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15 July 2018, Volume 39 Issue 7 Previous Issue    Next Issue
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Information & Control

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Particle Swarm Optimization Localization Algorithm Based on Sample Mean and Median HUANG Yue-yang， JING Yuan-wei， ZHANG Si-ying， SHI Yuan-bo 2018, 39 (7):  913-917.  DOI: 10.12068/j.issn.1005-3026.2018.07.001 Abstract ( 583 )   HTML   PDF (526KB) ( 541 )   The non-line-of-sight(NLOS)state was determined by the method of hypothesis testing for indoor line-of-sight/non-line-of-sight (LOS/NLOS) hybrid environment. And particle swarm optimization algorithm with shrinkage factor was used to locate. When the sampling value was abnormal， the performance of sample median was better than sample mean. Minimum square error cost functions of the sample mean and sample median were established in LOS and NLOS state. In order to enhance the global and local search ability of the algorithm， the shrinkage factor was introduced on the basis of particle swarm optimization algorithm. Simulation results show that the improved particle swarm optimization algorithm based on sample mean and median (IPSOSMM)has higher localization accuracy than that of the improved particle swarm optimization algorithm based on sample mean (IPSOSM)and the general particle swarm optimization algorithm when the NLOS block is serious. References | Related Articles | Metrics

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Optical Fiber Gas Sensor Based on Graphene and Intermodal Interference ZHAO Yong， ZHANG Shu-yuan， WEN Gao-feng， HAN Zi-xiong 2018, 39 (7):  918-921.  DOI: 10.12068/j.issn.1005-3026.2018.07.002 Abstract ( 703 )   HTML   PDF (601KB) ( 732 )   In order to precisely monitor and forecast noxious and harmful gases in the air， an optical fiber gas sensor was proposed including a section of tapered and dislocated optical fiber， and the tapered region was coated with graphene. The tapered fiber sensing area which was wrapped with graphene and intermodal interference caused by the dislocation of fiber would substantially increase evanescent field， which transmitted along the surface of fiber， and would have a significant sensitizing effect on the gas sensing of the optical waveguide. At the same time， the gas molecules adsorbed on the surface of graphene would lead to change of the effective refractive index of the composite waveguide， resulting in the corresponding wavelength drift and attenuation. By detecting the change of the output optical signal， the concentration of gas molecules could be detected. Based on this principle， the sensor realized a gas sensitivity of 1.2×104nm. The research shows that the sensing structure has the advantages of small volume， good mechanical strength， good spectral quality and high sensitivity etc. References | Related Articles | Metrics

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Robust Exponential Control for a Class of Switched Singular Time-Delay Systems YANG Dong-mei， YAO Qi 2018, 39 (7):  922-926.  DOI: 10.12068/j.issn.1005-3026.2018.07.003 Abstract ( 559 )   HTML   PDF (324KB) ( 489 )   The robust exponential admissibility problems and robust exponential stability control problems of uncertain switched singular time-varying delay systems were studied. By way of free-weighting matrices and average dwell time methods， the sufficient condition of exponential admissibility of uncertain switched singular time-delay systems was given. Then on the basis of linear matrix inequality (LMI) approach and the singular system Lyapunov stability theory， a state feedback controller with memory was designed， resulting in the regular， impulse free， and exponentially stable closed-loop systems. Finally， the feasibility and validity of the proposed method were finally demonstrated by illustrative example. References | Related Articles | Metrics

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Amplitude and Phase Estimation Beamforming Algorithm Combined with Subspace Projection SHE Li-huang， YAN Xin， ZHANG Shi 2018, 39 (7):  927-930.  DOI: 10.12068/j.issn.1005-3026.2018.07.004 Abstract ( 634 )   HTML   PDF (662KB) ( 666 )   In medical ultrasound imaging， amplitude and phase estimation (APES) beamforming algorithm makes the amplitude estimation of the desired signal more robustly， but it is at the expense of resolution. To solve this problem， the adaptive beamforming algorithm was proposed which was based on APES and was combined with subspace projection. Firstly， the weighted vector was calculated by the amplitude phase estimation algorithm， and then the weighted vector was projected to the desired signal subspace of the echo signal to suppress the noise and interference， and to improve the resolution and contrast of the image. The simulation results show that the proposed algorithm is superior to the original amplitude and phase estimation algorithm in terms of resolution， contrast and robustness. References | Related Articles | Metrics

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Research on Modeling of Hybrid Game System for Missile Interception HAO Li-na， CAO Rui-min， WANG Feng-li， BAI Guo-li 2018, 39 (7):  931-936.  DOI: 10.12068/j.issn.1005-3026.2018.07.005 Abstract ( 714 )   HTML   PDF (588KB) ( 942 )   In the missile defense system， there is not only the continuously evolving of trajectories， but also the decision of the event strategy. The differential game and the event game cannot effectively describe the hybrid characteristics alone. Therefore， the missile defense system was regarded as a kind of hybrid system， and hybrid game modeling method of missile interception process (MIP) was proposed. Then the event game model of missile interception was established based on the HSTPN (hybrid stochastic timed Petri net)， and the differential game model of the missile interception process was established based on the dynamic model of the missile. Taking the “Minuteman Ⅲ”as the example， the hybrid process was simulated with some practical cases. It was turned out to be that the hybrid interception description scheme based on hybrid games can describe not only the continuous trajectories of missile， but also selection of strategy. References | Related Articles | Metrics

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An Innovative Method for Fingertip and Finger Pointing Detection Based on Contour Features DAI Yuan-xing， YU Tian-biao， YANG Jian-yu， WANG Wan-shan 2018, 39 (7):  937-941.  DOI: 10.12068/j.issn.1005-3026.2018.07.006 Abstract ( 650 )   HTML   PDF (595KB) ( 1507 )   K-Curvature and convex hull theory based finger detecting algorithm always suffering inaccurate fingertip capture. A new fingertip and finger pointing detection method was proposed which was based on finger contour features. There were three key steps in the method: contour smoothing， linear region detection， and fingers pointing and tips detection. Accurate and fast fingertip recognition processing could be realized. The proposed algorithm runs fast and accurately in fingertip recognition process. Through the experimental verification of different gestures， the fingertips position could be accurately located and the fingers pointing information could be obtained by the proposed algorithm. It can also meet the real-time requirements in this type of human-computer interaction system， and has strong adaptability to different finger direction. References | Related Articles | Metrics

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Method of Measuring the Benign and Malignancy of Pulmonary Nodules Based on ARG ZHAO Hai， YANG Ting-ting， ZHU Hong-bo， DOU Sheng-chang 2018, 39 (7):  942-948.  DOI: 10.12068/j.issn.1005-3026.2018.07.007 Abstract ( 575 )   HTML   PDF (772KB) ( 699 )   Identification of benign and malignant pulmonary nodules is an important task during the diagnosis of lung cancer. Aimed for solving this problem， a method of measuring the malignancy of pulmonary nodules based on the attributed relational graph (ARG) was proposed. Feature structures of input lung nodule CT image patches were constructed with ARGs and the nodule category template was built by mining and-or graph (AoG) from ARGs in the proposed method. Moreover， Markov blanket discovering algorithm was applied for discriminative features selection to reduce the node number of ARGs， so the computational complexity of the graph matching for AoG mining was greatly reduced. Experimental results show that the recognition rate of malignant pulmonary nodules is up to 90.12%， thus the proposed method can help identify the benign and malignant pulmonary nodules accurately and rapidly. References | Related Articles | Metrics

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An Algorithm for Predicting Nodes Movement Based on Markov Chain in MWSN ZHU Jian， LI Jia-zheng 2018, 39 (7):  949-953.  DOI: 10.12068/j.issn.1005-3026.2018.07.008 Abstract ( 549 )   HTML   PDF (600KB) ( 758 )   In existing MWSN(mobile wireless sensor network)， the problem of hot spot allocation was not solved well， and the utilization rate of network was low. It is possible to optimize the network structure by predicting the trajectory of mobile nodes. A trajectory prediction algorithm named MTPA combined with acceleration was proposed. Firstly， modeling the motion state of the node was established. Secondly， a step motion state probability transfer matrix was done. Finally， Markov chain based multi-step probabilistic transfer matrix algorithm was presented. In order to verify the performance of the algorithm， experiments were carried out on the STM32F407 platform， the experimental results show that comparing with traditional uniform prediction algorithms and frequency statistics algorithms， the prediction accuracy of MTPA has certain advantages， and relevant research results can be used in MWSN. References | Related Articles | Metrics

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Exponential Stability of Single-Module Repairable System with Warning State LIU Dong-xu， WANG Lan-hao， JIA Yao， ZHANG Jing-wen 2018, 39 (7):  954-958.  DOI: 10.12068/j.issn.1005-3026.2018.07.009 Abstract ( 583 )   HTML   PDF (367KB) ( 537 )   A kind of single-module repairable system with warning state was investigated， which can be expressed as a set of differential equations. By selecting the appropriate state space and the definition domain of the system operator， the equations were transformed into an abstract Cauchy problem in a Banach space. With the functional analysis method and linear operator semigroup theory， the eigenvalue 0 was proved to be the strictly dominant simple eigenvalue of the system. It shows the solution of the system is asymptotically stable. Then by studying the spectrum distribution of the main operator of the system， it was proved that the essential spectrum bound of the main operator of the system is negative. Finally， the variation of essential spectrum bound of the main operator under compact perturbation were discussed. The results demonstrate that the dynamic solution of the system is exponentially stable. References | Related Articles | Metrics

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A String Collection Indexing Method with String Length and Position Constraint YU Chang-yong， GAO Ming， BAI Lu-yi， ZHAO Yu-hai 2018, 39 (7):  959-963.  DOI: 10.12068/j.issn.1005-3026.2018.07.010 Abstract ( 640 )   HTML   PDF (383KB) ( 545 )   An index method of string collection was proposed based on BWT (Burrows-wheeler-transform) for solving the exact substring queries with string length and matching position constraints. Firstly， the BWT and exact string query based on it were discussed. Then the impact of string collection， string length and substring position upon the original BWT index was analyzed. Finally， the fast calculation problem was discussed and solved from the position of the matching suffix to the string ID and position on the string of the matching substring. The approximate string matching was conducted on three real string collections and compared the results of index method proposed and the original one. The experimental results showed that the method proposed based on BWT speeded up the process of exact substring queries with string length and matching position constraints considerably in the case of keeping the index size. Therefore， the proposed method was suitable for indexing large-scale string collection for string similarity match and joint. References | Related Articles | Metrics

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Total Variation Regularization CT Iterative Reconstruction Algorithm Based on Augmented Lagrangian Method XIAO Da-yu， GUO Yang， LI Jian-hua， KANG Yan 2018, 39 (7):  964-969.  DOI: 10.12068/j.issn.1005-3026.2018.07.011 Abstract ( 988 )   HTML   PDF (1046KB) ( 796 )   A novel algorithm based on augmented Lagrangian method was presented to solve total variation regularization problem (ALMTVR) of the CT iterative reconstruction. The classical algebraic reconstruction technique (ART) was compared with the ALMTVR algorithm， the simulation data and actual data are used in the experiment. The ALMTVR algorithm and the ART algorithm were used to reconstruct the images respectively， and the reconstruction images were compared and analyzed. Results showed that， compared with ART algorithm， the proposed algorithm can significantly improve image quality and reconstruction speed， which indicates the proposed algorithm is effective and has potential applications in the CT imaging system. References | Related Articles | Metrics

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Prediction of Wine Alcohol Concentration Based on Sample Selection and PSO-ANN WANG Qiao-yun， ZHENG Nian-zu 2018, 39 (7):  970-975.  DOI: 10.12068/j.issn.1005-3026.2018.07.012 Abstract ( 757 )   HTML   PDF (990KB) ( 653 )   In order to improve the accuracy and robustness of the quantitative analysis model， a new sample selection algorithm named KM was proposed. In the experiment， 40 samples of wine were used as the analysis objects， and the KM algorithms was compared with traditional sample selection algorithms， such as RS， KS and SPXY. The experimental results show that |RMSEP-RMSEC| obtained by KM algorithm is superior to the other three algorithms， and there are significant differences in RPD， which indicates that KM method has good prediction accuracy. In order to overcome the neural network training algorithms drawbacks that BP neural networks converge slowly and is easy to fall into local optimum， the particle swarm optimization algorithm was used to optimize the parameters of artificial neural network (PSO-ANN). The results show that PSO-ANN algorithm can improve the convergence velocity of training， robustness and the accuracy of classification than genetic algorithm， artificial fish swarm algorithm， and shuffled frog-leaping algorithm. References | Related Articles | Metrics

Materials & Metallurgy

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Corrosion Resistance and Cytotoxicity of Medical Degradable Mg-3Zn-0.5Sr Alloy ZHANG Ya-jing， GUO Ting-ting， LI Shuai-ping， PENG Wu-xian 2018, 39 (7):  976-980.  DOI: 10.12068/j.issn.1005-3026.2018.07.013 Abstract ( 587 )   HTML   PDF (1003KB) ( 514 )   The hydroxyapatite (HA) coating was prepared on the surface of Mg-3Zn-0.5Sr alloy by bionic method. The morphology and structure of the coating were characterized by SEM， EDS and XRD. Electrochemical and immersion corrosion experiments were carried out to study the degradation of the alloy and cytotoxicity experiments were also subjected to the HA-coated and uncoated Mg alloy samples. The results show that a dense HA layer with the thickness of 30~40μm can be deposited on the surface of the Mg-3Zn-0.5Sr alloy， which can effectively reduce the degradation rate of this alloy. Relative viability of cells is more than 100% and all samples have cytotoxicity scores of 0， after the cells are cultured in the extracts with the volume fraction of 25% for 4 days. References | Related Articles | Metrics

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Influence of Negative Bias Voltage on Microstructure and Properties of CrAlN Coatings by Arc Ion Plating LIN Zeng， CHEN Bin， QIAO Hong， ZHAO Xiao-bo 2018, 39 (7):  981-985.  DOI: 10.12068/j.issn.1005-3026.2018.07.014 Abstract ( 649 )   HTML   PDF (905KB) ( 684 )   Using arc ion plating， CrAlN coatings were deposited on high speed steels. The effects of the negative bias voltage on microstructure and properties of the CrAlN coatings were investigated through analyzing surface morphologies， microstructure， microhardness， adhesion strength and tribological properties. The results showed that with the increase of the negative bias voltage， the surface macroparticles reduced gradually and the coating became denser. However， further increasing the negative bias voltage over -200V， the ion bombarding was so strong that many defects reappeared on the coating surface. Therefore， the grain size reached a minimum value and the coating was well crystallized at the bias voltage of -200V. Moreover， it was found that the microhardness and adhesion strength firstly increased and then decreased with the increase of the negative bias voltage. When the voltage was -200V， the microhardness reached the maximum value of 28.6GPa and the coating performed the best tribological properties. References | Related Articles | Metrics

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Influence of Thermal Reserve Zone Temperature in Blast Furnace on Gas Utilization Rate MENG Fan-chao， ZOU Zong-shu 2018, 39 (7):  985-989.  DOI: 10.12068/j.issn.1005-3026.2018.07.015 Abstract ( 776 )   HTML   PDF (393KB) ( 928 )   The relationship between temperature of thermal reserve zone and the gas utilization rate of blast furnace was investigated. Considering thermodynamics and practical condition， only the reduction of ferrous oxide occurs in the thermal reserve zone. Thus， the thermodynamic analysis and kinetic analysis of reduction reactions in thermal reserve zone were carried out with standard Gibbs free energy calculation and unreacted shrinking core model， respectively. The results of thermodynamic analysis show that only when the (H2+H2O) volume fraction is smaller than 0.3， lowering temperature is effective for improving gas utilization. The kinetic analysis shows that decreasing temperature from 1273K to 1223K， the reduction rate with H2 decreases more than that with CO， showing that the influence of temperature on the reduction with H2 is greater than that with CO. For most blast furnaces， the required reduction time is somewhat longer than the burden residence time in the thermal reserve zone， which means that the reduction reactions in thermal reserve zone don’t attain their equilibria， and lowering temperature is not effective for improving gas utilization. References | Related Articles | Metrics

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Effect of MgO and Nut Coke Mixed Charging on the Melting Properties of Sinter GUO He， SHEN Feng-man， ZHANG Li， JIANG Xin 2018, 39 (7):  990-994.  DOI: 10.12068/j.issn.1005-3026.2018.07.016 Abstract ( 738 )   HTML   PDF (552KB) ( 561 )   Using sinters with different MgO contents as raw material， the effects of MgO content and nut coke mixed charging on the melting temperature， melting zone and maximum pressure drop of sinter bed were investigated， and the change of melting temperature was analyzed. The experimental results show that， when MgO mass fraction in sinter increases from 1.3% to 2.0%， the starting melting temperature (t○S) changes slightly， the dripping temperature (t○D) increases， the melting zone (t○D-t○S) increases from 156℃ to 207℃， and the maximum pressure drop increases from 10kPa to 11kPa. When sinter with w(MgO)=2.0% is mixed with nut coke， t○S increases from 1312℃ to 1324℃， t○D decreases from 1519℃ to 1480℃， melting zone (t○D-t○S) decreases from 207℃ to 156℃， and the maximum pressure drop decreases from 11kPa to 7kPa， showing that the mixed charging of sinter with nut coke can improve the melting-dripping property of burden. References | Related Articles | Metrics

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Study on Evolution of Phase Precipitation in High Aluminum Slags LI Qiang， PAN Tao， ZHANG Han-yang， DING Hao 2018, 39 (7):  995-999.  DOI: 10.12068/j.issn.1005-3026.2018.07.017 Abstract ( 599 )   HTML   PDF (1074KB) ( 591 )   To improve the leaching performance of high alumina slags， DSC and SEM-EDS analyses were employed to study the phase precipitation behaviors of high alumina slags during solidification with controlled cooling rates. The effects of cooling rate，n(CaO)/n(Al2O3) and MgO content on the evolution of phase precipitation were discussed. The results show that when the cooling rate increases， the solidification process tends to have severer segregation， the C2S phase transformation becomes more insufficient and the particle turns obviously coarse， so that the self-pulverization and leaching performance deteriorate. With the increase of n(CaO)/n(Al2O3) in the slags， the precipitation temperature of C12A7 rises and the activities of precipitation phases increase gradually as CA→C12A7→C3A. When the slags contains MgO， the phase of C2MS2 appears， which is detrimental to the phase transition of C2S. More importantly， MgO enriching in aluminum-bearing phase leads to the formation of Q phase， which deteriorates greatly the leaching and recovery rate of alumina. References | Related Articles | Metrics

Mechanical Engineering

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Effects of Specimen Shapes on the Friction Hydro-Pillar Processing Forming of Aluminum Alloys REN Zhao-hui， JU Jian-zhong， LYU Dong-jie， XU Yu-hang 2018, 39 (7):  1000-1004.  DOI: 10.12068/j.issn.1005-3026.2018.07.018 Abstract ( 564 )   HTML   PDF (1278KB) ( 686 )   In order to study the effects of different specimen shapes on the friction hydro-pillar processing (FHPP) forming of aluminum alloys， 7075 aluminum alloy was selected as the experimental object， and the ABAQUS finite element software was used. The numerical simulation of the complex thermo-mechanical coupling process of FHPP was simplified to a two-dimensional axisymmetric model and analyzed with FRIC subroutine and grid remeshing technique. By comparing the temperature cloud， deformation and stress distribution， the results showed that the shape of the specimen can affect the forming of welding defects and the defect size， the shape of the welding hole has a greater impact on the welding defect than the shape of welding rod and the fillet can be very good to prevent the forming of welding defects， the rectangular weld hole has the largest effect on hindering the fluidity for plastic metals， the chamfer weld hole has a second influence， and the fillet weld hole has the least influence which leads to better welding quality. References | Related Articles | Metrics

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Experimental Study on the Wire Electrical Discharge Machining of Rotary Parts Based on the Response Surface Method GONG Ya-dong， MA Xiao-teng， SUN Yao 2018, 39 (7):  1005-1010.  DOI: 10.12068/j.issn.1005-3026.2018.07.019 Abstract ( 572 )   HTML   PDF (1527KB) ( 724 )   The low speed wire electrical discharge machining (LS-WEDM ) method was used to fabricate the rotary CuW70 workpiece. Box-Behnken experiment of CuW70 was designed with Design-Expert software， and the response surface method was used to analyze the influencing rule of different speed parameters on surface roughness and material removal rate. Then the optimized machining parameters for high machining efficiency and precision were obtained. The results showed that the influencing order of speed parameters on the surface roughness is followed by rotating speed， feeding speed and wire speed. And the influencing order of speed parameters on material removal rate is followed by feeding speed， rotating speed and wire speed. The multi-objective optimizing results indicated that when the rotating speed is 46r/min， the feeding speed is 1.0mm/min， and the wire speed is 45mm/s， the surface roughness is 0.882μm and the material removal rate is 0.625mm3/min. References | Related Articles | Metrics

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Numerical Investigation of Adjustable Inlet Guide Vane with Trailing Edge′s Self-Induced Blowing in Compressors XIN Jian-chi， WANG Xiao-fang， ZHOU Lu-sheng， YANG Shu-hua 2018, 39 (7):  1011-1016.  DOI: 10.12068/j.issn.1005-3026.2018.07.020 Abstract ( 666 )   HTML   PDF (1867KB) ( 673 )   A self-induced structure was designed for the trailing edge of the guide vane of a centrifugal compressor to reduce the impact of rotor-stator interaction and the aerodynamic load on the following impeller， which improved the safety of the impeller. Through the effect of pressure differences， the structure of the trailing edge of the guide vane regulated the flow phenomenon and the partial wake of the guide vane was compensated. Based on the numerical simulation， a centrifugal compressor with adjustable inlet guide vane was used as an example. The results showed that the self-induced flow in the guide vane is not remarkable at the 0 degree guide vane angle. With the increase of the guide vane angle， the wall separation flow and the pressure differences on the guide vane are increased， and the internal self-induced flow is strengthened. With small increase of wake intensity near the root， the wakes distribution at the middle and top is improved， i.e. the pure wake reduces to a weak wake， which further decreases the aerodynamic load on the impeller. Meanwhile， without any injection air， the self-induced structure has little influence on the compressor performance. References | Related Articles | Metrics

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Finite Element Model Updating of Tower Cranes Based on the Non-dominated Sorting Genetic Algorithm QIN Xian-rong， ZHANG Qing， LIU Chao， XU Jian 2018, 39 (7):  1017-1021.  DOI: 10.12068/j.issn.1005-3026.2018.07.021 Abstract ( 593 )   HTML   PDF (1150KB) ( 683 )   A finite element model updating method based on the non-dominated sorting genetic algorithm Ⅱ (NSGA-Ⅱ) was proposed， which ensures that the established finite element model can accurately reflect the actual state of the structure. Firstly， the finite element model was established， and the effective response surface substitution model was obtained based on the quadratic polynomial response surface method. Then the response surface model was updated with NSGA-Ⅱ. Finally a reliable finite element model was obtained which can satisfy the requirements of engineering precision. An engineering example of a tower crane’s finite element model updating was provided. In accordance with the measured data， the results indicated that the multi-objective optimization algorithm based on NSGA-Ⅱ has an ideal effect for the finite element model updating， and the updated finite element model can accurately reflect the mechanical properties of the structure. References | Related Articles | Metrics

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Life Calculation of TBM Main Bearing Based on Load Distribution and Statistics ZHANG Chun-guang， QU Fu-zheng， NING Shi-zhe， XIE Zheng-yi 2018, 39 (7):  1022-1027.  DOI: 10.12068/j.issn.1005-3026.2018.07.022 Abstract ( 649 )   HTML   PDF (1316KB) ( 721 )   With the stiffness characteristics and boundary conditions considered， L-P theory and slicing method were introduced to calculate the rated life of the main bearing in the tunnel boring machine (TBM) used in the second section of the diversion project’s main line for the central region of Jilin province. The statistical analysis of TBM thrust force record was carried out to calculate the life of the main bearing based on Miner’s cumulative damage theory. The results showed that the internal load distribution of the main bearing is greatly affected by the stiffness characteristics of the connection structures， and the slicing method is suitable well for calculating the main bearing’s rated life. With the modified size and form of the connection structure， the uniformity of raceway load distribution is improved greatly and the main bearing’s rated life is extended. In statistics， the TBM thrust forces are truncated normal distribution approximately， and the service life of the main bearing could be calculated based on the rated thrust force. References | Related Articles | Metrics

Resources & Civil Engineering

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RFPA3D Modeling and Application for Complex Rock Masses Based on SURPAC HU Ying-peng， REN Feng-yu， DING Hang-xing， FU Yu 2018, 39 (7):  1028-1032.  DOI: 10.12068/j.issn.1005-3026.2018.07.023 Abstract ( 791 )   HTML   PDF (3689KB) ( 663 )   Pre-processing function for RFPA3D is not so strong that rock mass model with complex geomorphology could not be effectively and conveniently built. While SURPAC， a professional mining software， has a strong ability in modeling complex geological body. Besides， the requirement of unit types for both two softwares is hexahedral. On this basis， a method to build the model in RFPA3D from SURPAC was proposed. According to the data relationship between the two softwares， a conversion program named STOR.m was developed in MATLAB to achieve the model conversion from SURPAC to RFPA3D. The program was used in a slope instability analysis model in an open pit iron mine. Results show that the model conversion method can be applied conveniently and extends the application of SURPAC and RFPA3D. References | Related Articles | Metrics

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Healing Experiment for Rock Mass Structural Plane Based on Bacterially Induced Calcium Carbonate LIU Dong， SHAO An-lin， ZHAO Xin， JIN Chang-yu 2018, 39 (7):  1033-1037.  DOI: 10.12068/j.issn.1005-3026.2018.07.024 Abstract ( 622 )   HTML   PDF (1311KB) ( 1032 )   Sporosarcina pasteurii-induced calcium carbonate precipitation was used to heal structural planes of migmatitic granite. Conductivity variations was applied to characterize the urease activity for bacteria liquid to investigate the growth law and physicochemical properties of Sporosarcina pasteurii after curing in activated culture. Additionally， microscopic methods including XRD， EDS and SEM were conducted to analyze the induced products of Sporosarcina pasteurii on structural planes. The results show that， the urease activity for bacteria liquid of Sporosarcina pasteurii is the highest after curing 22 ~ 28 hours. The optimum physicochemical environment for Sporosarcina pasteurii growth is 30℃ at pH 8. The sediment product produced by Sporosarcina pasteurii on structural planes is cubic crystals with a side length of 5~10μm， and they grow in a way of screw dislocation to backfill and then repair structures planes. References | Related Articles | Metrics

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Analysis of Pre-existing Crack Propagation Process Based on Discrete Element Method ZHAO Yong， YANG Tian-hong， YU Qing-lei， ZHANG Peng-hai 2018, 39 (7):  1038-1043.  DOI: 10.12068/j.issn.1005-3026.2018.07.025 Abstract ( 686 )   HTML   PDF (982KB) ( 642 )   Uniaxial compression experiments were carried out for granite specimen with pre-existing cracks. Variation laws of rock strength and elastic modulus under different crack angles were obtained， and the crack propagation process was recorded. The calculation model for rock particle flow under different flaw inclinations was established and the micro-parameters of calculation model were calibrated based on the laboratory testing results. Crack information during the crack propagation process was extracted by FISH language and was also analyzed in detail. The results show that with the increase of crack inclination， both the crack initiation stress and initiation angle increase continuously. The crack propagation types change from wing-crack-dominated to secondary-crack-dominated. Through the analysis of crack aggregation coefficient， it is found that with the increase of crack angle， the curve of crack aggregation coefficient changes from smooth to tortuous， and the crack propagation path is under the transition from concentrated to decentralized. References | Related Articles | Metrics

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Dynamic Optimization of the Staging Scheme of Open-Pit Metal Mines in Different Market Conditions WANG Qing， TIAN Wei-xi， GU Xiao-wei， QIN Zong-chen 2018, 39 (7):  1044-1048.  DOI: 10.12068/j.issn.1005-3026.2018.07.026 Abstract ( 597 )   HTML   PDF (349KB) ( 502 )   Based on the theory of floating cone exclusive and dynamic programming method， dynamic optimization of the staging scheme was used in open-pit mines. The optimal installment scheme could be obtained under the conditions of the different iron ore market by using 20 million tons of ore quantity as boundary increment to produce a series of geological optimal candidate boundaries by using cone elimination， and dynamic programming for the maximum of the net present value. The results showed that when the average price growth rate are 1.5%，3% and 4.5%， and the corresponding annual growth rate of production costs are 0.5%， 1% and 2%， the best scheme is divided into two stages and three stages. The economic net present value of the two stages of mining scheme is 1.2%， 3% and 4.3% more than that of the three stage mining scheme， but the amount of ore is 9.2%， 7.9%， and 13.1% less than that of three stage mining scheme. It can be seen that the net present value or the amount of mineral resources has a very important influence on the selection of the optimal scheme. References | Related Articles | Metrics

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Risk Analysis of Rail Haulage Accident Based on Composite Model XU Qing-wei， XU Kai-li 2018, 39 (7):  1048-1052.  DOI: 10.12068/j.issn.1005-3026.2018.07.027 Abstract ( 603 )   HTML   PDF (810KB) ( 648 )   A composite risk analysis model was put forward to analyze the rail haulage accident in inclined tunnel systematically. The model combines preliminary hazard analysis-layer of protection analysis (PHA-LOPA) with bow-tie analysis together based on Bayesian network. First， taking advantage of two-way reasoning ability of Bayesian network identified the risk Bayesian accident nodes with the help of GeNIe software. Second， the accident nodes was studied using PHA-LOPA to determine the causes and results of the accident， and to set independent protection layer to reduce the risk level of the accident nodes. Third， bow-tie analysis was performed on the accident node where the residual risk level was still high， safety barriers were set and the occurrence of the accident was further controlled. The proposed composite risk analysis model was applied to a rail haulage accident in inclined tunnel in a mine， and the validity and feasibility was verified by the results. References | Related Articles | Metrics

Management Science

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Executive Power， Heterogeneity of Institutional Investors and the Speed of Capital Structure Adjustment HOU Li， ZHONG Tian-li， ZHANG Tian-yu 2018, 39 (7):  1053-1058.  DOI: 10.12068/j.issn.1005-3026.2018.07.028 Abstract ( 542 )   HTML   PDF (392KB) ( 645 )   The fixed effect model based on the data of China’s A-share listed companies in 2000~2015 was used to analyze the effect of executive power on the speed of capital structure adjustment. Then the effect of institutional investors’ holding and its heterogeneity on the relationship between executive power and the speed of capital structure adjustment was further investigated. The results showed that the more powerful an executive has， the lower the speed of capital structure adjustment would be. After distinguishing different debt levels， the negative relationship between executive power and the speed of capital structure adjustment exists only when the actual captical structure is lower than the target level. On the whole， institutional investors’ holding has no significant influence on the relationship between executive power and the speed of capital structure adjustment. However， stable institutional investors’ holding can weaken the negative correlation between executive power and the speed of capital structure adjustment with respect to short-termism institutional investors. It contributes to the restraint of executive power and optimizes the decision making of capital structure. References | Related Articles | Metrics

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Evaluation and Construction of the Governance Capacity of the Supervisory Board of Mixed Ownership Enterprises YANG Kai， ZHAO Xi-nan 2018, 39 (7):  1059-1064.  DOI: 10.12068/j.issn.1005-3026.2018.07.029 Abstract ( 544 )   HTML   PDF (384KB) ( 506 )   The complementarity of the individual advantages of the governance capacity of the supervisory board is a necessary condition for the development of mixed ownership economy. It is an important basis to judge the individual advantages of the governance capacity. Based on the idea of competitive superiority， the value parameter was determined from the most favorable perspective of the enterprise being evaluated， and the individual advantage discriminant model and the democratic discriminant model of the supervisory board’s governance capacity of mixed enterprises were put forward. At the same time， the model solution was given. A total of 10 mixed ownership enterprises in China were used as the research samples， and based on the evaluation method of the supervisory board’s governance capacity using individual advantages， a calculation example was analyzed and the countermeasures were raised for scientific evaluation. References | Related Articles | Metrics