Abstract: A mathematical model of dust movement was derived from the gas-solid two-phase flow theory. According to characteristics of the fully-mechanized coal face in mines and related survey data, numerical simulation of the dust movement rule was made with CFD software FLUENT. The result shows that most of dust moves with wind, and little of dust disperses at random. Dust control in the work face should focus on the place within 10 m under the coal mining machine near the coal wall, and wetting the coal face before coal cutting is also important for dedusting.
Abstract: The grey theory and neural network method were applied to coal and gas outburst forecast. Main controlling factors of coal and gas outburst were filtered by the grey correlation method of the grey system theory. The mathematical model and systematic structure of artificial neural network were founded to forecast the risk of coal and gas outburst. The effectiveness of the risk forecast in the outburst zone of Pingdingshan No. 8 Coal Mine was demonstrated the grey theory and neural artificial network as a new means is available.
Abstract: According to a reinforced earth retaining wall failure instance of No. 104 National Road in Shandong Province of China, the effect of pavement quality on the stability of a retaining wall under automobile loading was analyzed by numerical simulation method on the basis of analyzing the interaction mechanism between pavement and retaining wall. The result shows that pavement strength can sensitively affect the whole stability and part deformation of the reinforced earth retaining wall. The lower the retaining wall, the more sensitive the effect is.
Abstract: Composite foundation settlement of an office building in Chinese Hangzhou development region was numerically simulated with FLAC software, According to engineering practice, displacement vector and settlement analyses on the simulated results were carried out, and the calculated settlements were compared with the measured ones. On the basis of the research on the numerical simulation results and measured settlement data, main factors influencing CFG pile composite foundation settlement were summarized. It is found that composite foundation settlement was obviously affected by pile-soil interaction, pile setting, load-to-time relation and soil stress distribution.
Abstract: If people in the disaster area can make use of the disaster-reduction marking system and escape from the disaster area in time when disasters and accidents suddenly happen, the casualty and expense will be effectively reduced. Based on the investigation of medium and large subway stations domestic and oversea, some problems hidden in the disaster-reduction marking system of a domestic subway were analyzed and the optimized advices were put forward by comparing with the oversea system. The relation between the disaster-reduction marking system and the framework of emergency preplan was briefly discussed.
Abstract: H2+ ions were implanted into ilmenite at room temperature, and the microreaction mechanism during the reduction of ilmenite was investigated by transmission electron microscopy. The results indicate that during the course of reduction, metallic iron with[110] orientation is formed on ilmenite along[1431] direction, (222) or (222) plane of iron is transformed from (4264) or (4264) plane of ilmenite firstly. The structure change during the course of reduction from ilmenite to iron is a gradually changing process.
Abstract: Based on of the activity data of each component of a CaO-SiO2-Al2O3-MnO system calculated by thermodynamic software FactSage, the formation condition of plastic inclusions in the CaO-SiO2-Al2O3-MnO system was discussed by thermodynamic calculation. Comparison with some experimental data proved that this proposed method was feasible. It is shown that in order to acquire deformable inclusions in tire cord steel, the dissolved aluminum should be controlled less than 0.000 3%, and the dissolved oxygen in liquid steel must be controlled in the range of 0.002%~0.006%.
Abstract: Based on the Karrna-Rappel phase field model, the equiaxed dendritic growth and change in temperature field in a pure molten metal were numerically simulated at an initial dimensionless supercooling of 0.45. Morphological evolvement of dendrites at various anisotropic coefficients was investigated. The result shows that anisotropic coefficient significantly affects the dendrite morphology. During dendritic growth, obvious necking phenomenon appears as the anisotropic coefficienf is 0.05. The preferred growth direction of dendrites is always kept consistent with that of the highest temperature gradient.
Abstract: Cathodic polarization behavior of an X70 pipeline steel crevice in solution containing Cl- and SO42- was studied. Experimental results show that at a protection potential of -1000 mV vs CSE, with increasing crevice size the potential of the crevice tip is close to the protection potential; at the same crevice size, with the increase of protection potential the status of protection is easily reached in the crevice. Under unprotection condition, crevice corrosion can happen and the pH value of solution reduces in the crevice; under protection condition, the pH of solution can rise and in the crevice the solution alkalized.
Abstract: The effects of particle size and heating rate on the thermal stability of Sm2Fe17 alloy were investigated by TG/DTA technique. Chemical reactions during the oxidation of Sm2Fe17 alloy were confirmed with XRD and TG/DTA results. The apparent activation energy of the oxidation of Sm2Fe17 alloy was calculated by the Kinssinger equation and the reaction mechanism was deduced. The results show that the thermal stability of Sm2Fe17 alloy decreases with the decrease in particle size; and the sooner the heating rate is, the higher temperature needs for Sm2Fe17 alloy being oxidized and the less thermal it gives out. Further studies indicate that the apparent activation energies of low-temperature oxidation and high-temperature oxidation of Sm2Fe17 alloy are 162 kJ·mol-1 and 189.8 kJ·mol-1, respectively.
Abstract: A La62Al15.7(Cu,Ni)22.3 bulk amorphous alloy was prepared by spray forming. Experimental results show that the reduced glass transition temperature and super-cooled liquid region of the La62Al15.7(Cu,Ni)22.33 bulk amorphous alloy prepared by spray forming are larger than those of the melt-spun alloy with the same composition reported previously. The crystallization behavior of the as-deposited alloy was investigated by DSC and XRD in order to reveal characteristics of this technique. It shows that several phases precipitate simultaneously during the early crystallization process. When annealed at 483 K, Al and AlNi precipitates from the amorphous matrix, while La and certain unknown phase appear subsequently when the annealing temperature is 503 K. No other phase precipitates from the matrix when the alloy is annealed at 573 K. The microstructure of the crystallized sample consists of Al, AlNi, La and a kind of unknown phase.
Abstract: In order to confirm the appropriate thickness of bearing steel layer diffusion bonding on titanium alloy surface, the elastic modulus of materials was measured by Nano Indenter Ⅱ. Stress distribution and integrated distortion of the titanium alloy which bonded bearing steel layer were analyzed by finite element simulation under press stress, and the thickness of bearing steel layer was optimized and designed. The results show that when the thickness of hardened layer is 0.10-0.50 mm, the maximal equivalent stress is located the interface of titanium alloy and bearing steel layer, which can easily induce interface cracks; the appropriate thickness of bearing steel layer is 1.00-2.00 mm, and the optimal thickness is about 1.50 mm.
Abstract: A model for predicting the ballistic limit velocity was developed by combining Florence's model with the plug equation for the projectile penetration into sheet, The effects of structure parameters, including facesheet thickness, ceramic core thickness and back plate thickness, on the ballistic limit velocity of steel/ceramic/steel composite armor against 7.62 mm plain steel projectiles was investigated to optimize the armor structure and identify the validity of the model analytically and experimentally. The results reveal that the model is in good agreement with experimental values, with the relative error less than 15%, and it is optimum as the thickness ratio of ceramic tile to steel back sheet is between 1.5 to 4.5.
Abstract: A new process of diamond coatings was explored with H2, CH4 and D4 as precursors by using microwave plasma chemical vapor deposition technique. The diamond coating containing Si element was deposited on a cemented carbide substrate. This process was attempted to enhance the adhesion of the diamond coating to the substrate. The results reveal that when the flow of D4 is larger than that of CH4 the cellular structure is obtained, and the diamond coating with good quality and good adhesion is deposited with a little Si in it only when the flow of D4 is equivalent to that of CH4.
Abstract: The rolling force model is a foundation model of the process control system of a tandem cold rolling mill. Deformation resistance and friction factor have important effect on the prediction precision of rolling force. A parameter self-adaptive method was used to improve the prediction precision. During self-adapting process for the rolling force model, deformation resistance was regarded as the common property of each stand, and each stand decides its deformation resistance according to its absolute deformation grade. On this condition, friction factor was regarded as the special property of each stand, and different coefficients were given to the mathematical model for friction factor of each stand. This self-adaptive method can correct deformation resistance and friction factor at the same time. It is proved to be useful to improve the prediction precision of rolling force by practice.
Abstract: A special integral simulation model for lastic deformation of rolls and the three-dimensional a UCMW cold roiling mill was introduced based on the eplastic deformation of strips. The strip center crown and edge drop control performance of work roll bending, intermediate roll bending, work roll shifting and intermediate roll shifting were compared and analyzed through the simulation model. The influences of strip thickness, forward and backward tension, reduction ratio and resistance to deformation on the edge drop were investigated in detail. The results indicate that the strip center crown control ability of work roll bending and the edge drop control ability of work roll shifting are the strongest. The effects of all the factors on the edge drop are more than those on the center crown. It is shown that the edge of a strip is more sensitive to rolling conditions.
Abstract: In order to solve the problem of cold rolling strip surface wrinkles on the uncoiler, the stress distribution of a cold rolling strip on the uncoiler and its influencing factors were investigated by finite element method. The linkings of the uncoiler tension, strip thickness, adhesion degree and coil radius on the wrinkles were analyzed. Some measures to avoid the wrinkles were put forward by minishing the reverse bending degree of the strip on the uncoiler and the adhesion degree in the bell annealer. It is pointed that increasing the uncoiler tension can minish or avoid the wrinkles.
Abstract: In order to realize a new iron/steel interface mode which uses the same ladle from BF to BOF, the ladle needs to possess multifunction such as hot metal container, transportation, cushion function and desulphurization, etc. Based on the analysis of each function of the ladle, the difficult of each function was pointed out, and some experiments were carried out to attain interrelated parameters. The result shows that there is little difference in hot metal temperature drop between the ladle and TPC as a hot metal container and conveyance. Multifunction of the ladle can be realizable, which makes the new mold of iron/steel interface available.
Abstract: To improve the applicability of decision trees, a multi-criterion pruning method was proposed for the application of decision trees in intrusion detection, which enabled decision trees suitable for different conditions by parameter adjustment. Several parameters for describing the performance of a decision tree, such as stability, complexity and classification ability, were proposed. To meet the needs of different applications, the decision tree was expressed as a vector. Weights of different components of the vector could be adjusted according to the fact, and the required decision tree could be built gradually. Experimental results show that the proposed method can rapidly construct different decision trees according different specific environments, thus one program can be used in different conditions. The approach changes the creator of a decision tree from a programmer to a user, so the program is more suitable and the result is more reasonable.
Abstract: A new approach for hidden Markov model (HMM) training based on an improved maximum mutual information (MMI) criterion was presented and HMM parameter adjustment rules were induced. By adopting a more realistic MMI definition, discriminative information contained in the training data could be used to improve the performance of HMM and this method was also used in facial expression recognition. Facial expression feature vector flows were extracted by using the improved optical flow algorithm, and a hybrid classifier based on the improved HMM and BP neural network was designed. Experimental results show that the new method provides satisfactory recognition performance and the method is powerful for HMM parameter estimation.
Abstract: The method of generalized modeling in a large scale system was used for reference to construct a generalized model of SoftMan emotional control. The point that behavior is controlled by emotion and intelligence was presented. According to its different functions, the model of SoftMan emotional control was divided by the sense model, the thinking model and the behavior model. Both the relationship between the thinking model and the behavior model and the relationship among the sense model, the thinking model and the behavior model were showed.
Abstract: Evaluating telecom clients' credit risk rate is classifying their credit risk level. An approach based on active learning was proposed for solving the insufficient labeled data problem in building a credit risk rate classifier. The new QBC (query-by-committee, QBC) method of active learning was presented to improve the classifier's accuracy. By applying the actual telecom clients data in the experiment, the results show that the model built by the new algorithm with less labeled training data can reach the same accuracy as passive learning. This can reduce annotation cost for credit evaluation experts.
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
