Abstract: The analytical solution to the one-dimension consolidation governing equation of soil layer was deduced by use of separation of variables when the laws of permeability and compressibility coefficients with depth can be expressed as power functions. The analytical expressions of excess pore pressure isochrones and settlement-to-time relations were obtained for different drainage boundary conditions under arbitrary loading. A series of cases were presented for analyzing the law of the excess pore pressure isochrones and settlement-to-time relations when those non-homogeneous soil consolidated.
Abstract: Complex chemical industrial dewatering sludge, clay and adherent were chosen as the initial components for preparing raw aggregates of 3-6 mm in diameter used in wastewater treatment by drying, preheating, and firing processes. The effects of adherent quantity, sludge-to-clay ratio, preheating time and firing temperature on the performance of finished products were analyzed by measuring the bulk density, apparent density, specific surface area, crushing strength and wear rate. The optimal ratios of the components and the appropriate process were obtained as follows:adherent quantity 5%, sludge-to-clay ratio 4:6, preheating at 400 for 30 min, and firing temperature 1 140℃ according to the principles for making aggregates and the results of the orthogonal design method. The microstructures and characters of aggregates at different firing temperatures were observed by scanning electronic microscope.
Abstract: The sinter is consolidated by fluid liquid phase through adhering the adjacent not-molten materials, and the fluidity of liquid phase is a sintering basic characteristics of iron ore. Two new evaluation indexes, the liquid phase fluidity area based on temperature distribution (FAT) and the index of sensitivity of fluidity to temperature (ISFT), were proposed. Their corresponding calculation formulas were given to rightly master the action of liquid phase in sintering and optimize ore-matching.
Abstract: Gas volume through the sinter bed is one of the very important factors that determine the productivity of sintering. When the capacity of the exhaust fan is fixed, the increase of gas volume through the sinter bed can be only realized by the reduction of sinter bed resistance to airflow. On laboratorial conditions, the effect of bed permeability improvement under the condition of standsupport sintering was studied, and the productivity, drum index, product yield and size composition were investigated quantitatively. The results showed that applying stand-support during sintering, the productivity increased by maximum 23.15% and the drum index decreased slightly, while it still met the demand of ironmaking. The metallurgical properties of sinter were improved at the meantime.
Abstract: The width of columnar grain zone in as cast strips is mainly determined by the length of columnar grains at nip point. The columnar grain structure was simulated by FE-CA method in Calcosoft. The visualized morphology was obtained, and the calculation results fit the experimental ones well. By use of this model, the effects of process parameters on the width of columnar grain zone were studied. The results show that the width of columnar grain zone increases with increasing liquid steel surface height in the pool, but it decreases with the increase of casting temperature and casting speed.
Abstract: A kind of nickel-free high nitrogen austenitic stainless steel (0Cr17Mn11Mo3N) was prepared by powder injection molding. The effects of sintering parameters such as temperature, time and atmosphere on the relative density and nitrogen content were investigated. The results show that sintering temperature is the most important sintering parameter, with the increase of which the relative density of sintered specimens increases remarkably, whereas the nitrogen content decreases, and above 1 300 E the relative density of sintered specimens is over 99%. Sintering time has no obvious effect on the relative density and nitrogen content, and when the sintering temperature is high enough, the excellent densification of the powder can be achieved within 2 h. For the sintering of 0Cr17Mn11Mo3N stainless steel, sintering atmosphere has also a significant influence, and the higher relative density and lower nitrogen content can be obtained in N2 + H2 atmosphere than in high purity N2 atmosphere. The optimal sintering conditions of 0Crl7MnllMo3N austenitic stainless steel are as follows:1 300℃, 2 h, and flowing high pure nitrogen. Under the optimal conditions, the relative density of sintered specimens can reach 99.1% and the mass fraction of nitrogen is as high as 0.78%.
Abstract: Z3CN20-09M cast austenite stainless steel was aged at 400℃ for 100-3 000 h and the change law of nano indenter hardness and ferrite content was investigated. Its microstructure after being aged was observed by both TEM and SEM. The results showed that the thermal aging embrittlement was induced by spinodal decomposition in ferrite.
Abstract: A suppositional hot rolling line which is accordant to the actual production line of a certain steel plant was established by using the HSMM model. The ferrite size and corresponding properties of B510L steel at different heat temperatures, finishing temperatures and coiling temperatures were analyzed. Based on the simulation results, the optimal process parameters were put forward for BS10L strip steel of 6.4 mm in thickness.
Abstract: The characteristics of property nonuniformity and the cooling velocity after coiling of 700 MPa hot rolled steel plates were investigated by means of tensile test, SEM, TEM, energy spectrum analysis and hardness test, and the reasons that cause these characteristics were analyzed. The results show that the strength of the coil intermediate is the highest, but that of the outside is the lowest. There is significant difference in metallurgical structure and precipitation behavior of earbonitrides in the coil intermediate and outside samples, which is the main reason that causes property nonuniformity. The cooling velocity after coiling is an important factor that affects the metallurgical structure and precipitation behavior of carbonitrides.
Abstract: The pitting propagations of six low-carbon steels and one low-alloy steel with representative metallurgical characteristics were compared by means of occluded corrosion cell (OCC) stimulation test. Combined their metallurgical characteristic with corrosion appearance, the effect of metallurgical factors on the pitting propagation was researched. The results show that dissolved oxygen, inclusions, calcium treatment, phosphorus content and phosphoric segregation, and Ni and Cr elements in steels have important influence on the pitting propagation. A higher amount of dissolved oxygen, phosphorus, Ni and Cr elements, and calcium treatment are beneficial to restraining pitting propagation.
Abstract: Two spray coatings were prepared by thermal spray weld with two kinds of Ni-based alloy powders, named as Ni-A and Ni-B. XRD and SEM results show that the substrates of Ni-A and Ni-B spray coatings are both Ni and FeNi3, while there is few Cu in Ni-A substrate. Both in Ni-A and Ni-B coatings there are lots of secondary phases with a great proportion of Cr. Secondary phases in Ni-A have two appearances and there is about 20% Mo in them, but secondary phases in Ni-B contain no Mo. The results of high-temperature hardness test make it clear that the hardnesses of Ni-A and Ni-B are high and descend with increasing temperature. The hardness of Ni-A is higher than.the relevant hardness of Ni-B because there is about 20% Mo in the secondary phases of Ni-A.
Abstract: The injection molding of Ti-47.5Al-2.5V-1.0Cr gas-atomized pre-alloy powders was carried out. The effects of debinding on the contents of residual carbon and oxygen and the microstructure of brown parts and the influences of sintering temperature on the sintered microstructure, density and compressive property of the alloy were investigated. The results showed that the mass fractions of residual carbon and oxygen were 0. 059% and 0.12% respectively under the condition of the thermal debinding temperature of 60012, the holding time of 1 h and vacuum atmosphere. The microstructure was changed from dentritic to nearamma (NG) microstructure when the sintering temperature increased from 600℃ to 1000℃. The specimens densified rapidly at 1410-1450 12 for 1 h. When the vacuum slntering was employed, a near full density of 95% was obtained at 1450℃ after 30min holding, and the compression strength and compression ratio were 2105 MPa and 30.9% respectively, which are near to those of the cast alloy. With the sintering temperature increasing, the amount of y phase decreases gradually. The microstructure was changed from near a lamelar microstructure to a fully lamellar microstructure when the sintering temperature increased from 1410 IE to 1 450℃.
Abstract: Monolayer diamond grinding wheels and static strength samples were prepared by the HF induction brazing technology under different conditions. The normal abrasion behavior of diamond grits was found out through the comparison between the single grit's tangential and normal component force during grinding and the static compressive strength and static shearing strength of diamond grains after being brazed. As the same time, the abrasion state of diamond grits during grinding was observed. The results show that the load applied to diamond grains during grinding process is much smaller than their static strength after being brazed. The static strength of diamond grits after being brazed is influenced by vacuum degree and heating time during brazing process. The static strength is strong under the conditions of high vacuum degree and the static compressive strength loses much under the conditions of long brazing time. Otherwise, the static shearing strength is associated to an optimal brazing time. Diamond tools fabricated by the HF induction brazing technology meet the needs of normal grinding fields. Most of the grits are micro-broken during grinding and only a few of them are pulled-out or broken-off.
Abstract: A three-dimensional steady simulation of the flow in the four-branch pipe of a controlled cooling device was carried out by the numerical simulation calculation method of finite element coupling field. The effect of nozzle pipe diameter, nozzle pipe height, branch pipe diameter, and inlet velocity on the flux uniformity at the nozzle pipe outlet was analyzed. The result of simulation show that nozzle pipe diameter, branch pipe diameter and inlet velocity have a great influence on the flux uniformity at the nozzle pipe outlet, but nozzle pipe height has a little influence on it.
Abstract: The spindle of a CSP mill was researched as continuous distributed mass. The spindle's angle, self-weight, mass unbalance and damp were all considered as influential factors. The equations of lateral-torsional coupling vibration for the spindle were established based on the dynamical theory to theoretically interpret field testing data. According to the differential equation of the mathematic model, the following conclusions can be drawn:if unbalance exists, the lateral vibration and torsional vibration are coupled distinctly; if unbalance does not exist, the torsional vibration can affect the lateral vibration, but the lateral vibration has not any effect on the torsional vibration.
Abstract: A set of Burmester curves can present an infinite number of rigid-body guidance solutions for given four rigid-body poses. It is difficult for designers to synthesize the best linkage through rapidly and exactly select points that ensure to satisfy every design condition. First, an infinite number of rigid-body guidance solutions were expressed as finite solution regions in this paper. Based on initial analysis of solution regions, the mechanism property graph was computed to make designers find out the revolved mechanism's information, such as type, minimum transmission angle, link-length ratio, defects, and so on. Second, after the design constraints were considered and imposed, the feasible solution regions which avoid aimlessness in choosing positions can be calculated. Finally, on the feasible solution regions or the one of interest, property analysis graphs were displayed, along with which the optimized rigid-body guidance solution produces.
Abstract: Aiming to a method for the synthesis of silicon nitride powder by direct nitridation process based on fluidization technology, a two-dimensional mathematical model of thermal process in a suspended bed was established, the thermal process was simulated based on the commercial CFD software FLUENT, and the effects of the flow velocity of nitrogen gas, the ratio of particle to gas and nitridation temperature on the temperature of the bed and the conversion rate of silicon were analyzed. The results show that the errors between simulation and experimental values are less than 5% and the model can be used to predict the thermal process in the suspended bed. Under the experimental conditions in this study, when the silicon powder with a particle size of 2.7 μm is used as raw materials, with a nitridation temperature of 1380℃ and nitridation time of 54.5 s, the conversion rate of silicon is 22.5%. Theoretical predictions suggest that if the nitridation temperature is increased to 1450℃ and the nitridation time is extended to 7.1 min, the conversion rate of silicon and the purity of silicon nitride should reach 98.6% and 98%, respectively.
Abstract: A theoretical analysis of boundary layer flow on the continuous moving surface of power law fluids was carried out based on the theory of dimensional analysis of the fluid dynamics. The magnitude and the influencing factor of the laminar boundary layer thickness were obtained. The governing equations of mass and momentum were transformed into the dimensionless form by introducing dimensionless variables. The flow fields of different power-law index fluids with different velocity ratio parameters were presented numerically. The characteristics of the flow and the influence of power-law index and velocity ratio parameter on the flow were analyzed. The results show that the dimensionless velocity and shear stress depend not only on the velocity ratio parameter of the plate, but also on the power law index.
Abstract: A kind of slab designing problem was brought forward, in which the weight of slabs is fixed and the customer order demand specifications of weight and width are interval values. A multi-objective model to minimize the number of slabs and the total surplus weight was built. Based on the idea of the order-slab matrix and the compatible set of slabs, a two-stage optimal algorithm was proposed to solve the problem. In the algorithm, the first stage is to minimize the number of slabs, and the second stage is to minimize the total surplus weight. For this algorithm, the optimal nature was proved theoretically and an application case was given based on practical data.
Abstract: A new pheromone-based crossover operator of genetic algorithm for the traveling salesman problem was proposed, and the working process of the operator was analyzed when constructing offspring. When constructing offspring, the proposed operator utilizes both local and global irdormation. The local information includes edge lengths and adjacency relations, while the global information is stored as pheromone trails. The proposed operator was tested in a pure genetic algorithm framwork using the TSP benchmark instances. Experimental results show its better performance in both of speed and accuracy than other well known crossover operators.
Abstract: In order to solve the difficulties of tendency to local optima in conditional optimization algorithms for back propagation neural network (BPNN), with improvements in the strategy for updating the particle's velocity and location, this paper proposed a new back propagation neural network modeling method based on improved particle swarm optimization. The data from sinc function, Boston housing problem and the real strip hot-dip galvanizing production in an iron and steel corporation were used for verification. The results show that, compared with the standard BPNN and support vector machine algorithms, the proposed method can effectively help the BPNN to get a better regression precision and prediction performance.
Abstract: An improvement of the fast Fourier transform (FFT) algorithm was presented, which uses the fast attenuation characteristic of Fourier transform. This algorithm can effectively eliminate leakage component spectrum, realize non-rounded harmonic precision testing and overcome the shortcomings of the traditional FFT, only by a simple transformation of FFT. Because this algorithm is more similar to but simpler than the form FFT in algorithm structure, it is more suitable for storage on microprocessors which are limited-resource. A harmonic detection device based on digital signal processing (DSP) was designed to prove that the algorithm is applied to the convenience of microprocessors.
Abstract: Using the ear and face possessing of special physiological correlation under the same pose condition as the research object, a muhimodal recognition method based on kernel canonical correlation analysis (KCCA) was proposed to solve the problem of information loss resulted from sharp pose change. In the method, the normalization and centering methods were used to preproeess ear and face datasets and the nearest neighbor method was used to classify. Experimental results show that KCCA can availably overcome the effect of sharp pose change. Compared with the single biometric, the recognition rate improves remarkably.
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
