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15 February 2014, Volume 35 Issue 2 Previous Issue    Next Issue
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Information & Control

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Kane Dynamic Equations Based on Screw Theory for Upper Limb Rehabilitation Robot LI Hongru， JIANG Zhibin， WU Wei 2014, 35 (2):  153-157.  DOI: 10.12068/j.issn.1005-3026.2014.02.001 Abstract ( 938 )   HTML   PDF (560KB) ( 999 )   Based on the screw theory， the concepts of motion screw， force screw and partial velocity screw were introduced. Then Kane dynamic equations were derived for an upper limb rehabilitation robot with 5 DOF. Simulation results show that dynamics analysis for the robot based on the screw theory is more concise and explicit than that based on the DH method in which local coordinate systems are used. The solution of Kane equations only involves addition， subtraction and multiplication， so the method has higher calculation efficiency than nonlinear Lagrange and NewtonEuler dynamic equations and is easier to implement real time control. The robotic joint curves of angular displacements， angular velocities， angular accelerations were studied by simulation from initial configuration to ready configuration. The conclusion validates the correctness and effectiveness of Kane equations based on the screw theory. References | Related Articles | Metrics

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State Feedback Stabilization for Switched Singular Networked Control Systems LIU Lili， ZHANG Qingling， DU Zhaoping 2014, 35 (2):  158-161.  DOI: 10.12068/j.issn.1005-3026.2014.02.002 Abstract ( 644 )   HTML   PDF (300KB) ( 572 )   The switched singular networked control systems with timedelay are considered， and the modeling problem is discussed. Supposing that the sensor node is timedriven， the controller and executor are eventdriven， and the networkinduced delay is less than one sampling period， the system can be modeled as a linear discrete switched system with delay. By the construction of Lyapunov function and multiple Lyapunov functions， the stability of the system can easily be assessed. Meanwhile， the robust asymptotic stabilizing state feedback control law is proposed for the switched singular networked control system. References | Related Articles | Metrics

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An Improved Robust Stability Analysis Technique for Linear Networked Control Systems CHEN Xinwei， WU Xiangyu， ZHAO Jun 2014, 35 (2):  162-165.  DOI: 10.12068/j.issn.1005-3026.2014.02.003 Abstract ( 595 )   HTML   PDF (310KB) ( 526 )   Considered are the stability problem of the uncertain linear networked control systems with transmission delays and packet dropout. The networked control system is transformed into an uncertain linear system with transmission delay. Then，the stability analysis of the timevarying system with delay and uncertain structures is given by using a new Lyapunov function with the lower delay bound， and the LMI conditions are derived related to the delay bound. Finally， numerical examples are given to illustrate the less conservation of this method. References | Related Articles | Metrics

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Modeling of Hysteresis Behavior for Micro/Nano Piezoelectric Actuator WEI Yangjie， WU Chengdong 2014, 35 (2):  166-169.  DOI: 10.12068/j.issn.1005-3026.2014.02.004 Abstract ( 713 )   HTML   PDF (553KB) ( 749 )   In order to precisely measure the actuation property of a piezoelectric actuator(PA) on micro/nano scale， an improved subpixel block matching algorithm with an optimal block size was used to measure micro/nano displacement， and combined with the Preisach model， a new hysteresis modeling method was proposed. First， the relationship between block size and measurement precision was investigated and the optimal block size was obtained with respect to a standard block. Then， the Preisach model was introduced to model the hysteresis behavior of a piezoelectric actuator. Finally， experiments with a nanometer movement platform system showed the feasibility and validity of the proposed method. References | Related Articles | Metrics

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Parameters Optimizing of LSSVM Based on Black Hole Algorithm WANG Tong， GAO Xianwen， JIANG Zijian 2014, 35 (2):  170-174.  DOI: 10.12068/j.issn.1005-3026.2014.02.005 Abstract ( 1501 )   HTML   PDF (463KB) ( 1106 )   Black hole(BH) algorithm is used to search the optimal parameters of least squares support vector machine(LSSVM). Black hole phenomenon in the nature is simulated in BH algorithm， which has the ability to attract the stars moving to it and absorb them in a certain range. During BH algorithm running the entire space is searched through the moving stars and the black hole is considered the optimal solution.In the simulation experiment the twodimensional function is predicted by BHLSSVM and PSOLSSVM respectively. The simulation results show that BH algorithm has excellent capability to search optimal parameters of LSSVM， and BHLSSVM has better capability and higher predictive accuracy. References | Related Articles | Metrics

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Comprehensive Analysis of Fatigue Driving Based on EEG and EOG WANG Fuwang， WANG Hong， LUO Xu 2014, 35 (2):  175-178.  DOI: 10.12068/j.issn.1005-3026.2014.02.006 Abstract ( 1246 )   HTML   PDF (434KB) ( 1953 )   The EEG and EOG have significant changes when drivers are fatigued. So these two types of signals can be used to analyze fatigue driving. Firstly， the α rhythm was extracted from drivers’ EEG signals using wavelet packet decomposition and its relative power spectrum P was calculated. Then the blinking characteristics of the EOG signals contained in F7 and F8 channels were analyzed and the interference signals were removed using the Pearson correlation coefficient. Finally， the blinking signals were identified using BP neural network and the blinking rate was calculated. The results show that using the comprehensive analysis of EOG and EEG can accurately identify the blinking signals and correctly detect the changes of driver fatigue state. References | Related Articles | Metrics

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A Shared Path Protection Mechanism Based on Delay Constraint in Optical Network LI Jie， WANG Xingwei， HUANG Min 2014, 35 (2):  179-183.  DOI: 10.12068/j.issn.1005-3026.2014.02.007 Abstract ( 583 )   HTML   PDF (442KB) ( 632 )   To satisfy the request of low delay and survivability for realtime services in the optical network， a shared path protection mechanism was proposed based on delay constraints in the optical network. For meeting the delay requirements of services， the node load and wavelength conversion were used as the factors which have great effect on processing delay， and the length of a link was regarded as the factor which would influence the propagation delay.A routing algorithm for the work path of services was designed and a wavelength assignment scheme was proposed based on the influence of wavelength conversion in the time delay of services to reduce the number of wavelength conversion. In terms of survivability， a protection algorithm and the corresponding wavelength assignment scheme were designed based on the shared path protection and low delay requirement of realtime services. Simulation results show that the proposed mechanism is both feasible and effective. References | Related Articles | Metrics

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A TwoStage Algorithm for Project Scheduling Problems with Multiskilled Workforce Constraints WANG Yifan， LIU Shixin， CHEN Di 2014, 35 (2):  184-189.  DOI: 10.12068/j.issn.1005-3026.2014.02.008 Abstract ( 578 )   HTML   PDF (381KB) ( 959 )   A twostage optimization algorithm was represented to solve one type of project scheduling problems with multiskilled workforce constraints(PSPMSWC). The model of PSPMSWC was proposed and decomposed into submodels corresponding to the algorithm. By using hybrid genetic local search(GLS) and CPLEX optimization software， a strategy to iteratively solve the submodels in sequence was proposed to ensure that all the instances could be solved successfully. Instances were randomly generated from a standard problem library and utilized to test the performance of algorithm experimentally. Computational results show that all of instances can be solved efficiently， with some of instances having the optimal values. Therefore， the twostage algorithm is proved to be a good method to solve PSPMSWC with practical significance. References | Related Articles | Metrics

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Memetic Algorithm for Crane Scheduling Problem with Spatial and Temporal Constraints WANG Xu， LIU Shixin， WANG Jia 2014, 35 (2):  190-194.  DOI: 10.12068/j.issn.1005-3026.2014.02.009 Abstract ( 629 )   HTML   PDF (446KB) ( 864 )   A crane scheduling problem is a multimachine，multitask and NPhard problem. For the problem in the steelmakingcontinuous casting production process， a model was proposed to minimize the waiting time of molten steel， with temporal and spatial constraints considered. An improved Memetic algorithm was developed to solve the model， in which individual decoding based on task allocation rules and conflicts eliminating rules， PPX crossover operator and local search(LS) operator were designed， and it was also compared with the genetic algorithm. The solution to the model with the improved algorithm for a practical problem showed that the waiting time was reduced by 1667% at most with high stability， in comparison with the genetic algorithm. References | Related Articles | Metrics

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Research on Correlation Between Internet Measurement Levels and Dynamic Nodes Characteristics ZHAO Hai， LIU Yiwen， AI Jun， WANG Jinfa 2014, 35 (2):  195-198.  DOI: 10.12068/j.issn.1005-3026.2014.02.010 Abstract ( 565 )   HTML   PDF (571KB) ( 491 )   Introducing network science theories， the evolution mechanisms of different network scales were analyzed based on lots of data provided by the CAIDA project. As to the topologies of IPlevel and ASlevel， the correlation between the two levels and the characteristics of dynamic nodes were analyzed， including the dynamically changing proportion of birth/death nodes， preferential attachments and the number of stable attachments. The conclusions are as follows: firstly， IPlevel nodes are more active; secondly， the evolution of IPlevel nonpreferential attachments is more stable， and thirdly， the number of IPlevel stable attachments is much greater. The evolutions of the dynamic nodes in different measure levels are different in essence， which can provide a valid basis for understanding the Internet evolution mechanism. References | Related Articles | Metrics

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Cachebased Shortest Path Query in Road Network LI Xiaohua， WANG Shimeng， YANG Xiaochun， YU Ge 2014, 35 (2):  199-203.  DOI: 10.12068/j.issn.1005-3026.2014.02.011 Abstract ( 664 )   HTML   PDF (435KB) ( 632 )   Based on the analysis of the shortcomings of the existing methods for querying shortest path in road network using cache， a new cachemanaging method was proposed. When the cache’s size was limit， the shortest paths which were expected to answer different queries as much as possible were selected effectively using the method and stored in the cache. The cache benefit model was proposed， with the cache structure designed. The experiments on real data set and the analysis demonstrate that the proposed approach can hit more paths in the cache， which results in the average high performance compared with the existing approaches. References | Related Articles | Metrics

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Relaxation Factorbased FastICA with Higher Order Convergence JI Ce， WANG Yanru， SHA Mingbo， YANG Zhengyi 2014, 35 (2):  204-207.  DOI: 10.12068/j.issn.1005-3026.2014.02.012 Abstract ( 901 )   HTML   PDF (527KB) ( 712 )   High order FastICA(fast independent component analysis)algorithm has the characteristics of simple form and quick convergence. However， the algorithm is sensitive to its initial value which affects the convergence effect and even results in nonconvergence if it is not chosen appropriately. In order to solve this problem， a relaxation factor is introduced into high order Newton iterative method. Through the appropriate correction， the improved high order FastICA algorithm can be obtained， which can not only guarantee the convergence speed， but also effectively overcome the initial value sensitivity problem. Applying the algorithm to the separation experiment of speech signals， the result shows that the proposed algorithm effectively separates the mixed signal，and reduces the dependence on the initial value. References | Related Articles | Metrics

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A Gain Correction Method Based on Threshold for FlatPanel Detector XIAO Dayu， CAI Pengfei， LI Hong， KANG Yan 2014, 35 (2):  208-211.  DOI: 10.12068/j.issn.1005-3026.2014.02.013 Abstract ( 900 )   HTML   PDF (407KB) ( 1004 )   In order to remove the stripes and ring artifacts caused by the defects of the detector and to improve the reconstructed image quality from flat panel detector in dental CT， a new gain correction method based on threshold was proposed.The air images were collected under the same radiation conditions as the normal scan to calculate the gain coefficient matrix by the normalization method. What’s more，the attenuation of the object was taken into account. With the matrix of the gain coefficient and the result of the threshold judgment， the gain correction was performed on each pixel of the image one by one according to the calculated gain coefficient matrix. Experimental result showed that a large number of stripes and ring artifacts in the image were effectively removed after the correction， with no stripes introduced again. The quality of the reconstructed image was improved significantly. References | Related Articles | Metrics

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Auditory Characteristicsbased Speech Coding Strategy in Cochlear Implant YANG Dan， XU Bin， LI Feng， WANG Xu 2014, 35 (2):  212-216.  DOI: 10.12068/j.issn.1005-3026.2014.02.014 Abstract ( 544 )   HTML   PDF (567KB) ( 982 )   For the limitations of speech coding strategy in cochlear implants， a coding strategy was proposed based on auditory characteristics. For the bandpass filter and envelope detector stage in the proposed strategy， Gammatone filterbanks model and Meddis inner hair cell(IHC)model were used respectively. For channel selection stage， a psychoacoustic masking effects model was used. The strategy using MATLAB was simulated，and 8of22 channel coding strategy was realized. The results showed the proposed strategy had more stability and robustness than other strategies， such as CIS (continuous interleaved sampling)and ACE (advanced combination encoder). References | Related Articles | Metrics

Materials & Metallurgy

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Effects of ColdRolling Process on Primary Recrystallization Texture of Grain Oriented Silicon Steel WANG Yang， XU Yunbo， ZHANG Yuanxiang， WANG Guodong 2014, 35 (2):  217-221.  DOI: 10.12068/j.issn.1005-3026.2014.02.015 Abstract ( 759 )   HTML   PDF (949KB) ( 799 )   Two common coldrolling processes of grain oriented silicon steel and the effects of the single stage cold rolling and twostage cold rolling with intermediate annealing processes on the primary recrystallization microstructure and texture were investigated. The results revealed that for the grain oriented silicon steel prepared under the twostage cold rolling process with intermediate annealing with Cu2S as the main inhibitor， the average grain size of the primary recrystallization microstructure was 181μm，the volume fraction of Goss grain was 06%， the ratio of coincidence site lattice(CSL，Σ 5+ Σ 9)and high energy grain boundaries(20~45° misorientation angles)which have the higher migration than the conventional boundaries were 18% and 504%， respectively. Compared with the single stage cold rolling process， the primary recrystallization grains of the twostage cold rolling with intermediate annealing were finer; moreover， the proportion of Goss grain and high migration boundaries were larger， which were favorable to the secondary recrystallization occurrence of the Goss grain. References | Related Articles | Metrics

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Effects of Cooling Rate on Microstructure and PhaseTransformation Temperature of 5Ni Steel WANG Meng， SUN Mingxue， LI Chenggang， LIU Zhenyu 2014, 35 (2):  223-227.  DOI: 10.12068/j.issn.1005-3026.2014.02.016 Abstract ( 838 )   HTML   PDF (1491KB) ( 928 )   Using the FormastorFⅡphase transformation thermal expansion instrument， the static CCT diagram and critical points Ac1 and Ac3 of 5Ni steels were investigated in order to provide the basis for the process plan of the heat treatment. Microstructures， Vickers microhardness and composition segregation were investigated by means of durometer， optical microscopy(OM)， scanning electron microscope(SEM) and electron probe microanalyzer(EPMA). It was found that with the increase of the cooling rate，microstructures of the specimens transformed from polygonal ferrite and pearlite to bainite and martensite. The CCT diagram revealed that the critical cooling rate need exceed 20 ℃/s to avoid ferrite and bainite transformation in quenching treatment. The composition segregations of Ni were found under different cooling rates that were beneficial to the formation of retained austenite during the tempering，which improved the toughness of 5Ni steels. References | Related Articles | Metrics

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Evolution of Si Morphology in Mg Containing Eutectic AlSi Alloy Ingot During Heating Process ZHAO Gang， SHI Xiangyu， TIAN Ni， ZUO Liang 2014, 35 (2):  228-231.  DOI: 10.12068/j.issn.1005-3026.2014.02.017 Abstract ( 689 )   HTML   PDF (629KB) ( 572 )   The evolution of the morphology of eutectic Si in the DC casting Al127Si07Mg ingot with 110mm diameter during the salt bath heat treatment at 485℃ was studied by means of optical microscope(OM)， laser scan confocal microscope(LSCM) and scanning electron microscope(SEM).The results showed that by OM the section morphology of the eutectic Si in the ingot of DC casting Al127Si07Mg alloy was the mixture of spot and strip，but its 3D morphology was coral like structure. The corallike Si coarsened when the semicontinuous casting ingot was in the early stage of the reheating and holding treatment， furthermore， some of the long rodlike eutectic Si changed its morphology into the continued gourdlike shape which then broke up into granules getting coarsening and spheroidization afterwards， when the holding time of the heat treatment was prolonged The diameter of the eutectic Si particle and the holding time were in accordance with a power of 229 ~ 267 relationship during heating and holding the ingot at 485℃. References | Related Articles | Metrics

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Preparation of WO3 Films with Nanoporous Structure MEI Yudong， CAI Jiajia， LI Song， QIN Gaowu 2014, 35 (2):  232-235.  DOI: 10.12068/j.issn.1005-3026.2014.02.018 Abstract ( 653 )   HTML   PDF (814KB) ( 575 )   Thin films of WO3 nanoporous structure grown on tungsten substrates using the anode oxidation method were studied. The effects of anodic oxidation conditions such as the concentration of NH4F in the electrolyte， the applied voltage and the heat treatment schedule on the surface morphologies of the WO3 film were investigated. The preparation conditions to form nanoporous WO3 film with good microstructure were optimized. It was found that the films prepared in electrolyte containing 005 wt.% NH4F for 20min with the applied voltage of 60V at 20℃ exhibited the expected nanoporous morphology with self assembled nano multilayer mesh structure closely packed. In addition，after heat treated at 450℃ for 3h with a heating rate of 5℃/min， the amorphous films crystallized without changing their asobtained nanoporous structures. References | Related Articles | Metrics

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Physical Simulation of Bottom Powder Injection in Combined Blown Converter TANG Biao， HE Yibo， ZOU Zongshu， YU Aibing 2014, 35 (2):  236-240.  DOI: 10.12068/j.issn.1005-3026.2014.02.019 Abstract ( 749 )   HTML   PDF (589KB) ( 677 )   A cold model of top and bottom blown converter with bottom powder injection was established to investigate the powder distribution and penetration ratio in melt bath. Water， saltcoated hollow alumina particles and vacuumpump oil were used to simulate liquid steel， limestone powder and slag， respectively. The powder distribution under different bottom blowing arrangements was studied by using the image processing method to find out the optimum bottom tuyere arrangement. With the optimum bottom tuyere arrangement， the effects of solid/gas ratio and powder particle size on powder penetration ratio were studied. The results show that the powder penetration ratio increases with the increase of solid/gas ratio and powder particle size. Under the laboratory conditions， the solid/gas ratio of 30~40 and the powder particle size 0212~0380 mm are suggested. References | Related Articles | Metrics

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Pyrolusite Leaching Reactions in FeS2MnO2H2SO4 System FENG Yali， ZHANG Xu， LI Haoran， YANG Zhichao 2014, 35 (2):  241-244.  DOI: 10.12068/j.issn.1005-3026.2014.02.020 Abstract ( 501 )   HTML   PDF (466KB) ( 724 )   The process of pyrolusite leaching in FeS2MnO2H2SO4 system and the effect of FeS2 reaction pattern on leaching efficiency of MnO2 were experimentally studied. The concentrations of Mn2+，Fe2+，Fe3+ and pulp potential were monitored， and the process was divided into some phases and then analyzed. The results show that the leaching rate ratio of Mn2+ to Fe3+ is different in different phases， which shows that different reactions occurred in the pulp in different phases， leading to obvious difference in the utilization ratio of pyrite. The monitoring of pulp potential shows that high potential is favorable to the leaching of pyrite and also speeding up the leaching rate of MnO2. References | Related Articles | Metrics

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Experimental Study on Waste Heat Recovery for Metallurgical Slag Particles LIU Junxiang， YU Qingbo， XIE Huaqing， QIN Qin 2014, 35 (2):  245-248.  DOI: 10.12068/j.issn.1005-3026.2014.02.021 Abstract ( 865 )   HTML   PDF (588KB) ( 723 )   In order to solve variuous problems in recovering waste heat from high temperature metallurgical slag particles by cold air， the technique that the waste heat of metallurgical slag particles is directly recovered by gravity bed waste heat boiler to produce steam was proposed. The experiment apparatus for gravity bed waste heat boiler was established. The influences of Reynolds number of water in heat exchange tubes， slag particle velocity and the initial temperature of slag particles on heat exchange were investigated. The results show that the heat exchange resistance of slag particles is about 55~100 times as much as that of water in tubes.The total heat exchange resistance is determined by heat exchange resistance of slag particles， and the Reynolds number of water in heat exchange tubes has little influence on total heat exchange coefficient and waste heat recovery rate. The heat exchange coefficient of slag and the waste heat recovery rate increase gradually with the increases in velocity and initial temperature of slag particles. References | Related Articles | Metrics

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Electrodeposition of Manganese Dioxide on TiIrO2 Anode in Acidic Nitrate Medium WANG Weida， FENG Yali， LI Haoran， CAI Zhenlei 2014, 35 (2):  249-252.  DOI: 10.12068/j.issn.1005-3026.2014.02.022 Abstract ( 655 )   HTML   PDF (588KB) ( 627 )   The phase structure and the electrochemical property of TiIrO2 electrode were studied with Xray diffraction analyzer and electrochemical workstation. The optimum conditions were obtained for manganese dioxide electrodeposition in acidic nitrate medium with TiIrO2 electrode as the anode. The quality property of the product was analyzed. The results show that TiIrO2 electrode is better in antipassivation and electrocatalytic activity than Ti electrode， so it is favorable for the electrodeposition of manganese dioxide. Under the conditions of 09mol/L manganese ion concentration， 03mol/L nitric acid concentration，90℃ electrolysis temperature and 60A/m2 current density， the current efficiency and the power consumption of the manganese dioxide product can reach 9956% and 5809kW·h/t， respectively. The quality of manganese dioxide product can meet the standard for electrolytic manganese dioxide in battery industry and the crystalline phase is γMnO2. References | Related Articles | Metrics

Mechanical Engineering

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Research on Design of Pitch Profile of Backingoff Cam LIANG Song， WANG Xu， WANG Xiaoqiong， ZHANG Yimin 2014, 35 (2):  253-256.  DOI: 10.12068/j.issn.1005-3026.2014.02.023 Abstract ( 691 )   HTML   PDF (684KB) ( 935 )   The method for designing the pitch profile of a cam for a backingoff lathe was studied， with the Hermite return curve of the cam designed. The principle of machining the gear hob’s back surface using a backingoff lathe was outlined. The parametric equation of cubic Hermite return curve was proposed based on the differential geometry theory and Hermite polynomial interpolation combined with the curve boundary conditions. Taking the design of a backingoff cam as an example， the difference between the Archimedes return curve and Hermite one was compared and the influence of different types of return curves on machining process was analyzed， showing that the Hermite curve was better. To increase the design efficiency， the C language was used to program the pitch profile of the cam， and the opensource software package gnuplot and LaTeX were used to show the design graph. References | Related Articles | Metrics

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Analysis of Dynamic Response and Sensitivity of Gear Systems Based on Stochastic Perturbation Theory HU Peng， LU Jinchang， ZHANG Yimin 2014, 35 (2):  257-262.  DOI: 10.12068/j.issn.1005-3026.2014.02.024 Abstract ( 558 )   HTML   PDF (683KB) ( 718 )   A multistage gear transmission dynamic model was developed， where the nonlinearity factors such as timevarying stiffness， transmission error， and backlash were considered. This model took the relevant physical， geometrical and load parameters as random variables. When the random section of the variables was much smaller than the determining section， the kinetic equations were expanded to the first order at the mean value of the random parameter vector by Taylor series expansion theorem using the stochastic perturbation theory. Then the finishing equations were solved numerically， with the first fourthorder moment of the system response obtained based on the Kronecker product algebra and matrix differential theory. To assess the stability of the system， the first secondorder moment of the dynamic transmission error of a gear pair was solved and compared with the Monte Carlo method. At the same time，the dimensionless mean sensitivity of dynamic transmission error to the random parameters was analyzed. The results provide a basis for improving the system stability. References | Related Articles | Metrics

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A Prestressed Component Mode Synthesis Method for Dynamics Analysis of BliskShaft Integrated Rotor KOU Haijiang， YUAN Huiqun， LI Yan， YANG Wenjun 2014, 35 (2):  263-267.  DOI: 10.12068/j.issn.1005-3026.2014.02.025 Abstract ( 831 )   HTML   PDF (766KB) ( 796 )   Dynamicallty analyzing a bliskshaft integrated rotor has to solve the problem of large scale finite element mesh. So， a prestressed component mode synthesis method was proposed， with which the static and rotating frequencies of the first two blisks were calculated. The principle for choosing the modal truncation number， which influenced the accuracy of the dynamics analysis of the bliskshaft integrated rotor， was presented. By comparing the static frequency with rotating one of the bliskshaft integrated rotor， the effect of rotation on the modal characteristics of the system was figured out. Modal analysis of the blisks and the bliskshaft integrated rotor indicates that the rotating frequency corresponding to the blade modes is reduced due to the effect of the shaft，and the coupling modes among the blades， disk and shaft are found， which illustrates the importance of the dynamics analysis of bliskshaft integrated rotor with large scale finite element mesh. References | Related Articles | Metrics

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Effects of Processing Parameters for Novel Point Grinding Wheels on Surface Quality YIN Guoqiang， GONG Yadong， WANG Chao， WEN Xuelong 2014, 35 (2):  273-276.  DOI: 10.12068/j.issn.1005-3026.2014.02.027 Abstract ( 725 )   HTML   PDF (663KB) ( 521 )   A vitrified bond CBN point grinding wheel with coarse grinding area slope angle θ was proposed， which owned higher removing rate and machining accuracy compared with the conventional wheels. The design and manufacture principle of the novel grinding wheel was studied. Stepped shafts of QT700 were ground using the wheels with different coarse grinding area slope angle θ under the conditions of a series of grinding parameters. The surface qualities of the workpieces were observed by means of VHX1000E microscopic system and Micromeasure system， with the surface roughness measured. The effect of the grinding parameters on surface roughness was investigated， and the surface roughness of workpieces， which were ground using the wheels with different slope angle θ under identical conditions of the grinding parameters，was compared. References | Related Articles | Metrics

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Spatial Coordinates Determination of Bogie’s Gravity Center WANG Xiugang， SU Jian， CAO Xiaoning， TAN Fuxing 2014, 35 (2):  277-281.  DOI: 10.12068/j.issn.1005-3026.2014.02.028 Abstract ( 527 )   HTML   PDF (987KB) ( 759 )   Relying on the bogie’s parameters test bench developed by Jilin University， the spatial coordinates determination method of the bogie’s gravity center was put forward based on the moment balance principle. The test models for spatial coordinates were also established. The longitudinal and the lateral coordinates were tested with keeping the bogie still. But when test the vertical coordinate， the bogie should be inclined via the actuators of the test bench to analyze the moment balance at an angle. The inverse displacement analysis model of the multiplesixDOF simulation platform with complex coupling motions was established， and the vertical coordinate was tested based on the coordinated control commands of the actuators. Coordinates of the gravity center of a certain bogie were measured and compared with the theoretical coordinates. The result shows that measured values are consistent with the theoretical ones， which proves the accuracy and feasibility of the test method. References | Related Articles | Metrics

Resources & Civil Engineering

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Kinetics During Coalbased Reduction Process of Fe2O3SiO2 System WANG Zehong， LI Guofeng， GAO Peng， HAN Yuexin 2014, 35 (2):  282-285.  DOI: 10.12068/j.issn.1005-3026.2014.02.029 Abstract ( 547 )   HTML   PDF (414KB) ( 709 )   The kinetics during coalbased reduction of Fe2O3SiO2 system was studied isothermally and nonisothermally. The isothermal experiments showed that reduction degree and reduction rate increased with the rise of reduction temperature in a certain range， which was beneficial to the gasification of coal. The coalbased reduction reaction of Fe2O3SiO2 system accorded with AvramiErofeev kinetic model， and the reaction was controlled by the process of nucleation and development of iron particles. The apparent activation energy and preexponential of isothermal coalbased reduction process were 23533kJ/mol and 322×107min-1 respectively. The nonisothermal experiments showed that coalbased reduction reaction started at 400℃ and accelerated after 700℃ then reached equilibrium eventually. The apparent activation energy and preexponential of main reaction stage were 23866kJ/mol and 104×107min-1 determined by nonisothermal method. References | Related Articles | Metrics

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Floatability Study of Diatomite，Albite and Quartz GAO Ying， HAN Yuexin， CHEN Xiaolong， ZHU Yimin 2014, 35 (2):  286-289.  DOI: 10.12068/j.issn.1005-3026.2014.02.030 Abstract ( 707 )   HTML   PDF (539KB) ( 640 )   The flotation behavior of diatomite， albite and quartz was studied using laurylamine as the collector， and the acting mechanism of the collector with the minerals was analyzed by Zeta potential measuring and FTIR spectrum analyzing methods. The mineral flotation test results indicate that the recoveries of the albite and quartz were above 92 wt.% and 97 wt.%， and the recovery of diatomite was below 5 wt.%， in a slurry of pH ranging from 55 to 105 at a laurylamine concentration of 238×10-4mol/L. Zeta potential analysis indicates that the action between the laurylamine and the diatomite surfaces in a slurry of pH ranging from 55 to 105 is weaker than that between the laurylamine and albite/quartz sufaces， which confirms the flotation results of the minerals. The IR spectrum analysis shows that hydrogen bond and electrostatic adsorptions occur between the laurylamine and the diatomite， albite and quartz surfaces in a slurry of pH 55. However， these actions between the laurylamine and the diatomite surfaces are weaker than those between the laurylamine and albite/quartz sufaces， resulting in its bad floatability. References | Related Articles | Metrics

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Critical Corrosion Rate Model for Reinforcement During Cracking of Concrete Cover QIU Zhaoguo， LIANG Li， ZHANG Fengpeng 2014, 35 (2):  290-293.  DOI: 10.12068/j.issn.1005-3026.2014.02.031 Abstract ( 572 )   HTML   PDF (623KB) ( 720 )   Based on the theory of elasticity and Bazant’s physical model， the loop stress in concrete cover was modified correspondingly by introducing the concept of tensile damage， and models of critical corrosionexpansion stress and reinforcement corrosion rate were built at the moment when the concrete cover began to crack. By considering the filling effect of corrosion products in clearance between reinforcement and concrete and in the cracks， focus was given on the influences of the reinforcement diameter， concrete cover thickness and corrosionexpansion coefficient on the critical corrosion rates under 3 different loop stress conditions. These 3 conditions are proposed as perfect elasticity， Bazant model and tensile damage hoop stress， respectively. The results show that the critical corrosion rate decreases with the increase of the bar diameter， and increases with the increase of concrete cover thickness and corrosionexpansion coefficient. The critical corrosion rate in perfect elasticity is higher than that in Bazant model and in tensile damage. Finally， by comparing with Morinaga’s models， the models introduced in this paper are proved to be reasonable. References | Related Articles | Metrics

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Partitioning Method of Dominant Groups Based on Characteristics of Structural Plane GUO Mudan， ZHU Fusheng， WANG Shuhong， RONG Xiaoyang 2014, 35 (2):  295-298.  DOI: 10.12068/j.issn.1005-3026.2014.02.032 Abstract ( 711 )   HTML   PDF (305KB) ( 554 )   The past partitioning methods of dominant groups are all based on the orientation information of structural planes， and they do not consider the effect of mechanical characteristics of structural planes and partitioning indexes on dominant groups partitioning， which may lead to the wrong partitioning results. In this respect， the mechanical characteristics quantified by CSPC(a classification method of structural plane character) were introduced for partitioning the dominant groups based on the characteristics of structural planes， and the partition of dominant groups was achieved by an iterative variable fuzzy model. It was concluded that the influence of mechanical characteristics on dominant groups partitioning can not be ignored. Shear strength parameters can be forecast by the partitioning method of dominant groups based on the characteristics of structural planes， which may lay the basis for the subsequent block stability analysis. References | Related Articles | Metrics

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Seismic Wave Propagation Around Circular Tunnel Structure in Semiinfinite Soil Body YANG Xujiao， HU Zhendong， LIANG Jun， JIA Hongrui 2014, 35 (2):  299-304.  DOI: 10.12068/j.issn.1005-3026.2014.02.033 Abstract ( 756 )   HTML   PDF (1014KB) ( 625 )   Based on the scattering theory of elastic waves， the scattering of SH wave and the dynamic stress concentration around circular tunnel with lining were investigated by employing the wave function expansion and mirror methods. The analytical solution of the problem， which was taken as a group of unlimited algebraic equations， was derived， and the numerical solution of the dynamic stress concentration factor around the lining was given. The effects of the shear elasticity of the surrounding rock and the lining， together with the wave number on the dynamic stress concentration factors were analyzed. It is shown that the shear elasticity of the surrounding rock and the wave number are factors that influence dynamic stress concentration， which may provide important theoretical basis for the earthquake evaluation of lining. References | Related Articles | Metrics

Mechanical Engineering

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Grinding Contact Area and Grinding Force Modeling Based on Impact Principle XIU Shichao， LIU Minghe， ZHANG Xiuming， BAI Bin 2014, 35 (2):  268-271.  DOI: 10.12068/j.issn.1005-3026.2014.02.026 Abstract ( 591 )   HTML   PDF (409KB) ( 497 )   In a grinding process， the grinding force is generated from the joint actions of sliding friction， plough and cutting. The calculated grinding force which only takes account of the cutting process has big error， compared with the measured values. Based on the shock effect in the grinding contact area on the grinding process， the contact area was divided into impact area and cutting area. Changes in the impact load from the grits on a workpiece in the impact zone were analyzed to model the impact load generated from single grit， as well as modeling the number of grits involved in the impact. Moreover， the theoretical calculation models of grinding force and total grinding force were also developed. Experimental study verified the correctness of the theoretical analysis. References | Related Articles | Metrics