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15 October 2018, Volume 39 Issue 10 Previous Issue    Next Issue
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Information & Control

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Double-Mutation Partheno-Genetic Algorithm for Airport Ground Service Optimization TANG Fei， LIU Shu-an 2018, 39 (10):  1369-1374.  DOI: 10.12068/j.issn.1005-3026.2018.10.001 Abstract ( 574 )   HTML   PDF (611KB) ( 781 )   In order to reduce the flight delays caused by airport ground service task scheduling， a multi-objective nonlinear integer optimization model was established to minimize total flight delays and flight delay variance. Ground service task scheduling optimization is an NP-hard problem， so， a double-mutation partheno-genetic algorithm was proposed to solve this problem. The algorithm avoids the phenomenon that the genetic algorithm generates illegal individuals when solving similar problems， and the double-mutation strategy has global search capability. The simulation result showed that the double-mutation partheno-genetic algorithm can solve the ground service scheduling optimization problem including assignment of service teams to airlines and airline-service sequence optimization inside a service team， reduce the total flight delays caused by ground service tasks and avoid long single-flight delay. References | Related Articles | Metrics

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Community Discovery Algorithm for Multi-relationship Networks HUANG Xin-yu， CHEN Dong-ming， REN Tao 2018, 39 (10):  1375-1379.  DOI: 10.12068/j.issn.1005-3026.2018.10.002 Abstract ( 809 )   HTML   PDF (680KB) ( 822 )   The characteristics of the real social network were analyzed， and a network model with multi-relationships network between nodes was established. Based on this， the concept of influence of interaction between nodes was defined， and a community discovery algorithm for multi-relationship network (CDMN) was proposed. The rationality of the presented definitions was verified theoretically， and a series of experiments compared with other algorithms were conducted. Experimental results showed that the proposed community discovery algorithm for multi-relationship networks has higher accuracy and lower time complexity than other classical algorithms， and has important research significance and practical value. References | Related Articles | Metrics

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Salient Region Extraction Algorithm for Multi-target MENG Lu， CHEN Mei-ya 2018, 39 (10):  1380-1384.  DOI: 10.12068/j.issn.1005-3026.2018.10.003 Abstract ( 891 )   HTML   PDF (675KB) ( 829 )   Combining object estimation and super-pixel segmentation， a salient region extraction algorithm for multi-target was proposed. First， object estimation was used to make a preliminary extraction of multi-target in image， and the preliminary results of several salient regions were obtained. Then， these several salient regions were concatenated with the results of super-pixel segmentation to complete the saliency extraction. Finally， the concatenated regions were binarized as the final results of salient region for multi-target. The results showed that the proposed algorithm can achieve multi-target salient region extraction. The comparison with three classical algorithms indicated that the proposed algorithm is better when it is faced with salient region extraction for multi-target. References | Related Articles | Metrics

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Space Scales of Earthquake Data Relation Networks HE Xuan， WANG Lu-yang， ZHAO Hai， LIU Xiao 2018, 39 (10):  1385-1389.  DOI: 10.12068/j.issn.1005-3026.2018.10.004 Abstract ( 716 )   HTML   PDF (636KB) ( 693 )   By analyzing the topological structural characteristics of the earthquake data relation network in the California region of the United States， the changing rules of the basic metric parameters of the network topological structure under different space scales were studied. The results showed that with the increase of the space scales， the network scale rapidly becomes smaller and eventually reaches stability. The average clustering coefficient and the average shortest path length of the network decrease with fluctuations as space scales increase. The results of degree distribution frequency showed that when the space scales of the network are within a valid range， the network presents a better power-law distribution， which is affected by the number of events. References | Related Articles | Metrics

Materials & Metallurgy

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Effect of Through-Water Cooling on Microstructure and Mechanical Properties of GCr15 Bearing Steel HAN Huai-bin ， ZHAO Xian-ming， WANG Wei， WAN Chang- jie 2018, 39 (10):  1390-1395.  DOI: 10.12068/j.issn.1005-3026.2018.10.005 Abstract ( 869 )   HTML   PDF (3856KB) ( 845 )   The 20mm hot-rolled GCr15 bearing steels were obtained through four kinds through-water cooling processes. The effects of through-water cooling on microstructure and mechanical properties of the hot-rolled bearing steels and heat-treated bearing steels after spheroidizing annealing and quenching-tempering processes， respectively were investigated. The results showed that when the through-water cooling was carried out both before and after finish rolling and the finish-rolling and re-reddening temperature was 800~860℃ and 620℃， respectively， the temperature of phase transformation for the proeutectoid carbide and the pearlite went down， and the thickness and continuity of the proeutectoid carbide， the pearlite interlamellar spacing and the pearlitic colony size in the hot-rolled bearing steels were decreased. Accordingly， the thickness of carbide in the annealed and tempered microstructure was decreased while the homogeneity was enhanced. Moreover， the thick undissolved carbide networks were prevented. Eventually， the tensile strength and percentage of area reduction of the hot-rolled and heat-treated bearing steels were increased. References | Related Articles | Metrics

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Influence of Surface Treatment on Interface Bonding Properties of Titanium/Steel Composite Plate YANG De-han， LUO Zong-an， XIE Guang-ming， YU Huan 2018, 39 (10):  1396-1402.  DOI: 10.12068/j.issn.1005-3026.2018.10.006 Abstract ( 702 )   HTML   PDF (2557KB) ( 1174 )   Under the same heating temperature， rolling pass and pressure reduction by using vacuum roll cladding(VRC)，the interfacial microstructure and mechanical properties of three groups titanium/steel composite plates were studied after one of three different surface treatment methods which were wire brush grinding， pickling and polishing machine with water. The influence of surface treatment on the interfacial bonding properties was analyzed. The results showed that a uniform and continuous TiC layer is formed at the bonded interface when the surface treatment of the polishing machine with water is carried out. The fracture surfaces are full of dimples， the interfacial shear strength is stable with the average shear strength of 242.6MPa. However， the discontinuous TiC layers are formed in the interfaces of the titanium/steel plates subjected to the other two surface treatments and the shear strength of these two plates cannot meet the national standard. References | Related Articles | Metrics

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Numerical Simulation for Counterflow Convection-Film Cooling ofGas Turbine Combustor Liner with Ribbed Wall LI Bao-kuan， ZHANG Wen-bo， WANG Xi-chun 2018, 39 (10):  1402-1407.  DOI: 10.12068/j.issn.1005-3026.2018.10.007 Abstract ( 632 )   HTML   PDF (1585KB) ( 861 )   To study the cooling structure of gas turbine with counterflow convection-film for combustor liner， a fluid-solid coupling mathematical model of the cooling heat transfer of the combustor liner was established. Considering the propagation of Reynolds stress， the robustness of the k-ω model was used to capture the flow of viscous underlying layer in the near wall. The k-ε model was used in the mainstream areas to avoid the k-ω model being too sensitive to inlet turbulence parameters. The SST k-ω model was a turbulence model which was more suitable for this study by using a mixture function combined with the k-ω and the k-ε models. The results provided not only the distribution of flow and temperature fields in the computational domain fluid， but also the temperature distribution of the ribbed walls of the combustor liner. Moreover， these simulation results well agreed with the experimental ones. References | Related Articles | Metrics

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Construction and Analysis of Heating Furnace Oxy-Fuel Combustion System Based on Chemical Looping Oxygen Production WANG Kun， WANG Hong-jie， WEI Jia， ZHANG Ke-mu 2018, 39 (10):  1408-1412.  DOI: 10.12068/j.issn.1005-3026.2018.10.008 Abstract ( 807 )   HTML   PDF (594KB) ( 916 )   Based on the principle of chemical looping oxygen production， the oxy-fuel combustion system of heating furnace was built to solve the oxygen source problem.The feasibility of constructing the system was analyzed by investigating the characteristics of Co3O4 oxygen uncoupling. The results showed that the volume fraction of the equilibrium oxygen from the Co3O4 reduction increases sharply with the reaction temperature. When the temperature is 900℃， the volume fraction of the equilibrium oxygen is 29.6%.The components of CO2 and H2O in flue gas do not affect the oxygen release process of Co3O4. The oxygen volume fraction in flue gas increases with increasing the mole ratio of Co3O4 and flue gas. When the mole ratio is 1:1， the oxygen volume fraction can be up to 24.5% at 950℃. In practice， for a furnace with 32t/h output，when the oxygen-enriched rate is 4%， the Co3O4 filling capacity is 3.4t. References | Related Articles | Metrics

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Influence of Oxygen-Enriched Operation on Thermal State of Blast Furnace and Corresponding Countermeasures YU Xiao-bing， SONG Wen-gang， NI Wen-jie， ZOU Zong-shu 2018, 39 (10):  1413-1417.  DOI: 10.12068/j.issn.1005-3026.2018.10.009 Abstract ( 910 )   HTML   PDF (932KB) ( 1145 )   In order to further explore the smelting law under the oxygen-enriched blast furnace operation， a previous blast furnace oxygen-enriched comprehensive model was revised to study the thermal state of the blast furnace under different operating conditions. The results showed that furnace cylinder injection of circulating gas can effectively offset the increase of fuel ratio caused by oxygen enrichment operation， and in the low-oxygen enrichment operation， the blast furnace can meet the upper and lower heat balance without spraying the circulating gas. Increasing the amount of coal injection needs to correspond to increasing the oxygen enrichment rate， and different coal injections have different oxygen-enrichment operating intervals. From the model， the limit value of humidification under oxygen-enriched operation can be obtained， where the blast humidity should not exceed 21.2g/m3， and the corresponding oxygen enrichment rate maximum is about 4.6%. References | Related Articles | Metrics

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Effect of Particle Size on Dielectric Properties and Microwave Heating Characteristics of Ludwigite LIU Ya-jing， JIANG Tao， WANG Jun-peng， LIU Chen-hui 2018, 39 (10):  1418-1422.  DOI: 10.12068/j.issn.1005-3026.2018.10.010 Abstract ( 575 )   HTML   PDF (647KB) ( 660 )   The cavity perturbation method was used to measure the dielectric properties of ludwigite of different particle sizes at the frequency of 2.45GHz with the temperature ranging from 20 to 800℃， and heating characteristics under a microwave field were also measured.The results showed that with the decrease of particle size， the filling layer porosity of the ore sample decreases， while the dielectric properties and the heating rate increase.When the temperature is higher than 200℃， the thermal decomposition can generate a large number of micro-voids which increases the porosity， and the dielectric properties tend to be decreased， resulting in a reduce of heating rate during microwave heating.The effect of particle size on the dielectric properties and temperature rising characteristics of ludwigite provides a theoretical basis for the application of microwave in the fields of metallurgy and saving energy consumption. References | Related Articles | Metrics

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Thermal Decomposition Mechanism of Terbium Chloride Aerosol at High Temperature XUE Shou-feng， WU Wen-yuan， BIAN Xue 2018, 39 (10):  1423-1427.  DOI: 10.12068/j.issn.1005-3026.2018.10.011 Abstract ( 748 )   HTML   PDF (980KB) ( 802 )   Using TbCl3 aerosol as the precursor， the thermal decomposition mechanism of TbCl3 at high temperature was investigated from micro-and nano-scale in the condition of air atmosphere， and the phase composition and morphology of the pyrolysis products were characterized by XRD and FESEM， respectively. Based on the experimental results and thermodynamic analysis， it was discussed about the chemical reaction mechanism of the TbO2 formation by thermal decomposition of TbCl3 and kinetic reasons for promoting the conversion of TbCl3 to terbium oxide. The results showed that the thermal decomposition of TbCl3 could produce the stoichiometric form of TbO2， the non-stoichiometric form of Tb7O12 was obtained when the thermal decomposition temperature was above 800℃， and TbOCl was not found in the pyrolysis products. From intermediate compounds observed in the pyrolysis products of the TbCl3 aerosol， it is helpful to understand its property and thermal decomposition process. References | Related Articles | Metrics

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Separation of Nickel from Manganese， Magnesium and Calcium Using Synergistic Solvent Extraction System of P204/4PC ZENG Li， SUN Zhen， GUAN Wen-juan， ZHANG Gui-qing 2018, 39 (10):  1428-1432.  DOI: 10.12068/j.issn.1005-3026.2018.10.012 Abstract ( 971 )   HTML   PDF (516KB) ( 1253 )   The separation of nickel from manganese， magnesium and calcium by solvent extraction with new synergistic system was studied. The effects of organic phase ratio， equilibrium pH value and equilibrium time on extraction separation were investigated， and nickel extraction and stripping isotherms were plotted. The results showed that the organic phase composed of 1.25mol/L 4PC(L)+0.25mol/L P204(HA)was used after 5 levels of countercurrent extraction， the extraction rate of nickel reached 98.7%， and the extraction rate of other impurity metals were nearly below 5%. The loaded organic phase was subjected to a three-stage countercurrent stripping， the stripping rate of nickel reached 98.2%， and the content of nickel in the organic phase was less than 0.1g/L. References | Related Articles | Metrics

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Adsorption Behavior of Oxalate on Al(OH)3 in Sodium Aluminate Solution YU Hai-yan， WANG Jiang-zhou， ZHANG Bai-yong， PAN Xiao-lin 2018, 39 (10):  1433-1438.  DOI: 10.12068/j.issn.1005-3026.2018.10.013 Abstract ( 742 )   HTML   PDF (554KB) ( 767 )   The adsorption equilibrium and kinetics of oxalate on Al(OH)3 in sodium aluminate solution were studied by simulating the seed precipitation of the Bayer process， and the effects of initial oxalate concentration and the particle size of Al(OH)3 on adsorption were also investigated. The results showed that Al(OH)3 has a good adsorption ability on sodium oxalate. With increasing initial sodium oxalate concentration and decreasing particle size of Al(OH)3， the equilibrium adsorption rate increases and the equilibrium adsorption time decreases. The adsorption capacity for different particle size of Al(OH)3 is different due to the different specific surface area. The adsorption isotherm pattern of sodium oxalate on Al(OH)3 fits the Freundlich model well and the adsorption process can be described by the pseudo-second-order equation. The adsorption of oxalate on Al(OH)3 is a multilayer adsorption， associated with physical and chemical adsorption processes. References | Related Articles | Metrics

Resources & Civil Engineering

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Geochemical Features and Tectonic Significances of Yuanjiacun Formation Metasedimentary Rocks in Shanxi Province MEN Ye-kai， GENG Rong-rong， YOU Xin-wei， HE Qiang-wen 2018, 39 (10):  1438-1441.  DOI: 10.12068/j.issn.1005-3026.2018.10.014 Abstract ( 651 )   HTML   PDF (927KB) ( 751 )   Early proterozoic Yuanjiacun Formation is the main ore bearing stratum in Lyuliang district. The elemental geochemical compositions of the samples were tested. Results showed that the major element is mainly SiO2， then is Al2O3， TFeO and K2O in sequence. SiO2 exhibits negative correlation with the other major oxides， and LILE and HFSE are significantly rich. The rare earth element distribution curves take on obvious right-divergent characteristics， with strong fractionations of light and heavy rare earth and rich light rare earth. The Ce anomalies are extremely weak， and the range of Eu anomalies is relatively large. The Yuanjiacun Formation is parametamorphite， and the original rock is dominated by sedimentary rock with weak weathering during the deposition process. The provenance attributem is dominated by high-mature upper crustal felsic sediments mixed by small amount of rocks containing ancient sedimentary components and andesitic arc igneous rock components in the sedimentary process. The tectonic environment is passive continental margin. References | Related Articles | Metrics

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Numerical Simulation on Characteristics of Internal Flow Field in Flocculation Agitator WANG Xue-tao， CUI Bao-yu， WEI De-zhou， GAO Shu-ling 2018, 39 (10):  1442-1446.  DOI: 10.12068/j.issn.1005-3026.2018.10.015 Abstract ( 624 )   HTML   PDF (1114KB) ( 968 )   Based on the gas-liquid interface morphology comparison， LDV test verification and CFX immersed solid model， a numerical study was conducted on the characteristics of internal flow field in a 1 L flocculation agitator by using the standard k-ε turbulence model. Results indicated that the velocity and its gradient are higher in the downward recirculating flow region， and the velocity gradient increases with the increase of stirring intensity. The rotational speed has larger influence on the tangential velocity gradient near the impeller， where the tangential velocity gradient is larger than that in other regions by two orders of magnitude. The turbulent dissipation rate， turbulent kinetic energy and eddy viscosity are higher in the downward circulation area. The rotational speed of impeller in the range of investigation has a larger impact on the turbulence kinetic energy， and a relatively small impact on the eddy viscosity. References | Related Articles | Metrics

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Seepage Channel Formation Process of Mine Grout Curtain LIU Hong-lei， ZHOU Jing-ren， YANG Tian-hong， ZHANG Peng-hai 2018, 39 (10):  1447-1452.  DOI: 10.12068/j.issn.1005-3026.2018.10.016 Abstract ( 600 )   HTML   PDF (1273KB) ( 733 )   According to the curtain leakage phenomenon and the drainage test results in Zhangmatun iron deposit grout curtain， the seepage channel formation process was studied through the microseismic activities induced by the collapse of the curtain and its surrounding rock masses. Results showed that the formation of seepage channel is mainly affected by the distance between mining activities and the grout curtain. The periodically mining activities， close or away from the grout curtain， lead to periodical stress changing in the curtain and the surrounding rock masses， thus resulting in the periodical activation of microseismic activities surrounding the curtain. Because the formation of water seepage channel and its development are accompanied by a large number of microseismic events， the location of the seepage channel， its formation process and related mechanism can be well determined and understood by microseismic monitoring technique， which is a promising method for the stability assessment of the grouting curtain. References | Related Articles | Metrics

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Verification and Analysis of Three-Phase Coupling Model for Soil Slope Under Rainfall Conditions WANG Shu-hong， YANG Tian-jiao， LIU Huan， TONG Ke-hui 2018, 39 (10):  1453-1457.  DOI: 10.12068/j.issn.1005-3026.2018.10.017 Abstract ( 749 )   HTML   PDF (742KB) ( 1166 )   Based on the basic theory of unsaturated soil mechanics， a solid-liquid-gas three-phase coupling control equation for two-dimensional unsaturated soil slopes was established by considering the compressibility of porous media. The numerical simulation results of the established coupling control equations based on the PDE platform of COMSOL multiphysics software was compared with the experimental results of the classical Liakopoulos sand column. The established three-phase coupling control equation was verified， and the influences of different factors on the seepage field and displacement field were discussed. The simulation results showed that the permeability can slightly retard the rainfall seepage process and delay the deformation of unsaturated soil slope. The air intake coefficient has a slight impact on the settling process of unsaturated soil slope. References | Related Articles | Metrics

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Ultrasonic Wave Testing on Damage Condition of Concrete Filled Steel Tube Under Axial Loading CHEN Meng， CHEN Xi-zhuo， CHEN Geng-ye， ZHAO Jun-zhi 2018, 39 (10):  1458-1462.  DOI: 10.12068/j.issn.1005-3026.2018.10.018 Abstract ( 583 )   HTML   PDF (1147KB) ( 717 )   Axial compression tests were conducted on high-strength concrete-filled thin-walled steel tubular short columns with three kinds of wall thickness combined with ultrasonic testing on the middle cross section of the column. The waveforms under different axial loads were analyzed through fast Fourier transform to obtain the frequency spectrum when ultrasonic waves passing through the concrete-filled steel tube. The damage process of concrete in the steel tube can be reflected by the waveform， the maximum amplitude and the frequency spectrum of the waveforms under different loads. The experiment results showed that the damage process of concrete under axial loading takes on a three-stage characteristic， which can be divided into the extension of initial cracks， the compaction due to the hooping effect and the failure of the concrete. The strain changing on the outer wall of the steel tube agrees with the damage process reflected by waveform and spectrum analysis. The ultrasonic testing method can be applied to accurately measure the damage condition of concrete in the steel tube under axial loading. References | Related Articles | Metrics

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Deformation Characteristics and Key Parameters of Deep Excavation Adjacent to Buildings with Shallow Foundations HAN Jian-yong， ZHAO Wen， GUAN Yong-ping， JIA Peng-jiao 2018, 39 (10):  1463-1468.  DOI: 10.12068/j.issn.1005-3026.2018.10.019 Abstract ( 618 )   HTML   PDF (1830KB) ( 873 )   Based on the in situ observation and numerical simulation， the deformation characteristics of the retaining structure of a deep excavation and the existing building were investigated. According to the in situ observations and available literatures， parametric studies were conducted using FEM to investigate the deformational behaviors of the excavation adjacent to existing building. The relationships between the deformation of the retaining structures and the settlement of the adjacent building under various construction conditions were fully revealed. Results showed that the tieback anchored pile wall has a good deformation control capacity and can be applied effectively in Jinzhou area. The corner effect of the rectangular excavation is significant with a plain strain ration (PSR)of about 0.4~0.6.The linear relationship between the average building settlement (δva) and the maximum horizontal deformation of the retaining structure (δhm) is slightly influenced by the existing foundation depth and the excavation depth. The discreteness of δva and δhm appears when the distance between the building and the retaining structure (L) changes， however the δva/δhm decreases gradually with the increase of L. References | Related Articles | Metrics

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Enhancement of Baghouse Filter with Corona Electret HE Wei-dong， GUO Ying-he， CHANG De-qiang， LIU Jing-xian 2018, 39 (10):  1469-1474.  DOI: 10.12068/j.issn.1005-3026.2018.10.020 Abstract ( 647 )   HTML   PDF (708KB) ( 751 )   5 typical needle felts were treated by multiple needle corona discharge to study the optimal electret filter， charge parameters and the performances of electret filter such as particle capture efficiency and charge stability. The results showed that the efficiency of all types of filters were improved in different extent: the increase of filtration efficiency of the polytetrafluoroethylene(PTFE)membrane filter is the largest with the smallest attenuation. The charge reservation percentage after a month of the PTFE filter treated under the condition of 15kV of charging voltage， 2cm of electrode distance and 20min of charge time is 62.22% with less than 0.9% of filter efficiency reduction for particles smaller than 1μm. After heat treatment of 200℃， the average charge reservation percentage of PTFE is 56.15%， and the efficiency reduction for particles smaller than 1μm is less than 1.23%. The charge technology has a prominent enhancement effect for PTFE membrane filter. References | Related Articles | Metrics

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Mechanical Properties of Sewing Thread in Dust Filter Bag Under Thermal Condition LIU Jing-xian， SHU Rui， CHEN Ming-gang， LI Yong-guang 2018, 39 (10):  1474-1479.  DOI: 10.12068/j.issn.1005-3026.2018.10.021 Abstract ( 648 )   HTML   PDF (1593KB) ( 739 )   The effect of temperature on the mechanical properties of PTFE， PPS， aramid， PAN and PET sewing threads for baghouse in the temperature range of 20 ~ 300℃ was studied using a powerful machine equipped with a heating box. The results showed that the experiment of hot stretching can better explain the effect of temperature on properties of the sewing thread under actual working conditions than that of cooling and re-stretching after baking. PTFE sewing thread is significantly affected by temperature. PPS sewing thread can still have good thermal stability at 240℃. Aramid sewing thread， although its strength is slightly lower， has good heat resistance ability with little strength changing. The strength of PAN sewing thread decreases sharply over 120℃. The mechanical properties of PET sewing thread are less affected by temperature， but cannot be used under high temperature. The mechanical behavior of each sewing thread is not the same under thermal conditions， but the overall strength is low. Because the high temperature soot trapping filter bag is affected by the external force caused by filtration and pulse jetting， the filter bag is much more likely to fail due to the break of the sewing thread. References | Related Articles | Metrics

Mechanical Engineering

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Damping Characteristics of Twin-Tube Hydraulic Shock Absorber with Elastic Supporting Slices LI Chao-feng， SHE Hou-xin， LI Chao， WEN Bang-chun 2018, 39 (10):  1480-1485.  DOI: 10.12068/j.issn.1005-3026.2018.10.022 Abstract ( 820 )   HTML   PDF (1229KB) ( 960 )   A mechanic model of circular elastic supporting slices was established under partial load， and the influential law of slices deformation was discussed. The exclusive testing machine was used to study its damping characteristics， which was then compared and verified with that of the theoretically deduced results. The influence of different key parameters on the damping characteristics of shock absorbers was studied. The results showed that with the increase of spring stiffness and slices thickness， the damper force of rebound stroke of shock absorber increases， and the greater the speed， the big increase in damping force. The area of pressure acting on the circular slices also has a significant influence on the damping force， so it is recommended that this parameter should be examined during the design phase of the shock absorber to extend the product performance interval. The results may provide reliable and accurate theoretical reference for the design of twin-tube hydraulic shock absorber with elastic supporting slices. References | Related Articles | Metrics

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Reducing Friction Mechanism of Superalloy Axial Ultrasonic Vibration Drilling CHEN Shuo， ZOU Ping， TIAN Ying-jian， MAO Liang 2018, 39 (10):  1485-1489.  DOI: 10.12068/j.issn.1005-3026.2018.10.023 Abstract ( 653 )   HTML   PDF (1438KB) ( 706 )   In view of difficulties in drilling high-temperature alloys and large friction during drilling， ultrasonic machining was used. Firstly， the reducing friction mechanism of ultrasonic vibration was analyzed， the relationship between the average friction force and vibration parameters was constructed， and then the correlation between the average friction force and amplitude was obtained. An axial ultrasonic vibration drilling system was established， which was used to drill the superalloy. The results showed that the effect of amplitude on the surface quality of hole wall is consistent with anti-friction characteristics of ultrasonic vibration. Compared with that of the ordinary drilling， the production of optimized amplitude ultrasonic vibration drilling yields more regular chip morphology， smooth hole wall surface roughness， and better surface quality. References | Related Articles | Metrics

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Oil Film Characteristics of Deep-Shallow Pocket Hybrid Bearing ZHANG Yao-man， YU De-guang， YANG Qing-bo 2018, 39 (10):  1490-1494.  DOI: 10.12068/j.issn.1005-3026.2018.10.024 Abstract ( 721 )   HTML   PDF (1340KB) ( 1115 )   The deep-shallow pocket hybrid bearing of spindle assembly of the high precision CNC lathe was taken as the object， the computational fluid dynamics software was used to analyze oil film characteristics of deep and shallow pocket hybrid bearing on the basis of theoretical modeling and analysis. The influence of speed， oil pressure， eccentricity， oil film thickness and angle of deep pocket on the bearing capacity， flow and temperature rise of the oil film were analyzed. The results showed that the flow of the oil inlet hole increases first and then decreases with the increase of the spindle speed， and gradually decreases with the increase of the eccentricity of the spindle. The oil film temperature gradually decreases with the increase of the external oil supply pressure and tends to be gentle. When the oil film thickness is about 0.03mm， the bearing capacity and temperature rise are most suitable. When the angle of the deep cavity is 10°， the dynamic pressure effect of the oil film is the most obvious， and the oil film bearing capacity is the strongest. References | Related Articles | Metrics

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Tooth Surface Wear of Spur Gears with Oil Lubrication ZHANG Jian-ge， LIU Shao-jun， FANG Te， JIN Yan 2018, 39 (10):  1495-1501.  DOI: 10.12068/j.issn.1005-3026.2018.10.025 Abstract ( 701 )   HTML   PDF (1712KB) ( 925 )   High-speed heavy-duty gears often work in a mixed lubrication state. In order to accurately predict the wear level of tooth surfaces， a wear analysis model of oil-lubricated gears was proposed to enable accurate description of the wear process of mixed lubrication tooth surfaces at the microscopic dimensions. The non-Gauss rough surface was generated according to the as-measured tooth profile characteristics， and the coupling results of thermal-stress were used as the working conditions and initial conditions of mixed lubrication analysis. Then pressure distribution， lubrication state and wear trend of the tooth surface were studied to reveal the wear mechanism. The results showed that surface wear of oil lubricated gears is affected by miscellaneous factors. In particular， the shape and distribution direction of asperity have a significant effect on wear degree. The prediction results show good agreement with the experimental measurements. It indicates that the wear prediction method of mixed lubrication tooth surface has practical engineering significance. References | Related Articles | Metrics

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Influence of ZrO2 Coating on Basement Damping Characteristics DU Guang-yu， TAN Zhen， LIN Zeng， BA De-chun 2018, 39 (10):  1501-1505.  DOI: 10.12068/j.issn.1005-3026.2018.10.026 Abstract ( 572 )   HTML   PDF (1480KB) ( 770 )   The ZrO2 coatings were deposited onto TC4 substrate by electron beam physical vapor deposition to explore the mechanism of its effect on the damping of the substrate. The surface morphology and structural properties of the coatings were characterized by SEM and XRD， while the damping properties of the coatings were measured using the dynamic mechanical analyzer(DMA). The results showed that， with the temperature increasing， the grain size becomes larger， the micro-defects decrease， the thin layer loss factor produces a hybrid orientation， the loss factor increases， and the damping performance improves. At high frequencies， due to the compensation effect， the grain boundaries defects of the mixed crystal orientation in the coating disappear， which hinders the further improvement of the damping characteristics of the coating. The damping performance is the best when the substrate temperature is 400℃ and the frequency is 55Hz. References | Related Articles | Metrics

Management Science

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Efficiency Evaluation and Comparison of Commercial Banks Based on Bootstrap-DEA WANG Jia， JIN Xiu， WANG Xu， WANG Shu-li 2018, 39 (10):  1506-1511.  DOI: 10.12068/j.issn.1005-3026.2018.10.027 Abstract ( 748 )   HTML   PDF (349KB) ( 1041 )   The Bootstrap method was introduced into the DEA model. Under the conditions of constant return to scale and variable return to scale， the initial DEA efficiency values of the China 67 commercial banks were rectified before and after financial crisis. The efficiency values of the state owned commercial banks， joint-equity commercial banks and city commercial banks were compared. The Bootstrap truncated regression method was used to test the factors affecting bank efficiency. The empirical results showed that the DEA efficiency values adjusted by Bootstrap are significantly lower than the initial DEA values. Compared with the state owned commercial banks， the efficiency levels of joint-stock commercial banks and city commercial banks are greatly affected by the financial crisis. The bank technical efficiency can be improved by properly expanding bank size， increasing profitability and innovation ability， while excessive revenue expenses and excessively dispersed ownership structure will reduce the technical efficiency of banks. References | Related Articles | Metrics

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Network Topology Struture of China Stock Market Under Extreme Volatility of Stock Indexes ZHANG Wei-ping， ZHUANG Xin-tian， LI Yan-shuang 2018, 39 (10):  1511-1515.  DOI: 10.12068/j.issn.1005-3026.2018.10.028 Abstract ( 778 )   HTML   PDF (856KB) ( 787 )   Stock market network was constructed by using the minimum spanning tree method to study the evolution of MST structure， the topological indicators and individual behavior characteristics of the key nodes at different periods before， during and after the extreme volatility of stock indexes. The results showed that the China′s stock market industry has a strong concentration and industry-wide homogeneity. The MST network shrinks during extreme volatility， and the network expands after volatility. In the middle and late periods of extreme volatility， the sudden emergence of the materials industry and information technology industry occupies an important position in the network. The extreme volatility caused by different infectious sources has different ways of transmission risk. Extreme volatility in stock indexes exacerbates the linkage between stocks， assets are reconfigured in the market and the network structure is undergone new adjustments. References | Related Articles | Metrics

Biologic Engineering

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Effect of Risedronate on Physicochemical and Biological Properties of Calcium Phosphate Silicate GONG Tian-xing， MI Hao-yang， CHEN Ya-dong， ZHANG Jing-shu 2018, 39 (10):  1516-1520.  DOI: 10.12068/j.issn.1005-3026.2018.10.029 Abstract ( 628 )   HTML   PDF (942KB) ( 740 )   Risedronate (0.5% and 1.0%) was mixed with bone cement powder containing calcium phosphate silicate for hydration reaction. The curing time and compressive strength of bone cement were measured and the microsturctural changes before and after drug loading were analyzed. The biological properties of bone cement were analyzed by detection of cytotoxicity and gene expression levels. The results showed that the best proliferation and differentiation of osteoblasts were obtained at 0.5% drug level.The drug can delay the curing of bone cement， but the porosity of bone cement decrease and the crystal structure become tighter.The calcium phosphate silicate cement containing risedronate acid has good biocompatibility and the mechanical strength similar to cancellous bone， which is prosperous in the application of a bone tissue repair material. References | Related Articles | Metrics