Abstract: In order to study the earthquake response characteristics of a long-span steel arch bridge and the formation position and development process of plastic hinges in the bridge under soil-pile interaction,Ansys FEM software was used to comparatively discuss the effects of layered soil on the pile foundation and upper structure in consideration of structural dynamic characteristics and earthquake response under two different boundary conditions at the bottom of the bridge,i.e.,foundation consolidation and pile-soil inter-action. The results showed that the soil-pile interaction model reflected the effect of soil characteristics on the structure and it could better reveal the structural dynamic characteristics compared with the consolidation model. Using this model, the natural vibration period of structure was protracted, the period of high-order vibration modes varied significantly, and the internal force response of every part was declined, while the displacement response was amplified. But considering the effect of boundary conditions, the general trend did not change. The plastic hinges emerged on one fourth of the main girders, the girder-arch joint parts and the bottom of piers, the bottom of piers yielded firstly, while the deformation of plastic-hinge zones was still controlled in a smaller range, and the plastic hinge did not emerge on the piles.
Abstract: A comparative study was performed on the calculation methods of earthquake hydrodynamic pressure between Chinese and Japanese seismic codes of bridges through a calculation example of a deepwater pier,and the similarities and differences of both the methods were analyzed.A huge difference was obtained from both the results.The earthquake hydrodynamic pressure of a pier in deep water was calculated by numerical simulation and the distribution of pressure along the pier height was investigated.A finite element model of the 260-meter-span Ushine Bridge was built and an added mass method was applied to the model to study the influence of earthquake hydrodynamic pressure on the performance of the whole bridge. The results showed that the displacement and moment obtained by the added mass method was rather more than those without consideration of water. In the performance-based design theory of deepwater bridges and its application field, more studies were needed on the problem of the interaction between piers and water.
Abstract: Based on the comprehensive analysis of influence factors on gas emission,a relationship between the gas emission from coal faces and the influence factors was discussed.By the stepwise regression analysis method,a mathematical model for predicting the gas emission from coal faces was constructed and applied to the prediction of gas emission at the Ⅵ-24110 coal face in the No.10 Coal Mine of Pingdingshan Tian'an Coal Mining Corp.Ltd.The results showed that the model for predicting gas emission was relatively accurate.
Abstract: The photochemical degradation of four typical fatty amine flotation collectors,decyl propyl ether amine,dodecyl propyl ether amine,laurylamine,and stearylamine,in water was studied.The results of biodegradation tests(the ratio of BOD/CODCr) showed the four flotation collectors were difficult to be biodegraded.The UV/H2O2/air oxidation method was suitable for degrading fatty amine flotation collectors.This method was significant with advantages such as high degradation rate,mild reaction conditions,easy operation, and without secondary pollution. The degradation sequence which was consonant with the COD degradation sequencewas the following:decyl propyl ether amine 〉 laurylamine 〉 dodecyl propyl ether amine 〉 stearylamine. Under the conditions of the pH value of 4.5, the initial concentration of 10 rag· L-1, and 1% of H2O2 as catalyst, the degradation rate of decyl propyl ether amine reached 99.99% and the COD removal rate reached 78.06% after 15 min ultraviolet irradiation. The IR spectra of wastewater simulated with two typical fatty amine flotation collectors of decyl propyl ether amine and stearylamine were studied and the mechanism of degradation of fatty amine flotation collectors by the UV/H2O2/air oxidation method was discussed.
Abstract: The temperature curve of flue gas was fitted by the least square methods during the sintering process,and then 4 flexions of the temperature curve were calculated by solving a two-order derivative of the temperature curve.According to the migration law of each sintering zone,the temperature at the flexions can be obtained,which represents that the forefront of each sintering zone arrive at the sintering grate.As the arrival time of a flexion is known,the average speed at the forefront can be calculated.Multiplelinear regression and F-test were used to reveal the influence of sintering process parameters on the average speed at each forefront, and their relationships were proposed. Using these formulae, the BTP is stabilized by quantitatively adjusting the process parameters under the principle of energy saving and improving the average size of the sinter.
Abstract: The effect of ultrasonic power on inclusions of high carbon steel with rare earth was investigated.The results show that ultrasonic treatment in molten high carbon steel with rare earth could can disperse,refine and remove the inclusions.With the increase of ultrasonic power,the total oxygen content of high carbon steel and the average diameter of inclusions decreases evidently,the inclusions of high carbon steel will be removed in a certain degree,but the number of inclusions increases significantly.The massfraction of total oxygen content in high carbon steel, the equivalent number I and the average diameter d of inclusions in ingots are 59 × 10-6, 134 mm-2, and 2.91 μm respectively when the ultrasonic power is 100W. At the same time, the number of inclusions less than 2.31 μm is more than 43% of the total.
Abstract: Cooling rate is a key factor which affects the surface(0 to 5 mm) microstructure of a slab and the distribution of the second phase precipitates after the slab leaves the mould.In order to simulate the thermal cycle when a slab is drawn to the vertical segment,a remelting and solidification cooling experimental device was designed.The influences of cooling rate on the surface microstructure of a slab and the distribution of the second phase precipitates were investigated.It is shown that when the slab is drawninto the vertical segment at a speed of 0.8 m· min-1 and the slab surface is cooled to less than the A3 transformation temperature by intensive cooling at a cooling rate of 5℃·s-1, the surface microstructure of the slab is uniform, the second phase precipitates containing Nb and Ti are well-distributed, and film-like proeutectoid ferrite does not precipitate along the austenite grain boundaries. These help to improve the hot ductility and to alleviate the cracking susceptibility of the slab.
Abstract: The effect of temperature on stress corrosion cracking (SCC) of 316L stainless steel in high-temperature water was investigated using slow strain rate tests. The fracture morphology of 316 L stainless steel SCC specimens were analyzed with the aid of SEM. The strain-stress results showed that 316 L stainless steel exhibited SCC sensitivity in high-temperature water from 200℃to 345℃, and its brittlement increased with increase temperature, indicating that the SCC sensitivity of 316 L stainless steel was raised. The fractography analysis results also proved this susceptibility clearly. The SCC sensitive temperature of 316 L stainless steel is 250℃, at which the edge fractography morphology of the specimens presented brittle fracture characteristics.
Abstract: A series of molecular dynamics simulations for the structure transformation of liquid Cu during isothermal solidification were performed with the Tight-binding potential. Static structural information on the pair distribution functions and the coordination number distribution at different temperatures were obtained while an analysis was carried out on the possible change of short-range ordered structure of FCC crystal and its resultant types of atom pairs by means of the Honeycutt-Anderesen pair analysis technique. The results indicate that the 1551 bonds change into the 1541 bonds during solidification process and the formation of initial three-dimensional structure depends mainly on the diffusion and relaxation of Cu atoms in two directions.
Abstract: Al-La alloy samples with different compositions were prepared by a free solidification method. The results show that the dendrite structure of Al11La3 in an Al-35% La alloy is discontinuous. For demonstrating the authenticity of this structure, adopting a directional solidification method, Al-35% La alloy samples were prepared at different solidification rates. It is indicated that the dendrite structure of Al11La3 in the Al-35% La alloy obtained by directional solidification is discontinuous. The effects of composition and solidification rate on the microstructure of Al-La alloys were analyzed, and the formation mechanism of the discontinuous dendrite structure was discussed preliminarily.
Abstract: Eight-pass equal channel angular pressing (ECAP) at room temperature was successfully carried out on commercial pure Ti via route Bc, in which the samples were rotated by 90° along the vertical axis in the same direction between two extrusion passes, at an angle φ of 1200°. The microstructure and mechanical properties of the samples after different pressing passes were analyzed and tested. The results showed that after eight-pass ECAP, the tensile strength increased from 407 MPa to 791 MPa, the microhardness increased from 1 588 MPa to 2 641 MPa. the plasticity maintained well, and the elongation reached to 19%.
Abstract: Pure polyhedral Co3O4 particles were synthesized simply with cobalt chloride solution as the raw material by a spray-oxidation method under oxygen-enriched conditions.The feed solution prepared by using CoCl2·6H2O was sprayed with an air-nozzle and oxidized in the pipe high-temperature resistance furnace with compressed oxygen-enriched air as the carrier gas.The as-prepared products were characterized by X-ray diffraction analysis(XRD),Fourier-transform infrared spectroscopy(FT-IR) and scanning electron microscopy (SEM). The experimental results show that pure polyhedral Co3O4 particles are prepared successfully at the feedsolution concentration of 2.0 rnol·L -1, flow rate of 6.0 L· h-1 reaction temperature of 800℃, and spray pressure of 0.1 MPa. The electrochemical capacitive properties of the Co3O4 particles were evaluated using cyclic voltammetry and alternating current impedance methods. The capacitive properties depict that the sample Co3O4 by the spray-oxidation method is capable of exhibiting excellent capacitive performance in the 5.0 mol· L-1 KOH electrolyte.
Abstract: The electrochemical corrosion behavior of TiN coatings prepared by reactive plasma spraying was studied in seawater by SEM technology and electrochemical methods such as electrochemical impedance spectroscopy.The results showed that the corrosion potential of TiN coatings was higher than that of the substrate and the coatings had a good corrosion shielding effect on the substrate.The coatings resistance declined and capacitance increased because the corrosion medium permeated into the coating/metal interface through pinholes and microcracks immediately. Due to the products of corrosion the corrosion was restrained, but the products can not stop the local corrosion of the substrate. The electrochemical corrosion of the coatings were mainly as the result of holes in the coatings.
Abstract: The YG8 electrode was deposited on the surface of a cast steel roll by electro-sparking deposition(ESD) and formed a WC coating.The microstructure and wear resistance of the coating were investigated.The results show that the coating consists of Fe3W3C,Co3W3C,W2C and Fe7W6 phases,and is metallurgically bonded with the cast steel roll substrate.The Fe7W6 and W2C hard phases dispersedly distributed in the coating with nanosized particles.The average hardness of the coating is 1 331 HV.The coating has improved resistance performance which is 2.3 times higher than the cast steel substrate. The wear mechanism is mainly fatigue wear. Fine hard phases distributed in the coating dispersedly are the main factors leading to the high hardness and wear resistance of the coating.
Abstract: The linear polarization resistance and AC impedance techniques were applied to test the electrochemical performance of boiler water-cooling pipe steel in hydrogen peroxide solution.The microstructures of the pipe steel passivated in different conditions were observed by SEM.The experiment results show that when the mass fraction of hydrogen peroxide is 0.1%,the pH of the solution is 9.5,the mass concentration of ferrous ions is 100 mg·L-1 and the mass concentration of chlorine ions is less than 50 mg·L-1,the better passivation with H2O2 can be achieved after pickling with citric acid. An intact passive film has formed on the pipe steel and the corrosion resistance of the pipe steel is optimal.
Abstract: The quality factor Q and transmission T of two-dimensional photonic crystal microcavities,which consist of square arrays of Al2O3 rods with 5 lattice defects,were simulated by the multiple-scattering computation method.The simulation results show that the quality factor Q and the transmission T are greatly affected by the numbers of dielectric rods Lx,Ly and the radius of dielectric rods.Two-dimensional mircrocavities with high Q and large T are realized through optimizing the structure parameters.In this simulation case, when Lx=13, Ly=17, and r=0.25, the quality factor and the transmission are optimized as 49270 and 91%, respectively.
Abstract: In order to solve the problem of bending instability during slab edging,allowable rolling pressure for small-flexibility slab edging was investigated to realize slabs' stable rolling.A formula was deduced for calculating the allowable rolling pressure.Experimental and application results show that for a slab in a small flexibility range(10〈B/H〈25),the calculated values by the proposed formula are in agreement with the experimental results.
Abstract: The deformation of a lumped complete compliant slider mechanism was analyzed with pseudo-rigid-body model method.A micro-compliant slider mechanism was designed,in which the prismatic pair of it was designed and analyzed mainly.The equivalent spring force of slider pair of the designed sample was presented.Furthermore the result of analysis in pseudo-rigid-body model for the sample is given.Otherwise,the simulation analysis in the FEM method for the example is also given.The results obtained by the two methods are approximated. This indicates that the analysis and design methods are correct and feasible.
Abstract: In order to carry out equivalent study between defect risks and failure defects,the event tree analysis(ETA) method was introduced to determine the risk flow route of automobile defects.An SPN model for risk assessment was set up based on characteristics of automobile defect risks,and a 3D matrix graph was introduced to describe overall risks.According to the scattered and fluctuant characteristics of automobile defect data,a risk forecast method based on the gray theory was proposed,and a failure forecasting model of automobile defects was built with failure data as the basis of forecasting risk possibility. The precision of the failure forecasting model was proved by residual discrimination. It is shown that on gathering actual failure data from after-sales service, the gray model has a favorable applicability for forecasting risk possibility.
Abstract: Steelmaking-continuous casting production scheduling includes the drawing of a furnace charge plan and a cast plan,the allocation of time and equipments,and the dynamic adjustment to kinds of disturbances.An optimal furnace charge plan model was established based on the constraints of grade and specification and an algorithm with taboo search was used to solve the model.The cast plan was presented according to the furnace charge plan and the limitation of continuous casting.The principles of matching between converters and casters and minimizing the waiting time were used to draw the Gantt chart of static scheduling. A dynamic scheduling strategy and its algorithm were proposed for tapping tardiness in the simulation process. Simulation result shows that the strategy based on the model effectively solves the problem of tapping tardiness.
Abstract: From the perspective of precision design,a multi-objective programming mathematical model of BOF-caster matching for one production line in the steelmaking plant which produces plates and strips was proposed with production capacity,matching of rhythm time,and investment as the objective functions.Then,by using the same method and based on the mathematical model for one production line,a multi-objective programming mathematical model of BOF-caster matching for the multi production lines was established.The solving method of the model was given by an improved delaminating sequence method. Using JAVA language and through Eclipse software, the model was solved by the method of object-oriented programming. Finally, the model verified that the design scheme of Shougang Jingtang Iron and Steel Co. Ltd. was the better project.
Abstract: In order to solve the problem that material flows and energy flows both have influences on energy consumption in steel plants,a diagnosis model of energy consumption bottlenecks was established.The model uses steel ratio and process energy consumption to measure the material flows and energy flows,respectively.The function of the model is to decompose the change in energy consumption per ton steel into the changes in steel ratio and process energy consumption,so that the two factors effects can be separated, and thus the energy consumption bottlenecks can be found. The model analysis was done through three steps, correspondingly aiming at the main-process stream, the district and the process. Meanwhile, a new concept of contribution index was defined, which can indicate the effects of every factor on the energy consumption per ton steel. The model was applied to analyze the energy consumption indexes of a typical iron and steel enterprise in China using the data of energy consumption in 2001 and 2007, and the energy consumption bottlenecks in the steelmaking process were analyzed. The result shows that the restraining factors of energy consumption are the steel ratio of iron making district and steel rolling district and the process energy consumption of steel making district. At last, energy-saving measures, such as increasing the ratio of hot load and hot transportation and cutting down the fuel consumption of heating furnaces, were proposed.
Abstract: The wireless sensor network(WSN) is a typical networked embedded system.It involves in both embedded systems and networks,and is extraordinarily application-specific;therefore testing and debugging WSN becomes relatively complicated with various difficulties.Developing a "one-fits-all" platform for WSN testing and debugging is difficult to achieve.In order to efficiently test and debug the implementation of WSN application,this paper carefully analyzed previous related researches,adopted the half-practicality simulation strategy, proposed a hybrid testing and debugging system for WSN, and solved the problems that pure software simulation veils too many hardware implementation details and in-situ platforms can only provide limited visibility and controllability for both the embedded systems and the networks, thus achieved a balanced achievement.At last, an instance platform of the hybrid testing and debugging system for WSN was implemented in the field programmable gate array (FPGA);experimental results verified the correctness and validity of the proposed system.
Abstract: Two kinds of security solutions for self-behavior problems in cognitive radio networks are proposed.The solutions are based on the architecture of cluster-based cognitive radio networks.To solve the self-behavior problems that hide available channel information in the routing set-up process,first of all,trusted cluster-heads find self-nodes,and then the cluster-heads send available channel information from forward nodes to the destination node.To prevent the self-behaviors of refusing to forward packets caused by self-nodes, the nodes use a monitor mechanism to find self-nodes, in this way to avoid self-nodes as forward nodes. A routing protocol is designed to test the feasibility and effectiveness of the solutions. It is proved by theoretical analysis and simulation that self-behavior problems can serious decline network communication performance and the two solutions can effectively solve the problems of self-behavior and separately significantly improve the average capacity and the network throughput of cooperation nodes.
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
