hydroxyl apatite was induced on the film. It is shown that the pH value of the SBF solution has much influence on crystallization of hydroxyl apatite. The most compact crystal was observed at pH 7.40 with the self-assembled film and simulated body fluid. The inducing experiments of bio-mineralization indicate that the self-assemble film made from the polyelectrolyte weak solution can be successfully used in the study of bio-mineralization materials.
Abstract: According to the theory of heat transfer, BF hearth bottom models were built based on actual examples by software with VC language, the calculated results in good accordance with the data of BF thermal couples. Temperature distribution and the capability of resistance to erosion were analyzed for the two prevalent kinds of hearth bottom, called "heat transfer method" hearth with small carbon bricks of high thermal conductivity and "heat isolation method" ceramic synthetic hearth bottom. Different ways in protecting hearth bottom were clarified by analyzing some actual examples. The result shows that the existence of a "protecting skull" with low thermal conductivity between hot metal and brick layers is the same essence of prolonging the life of hearth bottom, and the disadvantages of the two kinds of hearth bottom were analyzed.
Abstract: Continuous tracking measurements were conducted for eliminating the chatter marks of a 1700 temper mill. The character of vibration and the interaction between vibration and chatter marks were found based on the study of inherent characteristics of the temper mill and the analysis of vibration signals in different periods. The primary vibration model was self-sustained vibration and the vibration frequency was 150 Hz in initial stage, but in steady stage the relative movement between the work roll and the backup roll induced chatter marks. In middle and final period the primary vibration model was a coexistence of forced vibration and self-sustained vibration, and the forming process of chatter marks was accelerated by forced vibration resulted from chatter marks. Based on the above studies some countermeasures are derived as follows:adding a roll to control vibration in the inlet side or changing the speed of temper rolling.
Abstract: A novel unsteady-state membrane permeation process was proposed based on steady-state permeation. The process is composed of three basic cyclic steps:feed pressurized, permeate withdrawn, and residue vented. The effects of pressurization time, evacuation time and venting time on the average purity, productivity and recovery of nitrogen were experimentally investigated for air separation to produce nitrogen by this process. The effectiveness of the process was compared with that of steady-state permeation. The results show that the average purity, productivity and recovery of nitrogen increase with the prolonging of pressurization time under the experimental conditions. The average purity of nitrogen-enriched gas is increased but its productivity and recovery are decreased when the evacuation time is extended. An appropriate increase in venting time is associated with the increases of average purity, productivity and recovery of nitrogen. When the venting time is too long, the productivity and recovery will be decreased. As a result, the proposed process in this paper can achieve a higher purity of nitrogen but a lower productivity and recovery.
Abstract: The Laigang 1 500 mm hot strip mill is a set of fully automatic hot strip mill designed and manufactured by us. The automatic jump control (AJC) of wrapping rolls is very important for the final quality of products. The system is the first set of AJC system based on Siemens TDC and designed by us. The system functions were programmed in Siemens STEP7 and friendly HMI was designed with Siemens WinCC. The system, with comprehensive functions and high precision, was applied on the Laigang 1 500 mm hot strip mill and satisfactory results were obtained.
Abstract: A quality monitoring method for strip hot-dip galvanizing based on partial least square regression was proposed. Taking the quality monitoring of mechanical properties and zinc coating mass in strip hot-dip galvanizing as the investigated subject, a regression model between process parameters and quality results was constructed through partial least square method. With the regression model, the capability of production process control was analyzed and a production quality prediction method was presented, Real field data from strip hot-dip galvanizing production in Angang Steel Company Limited were used for validation, The results show that partial least square regression has a better predicting precision than traditional multiple linear regression, and that the zinc coating mass prediction model based on partial least square regression has a relative prediction error of 5.93%.
Abstract: In view of the changing of a clod-rolling gaugemeter-type automatic gauge control (AGC) model and the gauge feedback resulted from long time-delay under low-speed rolling, a modified method of gaugemetertype AGC for cold-rolling to attenuate the bad influence resulted from uncertainties of the system was proposed. A new gain adaptive algorithm was deduced for an over two-order system with time-delay, and a principle for selecting controller parameters was given to ensure robust stability of the system. Simulation result shows that this method can effectively attenuate disturbance of the system, and stabilize the system when the parameters of the system is changing.
Abstract: A kind of 3-dimensional three-linear hybrid chaotic system was achieved by adding feedback control item under discontinuous state, which is a switching type of piecewise-linear controller to a 3-dimensional unstable linear system. Systemic dynamic analysis was accomplished for a kind of three-linear hybrid chaotic system, and three theorems were given. Numeric simulation and calculating all Lyapunov exponents verify their chaos.
Abstract: In reality, an object is often described as a complex system with multilayer structure, of which any sub-layer has many properties. According to the principle of extenics, in order to establish the extension model of affair element for a complex system, the concept of multilayer multidimensional affair element extension set and its positive field, negative field and extension boundary were presented based on the concept of n-dimensional affair element extension set. The definitions of positive extension field, negative extension field, positive stable field and negative stable field of a multilayer multidimensional affair element extension set were given. The properties and intersection operation of the set were discussed and proved strictly. The expressions of extension field and stable field for intersection operation of the set were gained.
Abstract: Based on over 180 HBeAg negative patients' anti-HBV infection therapy data of adefovir dipivoxil with placebo for an international co-operation research and the HBV infection dynamic model proposed by Nowak et al, a mathematical model consisting of two differential equation systems was built. This model provided a possible interpretation of the curative effect of adefovir dipivoxil with placebo for HbeAg negative chronic HBV infection patients, particularly explaining why the plasma virus of the patients turnover after stopping the adefovir dipivoxil therapy. This model predicts the long time adefovir dipivoxil curative effect that the patients whose plasma HBV DNAs is near the median values need to prolong treatment time until 5.6 years to delete HBV virus in bodies. This research implies also that the popular treatment standard of HBV DNA<500 copies·mL-1 is too rough to evaluate the effectiveness for aniti-HBV infection therapy.
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
