Abstract: The thermal analysis was used to study the oxidation and thermal degradation reaction of coal with different oxidation degrees of coal. The results showed that in the air this reaction of coal could be divided into five stages, e.g. moisture content vaporizing, weighing by absorbing oxygen, thermal degradation by heating, firing, and firing last. The two stages of coal's oxidation, weighing by absorbing oxygen and degradation by heating, were studied. The oxidation reaction of weighing by absorbing oxygen is a first-order chemical reaction, and the thermal degradation reaction by heating is a 3/2-order chemical reaction. The average activation energy E and lnA at different stages of oxidation were calculated. The feature of oxidation process and the rule of E and lnA at different oxidation processes were analyzed. A reliability of calculated kinetic parameters of the oxidation reaction was checked by the drawing method.
Abstract: In order to study the effect of ground water on high and steep open pit slopes, FLAC^3D was employed to simulate and analyze the stability of a high and steep open pit slope. The comparison was made on the effect of the stress, failure zone and displacement in the slope under the condition of ground water or not. The result indicated that ground water reduces the stability of the high and steep open pit slope. A new method for stability assessment of the slope was proposed so as to give rise to reliability of the numerical simulation, which estimated the stability of the slope through the comprehensive analysis of the movement trend of velocity at the tracing points in the model, the failure zone as well as the displacement.
Abstract: The analysis was done about site earthquake damages in the Pearl River Delta area, such as active rift, sand liquefaction, soft soil earthquake sinking, karst collapse earthquake, landslide, dilapidation and island terrain. The result showed that sand liquefaction and soft soil earthquake sinking would be the main site earthquake damages in this area in the future, and the effect of other site earthquake damages could not be neglected in the meantime. It would be a new tendency that how sand and soft clay largely absorb seismic energy in order to prevent building collapse in a strong shock.
Abstract: Fly ash samples from a hazardous waste incinerator burning 70 % industrial wastes and 30 % medical wastes were analyzed for heavy metals. The leaching toxicity, chemical form and concentration distribution of heavy metals were examined. The results suggested that Cd, Pb and Zn were the main heavy metals and the contents of those metals were as several times as those in fly ash from an MSW (municipal solid waste) incinerator. Heavy metals existed as exchangeable, bound to carbonates, metal oxides, organic matters and residual forms. In all heavy metals, Cd, Pb and Zn showed the higher leachability while As, Cr and Cu were more chemically steady. Cd and Cu mainly concentrated on small particles. Pb and Zn were enriched on 50-125μm and 125-250μm particles.
Abstract: In the winter, the operating efficiency of ecological beds is not satisfied. Four psychrophilic bacteria were cultivated and separated, and their physiological characteristics were tested. The experimental result shows that the growth rate of the mixed psychrophilic bacteria can reach to 0. 058 h-1, but that of the mesophilie bacteria is zero. The operating efficiency was greatly improved after adding some psychrophilic bacteria, and the removal ratio of Zn is 25 times than that adding no psyehrophilic bacteria.
Abstract: The theoretical background of calculating sulphide capacity by the KTH model and the method of calculating sulphur partition ratio were introduced. Some parameters that affect the sulphur partition ratio were studied. The result showed that (1) the sulphur partition ratio increased with the increase of [%C], [%Al] and decreased with the increase in temperature; and (2) the sulphide capacity increased with the increase in temperature and decreased with the increase of [% Al2O3]/[% CaO] in the slag.
Abstract: In order to understand the mechanism of short-circuited deoxidization, an experiment was designed and performed for measuring the relation between the open circuit voltage of a deoxidization device and the process time. A theoretical formula was applied to this process so that the open circuit voltage could predict the limit of deoxidization reaction. The experiment results show that this experiment and theoretical analysis are successful.
Abstract: Argon gas injection into a slab continuous casting mold through the submerged nozzle changes the mold flow region. Surface level fluctuation in the mold would lead to slag entrapment in billets. The influence of argon injection on slag inclusion quantities and types in billets was investigated by means of SEM and bulk sample electrolysis. The reasonable technological parameters, such as the quantity and distribution of argon injection, were analyzed and provided for avoiding slag entrapment in billets. The result showed that the mass ratio of slag entrapment to the inclusions in the mold was beyond 50 % and the optimized argon gas injection was significant to reduce slag entrapment.
Abstract: Marine polymetaUic nodules were mainly consisted of manganese and iron oxides. The experiments prove that it was feasible to extract manganese from nodules and enrich copper nickel cobalt oxides in the residues by the method of tri-phase oxidizing. The optimized parameters are: 240℃; 2 h; a ratio of the amount of substance of KOH/MnO2 about 45; an air supply of 0．5m3·h-1; a particle size of powders less than 200 mesh. The enriching ratio of Fe and Ni is nearer 100 % and those of Cu and Co are both more than 93 %. The metals which located in the matrix might accelerate the decomposing of potassium manganete; for the potassium manganete was soluble, this reaction also realized the seperation of manganese and other metals.
Abstract: A mathematical model for dendritic growth of steady-state in the temperature field is established, and the analytical solution is derived in the form of Fourier series from separation of variables in the complex number field. The heat transfer characteristics in some special cases are discussed. Through the figures a clear view can be acquired about the substance of crystal growth.
Abstract: The surface oxidation of strips was investigated in order to study the influence of hot-rolling lubrication on the surface quality. The results showed that the surface quality was greatly improved by hot-rolling lubrication. The thickness of the oxidation layer under oil-water lubricating condition was just 5 μm, which was 3 μm thinner than that under water lubricating condition and 7 μm thinner than that without lubrication. Surface topographies were observed and rolling grains were vividly seen on the surface of strips.
Abstract: Using carbon, iron, silicon, ferrochromium, ferrotitanium and nickel powder as the raw materials, chromium carbide/Fe-based composite coatings with an even and smooth surface were prepared by vacuum reactive braze coating, which combined with a mild steel substrate by a metallurgical bonding. The phase structure, composition distribution and hardness distribution of the coatings were studied by means of scanning electron microscopy (SEM), energy dispersive spectrum (EDS), X-ray diffraction (XRD) and microhardness testing. The results showed that the coating had a composite structure, and the microstructure of the coating consists of an Fe-Ni solid solution matrix and in-situ synthesized hexagon prismy Cr3C2. There was a transition zone between the coating and the substrate, in which chemical elements and microhardness had a gradient distribution. The surface hardness of the composite coating was high up to 85HR15N.
Abstract: The galvanic behaviour of a Q235-304L couple was studied by the electrochemical method and immersion test. Surface morphologies of the samples were observed by SEM after rust cleaning. The results showed that both the cathodic and anodic processes of 304L were controlled by the electrochemical activation step in all the three solutions with pH values of 4.0, 7.0 and 13.3, and both the cathodic and anodic processes of Q235 in the solutions with pH values of 4.0 and 7.0 were controlled by the electrochemical step, while the anodic process of Q235 exhibited an apparent characteristics of diffusion control when the pH value of the solution was 13.3. As the area ratio increases, the galvanic effect increased in all the three solutions accordingly, but the correlation between the galvanic current and the cathode/anode area ratio did not accord to the rule of logarithm. With the elevation of pH value, the galvanic corrosion rate of Q235 would greatly decrease, but the change of the galvanic effect was not so obvious.
Abstract: The Suzhou kaolin sample and the fired kaolin samples at different calcination temperatures were characterized with XRF, SEM, XRD, IR and NMR. The results showed that the fired kaolin samples were transformed from crystal to non-crystal, and calcination temperature had some affects on their morphology and structure: the higher the calcination temperature, the fewer the small particles with rod and plate morphologies, and the fewer the AIIV in the fired kaolin.
Abstract: Three kinds of porous composites based on poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and bioactive glass (BG), tricalcium phosphate (TCP), hydroxyapatite (HA) respectively were prepared for born tissue engineering scaffolds. The chemical reactions and in vitro degradation of PHBV/ BG, PHBV/TCP and PHBV/HA porous materials under physiological condition were assessed and compared. The changes in surface micromorphology, composition and structure of the composite scaffolds were investigated before and after immersed in simulated body fluid (SBF) solution. It was found that biodegradation occurred for three kinds of scaffolds which led to the weight loss of the scaffolds after immersed in SBF solution. The biomineralized reaction and ion exchange reaction occurred in PHBV/BG and PHBV/ TCP scaffolds in SBF solution, and the mineralized layer formed on the surface of those scaffolds which was analyzed as hydroxyl carbonate apatite (HCA). There was little biomineralized reaction appeared on PHBV/HA scaffolds during immersed in SBF sulotion.
Abstract: Two kinds of geophones and their installing techniques used in microseismic monitoring underground coal mines were introduced. The method of installation with hydraulic expander can be used in middle hard and hard strata while the depth of drilling holes should be less than 50 m and geophones can be recycled. The method of installation with cement pouch can be used in soft strata and the depth of drilling holes can reach 50-100 m. These geophones and their installing techniques were investigated by field tests and have successfully applied in underground coal mines.
Abstract: The dynamic mathematic model of a looper height and tension system was built on field data for hot strip finishing mills. A control strategy based on BP-PID was introduced to decouple the looper system by using FPGA, which includeds systolic mapping, data representation and precision, and computation components design. Simulated results showed the effectiveness of the algorithm and the applicability of the control strategy.
Abstract: To avoid the interference of model between acceleration and wavelength electromagnetism to magnetoelectric sensors, a mathematical was proposed with the analysis of fiber Bragg grating acceleration sensors' mechanical model, and then a low frequency fiber Bragg grating acceleration sensor was designed. With the experiment, the frequency range of amplitude is 45 Hz and the cross-axis disturbance is 40 dB, which means that the sensor can be used in practice.
Abstract: A strategy and principle of the optimization of pass schedule named equal reduction were first proposed in order to reduce the time of Flying Gauge Control (FGC) and improve the stability of FGC process. An actual example was given, and the changes in rolling force and gauge during FGC were simulated. The results showed that the stability of FGC process can be improved and the influence of the FGC stand on the other upriver stands can be reduced by the proposed pass-schedule strategy.
Abstract: In order to establish a positive model of pH value control, the process with severe non-linearity and serious lag of neutralization action was studied by adding medicine in an industrial waster water neutralization control system. A novel kind of Dynamic Adaptive Nearest Neighbor Clustering (DANNC) algorithm was adopted, and a strategy by adjusting the parameter in the entire neural network to finish the task of learning and training of the neural network (NN) was applied. The NN internal model control system for pH value of neutralization, which serves as a controller of the converse model was designed, and different kinds of simulation experiments were carried. The results showed that the accuracy of the pH control system is △pH≤0.2, which satisfied the requirement of the real time adding medicine track and anti-jamming abilities in industrial application.
Abstract: An optimal approach was presented for model parameters of a support vector machine classifier based on coarse grid search combined with pattern search, in which the Jaakkola-Haussler error bound was considered as the evaluation criterion of model selection. Based on the Riemannian geometry theory, a novel conformal transformation was proposed and the kernel function was modified by the transformation in a data-dependent way. Simulated results for the artificial data set showed that the approach for automatic model selection was very effective. An application of the approach in handwritten similar Chinese characters recognition was further investigated. The experimental result showed remarkable improvement of the performance of the classifier.
Abstract: The problem of guaranteed cost control was dealt with for a class of uncertain descriptor systems, whose class is with parameter uncertainties and norm-bounded. The purpose of the problem was to design a state feedback controller such that, for all admissible uncertainties, the closed-loop descriptor systems keep regular, impulse-free and stable. At the same time an adequate level of a quadratic cost index can be guaranteed. A sufficient condition for the existence of guaranteed cost controllers was derived. It was shown that a group of linear matrix inequalities provided a parameterized representation of guaranteed const controllers.
Abstract: This paper analyzed three kinds of business models of bank and pointed out that the modern "machine-machine" model is the trend of future bank' business, but the key technical problem is to discern the clients' identity and to ensure the safety of information in transmitting. Two kinds of security control methods, the two private keys strategy and the intelligent automatic speech recognition, were presented. To the former, it is not necessary to discern the clients' identity; and to the latter, the dynamic voice, replaced the dynamic figures, was used to discern the clients' identity compared with the traditional method. Here also presented a frame description of the strategies and algorithms for solving the hard problem.
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
