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15 October 2019, Volume 40 Issue 10 Previous Issue    Next Issue
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Information & Control

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Clustering Optimization of Sensitivity Matrix in MIT WANG Xu， ZHANG Xin-hui， YANG Dan 2019, 40 (10):  1369-1375.  DOI: 10.12068/j.issn.1005-3026.2019.10.001 Abstract ( 671 )   HTML   PDF (883KB) ( 884 )   Aiming at the geometric difference of sensitivity matrix， a clustering-based method for optimizing sensitivity matrix was proposed. Firstly， the influence of geometrical difference of sensitivity matrix on MIT image quality was analyzed. Then， based on the geometric difference， the vector of the sensitivity matrix was clustered， and the energy function was applied to assign different weights to the grouped sensitivity vector， and a clustering optimization sensitivity matrix was constructed. Finally， the optimized sensitivity matrix was used to reconstruct the MIT image with the linear back projection algorithm and the Newton-Raphson(NR) iterative algorithm. Experimental results showed that with the sensitivity matrix of clustering optimization， the mean square error of the linear back projection algorithm is reduced by more than 26%， the image correlation coefficient is increased by more than 10%， the mean square error of NR iterative algorithm is decreased by more than 5%， and the correlation coefficient is increased by more than 4%， which proves the effectiveness of the proposed method. References | Related Articles | Metrics

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Vehicle Face Recognition Algorithm Based on Weighted and Sparse Nonnegative Matrix Factorization SHI Chun-he， WU Cheng-dong 2019, 40 (10):  1376-1381.  DOI: 10.12068/j.issn.1005-3026.2019.10.002 Abstract ( 583 )   HTML   PDF (556KB) ( 812 )   In order to improve the vehicle face recognition accuracy in traffic videos under various illumination conditions， a vehicle face recognition algorithm based on improved nonnegative matrix factorization(NMF)was proposed. The vehicle face image and license plate information were acquired after image preprocessing. The original feature of vehicle face image was extracted adaptively based on the special illumination condition. For the importance variation of different pixels in vehicle face image， a feature dimension reduction based on weighted and sparse NMF(WSNMF)was established. The vehicle legality can be defined by determining the similarity of features and the consistency of license plates. The experimental results showed that the proposed algorithm has better recognition performance， and genuine acceptance rate(GAR)and false rejection rate(FRR)can reach 0.9875 and 0.04， respectively， and meet the real-time requirements. References | Related Articles | Metrics

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Location Algorithm of Wireless Sensor Network Nodes Based on Semi-definite Programming WU Gang， WU Cheng-dong 2019, 40 (10):  1381-1385.  DOI: 10.12068/j.issn.1005-3026.2019.10.003 Abstract ( 576 )   HTML   PDF (434KB) ( 632 )   Aiming at node localizations of wireless sensor network(WSN)， a semi-definite programming(SDP)optimization algorithm based on the maximum likelihood estimation(MLE)was proposed. Combining the effective anchor node position selection and ratio range setting， the SDP algorithm was used to relax the non-convex constraints， effectively reduce the impact of errors and get the actual position of measurement nodes. Changing the position of the anchor node can effectively solve the problem of inaccurate estimation of nodes outside the convex hull of the anchor node. The simulation results showed that the proposed SDP algorithm achieves high-precision in the position estimation of unknown nodes， and improves the convex optimization method. References | Related Articles | Metrics

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EEG-Based Feature Recognition of Stereoscopic Video Acceleration SHEN Li-li， GENG Xiao-quan， XU Li-sheng 2019, 40 (10):  1386-1391.  DOI: 10.12068/j.issn.1005-3026.2019.10.004 Abstract ( 565 )   HTML   PDF (714KB) ( 593 )   A PMEMD-2JSD-CSP model capable of adaptively extracting EEG features was established to clarify the separability of two classes uniform acceleration motion in deep of stereoscopic video. EEG signals were decomposed by the partial noise assisted multivariate empirical mode decomposition(PNA-MEMD)algorithm to obtain the intrinsic mode function(IMF)at each scale. An effective factor based on Jensen-Shannon distance(JSD)was used to select IMF adaptively from two different ranges， and the screening results were combined according to the weights to form a reconstructed signal. At last， the common spatial pattern(CSP)approach was applied to extract spatial features of the reconstructed signals， and the support vector machine(SVM)algorithm was employed to classify the spatial features. The best classification correct rate is 73.16%， which proves the validity of the feature extraction model for two classes of EEG signals. References | Related Articles | Metrics

Materials & Metallurgy

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Effect of Cooling Rate on Spheroidized Microstructure of GCr15 Bearing Steel HAN Dong-xu， DU Lin-xiu， WU Hong-yan， QI Min 2019, 40 (10):  1392-1397.  DOI: 10.12068/j.issn.1005-3026.2019.10.005 Abstract ( 622 )   HTML   PDF (3408KB) ( 844 )   The effect of cooling rate after a simulated hot-rolling process on the microstructures of network carbide precipitation and subsequent divorced eutectoid transformation in GCr15 bearing steel was investigated using electron probe and transmission electron microscopy. The results indicated that the rapid cooling treatment in the range of pre-eutectoid carbide formation temperature can inhibit the formation of network carbides and reduce the inter-lamellar spacing of flaky pearlite in the steel.When the cooling rate is 20℃/s， the spheroidizing annealing time can be reduced to about 2h in divorcing eutectoid treatment and the hardness of the tested sample reaches 1.95GPa.The results from selected-area electron diffraction show that the type of spheroidal carbide in the steel after spheroidization is M3C， which can not be changed by the regulation of cooling rate. References | Related Articles | Metrics

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Martensitic Transformation and Magnetic Properties of NiMnGaTi Ferromagnetic Shape Memory Alloy BAI Jing， YANG Zhen， ZHAO Chen-yu， ZHAO Xiang 2019, 40 (10):  1398-1402.  DOI: 10.12068/j.issn.1005-3026.2019.10.006 Abstract ( 650 )   HTML   PDF (2799KB) ( 662 )   The microstructure， martensitic transformation and magnetic properties of Ni53Mn23.5Ga23.5-○xTi○x○(x=0， 2， 5 and 8)ferromagnetic shape memory alloys were studied to investigate the effects of different preparation methods and different Ti contents on the martensitic transformation and magnetic properties. The results show that when the Ti content increases， the grain size becomes finer， the martensitic transformation temperatures and martensitic transformation decrease， and the precipitate density increases where the appropriate amount of second-phase precipitations can facilitate to improve the high brittleness of the alloy. The EDS analysis indicates that in Ti doping alloys， the second-phase precipitation is rich in Ni and Ti constituents. The Ti addition decreases the saturation magnetization dramatically. The saturation magnetizations of Ti0 and Ti2 melt spun ribbons at the rotation speed of 900r/min are almost the same as those of the as-cast samples. However， the saturation magnetizations of the Ti5 and Ti8 melt spun samples are obviously higher than those of the as-cast ones， because the non-magnetic second-phase precipitations are suppressed in the melt spun process. References | Related Articles | Metrics

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(Nd0.62Li0.15)TiO3 Ceramics Preparation and Thermoelectric Property Characterization BA Yao-shuai， BA De-chun 2019, 40 (10):  1403-1407.  DOI: 10.12068/j.issn.1005-3026.2019.10.007 Abstract ( 633 )   HTML   PDF (634KB) ( 581 )   The ABO3 perovskite(Nd0.62Li0.15)TiO3crystal ceramic was prepared by the solid phase reaction and pressureless sintering method， and its thermoelectric properties were characterized.The results from high-resolution transmission electron microscopy(HR-TEM)show that the prepared material has a nano-superlattice structure，which causes a strong scattering of phonons at the interfaces of nano-domains， resulted in a glass-state heat conduction characteristics of the material with a thermal conductivity less than 2W/(m·K).A-site vacancy compensation can increase the electrical conductivity dramatically，while it has little effect on the thermal conductivity. The distortion of TiO6 octahedra restricts Seebeck coefficient. In the range of the tested temperature， the maximum thermoelectric dimensionless figure of merit ZT is 0.019， corresponding to the temperature of 500K. References | Related Articles | Metrics

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Optimization of Rolling Force Self-learning Model in Unsteady Process of Hot Rolling PENG Wen， JI Ya-feng， CHEN Xiao-rui， ZHANG Dian-hua 2019, 40 (10):  1408-1412.  DOI: 10.12068/j.issn.1005-3026.2019.10.008 Abstract ( 643 )   HTML   PDF (523KB) ( 810 )   In order to improve the predicted precision of rolling force in unsteady process， an optimization method for rolling force self-learning model was proposed. The self-learning coefficient in the model was decomposed into the layer learning coefficient and rolling state learning coefficient， which characterized the genetic characteristics of rolling force prediction deviation between racks， and the effect of actual roll state on the model prediction. In the process of coefficient updating， the learning coefficients were updated according to the layer distance so that the prediction error of rolling force could be reduced， especially when the rolling specifications were switched. The proposed self-learning method has been successfully applied into a hot rolling process. Compared with the original model， the predicted deviation of the optimized self-learning method is reduced from 2.8% to 1.4%， and the mean square error is reduced from 3.3% to 1.7%， which effectively improve the accuracy and robustness of rolling force in unsteady process. References | Related Articles | Metrics

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Slab Heating Uniformity Based on Multi-field Coupling Heat Transfer in Reheating Furnace QI Feng-sheng， WANG Zi-song， LI Bao-kuan 2019, 40 (10):  1413-1418.  DOI: 10.12068/j.issn.1005-3026.2019.10.009 Abstract ( 688 )   HTML   PDF (1046KB) ( 654 )   A three-dimensional model， which fully coupled the combustion， flue gas flow， flue gas and billet heat transfer in an eight-staged walking beam reheating furnace in a steel plant was established. The billet motion was simulated by the dynamic mesh method. The heat transfer between flue gas and billet in furnace， temperature uniformity and temperature distribution of billet under different cushion structures(i.e.， a column of cushion block， thousand island cushion block and dislocation beam)were analyzed. The results show that the proposed numerical model for reheating furnace can accurately simulate the combustion， turbulence and heat transfer processes. The structure of cushion block has a decisive influence on the temperature distribution of the billet. Thousand island cushion block and dislocation beam can reduce the temperature difference of skid marks by 40% and 50%， respectively. The numerical model can successfully solve the problems of billet movement and the coupled heat transfer between flue gas and billet for the complex structures like walking beam， billet， pad block and water pipe column in walking beam reheating furnace. References | Related Articles | Metrics

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Extracting Soluble Calcium from Roasting Quicklime with Ammonium Chloride NING Zhi-qiang， SANG Chun-yuan， XIE Hong-wei， SONG Qiu-shi 2019, 40 (10):  1419-1423.  DOI: 10.12068/j.issn.1005-3026.2019.10.010 Abstract ( 714 )   HTML   PDF (530KB) ( 710 )   The calcium oxide was extracted by aqueous leaching roasted clinker of ammonium chloride and quicklime， and the effects of the roasting temperature， roasting time and molar ratio of ammonium chloride to quicklime on the extraction ratio of calcium oxide were studied to achieve a high value-added utilization for quicklime. The optimum roasting condition for extracting calcium oxide was obtained through the orthogonal tests. The results indicate that when the roasting temperature is 250℃， the roasting time is 90min， and the mole ratio of ammonium chloride to quicklime is 2.2∶1， the optimum roasting process can be achieved and the extraction ratio of calcium oxide is up to 97.26%. After differential thermal analysis， the process of roasting quicklime with ammonium chloride can be generally divided into three steps. References | Related Articles | Metrics

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Novel Process and Mechanism for Chemical Desilication from Kaolinite-Rich Diasporic Bauxite WU Yan， PAN Xiao-lin， HAN Yue-jiao， YU Hai-yan 2019, 40 (10):  1424-1429.  DOI: 10.12068/j.issn.1005-3026.2019.10.011 Abstract ( 838 )   HTML   PDF (856KB) ( 784 )   For the kaolinite-rich diasporic bauxite， a process route using chemical desilication was firstly proposed. The relationship between the equilibrium solubility of silica and the mass concentration of alumina， and the effect of lye concentration， temperature and time on the chemical desiliconization ratio of ore were studied. The results showed that the desilication ratio can reach 70% and the w○Al▲2O▲3/w○SiO▲2 of bauxite increases from 4.97 to 8.5 in the alkali solution with Na2O concentration of 230g·L-1 at 90℃ for 90min. The formation of DSP reduces the pre-desilication ratio and causes the loss of alkali. However， the conversion of kaolinite to DSP does not reduce the effective w○Al▲2O▲3/w○SiO▲2 of desilicated concentrate. References | Related Articles | Metrics

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Extraction of Impurities from Leaching Solution of Cathode Active Material of Spent Lithium Ion Batteries by Sulfuric Acid YI Ai-fei ， ZHANG Jian ， ZHU Zhao-wu ， QI Tao 2019, 40 (10):  1430-1436.  DOI: 10.12068/j.issn.1005-3026.2019.10.012 Abstract ( 906 )   HTML   PDF (787KB) ( 919 )   The effect of the formulation by the acid phosphine extractants of P204 with Lix54 and of P507 with Lix84 on the Al extraction from sulfuric acid leaching solution of cathode active materials of spent lithium ion batteries was studied. The results indicate that the P507+Lix84 formulation has the best extraction and separation effect on Al/Mn. When the optimal formulation of 5%P507+5%Lix84/kerosene is used and V○a/V○ois 1∶1 with pH of 4.0， the single-staged extraction rate of Al， Cu， Co， Ni， Mn and Li is 89.1%， 80.8%， 3.4%， 2.6%， 3.2% and 0.3%， respectively. When V○a/V○o is 1∶4， the Al concentration is 0.88g·L-1in the mother liquid and the Al extraction rate is higher than 97.7% after the two-staged(theoretical-level)extraction. With 2.0mol/L sulfuric acid solution in the oil phase and V○a/V○o of 10∶1， the Al concentration is 0.79g·L-1and the Al stripping rate is higher than 99.0% after the two-staged(theoretical-level)stripping process. References | Related Articles | Metrics

Mechanical Engineering

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Performance Comparison of GNES and LDVA in Vibration Suppression of Rotor Systems YAO Hong-liang， CAO Yan-bo， LI Qiu-feng， WEN Bang-chun 2019, 40 (10):  1437-1441.  DOI: 10.12068/j.issn.1005-3026.2019.10.013 Abstract ( 794 )   HTML   PDF (748KB) ( 593 )   In order to suppress the lateral vibration of anisotropic rotor systems， a grounded nonlinear energy sink(GNES)and a linear dynamic vibration absorber(LDVA)were designed. Firstly， the structure， working principles and some inherent characteristics of GNES were introduced. Then， the dynamic models and equations of the coupled systems composed of GNES， LDVA and rotor systems were established respectively. Finally， the vibration suppression effects of two kinds of vibration absorption devices were analyzed by the numerical method. The results showed that the vibration suppression performance of GNES is better than that of LDVA under the given parameters. References | Related Articles | Metrics

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Time-Varying Reliability Analysis of Turning Chatter EN Xi-nong， ZHANG Yi-min， HUANG Xian-zhen 2019, 40 (10):  1442-1447.  DOI: 10.12068/j.issn.1005-3026.2019.10.014 Abstract ( 566 )   HTML   PDF (543KB) ( 619 )   Considering the influence of tool wear on the cutting force coefficient in turning， the Gamma process was used to describe the change of cutting force coefficient with time， and a time-varying reliability model of turning chatter was established. A time-varying reliability analysis method(AK-SSFP)combining the Kriging model of active learning with the subset simulation based on the first passage was proposed. A model of turning vibration stability was established for a lathe. The Monte Carlo method(MCS)， the Monte Carlo method based on active learning Kriging(AK-MCS)and the AK-SSFP method were used to calculate the time-varying reliability of turning chatter. The results of the AK-SSFP method are in good agreement with the results of the MCS method， and the AK-SSFP method reduces the number of calls to the real limit function and shortens the computation time. AK-SSFP improves the calculation efficiency while ensuring the accuracy， and solves the calculation problem of time-varying reliability in turning chatter. References | Related Articles | Metrics

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Vibration Performance of Two-Stage Vehicle Suspension with Inerters LI Xiao-peng ， LI Fan-jie， CAO Zhou， YANG Ling-xue 2019, 40 (10):  1448-1453.  DOI: 10.12068/j.issn.1005-3026.2019.10.015 Abstract ( 950 )   HTML   PDF (560KB) ( 700 )   Based on the electromechanical similarity theory and the characteristics of the inerter， which is similar to the capacitor in the characteristics that high frequency can pass but low frequency cannot， a single wheel vehicle model of two-stage ISD suspension with "inerter-spring-damper"(ISD)in each level was established. The influence of the inertia coefficient of vehicle suspension on the transmission characteristics of the two-stage ISD suspension system was simulated and analyzed， and the dynamic response of the vehicle suspension system under random and pulse input was discussed in the frequency domain and the time domain respectively. The results showed that under the requirement of the acceleration gain of the vehicle body， the proper improvement of the inertia coefficient can improve the vibration damping performance of the two-stage ISD suspension system. The two-stage ISD suspension has a better low-frequency vibration damping performance than the classic ISD suspension.Compared with the traditional passive suspension， the two-stage ISD suspension has a better comprehensive vibration damping performance. References | Related Articles | Metrics

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Effect of Deflection Angles on Structural Characteristics of Circumferential Sealing and Leakage YAN Yu-tao， WANG Shuang， HU Guang-yang， ZHANG Li-jing 2019, 40 (10):  1454-1461.  DOI: 10.12068/j.issn.1005-3026.2019.10.016 Abstract ( 604 )   HTML   PDF (1171KB) ( 623 )   Based on the circumferential sealing analysis of deflection angles， the force model and the finite element analysis model were established. Through structural analysis and thermo-structural coupling analysis， the distribution of stress and deformation of the main and auxiliary sealing surfaces were obtained under different deflection angles， as well as the variation law of leakage gap and leakage amount. The stress and deformation of the main and auxiliary sealing surfaces are evenly distributed. The maximum stress and maximum deformation are located at the tongue. The maximum deformation of the main sealing surface is larger than that of the auxiliary sealing surface. The maximum stress and maximum deformation increase with the increasing of deflection angles. The thermal-structural coupling analysis stress and deformation are basically consistent with the structural analysis distribution， but they are larger than that in the structural analysis. The gap of the main sealing surface increases from the bearing chamber to the air chamber， and the gap of the auxiliary sealing surface increases from the center to both ends， and the gap at the joint is the largest. The amount of leakage increases with the increasing of deflection angles. References | Related Articles | Metrics

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Design and Analysis of Fiber-Reinforced Three-Cavity Structure of Soft Robot Hands FENG Nai-shi， WANG Hong， HU Fo， LI Kang 2019, 40 (10):  1461-1466.  DOI: 10.12068/j.issn.1005-3026.2019.10.017 Abstract ( 600 )   HTML   PDF (1153KB) ( 822 )   Based on the three-knuckle structure of a human hand， a fiber-reinforced three-cavity human-like soft body manipulator and a new type of pipe-laying method were proposed. The mathematical model of large deformation of the soft manipulator with a single finger was established by using Neo Hookean model. The deformation characteristics of the single-finger of the soft manipulator were analyzed， and the bending model and the torsion model were established. A 1∶1 mixture of Ecoflex 00-50 and Dragon skin 30 was used to make soft fingers， and the error correction of the theoretical model was carried out with the test data. The results showed that the theoretical model of the proposed new soft finger structure is consistent with the actual measurement data. Compared with the other structures， the new pipe-laying method increases the overall stability， and the conclusions can provide theoretical support for the development of human-like soft body manipulators. References | Related Articles | Metrics

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Experimental Study on Laser Heat-Assisted Grinding Quartz Glass YU Tian-biao， LIU Chuan-meng， YU Kui-dong， WANG Wan-shan 2019, 40 (10):  1467-1473.  DOI: 10.12068/j.issn.1005-3026.2019.10.018 Abstract ( 644 )   HTML   PDF (2190KB) ( 791 )   The effects of process parameters on the surface roughness， surface morphology and wear of the grinding wheel were studied by the orthogonal test after quartz glass was treated by laser heat assisted grinding. The results showed that laser heat-assisted grinding can improve the critical grinding depth， the surface grinding quality and work efficiency of quartz glass. The laser power has the greatest influence on the roughness of laser-assisted grinding， but there is no linear relationship. The optimal laser power is 175W， and the corresponding roughness is 0.262. With the aid of laser， the brittleness of glass decreases and the plasticity increases during the experiment， which realizes the plastic domain grinding of quartz glass， reduces the wear of the grinding wheel and decreases the peeling pit of the grinding surface. References | Related Articles | Metrics

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Regularization Parameter Determination Method of ICAA Based on Newmark-β FAN Yu-chuan， CHEN Ye， ZHAO Chun-yu， LU Ze-chen 2019, 40 (10):  1474-1479.  DOI: 10.12068/j.issn.1005-3026.2019.10.019 Abstract ( 519 )   HTML   PDF (1038KB) ( 683 )   When the traditional L-curve method is applied， it is often not easy to obtain accurate regularization parameters. Therefore， a new regularization parameter determination method of ICAA(inverse computation-contrast-adjustment-approach)based on Newmark-β was proposed. Compared with the traditional L-curve method， the algorithm is more intuitive and simple to use， and the calculation time is shorter and more efficient. The validity of the algorithm was verified by a simulation example of a four-DOF system and an experiment of a cantilever beam， and the load identification results of this algorithm were compared with the load recognition results of the L-curve method. The results showed that compared with the L-curve method， the proposed algorithm not only has greater advantages in computational efficiency， but also has higher accuracy in load identification calculation using the regularization parameters obtained by the algorithm. References | Related Articles | Metrics

Resources & Civil Engineering

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Influence of Strong Geomagnetic Storms on Global GNSS Observation Signals HE Li-ming， ZHANG Shi-xuan， WU Li-xin 2019, 40 (10):  1480-1486.  DOI: 10.12068/j.issn.1005-3026.2019.10.020 Abstract ( 675 )   HTML   PDF (1210KB) ( 867 )   A method for calculating the rate of loss-of-lock(LOL)at carrier phase and pseudo-range measurements of GNSS L1 and L2 was introduced， and the impacts of different satellite elevation angles on the LOL rate were also investigated. Using global GNSS observations， the qualities of GNSS signals during two strong geomagnetic storms at the 23rd solar cycle were analyzed. The results showed that the LOL rates of L1， L2， P1 and P2 signals significantly increased during strong geomagnetic storms comparing with the quiet days. The LOL mainly occurred in the main phase and the early recovery phase of the storm. The LOL rate of L2was significantly higher than L1， and the LOL duration was longer. This means the L2 was more sensitive to geomagnetic storm than L1. The high correlation between the LOL rate and SYM-H index indicated that the abnormal increase of global LOL rate was driven by the strong geomagnetic storm. The results could provide methodological support for the assessment of signal quality of the Beidou navigation satellite system. References | Related Articles | Metrics

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Advanced Denitrogenation of Urban Sewage with Pulse Electrosorption Technology JIN Zhao-yan， HU Xiao-min， SUN Tong， ZHAO Yan 2019, 40 (10):  1487-1491.  DOI: 10.12068/j.issn.1005-3026.2019.10.021 Abstract ( 538 )   HTML   PDF (548KB) ( 636 )   A pulse electrosorption reaction device was constructed， in which the pulse-switching power supply was used to replace the DC stabilized power supply adopted in the traditional electro-adsorption， and the activated carbon powder was used as the adsorbent material to prepare the electrode plate. The removal rates of NO3-N and NH3-N in the simulated wastewater using pulse electrosorption method and direct current adsorption method were compared and results show that the removal rate of the pulse electrosorption method is higher within 60min.Taking the removal rate of NO3-N as the index， the effects of duty cycle and frequency on nitrogen removal rate were also studied. The results show that the removal rate of NO3-N is the highest when the duty cycle is 50% and the frequency is 104Hz. References | Related Articles | Metrics

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Kinetics of Bioleaching for Copper Sulfide Ore with Different Grade JIANG Liang-you， WEI De-zhou， LIU Kai-kai， ZHANG Hao 2019, 40 (10):  1491-1495.  DOI: 10.12068/j.issn.1005-3026.2019.10.022 Abstract ( 616 )   HTML   PDF (727KB) ( 775 )   The copper-bearing minerals in the copper sulfide ore in the Jiama area of Tibet are mainly composed of secondary copper sulfide minerals with low content. The ore was bioleached using the column leaching method of Thiobacillus ferrooxidans and the leaching kinetics was studied. For different ore grades， the effects of particle size on copper leaching rate and leaching ratio were investigated. The leaching ratio and the control equation in the shrinkage nucleus model were fitted to determine the speed control link in the leaching process. The test results show that the leaching rate and leaching ratio of copper increase with the decrease of the grain size. The SEM of the surface morphology of the ore indicates that the product layer containing jarosite is formed on the surface of the ore during the leaching process， which hinders the progress of the leaching reaction. The leaching kinetics indicates that the leaching process of the ore is conformed to the shrinkage nucleus model， which is mainly controlled by the diffusion within the solid product layer. References | Related Articles | Metrics

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Viscoelastic-Plastic Damage Constitutive Model of Asphalt Mixture Under Cyclic Loading ZHANG Jun， LI Zhi-wei 2019, 40 (10):  1496-1503.  DOI: 10.12068/j.issn.1005-3026.2019.10.023 Abstract ( 727 )   HTML   PDF (1113KB) ( 966 )   In order to better describe the viscoelastic-plastic stress-strain relationship of asphalt mixture during damage process， and to clarify the effect of dynamic cyclic loading on the damage constitutive relation of the mixture，a viscoplastic element was connected in series to the Burgers viscoelastic model based on the classical viscoelastic plastic rheological theory. According to the strain equivalent principle of damage mechanics， a viscoelastic-plastic damage constitutive model of the asphalt mixture was established， which can reflect the dynamic cyclic loading characteristics and consider the influence of loading frequency. Then the indirect tensile fatigue tests were carried out to study the effects of loading frequency， ambient temperature， stress level， asphalt dosage and asphalt type on the stress-strain relationship of the mixture， and to calibrate the model parameters in order to verify the validity of the model. The results show that the model can not only better describe the damage constitutive relationship of asphalt mixture under dynamic cyclic loading， but also can reflect the influence of loading frequency， ambient temperature and load level on the stress-strain relationship of the mixture. Because the meaning of the parameters in the model is clear and regular， it deserves further research and promotion. References | Related Articles | Metrics

Management Science

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Service Quality Control of Supply Chains Under Different O2O Modes LI Yan-ting， ZHANG Cui-hua， LI Chun-yu， LYU Ru-xia 2019, 40 (10):  1504-1509.  DOI: 10.12068/j.issn.1005-3026.2019.10.024 Abstract ( 657 )   HTML   PDF (481KB) ( 672 )   In a supply chain consisting of an online platform and an offline service provider， the service quality control was studied by considering the two O2O modes of online platform service outsourcing mode and the offline service provider franchising mode. A basic model of service quality control under two modes was constructed， and the influences of service price elasticity， service quality cost coefficient， marketing effort cost coefficient on service price， service quality and marketing effort were analyzed.An equilibrium solution under centralized and decentralized decision was analyzed by numerical simulation. The results showed that service quality and marketing effort level are negatively correlated with service price elasticity. The decentralized decision-making in the offline service provider franchising mode leads to the effect of "double marginalization".When the profit distribution proportion obtained by the platform is small and the decentralized decision-making is made， the online platform chooses the service outsourcing mode or the service provider franchising mode. References | Related Articles | Metrics

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Dynamic Radiation of Creative Industries in Liaoning Province Based on Revised Industrial Radiation Intensity Model ZHAO Qi， LIU Fu-ying 2019, 40 (10):  1510-1516.  DOI: 10.12068/j.issn.1005-3026.2019.10.025 Abstract ( 591 )   HTML   PDF (1384KB) ( 543 )   Based on the breaking point theory， urban accessibility was measured by city relevance， relative degree centrality and intermediate center degree index， and the accessibility parameters were introduced to improve the urban radiation intensity model. Taking 14 prefecture-level cities in Liaoning province as the research object， the radiation effects of creative industries in each city from 2011 to 2017 were measured. Through the comparison of the spatial intensity distribution results of creative industries， the spatial distribution and pattern evolution of creative industries in Liaoning province are analyzed. The research results showed that traffic convenience has a positive effect on the development of creative industries. Liaoning’s creative industries are not closely linked and they are represented by two cores—Shenyang city and Dalian city， and two development routes—the Jingha route and the Bohai Sea route. According to the similarity of urban development intensity， economic ties of the same level cities should be strengthened. References | Related Articles | Metrics

Biologic Engineering

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Biomechanical Simulation of Artificial Lumbar Intervertebral Disc Replacement and Intervertebral Fusion LIU Chuang， LIU Qi， YAN Yun-hui 2019, 40 (10):  1517-1520.  DOI: 10.12068/j.issn.1005-3026.2019.10.026 Abstract ( 964 )   HTML   PDF (538KB) ( 629 )   The finite element method was used to evaluate the biomechanical effects of artificial lumbar intervertebral disc replacement and intervertebral fusion. Based on the CT image data， a finite element model of lumbar segments L2~L5 was established， and two kinds of surgical models of artificial lumbar disc replacement and intervertebral fusion were established. The simulated physiological load was applied to the finite element model， and the intervertebral activity and facet joint stress of each segment of the two surgical models were calculated. The simulation results showed that artificial lumbar disc replacement has a significant motion preservation in the surgical segment compared with intervertebral fusion，but the range of motion(ROM)were 40.9% and 43.1% higher than that of the normal lumbar in extension and lateral bending， which may cause mild instability of the surgical segment. Artificial disc replacement improves the stress state of the small joints of the upper and lower adjacent segments， but the replacement segment will induce higher contact pressure of the small joints under torsional conditions. References | Related Articles | Metrics