Abstract: Horizontal and vertical seepage experiments with granular material from Dexing Copper Mine were completed on a multifunctional experimental shelf. The experiment projects were homogenous designed and the data were analyzed in SPSS software. It is shown that the maximum seepage coefficient appears in clown-going flow, the smaller in horizontal flow and the minimum in up-going flow. All the anisotropy coefficients vary from 1.38 to 6.73 and their average value is 4. While the content of coarse grains is in the range of 35% to 60% and the content of mud is 1% to 5%, the seepage coefficient is initially uprising but latter down-going. The seepage coefficient is correlated with porosity in a power function and uprises with enlarging porosity. The porosity declines with increasing content of grains in the range of 0.1 to 0.2 mm and heightens with increasing content of grains in the ranges of 10 to 8 mm and 8 to 4 ram. The relation of seepage coefficient and Reynolds number could he expressed as a power equation and they are identical to determine seepage state. The horizontal and vertical seepage coefficients of Xiyuan dump are 3.68× 10-2 m·s-1 and 1.51 × 10-2 m·s-1, respectively.
Abstract: Based on Johnson distribution curves and the theory of product process quality accuracy control, a method to transform non-normal distribution data was proposed from the view of regionalized variable distribution, and the transformation flow was also designed. With SPSS and Surpac mining software as tools, the applied efficiency of traditional data and Johnson transform methods was analyzed through several cases. It is proved that by using the transformed data of the proposed method, the statistical analysis, fitting and validation of the variation function model, and Kriging estimation could meet the need of stationary, the estimation error can be minimized, and the precision of prediction can be improved.
Abstract: The effects of crystalline structure, anatase, rutile and mixing crystal, on the visible-light photocatalytic performance of TiO2 were studied with reactive red X-3B and phenol as model pollutants. The results showed that the degradation ratio of reactive red X-3B after 80 min reaction could be as high as 100% when using anatase or mixing crystal TiO2 as photocatalyst under the condition of Vis/O2, but the degradation ratio was less than 15% when using rutile TiO2 as photocatalyst. Phenol could be degraded under the condition of Vis/TiO2 by any of the three photocatalysts; rutile form exhibited a better photocatalytic activity, and its degradation ratio could be 54% after 180 min reaction. Fluorescence spectrum analysis indicates that the reaction process is predominated by the generation of ·OH radicals in the system. In the process of TiO2 visible-light photocatalysis, hydrogen peroxide is generated by anatase TiO2 from a series of complex reactions, and the generated hydrogen peroxide is absorbed on the surface of TiO2 to form active species, which is responsible for the generation of ·OH radicals and the degradation of organic pollutants under visible light irradiation.
Abstract: Transient phenomena often happen in water distribution systems (WDS). In order to accelerate system transformation from unsteady state to steady state, two mathematical models were proposed based on the theory of transient flow, which are the method of characteristics (MOC) with re-divide damping coefficient and the lattice Boltzmann equation (LBE). These methods were used to calculate an example in WDS. It is shown that LBE is more accurate when Reynolds number is less than 7 000, otherwise MOC is more precise.
Abstract: The influence mechanism of MgO on sintering liquid forming and solid phase reaction and the effect of MgO flux on the strength of solid phase were investigated, and sinter pot experiments were carried out. The results show that with the content of MgO in sinter increasing, the initial forming temperature of sinter liquid phase rises, but the fluidity of liquid phase and the strength of bonding phase decrease. When different MgO fluxes are used, the strength of bonding phase in sinter appears diverse. Furthermore, at 1280~C and 1 320~C, the strength of bonding phase when sintered with serpentine is much higher than that with light-burned dolomite and dolomite is the worst. Based on the yield, quality and metallurgical properties of sinter, the desirable mass fraction of MgO is about 1.2% and for MgO flux either the composite of dolomite and serpentine or the light-burned dolomite alone is better.
Abstract: To investigate the effect of residual elements Cu, As and Sn on the hot ductility of steels, the hot ductility of low alloy steel continuous casting slabs containing some Cu, As and Sn was measured by tensile tests with a Gleeble-1500 tensile test machine. It is found that the low ductility region Ⅲ is between 920 and 730℃. Embrittlement in the region Ⅲ is caused by Cu, As and Sn segregation along the austenite intergranular in the austenite single-phase low-temperature range, which weakens the binding energy of the intergranular and induces brittle fracture along the intergranular; the precipitation of proeutectoid ferrite film along the austenite intergranular in the austenite and ferrite two-phases range induces intergranular cracks. Cu, As and Sn in the steel increase the width and depth of the low ductility region In and enhance its upper limit critical temperature.
Abstract: The behavior of precipitation in hot bands of grain-oriented electrical steel produced by the inherent inhibitor method was investigated by means of transmission electron microscopy (TEM). The effects of slab reheating temperature on secondary recrystallization and magnetic properties after secondary recrystallization annealing were discussed. Experimental results show that most of the particles in hot bands are complex copper-manganese sulphides. As the slab reheating temperature increases, an increase of Cu/Mn ratio in the sulphide particles is associated with a simultaneous decrease in size, the dispersive particles become more homogeneous and more/kiN precipitates. Consequently, the inhibiting effect on primary grain growth is enhanced, the secondary recrystallization is more complete and the magnetic properties are improved.
Abstract: The microstructure of China low activation martensitic steel (CLAM) was investigated after irradiation by hydrogen ions. After irradiation, precipitates were found in basic CLAM steel and in CLAM steel added silicon. Chromium is one of the alloy elements which increase precipitates after irradiation, but silicon is one of the alloy elements which suppress the damage of irradiation.
Abstract: The concept of metal gradient structure shafts was put forward firstly. The microstructure, diffusion behavior of Cr element, and variation in interracial microhardness of a 25CrSMoA/Q235 clad shaft prepared by solid-liquid cladding were investigated by scanning electron microscope and microhardness tester. The bonding interface of the 25CrSMoA/Q235 cladding shaft forms close metallurgical bonding after extrusion deformation, and it is difficult to be identified except the difference of individual structure. Cr element in a region adjacent to the bonding interface is fully diffusive and appears continuous distribution during solid-liquid bonding. Across a region ranging from the bonding interface to both sides by the distance of 100μm respectively, the microhardness distributes continuously and uniformly. Additionally, during heat treatment, increasing the heating temperature and holding time makes Cr distribution in a region adjacent to the bonding interface more uniform and the slope rate of Cr distribution curves at the bonding interface reduced more, which greatly reduce the microhardness at the 25CrSMoA side adjacent to the bonding interface. It is advantageous to form gradient variations in chemical composition, structure and mechanical properties at a region across the bonding interface.
Abstract: Hydrogenation experiments that involved gas-solid hydrogenated method with a tube-hydrogen treatment furnace were conducted to investigate the change in hydrogen content of porous Ti-6A1-4V alloy with temperature, time and its relative density, and some corresponding mathematical models were proposed on the base of experimental data. It is shown that, for the porous titanium alloy with low relative density, the hydrogen content increases at a higher hydrogenation temperature; as for the porous titanium with high relative density, the relationship between hydrogen content and temperature obeys the Sievert's law, which is consistent with that of a compact titanium alloy. The hydrogen absorption capacity increases as the hydrogenation holding time prolongs, while it decreases as the relative density of the porous titanium alloy increases.
Abstract: Coatings were obtained by micro-arc oxidation on the surface of a Ti6A14V alloy in the electrolyte contained different contents of Na2SiO3. The surface micromorphology and roughness of coatings were analyzed by SEM and AFM, and the effects of Na2SiO3 content on the thickness and surface micromorphology of coatings were investigated. The results show that the thickness of coatings increases from 31 μm to 88 μm and the critical arcing forward voltage decreases gradually when the mass concentration of Na2SiO3 in the electrolyte increases from 12g·L-1 to 28g· L-1. There are many microholes with different sizes on the surface of coatings, and the amount of microholes and the roughness of coatings increase as the content of NaaSiO3 in the electrolyte increasing. It is found by X-ray diffraction analysis that the coatings are composed of anatase and ruffle.
Abstract: Microstructures of in-situ reactive near-liquidus cast Al2O3/Al-Cu matrix composites were observed by optical microscope, and transmission electron microscope was used to examine the distribution and morphology of in-situ Al2O3 particles in the Al-Cu alloy matrix. The effect of in-situ Al2O3 particles on the formation mechanism of mierostructure of the near-liquidus east Al-Cu alloy was analyzed. It is shown that as-cast microstructures of the in-situ processed composites have a relatively uniform distribution of Al2O3 particles within 1 μm in average size and the Al2O3 particles have polygon morphology. The rose-flowered structure gradually fines and homogenizes with increasing the mass fraction of in-situ Al2O3 particles; while the mass fraction of Al2O3 particles is up to 5.3%, a fined and homogenized rose-flowered structure is obtained.
Abstract: The effects of some factors such as filling methods, filling time and filling times on the filling of precursor in a colloidal crystal template method were systemically investigated for preparing SiO2 ordered macroporous materials. The results show that a direct dipping method usually brings shrink, desquamation and surface overlay. A new filling method was presented, which is dipping the template after covering glass on it, and the method can effectively solve the above problem. Experimental data reveal that when the filling time is 5 rain and the prepared macroporous materials are filled two times, the filling ratio is higher. Scanning electron microscopy (SEM) images and spectrophotometer results indicated that SiO2 ordered macroporous materials with large area were successfully prepared and the filling ratio reached 22.53%.
Abstract: Water modeling and numerical simulation were applied to investigate the influence of the port angle of a submerged entry nozzle (SEN) on the flow pattern in a slab continuous casting mold. The results indicate that under the current 15° SEN, the surface velocity and fluctuation are relatively small at meniscus, which does harm to the melt of mold powder. The impinging point of jet flow streaming from the SEN is relatively low. Below the point, the pressure on the solidifying shell is relatively high. The sharply decreasing frequency of breakout alarms and no breakout were achieved after a new 10° SEN was put into operation.
Abstract: In order to meet the requirement of schedule-free rolling for wide non-oriented electrical steel strip production with a large number of the same width strip rolling campaigns, an asymmetry self-compensating work roils (ASR-C) technology was developed. A three-dimensional finite element analysis model of roll stacks was built by ANSYS software package. The finite element analysis and industrial tests indicate that the developed ASR-C technology has both crown control ability and wear control ability for different widths of strips or different rolling periods within the entire roiling campaign. At the same time, the roll gap stiffness and the crown control range by bending force with asymmetry self-compensating work rolls are greater than those with conventional work rolls in hot finishing mills. The ASR-C technology has been applied to production of the same strip-width 2.55 mm× 1280 mm wide non-oriented electrical steel strips in the 1700 mm hot strip mill of WlSCO for test. The industrial test results show that the rate of the measured strip crown less than 45μm is increased from 41.8% to 98.2%, the rate of the measured strip crown more than 53μm is decreased from 33.9% to 1.8%, and the self-maintenances of roll contours for ASR-C reach to 88%. The schedule-free rolling (SFR) for a large number of the same width strip rolling campaigns is significantly achieved by the ASR-C technology with stable crown control ability and wear control ability.
Abstract: A strip profile along its width is correlative with strip flatness control. Conventional strip profile definitions cannot describe the abnormity of cross sections accurately, and affect strip profile quality and control precision. Multi-factor strip profile definitions were presented, which described strip profiles more comprehensive. Taking CVC mill as an example, based on the ANSYS finite element model, a coupling relation of strip profile factors was analyzed. It was proposed that the general control of strip profile factors and coupled control with flatness were difficulty and also the key to high-quality steel rolling.
Abstract: Based on shape and gauge decoupling design, coupling relations between crown control and flatness control were analyzed to establish crown and flatness coupling models for different shape control schemes, and the coupling characteristics were analyzed and compared. Crown and flatness semi-decoupling design was put forward according to the coupling models' characteristic. A crown and flatness decoupling control system and its application strategy for tandem cold mills were designed to accomplish a dynamic shape control system. After operating in a 1 420 mm 5-stand UCMW tandem cold mill, the dynamic shape control system approves good ability of improving shade and gauge control nreeision.
Abstract: Roll eccentricity in rolling mills has an important influence on the delivery gauge of rolled strips. An online back propagation algorithm with memory range was used to identify roll eccentricity and compared with the simple online back propagation algorithm on identification. The results show that the roll eccentricity identification method with memory range has a faster convergence and a better anti-noise performance. It can make the thickness fluctuation decrease about 95 96 when the eccentricity's magnitude, phase and frequency change, consequently compensate thickness error induced by roll eccentricity and improve the delivery gauge of rolled strips effectively.
Abstract: An ant colony algorithm of self-organization resource allocation for dynamic procedure networks in production process was proposed to improve the validity of resource allocation in steel-making and continuous casting production planning. A production planning model for steel-making and continuous casting was established with sequence casting constraint. In the model, the objective is to minimize the operation conflict time and the queue waiting time and to start pouring early. The ant colony algorithm was designed on the base of the time and space reverse relation of structure of procedure networks in production process. The test with production data in a commercial steel plant shows that the model and algorithm can draw quickly a high-quality and performable production plan.
Abstract: A decoupling control approach based on inverse systems was developed for permanent magnet synchronous motors (PMSM). A novel inverse control scheme was proposed to decouple the performance of PMSM. On the base of the reversibility analysis of the PMSM's mathematical model, the PMSM system is decoupled into a second-order linear speed subsystem and a first-order linear stator current subsystem. Simulation results show that the proposed control scheme possesses excellent control performance and good robustness against load disturbance.
Abstract: The idea of free-weighting matrices was extended to a class of stochastic systems with time-varying delays, and the delay-dependent stability of the stochastic systems was studied. By establishing a new Lyapunov function and introducing appropriate free-weighting matrices, a sufficient delay-dependent condition was proposed for the asymptotic stability of such a system. The result was in the form of linear matrix inequalities completely and model transformation was unnecessary. Two examples were given to illustrate the effectiveness of the proposed method.
Abstract: A preview control problem of a generalized discrete-time linear system was studied. First an extending error system was constructed by applying the difference method to the system equation, the error vector and the objective value signal. This converts the problem from a preview control problem of an extending system to a common control problem in analysis. Then, using the result of the optimal control theory of the generalized system, a controller with preview action of the generalized system was got. Also, a matrix Riccati equation was converted by decreasing its rank, which enables the closed-circular system.
Abstract: A fragile audio watermarking method for MPEG-2 AAC bitstreams was proposed. The algorithm of watermark embedding was carried out by modifying the LSBs (least significant bits) of quantized MDCT coefficient's magnitude that is greater than 15, and was improved by considering the watermark's distribution in frequency and the perceptual entropy of host audio. Experimental result shows the proposed watermarking scheme is not appreciable, and it is possible to insert high hide rate additive data effectively into encoded bitstreams. The embedding and retrieving process is easy and it is adaptive for real-time analysis applications.
Abstract: A commercial production line of compact strip processing and a production technology for conventional grain oriented electrical steel were used to manufacture low cost grain oriented electrical steel, whose magnetic properties reached the level of 30Q150. Proper hot band annealing was introduced in order to obtain coarse grain size which promoted the strengthening of Goss texture as well as the increasing of inhibitors' number, so that the magnetic properties could reach the level of 30Q140.
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
